JPS58208022A - Blowing molding device and its method - 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 Technical Field: The present invention relates to blow molding technology of thermoplastic materials. More specifically, the present invention describes the use of blow molded articles made from typically highly transparent thermoplastic materials such as polypropylene, which must be biaxially oriented to achieve desired properties such as strength and clarity. The purpose is to provide methods and means for

BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION The production of hollow products, such as containers such as bottles, from thermoplastic materials has been carried out by blow molding. This method is.

It is carried out through a continuous tube in which the thermoplastic material is injected, cooled to crystallize it, and then heat treated. Examples of such heat treatments are:

U.S. Patent No. 26,956, No. +3,496,258
No. 3,677,530.

One method: in this case, at its orientation temperature, a section of the tube is cut and the cut section (hereinafter referred to as pariso) is gripped by its ends.

It had expanded in the vertical direction t5 and died. When the parison is placed in its extended state, the mold piece of the blow mold closes the tube, which then closes.

Air was blown into the container and allowed to expand to form the desired product body. The mold piece is that t! The drilled and formed body is removed and the cycle is repeated. This method has various drawbacks, including poor production efficiency;

The second blow molding method is a method in which the tube itself is basically left untouched. In this method, a longitudinally elongated and blow-molded technique called the 6H/do-over-hand technique is used, which results in a chain consisting of a hollow body of the product in any desired shape. No. 3,699,199; No. 3,704,188;
．． No. 798,295, No. 3,751,542 and No. 3
．． No. 834,852. In this example, two movable blow molds are included.

The mold piece of the first blow mold closes the tube in its first position, after which the blow mold
It is moved by a predetermined distance and moved to a second position. During this movement of the mold, that part of the tube within the blow mold is inflated to the shape of the mold cavity, and the part of the tube leading to the blow mold is moved from the first point to the second point. be tempted to draw. Throughout the tube pulling process or within a predetermined time period thereof, the movement of the tube past the first point is prevented by a restriction cone or clamp, so that the portion of the tube between the two points The mold is stretched vertically until the second point is reached. Meanwhile, a second blow mold having two mold pieces is opened and the mold piece is returned from the second position to the first position, straddling the closed first blow mold. . Then, the portion of the tube that has been overlaid in step 1 is closed in the mold piece of the second mold.

The mold section of the first blow mold is opened.

The closed second blow mold is then moved to the second position 16, thereby transferring the wetted body to the open 9 of the first blow mold.
It is pushed out from between the two pieces.

At the same time, the next section of the tube is pulled from the first position to the second position. The passage of the tube through the first point throughout the drawing process causes it to be elongated in the longitudinal direction until such time as the second blow mold reaches the second position. As with the first blow mold, during this forward movement of the second blow mold, the stretched portion of the tube located within the mold is forced to flex to match the shape of the mold cavity. The body is blinded, thereby forming a body and causing the material of which it is constructed to be oriented in two axes. The blow-molded body extruded from between the open mold sections of the first blow-mold is joined by the previously formed chain of linked blow-molded bodies by the unexpanded portion of the tube. is connected to. The chain is conveyed from the molding equipment to a final processing location where the bodies are separated, processed, and the mouth or neck or other opening of the product is punched or cut to create the final product.

The apparatus and method of the present invention relates to an improvement in the ``...undo-over-to-hand type apparatus and method.

SUMMARY OF THE INVENTION: A blow mold molding according to the invention is adapted to receive a continuous tube of thermoplastic material which is not biaxially oriented, but which is normally highly transparent at its orientation temperature. This is a device in which the tube is formed into a chain of a hollow product body made of biaxially oriented material, and the chain of the body is discharged.

The device of the present invention is a tube/chain moving means.

Constructed with a tube brake, and a stationary blow mold assembly included. It is composed of a tube/chain moving means, a tube engaging means, a shuttle, and a shuttle main mover.

The shuttle moves back and forth between the first position and the second fn', iiJ by a seven-yatle main mover. The tube engaging means is supported by the shuttle and grips the tube when the shuttle moves forward.

Zhang Kai pulls the tube from the first point to the second point, and pushes the part of the chain consisting of the hollow-shaped product body formed between the two points beyond the second point;
The mold piece of the stationary blow mold assembly then acts to open the tube after closing the portion of the tube between the two points.

