GB2218666A

GB2218666A - Sheet forming

Info

Publication number: GB2218666A
Application number: GB8911494A
Authority: GB
Inventors: Ernest Albert Thorne
Original assignee: Medicor Internaltional Ltd
Current assignee: Medicor Internaltional Ltd
Priority date: 1988-05-19
Filing date: 1989-05-18
Publication date: 1989-11-22
Also published as: GB8811864D0; GB8911494D0; WO1989011388A1; AU3697389A

Abstract

Contraceptive sheath manufacture and associated method, wherein a preform (1) of, say, polyurethane, has an outer ring (2) and a membrane (3) which is deformable into an intermediate shape and wherein a pressure differential is applied between the interior and exterior of the intermediate shape to cause further deformation thereof into a final, desired shape of seamless sheath body defined by an associated mould (111). The pressure differential is preferably in the form of a vacuum generated within the mould (111) and the initial deformation of the membrane (3) is carried out by a mandrel of desired shape. The preform (1) is also preferably pre-heated prior to the initial deformation step.

Description

CONTRACEPTIVE SHEATH PREFORM AND MANUFACTURE DESCRIPTION This invention relates to the manufacture of contraceptive sheaths and especially, but not exclusively, to the manufacture of female contraceptive shields, such as, those sold under the Registered Trade Mark "FEMSHIELD", as well as to a preform for use in such manufacture.

In accordance with one aspect of the present invention, there is provided a preform for use in the manufacture of a contraceptive sheath, which preform comprises a membrane of a suitable material which is secured to and extends across the area defined within an outer ring and which is capable of being shaped into a seamless body of the sheath.

In accordance with another aspect of the invention, there is provided further a method of manufacturing a contraceptive sheath, wherein a sheet of suitably deformable material is deformed into an intermediate shape and a pressure differential is applied between the interior and exterior of the intermediate shape to cause further deformation thereof into a final shape of seamless sheath body defined by an associated mould.

Pre#ferably, the sheet of suitable material, such as, a synthetic plastics material, is deformable by, say, heating and stretching or by thermo-forming into a seamless sheath body of the intermediate and final, desired shapes.

A ring, which may be located around the open end of the finished sheath with the desired shape of body and which may be of any suitable material, such as, that from which the sheet or membrane is made, may be attached to the sheet, for instance, by welding or heat sealing prior to or during the shaping operation.

Alternatively, the ring may be attached to the seamless sheath body after such shaping/deforming operation.

In accordance with a further aspect of the invention, there is also provided apparatus for manufacturing a contraceptive sheath, comprising means arranged to deform a sheet of suitable material into an intermediate shape and means arranged to apply a pressure differential between the interior and exterior of the intermediate shape, thereby causing further deformmation thereof into a final shape of seamless sheath body defined by an associated mould.

In the inventive method and apparatus, asdefined above, the sheet of suitable material is preferably constituted by the membrane of the inventive preform also defined above, in which case, the membrane may also be of a synthetic plastics material and may be deformable by, say, heating and stretching or thermoforming into the intermediate and final seamless sheath body shapes The ring which is located around the open end of the final shape of sheath body and which may be of any suitable material, such as, that from which the membrane is formed, may be attached thereto, for instance, by welding, ultrasonic or otherwise, or by heat sealing.

Also, the membrane of the so-called preform is preferably circular with the ring attached to the circumference thereof, such attachment being effected by any suitable method, for instnace, by welding or heat sealing, as described above. Alternatively, the preform may be made as an unitary item by, for instance, moulding, preferably, injection moulding.

