Automatic coating method and apparatus

TECHNICAL FIELD

This invention relates to an automatic coating method for carrying out coating operations in various colors automatically by selectively loading and unloading paint cartridges of different colors into and from a coating apparatus, and an automatic coating apparatus therefor.

BACKGROUND ART

Generally, for coating objects like vehicle bodies, for example, rotary atomizing head type coating apparatus which are equipped with a rotary atomizing head have been in wide use. Lately, coating apparatus of this sort are increasingly required to meet demands for reductions of the amounts of paint and solvent to be discarded at the time of color changes and for capability of coping with a large number of paint colors.

As a first example of the prior art of this category, Japanese Laid-Open Patent Publication No. H8-229446 describes a rotary atomizing head type coating apparatus which is so arranged as to reduce the amounts of discarding paint and solvent and which can cope with an increased number of paint colors. This rotary atomizing head type coating apparatus employs paint cartridges which are filled with different paint colors and adapted to be selectively and replaceably mounted on the coating apparatus in the course of a coating operation on vehicle bodies. However, no description is given in this prior art with regard to an apparatus for changing the paint cartridges.

As a second example of the prior art, there has been known an automatic coating apparatus (e.g. from Japanese Laid-Open Patent Publication No. S63-175662) which is arranged to perform a coating operation automatically according to programmed procedures. According to this prior art automatic coating apparatus, paint cartridges of various colors are located within a working area of a coating robot or other working mechanism, and, at the time of cartridge replacement, the working mechanism is operated to serve as a cartridge changer. Therefore, in this case each one of the paint cartridges needs to be located within a reach of the working mechanism. However, actually there is a limit to the number of paint cartridges which can be located within a working area of a working mechanism.

Further, as a third example of the prior art, there has been known an automatic coating apparatus as described in International Gazette WO97/34707. This third prior art coating apparatus is comprised of a working mechanism such as a coating robot which is provided in a coating area, a coating machine which is mounted on the working mechanism and provided with a rotary atomizing head adapted to be put in high speed rotation by an air motor for atomizing paint into finely divided particles, a number of paint cartridges which are filled with paint of different colors and adapted to be replaceably mounted on the coating machine, and a cartridge changer which is arranged to support the respective paint cartridges and mount and dismantle a paint cartridge on and from the coating apparatus for cartridge replacement.

In this case, the cartridge changer is provided with a round support table which is arranged to support a large number of paint cartridges in an annular array. The cartridge support table is turned by a drive motor or the like to bring a paint cartridge to be used for a coating operation, to a predetermined pick-up position.

In the case of the third prior art automatic coating apparatus which is arranged in the manner just described, paint is supplied from a cartridge to a coating machine of the coating apparatus to spray the paint toward a coating object. At this time, the working mechanism is put in operation to move the coating apparatus along contours of coating surfaces of a coating object.

When changing the paint color, the working mechanism is moved to bring the paint cartridge on the coating apparatus to a predetermined cartridge changing position of the cartridge changer. Then, a cartridge gripper which is provided on the side of the cartridge changer is operated to remove a consumed or empty paint cartridge from the coating apparatus and return same to the cartridge support table. Nextly, a fresh paint cartridge which is filled with a next color is picked up from the cartridge support table and mounted on the coating apparatus.

The cartridge changer according to the prior art just mentioned is arranged to locate a selected one of the paint cartridges on the cartridge support table in a predetermined pick-up position by turning the support table, and mounted on the coating apparatus in place of a cartridge of a previous color.

However, the cartridge support table, which carries a large number of paint cartridges in an annular array, is necessarily large in size and weight. It follows that, for driving the cartridge support table, the cartridge changer is required to have a drive motor with large driving power. Needless to say, a cartridge changer of a large size is disadvantageous in that it invites increases in cost.

DISCLOSURE OF THE INVENTION

In view of the above-mentioned problems with the prior art, it is an object of the present invention to provide an automatic coating method and apparatus for putting the method into practice, in which a large number of paint cartridges of different colors are arranged and located in such an efficient manner as to facilitate cartridge replacements and to realize reductions in size and cost of the coating apparatus in addition to improvements in working efficiency.

In order to achieve the above-stated objective, according to the present invention, there is provided an automatic coating method which is applied by the use of a working mechanism located in a coating area, a coating apparatus mounted on the working mechanism and adapted to be replaceably loaded with paint cartridges of various colors, and a cartridge changer including a paint replenishing means for replenishing paint into the paint cartridges and a cartridge gripper means having a couple of gripper members for gripping paint cartridges separately thereon and adapted to hand over paint cartridges to and from the coating apparatus to replace an empty paint cartridge on the coating apparatus by a replenished paint cartridge.

The automatic coating method according to the present invention comprises: coating step of coating object by the coating apparatus loaded with a replenished paint cartridge and moved by the working mechanism; a replenished paint cartridge picking up step of picking up said replenished paint cartridge of a color to be used in a next coating operation from a paint replenisher means by the use of one of the gripper members of the cartridge gripper means; an empty paint cartridge unloading step of unloading said empty paint cartridge from the coating apparatus by the use of the other one of the gripper members of the cartridge gripper means having the replenished paint cartridge still gripped in one gripper member; the replenished paint cartridge loading step of loading said replenished paint cartridge into the coating apparatus by one gripper member of the cartridge gripper means having the empty paint cartridge still gripped on the other gripper member; and returning the unloaded empty paint cartridge to the paint replenishing means.

With the arrangements just described, in the coating step, the working mechanism is put in motion to perform a coating operation by the coating apparatus which is loaded with a replenished paint cartridge. In the step of picking up a replenished paint cartridge, a replenished paint cartridge is gripped and picked up from the paint replenishing means by one of the gripper members of the cartridge gripper means. Nextly, in the empty cartridge unloading step, the empty paint cartridge is picked up from the coating apparatus by the other gripper member of the cartridge gripper means while gripping the replenished paint cartridge by one of the gripper members of the cartridge gripper means. In the replenished paint cartridge loading step, the replenished paint cartridge is loaded into the coating apparatus by one of the gripper members of the cartridge gripper means while gripping the empty cartridge by the other gripper member of the cartridge gripper means. Thus, in the empty cartridge returning step, a replenished paint cartridge and an empty paint cartridge are exchanged between the coating apparatus and the cartridge changer.

According to the present invention, there is also provided an automatic coating apparatus suitable for putting the above-described method into practice, which basically includes a working mechanism located in a coating area, a coating apparatus mounted on and moved by the working mechanism and adapted to be replaceably loaded with paint cartridges of various colors, and a cartridge changer arranged to hand over paint cartridges to and from the coating apparatus to replace an empty paint cartridge on the coating apparatus by a replenished paint cartridge.

The cartridge changer used in the automatic coating apparatus according to the present invention comprises: a paint replenishing means having a number of paint replenishers correspondingly for different paint colors, each adapted to support and replenish a paint cartridge of a corresponding color; a cartridge transfer means arranged to transfer paint cartridges in the directions of three perpendicularly intersecting axis; and a cartridge gripper means supported on the cartridge transfer means and adapted to grip and transfer paint cartridges between the coating apparatus and the paint replenishing means.

With the arrangements just described, upon finishing a coating operation, the coating apparatus with an empty paint cartridge is located at a cartridge replacing position, whereupon the cartridge means is actuated to move the cartridge gripper means toward that position. At this time, the cartridge gripper means is operated to transfer and exchange an empty paint cartridge and a replenished paint cartridge of a next color between the coating apparatus and the paint replenishing means. Besides, in preparation for use in a next coating operation, the empty paint cartridge which has been handed over to and set on the paint replenishing means is replenished with paint concurrently with a coating operation by the coating apparatus.

