Method and apparatus for centrifugally dehydrating workpiece

The present application is based on Japanese Patent Applications Nos. 2001-135638, 2001-226858, 2002-33713, 2002-33714 and 2002-33715, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a centrifugal dehydrating technology for removing a liquid such as a cleaning liquid adhered to a workpiece with a substantially rectangular plane (hereafter referred to also as a pallet or the like) such as a pallet or a tray or container similar thereto by the action of a centrifugal force.

2. Description of the Related Art

Conventionally, in a case where a pallet or the like formed of a resin is centrifugally dehydrated, it has been the general practice to effect centrifugal dehydration in a horizontal state in a state in which the pallet or the like is being conveyed on a conveyor. However, there are many cases where the pallet or the like is provided with a multiplicity of ribs to increase the strength, and a multiplicity of recessed portions are formed by those ribs, so that the actual situation has been such that the cleaning liquid gathered in the recessed portions cannot be easily removed even if centrifugal dehydration is performed. Accordingly, concerning the centrifugal dehydration of the pallet, a technique has been disclosed in which the pallet is rotated in an upright state (Japanese Utility Model Publication No. Hei. 6-52973). In this case, the cleaning liquid remaining in the recessed portions can be removed efficiently. However, in the case of this conventional technique, the center is liable to be offset at the time of holding the pallet, so that there has been a problem in that if the pallet is rotated as it is, the pallet becomes unstable due to an imbalance; and there is a large danger. Due to these circumstances, the holder has tended to be complex and large in size so as to hold the pallet securely. In addition, the types of pallets are very numerous, and it has been difficult to jointly use the same apparatus for the pallets of different sizes.

SUMMARY OF THE INVENTION

The present invention has been devised in view of the above-described conventional technical situation, and its object is to provide a centrifugal dehydration apparatus for a pallet or the like which, at the time of holding the pallet or the like, makes it possible to easily locate the center of gravity of the pallet or the like on the axis of rotation and is capable of easily suppressing the runout due to the centrifugal force.

In the invention, to overcome the above-described problems, a workpiece with a substantially rectangular plane is held an a diagonal line of its substantially rectangular plane by a pair of holders which are rotated by a rotator, and the diagonal line of the workpiece is aligned with an axis of rotation. Since the center of gravity of the workpiece is generally located on its diagonal line, the center of gravity of the workpiece is located on the axis of rotation according to the above-described structure. Accordingly, in accordance with the invention, it is possible to easily suppress the runout due to the centrifugal force. It should be noted that the alignment of the diagonal line of the workpiece with the axis of rotation, which is referred to herein, is not to be construed in a strict sense, and it suffices if it is possible to suppress the runout due to the centrifugal force to such an extent as to cause no hindrance by obviating an imbalance in rotation by substantially aligning the diagonal line of the workpiece with the axis of rotation. If the pair of corner portions of the workpiece are held on its diagonal line by the pair of holders, the diagonal line of the workpiece can be easily aligned with the axis of rotation. It should be noted that the direction of rotation of the workpiece may be changed over between forward rotation and reverse rotation, or the frequency of changeover may be set to two times or more. In addition, after the workpiece is subjected to cleaning in an upright state such that one edge thereof is set as a bottom, the workpiece may be tilted such that a corner portion thereof is set as a bottom, and centrifugal dehydration may be effected in the tilted state. Furthermore, the pair of holders may be each arranged to be capable of tilting in correspondence with abutment against two adjacent edge portions with each of the corner portions located therebetween when the pair of corner portions of the workpiece are respectively held by the pair of holders, and there may be further provided a supporting mechanism for supporting the two edge portions with the corner portion of a bottom of the workpiece located therebetween and a transfer mechanism for transferring the supporting mechanism.

Incidentally, the present invention may be employed to centrifugally dehydrate a planar workpiece such as a planar pallet, however, the shape of the workpiece is not limited to this. For example, the shape of the workpiece may be rectangular solid, cube, or the like. “A workpiece with a substantially rectangular plane” may be a workpiece having a contour with a substantially rectangular plane viewed from at least one direction. This type of workpiece has at least a pair of corner portions to be held when dehydrated.

Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1

is a schematic diagram illustrating a layout concerning essential portions of an embodiment in accordance with the invention;

FIG. 2

is a front elevational view illustrating the portion of setting-up means for setting up a pallet;

FIG. 3

is a plan view illustrating the portion of the setting-up means;

FIG. 4

is a left side elevational view illustrating the portion of the setting-up means;

FIG. 5

is a partial enlarged view illustrating the setting-up means;

FIG. 6

is a front elevational view illustrating the portion of a tilting means for tilting the pallet;

FIG. 7

is a partial enlarged side elevational view illustrating the tilting means;

FIG. 8

is a front elevational view illustrating an internal structure of a dehydration chamber;

FIG. 9

is a side elevational view illustrating the internal structure as viewed from the center of the dehydration chamber;

FIG. 10

is an enlarged front elevational view of one transfer mechanism for making up a first transfer mechanism;

FIG. 11

is a plan view thereof;

FIG. 12

is a side elevational view thereof;

FIG. 13

is a front elevational view illustrating another operating state of the transfer mechanism;

FIG. 14

is a front elevational view illustrating still another operating state of the transfer mechanism;

FIG. 15

is an enlarged front elevational view of the other transfer mechanism for making up the first transfer mechanism;

FIG. 16

is a plan view thereof;

FIG. 17

is an enlarged plan view of one transfer mechanism for making up a second transfer mechanism;

FIG. 18

is an enlarged plan view of the other transfer mechanism for making up a second transfer mechanism;

FIG. 19

is a front elevational view illustrating the portion of a centrifugal dehydration means;

FIG. 20

is an enlarged vertical cross-sectional view of a lower holding means for holding a lower corner portion of the pallet;

FIG. 21

is a cross-sectional view taken along line A—A of

FIG. 20

; and

FIG. 22

is an enlarged vertical cross-sectional view illustrating an upper holding means for holding an upper corner portion of the pallet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, a description will be given of an embodiment of the invention.

