JPH04505592A - Blow molding of multi-walled articles - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Blow molding of multi-walled articles The present invention relates to the blow molding of multi-walled hollow articles, particularly but not limited to thermoplastic The invention relates to the blow molding of containers having an external wall of a plastic material.

In the past, an interior wall that defined a cavity for holding food or drink and was spaced from the exterior wall. double, such as an insulated container, with an insulating medium in the cavity between the walls, often with an insulating medium in the cavity between the walls The construction of wall-mounted thermoplastic containers requires numerous manufacturing steps. there was. Generally, the inner and outer walls are molded as separate articles, with the inner wall inside the outer wall. The periphery of the wall was often sealed together with a capping ring. wall or one When fitted together, preformed insulation segments were introduced between the walls. . The multiple molding and secondary processing required with this technology are It is also expensive for manufacturers to create double-walled containers. The need to keep stock of each of the preformed parts needed for molding It was inconvenient to the extent that it existed.

The outer container is blow molded around the preformed inner container, thereby forming a large number of secondary Reduces the number of processing steps and the need to store separate stocks of container parts It is proposed in British Patent Specification No. 1,125,609. In this patent , the inner surface of the preformed inner container is supported on the mandrel and the parison is the outer wall of a completed article extruded and blown into a parison around a square container; form. The mandrel has an internal heating/cooling system that allows the inner wall to be heated during blow molding of the outer wall. It acts to prevent destruction or deformation of the container. The mandrel is attached to the inner surface of the inner container. Since it is not possible to support all Use with anything other than an inner container with a suitable neck is not permitted. Similarly, the technique The technique is such that access to each of the various interwall spaces is provided to the support mandrel. Since it is not possible to form multi-walled containers with three or more concentric containers, cannot be used for

The present invention aims to improve some of the drawbacks evident in the prior art for producing hollow multi-walled articles. It is an object of the present invention to.

According to the invention, an inner container having a neck and a hollow body can be formed by extruding a sheet. 1. A method of blow molding a multi-walled hollow article juxtaposed with an object, the method comprising: The segments of the split mold are closed onto the extrudate and the sealed parison is placed in the mold. formed around the body of the inner container such that the annular end portion of the parison extends around the neck of the inner container. extending closely to the a space in which a fluid pressure medium is defined between the body of the inner vessel and the sealed parison; In a method of forming a blow-molded outer container, The interior of the inner container is pressurized with a fluid pressure medium during blow molding of the outer container. A method is provided.

Further in accordance with the invention, a hollow hollow body blow molded by the method described in the section immediately above is provided. A multi-walled article is provided.

The present invention also provides a blow molding apparatus for producing a hollow multi-walled article, comprising: An apparatus for extruding formable sheet material and an inner container as well as a formable sheet extrudate. an apparatus supported in positional relation, an inner container having a neck and a hollow body; Place the sealed parison inward in the mold and place it close onto the extrudate. The annular end portion of the parison forms around the body of the container and the inner neck of the container. The closely extending split mold segments and the fluid pressure between the body of the inner container and the mold segments and a device for blow-molding the parison onto the mold by applying a voltage to the space defined between the mold and the mold. In the device that The method further includes a device for applying fluid pressure to the interior of the inner container during blow molding of the parison. Provided is a device characterized by:

In the method and apparatus of the present invention, application of fluid pressure to the interior of the inner container comprises: To prevent the outer container from becoming distorted, bursting or otherwise damaged during blow molding. can be done. The space between the inner and outer containers and the interior of the inner container, respectively. It is assumed that the pressure is approximately equal during the blow molding step. Conveniently, the pressure medium the same source is provided for said space and said interior, in which case the desired pressure is applied thereto. A device for compensating the volume difference between said space and said interior for applying a pressure medium is provided. It can be provided in a tube. Volume compensators are pressure regulators and/or variable volume It can be in the form of a stacking device.

In one embodiment of the multi-walled hollow article, a container defined between the inner container and the outer container The space is used to insulate the inner container. This draws a vacuum into the space. and sealing the space upon removal of each fluid pressure application device. This can be achieved by

Alternatively, an insulating medium such as polyurethane foam can be injected into the space. Ru.

