NZ232997A

NZ232997A - Blow moulding an outer vessel around but spaced from a preformed inner vessel

Info

Publication number: NZ232997A
Application number: NZ232997A
Authority: NZ
Inventors: George Kosmakos
Original assignee: Insulated Containers Pty Ltd
Priority date: 1989-03-23
Filing date: 1990-03-20
Publication date: 1991-12-23
Also published as: GR900100218A; CA2049968A1; JPH04505592A; WO1990011176A1; EP0509987A4; KR920700885A; EP0509987A1; ZA902267B

Description

<div class="application article clearfix" id="description"> 2 3 2 9 9 7 r Priority Date<s}:. specif3-ration Fifed: ....O..7.^V$0- Class: 2 3 DEC 1991 l 1* '*,iCX, i !-V'' •4/.^3|'^- i NEW ZEALAND PATENTS ACT, 1953 paV-NI Off" iOM^1990 HECEN^O, No.: Date; COMPLETE SPECIFICATION BLOW MOULDING MULTIPLE WALLED ARTICLES spl We, INSULATED CONTAINERS PTY. LTD, a company incorporated under the laws of the State of Victoria, of 14 Hinkler Road, Mordialloc, Victoria 3195, Australia hereby declare the invention for whichsf I we pray that a patent may be granted to _p»e7us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) 2 3 29 la o V 10 15 This invention relates to blow moulding of multiple walled hollow articles and in particular, although not limited to, containers having an external wall of 20 thermoplastics material. In the past, in the construction of double walled thermoplastics containers such as insulated vessels having an internal wall defining a food or beverage ^ 25 retaining cavity and spaced from ..an external wall, often with an insulating medium in the cavity between the walls, a number of manufacturing steps have been required. Generally, the inner and outer walls were moulded as separate articles, the inner wall was inserted 30 into the outer wall, and the margins of the walls were sealed together, often with a capping ring. Preformed insulating segments have been introduced between the walls as the walls are fitted together. The multiple mouldings and fabrication steps required by this 35 technique have been inconvenient insofar as the insertion and capping/sealing steps have been time consuming and accordingly expensive, while requiring the manufacturer o to keep stocks of each of the preformed components required to form the double walled container. It has been proposed in British Patent Specification 5 No. 1,117,140 to blow mould an outer vessel around a preformed inner vessel, thereby reducing the number of fabrication steps and the necessity to keep stocks of each of the components of the container. In this patent, the interior surfaces of a preformed inner vessel are *0 10 supported on a mandrel, a parison is extruded around the inner vessel and the parison is blow moulded to form an outer wall of the finished article. The mandrel has an internal heating/cooling system and serves to prevent destruction or deformation of the inner vessel during 15 blow moulding of the outer wall. The need for a supporting mandrel does not allow this technique to be used with anything other than straight necked inner vessels, as otherwise the mandrel cannot support all of the interior surfaces of the inner vessel. Similarly, 20 the technique cannot be used to mould multiple walled vessels having three or more concentric vessels as access cannot be provided for the supporting mandrels into each of the various inter-wall spaces. 25 British Patent Specification No. 1,125,609 describes a process for manufacturing a fishing float in which a hollow member is inserted between the halves of a mould, a layer of material of greater flexibility than that of the material of the hollow member is positioned between 30 the hollow member and the mould and wherein the mould • halves are closed to vacuum or blow mould the layer about the mould to form a space between the layer and hollow member. The hollow member defines the sealed, internal flotation tank of the float and to prevent its 35 deformation during the blow or vacuum moulding of the , _ ^ exterior, the hollow member must be of appreciable rigidity. ^ \ A O'A -8 hinw 1QQ1" '] - u.r 2a 232937 232m It is an object of the present invention to ameliorate some of the shortcomings evident in prior art techniques for producing hollow multiple walled articles. 