The coating apparatus to be used in the present invention is preferably constituted by a cartridge mount portion to be replaceably loaded with paint cartridges, and a coating machine with a rotary atomizing head for atomizing and spraying paint supplied from a paint cartridge loaded in the cartridge mount portion.

With the arrangements just described, as soon as paint is spurted out from a paint cartridge which is loaded in the cartridge mount portion, it is atomized into finely divided particles and sprayed toward a coating object by the rotary atomizing head of the coating machine.

Further, preferably, the paint cartridges to be used in the present invention are each constituted by a container to be filled with paint, and a feed tube extended axially from one end of the container, and the paint replenishing means is adapted to replenish paint into the container of the paint cartridge through a fore end of the feed tube.

With the paint cartridge construction just described, paint can be replenished into the container of a paint cartridge which has been handed over to and set on the paint replenishing means, thereby utilizing the fore end of the feed tube as a replenishing port.

In this instance, preferably, the paint cartridges are each constituted by a container to be filled with paint and a feed tube axially extended from a fore end of the container, and the paint replenishing means is constituted by a plural number of replenishing stools for replenishment of various paint colors, each having a feed tube passage hole formed axially therein to receive the feed tube of a corresponding paint cartridge, and a connector member located in the replenishing stool located in a deeper position than the feed tube passage hole to connect the fore end portion of the feed tube to a paint supply passage.

With the arrangements just described, when an empty paint cartridge is returned to a replenishing stool, the feed tube of the cartridge is inserted into the feed tube passage hole on the side of the stool until its fore end is connected to the connector member for communication with the paint supply passage. Therefore, paint which is supplied to the paint supply passage is replenished into the container via the connector member and the feed tube.

Further, preferably the cartridge transfer means to be used in the present invention is constituted by a first transfer mechanism arranged to move the cartridge gripper means in a longitudinal or transverse direction of the paint replenishing means, a second transfer mechanism arranged to move the cartridge gripper means in a transverse or longitudinal direction, and a third transfer mechanism arranged to move the cartridge gripper means in a vertical direction, and the cartridge gripper means is supported on the third transfer mechanism.

With the arrangements just described, the cartridge gripper means is moved in longitudinal, transverse and vertical directions by the first to third transfer mechanisms and located in the cartridge replacing position or in a cartridge pick-up position over a selected one of paint cartridges which are supported on the paint replenishing means. In addition, the cartridge gripper means is moved vertically up or down by the third transfer mechanism at the time of lifting up or lifting down a paint cartridge from or onto the coating apparatus or paint replenishing means.

Further, preferably the cartridge gripper means to be used in the present invention is provided with a couple of gripper members side by side to grip a couple of paint cartridges separately and independently of each other.

With the arrangements just described, a replenished paint cartridge is gripped in one of the gripper members of the cartridge gripper means at the time when an empty paint cartridge is unloaded from the coating apparatus by the other one of the gripper members at the time of replacement. Therefore, the replenished paint cartridge can be loaded into the coating apparatus immediately after removal of the empty paint cartridge.

Further, according to the present invention, the cartridge changer is provided with a shock absorber provided between the cartridge transfer means and the cartridge gripper means to permit movements of the cartridge gripper means relative to the cartridge transfer means when brought into abutting engagement with a paint cartridge.

With the arrangements just described, when the cartridge gripper means is moved toward and abutted against a paint cartridge by the cartridge transfer means, the shock absorber permits the cartridge gripper means to move for buffering the impacts of abutment.

Further, according to the present invention, the automatic coating apparatus further comprises a washer means which is located in the vicinity of a cartridge replacing position of the cartridge changer for washing the coating apparatus each time when replacing an empty paint by a replenished paint cartridge of a different color.

With the arrangements just described, when the coating apparatus is located in a cartridge replacing position for cartridge replacement, deposited previous color on the coating apparatus can be washed off by the washer.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1

is a front view of an automatic coating apparatus with a cartridge changer embodying the present invention;

FIG. 2

is an enlarged vertical sectional view of a rotary atomizing head type coating apparatus shown in

FIG. 1

;

FIG. 3

is an enlarged vertical sectional view of a rotary atomizing head shown in

FIG. 1

;

FIG. 4

is a vertical sectional view of a paint cartridge on an enlarged scale;

FIG. 5

is an enlarged front view of a cartridge changer shown in

FIG. 1

;

FIG. 6

is a plan view of the cartridge changer of

FIG. 5

;

FIG. 7

is a left-hand side view of the cartridge changer of

FIG. 5

;

FIG. 8

is an enlarged vertical sectional view of a paint replenisher shown in

FIG. 1

;

FIG. 9

is a vertical sectional view of the paint replenisher in an operational stage of replenishing a paint cartridge;

FIG. 10

is an enlarged schematic view of a cartridge gripper shown in

FIG. 7

;

FIG. 11

is a schematic illustration explanatory of a coating operation by the coating apparatus;

FIG. 12

is a schematic illustration explanatory of an operation of picking up a replenished paint cartridge from the paint replenisher;

FIG. 13

is a schematic illustration explanatory of an operation of locating the coating apparatus to a cartridge changing position by the cartridge changer;

FIG. 14

is a schematic illustration explanatory of an operation of washing the rotary atomizing head and a fore end portion of a feed tube by an atomizing head washer;

FIG. 15

is a schematic illustration explanatory of an operation of dismantling an empty paint cartridge from the coating apparatus;

FIG. 16

is a schematic illustration explanatory of an operation of positioning a replenished paint cartridge over the coating apparatus;

FIG. 17

is a schematic illustration explanatory of an operation of mounting the replenished paint cartridge on the coating apparatus;

FIG. 18

is a schematic illustration explanatory of an operation of returning a dismantled empty paint cartridge to the paint replenisher; and

FIG. 19

is an operational time chart of the cartridge changer.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, the automatic coating apparatus according to the present invention is described more particularly by way of its preferred embodiments with reference to

FIGS. 1 through 19

of the accompanying drawings.

In the drawings, indicated at

1

is a coating robot employed as a working mechanism. The coating robot

1

is largely constituted by a base

2

, a vertical arm

3

which is rotatably and pivotally supported on the base

2

, a horizontal arm

4

which is pivotally connected to a fore end portion of the vertical arm

3

, and a wrist

5

which is provided at a fore distal end of the horizontal arm

4

.

Indicated at

11

is a rotary atomizing head type coating apparatus (hereinafter referred to simply as “coating apparatus

11

” for brevity) which is mounted on the coating robot

1

. As shown in

FIG. 2

, the coating apparatus

11

is largely constituted, as described in greater detail hereinafter, by a housing

12

, feed tube passage holes

17

and

24

, a coating machine

18

, a paint cartridge

25

, a paint valve

35

, and a thinner valve

43

.

Indicated at

12

is the housing which is formed of engineering plastics such as PTFE, PEEK, PEI, POM, PI, PET and the like, and which is detachably attached to the fore end of the wrist

5

. The housing

12

constitutes a cartridge mount portion along with the coating machine

18

, and includes a neck portion

13

, which is detachably attached to the distal end of the wrist

5

of the coating robot

1

, and a head portion

14

which is formed integrally at the fore end of the neck portion

13

.

In this instance, the housing

12

is provided with a coating machine mount portion

15

and a cartridge mount portion

16

, each in the form of a cylindrical cavity, on the front and rear sides of the head portion

14

, respectively. Further, female and male coupling portions

16

B and

16

C are provided separately at the bottom

16

A of the cartridge mount portion

16

for fitting engagement with male and female coupling portions

26

A and

26

B which are provided on the side of a container

26

as will be described hereinafter. The female and male coupling portions

16

B and

16

C on the cartridge mount portion

16

function to orient the container

26

into position in the circumferential direction as the container

26

is mounted on the cartridge mount portion

16

.