In another embodiment of the multi-walled hollow article, the space between the inner container and the outer container is itself Separate body for drinks etc. or for removable heat exchange media like ice water Used as storage space. To achieve this, the space must be accessible to It can be provided with its own neck and stopper or cap to allow for.

The inner container itself may define multiple internal cavities and may have implications to the contrary. Unless otherwise specified, the term shall be construed below to include such multi-cavity containers. be.

In one configuration of the multi-cavity inner container, the hollow body is configured to define a plurality of side-by-side cavities. separated by one or more internal walls. In an alternative configuration, a multi-cavity inner vessel is a plurality of concentric spaces defining at least one generally annular space around a central cavity. It can include a central internal cavity surrounded by walls.

Conveniently, each of these multi-void configurations allows each cavity to have multiple different that which allows access into it to allow drinks, etc. to be carried without intermixing; Each neck is provided. To achieve this, the parison is used to inflate the outer container. It is generally necessary to be closely confined around each of the necks during molding. Ru. If the multi-void inner container has a separate neck for each cavity, each cavity each for each of the necks to ensure that pressurization in place is achieved. It is generally necessary to provide a source of fluid pressure.

an annular end portion of the parison extending around the neck or respective neck of the inner container; typically seals around it by shrinking over it. If inward and outward If the composition of the container fosters compatibility, the closure of the mold segment is a hollow multi-walled The paris is inwardly extruded closely around the neck to form a common neck of the product. You can weld the son part to it. Alternatively, the inner and outer container nets The blocks can be adhesively bonded together.

Conveniently, the outer surface of the neck of the inner container is provided with projecting beads or ribs; It can extend into the parison around it or its seal around the neck; This locks the neck of the outer container more firmly to the neck of the inner container. In particular, in general A screw on the neck that extends in the direction of the neck axis (i.e. from the lip of the neck towards the bottom of the inner container) The cords or ribs are attached to the inner or outer container when the neck of the outer container is retracted onto it. It is possible to prevent it from rotating relative to the container. axis along the neck of the inner vessel Directional grooves can have the same effect. Alternatively, the inner container net The ribs or grooves circumferentially around the Also prevents the inner container from being moved in the axial direction from the outer container when sealed. can do.

In yet another embodiment, the fluid pressure medium for blow molding the outer container is the fluid pressure medium for blow molding the outer container. between the inner and outer neck of the container so that it can be introduced around the neck A gap remains, which is e.g. the positioning of the inner container relative to the outer container in the finished article. It can be sealed by an insulating material that helps protect the body.

Generally, a space defined between a mold segment and an inner container into which the outer container is blown. extends generally annularly around the inner container. Alternatively, the outer container may have a common multilayer wall. extending along a portion of the inner container body as well as its neck so as to form a portion of the inner container body; , so that the space between the inner and outer containers develops a somewhat C-shaped cross section.

A protruding ridge or bead as described above with respect to the neck of the inner container It can also be provided on the body to aid in its positioning within the outer container. This configuration The closure of the mold segments generally involves placing the parison adjacent to a ridge or bead. Place or weld and a blow molding step creates a hollow area around it.

Conveniently, the blow bottle for blow molding the outer container has an inner end portion of the parison. into the chamber at the end distal from where it is molded around the neck of the container; A mold hole then typically remains in the bottom of the finished article.

Alternatively, the blow bottle is one of the parts that molds the outer container around the neck of the inner container. You can put a split mold on the side. In each case, the remaining holes are filled with polyurethane. or to insert an insulating material such as foam into the inner and outer container. can be used to draw a vacuum into a closed space.

The fluid pressure medium generally consists of air, although other fluids may be suitable. example For example, it may be appropriate to inject a curable liquid as the blowing medium; This can act as an insulator for the hollow double-walled article upon curing.

The material of the inner container can be made of any suitable material, but is generally a plastic material. It is. Alternatively, the inner container may be made of other materials such as glass or metal. can.

