Process of making a coil in a length of thermoplastic tubing

BACKGROUND

Applications exist for dispensing medications by way of inhaler devices. Such devices long have been popular for use by persons with asthma to deliver vapor medications stored under pressure, through a chamber, and ultimately, to an inhaler which is placed in the mouth of the person requiring the medication. The medicine which is dispersed in asthma inhalers, however, is vaporized liquid, which is placed in a pressure dispenser associated with the inhaler. Whenever a dosage of medicine is to be delivered, a valve is momentarily opened to dispense and vaporize the stored liquid for inhalation by the user.

In recent years, experimentation has been undertaken for delivering powdered medicine by way of an inhaler. Particularly promising is the development of insulin powder which may be inhaled, thereby eliminating the need for injected insulin and all of the problems which are attendant with medications which must be injected at frequent intervals. For delivering powdered medication such as insulin powder, the inhaler device must be designed to blow a stream of compressed air through the powder, creating a cloud of tiny medication particles which then may be inhaled from the device.

The Haber U.S. Pat. No. 5,287,850 is directed to a powdered pharmaceutical inhaler mechanism. The device of this patent delivers pressurized air through a coiled tube for dispersing and driving powdered pharmaceutical into the mouthpiece for inhalation by the user. Different parts of the mechanism shown in this patent are designed to be moved from a loading position to a delivery position; and this includes the coiled tube which interconnects these parts. The movement of the tube in this device, however, is quite limited, as is readily apparent from an examination of the device shown in the patent.

For inhaler mechanisms where there is a manual pressurization of a charge of air, different parts of the mechanism need to be moved toward and away from one another a greater distance than the parts of the Haber patent. Typically, such mechanisms require movement of from one-half inch to 1½ inches in order to effect the desired charging and cocking of the mechanism. In such manual pressurization mechanisms, it is necessary to utilize a flexible tube to interconnect the charged air with the delivery portion. This tube must be capable of handling the air pressure charge, as well as extension and retraction as the device is utilized. Because there is a relatively long distance of travel between the parts in the various stages of operation, it has been found that a sufficiently long straight length of plastic tubing tends to bend and rub against other internal parts. This rubbing ultimately causes weakness in the wall of the tube, resulting in failure of the device. Because of the relatively large distance of travel in such a manual charging and cocking mechanism, it also is possible to crimp or kink the tube, which also leads to incomplete or ineffective delivery of the medication, and a failure of operation of the device.

It is desirable to provide a machine and method for forming a thermoplastic tube, with a uniform cross-sectional thickness throughout its length, as a helical spring, which can be extended and released to its thermoset, coiled, biased condition repeatedly for use in manually charged powdered medication delivery systems.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a method for forming a helical coil in a length of hollow cylindrical plastic tubing.

It is another object of this invention to provide a method for forming a helical coil in a length of hollow cylindrical plastic tubing, where the wall thickness of the tubing is uniform throughout its length, including the helical coil.

It is an additional object of this invention to provide a machine for forming a helical spring coil in a length of hollow cylindrical thermoplastic tubing.

It is a further object of this invention to provide a method and machine for forming a thermoset spring coil in a length of hollow cylindrical thermoplastic tubing.

In accordance with a preferred embodiment of this invention, a method and machine form a helical coil in a length of hollow cylindrical thermoplastic tubing. This is accomplished by clamping the ends of a predetermined length of plastic tubing between first and second opposed spaced clamping mechanisms, which may be in the form of first and second sections of a mandrel. The clamping mechanisms, or first and second mandrel sections, then are rotated relative to one another and simultaneously moved toward one another to form a helical coil in the tubing. Where first and second mandrel sections are employed, the helical coil is formed around the mandrels as they move toward one another. Once the coil is formed, the region of at least the coil portion of the tubing is heated to the thermosetting temperature of the tubing to heat-form the coil in the tubing. Following the heating to set the coil, the coil and tubing are cooled; and the spring coil tube is released from the machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a side view of a thermoplastic tube segment, which is formed into a thermoset coil by the machine of the preferred embodiment of the invention;

FIG. 2

is a side view of a completed part made by the machine of the preferred embodiment;

FIG. 3

is a cross-sectional view, taken along the line

3

—

3

of

FIG. 2

;

FIG. 4

is a perspective view of a preferred embodiment of the invention;

FIG. 5

is an exploded view of a portion of the embodiment shown in

FIG. 4

;

FIG. 6

is a cross-sectional detail of a portion of the embodiment shown in

FIGS. 4 and 5

;

FIG. 7

is a cross-sectional view taken along the line

7

—

7

of

FIG. 6

;

FIG. 8

is an enlarged detail of the portion encircled as “8” in

FIG. 6

; and

FIG. 9

is an enlarged detail of the portion shown encircled as “9” in FIG.