FIG. 1

is a schematic layout drawing illustrating a layout concerning essential portions of an embodiment in accordance with the invention. Pallets

1

as workpieces are accommodated in a magazine

2

in a horizontally stacked state, and are conveyed to setting-up means

4

one by one through a discharge conveyor

3

. The pallet

1

conveyed to the setting-up means

4

is made set up such that a mounted surface becomes vertical with its one edge as a bottom, and is mounted on a carrying-in conveyor

5

in an upright state. The pallet

1

mounted on the carrying-in conveyor

5

is conveyed to a cleaning chamber

6

in the upright state, and the cleaning of the pallet

1

is effected as a cleaning fluid is sprayed to its both obverse and reverse surfaces through cleaning nozzles

7

and

8

serving as cleaning means disposed movably on both sides of the cleaning chamber

6

. Further, the respective side surfaces of the pallet

1

are also cleaned by using the cleaning nozzles

7

and

8

and unillustrated other cleaning nozzles. It should be noted that, in the conveyance of the pallet

1

to the cleaning chamber

6

; irrespective of its size and shape, the pallet

1

is stopped such that a foremost portion of the pallet

1

is aligned with a reference position, and cleaning processing is carried out as the cleaning nozzles

7

and

8

are lowered from an upper edge portion while being reciprocally moved back and forth, for instance, by using the reference position as a reference. Further, it is possible to adopt a form in which cleaning is effected by vertically moving the cleaning nozzles

7

and

8

while the pallet

1

is being conveyed by the carrying-in conveyor

5

without being stopped. As the cleaning liquid, it is possible to use tap water, tap water with a detergent added thereto, a gas-liquid mixed solution in which a gas is mixed in a liquid, or in a case where the contamination is heavy, a liquid in which a cleaning liquid is heated or a liquid in which a particulate substance is mixed. In addition, it is possible to adopt a form in which rinsing cleaning is added after cleaning by a detergent. After cleaning, the cleaned pallet

1

as it is in the upright state is conveyed to a dehydration chamber

9

. The pallet

1

conveyed to the dehydration chamber

9

is tilted with its one corner as a bottom by a tilting means (which will be described later) when the pallet

1

is lifted up from the carrying-in conveyor

5

. The pallet

1

as it is in the tilted state is transferred to a centrifugal dehydration means

10

, and liquid drops adhered to the pallet

1

are subjected to centrifugal dehydration. Upon completion of the centrifugal dehydration, the pallet

1

as it is in the tilted state is conveyed to a carrying-out conveyor

11

, and after its tilted state is restored to the upright state with its one edge as a bottom, the pallet

1

mounted on the carrying-out conveyor

11

. The pallet

1

after being subjected to centrifugal dehydration and mounted on the carrying-out conveyor

11

is conveyed as it is in the upright state to an inverting means

12

. After being inverted to a horizontal state by the inverting means

12

, the pallets

1

are carried out in a stacked state or one by one by means of a pallet stocker

13

or the like. It should be noted that, in terms of the form of their use, the setting-up means

4

and the inverting means

12

differ from each other in that the pallet

1

in the horizontal state is made set up or the pallet

1

in the upright state is inverted to the horizontal state, but similar mechanisms are used as inverting mechanisms.

Incidentally, the planar pallet

1

is dehydrated according to the embodiment, however, a workpiece to be dehydrated is not limited to this. For example, the shape of the workpiece may be rectangular solid, cube, or the like. In the workpiece, a multiplicity of ribs and a multiplicity of recessed portions are provided.

Next, a description will be given of the respective above-described component parts. First, a description will be given of the aforementioned setting-up means

4

.

FIG. 2

is a front elevational view illustrating the portion of the setting-up means

4

,

FIG. 3

is a plan view,

FIG. 4

is a left side elevational view, and

FIG. 5

is a partial enlarged view thereof. The setting-up means

4

comprises as its principal elements lower-portion supporting members

14

and

15

spaced apart in parallel for supporting the underside of the pallet

1

as well as upper-portion supporting members

16

and

17

spaced apart in parallel in a direction perpendicular to the lower-portion holding members

14

and

15

. The arrangement provided is such that each of the pallets

1

conveyed one by one from the magazine

2

is inserted between the lower-portion holding members

14

and

15

, on the one hand, and the upper-portion supporting members

16

and

17

, on the other hand, and is set up. The upper-portion supporting members

16

and

17

are connected and fixed to the lower-portion holding members

14

and

15

by means of connecting members

18

and

19

in a state in which an interval allowing the pallet

1

to be inserted is provided therebetween. The upper-portion supporting members

16

and

17

are connected to each other by connecting members

20

and

21

. In addition, a retaining plate

22

is attached to the upper-portion supporting member

17

, and a lower end of the retaining plate

22

is set so as to jut out into, an insertion space for the pallet

1

, as shown in

FIG. 4

, in order to retain an end face of the pallet

1

. As shown in

FIG. 3

, the lower-portion holding members

14

and

15

are pivotally secured to a supporting shaft

25

by means of supporting plates

23

and

24

, respectively. In addition, the lower-portion holding members

14

and

15

are connected and fixed to each other by a connecting member

26

, and cylinders

27

and

28

for driving are installed at appropriate positions on the lower-portion holding members

14

and

15

or the connecting member

26

. It should be noted that reference numeral

29

in

FIG. 4

denotes a reinforcing plate disposed between the connecting members

18

and

19

, on the one hand, and the upper-portion supporting members

16

and

17

, on the other hand.