5 In accordance with the present invention there is provided a method of blow moulding a multiple walled hollow article in which an inner vessel having a neck and a hollow body is juxtaposed with a mouldable sheet extrusion, 10 the segments of a split mould are closed onto the extrusion to form a substantially sealed parison around the body of the inner vessel in the mould with an annular end portion of the parison extending closely around the Q © -8 NOV 199/ / /':. m 2 3 2 9 neck of the inner vessel and a fluid pressure medium is applied to a space defined between the body of the inner vessel and the sealed parison to form a blow moulded outer vessel, 5 the method being characterized by pressurizing the interior of the inner vessel with a fluid pressure medium during blow moulding of the outer vessel. Further according to the present invention there is ^ 10 provided a hollow multiple walled article blow moulded by the method described in the immediately preceding paragraph. The invention also provides blow moulding apparatus 15 for producing a hollow multiple walled article, the apparatus comprising: means for extruding mouldable sheet material; means for supporting an inner vessel in juxtaposition with the mouldable sheet extrusion, the 20 inner vessel having a neck and a hollow body; split mould segments arranged to close onto the mouldable sheet extrusion to form a substantially sealed parison around the body of the inner vessel in the mould with an annular end portion of the parison extending 25 closely around the neck of the inner vessel; and means for applying fluid pressure to a space defined between the body of the inner vessel and the mould segments to blow mould the parison onto the mould, ^2) "the apparatus being characterized by further 30 comprising means to apply fluid pressure to the interior of the inner vessel during blow moulding of the parison. In the method and apparatus of the invention, the application of the fluid medium to the interior of the 35 inner vessel can prevent the inner vessel from being distorted, burst or otherwise damaged during blow moulding of the outer vessel. The pressure in each of 2329 4 the space between the inner and outer vessels and the interior of the inner vessel is advantageously substantially equal during the blow moulding step. Conveniently the same source of pressure medium is provided for said space and said interior in which case means may be provided in the pressure medium conduit for compensating for differences in volume between said space and said interior in order to apply the desired pressure thereto. The volume compensation means may be in the form of pressure regulating means and/or variable voluice means. In one embodiment of the multiple walled hollow article, the space defined between the inner vessel and outer vessel is used to insulate the inner vessel. This may be achieved by drawing a vacuum in the said space and sealing it upon removal of the respective fluid pressure application means. Alternatively, an insulation medium such as a foamed polyurethane may be injected into the space. In another embodiment of the multiple walled hollow article, the space between the inner vessel and outer vessel is itself used as a separate storage space for beverages etc. or a removable heat exchange medium such as iced water. To achieve this the said space can be provided with its own neck and stopper or cap to allow access therein. The inner vessel may itself define a plurality of interior cavities and unless a contrary sense is implied, the term should hereinafter be construed to include such multiple cavity vessels. In one arrangement of a multiple cavity inner vessel, the hollow body is partitioned by one or more internal walls to define a plurality of side by side ''"fc&pi-J,; 232 cavities. In an alternative arrangement, a multiple cavity inner vessel may comprise a central interior cavity surrounded by a plurality of concentric walls defining at least one substantially annular space around 5 the central cavity. Conveniently, with each of these multiple cavity arrangements, each cavity is provided with a respective neck to allow access therein so as to allow a plurality 10 of different beverages etc. to be carried without intermixing. To achieve this it will generally be necessary for the parison to be confined closely around each of the necks during blow moulding of the outer vessel. Where a multiple cavity inner vessel is provided 15 with a respective neck for each cavity it will generally be necessary to provide a respective source of fluid pressure for each of the necks to ensure pressurization of each cavity is achieved. 20 The annular end portion of the parison which extends around the or each neck of the inner vessel will typically seal therearound by shrinking thereon. If the compositions of the inner and outer vessels are compatible, the closing of the mould segments may cause 25 the portion of the parison lying closely around the neck of the inner vessel to become welded thereto to form a common neck of the hollow multiple walled article. Alternatively, the necks of the inner and outer vessels may be adhesively bonded together. 