The application of a fluid pressure medium to the internal cavity of the inner container or to the respective internal cavity is relatively fragile. It will be appreciated that it may be permissible to use a smaller inner container. The inner container is For example, there can be a composite structure with an insulating layer on its outer surface. inner content If the container itself has a multi-cavity structure, each of its containers is different. It can be of material.

Sheet extrudates that can be formed to make sealed parisons are generally open tubular It is a parison. Alternatively, the formable sheet extrudate can be made of two or more opposing sheets. It can take the form of a slit, the edges of which can be split closed to create a sealed parison. Generally sealed by molded segments.

Suitable materials for the parison are e.g. polyethylene, polyvinyl chloride, polycarbonate. Contains polyester, polyamide, and polyacetal.

The inner container can be placed below the extrusion opening, and the formable sheet extrudate is placed inside the It can be extruded around or adjacent to the container. Alternatively, a suitable length extrude the moldable sheet extrusion of the inner container, then mold the inner container from the moldable sheet extrusion It may be appropriate to juxtapose within or between parts of This is the inner container Achieved by manipulation into place within or between formable sheet extrusions can be done.

In any of the above configurations, an extruder that does not continuously extrude sheet material can produce sheets of length Completes the juxtaposition, mold closure and opening, blow molding and evacuation steps before the material is extruded It is especially useful to allow enough time to do so. Extrude when extrusion is interrupted The accumulating head extruder, in which possible material accumulates in the parison structure, is equipped with a device that does not continuously extrude. An example of this would be to cut off the top of an appropriate length of extrudate and transport it from the extrusion opening, e.g. a forming station located below the parison extrusion area to be juxtaposed with the container; Use moving nippers or scissors to move it down towards the surface. The moving parison structure makes it at the same time can allow to prepare formable sheet extrudates of different lengths This is especially convenient since the first length or mold segment is sealed and blow molded. Ru.

An embodiment of a hollow double-walled article made according to the invention can be seen by way of example with reference to the accompanying drawings. It will only be explained. In the drawing, FIG. 1 shows a side section of a first embodiment of a blow molding device with the infant segment in the open position. 2 is a side sectional view of the first embodiment with the mold segments in the closed position; FIG. is a diagram, and FIG. 3 is a front sectional view of the second embodiment looking into the mold segment.

1 and 2, a blow molding apparatus 10 extrudes a tubular formable sheet extrudate. A parison extruder 12 is included. The extruder has a screw feeding device 14 and an open an annular extrusion opening 16 for producing a thermoplastic parison 18;

A blow bottle 20 connected to an air supply (not shown) passes through the parison extruder 12. and extends coaxially within the extrusion port 16. The blowing bottle 20 is connected to the parison extruder 12 extends downward.

Also a parison cutting device! (not shown) is a parison extruder adjacent to the extrusion port 16. It is located below. The blow molding equipment is placed in a horizontal plane around a portion of the parison. a pair of bondable blow mold segments 30.32 adapted to close; Including further. In Figure 1, the blow mold segment 30.32 is depicted in the open position. (the support device has been omitted for clarity) and the blow molding in Figure 2. The mold segments are depicted in the closed position and clamped around the parison length. ing. Blow molding mold parisons 30, 32 themselves can be used as parison cutting devices. can act.

Each blow mold segment 30, 32 defines two halves of the screw neck bottle. The inner molding surfaces 34, 36 are grown respectively. At the top, each blow mold segment Ment 30, 32 are blown when mold segments 30, 32 are closed around them. Raise the upper half gate 38 to fit the bin. The downward blow bottle 40 is an upward blow bottle. It extends upward from a point below the pin 20 coaxially therewith. 30 each segment ．． 32 fits with the lower blow bottle 40 when M#I is applied to the pear segment or its brow. It has a lower half gate 42 at its bottom portion so as to.

The lower blow bottle 40 has a regulator (not shown) connected to the same air supply as the upper blow bottle 20. through which the regulator regulates the airflow through each blow bottle relative to each other; Applying the appropriate amount of air through the blow bottle, which will be explained in detail later with respect to Figure 3 The pressures can be equalized as described.

The nozzle 44 of the lower blow bottle 40 is inserted into the neck 48 of the preformed inner container 50. It has an outer surface 46 adapted to be received with a snug fit. Inner container 5 0 is held face down in and generally coaxial with the open necked parison. .