The tube brake brakes movement of the tube past the first point during at least a portion of the time that the tube is pulled to the second point, thereby braking the movement of the tube past the first point. means for longitudinally extending the portion of the tube between the tubes. In one embodiment of the invention, the brake means comprises a restriction cone through which the tube passes. However, in a preferred embodiment of the invention, the tube brake comprises:
It consists of stationary clamping means. The jaw member is movable by a main mover for the jaw member from a tube engaging/grasping position to an open position.

Between the two points, the stationary blow mold assembly
It consists of at least one stationary blow mold. In one embodiment of the invention, one blow mold is provided, whereas on the preferred side; ζ, multiple blow molds are provided. Each blow mold in the assembly is comprised of at least two mold pieces.

At least one of the mold pieces is movable from a closed position adjacent the other mold piece to an open position spaced from the other mold piece. The distance between both mold parts in the open position is
A tube is passed between the mold pieces and can be pulled from the first point to the second point, and a hollow-shaped product body formed in the mold can be extruded from the mold. It is assumed that the interval is In their closed position, the mold pieces adjoin each other and define a cavity therein having a shape equal to the outer shape of the product body to be blow molded. Primary mover means are provided for moving one or both of the mold pieces from their open position to their closed position. The primary mover means may be a reversible motor, an air or fluid actuated piston/cylinder assembly. The blow mold is further adapted to inject air into the portion of the tube within the mold cavity after the mold piece is closed over the portion of the tube extending longitudinally between the two points. Preferably, the surface of the mold piece is configured to pinch the ends of the elongated tube section within the cavity to form an airtight seal, thereby:
Air is removed from the mold cavity, air is introduced inside the tube section within the cavity, or both are performed to inflate and inflate the section 7a/ to a shape that matches the shape of the cavity.

Each mold piece has a 1" 1 through the inner part of the mold.
It is preferable to have passages for circulating a cooling medium, thereby cooling the wall surface t of the inflated hollow product body to a temperature at which the tube material hardens, ie becomes plasticized. Furthermore, the blow mold uses a screw-in cap.

It is preferable to include a screw forming means for finishing a kinematic bottle with a screw or the like.

In normal operation of the device of the present invention, the distance between the two points,
The speed at which the tube is pulled by said tube/chain moving means, whether cold air is applied to said tube by a limiting cone or by stationary gripping means or by other means, is determined by the speed at which said tube is pulled to said second point. The portion of the tube located between the two points is then selected to be stretched in the longitudinal direction, preferably to a length such that the material of which the tube is made is oriented in the longitudinal direction.

The operating cycle of the device of the invention consists of a tube/chain transfer phase, a blow mold phase, and a blow mold opening phase. At the beginning of the tube/chain movement phase, the mold pieces of the stationary blow mold assembly are left in place.

and the tube/chain moving means is in its first position. The tube engagement means are configured to grip the tube, preferably in the region of the first point. With the tube so gripped, the moving means moves toward its second position, thereby pulling the tube from the first point to the second point and pulling the tube between the two points. pushing said portion of the chain formed beyond said second point. In embodiments where the tube brake is a restriction cone.

The tube immediately begins to be stretched longitudinally. In embodiments where the limiting tube brake includes movable jaws, the jaws move into gripping engagement with the tube;
This stops the movement of the tube past the clamp section. The tube then begins to elongate in the longitudinal direction. When the moving means reaches its second position, the mold piece of the stationary blow mold assembly closes off the longitudinally extending portion of the tube between the two points.

The tube portion within each cavity is then inflated by injecting air, evacuating air within the cavity, or both until the tube conforms to the shape of the cavity. On the other hand, when the mold piece is closed over the elongated portion of the tube, the tube engaging means of the moving means releases the outer tube and the moving means returns to its first position. The mold piece is then opened and the above procedure repeated.

In embodiments of the above apparatus in which the stationary blow mold assembly comprises a number of stationary blow molds, there is a tendency to cause the chain to snap back when the mold sections are opened. This is mainly due to elastic shrinkage and shrinkage due to temperature drop. To minimize this effect, in preferred embodiments, the mold pieces are opened continuously. More preferably, they start with the stationary blow mold closest to the second point and continue with the adjacent molds. In those embodiments where more than one stationary blow mold is provided, the next adjacent stationary mold is drilled, and so on, continuing to the stationary blow mold closest to the first point.

In embodiments where the stationary blow mold assembly consists of a large number of stationary blow molds, the greater the number of blow molds, the longer the length of the chain formed between the two points. I see, tube/
When the chain moving means moves from said first point to said second point, the tendency of said chain to sag increases.