Again, the membrane is preferably stretchable or otherwise deformable into the shape of the seamless sheath body and is, along with any associated ring, made of a synthetic plastics material and, more preferably, an elastomer, such as, polyurethane, which can be heated prior to the stretching or other deformation operation, to facilitate such operation Advantageously, the thickness of the membrane or other form of suitable sheet material is such that, when it is strc-tched into the required shape of seamless sheath body, the latter possesses the necessary strength and elasticity to perform its proper function.In a preferred embodiment, the thickness of the circular membrane of a preform made from Dolyurethane, is from about 120 f (0.005 inches) to 500 f (0.020 inches), and preferably 240 P (0.010 inches), such that the thickness of the wall of the sheath body is about 40 f (0.0015 inches).

The temperature to which the preform may be heated prior to and/or during the shaping operation is dependent upon a number of operating parameters, such as, the actual thickness of the membrane, the material from which the membrane is made and other physical characteristics of the membrane material and associated tooling.

In a preferred embodiment of the inventive method and apparatus for carrying out such method, a tool is employed, which comprises a female mould which has the same internal shape and size as those of the desired sheath body and into which is insertable at least partially a male mandrel whose shape corresponds to that of the intermediate, with the preform being locatable over the open end of the female mould, such that, when the male mandrel is inserted therein, the membrane, preferably pre-heated, is deformed by stretching into the intermediate shape and then, upon application of the pressure differential between the interior and exterior of the intermediate sheath body shape, is deformed further into the internal shape of the female mould.

At least one part of the tool may be heatable, as may be the preform. Also, the pressure differential is advantageously in the form of a vacuum applied to the exterior of the intermediate sheath body shape via a suitable arrangement provided in the associated female mould.

In order that the invention may be more fully understood, preferred embodiments in accordance therewith will now be described by way of example and with reference to the accompanying drawings in which: Fig. 1 is a plan view of a preform from which a female contraceptive shield can be manufactured; Fig. 1A is a section along the line A-A in Fig. 1; Fig. 2 is a forme for use in manufacturing the preform shown in Figs. 1 and lA; Fig. 3 is a diagrammatic elevation of apparatus for manufacturing a female contraceptive shield from the preform shown in Figs. 1 and lA; Fig. 4 is another diagrammatic elevation, in more detail and on a larger scale, of the apparatus shown in Fig. 3; Fig. 5 is a diagrammatic elevation of a preform loading station of the apparatus shown in Figs. 3 and 4; ; Fig. 6 is a diagrammatic elevation of a temperature monitoring device of the apparatus shown in Figs. 3 and 4; Fig. 7 is a diagrammatic elevation of a side view of a portion of the apparatus shown in Figs. 3 and 4; Fig. 8 is a side elevation, again diagrammatic, of a supplementary ring feeder station of the apparatus shown in Figs. 3 and 4; Fig. 9 is a diagrammatic elevation of a leak testing station of the apparatus; Fig. 10 is a diagrammatic plan view of the apparatus; and Figs. 11A and liB are respective partial plan and elevational views of a modified form of the apparatus.

Referring firstly to- Figs. 1, 1A and 2 of the drawings, a preform indicated generally at 1, comprises a polyurethane ring 2 and a polyurethane membrane 3 which is attached to the ring and which extends over the area defined within the ring.

The preform 1 is manufactured using a forme, a shown at 10 in Fig. 2, comprising a rectangular base 11 with a plurality of circular grooves 12 provided thereon by concentric pairs of upstanding elements 13,14 of which the outer one 14 has an upper cutting edge.

In this particular embodiment, the forme 10 has sixty such grooves 12, although only five are shown in Fig. 2.

Each groove 12 is arranged to receive a preformed polyurethane ring 2 therein and the forme 10 constitutes one half of a die, the other half (not shown) being constituted by a heatable flat plate which can be brought into confronting relationship with the forme 10, with a piece of polyurethane sheet (also not shown) located therebetween. In this manner, the heated working surface of the flat plate of the other half of the die is brought into engagement with at least the cutting edges of the elements 14 upstanding from the forme 10, thereby heat sealing each ring 2, previously received in a respective groove 12, to the polyurethane sheet, whilst simultaneously severing the excess sheet from around the so-formed preforms 1.