Indicated at

17

is the feed tube passage hole which is provided on the side of the housing and formed between and in communication with the coating machine mount portion

15

and the cartridge mount portion

16

. This feed tube passage hole

17

on the side of the housing is composed of a front portion in the form of a feed tube passage portion

17

A of a small diameter and a rear portion in the form of a conically converging portion

17

B. In this instance, the feed tube passage portion

17

A is formed in coaxial relation with the feed tube passage hole

24

which is provided on the side of the coating machine as will be described hereinafter. On the other hand, the conically converging portion

17

B is brought into abutting and fitting engagement with a conical projection

27

which is provided on the side of the paint cartridge

25

as will be described hereinafter, for orienting the paint cartridge into position in both axial and radial directions.

Indicated at

18

is the coating machine which is set in the coating machine mount portion

15

of the head portion

14

. In this instance, the coating machine

18

is largely constituted by an air motor

19

including a motor case

19

A, rotational shaft

19

B, air turbine

19

C and air bearing

19

D, a rotary atomizing head

20

to be put in rotation by the air motor

19

for centrifugally atomizing supplied paint into finely divided particles and spraying same toward a coating object

106

which will be described hereinafter, and a shaping air ring

21

which is provided on the front side of the air motor

19

.

On the other hand, as shown in

FIG. 3

, the rotary atomizing head

20

is constituted by: a bell cup

20

A which is formed in a bell-like shape; a circular disk-like hub member

20

B which is fitted in a center portion on the front side of the bell cup

20

A; a paint spreading surface

20

C which is formed on outer peripheral portions on the front side of the bell cup

20

A for spreading paint in a thin film; a paint reservoir

20

D which is defined on the rear side of the hub member

20

B, a plural number of wash fluid inlet holes

20

E which are formed in center portions of the hub member

20

B to let a wash fluid to flow into the paint reservoir

20

D from the front side of the hub member

20

B; and a large number of paint outlet holes

20

F which are formed in outer peripheral portions of the hub member

20

B to guide paint, which is spurted out from the feed tube

28

, toward the above-mentioned paint spreading surface

20

C.

The shaping air ring

21

is bored with a multitude of shaping air outlet holes

21

A on its outer peripheral side for spurting shaping air toward paint releasing edges of the rotary atomizing head

20

to shape released paint particles into a predetermined spray pattern.

Designated at

22

is a high voltage generator which is provided on the neck portion

13

of the housing

12

. For example, the high voltage generator

22

is constituted by a Cockcroft circuit which is adapted to elevate a source voltage from a power supply (not shown) to a high voltage of from −60 kv to −120 kv. The output side of the high voltage generator

22

is connected, for example, to the air motor

19

to apply a high voltage to the rotary atomizing head

20

through the rotational shaft

19

B of the air motor

19

for directly charging paint particles.

Indicated at

23

are a plural number of air passages which are provided on the neck portion

13

of the housing

12

and are connected from a control air source (not shown), for supplying turbine air, bearing air and brake air to be supplied to the air motor for the control thereof, in addition to shaping air to be supplied to the shaping air ring for shaping the paint spray pattern. In the drawings, only one air passage is shown to represent various air passages just mentioned.

Indicated at

24

is the feed tube passage hole which is provided on the side of the coating machine, axially through the rotational shaft

19

B of the air motor

19

. This feed tube passage hole

24

on the side of the coating machine has its base end opened into a feed tube passage portion

17

A of the feed tube passage hole

17

on the side of the housing and its fore end opened into the paint reservoir

20

D of the rotary atomizing head

20

. Further, the feed tube passage hole

24

on the side of the coating machine is formed in coaxial relation with the feed tube passage portion

17

A of the feed tube passage hole

17

on the part of the housing. The feed tube

28

of the paint cartridge

25

is extractably passed into these feed tube passage holes

17

and

24

.

Denoted at

25

a,

25

b,

. . .

25

n

are paint cartridges of different colors (hereinafter referred to simply as “cartridges

25

” for brevity) which are filled with paint of different colors a, b, . . . n to be supplied to the rotary atomizing head

20

. As shown in

FIG. 4

, each one of these cartridges

25

is largely constituted by a container

26

, a conical projection

27

which is provided at a front end of the container

26

, a feed tube

28

which is extended out axially forward from the conical projection

27

, a piston

29

which is fitted in the container

26

, and a thinner passage

32

which is provided on the side of the paint cartridge to supply therethrough thinner as a paint extruding liquid.

The container

26

of the paint cartridge

25

is formed of engineering plastics, for example, similar to the housing

12

, and provided with a cylindrical body (a cylinder) of a diameter which can be removably fitted in the cartridge mount portion

16

on the housing. Further, the container

26

is provided with male and female coupling portions

26

A and

26

B on its front end face in confronting positions relative to the female and male coupling portions

16

B and

16

C on the side of the cartridge mount portion

16

, respectively. The container

26

is closed at its base or rear end, and provided with a knob

26

C of an outwardly diverging shape integrally at the rear end. This knob

26

C is adapted to be gripped by a cartridge gripper

100

which will be described in greater detail hereinafter.

The above-mentioned male and female coupling portions

26

A and

26

B serve to orient the container

26

into position in the circumferential direction when the latter is set in the cartridge mount portion

16

. These male and female coupling portions

26

A and

26

B also serve to orient the container

26

into position in the circumferential direction when the container is set on a container support portion

61

of a paint replenisher

55

which will be described hereinafter.

Indicated at

27

is a conical projection which is formed integrally at the fore end of the container

26

. This conical projection

27

is brought into abutting and fitting engagement with the conically converging portion

17

B when the container

26

of the paint cartridge

25

is set in the cartridge mount portion

16

of the housing

12

, for orienting the container

26

into position in both axial and radial directions. Also, the conical projection

27

is brought into abutting and fitting engagement with the inwardly converging conical portion

60

A which is formed on a feed tube passage hole

60

on the side of the replenishing stool, when the paint cartridge

25

is set in a container support portion

61

of a paint replenisher

55

, for orienting the container of the paint cartridge

25

into position in both axial and radial directions.

The feed tube

28

which is provided at the distal end of the conical projection

27

is internally provided with a coaxial paint supply passage

28

A, which has its base end connected to a paint reservoir chamber

30

, which will be described hereinafter, and has its fore end opened toward the rotary atomizing head

20

. Further, provided on the inner periphery of a fore end portion of the feed tube

28

is a valve seat

28

B which is formed by reducing the diameter of part of the above-mentioned paint supply passage

28

A. A valve member

35

B of the paint valve

35

, which will be described hereinafter, is seated on and off the valve seat

28

B. The feed tube

28

is arranged in such a length that its fore end is extended into the rotary atomizing head

20

when the paint cartridge

25

is set in position within the cartridge mount portion

16

.

In this instance, the feed tube

28

allows paint to flow into the paint supply passage

28

A from the paint reservoir chamber

30

and to flow out toward the rotary atomizing head

20

from the fore distal end of the paint supply passage

28

A. Further, at the time of replenishing paint into the paint reservoir chamber

30

, the fore distal end of the feed tube

28

is connected to a connector member

63

of a paint replenisher to serve as a replenishing port for the cartridge.

On the other hand, the piston

29

is axially slidably fitted in the container

26

to divide the internal space of the container

26

into a paint reservoir chamber

30

, which is in communication with the paint supply passage

28

A of the feed tube

28

, and a thinner chamber

31

to which thinner is supplied as a paint extruding liquid.