Such chain flexure prevents the chain from being pulled beyond the second point. Consequently, in a preferred embodiment of the invention, chain support means are preferably provided for supporting the chain while it is being pulled beyond said second point. In a preferred embodiment of the invention, the chain support means comprises:
It consists of a movable rondo. This Rondo is
Tube/.11 When the chain moving means is in its first position and the mold piece is closed to the elongated part of the tube, it is located under the outer tube part of the blow mold. Being able to do so. That is, the links of the chain are located below the links after the mold piece has been opened and the moving means has moved from the first position to the second position. The rond is also movable so as not to contact the closed mold piece when the moving means moves from the second position to the first position.

DESCRIPTION OF THE EMBODIMENTS: Referring to FIGS. 1-7, there is shown a blow molding apparatus 20 for forming a chain 21 of bottle bodies 22 having threaded sections connected by links 23. The bottle body is made of a normally highly transparent thermoplastic material that is biaxially oriented at its orientation temperature; continuous tube 2
Manufactured from 4.

Blow mold apparatus 20 is comprised of a support structure 26 on which a working tube and chain moving device 27 is mounted, a stationary tube brake 28 - and a blow mold assembly 29 . The tube and chain moving means (see FIGS. 1 and 2) includes a tube gripping member 30, a shuttle 31, and a main mover (only a portion of which is shown).

Tube gripping member 30 (see FIGS. 8 and 10) includes a pair of jaw-like members 33 that are swingably attached to shuttle 31. As shown in FIGS. The jaw member is opened and closed by a main mover 34 of the jaw member. In this embodiment, the main slider 34° of this jaw-shaped member is composed of a combination of an air cylinder, a piston, and a piston rod. The shuttle 31 is attached to the upper longitudinal bar 3 of the support structure 26.
5 and a flat plate slidably attached to the lower part 36. The main translator consists of a longitudinal piston rod 32 of a pneumatically or hydraulically driven piston/cylinder assembly. The cylinder of the piston/cylinder assembly is mounted stationary in front of the blow molding apparatus.

In this embodiment, the tube brake 28 (see FIG. 9) includes a pair of jaw-like members 41, a main slider 42 for these jaw-like members, and a support plate 43. There is. This jaw-like member 41 is swingably mounted on the support plate 43 and is positioned in the front portion of the blow molding device 2o so as to close the tube 24 and have a gripping relationship therewith. The jaw-like member 41 is opened and closed by the main mover 42.

In this embodiment, the j-translator 42 is an air cylinder/piston rod assembly connected to jaws at both ends thereof. The support plate 43 is fixed to the support structure 26 of the blow molding device θ20.

Stationary blow mold assembly 29 includes a number of stationary blow molds 50 (see FIG. 2). In this embodiment, each stationary blow mold 50 includes an upper mold piece 51 and a lower mold piece 52. The upper mold piece 51 is attached to a longitudinal bar 53 of the support structure 26, while the lower mold piece 52
teeth.

It is laterally rotatably mounted on a longitudinal bar 54 of the support structure. Instead of being positioned above and below the travel path of the tube 24, in other embodiments of the invention, two mold pieces are each provided on either side of the travel path when they are in their open position. It can be done. At this time, the other structural components of the blow molding apparatus are appropriately arranged. In either embodiment, the blow mold piece defines a cavity that conforms to the outer shape of the bottle body 22 when in its closed position. Additionally, the surface of the blow molded piece is
When they are closed onto the tube 24, the end portions of the tube located inside the closed mold piece are pinched to provide a permanent airtight seal.

to be shaped. In the illustrated embodiment, each stationary blow mold has a thread forming/neck gripping device 5a5 (only a portion of which is shown in FIG. 1), as the molded product has an external thread on its top. (shown schematically) are provided. Such a device 55 is
For example, U.S. Patent No. 3,834,8 issued to Ball
It is disclosed in No. 52. In this embodiment, each mold section is provided with an air blowing pin 56 extending into the tube and extendable for blowing air into the tube section within the closed mold section. ing. The mold piece is also laterally expanded while the tube is blown with air through an air blow bottle 56.

Exhaust holes 59 (see FIG. 1) are provided to vent any air that may have been between that portion of the tube and the wall of the mold cavity. Additionally, the mold piece has internal passages for circulating a cooling medium. These passageways are provided through end fittings.