An alternative method of manufacturing the preforms 1 is to use a moulding technique, such as, injection moulding, thereby forming initially an integral or unitary item in the form of a moulded preform.

The preforms may now be used in conjunction with apparatus for manufacturing female contraceptive shields, as will now be described with reference to Figs. 3 to 11 of the accompanying drawings.

Thus, apparatus for manufacturing female contraceptive shields, as indicated generally at 101 in Figs.

3, 4 and 10, comprises a rigid base 102 upon which is mounted chain-driven indexing means (not shown) for moving sets, in this case, eight, of supports 103 to respective operating stations A' to D' and A'' to D''.

Each set of supports 103 contains five supports and each of two sets of operating stations consists of a preform loading station A',A'', a shaping station B',B'', a supplementary ring feeding station C',C'' and a leak testing/ejection station D',D''.

At each preform loading station A' ,A'', a preform 1 is loaded on to each of five supports 103, so that the ring 2 of each preform is located and retained in a complementary, circular groove 103' in the support.

Such loading is effected by means of an arrangement as shown in Fig. 5 wherein the preforms are stacked in a magazine 52 and a loading head 51 is arranged to engage the membrane 3 of the lowermost preform of each stack thereof. A vacuum applied to that head 51, via suitable vacuum ports (not shown), causes the lowermost preform 1 to become attached temporarily to the head which is then moved downwardly through a central hole 103'' in the support 103. The vacuum is then terminated and the preform 1 is released from the vacuum loading head 51 and located upon the support 103 with its ring 2 received in the circular groove 103'.

This preform loading operation at stations A' and A'' can be performed in any other suitable manner, for instance, by hydraulic and/or pneumatic transfer means or from a loose filled hopper arrangement.

The indexing means then moves the two sets of five preform-loaded supports 103 from the loading stations A',A'' to the next, shaping stations B',B'' in the direction of the arrow X in Fig. 10. At this station B',B'', the preforms 1 are retained in position with respect to their associated supports 103 by means of an elongate clamp 107 which is moved into position by any suitable arrangement. In this position, the preforms 1 are located above the open ends of shaped bores 104 of female moulds 111 in a lowered position and below respective male mandrels 105 in a raised position, as shown in Figs. 3 and 4, although in Fig. 4 the female moulds 11 are shown in a raised position.

Then, a heater 108 is moved, upon slider bars 109, to above the clamp 108 and associated supports 103 and preforms 1, such that the preforms are preheated to the required temperature for sufficient softening thereof and subsequent deformation, at which time the heater 108 is returned to its original, withdrawn position.

The inner profile of each female mould bore 104 corresponds to the final, desired shape of sheild body to be formed by the deformation operation.

It is to be appreciated at this stage that other heating means may be employed, for instance, a ceramic-type heater arrangement which is accurate to 10 Celsius and which eliminates the temperature sensing device shown in Fig. 6 and used in this particular embodiment of inventive apparatus, for controlling the heater 108.

The device in Fig. 6 employs an infra-red detector 61 which is movable into an operating position, as shown in full lines in the Figure, to below the tail end preform 1 from a rest position, as shown in chaindotted lines. A conventional "push-pull" mechanism, as indicated generally at 62, is provided for this purpose.

Beneath the detector 61, in the operative position thereof, is shown, again in chain dotted lines, the associated mould 111 in its lowered position.

With the heater 108 and detector 61 in their respective inoperative positions, the male mandrels 105 are lowered at the same time as the female moulds 11 are raised, such that the mandrels are moved into the moulds through respective apertures 107' in the clamp 107 and through respective central apertures 103'' in the supports 103, whereby the membranes 3 of the associated preforms 1 are deformed into an intermediate shape which corresponds with the shape of the mandrel 105. Each mandrel 105 is very slightly tapered and its end is extended slightly to provide a nipple-shaped protuberance which is a contributory factor to the eventual shape and wall thickness of the shield, although other parameters do have a bearing upon those particular features of the final shape of the shield body.