As shown in

FIG. 3

, the discharge conveyor

3

extends to a position below the setting-up means

4

and is disposed so as to be located between the lower-portion holding members

14

and

15

. As such, when the pallets

1

accommodated in the magazine

2

are conveyed one by one to the setting-up means

4

by means of the discharge conveyor

3

, the pallet

1

is inserted between the lower-portion holding members

14

and

15

, on the one hand, and the upper-portion supporting members

16

and

17

, on the other hand, and a leading end portion in the advancing direction is retained by the retaining plate

22

and stops at its home position. Subsequently, as shown in the partial enlarged view in

FIG. 5

, if the cylinders

27

and

28

are driven to cause their output shafts

30

to project, the lower-portion holding members

14

and

15

are rotated upward about the supporting shaft

25

through connecting pins.

31

. Consequently, the pallet

1

inserted between the lower-portion holding members

14

and

15

and the upper-portion supporting members

16

and

17

is set up on the carrying-in conveyor

5

in a state in which one edge on the side retained by the retaining plate

22

is set as its bottom. Then, the pallet

1

mounted on the carrying-in conveyor

5

in the upright state is moved out from a gap portion

32

formed on the side of distal end portions of the upper-portion supporting members

16

and

17

, as shown in

FIG. 4

, and is conveyed as it is in the upright state to the cleaning chamber

6

. In the cleaning chamber

6

, a cleaning liquid is sprayed onto both obverse and reverse surfaces from the cleaning nozzles

7

and

8

disposed movably on both sides of the cleaning chamber

6

, thereby effecting cleaning. Subsequently, the pallet

1

is conveyed as it is in the upright state from the cleaning chamber

6

to the dehydration chamber

9

. At the time of this conveyance, the lower-portion holding members

14

and

15

and the upper-portion supporting members

16

and

17

function as guides and prevents the tilting down of the pallet

1

. In addition, the pallet insertion interval formed between the upper-portion supporting members

16

and

17

and the lower-portion holding members

14

and

15

is made to be used jointly for varying sizes of the pallets

1

, and permits to set up all the subject pallets. It should be noted that sealing means is provided at an inlet and an outlet of the cleaning chamber

6

, as required, so as to prevent the scattering of the cleaning liquid to the outside.

Next, a description will be given of a tilting means for tilting the pallet

1

by using one corner as a bottom when the pallet

1

conveyed to the dehydration chamber

9

is lifted up from the carrying-in conveyor

5

, as well as a first transfer mechanism for transferring the pallet

1

as it is in the tilted state to the centrifugal dehydration means

10

and a second transfer mechanism for transferring the dehydrated pallet

1

as it is in the tilted state from the centrifugal dehydration means

10

to the carrying-out conveyor

11

for carrying out.

FIG. 6

is a front elevational view illustrating the tilting means for tilting the pallet

1

,

FIG. 7

is a partial enlarged side elevational view thereof. As shown in

FIG. 6

, disposed at a predetermined position on the conveying surface of a chain conveyor

36

having, for example, two endless chains juxtaposed and trained between a pair of sprockets

34

and

35

for making up the carrying-in conveyor

5

is a tilting means

39

having a retaining portion

37

by which a front end portion of the pallet

1

conveyed by the chain conveyor

36

and a lower-edge supporting portion

38

formed integrally with and perpendicularly to the retaining portion

37

to support the lower edge of the pallet

1

. This tilting means

39

rotatably supports the pallet

1

by a supporting shaft

40

so as not to interfere with the motion of the chain conveyor

36

, and a distal end of its drive arm

41

is rotatably connected to an output shaft

43

of a cylinder

42

for driving. As such, when the pallet

1

being conveyed on the conveying surface of the chain conveyor

36

reaches the portion of the tilting means

39

, its leading end portion is first retained by the retaining portion

37

indicated by the two-dot chain line and the pallet

1

stops. Subsequently, as the cylinder

42

is driven at an appropriate timing to forwardly advance the output shaft

43

, and the tilting means

39

is thereby rotated about the supporting shaft

40

, it is possible to tilt the pallet

1

as indicated by the solid lines. At the time of this tilting, the cleaning liquid adhered to the pallet

1

drops down. In addition, since one corner of the pallet

1

is supported by this tilting means

39

, a model change due to a change of shape such as the size of the pallet

1

is not required, so that the joint use of the tilting means

39

can be made. It should be noted that, in the above process, when the pallet

1

has approached the retaining portion

37

, the arrival may be detected by a sensor, as required, and the chain conveyor

36

may be decelerated. In addition, the chain conveyor

36

may be stopped by adjusting its timing to the timing when the pallet

1

is retained by the retaining portion

37

and stops. Alternatively, the chain conveyor

36

may be stopped after the rotation of the tilting mechanism

39

, or may be kept in a constantly driven state for conveying an ensuing pallet

1

. In the drawings, reference numeral

44

denotes a drive motor for driving the chain conveyor

36

, and

45

denotes a supporting portion for rotatably supporting the cylinder

42

.

FIG. 8

is a front elevational view illustrating an internal structure of the dehydration chamber

9

, and FIG.

9

is a side elevational view illustrating the internal structure as viewed from the center of the dehydration chamber

9

. In this embodiment, as shown in

FIG. 8

, a pair of transfer mechanisms

46

and

47

making up the first transfer mechanism for lifting up the pallet

1

mounted on the tilting means

39

and set in the tilted state and for transporting the pallet

1

as it is in the tilted state to the centrifugal dehydration means

10

are disposed in both side portions on this side of the dehydration chamber

9

. In addition, as shown in

FIG. 9

, disposed on both side portions in the rear of the dehydration chamber

9

are a pair of transfer mechanisms

48

and

49

making up the second transfer mechanism for lifting up the pallet

1

for which dehydration processing by the centrifugal dehydration means

10

has been completed and which is in the tilted state, and for transferring the pallet

1

as it is in the tilted state to a tilt restoring means for restoring the pallet

1

disposed on the carrying-out conveyor

11

side from the tilted state to the horizontal state. It should be noted that the transfer mechanisms

46

and

47

making up the first transfer mechanism and the transfer mechanisms

48

and

49

making up the second transfer mechanism are arranged to move while being by supported and guided by upper and lower rails

50

to

53

laid horizontally on both side portions, respectively. In addition, as shown in

FIG. 8

, the installation height of the one transfer mechanisms

46

and

48

is set to be higher than the other transfer mechanisms

47

and

49

.