The surface 46 of the lower blow bottle nozzle 40 is located below the blow mold segment 30.32. The half gate 42 is positioned to mate with the neck 48 of the inner container 50. ing.

Inner container remote from neck 48 when positioned on lower blow bottle nozzle 40 The end 52 of 50 is near the upper blow bottle 20 but does not touch it.

As shown in FIG. is defined between the tube I8 and the inner container 50.

Generally, the lower blow bottle 40 is retractable so that one inner container 50 is 50, the inner container being coaxial with the parison outlet 50. can be manipulated to any position. One parison length then through extrusion 01B It is extruded around the inner container 50. Extrusion is done at the edge 56 of the parison or at the neck of the inner container. It stops when it becomes at least parallel to 48.

The mold segments 30.32 are then closed around the parison 18, thereby Cut the parison for extra length. Together define the threaded neck of the finished part The lower molding surfaces 58 and 60 adjacent the lower gate half 42 are located at the edges of the parison. Bringing its lower end portion adjacent to 5G into close contact with the neck 48 of the inner container; shrinks around it to form a common neck of the finished molding, hence the upward Seal the end of the parison remote from the blow bottle 20. Type segment 30.32 The upper gate half 38 closes around the upper blow bottle 20 and therefore closes that part of the parison. Seal the edges.

A fluid pressure medium, such as air, is passed through the upper blow bottle 20 into the now sealed annular cavity 54. The outer wall 60 of the finished article is introduced through the molding surface 34 of the mold segment. ．． Walls blown to 36 and thus joined at a common neck but forming a double-walled hollow article with an annular space between the walls elsewhere. . Also, a fluid pressure medium is introduced into the annular space 54 prior to sealing the neck 48. can be done.

The fluid pressure medium is also introduced into the interior 62 of the inner vessel through the lower blow bottle 40. This equalizes the pressure between the annular space 54 and the interior of the inner container 62. Annular void 5 Since the respective volumes of 4 and the inside 52 of the inner container are different, their pressures are equalized. This requires that the respective air blow rates be varied accordingly. child One arrangement for achieving an air volume difference of 1 is described in more detail with reference to FIG.

After the blow molding is completed and the outer container has been sufficiently cooled, air is drawn into the molded container. so that the respective pressures between the inner and outer vessels are maintained approximately equal to each other. to prevent distortion or rupture of the inner container. Mold segment 30.32 is here. , the lower blow pin is retracted together with the attached double-walled article. , remove the article from the upper blow bottle 20 and place it in the end of the container far from the common neck. to leave a hole in the outer wall 60. This pore can be Can be used to insert edge media.

The embodiment of FIG. 3 is similar in general concept, but with air flowing into the generally annular cavity between the walls. Molding a common neck between the inner and outer walls of the article adjacent to the hole into which the bottle is inserted; ing.

In FIG. 3, a front view of the split mold segment 70 is shown, with the inner container 72 in the first in a predetermined location on the blow bottle 74 of. Similar opposed split mold segments (as shown) ) defines a mold when closed onto mold segment 70. Figures 1 and 2 As in the embodiment, the neck 76 of the inner container is positioned over the nozzle 88 of the blow pin It fits and is accepted. A gate 78 of a type that receives the first blow pin 74 Adjacently, the threaded inner surface 90 of the mold closely holds the neck 76 in the closed position. Enclose and weld the neck to the parison. The mold segment 70 is A second blow pin 84 extends into the cavity 86 between the molding surface 90 and the molding container 72. It has another gate 82 for receiving. Between gates 78 and 82, each type segment The inner surface of the container allows the handle to be blown integrally with the outer container. It has a raised handle molded part that cooperates in a similar manner. Before closing the mold segment The position of the tubular parison is shown in phantom 92.

an inner container and a space defined between the inner container and the molding surface of the mold segment; Each volume is different. This during the subsequent air evacuation step of the blow molding step. Since it is desirable to equalize the pressure in each of the vessels, the device Pressure equalization that allows the air source to meter its appropriate amount of air into each space Equipment is installed.