6

.

DETAILED DESCRIPTION

Reference now should be made to the drawings, in which the same or similar components have the same reference numbers throughout the different figures.

FIG. 1

is a side view of a short length of elongated flexible tube or conduit, which is intended to be formed into a coiled spring conduit member designed to interconnect two different parts of a powdered medicine delivery inhaler mechanism.

An inhaler device, in which the tube shown in

FIGS. 1

,

2

and

3

, is used, is subjected to air pressure of approximately 80 psi when air is released through the dispenser device and the tube

10

. The tube

10

of

FIG. 1

is formed from thermoplastic material, which may be extruded and then subsequently heat formed. Initially, extruded tubular material, having the desired internal and external diameters, is cut into the desired length; and segments

14

and

16

, at both ends, are flared by means of heat forming insert mandrels. The manner in which this is accomplished is not important to an understanding of the present invention. It is to be noted, however, that the starting material for use with the machine described subsequently is the tube

10

, shown in

FIG. 1

, with the enlarged or flared segments

14

and

16

on the ends. The flared segments are selected to have an internal diameter which is greater than the uniform internal diameter of the main body

10

of the tube, for purposes of interconnecting the finished product in an inhaler with a uniform internal diameter airflow passage throughout the length of the entire mechanism, including the portions to which the flared end segments

14

and

16

are attached.

In order to form a substantially single-turn helical coil

12

, thermoset into the shape shown in

FIG. 2

, from the straight length of tube

10

of

FIG. 1

, the machine shown in

FIGS. 4 through 9

is employed. This machine is designed to simultaneously produce six thermoset coiled spring tube members of the type shown in

FIGS. 2 and 3

with each cycle of operation. The finished product, as shown in

FIGS. 2 and 3

, is a thermoplastic tube

10

with a uniform cross-sectional thickness throughout its length. The tube is thermoset formed as a helical spring which may be extended and released repeatedly to its thermoset-biased coiled condition, for use in manually-charged, powdered medication delivery systems.

FIG. 4

is a top perspective view of the primary operating components of the machine of the preferred embodiment used to form the product shown in FIG.

2

. Some conventional mechanisms, which may be associated with the machine of

FIGS. 4 and 5

, have not been shown in order to more clearly present the features which are unique to the operation of the preferred embodiment of the invention.

Basically, the machine includes two spaced-apart parallel mounting blocks

20

and

22

, which are secured to a machine base (not shown) in any suitable manner. The blocks are spaced a uniform distance apart; and each of them includes six aligned, equally spaced support bearings for rotating mandrels. The mandrels, in turn, are supported in a pair of movable, bearing support members

24

and

26

for the blocks

20

and

22

, respectively. Six mandrels

28

extend through bearings

32

in the member

24

; and a corresponding six mandrels

30

extend through bearings

34

in the mandrel support member

26

.

As shown in both

FIGS. 4 and 5

, the mandrels

30

also slidably extend through the bearings

36

in the main support block

22

, as well. Similar bearings (not shown) in the support block

20

are used for allowing pivotal rotation of the mandrels

28

in that support block for either or both sets of mandrels

28

and

30

. The mandrel support members

24

and

26

for either or both sets of mandrels

28

and

30

are arranged to be moved toward and away from the blocks

20

and

22

, respectively, through means of a suitable electromechanical system

94

. This is diagrammatically illustrated in

FIG. 4

, by means of the dotted lines

100

and

102

interconnecting the mandrel support members

24

and

26

with a control and drive motor unit

94

.

In the operation of the machine, at the beginning of each cycle, six pre-formed plastic tube sections of the type shown in

FIG. 1

are dropped into aligned slots

62

and

83

, formed on the upper surfaces of opposite sleeves

60

and

82

, respectively, which surround the mandrels

30

and

28

, as shown most clearly in FIG.

6

. One of the pre-formed lengths of tube

10

, with the flared end segments

14

and

16

, is placed in each of these opposing sleeves in the slots on the top of the mandrels

30

and

28

, in each of the six different positions of the six-unit machine shown in FIG.