Also, it is to be noted that the extent to which the mandrels 105 are inserted into their associated moulds 111 is dependent upon the features required in the final product. However, the axial extent of such insertion is generally between one half and one third of the length of the bore 104 of a mould 111.

At the same time as the intermediate shapes of seamless shield body are formed, a vacuum is applied to the exterior of the intermediates in their moulds 111 via vacuum ports 41,42, as shown in Fig. 4.

This vacuum, which generates a pressure differen tial between the interior and exterior of each intermediate shape formed upon the associated mandrel 105, is sufficient to cause further deformation of the intermediate shape to an extent whereby the previously deformed polyurethane material takes up the shape of the mould, it being removed in the process from the mandrels 105.

This final shape is that of the desired seamless shield body.

Although the bringing together of the mandrels 105 and the associated moulds 111 is substantially simultaneous, this need not necessarily be so, depending upon the actual operating parameters. Similarly, the vacuum need not necessarily be applied to the intermediates at the same time as they are formed upon the mandrels, this again depending upon the operating parameters.

A cooling period for the finally formed shield bodies then ensues for a given time with the mandrels 105 raised into their rest positions. Then, the clamp 108 is returned to its inoperative position and the female moulds 111 are lowered to their rest positions.

Reciprocal movement of the heater, prior to the forming operation described immediately above is shown in Fig. 7, with the movement of the heater 108 between its inoperative (full lines) and operative (dashed lines) being indicated by the arrow Y. Similarly, reciprocal raising and lowering movement of each mandrel 105 is shown in Fig. 5, as indicated by the arrow W.

Next, the indexing means moves the respective sets of supports 103 from the shaping stations B',B'' to the supplementary ring insertion stations C' ,C'' where a supplementary ring 2' is inserted into each previously formed shield -500. The supplementary rings 2' improve the application and use of the shields 500 and are fed from a magazine indicated generally at 81 to a dispensing device 82. The lowermost ring 2' is received upon a finger 83 which is shown in its extended position in Fig. 8. When it is retracted, however, the lowermost supplementary ring 2' drops into the open upper end of the shield 500 still located upon its associated support 103. The next, lowermost ring 2' is then fed on to the finger 83 which is now in its extended position once again.

The diameter of the supplementary rings 2' is less than that of the ring 2 at the open end of each shield 500.

Now, the indexing means moves each set of supports 103 and associated shields 500 and inserted supplementary rings 2' to the next, leak testing station D',D'' where a leak testing device for each shield is provided, such as that shown in Fig. 9.

A probe 91 is insertable into each shield 500 in sealing engagement with the support 103 and/or ring 2, to apply a fairly low pressure of air to the interior of the shield, via ports 92,93 connected to an air supply and a balancing reservoir (not shown).

If the shield 500 has been formed properly and contains no leakage holes, then the air pressure between the reservoir and the interior of the shield is in balance.

However, if the shield 500 is leaky in any way, then air will flow from the reservoir into the interior of the shield. Such air flow is used to cool a heated platinum wire which, as a consequence, is cooled, thereby registering a leak in the shield through suitable electronic monitoring instrumentation.

Such instrumentation (not shown) then causes either a leaky shield to be rejected or a secure shield to be ejected for subsequent packaging and transportation.

In this particular embodiment of inventive apparatus, if one leaky shield in a set of five is detected then all five shields are rejected, although these are retrieved for re-testing.

Subsequently, the sets of supports are moved to the next station, namely, the preform loading stations A',A'', by the indexing means, to commence the manufacturing sequence once again.