30 Conveniently, the outer surface of the neck of the inner vessel is provided with protruding beads or ribs around which the parison may extend during sealing thereof around the neck, thereby to more securely anchor 35 the neck of the outer vessel to the neck of the inner vessel. In particular, beads or ribs on the neck extending in a generally axial direction (i.e. from the 2 3 2 9 o lip of the neck towards the bottom of the inner vessel) may, when the neck of the outer vessel is shrunk thereover, prevent the inner vessel from rotating relative to the outer vessel. Grooves provided axially 5 along the neck of the inner vessel may have the same effect. Alternatively ribs or grooves provided circumferentially around the neck of the inner vessel may, when the parison is shrunk and sealed therearound, prevent the inner vessel from being dislodged from the 10 outer vessel in an axial direction. In a still further embodiment, the fluid pressure medium for blow moulding the outer vessel may be introduced around the neck of the inner vessel so that a 15 gap remains between the necks of the inner and outer vessels which may be sealed, for example by an insulating material which assists location of the inner vessel relative to the outer vessel in the finished article. 20 In general, the space defined between the inner vessel and the1 mould segments within which the outer vessel is blown will extend substantially annularly around the inner vessel. Alternatively the outer vessel may extend along a portion of the inner vessel body as 25 well as its neck to form a common multilayered wall and thus the space between the inner and outer vessels will have a somewhat C-shaped cross section. tw<) Protruding ridges or beads, as discussed above in 30 relation to the neck of the inner vessel may also be provided on the body of the inner vessel to assist in locating it within the outer vessel. With this arrangement, the closing of the mould segments will generally cause the parison to lie or become welded 35 adjacent the ridges or beads, and the blow moulding step will produce hollow regions therearound. 0^ n 232 Conveniently, a blow pin for blow moulding the outer vessel enters the mould at an end portion remote from where the end portion of the parison will be moulded around the neck of the inner vessel, in which case a 5 small aperture will typically remain in the bottom of the finished article. Alternatively, the blow pin may enter the split mould to one side of the portion which moulds the outer vessel around the neck of the inner vessel. In each case the remaining aperture may be used to insert an 10 insulating material such as polyurethane foam or to draw a vacuum in the space defined between the inner and outer vessels. The fluid pressure medium will generally comprise 15 air, but other fluids may be appropriate. For instance, it may be appropriate to inject a settable liquid as the blowing medium, which on setting may act as an insulator for the hollow double walled article. 20 The material for the inner vessel may comprise any appropriate material but will generally be a plastics material. Alternatively the inner vessel may comprise other materials such as glass or metal. It will be appreciated that the application of a fluid pressure 25 medium to the or each interior cavity of the inner vessel may allow a comparatively fragile inner vessel to be used. The inner vessel may have a composite construction having, for instance, an insulating layer on external l,lL_y surfaces thereof. Where the inner vessel is itself of 30 multiple cavity construction each of its respective vessels may be of different materials. The mouldable sheet extrusion to form the sealed parison will generally be an open tubular parison. 