4

. Each of the different positions are identical; and one of them is diagrammatically illustrated in FIG.

6

.

FIG. 5

illustrates, in an exploded view, the portions of the sleeves and operating parts which are associated with one of the mandrels

30

. It should be noted that each of the mandrels

30

are identical, and that the corresponding parts which are associated with those mandrels are identical. For that reason, only one has been shown in exploded detail. Similarly, the mandrels

28

are surrounded with sleeves and operating collars which are identical to one another, and are identical to the one shown in exploded view in FIG.

5

. In order to avoid cluttering the drawing with unnecessary details, only one of the mandrel and sleeve sets is shown in exploded detail; and only a partial cross section of some of the operating features is shown in FIG.

6

.

When a part

10

is dropped into the slots

62

and

83

, as shown in

FIGS. 5 and 6

, the flared end rests on a wider flat portion

61

on the sleeve

60

(and a corresponding flat portion on the sleeve

82

) with the main body of the tube

10

which is located between the end segments

14

and

16

extending through the narrower slot

62

, for example, in the sleeve

60

. An identical construction on all of the other sleeves on both sides of the machine is employed; so that the tube

10

extends through the narrow slots

60

on the machine portion carried by the block

22

, and a similar set of slots

83

carried by the sleeves

82

on the block

20

.

FIG. 7

is a cross-sectional view of this portion of the machine, which illustrates the orientation of the sleeve

82

and its slot

83

, with respect to the mandrels

28

. Again, a similar cross section taken on any of the other sleeves and mandrels, on both sides of the machine, is identical to the one shown in FIG.

7

.

In order to lock the thermoplastic tube section

10

/

14

/

16

into place for effecting a subsequent rotating operation, a second sleeve is provided at each of the mandrel positions. This is a larger sleeve,

90

for the mandrels associated with the block

20

, and

54

for the mandrels

30

associated with the block

22

. The cross-sectional views of

FIGS. 6 and 7

illustrate the general orientation of the locking sleeves

90

and

54

with respect to the other parts.

After the tube section

10

of

FIG. 1

is placed in the slots on the smaller sleeves

82

and

60

, as described above, the locking sleeves

90

and

54

are rotated to cause the open gap, such as the gap

84

shown in

FIGS. 6 and 7

, to rotate over and close the opening over the top of the flanges

14

and

16

. The flanges

14

and

16

stick up just slightly above the upper diameter projection of the sleeves

60

and

82

; so that when this rotation of the sleeves

90

and

54

is effected, a vice-like clamping action is provided to tightly grip the end segments

14

and

16

in place, and hold them against any rotation of the tube

10

during the next cycle of operation of the machine.

To effect the clamping of the end segments

14

and

16

, a rectangular sliding bar assembly, including a pair of spaced-apart horizontal end members

76

and

88

, which are interconnected by elongated side members (not shown) is provided. This rack slides in facing slots

70

and

72

in the support blocks

22

and

20

, respectively, and. is operated by the control and drive motor mechanism

94

at the beginning and end of each cycle to reciprocate back and forth, as indicated by the double-ended arrow at the left-hand end of FIG.

4

. Once all of the tubes

10

are in place as described above, the rack

76

/

88

is moved toward the right, as viewed in

FIG. 4

, to cause six spaced engaging pins

78

, on the right-hand end side of the rack

76

, and a corresponding set of six engaging pins

80

on the left-hand side of the rack, to engage corresponding slots

52

and

42

located, as is most readily apparent in

FIGS. 4 and 5

, on the lower sides of circular operators

48

and

38

which are fixedly attached for rotation with the sleeves

54

and

90

, respectively. When the rack

76

/

88

moves toward the right, as seen in

FIG. 4

, the operators

48

associated with the sleeves

54

are rotated clockwise (as viewed in FIG.

5

); and the operators

38

, associated with the sleeves

90

in the support block

20

, are operated counterclockwise (as viewed in

FIG. 4

) to rotate over the openings in the ends of the slots

62

and

83

and effect the clamping of the flanges

14

and

16

, as described above. The rack

78

/

88

remains in its rightmost position for the duration of the next portion of the cycle of operation. It should be noted, however, that for the operation just described, the pins

78

and

80

engage the slots

52

and

42

, respectively, to effect the rotation. This causes a second set of slots (located 180° from the slots

42

and

52

engaged by the pins

78

and

72

) to be rotated into position for subsequent engagement for rotating the assembly back to the starting position, once a complete cycle of operation has taken place. For the purposes of the next portion of the ensuing discussion, however, it should be noted that the rack

78

/

88

moves from the position shown in

FIG. 4

toward the right (as shown in FIG.