Indicated at

32

is a thinner passage on the side of the paint cartridge, the thinner passage

32

being extended axially through an outer peripheral portion of the container

26

and having one end opened in the distal end face of the male coupling portion

26

A of the container

26

and the other end communicated with the above-mentioned thinner chamber

31

. As thinner is supplied to the thinner chamber

31

through this thinner passage

32

on the side of the paint cartridge, the piston

29

is pushed toward the feed tube

28

thereby to extrude paint in the paint reservoir chamber

30

toward the rotary atomizing head

20

.

In this regard, thinner to be employed as a paint extruding liquid should be of a type which has electrically insulating properties or high electric resistance, in order to prevent the high voltage from the high voltage generator

22

from leaking through thinner. In case thinner is used as an extruding liquid, it contributes to retain inner wall surfaces of the container

26

always in a wet state as the piston

29

is displaced within the container

26

, preventing paint from getting dried up and solidifying on the inner wall surfaces and stabilizing frictional resistance between the piston

29

and the inner wall surfaces of the container

26

to ensure smooth movement of the piston

29

. Besides, it also contributes to enhance the tightness of the seal between the piston

29

and inner wall surfaces of the container

26

.

Indicated at

33

is a quick coupling which is provided within the male coupling portion

26

A of the container

26

, at an open end of the thinner passage

32

on the side of the paint cartridge. When the paint cartridge

25

is set in position within the cartridge mount portion

16

, bringing the male coupling portion

26

A into engagement with the female coupling portion

16

B, a valve in the quick coupling

33

is opened to communicate the thinner passage

32

on the side of the cartridge with the thinner passage

39

on the side of the housing which will be described hereinafter. On the other hand, when the container

26

is removed from the cartridge mount portion

16

, thereby disengaging the male coupling portion

26

A from the female coupling portion

16

B, the thinner passage

32

on the side of the paint cartridge is closed by the action of a valve spring to prevent thinner from flowing out of the thinner passage

32

. Also, the opening and closing operations of the quick coupling

33

are performed in case of loading or unloading the paint cartridge to the container support portion

61

of the replenishing stool

56

which will be described hereinafter.

Indicated at

34

is a paint valve accommodating portion which is provided in a front end portion of the container

26

, and at

35

a paint valve which is received in the paint valve accommodating portion

34

. In this instance, the paint valve

35

is constituted by an air-piloted directional control valve, including a piston

35

A which is slidably fitted in the paint valve accommodating portion

34

in such a way as to define a spring chamber and a pressure receiving chamber on its opposite sides, an elongated valve member

35

B which is connected to the piston

35

A at its base end and extended into the paint supply passage

28

A of the feed tube

28

at its fore end to seat on and off the valve seat

28

B, and a valve spring

35

C which is provided in the spring chamber of the paint valve accommodating portion

34

and adapted to act on the valve member

35

B through the piston member

35

A urging the valve member

35

C to seat on the valve seat

28

B .

Normally, the valve member

35

B of the paint valve

35

is seated on the valve seat

28

B of the feed tube

28

under the influence of the biasing action of the valve spring

35

C, thereby closing the paint supply passage

28

A and suspending paint supply to the rotary atomizing head

20

. On the other hand, as soon as pilot air is supplied to the pressure receiving chamber in the paint valve accommodating portion

34

from a pilot air source through a pilot air piping system (both not shown) via the pilot air passage

38

on the side of the housing and the pilot air passage

36

on the side of the paint cartridge, the valve member

35

B is unseated from the valve seat

28

B against the action of the valve spring

35

C to start supply of paint from the paint reservoir chamber

30

to the rotary atomizing head

20

. In this instance, one end of the pilot air passage

36

is opened in an inner peripheral surface of the female coupling portion

26

B of the container

26

, while the other end is communicated with the pressure receiving chamber of the paint chamber

34

.

Indicated at

37

is a thinner passage which is provided on the side of the housing

12

. The thinner passage

37

is extended axially through and within the neck portion

13

and bent backward in an L-shape at a position behind the female coupling portion

16

B. One end of this thinner passage

37

on the side of the housing is connected to a thinner supply device (not shown), while the other end is opened in a bottom portion of the female coupling portion

16

B on the cartridge mount portion

16

. The angularly bent portion of the thinner passage

37

on the side of the housing is arranged to provide a valve seat

37

A for seating and unseating a valve member

43

B of a thinner valve

43

which will be described hereinafter.

Denoted at

38

is a pilot air passage which is provided on the side of the housing

12

. One end of this pilot air passage

38

is connected to a paint valve pilot air source through pilot air piping (both not shown). The other end of the pilot air passage

38

is opened in a circumferential surface of the male coupling portion

16

C, which is provided at the bottom

16

A of the cartridge mount portion

16

, at a position which confronts the pilot air passage

36

on the side of the paint cartridge.

Indicated at

39

is an air suction passage which is provided in the housing

12

and opened in the bottom portion

16

A of the cartridge mount portion

16

. This air suction passage

39

is connected to a vacuum source through vacuum piping (both not shown). This air suction passage

39

functions to suck air out of a vacuum space

40

, which is formed at a deep portion of the cartridge mount portion

16

on the inner side of the container

26

, to fix the paint cartridge

25

in the cartridge mount portion

16

with suction force.

Further, indicated at

41

is an ejection air supply passage which is provided in the housing

12

and opened at the bottom

16

A of the cartridge mount portion

16

. This ejection air supply passage

41

is connected to an ejection air source through air piping (both not shown). Through this ejection air passage

41

, ejection air supplied to the vacuum space

40

to cancel the suction grip on the paint cartridge

25

, thereby permitting to dismantle the paint cartridge

25

from the housing.

Indicated at

42

is a thinner valve accommodating portion which is provided in the head portion

14

of the housing

12

, and at

43

a thinner valve which is provided in the thinner valve accommodating portion

42

. In this instance, substantially in the same manner as the paint valve

35

, the thinner valve

43

is arranged as an air-piloted directional control valve, including a piston

43

A which is slidably fitted in the thinner valve accommodating portion

42

in such a way as to define a spring chamber and a pressure receiving chamber on its opposite sides, a valve member

43

B which is connected to the piston

43

A at its base end and extended into the thinner passage

37

on the side of the housing at its fore end to be seated on and off the valve seat

37

A, and a valve spring

43

C which is provided in the valve chamber of the thinner valve accommodating portion

42

and adapted to act on the valve member

43

B through the piston

43

A, urging the valve member

43

B into a seated position.

Normally, the valve member

43

B of the thinner valve

43

is seated on the valve seat

37

A in the thinner passage

37

on the side of the housing under the influence of the biasing action of the valve spring

43

C, thereby closing the thinner passage

37

to suspend thinner supply to the thinner chamber

31

. On the other hand, as soon as pilot air is supplied to the pressure receiving chamber from the thinner valve pilot air source via pilot air piping (both not shown) and through the pilot air passage

44

, the valve member

43

B is unseated from the valve seat

37

A against the action of the valve spring

43

C to start thinner supply to the thinner chamber

31

. In this instance, one end of the pilot air passage

44

is connected to the thinner valve pilot air source through pilot air piping, while the other end is communicated with the pressure receiving chamber of the thinner valve accommodating portion

42

.

Referring now to

FIGS. 5

to

7

, there is shown a cartridge changer which is arranged to store a plural number of paint cartridges for different paint colors and to replaceably mount a selected one of the paint cartridges on the coating apparatus, in the manner as described below.

Namely, indicated at

51

is the cartridge changer according to the present embodiment of the invention. This cartridge changer

51

is located outside the working area of the coating robot

1

and in the vicinity of a washing apparatus

103

which will be described hereinafter. The cartridge changer

51

is largely constituted by a paint replenishers

55

, a cartridge transfer system

77

and a cartridge gripper

100

as described below.