The pressure equalization device includes a source of pressurized and filtered air connected to air line 94. nothing. Air line 94 connects a solenoid with outlet 100 and downstream line 102. Upstream of the directional valve 98 is an adjustable regulator 96 . The downstream line 102 is the first an inner vessel line 104 leading to a second blow pin 74 and a second blow pin 84 It branches into an outer container line 106. Inner container line 104 and outer container line The inlets 106 are each intermediate between its blow pin and its connection to the air line 94. flow control valves 108 and 110, respectively. Flow control valves, two-way valves and regulation The vessel is shown schematically in this figure. Flow control valve 108, ]]0 indicates the blowing direction and Each acts to independently regulate airflow in both directions of discharge.

To further meter the respective amounts of air applied from each blow bottle 74 and 84 , the inner 104 and outer 106 air lines are each in the form of an adjustable piston structure. There are variable volume chambers 112 and 114, respectively. Therefore, the inside of the inner container 72 The volume difference between the inner container and the space between the inner container and the forming surface 86 is determined by the appropriate volume of each variable volume chamber. be compensated for by appropriate adjustments so that these during blow molding and subsequent evacuation are can be used to allow pressure equalization within each of the spaces.

In FIG. 3, the volume of variable volume chamber 112 associated with inner container blow bottle 74 is The variable volume chamber where the stone 116 is near the end of its stroke and with the air line 104 is relatively small when placed adjacent to the connecting portion 118 of the. In contrast, the inner container and Less air is blown into the relatively small space 86 defined between the forming surface. The variable volume chamber 114, which measures a quantity that is not measured, is configured to define a relatively large volume. The piston 120 is grown. Each tuner is suitable for a particular common air input pressure. The node can be set empirically or by an arithmetic calculation of the difference in the amount of air blown. It can be set as follows. This configuration of the pressure equalization device allows it to and the air pressure in the outer vessel, while using a single source of air pressure. It is especially convenient to use. Furthermore, variable volume chamber 112,114 and flow control valve 1 08.110 can be adjusted independently, so the device can accommodate different volumes and The invention can be adapted to blow mold hollow, multi-walled articles of various shapes.

Adjustment of the amount of fluid pressure medium metered through each blow bottle is carried out in the inner container and in the inner volume. It was discussed in connection with the pressure equalization achieved between the container and the parison. However However, the pressure required in each space can be determined, especially if the strength of the inner container is known. Minor modifications can be tolerated and the variable volume geometry described here or can be used.

Typically, forming a double-walled article according to the second embodiment includes a preformed inner container. 72 on the first blow pin 74 adjacent to the second blow pin 84. can then be extruded elsewhere and supported by cutting scissors. The parison length can be manipulated over and lowered around the inner container 72. Ru. The mold segment 70 is then closed around the parison, resulting in a double walled a double article whose common neck has a neck around the circumference of the first blowing bottle and a cavity between the walls; The double-walled hollow article is blown through the hole left in the outer wall after the blow 84 is drawn in. It can be introduced into the same cavity in the wall.

- Alternatively, this double-walled article may itself be used for another application of the method and apparatus of the invention. When used as an inner container for The hole is applied through its neck 76 to the blow-molded inner container 72 of the outermost container. can be used to apply fluid pressure media in addition to Ru. In this alternative application of forming multi-walled articles, the neck of the innermost container and the intermediate container It is particularly advantageous to provide a blow bottle for blow molding the outermost container at the far end of the container. Sometimes it is convenient.

The described embodiments are offered for illustrative purposes only, and many modifications may be disclosed herein. The spirit and scope of the invention, including each novel feature and combination of novel features, can be done to it without departing from it.