It is connected to a cooling medium hose (not shown).

The mold member is moved by a main slider 57 (FIGS. 2, 8, and 10) such that the mold piece swings from its open position (see FIG. 8) to its closed position (see FIG. 10). (see) is bonded to 4 phosphorus. In some embodiments of the invention, the main mover may be a reversible motor; in this embodiment, the main mover 57 is.

It consists of an air cylinder, a piston, and a hipistonrond assembly.

The chain moving means 27 constitutes a chain moving device 6o together with the tube gripping member 3o. This is a device (see FIGS. 1, 2, and 11) that includes a front support plate 61 and a back support plate 62. These two support plates are slidably supported by upper and lower longitudinal displacement means support rods 35 and 36.

The front support plate 61 is provided around the upper vertical rod 35 and is attached to the shuttle 3 by a cylindrical spacer 63.
1. Similarly, back support plate 62 is spaced apart from front support plate 61 and connected thereto by an intermediate structure.

In situations I where the longitudinal length of the blow molding device is not a problem, this intermediate structure can be a second shilling-shaped spacer. However, in the illustrated embodiment, which is particularly useful in environments where space limitations are imposed on the reservoir of a blow molding apparatus, the intermediate structure is located at the second position ( (see FIG. 3), the chain moving device 60 can be disassembled in the longitudinal direction. That is, the intermediate structure is provided with an air cylinder 66 having an internal piston and a piston rod 7 mounted in the longitudinal direction on the front support plate 61 and arranged laterally on the front support plate 61 . piston rod 6
7, in its fully extended position (see FIGS. 2 and 11), is arranged as a chain support bin below the chain link 23 between the closed first and second stationary blow molds 50. It is being A second pneumatic shilling with an internal piston and a telescoping piston rod, i.e. a chain support bin 69.

68 is laterally attached to back support plate 62 (see FIG. 2). The connecting rod 65 is fully extended from the vertical air cylinder 63 mounted on the front support plate 61 and the shuttle 31 is in its first position at the beginning of the mold reciprocating ring phase of the normal operating cycle of the apparatus. When in position , support bin 69 is extended and positioned below chain link 23 between the last two blow molds 50 in blow mold assembly 29 .

The illustrated blow molding device 20 is adapted for use with an endless belt conveyor 75 for discharging the chain 21 comprised of the illustrated bottle bodies 22. The front end of the conveyor 75 is attached to a bracket 76 on the support structure 26 in the area of the last stationary blow mold 50 of the blow mold assembly 29.

Blow molding apparatus 20 is a continuously operating apparatus with each cycle of operation consisting of three basic stages. The first stage is the tube tension V/stretch stage (which also doubles as the chain extrusion stage) (see Figures 1 and 2). The second stage is the blow mold stage (see Figures 4 and 5). And the third stage is
This is the stage of opening the stationary blow mold (see Figures 6 and 7).

At the beginning of the first stage, the upper and lower mold pieces 51 , 52 are in their open position and the chain moving means 27 is located on its front side in a position in which its rear support plate 62 extends from the front support plate 61 . It is located at the end position. The jaws 33 of the tube gripping member 30 supported by the chain moving means 27 are in their closed position and hold the tube 24 of substantially biaxially non-oriented thermoplastic material at its orientation temperature. I'm holding it. The chain moving means 27 is then pushed into its second position (see FIG. 3) by the rod 32 of the main mover, thereby pulling a predetermined length of the tube 24 into the blow molding apparatus 20 (and at the same time The belt conveyor 75 is started. When the tube gripping member 30 is approximately one-third of the way through its longitudinal travel, the brake jaws 40 close the tube, thereby causing the chain moving means 27 to move from its position. When the second position (see FIG. 3) is reached, the portion of the tube starting from the tube brake 28 (position A) and dividing by i at the second stop position (position B) of the tube gripping means 30 is: In the longitudinal direction, preferably the material of the tube is stretched to a length oriented in the longitudinal direction.At about two-thirds of the distance of travel of the tube gripping means, the material of the tube is stretched onto the rear support plate 62 of the chain moving device 60. The chain support bin 69 provided in the chain support bin 69 is retracted and the air in the vertical air cylinder 64 is evacuated.