Indicated at

52

is a deck which provides a main frame structure of the cartridge changer

51

, and which is largely constituted by four legs

53

which are erected in spaced positions in four corner portions of the rack, and a rectangular deck plate

54

which is supported on the legs

53

at its four corners and at vertically intermediate portions of the legs.

Indicated at

55

a,

55

b,

. . .

55

n

are paint replenishers for paint colors a, b, . . . n (hereinafter referred to collectively as “paint replenisher

55

” for brevity) which are provided on the rectangular deck plate

54

of the deck

52

. As shown in

FIG. 6

, the paint replenishers

55

are arranged in rows and columns. Each one of the paint replenishers

55

are largely constituted, as will be described in greater detail hereinafter, by a replenishing stool

56

, a feed tube passage hole

60

on the part of the replenishing stool, a connecting member

63

, and a replenishing valve

65

.

In this instance, the respective paint replenishers

55

are located under a longitudinal transfer mechanism

78

and a transverse transfer mechanism

86

of the cartridge transfer system

77

and outside a working area of the coating robot

1

. Paint cartridges are handed over to and from the paint replenishers

55

and the coating apparatus

11

of the coating robot

1

by the cartridge transfer system

77

, and each paint cartridge

25

is mounted into and dismantled from the housing

12

of the coating apparatus

11

by the cartridge gripper assembly

100

which is provided on a vertical lift mechanism

93

.

Designated at

56

a,

56

b,

. . .

56

n

are replenishing stools which constitute the respective paint replenishers

55

of different colors (hereinafter referred to collectively as replenishing stools

56

). As shown in

FIG. 8

, each one of the replenishing stools

56

is largely constituted by a foot portion

57

which is fixed on the deck plate

54

of the deck

52

by the use of bolts or other fixation means, a column portion

58

which is extended vertically upward from the foot portion

57

, and a seating block portion

59

which is formed by bulging an upper end portion of the column portion

58

.

Indicated at

60

is the feed tube passage hole on the side of the replenishing stool, which is formed internally of and vertically through the column portion

58

of the replenishing stool

56

to receive therein the feed tube

28

of the paint cartridge

25

. Provided at the upper end of the feed tube passage hole

60

on the part of the replenishing stool is an inwardly converging conical portion

60

A which serves to hold the container

26

in position on the replenishing stool in axial and radial direction, by coupling engagement with the conical projection

27

at the fore end of the container

26

.

Indicated at

61

is the container support portion which is provided at one axial end (on the upper side) of the seating block portion

59

to support the container

26

of the paint cartridge

25

therein. This container support portion

51

is in the form of a recessed cylindrical cavity in communication with the upper open end of the feed tube passage hole

60

on the side of the replenishing stool. As seen in

FIG. 9

, female and male connector portions

61

B and

61

C are separately formed at the bottom

61

A of the container support portion

61

for fitting engagement with the male and female coupling portions

26

A and

26

B on the part of the container

26

, respectively. These female and male connector portions

61

B and

61

C serve to set the container

26

in a predetermined position in the circumferential direction when the container

26

is mounted on the container support portion

61

.

Indicated at

62

is a connector receptacle bore which is formed in an axially opposite end portion of the replenishing stool

56

, at a deeper position than the feed tube passage hole

60

. Namely, the connector receptacle bore

62

is in the form of a cylindrical cavity which is formed by widening the diameter of a deeper portion of the feed tube passage hole

60

. The lower end of the connector receptacle bore

62

is reduced in diameter in the downward direction through a stepped portion

62

A.

Denoted at

63

is a connector member which is vertically movably provided in the connector receptacle bore

62

. The connector member

63

is formed in the shape of a tube, which internally defines a paint passage

63

A and which is provided with a flange-like spring seat

63

B of an increased diameter at the upper end thereof. The paint passage

63

A of the connector member

63

is brought into liquid-tight fitting engagement with a fore end portion of the feed tube

28

at the time of supplying paint into the container

26

through the feed tube

28

. Further, the paint passage

63

A is connected to a replenishing valve

65

through a hose

67

as will be described hereinafter.

Indicated at

64

is a coil spring which is provided around the outer periphery of the connector member

63

. More particularly, the coil spring

64

is interposed between the spring seat

63

B of the connector member

63

and the stepped portion

62

A of the connector receptacle bore

62

to bias the connector member

63

in the upward direction toward the feed tube passage hole

60

on the side of the replenishing stool.

Thus, the connector member

63

is movable vertically in the upward and downward directions, and constantly urged toward the feed tube

28

by the biasing action of the coil spring

64

. Therefore, even if the feed tube

28

is located in a deviated position in the upward or downward direction, the positional deviation of the feed tube

28

can be absorbed by an upward or downward movement of the connector member

63

. Besides, by the action of the coil spring

64

, the feed tube

28

can be securely brought into fitting engagement with the connector member

63

.

Indicated at

65

is a replenishing valve which is connected to the connector member

63

. The replenishing valve

65

is connected to a paint supply line (not shown) of a paint source on its upstream side through a paint conduit

66

. The downstream side of the paint replenishing valve

65

is connected to the connector member

63

through a flexible paint hose

67

which constitutes a paint supply passage. The replenishing valve

65

is normally closed, and opened at the time of paint replenishment to a paint cartridge

25

, permitting paint from the paint supply line to flow toward the connector member

63

.

Indicated at

68

is a thinner discharge passage which is provided in the seating block portion

59

of the replenishing stool

56

. This thinner discharge passage

68

is opened at one end thereof into the female coupling portion

61

B of the container support portion

61

, and connected at the other end to a thinner reservoir tank (not shown) through a thinner conduit

69

. Through the thinner discharge passage

68

, the thinner which flows out of the thinner chamber

31

of the paint cartridge

25

at the time of paint replenishment is discharged to the thinner reservoir tank.

Indicated at

70

is a pilot air passage on the side of the replenishing stool, which is provided in the seating block portion

59

. One end of the pilot air passage

70

is connected to a paint valve pilot air source (not shown) through a pilot air conduit

71

. The other end of the pilot air passage

70

is opened in a circumferential surface of the male coupling portion

61

C of the container support portion

61

in a confronting position relative to the pilot air passage

36

on the side of the paint cartridge. Consequently, when the paint cartridge

25

is mounted on the container support portion

61

of the replenishing stool

56

, the pilot air passage

70

on the side of the replenishing stool is communicated with the pilot air passage

36

on the side of the paint cartridge to supply pilot air from the paint valve pilot air source to the paint valve

35

.

Indicated at

72

is an air suction passage which is provided in the seating block portion

59

and opened in a bottom portion

61

A of the container support portion

61

. This air suction passage

72

is connected to a vacuum source (not shown) through a vacuum conduit

73

. Through the air suction passage

72

, air is sucked out of a vacuum space

74

which is formed between a deep bottom portion of the container support portion

61

and the container

26

of the paint cartridge

25

, so that the paint cartridge

25

is fixedly gripped in the container support portion

61

by suction force.

Designated at

75

is an ejection air supply passage which is also provided in the seating block portion

59

and opened in a bottom portion

61

A of the container support portion

61

. This ejection air supply passage

75

is connected to an ejection air source (not shown) through an air conduit

76

. At the time of dismantling the paint cartridge

25

from the container support portion

61

, air is supplied from the ejection air passage

75

to the vacuum space

74

thereby to release the paint cartridge

25

from the paint replenisher

56

.