FIGS. 10

to

12

are enlarged views of the one transfer mechanism

46

for making up the first transfer mechanism.

FIG. 10

is a front elevational view,

FIG. 11

is a plan view, and

FIG. 12

is a side elevational view. In addition,

FIGS. 13 and 14

are front elevational views illustrating other operating states of the transfer mechanism

46

. As shown in

FIG. 10

, the transfer mechanism

46

has a square pipe-shaped attaching member

56

arranged to be horizontally movable along the rails

50

and

51

by means of fitting members

54

and

55

fitting slidably to the rails

50

and

51

. A rail

57

is vertically installed on this attaching member

56

, and a lifting plate

60

is liftably installed on the attaching plate by means of fitting members

58

and

59

fitting slidably to the rail

57

. This lifting plate

60

is connected by means of a connecting portion

63

to an output shaft

62

of a cylinder

61

installed on the attaching member

56

, and is arranged to be liftable as the cylinder

61

is driven. A supporting arm

65

for supporting the pallet

1

by means of a bearing

64

, as shown in

FIG. 11

, is rotatably attached to an outer surface of the lifting plate

60

. This supporting arm

65

is arranged such that after a jutting-out portion

66

jutting out horizontally along the bearing

64

is interposed, the supporting arm

65

is bent orthogonally to form a rotating arm portion

67

extending horizontally, and is then bent upward, as shown in

FIG. 10. A

supporting portion

68

for supporting an edge portion of the pallet

1

in the tilted state is provided at its distal end. It should be noted that the jutting-out portion

66

is for allowing the supporting portion

68

to jut out to a position below the pallet

1

mounted on the tilting means

39

disposed on the carrying-in conveyor

5

when the pallet

1

is lifted up. The supporting portion

68

is formed in a U-shape, and has an inclined surface

69

for abutting against the edge portion of the tilted pallet

1

and a pair of supporting pieces

70

and

71

on both sides of the inclined surface

69

, as shown in FIG.

12

. The internal width between the supporting pieces

70

and

71

is set to be wider than the thickness of the pallet

1

, so that the pallet

1

can be supported by being merely inserted between the supporting pieces

70

and

71

, and can be also used jointly for other pallets. It should be noted that, as for the supporting of the edge portions of the pallet

1

by the transfer mechanisms, stable transfer becomes possible by supporting the pallet

1

at positions as remote from the center as possible. In addition, if the inclined surface

69

is coated with a resin or the like which is capable of reducing the frictional resistance or adhesion, when the pallet

1

is supported while staggering the timing of lifting by the two moving mechanisms

46

and

47

, it is possible to smoothly proceed to a supporting state. At the same time, when the magazine

46

moves away from the pallet

1

after mounting the pallet

1

in a predetermined position, the separation of the inclined surface

69

and the edge portion of the pallet

1

can take place smoothly.

Further, a chevron-shaped drive arm

73

is rotatably attached to an outer surface of the aforementioned lifting plate

60

by means of a supporting shaft

72

, and a distal end portion of the drive arm

73

is rotatably connected via a connecting pin

78

to an output shaft

77

of a cylinder

76

which is rotatably mounted via a mounting member

75

on a mounting plate

74

secured to the outer surface of the lifting plate

60

. Furthermore, another end portion of a connecting member

80

, which is rotatably attached via a connecting pin

79

to an intermediate portion of the rotating arm portion

67

constituting a part of the supporting arm

65

, is rotatably connected via a connecting pin

81

to a bent portion at the central portion of the drive arm

73

. It should be noted that an internally threaded member

84

meshing with a feed screw shaft

83

, which is rotatably driven by a servo motor

82

, is installed on the rear surface of the attaching member

56

, and the arrangement provided is such that the horizontal movement of the transfer mechanism

46

is effected by the servo motor

82

by means of the attaching member

56

.

As for the transfer mechanism

46

arranged as described above, as shown in

FIG. 13

, when the cylinder

61

is driven to cause the output shaft

62

to project downward from the state shown in

FIG. 10

, the lifting plate

60

connected to the output shaft

62

via the connecting portion

63

is lowered while being guided by the fitting of the fitting members

58

and

59

with the rail

57

laid on the attaching member

56

, thereby downwardly moving the supporting portion

68

for the pallet

1

. In this state, as shown in

FIG. 14

, if the cylinder

76

is driven this time to retract the output shaft

77

, the chevron-shaped drive arm

73

connected to that output shaft

77

via the connecting pin

78

rotates downward about the supporting shaft

72

. Concurrently, the rotating arm portion

67

constituting a part of the supporting arm

65

is rotated downward about the bearing

64

by means of the connecting member

80

connected via the connecting pin

81

to the bent portion at the central portion of the drive arm

73

, thereby rotating the supporting portion

68

to a lower position, as shown in the drawing. As described above, the supporting portion

68

can be moved vertically by means of the lifting plate

60

by driving the cylinder

61

. In addition, the supporting portion

68

can be rotated about the bearing

64

between the horizontal position and the lower position by means of the supporting arm

65

by driving the cylinder

76

.