35 Alternatively the mouldable sheet extrusion may take the form of two or more opposed sheets, edges of which are sealed together by the closing split mould segments to 232 8 form the sealed parison. Materials appropriate for the parison include, for instance, polyethylene, PVC, polycarbonate, polyamide, polyacetal. The inner vessel may be placed under an extrusion port and the mouldable sheet extrusion extruded around or adjacent the inner vessel. Alternatively it may be appropriate to extrude an appropriate length of mouldable sheet extrusion and then to juxtapose the inner vessel within or between portions of the mouldable sheet extrusion. This may be achieved by manoeuvring the inner vessel into place within or between the mouldable sheet extrusion. With either of the above arrangements, extruders which do not constantly extrude the sheet material are particularly convenient to allow sufficient time to complete the juxtaposition, mould closing and opening, blow moulding and exhaust steps, before the next length of sheet material is extruded. An accumulating head extruder, in which the extrudable material accumulates in a piston arrangement when extrusion is interrupted, is an example of a non constant extrusion apparatus. An alternative extruder uses travelling nippers or scissors which cut the top of an appropriate length of extrusion and convey it away from the extrusion port, for instance, down towards a moulding station disposed below the parison extrusion area to be juxtaposed with the inner vessel. A travelling parison arrangement is particularly convenient as it may allow a further length of mouldable sheet extrusion to be prepared while a first length is being sealed with the mould segments and blow moulded. 232 9 Two embodiments of a hollow double walled article made in accordance with the invention will be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side sectional view of a first embodiment of a blow moulding apparatus with mould segments in the open position; Figure 2 is a side sectional view of the first embodiment with the mould segments in the closed position; and Figure 3 is a front sectional view of a second embodiment, looking into a mould segment. In figures 1 and 2, the blow moulding apparatus 10 comprises a parison extruder 12 for extruding a tubular mouldable sheet extrusion. The extruder has a screw feed 14 and annular extrusion port 16 for producing an open thermoplastics parison 18. Extending through the parison extruder 12 and coaxial within the extrusion port 16 is a blow pin 20 connected to an air supply (not shown). The blow pin 20 extends below the parison extruder 12. Parison cutting means (not depicted) are also provided below the parison extruder, adjacent the extrusion port 16. The blow moulding apparatus further comprises a pair of matable blow mould segments 30, 32 adapted to close in a horizontal plane around a portion of the parison. In figure 1 the blow mould segments 30, 32 are depicted in an open position (support means omitted for clarity) and in figure 2 the blow mould segments are depicted in the closed position, clamped around a parison length. The blow mould segments 30, 32 may themselves act as the parison cutting means. Each blow mould segment 30, 32 has an internal moulding surface 34, 36 respectively defining two halves of a screw necked bottle. At the top each blow mould «v.,t WW , 2 3 29 10 segment 30, 32 has an upper half gate 38 to accommodate the blow pin when the mould segments 30, 32 are closed therearound. A lower blow pin 40 extends upward from a point below, but coaxial with, the upper blow pin 20. 5 Each mould segment 30, 32 has a lower half gate 42 at a bottom portion thereof to accommodate the lower blow pin 40 when the mould segments are closed therearound. The lower blow pin 40 is connected to the same air 'i 10 supply as the upper blow pin 20 through a regulator (not shown) able to adjust the air flow through each blow pin relative to each other to apply an appropriate volume of air through each blow pin and thus equalize pressures as described in greater detail below with reference to 15 figure 3. The nozzle 44 of the lower blow pin 40 has an exterior surface 46 adapted to be snugly received in the neck 48 of a preformed inner vessel 50. The inner vessel 20 50 is held, neck down within the open parison and is generally coaxial with it. The surface 46 of the lower blow pin nozzle 40 is positioned such that the lower half gates 42 of the blow mould segments 30, 32 can accommodate the neck 48 of the 25 inner vessel 50. When positioned on the lower blow pin nozzle 40, the end 52 of the inner vessel 50 remote from the neck 48 lies near, but not touching the upper blow pin 20. 30 As shown in figure 1, an annular space 54 is defined between the open parison 18 and the inner vessel 50 when the mould is in the open position. 