Indicated at

77

is a cartridge transfer system which is provided over the deck

52

to transfer a cartridge gripper unit

100

, which will be described hereinafter, in the directions of three perpendicularly intersecting axes, namely, in longitudinal, transverse and vertical directions of the deck

52

. For this purpose, the cartridge transfer system

77

is largely constituted by a longitudinal transfer mechanism

78

, a transverse transfer mechanism

86

and a vertical transfer mechanism

93

. By way of these three transfer mechanisms of the cartridge transfer system

77

, a paint cartridge

25

is transferred and handed over to and from the paint replenisher

55

and the coating apparatus

11

which is mounted on the coating robot

1

.

Designated at

78

is a first or longitudinal transfer mechanism which is mounted on top of the legs

53

of the deck

52

. In this instance, as shown in

FIGS. 5

to

7

, the longitudinal transfer mechanism

78

is largely constituted by: front and rear rail support beams

79

which are extended in parallel relation between and securely fixed on right and left legs

53

on the front and rear sides of the arrayed paint cartridges

25

of the paint replenishers

55

, respectively; a pair of longitudinal rails

80

which are provided on each one of the front and rear rail support beams

79

; a couple of sliders

81

which are mounted on the longitudinal rail support beams

79

for movements longitudinally in the rightward and leftward directions on and along the longitudinal rails

80

; a pair of pulleys

82

which are rotatably mounted on right and left end portions of each longitudinal rail support beam

79

; elongated timing belts

83

which are respectively extended in the longitudinal direction and around the pulleys

82

and securely connected to the sliders

81

at a predetermined portion; a connecting rod

84

which is extended in the transverse direction to connect the pulleys

82

on the right ends of the rail support beams

79

; and a drive mechanism

85

for moving the sliders

81

in the rightward and leftward directions along the rails

80

.

In this instance, the drive mechanism

85

includes another pulley

85

A which is mounted on the connecting rod

84

, and a drive motor

85

C which is connected to the pulley

85

A through a short timing belt

85

B.

According to the extent of rotation of the drive motor

85

C of the drive mechanism

85

, the sliders

81

of the longitudinal transfer mechanism

78

are moved through the timing belts

83

either in the rightward direction or in the leftward direction along the longitudinal guide rails

80

. As a consequence, the cartridge gripper unit

100

is moved to the right or to the left through the transverse transfer mechanism

86

and the vertical transfer mechanism

93

which are supported on the respective sliders

81

.

Indicated at

86

is the second or transverse transfer mechanism which is provided on the longitudinal transfer mechanism

78

. In this instance, the transverse transfer mechanism

86

is largely constituted by: a transverse rail support beam

87

which is extended in the transverse direction and supported on the sliders

81

of the longitudinal transfer mechanism

78

at its opposite ends; a pair of transverse guide rails

88

which are provided on the transverse rail support beam

87

; a slider

89

which is movably mounted on the transverse guide rails

88

for movements therealong; a male screw member

90

which is rotatably mounted on the transverse rail support beam

87

and extended between and along said transverse guide rails

88

; a female screw member

91

which is mounted on the slider

89

and held in threaded engagement with said male screw member

90

through a large number of steel balls (not shown) to form a ball screw together with the male screw member

90

; and a drive mechanism

92

for moving the slider

89

back and forth along the transverse guide rails

88

.

In this instance, the drive mechanism

92

is constituted by a pulley

92

A which is mounted on an end portion of the male screw member

90

, and a drive motor

92

C which is connected to the pulley

92

A through a timing belt

92

B.

According to the extent of rotation of the drive motor

92

, the male screw member

90

is turned relative to the female screw member

91

to move the slider

89

along the transverse guide rails

88

of the transverse transfer mechanism

86

. Accordingly, the transverse transfer mechanism

86

moves the cartridge gripper assembly

100

in a transverse direction through the vertical transfer mechanism

93

which is mounted on the slider

89

.

Indicated at

93

is the third or vertical transfer mechanism which is mounted on the transverse transfer mechanism

86

. In this instance, the vertical transfer mechanism

93

is largely constituted by: a post

94

which is fixedly attached to the slider

89

of the transverse transfer mechanism

86

and extended in vertical direction; a pair of vertical guide rails

95

which are provided on the post

94

; a slider

96

which is movably mounted on the vertical guide rails

95

for movements therealong; and a drive mechanism

97

for moving the slider

96

along the vertical guide rails

95

.

In this instance, the drive mechanism

97

is largely constituted by a piston-cylinder

97

A which is mounted on the post

94

and internally provided with a free piston (not shown) for sliding movements therein; and a lift member

97

B which is provided on the outer peripheral side of the cylinder

97

A and adapted to move up and down following movement of the free piston. The lift member

97

B is connected to the slider

96

. In this manner, the drive mechanism

97

is arranged as a rodless cylinder which can stop the slider

96

in predetermined upper and lower positions.

Thus, the slider

96

of the vertical transfer mechanism

93

is moved in upward and downward directions along the vertical guide rails

95

as the lift member

97

B of the drive mechanism

97

is moved along the cylinder

97

A. As a consequence, the cartridge gripper assembly

100

which is attached to the slider

96

is moved vertically in the upward or downward direction along with the slider

96

of the vertical transfer mechanism

93

.

Indicated at

98

is one shock absorber which is constituted, as shown in

FIG. 10

, by a rectangular top plate

98

A which is projected froward from the front side of the slider

96

, four rod members

98

B which are pendant from the top plate

98

A and are loosely fitted in the top plate

98

A for vertical movements relative to the latter, a bottom plate

98

C which is securely fixed to lower ends of the rod members

98

B, and coil springs

98

D which are fitted around the rod members

98

B between the top and bottom plates

98

A and

98

C. Attached to the bottom plate

98

C is one of gripper members

101

of the cartridge gripper assembly

100

.

Further, indicated at

99

is the other shock absorber which is provided side by side with the above-described one shock absorber

98

. Similarly to the first-described shock absorber

98

, the other shock absorber

99

is constituted by top plate

99

A, rod members

99

B, bottom plate

99

C and coil springs

99

D. Attached to the bottom plate

99

C is the other one

102

of the gripper members of the cartridge gripper assembly

100

.

The shock absorbers

98

and

99

are located between the vertical transfer mechanism

93

and the gripper members

101

and

102

of the cartridge gripper assembly

100

. Therefore, at the time when the grippers

101

and

102

are lowered toward and abutted against paint cartridges

25

by the vertical transfer mechanism

93

, the shock absorbers

98

and

99

permit upward displacements of the grippers

101

and

102

to buffer impacts of abutting contact. In addition, the shock absorbers

98

and

99

permit downward displacements of the grippers

101

and

102

to absorb relative positional deviations of paint cartridges

25

, if any.

The cartridge gripper assembly

100

is mounted on the vertical transfer mechanism

93

through the shock absorbers

98

and

99

as cartridge gripper means, and largely constituted by a couple of gripper members

101

and

102

to simultaneously grip a couple of paint cartridges

25

side by side.

Indicated at

101

is one of the gripper members, which is supported on the vertical transfer mechanism

93

through one shock absorber

98

. This one gripper member

101

is attached to the bottom plate

98

C of one shock absorber

98

, and largely constituted by a drive section

101

A which has an actuator (not shown) built into its housing, and a pair of gripper claws

101

B which are provided in the drive section

101

A and adapted to be moved toward and away from each other by the actuator. The gripper claws

101

B of the first gripper member

101

are moved toward or away from each other by the actuator of the drive section

101

A at the time of gripping or releasing a knob portion

26

C of a container

26

.

The other or second gripper member

102

which is provided wide by side with the first gripper member

101

is similarly constituted by a drive section

102

A which is mounted on the lower side of the bottom plate

99

C of the other shock absorber

99

, and a pair of gripper claws

102

B which are provided on the drive section

102

A.