FIG. 15

is an enlarged front elevational view of the other transfer mechanism

47

for making up the first transfer mechanism, and

FIG. 16

is a plan view thereof. As shown, most portions of this other transfer mechanism

47

are arranged symmetrically with those of the above-described transfer mechanism

46

. Namely, this transfer mechanism

47

is merely different in that the installation position of the rails

52

and

53

is low in view of the relationship for supporting the edge portion of the pallet

1

at a lower position than that of the above-described transfer mechanism

46

as shown in

FIG. 8

, and in that the shapes of a supporting arm

85

for supporting the pallet

1

and a supporting portion

86

provided at its distal end portion are different. Concerning the other portions, since arrangements symmetrical with those of the transfer mechanism

46

are adopted, and there are no basic differences in their functions, those portions are denoted by the same reference numerals, and a description thereof will be omitted. It should be noted that, as for the supporting arm

85

, as shown in

FIG. 16

, after a jutting-out portion

87

jutting out horizontally along the bearing

64

is interposed, the supporting arm

85

is bent orthogonally to form a rotating arm portion

88

extending horizontally, and the aforementioned supporting portion

86

for supporting the edge portion of the pallet

1

in the tilted state is directly provided at a distal end of the rotating arm portion

88

. The supporting portion

86

has an inclined surface

89

which abuts against the other edge portion of the tilted pallet

1

and is oriented in the opposite direction, as well as a pair of supporting pieces

90

and

91

on both sides of the inclined surface

89

. As shown in

FIG. 15

, an internally threaded member

94

meshing with a feed screw shaft

93

, which is rotatively driven by a servo motor

92

, is installed on the rear surface of the attaching member

56

, and the arrangement provided is such that the horizontal movement of the transfer mechanism

47

is effected by the servo motor

92

.

The horizontal movement and positioning of the transfer mechanisms

46

and

47

making up the first transfer mechanism are effected by controlling the driving of the servo motors

82

and

92

. Incidentally, when a cleaned pallet

1

is carried onto the tilting means

39

installed on the carrying-in conveyor

5

, the transfer mechanisms

46

and

47

are retreated in advance to positions where they do not interfere with the carrying-in operation of the pallet

1

. After the pallet

1

is mounted on the tilting means

39

, and by timing that the pallet

1

is tilted by the cylinder

42

at a predetermined angle, the transfer mechanisms

46

and

47

are horizontally moved by the servo motors

82

and

92

, and the supporting portions

68

and

86

are jutted out to positions below the pallet

1

. In this case, the output shafts

62

of both cylinders

61

of the transfer mechanisms

46

and

47

are caused to project to set the-lifting plates

60

at their lowered positions, and the output shafts

77

of both or one of the cylinders

76

of the transfer mechanisms

46

and

47

are retracted, as required, which, in turn, cause the chevron-shaped drive arms

73

downward about the supporting shafts

72

and cause the supporting arms

65

and

85

to rotate downward about the bearings

64

by means of the connecting members

80

. In the above-described manner, the supporting portions

68

and

86

supporting the pallet

1

jut out below the pallet

1

mounted on the tilting means

39

in a state in which the supporting portions

68

and

86

are respectively set in the lower positions.

Next, in the state in which the supporting portions

68

and

86

jut out below the pallet

1

mounted on the tilting means

39

, the output shafts

77

of the cylinders

76

are caused to project to rotate both supporting arms

65

and

85

to rotate upward about the bearings

64

so as to be restored to the horizontal state. At the same time, the output shafts

62

of both cylinders

61

of the transfer mechanisms

46

and

47

are retracted to raise the lifting plates

60

. It should be noted that the driving timings of the cylinders

76

and

61

may be concurrent or may be provided with a time lag. When the supporting portions

68

and

86

are raised in the above-described manner, the lower two edge portions of the pallet

1

are respectively inserted between the supporting pieces

70

and

71

and between the supporting pieces

90

and

91

and abut against the inclined surfaces

69

and

89

; whereupon the pallet

1

is lifted upward from the tilting means

39

while the tilted state is being maintained. Subsequently, both servo motors

82

and

92

are driven to horizontally move both transfer mechanisms

46

and

47

making up the first transfer mechanism, and the pallet

1

as it is in the tilted state is transferred to a position above a lower holding means of the centrifugal dehydration means

10

. Then, the output shafts

62

of both cylinders

61

of the transfer mechanisms

46

and

47

are caused to project to lower the lifting plates

60

, and the pallet

1

as it is in the tilted state is mounted on the lower holding means of the centrifugal dehydration means

10

. The output shafts

77

of both or either one of the cylinders

76

of the transfer mechanisms

46

and

47

are retracted, as required, to rotate the drive arms

73

downward about the supporting shafts

72

and cause the supporting arms

65

and

85

to rotate downward about the bearings

64

by means of the connecting members

80

, thereby retreating the supporting shafts

68

and

86

so as not to cause a hindrance. At the same time, the upper portion of the pallet

1

is supported by an upper holding means. Subsequently, both servo motors

82

and

92

are driven to horizontally move both transfer mechanisms

46

and

47

, so that the transfer mechanisms

46

and

47

are retreated to positions where they do not interfere with the dehydration operation by the centrifugal dehydration means

10

, and remain on standby until the ensuing operation.

Next, a description will be given of the second transfer mechanism for transferring the pallet

1

after dehydration as it is in the tilted state from the centrifugal dehydration means

10

to the carrying-out conveyor

11

.