35 Generally, the lower blow pin 40 will be retractable such that an inner vessel 50 can be inserted thereon and the inner vessel manoeuvred into the appropriate position 232 n coaxial with the parison extrusion port 16. A parison length is then extruded around the inner vessel 50 through the extrusion port 16. Extrusion is ceased when the end 56 of the parison is at least parallel with the neck 48 of the inner vessel. Thereafter, the mould segments 30, 32 are closed around the parison 18 thereby cutting off any excess length of parison. Lower moulding surfaces 58 and 60 adjacent the lower gate halves 42 together defining the screw neck of the finished moulding, force the lower end portion of the parison, adjacent its end 56, closely against the neck 48 of the inner vessel to shrink it therearound and form a common neck for the finished moulding, and so seal the end of the parison remote from the upper blow pin 20. The upper gate halves 38 of the mould segments 30, 32 close around the upper blow pin 20 and so seal that end of the parison. A fluid pressure medium such as air is introduced to the now sealed annular cavity 54 through the upper blow pin 20 to blow mould an outer wall 60 of the finished article, against the moulding surfaces 34, 36 of the mould segments and thus to form a double walled hollow article having the walls united at a common neck but having an annular space between the walls elsewhere. Fluid pressure medium may also be introduced to the annular space 54 prior to sealing of the neck 48. A fluid pressure medium is also introduced into the interior 62 of the inner vessel through the lower blow pin 40 to equalize pressure within the annular space 54 and the interior of the inner vessel 62. As the respective volumes of annular cavity 54 and the interior 52 of the inner vessel are different, to equalize their pressures requires that the respective volumes of air blown in should also be correspondingly different. One TiSW&i,; 1 n n O 2 3 2 9 9/ 12 arrangement of achieving this differential volume of air is described in greater detail with reference to figure 3. 5 After blow moulding has been completed, and the outer vessel has cooled sufficiently, the air is exhausted in such a manner that the respective pressures within the inner vessel and between the inner and outer vessels are maintained substantially equal to each other 10 to prevent distortion or rupture of the inner vessel. The mould segments 30, 32 are then opened, and the lower blow pin, with the double walled article attached may be retracted to remove the article from the upper blow pin 20, leaving an aperture in the outer wall 60 at the end 15 of the vessel remote from the common neck. This aperture may be used, for instance, to insert an insulation medium such as a foaming polyurethane composition. The embodiment of Figure 3 is similar in overall 20 concept but moulds a common neck between the inner and outer walls of the article, adjacent an aperture for inserting a blow pin into the generally annular cavity between the walls. 25 In figure 3, a front view of a split mould segment 70 is depicted with an inner vessel 72 in place on a first blow pin 74. A similar, opposed split mould segment (not shown) defines the mould when closed on the mould segment 70. As with the embodiment of figures 1 30 and 2, the neck 76 of the inner vessel is snugly received on a nozzle 88 of the blow pin 74. Adjacent a gate 78 of the mould for receiving the first blow pin 74, threaded internal surfaces 90 of the mould, in the closed position closely surround the neck 76 to weld the neck to a 35 parison. The mould segment 70 has a further gate 82 for receiving a second blow pin 84 which extends into a cavity 86 between a moulding surface 90 of the mould 4-, .A' - *.V« O 2329 9 7 13 segment 70 and the inner vessel 72. Between the gates 78, 82 the internal surface of each mould segment has a raised handle moulding portion which cooperate to allow a handle to be integrally blow moulded with the outer vessel. The position of the tubular parison, prior to closing the mould segments is indicated by phantom lines 92. The respective volumes of the inner vessel and the ' J 10 space defined between the inner vessel and the moulding surfaces of the mould segments differ. As it is desirable to equalize the pressure in each of these volumes during the blow moulding step and subsequent air exhaust step, the apparatus is provided with pressure 15 equalization means to allow a single source of air to metre a respective appropriate volume of air into each space. The pressure equalization means comprises a source 20 of pressurized filtered air (not depicted) connected to an air line 94. The air line 94 has an adjustable regulator 96 upstream of a solenoid two way valve 98 having an exhaust port 100 and downstream line 102. The downstream line 102 branches into an inner vessel line 25 104 leading to first blow pin 74 and an outer vessel line 106 leading to the second blow pin 84. Inner vessel line 104 and outer vessel line 106 each have a respective flow control valve 108, 110 intermediate its blow pin and its connection to the air line 94. The flow control valves, 30 two way valve and regulator are shown schematically in this drawing. The flow control valves 108, 110 each serve to independently regulate air flow in both the blowing and exhaust directions. 