On the other hand, indicated at

103

is a washer which is located within a working area of the coating robot

1

and in the vicinity of the cartridge changer

51

, for the purpose of washing clean the rotary atomizing head

20

. In this instance, the washer

103

is largely constituted by a waste liquid recovering container

104

to be located under the coating apparatus

11

when the coating apparatus

11

is moved to a predetermined cartridge replacing position, and washing nozzles

105

which is provided within the waste liquid recovering container

104

to spurt out a wash liquid toward the rotary atomizing head

20

in a washing step of a coating operation.

More particularly, after the coating apparatus

11

is located in a cartridge replacing position of the cartridge changer

51

and the housing

12

of the coating apparatus

11

is located within the waste liquid recovering container

104

, a wash fluid is spurted toward the front end of the rotary atomizing head

20

from the washing nozzles

105

of the washer

103

.

With the arrangements as described above, the automatic coating apparatus according to the present embodiment can perform coating and cartridge (color) changing operations automatically, in the manner as described below with reference to

FIGS. 11 through 18

and to the time chart of FIG.

19

. In the operational conditions as illustrated in FIGS.

11

through

18

, the two grippers

101

and

102

are located in overlapping positions and only one of the two grippers

101

and

102

, which is on the proximal side, is visible. However, the two grippers

101

and

102

are shown separately in these figures for the purpose of explaining movements of the respective grippers.

Firstly, in the case of a coating operation, the automatic coating apparatus is operated according to an uploaded coating program, which specifies the order of paint colors to be used in the coating operation. Therefore, concurrently with a coating operation with a first paint color, the cartridge changer

51

is operated to pick up a replenished paint cartridge

25

of a next color from the paint replenisher

55

to attain higher efficiency of cartridge replacing work.

Firstly, in a coating step, the arms

3

and

4

of the coating robot

1

are operated as shown in

FIG. 11

to turn the coating apparatus

11

with a paint cartridge

25

a

of color a, for example, toward a coating object

106

. In this state, the air motor

19

is actuated, thereby putting the rotary atomizing head

20

in high speed rotation, spurting out shaping air through the shaping air outlet holes

21

A on the shaping air ring

21

, and applying a high voltage to the paint from the high voltage generator

22

. Then, thinner is supplied as a paint extruding liquid quantitatively to the thinner chamber

31

in the container

26

, thereby pushing forward the piston

29

to supply the paint of color a from the paint reservoir chamber

30

to the rotary atomizing head

20

through the feed tube

28

. As a result, the paint is sprayed in finely atomized particles from the rotary atomizing head

20

toward the coating object

106

.

Now, in order to change to paint color from a to b, the cartridge changer

51

is operated to pick up a replenished paint cartridge

25

b

of next color bconcurrently with a coating operation with a preceding color a as mentioned hereinbefore.

In the step of picking up a replenished paint cartridge of a next color, the longitudinal and transverse transfer mechanisms

78

and

86

of the cartridge changer

51

to locate one gripper member

101

of the cartridge gripper assembly

100

, which is supported on the vertical transfer mechanism

93

, in a position over the paint cartridge

25

b

which is supported on the replenishing stool

56

b of the paint replenisher

55

b.

Then, the vertical transfer mechanism

93

is operated to lower the gripper member

101

along with the slider

96

toward the paint cartridge

25

b

and to grip the knob portion

26

C of the paint cartridge

25

b

by the gripper claws

101

B of the gripper member

101

.

When the cartridge gripper assembly

100

is lowered by the vertical transfer mechanism

93

as described above, one gripper member

101

is abutted against the paint cartridge

25

b.

At this time, however, one shock absorber

98

buffers the impacts of abutment by letting the gripper member

101

move in the upward direction. The shock absorber

98

which permits vertical upward or downward movement of the gripper member

101

also contributes to absorb a vertical positional deviation of the paint cartridge

25

b,

if any. The same applies to the other shock absorber

99

as well as the other gripper member

102

.

As soon as the paint cartridge

25

b

is gripped by one gripper member

101

, the cartridge gripper assembly

100

is lifted up by the vertical transfer mechanism

93

. As a result, the replenished paint cartridge

25

b

is picked up from the replenishing stool

56

b

by one gripper member

101

. Then, through the longitudinal and transverse transfer mechanisms

78

and

86

, the gripper member

101

which grips the replenished paint cartridge

25

b

of color b in one gripper member

101

is further transferred until the other gripper member

102

is located in a standby position over the washer

103

as shown in FIG.

12

.

A step of coating color a is followed by a washing step to wash off deposited color a from the coating apparatus

11

. For this purpose, as shown in

FIG. 13

, the coating robot

1

is operated to move the coating apparatus

11

to a position above the washer

103

, thereby putting the rotary atomizing head

20

of the coating apparatus

11

in the waste liquid recovering container

104

of the washer

103

. As a result, the coating apparatus

11

is located in a cartridge replacing position over the washer

103

.

Then, the fore end of the coating apparatus

11

on the side of the rotary atomizing head

20

is inserted into the waste liquid recovering container

104

of the washer

103

to wash the rotary atomizing head

20

clean. In this washing step, as shown in

FIG. 14

, a wash fluid is spurted out from the respective washing nozzles

105

to wash away deposited previous color a from fore end portions of the housing

12

and rotary atomizing head

20

.

As a consequence, the wash fluid which is spurted out from the wash nozzles

105

is supplied to the front side of the rotary atomizing head

20

to wash off deposited paint P

1

of color a from the paint spreading surfaces

20

C. Further, part of the wash fluid is allowed to flow into the paint reservoir

20

D through the respective wash fluid inlet holes

20

E to wash off deposited paint P

2

of color a on inner wall surfaces of the bell cup

20

A as well as deposited paint P

3

of color a on fore end portions of the feed tube

28

.

At the end of the washing step, after washing off the previous color a, air is supplied to the vacuum space

40

between the housing

12

and the paint cartridge

25

a

to cancel the suction air grip on the paint cartridge

25

a.

Following the above-described washing step is an empty paint cartridge unloading step as shown in

FIG. 15

, in which the empty paint cartridge

25

a

is unloaded from the housing

12

. More specifically, in this step, the cartridge gripper assembly

100

which grips the replenished paint cartridge

25

b

in one gripper member

101

is lowered by the vertical transfer mechanism

93

to grip the empty cartridge

25

a

on the coating apparatus

11

in the other gripper member

102

. In this state, the cartridge gripper assembly

100

is lifted up by the vertical transfer mechanism

93

as shown in

FIG. 15

to extract the empty paint cartridge

25

a

out of the housing

12

of the coating apparatus

11

by the other gripper member

102

.

After removing the empty paint cartridge

25

a

from the housing

12

in this manner, the cartridge gripper assembly

100

is moved in a transverse direction by the transverse transfer mechanism

86

as shown in

FIG. 16

to locate the replenished paint cartridge

25

b

in one gripper member

101

in a position above the cartridge mount portion

16

of the housing

12

.

The empty paint cartridge unloading step is followed by a replenished cartridge loading step as illustrated in FIG.

17

. In the replenished paint cartridge loading step, the cartridge gripper assembly

100

which still grips the empty cartridge

25

a

in the other gripper member

102

is lowered by the vertical transfer mechanism

93

. As a result, as seen in

FIG. 17

, the replenished paint cartridge

25

b

which is gripped in one gripper member

101

is fitted and set in the cartridge mount portion

16

of the housing

12

. At this time, air in the vacuum space

40

is sucked out through the air suction passage

39

to grip the paint cartridge

25

b

fixed in the housing

12

by vacuum force.

As soon as the paint cartridge

25

b

of color bis loaded in the cartridge mount portion

16

of the coating apparatus

11

, the operation advances to an empty paint cartridge returning step as illustrated in FIG.