FIGS. 17 and 18

illustrate the second transfer mechanism, in which

FIG. 17

is an enlarged plan view of one transfer mechanism

48

for making up the second transfer mechanism, and

FIG. 18

is an enlarged plan view of the other transfer mechanism

40

. As shown in

FIG. 9

, these transfer mechanisms

48

and

49

making up the second transfer mechanism are horizontally moved in directions opposite to the directions of the transfer mechanisms

46

and

47

making up the first transfer mechanism, and the pallet

1

subjected to dehydration processing is delivered to a tilt restoring means

95

consisting of a mechanism similar to that of the above-described tilting means

39

and adapted to receive the pallet

1

in the tilted state, restore it to the upright state, and mount it on the carrying-out conveyor

11

. Accordingly, when delivering the pallet

1

subjected to dehydration processing to the tilt restoring means

95

, the supporting portions for supporting the pallet

1

in the transfer mechanisms

48

and

49

need to jut out in directions opposite to the directions of the transfer mechanisms

46

and

47

making up the first transfer mechanism. For this reason, as shown in

FIGS. 17 and 18

, supporting arms

96

and

97

of the transfer mechanisms

48

and

49

are arranged such that after jutting-out portions

100

and

101

jutting out horizontally in directions opposite to the cases of the transfer mechanisms

46

and

47

along bearings

98

and

99

are interposed, the supporting arms

96

and

97

are bent orthogonally to form rotating arm portions

102

and

103

extending horizontally. Further, supporting portions

104

and

105

for supporting the edge portions of the pallet

1

in the tilted state are provided at their distal ends. The transfer mechanisms

48

and

49

making up the second transfer mechanism differ from the transfer mechanisms

46

and

47

making up the first transfer mechanism in the following aspects: First, the directions in which the aforementioned supporting portions

104

and

105

jut out are different. Secondly, although, in the case of the transfer mechanisms

46

and

47

making up the first transfer mechanism, since the pallet

1

is in a state of being wet with the cleaning liquid, even if portions of contact with the edge portions of the pallet

1

are merely the inclined surfaces

69

and

89

, the supporting portions

68

and

86

can be easily separated from the pallet

1

, in the case of the second transfer mechanism, the liquid has been removed from the surfaces of the pallet

1

; and separation is difficult, it is necessary to devise a measure so that a frictional force is not applied to the portions of contact with the edge portions of the pallet

1

in the supporting portions

104

and

105

by providing rollers or the like as in shown in the drawings. In the other basic arrangements, however, there are no differences with the transfer mechanisms

46

and

47

making up the first transfer mechanism, and the transfer mechanisms

48

and

49

making up the second transfer mechanism are provided with similar functions. Incidentally, reference numeral

106

shown in

FIG. 10

denotes a servo motor for driving one transfer mechanism

48

for making up the above-described second transfer mechanism, and the arrangement provided is such that the transfer mechanism

48

is moved horizontally by means of a feed screw shaft

107

and an internally threaded member

108

which are rotatively driven by that servo motor

106

. In addition, reference numeral

109

shown in

FIG. 15

denotes a servo motor for driving the other transfer mechanism

49

for making up the above-described second transfer mechanism, and the arrangement provided is such that the transfer mechanism

49

is moved horizontally by means of a feed screw shaft

110

and an internally threaded member

111

which are rotatively driven by that servo motor

109

.

Next, a description will be given of the above-described centrifugal dehydration means

10

. As shown in

FIG. 9

, the centrifugal dehydration means

10

is disposed substantially in a central portion of the dehydration chamber

9

.

FIG. 19

is a front elevational view illustrating the portion of this centrifugal dehydration means

10

. As shown in the drawing, the centrifugal dehydration means

10

has a lower holding means

112

and an upper holding means

113

for supporting diagonal corner portions of the pallet

1

, and effects centrifugal dehydration processing while by rotating while supporting the pallet

1

in the tilted state by these holding means

112

and

113

.

FIG. 20

is an enlarged vertical cross-sectional view of the lower holding means

112

, and

FIG. 21

is a cross-sectional view taken along line A—A thereof. As shown in the drawings, the lower holding means

112

consists of a rotating shaft

116

which is rotatably supported by an apparatus frame

115

by means of a bearing

114

, as well as a corner holding portion

120

which is formed by two side plates

117

and

118

disposed on an upper portion of the rotating shaft

116

and in which an accommodating space

119

is formed into which the corner portion of the pallet

1

can be inserted between the side plates

117

and

118

. A drive wheel

121

such as a gear is secured to a lower portion of the rotating shaft

116

, which is arranged to be rotatively driven by a motor

123

with a brake by means of a toothed belt

122

or the like, as shown in FIG.

19

. Incidentally, if an arrangement is provided such that, at the time of centrifugal dehydration, the rotating direction of the rotating shaft

116

is changed over between the forward and reverse directions so as to change over the rotating direction of the pallet

1

, the arrangement is very effective in terms of the dehydration effect.

As shown in

FIGS. 20 and 21

, a substantially U-shaped connecting member

125

is secured to the upper portion of the rotating shaft

116

by means of an end plate

124

formed integrally with the rotating shaft

116

, and the corner holding portion

120

is rotatably connected to that connecting member

125

by means of connecting pins

126

and

127

on both sides. Further, resilient members

133

and

134

such as springs are disposed between the corner holding portion

120

and a supporting plate

132

attached to the connecting member

125

side, such that the resilient members

133

and

134

are respectively fitted over rods

130

and

131

pivotally secured to supporting shafts

128

and

129

passed through the corner holding portion

120

, thereby constantly urging the corner holding portion

120

so as to return to the horizontal state shown in FIG.