With reference now to Figs. 11A and 11B of the drawings, here there is shown a modified form of apparatus in accordance with the invention, wherein the apparatus and associated operating stations are in the form of a carousel arrangement with a circular rotatable table 123 with respective operating stations arranged around the periphery thereof, these being a preform loading station A''', a preform heating station B''', a mandrel/mould shaping station C''', a supplementary ring loading station D' ' and a leak testing station E'. The respective components are mounted upon a rigid table 124 with which is associated a stepping motor with a five-stop drive for indexing respective sets of supports associated with the rotatable table 123, the supports performing the same function as the supports 103 of the embodiment described above.

At station C''', there is shown the male forming mandrels 125, a clamp 126 and the female moulds 127.

This embodiment is more compact than the first embodiment described above and, as such, is more easily transportable and operable.

It is to be appreciated that the inventive preform, method and apparatus provide a female contraceptive shield with abody which is eamless and, thus, free of weak areas normally associable with seamed and dipped shield or sheath bodies but that male contraceptive sheaths may also be made in the same way.

Further, it is to be understood that the invention may include modifications not described above but which fall within the scope of the appended claims.

Claims

1. A preform for use in the manufacture of. a contraceptive sheath, which preform comprises a membrane of a suitable material which is attached to and extends across the area defined within an outer ring and which is capable of being shaped into a seamless body of the sheath.

2. A preform according to claim 1 made of polyurethane.

3. A preform according to claim 1 or 2 made by injection moulding.

4. A method of manufacturing a contraceptive sheath, wherein a sheet of suitable material is deformed into an intermediate shape and a pressure differential is applied between the interior and exterior of the inetrmediate shape to cause further deformation thereof into a final shape of seamless sheath body defined by an associated mould.

5. A method according to claim 4, wherein the sheet of suitable material is deformed into the intermediate shape using a mandrel whose profile corresponds to that of the intermediate shape.

6. A method according to claim 4 or 5, wherein the pressure differential is in the form of a vacuum applied to the exterior of the intermediate shape within the associated mould.

7. A method according to claim 4, 5 or 6, wherein the sheet of suitable material is heated prior to its being deformed into the intermediate shape.

8. A method according to any of claims 4 to 7, wherein the sheet of suitable material is constituted by the membrane of a preform according to claim 1, 2 or 3.

9. A method according to any of claims 4 to 7, wherein the sheet is made of polyurethane.

10. A method according to any of claims 4 to 9, wherein a supplementary ring is inserted loosely in the final shape of seamless sheath body.

11. A method according to claim 10, wherein the supplementary ring is made of polyurethane.

lz. Apparatus for manufacturing a contraceptive sheath, comprising means arranged to deform a sheet of suitable material into an intermediate shape and means arranged to apply a pressure differential between the interior and exterior of the intermediate shape, thereby causing further deformation thereof into a final shape of seamless sheath body defined by an associated mould of the apparatus.

13. Apparatus according to claim 12, wherein said sheet deformation means comprises a mandrel whose profile corresponds with that of the intermediate shape.

14. Apparatus according to claim 12 or 13, wherein said pressure differential application means comprises vacuum generating means associated with the mould.

15. Apparatus according to claim 12, 13 or 14, wherein said sheet deformation means is insertable at least partially into the associated mould.

16. Apparatus according to any of claims 12. to 15 including means arranged to heat the sheet of. suitable material prior to the initial deformation thereof.

17. Apparatus according to any of claims 12 to 16 including means arranged to feed said sheet deformation means a preform according to claim 1, 2 or 3, with the membrane of the preform constituting the sheet of suitable material.

18. Apparatus according to any of claims 12 to 17 including means arranged to insert loosely a supplementary ring into the final sheath body.

19. Apparatus according to claim i8, wherein the supplementary ring is made of polyurethane.

20. Apparatus according to any of claims 12 to 18 including means for leak testing the final sheath body.

21. A method of manufacturing a female contraceptive shield substantially and hereinbefore described.

22. Apparatus for manufacturing a female contraceptive shield substantially as hereinbefore described with reference to the accompanying drawings.

23. A preform for use in the manufacture of a contraceptive sheath, substantially as hereinbefore described with reference to the accompanying drawings.