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Claims (23)

[Claims] 1. An inner container having a neck and a hollow body is juxtaposed with the formable sheet extrusion. A method for blow molding a large volume hollow article with walls, the method comprising: The segments of the split mold are closed onto the extrudate, leaving a nearly sealed parison in the mold. formed around the body of the inner container such that the annular end portion of the parison extends around the neck of the inner container. extending closely to the a fluid pressure medium is applied to the space defined between the body of the inner container and the parison; In a method of forming a blow molded outer container, The interior of the inner container is pressurized with a fluid pressure medium during blow molding of the outer container. How to do it. 2. In the space defined between the body of the inner container and the parison and inside the inner container 2. The method of claim 1, wherein the pressures of each of the two are maintained substantially equal during blow molding. . 3. A single fluid pressure medium liquid is used and the volume between the interior of the inner container and said space 2. A method as claimed in claim 1, in which the difference is compensated. 4. To achieve said compensation, each of the inner vessels with a single fluid pressure medium source a fluid pressure medium within or between the inner container and the space defined between the parison; 4. The method of claim 3, wherein each of the flow paths is provided with a different volume. 5. The different volumes are defined by variable volumes associated with at least one of the flow paths. 5. The method according to claim 4, which is accomplished by: 6. An insulating medium is formed in the cavity defined between the body of the inner container and the blow-molded outer container. 2. The method of claim 1, wherein the method is injected into the medium. 7. The insulating medium is less of the fluid pressure medium used to blow mold the outer container. 7. A method as claimed in claim 6, wherein the method also forms part of. 8. Closing the split segment welds the ring area of the outer container to the neck of the inner container. 2. The method according to claim 1. 9. The inner container defines a plurality of internal cavities, each internal cavity having a respective neck. and each cavity is pressurized with a fluid pressure medium during blow molding of the outer container. method. 10. The space defined between the body of the inner container and the parison has a ring around said body. 2. The method of claim 1, wherein the method comprises: 11. A hollow multi-walled article produced by the method of claim 1. 12. An apparatus for producing a hollow multi-walled article, the apparatus comprising: An apparatus for extruding formable sheet material and an inner container as well as a formable sheet extrudate. an apparatus supported in positional relation, an inner container having a neck and a hollow body; Place the nearly sealed parison in the mold so that it closes onto the extrudate. The annular end portion of the parison forms around the neck of the inner container. A split mold segment extending in close proximity to the inner vessel body and a split mold segment that transfers fluid pressure between and a device that blow-molds the parison onto the mold by applying a voltage to the space defined between the mold and the mold. In a device including, The method further includes a device for applying fluid pressure to the interior of the inner container during blow molding of the parison. A device characterized by: 13. A claim in which the device supporting the inner container is a blow pin passing through the neck of the inner container. The apparatus described in item 12. 14. A single fluid pressure medium source supplements the end fluid pressure utilization device and connects the interior of the inner vessel. compensate for the volume difference between the inner container and the space defined between the mold segments; maintaining respective desired pressures within each of said interior and said spaces by 13. The apparatus of claim 12, further comprising an apparatus. 15. a single source of fluid pressure medium and the internal cavity of the inner container, or the body and mold of the inner container; The spaces between the segments and the intermediate respective fluid pressure medium flow paths are different. 15. The apparatus according to claim 14. 16. 16. At least one of the flow paths comprises a variable volume device. equipment. 17. fitted with an inner container defining a plurality of internal cavities to direct fluid pressure to said cavities. 13. The apparatus of claim 12, including means for applying voltage to each. 18. Extrusion outlet of extrusion equipment for juxtaposition of formable sheet extrudate with inner container The apparatus according to claim 12, further comprising moving scissors or nippers for conveying away from the Place. 19. The extrusion device is an annular extrusion device arranged concentrically above the device supporting the inner container. 13. The device of claim 12, including an outlet. 20. Applying fluid pressure to the space defined between the body of the inner vessel and the mold segment 13. A device according to claim 12, wherein the device extends into or opens into the mold adjacent to the support of the inner container. Equipment described. 21. Applying fluid pressure to the space defined between the body of the inner vessel and the mold segment 13. The device according to claim 12, wherein the device extends or opens into the mold remote from the support of the inner container. Equipment described. 22. Injecting the insulating medium into the space defined between the body of the inner container and the mold segment 13. The apparatus of claim 12, comprising an apparatus for: 23. The insulating media injection device applies fluid pressure between the body of the inner container and the mold segments. Claim 2 in communication with a fluid pressure medium flow path of a device for applying pressure to a space created. The apparatus described in 2.