21

. It should be noted that, in this embodiment, as described above, the corner holding portion

120

is rotatably connected to the aforementioned substantially U-shaped connecting member

125

by using the connecting pins

126

and

127

on both sides, and the space is thereby formed into which the corner portion of the pallet

1

can be inserted between these connecting pins

126

and

127

. Thus the arrangement is provided such that the apex portion of the corner portion can be aligned with the rotational center of the corner holding portion

120

. However, it is also possible to provide an arrangement in which, as indicated by the two-dot chain lines in

FIG. 20

, by using one supporting shaft, an intermediate portion of the supporting shaft is notched into a semicircular shape, thereby allowing the apex portion of the corner portion to be aligned with the rotational center of the corner holding portion

120

. Further, supporting shafts

139

to

142

, over which cylindrical rollers

135

to

138

are respectively fitted rotatably, are installed by being passed through the corner holding portion

120

and are respectively fixed by nuts. Incidentally, the supporting shafts

139

to

142

are positioned such that an intersection between a plane connecting abutting portions of the cylindrical rollers

135

to

136

, against which the pallet

1

abut, and a plane connecting abutting portions of the cylindrical rollers

137

and

138

is aligned with the centers of the connecting pins

126

and

127

. Namely, the supporting shafts

139

to

142

are positioned such that the apex portion of the corner portion of the pallet

1

is aligned with the centers of the connecting pins

126

and

127

when the pallet

1

is supported by the cylindrical rollers

135

to

138

. It should be noted that a pressing and supporting member

143

serving as a resilient clamping means is provided on the inner side of the corner holding portion

120

to cope with a change in the thickness of the pallet

1

, as shown in

FIG. 20

, so that the pallet

1

will not become shaky in its thickness wise direction.

FIG. 22

is an enlarged vertical cross-sectional view illustrating the upper holding means

113

for holding an upper corner portion of the pallet

1

. As shown, as for the upper holding means

113

, since arrangements similar to those of the above-described lower holding means

112

are adopted except that guide plates

144

and

145

for guiding the pallet

1

are provided and that a rotating shaft

146

is supported by a bearing

147

so as to be capable of rotating in conjunction with the rotation of the pallet

1

, the component parts will be denoted by the same reference numerals and a description thereof will be omitted. Incidentally, the guide plates

144

and

145

are useful such as when the upper corner portion of the pallet

1

mounted on the lower holding means

112

and having a different size or aspect ratio, in particular, is guided into and held onto the upper holding means

113

.

The pallet

1

transferred in the tilted state to a position above the lower holding means

112

by the transfer mechanisms

46

and

47

making up the first transfer mechanism is mounted with its lower corner portion inserted in the corner holding portion

120

, and is mounted as it is in the tilted state. At this point of time, the corner holding portion

120

maintains a substantially horizontal state by virtue of the resilient action of the aforementioned resilient members

133

and

134

. In due course of time, if a supporting frame

148

or the portion of the rotating shaft

116

is lowered by an appropriate method, and the upper holding means

113

is lowered, the corner portion of the upper portion of the pallet

1

is guided into the corner holding portion

120

by the guide plates

144

and

145

. In this case, in a case where the pallet

1

is square, the upper corner portion is guided into the corner holding portion

120

in a state in which the pallet

1

remains substantially in the tilted state. However, in a case where the pallet

1

is rectangular, the upper corner portion is guided into the corner holding portion

120

while gradually changing the tilted state such that the vertical diagonal line approaches the center of rotation which connects the lower holding means

112

and the upper holding means

113

. If the upper holding means

113

is further lowered, as the edge portion of the pallet

1

and the cylindrical rollers

135

and

136

or

137

and

138

abut against each other, both corner holding portions

120

of the lower holding means

112

and the upper holding means

113

are tilted by overcoming the resiliency of the resilient members

133

and

134

to allow the edge portions of the pallet

1

and the cylindrical rollers

135

and

136

and

137

and

138

to be brought into close contact with each other. Consequently, the diagonal line of the pallet

1

is set on the rotating shaft

116

, and stable centrifugal dehydration in which the amount of runout is small becomes possible. As described above, in various component parts of this pallet cleaning apparatus, joint use of the apparatus becomes possible.

Next, a description will be given of the results of an experiment on the dehydration effect which was conducted by using the above-described centrifugal dehydration means

10

. In experiment 1, with respect to a resin-made pallet after effecting ordinary water cleaning using the above-described centrifugal dehydration means

10

, changes in the dehydration effect were examined according to the presence or absence of the changeover between forward and reverse rotation and the frequency of changeover in the case where the change over was effected alternately at 5-second intervals. Incidentally, the rotational speed of the pallet was set to. 450 rpm. However, as for the rise concerning the rotational speed of the pallet at the time of the changeover between forward and reverse rotation, it took an acceleration time of 3 seconds or thereabouts until the target of 450 rpm was reached. Table 1 shows the results of the above-described experiment 1. It should be noted that the number of drops of water in the table shows the number of drops of water counted in a case where the pallet subjected to dehydration processing was placed on corrugated cardboard, and the number of drops of water adhered to the surface of the corrugated cardboard was counted at that time. In this case, the number of drops of water in which drops of water remaining inside the pallet moved round to the pallet surface through openings or the like formed in the mounting surface was also counted. From the results of this experiment 1, it became clear that the dehydration effect can be improved substantially if the changeover between forward and reverse rotation is effected even once as compared with the case where the changeover is not effected at all. In addition, it became clear that if the frequency of changeover between forward and reverse rotation is set to two or more, it is possible to obtain substantially satisfactory dehydration results which are free of problems in the actual use in the state persisting after centrifugal dehydration. In particular, it became clear that in the case where the frequency of changeover between forward and reverse rotation is set to three or more so that the pallet is rotated at least twice each in the forward and reverse directions, even more favorable dehydration results can be obtained stably.