Thereby, the connecting rod 65 is retracted, allowing the chain travel left 60 to disassemble longitudinally when it reaches the rear end of its travel distance. When the chain moving means 27 reaches the second position, the support bin 67 provided on the front support plate 61 of the chain moving device 60 is retracted and the conveyor 75 is stopped. This completes the first stage of the operating cycle of the device.

In the second phase of the operating cycle of the device of the invention, the mold piece is closed over the stretched portion of the tube 24 between points A and B (see FIG. 4), and the chain moving means The tube invitation member 30 at 27 is raised such that its jaws 33 are removed from the aligned position of the closed mold pieces 51 and 52 of the stationary blow mold 50 (see Section 1, Section 1). Chain moving means 2
7 is.

Then pull it back to the first position at the front of the device. On the other hand, the vertical cylinder 64 on the front support plate 61 is pressurized to extend the connecting rod 65, causing the chain moving device 60 to extend in the longitudinal direction. The chain moving means 27 is the first f! When returning to δ, the back support plate 62 is positioned below the link 23 where the chain support pin 69 is located between the last two static blow molds 50 of the stationary blow mold assembly q body 29. It is positioned as if it is stretching out. Meanwhile, the chain moving means 27 is returned to its original starting position and inserted into the stretched portion of the tube 24 located in the air blowing bottle 561 emold in the respective stationary blowing mold 50. The pressurized air passes through bottle 56 to inflate the portion confined within the mold, expanding it to a shape matching that of the mold cavity and actuating the thread forming, neck gripping device 55.

At the beginning of the stage of opening a stationary blow mold, the chain support bins 67, 69 are extended and then starting from the blow mold closest to the second stop point B and then to the first blow mold closest to the first or starting point A. The molds are opened one by one one by one in the direction of the blowing mold (see Figures 6 and 7).

When all stationary blow molds have been opened.

The operation cycle is complete.

As mentioned above, the blow molding apparatus according to the present invention inherently has high productivity. The limit on the number of blow molds is such that when the tube 24 is pulled and stretched, the weight of the tube between points A and B will not cause the tube to sag beyond the allowable range. The only restriction is that you must want to do so.

Therefore, the blow molding apparatus and method of the present invention have significant advantages over the "no-do overhand type apparatus and method of the prior art."

[Brief explanation of drawings]

FIG. 1 is a side view of one embodiment of a blow molding apparatus according to the invention, showing the positions of its various movable members just before the beginning of the tube pulling and chain extrusion stages during a normal operating cycle of the apparatus; There is. 2 is a plan view of the apparatus of FIG. 1; FIG. FIG. 3 shows the first part of the apparatus according to the present invention, with some parts omitted.
Figure 4 is a side view similar to the Figure showing the movable member and tube 24 at the end of the chain extrusion and tube tensioning stages of the operating cycle of the device. FIG. 5 is a diagram similar to FIG. Figure 6 shows the position of the moving parts at the end of the blow molding stage; Figure 6 is a side view similar to Figure 1 of the apparatus of the invention;
Figure 2 shows the position of the moving parts just after the blow mold opening phase of the operating cycle of the device has begun; FIG. 7 is a similar side view of one apparatus of the present invention, showing the position of the moving parts at an intermediate point in the mold opening stage. FIG. 8 is a cross-sectional view of the apparatus of the present invention taken along line 8--8 of FIG. FIG. 9 is a cross-sectional view of the apparatus of the present invention taken along line 9--9 in FIG. FIG. 10 is a cross-sectional view of the device of the present invention taken along line 1 (1-109) in FIG.
11 is a cross-sectional view of the device of the present invention taken along line 11-11 of the figure; FIG. 20... Blow molding device 22... Bottle body 2
・1...Tube 27...Chain moving means 28
...Tube brake 31...Shuttle 33...
・Continued priority claim for jaw-like member patent on page 1 of Hercules Inc.
S) @367140 [Phase] March 8, 1983 [Phase] United States (US) @473
291 0 Inventor Larry Uniin English United States of America 47805 Chill Auto Route 52 Box 386 Procedure → Orthographic Axis Pass 111 items. 7 years ago 1962
Pattern number 7:・t i+, t No. 25 Denmei” (7
) syu devised 5th start-! ≧-7--, 2 coins Jφ 3 Yome-Lj shi 3 amendments to Redoi Relationship with the case Applicant address 7.1 do (/l/-λ)・-b Luz ia・Ku Hands'-7・F"4, Agent

Claims (1)