35 To further metre the respective volumes of air to be applied from each blow pin 74 and 84, the inner 104 and outer 106 air lines each have a respective variable 232 14 volume chamber 112, 114 in the form of an adjustable piston arrangement. Thus, the difference in volume between the interior volume of the inner vessel 72 and the space between the inner vessel and moulding surfaces 86 can be compensated by appropriate adjustment of each variable volume chamber thereby to allow an equalization of pressure within each of these spaces during blow moulding and subsequent exhaust. In figure 3, the volume of the variable volume chamber 112 associated with the inner vessel blow pin 74 is relatively small as its piston 116 is near the end of its stroke and is disposed adjacent the variable volume chamber's connection 118 with air line 104. In contrast, variable volume chamber 114, to metre a smaller volume of air to be blown into the relatively small space 86 defined between the inner vessel and moulding surfaces, has its piston 120 set to define a relatively large volume. The respective adjustments to suit a particular common air input pressure can be set empirically or by mathematical calculation of the differences in volume of air to be blown. This arrangement of pressure equalization means is particularly convenient as it allows air pressure within the inner vessel and outer vessel to be equalized yet uses a single source of air pressure. Furthermore, because the variable volume chambers 112, 114 and flow control valves 108, 110 are each independently adjustable, the apparatus can be adapted to blow mould hollow multiple walled articles of different volumes and configurations. Adjustment of the volumes of fluid pressure medium metred through each blow pin has been discussed by reference to equalization of the pressure achieved in the inner vessel and between the inner vessel and parison. It will be apparent, however, that particularly where the robustness of the inner vessel is known, some variance in 232997 15 the pressures required in each space may be allowed and the variable volume geometry herein described can be used accordingly. 5 Typically, moulding of double walled articles according to the second embodiment may involve placing a preformed inner vessel 72 upon the first blow pin 74 and adjacent the second blow pin 84, whereupon a parison length extruded elsewhere and supported by cutting 'w' 10 scissors may be manoeuvred over and descend around the inner vessel 72. Mould segments 70 are then closed around the parison whereupon a common neck of the double walled article is formed around the first blow pin. Air is applied to the cavity 86 between the inner vessel 72 15 and moulding surfaces 90 of the mould to blow mould a double walled hollow article having an integral handle, a common neck and a cavity between the walls. An insulating material, such as a foaming 20 polyurethane composition may be introduced to the cavity between the walls of the double walled article by way of the aperture left in the outer wall after withdrawal of the blow pin 84. O 25 Alternatively, where this double walled article is itself used as the inner vessel for a further application of the method and apparatus of the present invention, the aperture left in the outer wall after the withdrawal of the blow pipe 84 may be used to apply fluid pressure 30 medium in addition to fluid pressure medium applied to the innermost vessel 72 through its neck 76, during the blow moulding of an outermost vessel. With this further application to mould a multiple wall article, it may be particularly convenient to provide the blow pin for blow 35 moulding the outermost vessel at the remote end relative to the neck of the innermost and intermediate vessels. 23299 7 16 The described embodiments have been advanced merely by way of explanation and many modifications may be made thereto without departing from the spirit and scope of the invention which includes every novel feature and combination of novel features herein disclosed. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 2329 9 7 17 WHAT WE CLAIM IS:

1. A method of blow moulding a multiple walled hollow article, in which an inner vessel having a neck and a hollow body is juxtaposed with a mouldable sheet extrusion, the segments of a split mould are closed onto the extrusion to form a substantially sealed parison around the body of the inner vessel in the mould with an annular end portion of the parison extending closely around the neck of the inner vessel and a fluid pressure medium is applied to a space defined between the body of the inner vessel and the parison to form a blow moulded outer vessel, the method being characterized by pressurizing the interior of the inner vessel with a fluid pressure medium during blow moulding of the outer vessel.

2. A method according to claim 1 in which the respective pressures in the space defined between the body of the inner vessel and the parison and in the interior of the inner vessel are maintained substantially equal during blow moulding.

3. A method according to claim 1 in which a single source of fluid pressure medium is used and wherein differences in volume between the interior of the inner vessel and the said space are compensated for.

4. A method according to claim 3 in which to achieve said compensation, a different volume is provided in each of the fluid pressure medium flowpaths intermediate the single source of fluid pressure medium and the respective interior of the inner vessel or the space defined between the inner vessel and the parison.

5. A method according to claim 4 in which the said 18 different volumes are achieved by a variable volume means associated with at least one of said flowpaths.

6. A method according to claim 1 in which an insulation medium is injected into the space defined between the body of the inner vessel and the blow moulded outer vessel.

7. A method according to claim 6 in which the insulation medium forms at least a part cf the fluid pressure medium used to blow mould the outer container.

8. A method according to claim 1 in which closing of the split mould segments causes the annular end portion of the outer vessel to weld to the neck of the inner vessel.

9. A method according to claim 1 in which the inner vessel defines a plurality of interior cavities, each with a respective neck and wherein each cavity is pressurized with fluid pressure medium during blow moulding of the outer vessel.

10. A method according to claim 1 in which the space defined between the body of the inner vessel and the parison extends annularly around the said body.

11. A hollow multiple walled article produced by the method of claim 1.

12. Apparatus for producing a hollow multiple walled article, the apparatus comprising: means for extruding mouldable sheet material; means for supporting an inner vessel in juxtaposition with the mouldable sheet extrusion, the inner vessel having a neck and a hollow body; split mould segments arranged to close onto the 232 19 mouldable sheet extrusion to form a substantially sealed parison around the body of the inner vessel in the mould with an annular end portion of the parison extending closely around the neck of the inner vessel; and means for applying fluid pressure to a space defined between the body of the inner vessel and the mould segments to blow mould the parison onto the mould, the apparatus being characterized by further comprising means to apply fluid pressure to the interior of the inner vessel during blow moulding of the parison.

13. Apparatus according to claim 12 in which the means for supporting the inner vessel is a blow pin extending through the inner vessel neck.

14. Apparatus according to claim 12 in which a single source of fluid pressure medium supplies each fluid pressure application means, the apparatus further comprising means to compensate for differences in volume between the Interior of the inner vessel and the space defined between the inner vessel and mould segments thereby to maintain a respective desired pressure in each of the said interior and said space.

15. Apparatus according to claim 14 in which the volume of the respective fluid pressure medium flowpaths intermediate the single source of fluid pressure medium and the interior cavity of the inner vessel or the said space between the body of the inner vessel and mould segments are different.

16. Apparatus according to claim 15 in which at least one of said flowpaths comprises variable volume means.

17. Apparatus according to claim 12 adapted for inner vessels defining a plurality of interior cavities, the apparatus comprising means to apply fluid pressure to 2329 20 each of said cavities.

18. Apparatus according to claim 12 further comprising travelling scissors or nippers to transport the mouldable sheet extrusion away from an extrusion outlet of the extrusion means for juxtaposition with the inner vessel.

19. Apparatus according to claim 12 in which the extrusion means comprises an annular extrusion outlet disposed concentrically above the means to support the inner vessel.

20. Apparatus according to claim 12 in which the means to apply fluid pressure to the space defined between the body of the inner vessel and the mould segments extends or opens into the mould adjacent the support for the inner vessel.

21. Apparatus according to claim 12 in which the means to apply fluid pressure to the space defined between the body of the inner vessel and the mould segments extends or opens into the mould remote from the support for the inner vessel.

22. Apparatus according to claim 12 comprising means to inject an insulation medium into the space defined between the body of the inner vessel and the mould segments.

23. Apparatus according to claim 22 in which the insulation medium injection means is in communication with a fluid pressure medium flowpath of the means to apply fluid pressure to the space defined between the body of the inner vessel and the mould segments.

24. A method of blow moulding a multiple walled hollow article substantially as hereinbefore described with reference to the accompanying drawings. 23299 7 21

25. Apparatus for producing a hollow multiple walled article substantially as hereinbefore described with reference to the accompanying drawings. B their authorised Agents A .J. PARK & SON. </div>