18

. In the empty paint cartridge returning step, the empty paint cartridge

25

a

which has been unloaded from the coating apparatus

11

is returned to a replenishing stool

56

a

of the paint replenisher

55

a

as shown in FIG.

18

. At this time, the feed tube

28

of the empty paint cartridge

25

a

is placed in the feed tube passage hole

60

on the side of the replenishing stool, and its container

26

is set on the container support portion

61

of the stool. Further, a fore end portion of the feed tube

28

is fitted into the connector member

63

and therefore becomes communicable with the paint hose

67

.

In the meantime or concurrently with the empty paint cartridge returning step, a coating operation is carried out by the coating apparatus

11

which is loaded with the replenished paint cartridge

25

b

of color b. Therefore, the coating apparatus

11

with the fresh and replenished paint cartridge

25

b

is moved to a coating standby position by the coating robot

1

to start coating in color b as soon as a coating object

106

is transferred to a predetermined position.

Now, the description is directed to a paint replenishing step of the operation. In this step, paint is replenished into a cartridge immediately before a coating operation by that cartridge for the purpose of preventing separation and sedimentation of pigment components in the paint. Therefore, the timing for starting replenishment varies widely depending upon the frequency at which a particular paint color is used or other factors. In this particular embodiment, a paint replenishing operation is started by way of example at a time interval from the end of the empty paint cartridge returning step as described above.

The paint replenishing step is started by opening the replenishing valve

65

of the paint replenisher

55

a

as shown in

FIG. 9

to supply and replenish paint of color a into the container

26

of the paint cartridge

25

a

through the paint hose

67

and the paint passage

63

A of the connector member

63

and through the fore end of the feed tube

28

.

In this manner, according to the present embodiment, for example, a replenished paint cartridge

25

b

of a next color b is gripped in one gripper member

101

prior to cartridge replacement. Therefore, the replenished paint cartridge

25

b

on one gripper member

101

can be loaded on the coating apparatus

11

immediately after unloading the empty paint cartridge

25

a

from the coating apparatus

11

by the other gripper member

102

. It follows that, in replacing the paint cartridge

25

, it suffices for the cartridge transfer system

77

to reciprocate the cartridge gripper assembly

100

between the paint replenisher

55

and the coating apparatus

11

just for once each time. Therefore, it becomes possible to shorten the time period required for the cartridge replacement, and to enhance the productivity.

Besides, the cartridge changer

51

is constituted by the paint replenishers

55

a,

55

b,

. . .

55

n

which are arranged to support the paint cartridges

25

a,

25

b,

. . .

25

n

of various colors in rows and columns, the cartridge transfer system

77

which is located above the paint replenisher

55

and adapted to transfer the paint cartridge

25

in longitudinal, transverse and vertical directions, and the cartridge gripper assembly

100

which is provided on the cartridge transfer system

77

and adapted to pick up replenished and empty paint cartridges. Thus, the cartridge changer

51

has the paint cartridges

25

located efficiently in rows and columns so that it can be reduced in size and installed compactly in a small space. Besides, since the cartridge gripper assembly

100

is moved by the cartridge transfer system

77

, smaller motors can be used for the drive motors

85

C and

92

C for the purpose of cost reductions.

In addition, the cartridge changer

51

utilizes the stools

56

of the respective paint replenishers

55

as seats for the paint cartridges

25

. Therefore, when an empty paint cartridge

25

is returned to the cartridge changer

51

, it can be replenished with paint by a paint replenisher

55

without a need for a transfer, for example, to a separately located paint replenisher.

Further, the vertical transfer mechanism

93

is provided with the shock absorbers

98

and

99

on the slider

96

, so that, as the gripper members

101

and

102

of the cartridge gripper assembly

100

are lowered and abutted against the paint cartridge

25

, the impacts of abutment are buffered by the shock absorbers

98

and

99

to lessen abrasive wear or damages and to enhance the durability of contacting parts. Additionally, since the shock absorbers

98

and

99

can absorb deviations in vertical position of the cartridge

25

, the vertical transfer mechanism

93

suffices to be a two-position control type which is less costly.

Further, the washer

103

for washing the rotary atomizing head

20

of the coating apparatus

11

is located at a cartridge replacement position of the cartridge exchanger

51

, so that deposited previous color on the rotary atomizing head

20

can be washed off at the time of each cartridge replacement in such a way as to enhance working efficiency.

Although in the foregoing embodiment the rotary atomizing head type coating apparatus

11

is mounted on the coating robot

1

which is typical of working mechanisms, it is to be understood that the present invention is not limited to the particular arrangement shown. For example, the coating apparatus

11

may be mounted on a reciprocator or other working mechanisms if desired.

Further, in the foregoing embodiment, the cartridge transfer system

77

is systematically provided with transfer mechanisms for transferring the cartridge gripper assembly

100

in the longitudinal, transverse and vertical directions, including the longitudinal transfer mechanisms

78

, the transverse transfer mechanism

86

, and the vertical transfer mechanism

93

which is supported on the transverse transfer mechanism

86

. However, in this regard, it is to be understood that the present invention is not restricted to the particular arrangements shown. For example, there may be employed a modified cartridge transfer system, in which the longitudinal transfer mechanism is mounted on the transverse transfer mechanism and the vertical transfer mechanism is mounted on the longitudinal transfer mechanism.

Further, although in the foregoing embodiment thinner is employed for pushing the piston

29

in the paint cartridge

25

. However, water or other extruding liquid may be employed depending upon properties of paint or upon the type of the high voltage application system.

On the other hand, to cope with coating operations in which one and same color is coated continuously, the cartridge changer may be modified to hold two or more paint cartridges

25

for each color or for a particular color.

Industrial Applicability

As described in detail hereinbefore, the automatic coating method according to the present invention is comprised of: coating step of a coating object by a coating apparatus loaded with a replenished paint cartridge and operated through a working mechanism; a step of picking up a replenished paint cartridge of a color to be used in a next coating operation from a paint replenisher means by the use of one of gripper members of a cartridge gripper means; a step of unloading an empty paint cartridge from the coating apparatus by the use of the other one of the gripper members of the gripper means with the replenished paint cartridge still gripped in one gripper member; a step of loading the replenished paint cartridge on the coating apparatus by one gripper member of the cartridge gripper means with the empty paint cartridge on the other gripper member; and a step of returning the unloaded empty paint cartridge to a paint replenisher. Accordingly, an empty paint cartridge on the coating apparatus can be replaced by a replenished paint cartridge in an efficient manner, i.e., by reciprocating the cartridge gripper means only for once between the coating apparatus and a paint replenishing means.

Further, as described hereinbefore, the automatic coating apparatus according to the present invention employs a cartridge changer, which is comprised of: a paint replenishing means having a number of paint replenisher units for different paint colors, each adapted to support and replenish a paint cartridge of a corresponding color; a cartridge transfer means adapted to transfer paint cartridges in the directions of three perpendicularly intersecting axis; and a cartridge gripper means supported on the cartridge transfer means and adapted to grip and transfer paint cartridges between the coating apparatus and the paint replenishing means. Therefore, when the coating apparatus with an empty or consumed paint cartridge is located at a predetermined cartridge replacing position for cartridge replacement after finishing a coating operation in one color, the cartridge gripper means is moved by the cartridge transfer means to hand over a paint cartridge to and from the coating apparatus and the paint replenishing means. In addition, the empty paint cartridge is supported by and replenished with paint by the paint replenishing means in preparation for next use.

Number	Name	Date	Kind
6071346	Yamauchi et al.	Jun 2000	A
6179217	Yoshida et al.	Jan 2001	B1

Automatic coating method and apparatus

Information

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CPC

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Abstract

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Priority Claims (1)

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US Referenced Citations (2)