TABLE 1

Number of Water

Drops Attached to

Method of Rotation of Pallet

Corrugated Cardboard

State of Draining off Surface

State of Draining of Interior

No changeover

15

slightly wet state

a state in which 4 or 5 water

between Forward

drops are present in one

(F) and Reverse (R)

recessed portion on the rear

side in the forwardly

rotating direction

Changeover

F → R

8

considerably dry state

a state in which 1 or 2 water

between F and R: 1

drops are present in one

recessed portion on the front

side in the reversely

rotating direction

Changeover

F → R → F

5

substantially Dry state

a state in which water drops

between F and R: 2

are practically nil

Changeover

F → R → F → R

4

substantially Dry state

a state in which water drops

between F and R: 3

are practically nil and the

condition is more satisfactory

Changeover

F → R → F → R →

3

substantially Dry state

a state in which water drops

between F and R: 5

F → R

are practically nil and the

condition is more satisfactory

Changeover

F → R → F → R →

3

well dry state

a state in which water drops

between F and R: 9

F → R → F → R →

are practically nil and the

F → R

condition is more satisfactory

Forward: forwardly rotated for 5 seconds

Reverse: reversely rotated for 5 seconds

In experiment 2, by using the same apparatus as that of the above-described experiment 1, changes in the dehydration effect were examined in a case where the interval of changeover between forward and reverse rotation was varied in a state in which the frequency of changeover between forward and reverse rotation was set to 3 so that the pallet is rotated twice each in the forward and reverse directions. It should be noted that the rotational speed of the pallet was set to 450 rpm in the same way as in experiment 1. Table 2 shows the results of the above-described experiment 2. The number of drops of water in the table shows the number of drops of water counted in the case where the number of drops of water adhered to the surface of the corrugated cardboard was counted when the pallet subjected to dehydration processing was placed on the corrugated cardboard, in the same way as experiment 1. From the results of this experiment 2, it became clear that even if the interval of changeover between forward and reverse rotation is varied, there is not much difference in the dehydration effect in practical use. Namely, it became clear that if the frequency of changeover between forward and reverse rotation is set to an appropriate number, a more efficient dehydration effect can be obtained by setting the interval of changeover between forward and reverse rotation to a short duration.

TABLE 2

Number of Water

Drops Adhered to

Method of Rotation of Pallet

Corrugated Cardboard

Changeover between

F → R → F → R

4

forward and reverse: 3

operated for 5 seconds

each

Changeover between

F → R → F → R

4

forward and reverse: 3

operated for 10 seconds

each

Changeover between

F → R → F → R

3

forward and reverse: 3

operated for 15 seconds

each

Changeover between

F → R → F → R

3

forward and reverse: 3

operated for 30 seconds

each

In experiment 3, by using the same apparatus as that of the above-described experiment, changes in the dehydration effect were examined in the case where the rotational speed of the pallet was varied in the state in which the frequency of changeover between forward and reverse rotation was set to 3 so that the pallet is rotated twice each in the forward and reverse directions. Table 3 shows the results of the above-described experiment 3. The number of drops of water in the table shows the number of drops of water counted in the case where the number of drops of water adhered to the surface of the corrugated cardboard was counted when the pallet subjected to dehydration processing was placed on the corrugated cardboard, in the same way as experiment 1. The mark “◯” shows a state in which most of the drops of water were removed, while the mark “Δ” shows a state in which the drops of water were noticeable. From the results of this experiment 3, it became clear that if the rotational speed of the pallet is set to 350 rpm or more, a satisfactory dehydration effect can be obtained in view of both the number of drops of water remaining on the obverse surfaces and the state of draining on the side surfaces or the inner surfaces.

TABLE 3

Number of Water

Rotational

Drops Adhered

State of Draining

Speed of

to Corrugated

Obverse

Side

Inner

Pallet (rpm)

Cardboard

surface

surface

Surface

450

3

◯

◯

◯

400

3

◯

◯

◯

350

4

◯

◯

◯

300

8

Δ

◯

Δ

250

20

Δ

◯

Δ

As described above, it became clear from experiments 1 to 3 that if the changeover between forward and reverse rotation is effected even once, the dehydration effect can be improved substantially as compared with the case of no changeover. In addition, concerning the frequency of changeover between forward and reverse rotation, it became clear that if it is set to two or more, it is possible to obtain substantially satisfactory dehydration results which are free of problems in the actual use in the state persisting after centrifugal dehydration. In addition, as for the interval of changeover between forward and reverse rotation, it became clear that even if it is set to a long duration, the dehydration effect is not improved much. Accordingly, if the interval of changeover between forward and reverse rotation is set to as short a duration as possible within a range that does not impose strains on the apparatus and the like, a more efficient dehydration operation is possible. Furthermore, concerning the rotational speed of the pallet, it became clear that if it is set to 350 rpm or more, a satisfactory dehydration effect can be obtained.

In the invention, since the arrangement provided is such that the pallet or the like is rotated while being held on its diagonal line, the center of gravity of the pallet or the like is situated on the axis of rotation. Hence, the runout due to the centrifugal force can be suppressed easily and accurately. Accordingly, even if the apparatus is rotated at high speed, safety can be ensured, and the efficiency of operation can be improved. In addition, since the pair of corner portions on the diagonal line are held, the center of gravity of the pallet or the like can be easily aligned with the axis of rotation, it is possible to accurately overcome the positional offset during the rotation of the pallet or the like.

The invention is not limited at all to the description of the mode for carrying out the invention and the description of the embodiments. The invention includes various modifications that can be conceived easily by those skilled in the art, without departing from the description of the scope of claim.

Number	Date	Country
2001-226858	Jul 2001	JP
2002-033713	Feb 2002	JP
2002-033714	Feb 2002	JP
2002-033715	Feb 2002	JP

Number	Name	Date	Kind
4161356	Giffin et al.	Jul 1979	A
5104682	Nakahama et al.	Apr 1992	A
5458249	Shang-Lu	Oct 1995	A
6185834	Yang	Feb 2001	B1

Method and apparatus for centrifugally dehydrating workpiece

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (4)

US Referenced Citations (4)

Foreign Referenced Citations (1)