4

), as described above, and remains there until it is time to commence a new cycle of operation.

After the flanges

14

and

16

are locked into place, the control and drive motor mechanism

94

commences rotation of the mandrels

30

, through a set of drive shafts, while the mandrels

28

remain in a fixed or non-rotating condition. At the same time, the control and drive motor

94

moves the mandrel support members

24

and

26

toward the blocks

20

and

22

, respectively, in synchronism with the rotational force applied through the drive shafts

96

to the mandrels

30

to cause a coil

12

to be formed in the center of the pre-formed cut length of thermoplastic tubing

10

of FIG.

1

. In

FIG. 2

the coil

12

is shown offset from the center, but in reality, the coil

12

will form at the center of the tube

10

because of the uniform wall thickness and strength of the material.

The movement of the mandrel support blocks

24

and

26

, toward one another, is at a rate to accommodate for the reduction in length between the ends of the tube

10

as the coil

12

is formed in it. The coil

12

forms around the path of the mandrels

28

and

30

; and in fact, as they approach one another, the coil

12

is wound around the mandrels

28

and

30

.

At the end of the rotation to form the coil

12

(chosen to be slightly more than 360° of relative rotation between the mandrels

30

and

28

), the mandrel ends

29

and

31

engage one another.

FIGS. 6

,

8

and

9

show details of this portion of the mechanism. The mandrels

28

have a slot

29

formed in their end; and the mandrels

30

have a flat projection

31

formed in the end, which mates with the slot

29

. As a consequence, when the mandrel

30

is moved into engagement with the end of the mandrel

28

, the flat projection

31

extends into the slot

29

. Continued rotation of the mandrel

30

under control of the drive motor

94

, through the shaft

96

, now causes the entire assembly of joined mandrels

30

and

28

to rotate together at the same rate. This occurs immediately after the coil is formed in the tube

10

.

During the time mandrels

28

and

30

are engaged (as indicated in dotted lines in

FIG. 6

) for rotation together, hot air at a sufficiently high temperature to exceed the thermosetting temperature characteristics of the plastic used in the tube

10

, is applied to the coils

12

through a heater

110

. The coils

12

rotate in the region of the hot air applied from the heater

110

; and this rotation in thermosetting heat is effected for a length of time sufficient to cause the thermosetting formation of the coil

12

. Once thermosetting of the coil

12

in the tube

10

has been completed, heat application from the heater

110

is discontinued. Continuous rotation of the mandrels

30

and

28

together is effected; and if desired, cooling air may be blown across each of the coils

12

in a conventional manner (not shown) to effect a more rapid cooling down of the parts. Once the parts are sufficiently cooled, the rack

78

/

88

is operated by the control and drive motor mechanism

94

, through the control link indicated in dotted lines

98

, to move back toward the left and to rotate the sleeves

54

and

90

back to the relative positions shown in

FIGS. 4

,

5

and

7

. The slots

62

and

84

once again are opened. Continued rotation of the mandrels

30

and

28

then causes the assembly, including the sleeves

54

,

90

,

60

and

82

, to rotate where the openings

62

,

83

,

56

and

84

are pointed downwardly; so that gravity allows the finished parts of the type shown in

FIG. 2

to drop out of the open slots. Rotation another 180° back to the position shown in

FIGS. 4

,

5

and

7

is effected. Rotation of the mandrels

30

/

28

ceases; and the mandrel support members

24

and

26

are moved back to the positions shown in

FIG. 4

by the control and drive motor mechanism

94

. The finished parts drop free. The system now is ready for a new cycle of operation, repeating all of the steps which have been described above.

The foregoing description of a preferred embodiment of the invention is to be considered as illustrative and not as limiting. Various changes and modifications will occur to those skilled in the art for performing substantially the same function, in substantially the same way, to achieve substantially the same result without departing from the true scope of the invention as defined in the appended claims.

Number	Name	Date	Kind
4422999	Mitchell	Dec 1983	A
5287850	Haber et al.	Feb 1994	A

Process of making a coil in a length of thermoplastic tubing

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Term Extension

Abstract

Description

Claims

US Referenced Citations (2)