[Scope of Claims] (1) A thermoplastic material that is normally extremely transparent and biaxially oriented at its orientation temperature, which is a continuous continuous material made of the above-mentioned material in a substantially unoriented state. In Tanu's blow molding machine, which forms a chain consisting of a hollow-shaped product body made from a tube, the part of the chain provided between the first and second points is pulled past the second point. tube/chain moving means for pulling the tube from the first point to the second point; braking the movement of the tube past the first point during a portion of the time that the tube is being pulled; and tube braking means for applying and thereby elongating the tube section between said points. a mold piece capable of closing the elongated portion of the tube, the mold piece being adapted to form a hollow body within a cavity defined by the closed mold piece; and means adapted to inflate the elongated ledge of the tube within the mold cavity, thereby forming one of said bodies of biaxially oriented material therein. A blow molding device comprising: blow molding means. (2) In the blow molding device according to claim 1. said tube/chain moving means moves said moving means from a first position to a second position, thereby pulling said tube from said first point to said second point;
and holding the tube while extruding the portion of the chain formed between the two points beyond the second point, and the stationary blow mold piece is placed on the elongated portion. tube engaging means configured to open the tube after the tube is closed; and main mover means for moving the tube engaging means back and forth between the first and second points. A blow molding device comprising: (3) The blow molding apparatus according to claim 1, wherein the stationary blow molding means is constituted by main moving means for opening and closing the mold parts. (4) In the blow molding apparatus according to claim 3, the stationary blow molding apparatus comprises a plurality of stationary blow molds disposed between the first and second points. A blow molding device consisting of: (5) Particular 1. Scope of punching and testing In the blow molding apparatus set forth in item 1, the formed chain portion between the two points described in (1) above is
A blow molding apparatus comprising chain support means for supporting the chain section until it is extruded beyond the point. (6) A blow molding apparatus according to claim 5, wherein the chain support means is adapted to be combined with the tube/chain moving means. (7) In the blow molding apparatus according to claim 5. The chain support module is configured to support at least one of the portions of the chain during the step of opening the mold piece and during at least a portion of the distance of movement of the moving means from a first point to a second point. Retractable means can be located below the link and adapted to be stretched so as not to engage the closed mold piece during movement of the moving means from the second position to the first position. A blow molding device consisting of: ...11111 (8) Percentage of Claims''□ The blow molding device according to claim 7, wherein said extendable means is used in conjunction with a piston of a fluid-operated cylinder mounted on said moving means. A blow molding device comprising a piston rod disposed in the direction of water flow. (9) In the blow molding device according to claim 8, The bottom of the chain link formed between the first two stationary blow molds follows J
A blow molding device adapted to be able to be located at j. In the blow molding apparatus according to clause 9, the telescoping means are formed between the last two stationary blow molds before the second bend. V together with the piston of the hydraulic actuator/cylinder provided on the moving means so as to be located below the links of the chain;
A blow molding device comprising a second piston in the water/collar direction, adapted to be used in C. (11) It was made from a tube of the above-mentioned material, which is normally a highly transparent thermoplastic material and is in an unoriented state at the iEl temperature. It had a hollow shape and was oriented in two axes. In a continuous blow molding method for forming a chain consisting of a product body. pulling said tube from a first point to a second point, and said portion of said chain formed between said two points;
pushing past the second point; braking the movement of the tube past the first point for at least a portion of the time that the tube is being pulled, thereby increasing the distance between the two points; elongating the portion of the tube located; closing the elongated portion of the tube with at least two corresponding mold pieces constituting a stationary blow mold; the mold formed by the mold pieces; inflating the elongated portion of the tube located within the cavity, thereby forming at least one body therein;
A blow molding method comprising: biaxially orienting the material; and opening the mold piece. (1) A method according to claim 11, comprising: closing said elongated portion of said tube by a number of corresponding mold pieces constituting a stationary blow mold; inflating the elongated portion of the tube located within a mold cavity defined by the pieces, each forming and configuring one of the bodies therein; (13j) In the method according to claim 12, the method comprises the steps of: orienting the material in two axial directions Q; and opening the mold piece. The closed mold pieces constituting the closed blow mold can be opened sequentially following the expansion step to minimize snap banking of the chain. (Claim 141) 13. The method according to claim 13, wherein the closed mold sections are successively opened from the side of the stationary blow mold closest to said second point. 13. The method of claim 12, wherein the portion of the chain between the two points is supported until it is pushed beyond the second point. Method.