JPH0661833B2 - Preform crystallization part forming method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for molding a crystallized portion of a preform made of a polyester resin having a crystallized bottom portion, and an apparatus therefor.

[Prior Art] A stretched polyester container molded by biaxial stretch blow molding is currently widely used as a container for various contents because of its excellent transparency, impact resistance, lightness, and the like.

However, in this stretched polyester container, the neck portion and the bottom portion were not stretched or were insufficiently stretched.

That is, since the neck portion is originally a portion that is not blow-molded, it is non-stretched. Therefore, the neck portion is heat-treated and crystallized at the stage of preform to impart mechanical strength and heat resistance.

On the other hand, in the case of molding into a container, there was a problem in that the vicinity of the gate at the bottom of the preform was not sufficiently biaxially stretched even by blow molding, resulting in poor mechanical strength and heat resistance at the time of temperature rise. Therefore, in order to strengthen the bottom of the container, a method of previously heating and crystallizing the bottom at the stage of preform has been proposed (JP-A-62-39443, JP-A-62-193938, etc.).

[Problems to be solved] In this way, the bottom part is crystallized at the stage of preform,
The container obtained by subsequent blow molding can enhance rigidity, mechanical strength, and heat resistance in the central region of the container bottom,
It is possible to reduce the thickness of the bottom portion, and it is possible to reduce the amount of materials and the weight of the container.

However, since the bottom of the preform is the part where the tip of the draw rod comes into contact during stretch blow molding, if the rigidity increases and is smoothed by crystallization, the end of the draw rod tends to slip. In many cases, misalignment occurs. As a result, even when stretch blow molding is performed with the stretch rod in contact with the bottom of the preform, the stretch tends to become non-uniform, resulting in deformation of the product or partial strength reduction. .

The present invention has been made in view of such problems, and by forming a recess for positioning the stretch rod in the bottom crystallized portion, it is possible to prevent the displacement of the stretch rod in stretch blow molding and to obtain a high quality product. An object of the present invention is to provide a preform crystallization part forming method and a preform forming part which can easily obtain a bottom part crystallization preform capable of producing a stretch container with high yield.

[Means for Solving the Problems] In order to achieve the above object, a crystallization part forming method of a preform of a first invention is to form a bottomed cylindrical preform by injection molding, and then to form a bottom part of the preform. The preform in the molten or semi-molten state is heated and melted, and the inner bottom portion of the preform in a molten or semi-molten state is pressed by a molding member to form a recess in the inner bottom portion, and then the preform bottom portion is cooled to be crystallized. It is as a configuration.

The preform crystallization part molding method of the second invention is that a cylindrical bottomed preform is molded by injection molding, the bottom part of this preform is heat treated and then cooled to be crystallized, and then this preform is crystallized. The bottom portion of the reform is heat-treated again to be melted, and the inner bottom portion of the preform in a molten or semi-molten state is pressed by a molding member to form a concave portion in the inner bottom portion, and then the preform bottom portion is cooled. Then, it is recrystallized.

The preform crystallization part molding method of the third invention is to manufacture a mold having a convex part at a portion forming the inner bottom part of the preform, and inject the molten polyester resin into the mold to inject the bottom part. A preform having a recess is molded, then the bottom of the preform is heat-treated, and then the bottom of the preform is cooled to crystallize.

The preform crystallization part molding device of the fourth invention is a preform molding means for molding a bottomed tubular preform,
A transfer means for transferring the preform taken out from the preform molding means, a heating means for heating the bottom portion of the preform transferred by the transfer means, and a heating or heating state by the heating means, which is in a molten or semi-molten state. A receiving member that supports the outer surface of the bottom of the preform, a molding member that is disposed so as to face the receiving member, and has a protrusion for forming a recess at the tip, and the preform that cooperates with the receiving member and the molding member. And a drive means for forming a recess at the bottom of the.

In addition, in the present specification, the “recessed portion” includes an uneven portion,
That is, it is used to mean that it has a recess.

[Operation] According to the preform as described above, the stretch rod can be positioned during stretch blow molding, and uniform blow molding can be performed. Further, according to the preform molding method and the apparatus therefor, it is possible to easily and surely form the concave portion in the bottom portion in the step of molding or crystallizing the preform.

[Examples] Examples of the present invention will be described below.

First, an example of a preform molded according to the present invention will be described.

FIG. 1 is a vertical sectional view of a preform, and FIG. 2 is a vertical sectional view showing the outline of stretch blow molding.

The preform W is made of polyester resin and has a bottomed tubular shape. The bottom of the preform W is a recess W ₁ from the inner surface side to have a crystallization unit W _S over a range, further the crystallization unit W _S.
The recess W ₁ is formed in a mortar-like shape over almost the entire area of the crystallized portion W _S centering on the central portion of the bottom of the preform W.

When stretch-blow-molding the above preform W, as shown in FIG. 2, the engaging projection having the top portion of the shape which is curved at a radius slightly smaller than the recessed portion W ₁ at the center at the tip portion of the stretching rod 601 is engaged. By forming the portion 601a and engaging the engaging convex portion 601a with the concave portion W ₁ ,
Reliable positioning (centering) of the stretching rod 601 can be performed.

Next, a preform crystallization part forming system including the fourth invention device will be described.

3 is an overall schematic view of a preform crystallization part forming system, FIG. 4 is an overall vertical cross-sectional view showing a heating device of the system, and FIG. 5 is an enlarged view of a main part of FIG.

In FIG. 3, 1 is a preform supply device, 2 is a heating device, 3 is a rotation chain, 4 is a transfer turret, and 5 is a transfer turret.
Is a preform molding device, and 6 is a carry-out device.

As shown in FIG. 3, the preform supply device 1 is composed of a shooter 110, a separation turret 120, a carry-in turret 130, and a charging turret 140, and is continuously connected from an injection molding machine (not shown) via the shooter 110. The sent high-temperature preform W is separated in the separation turret 120, and is transferred to a position (position C in FIG. 3) that intersects the turret 210 of the heating device 2 by the input turret 140 via the carry-in turret 130.

While the preform W is transferred by the input turret 140, the gate defect detector 141 inspects the quality of the gate, and if it is defective, the ejector 142 removes the preform W from the pocket 144 of the input turret 140. Further, when the thread-shaped resin scraps are projected beyond a certain amount, they are burned off by the heater rod 143. As a result, the preform W sent from the charging turret 140 to the heating device 2 has only a normal gate portion.

The preform W is fed into the pocket 223 of the sliding rod 221 from the pocket 144 of the charging turret 140 at the position C in FIG. 3 (see FIGS. 4 and 5). The preform W thus held in the pocket 223 is transferred in the direction of the arrow a by the rotation of the turret 210 of the heating device 2. When the sliding rod 221 reaches the position (a) in FIG. 3, the sliding rod 221 is guided by the cam groove 226 and descends to support the preform W held in the pocket 223 on the support 21.
It is inserted into the holder 216 provided on the No. 2. The preform W thus stored in the holder 216 is
It is held by the holder 216 and moves the same as the holder 216.

That is, the holder 216 revolves by the rotation of the turret 210, and at the same time, the preform W rotates in the direction of the arrow a as described above because the sprocket 218 fitted with the holder 216 and the chain 3 are spun to rotate. It revolves around the sun as it orbits.

On the other hand, the heater unit 230 heats the bottom portion of the preform W housed in the holder 216 via the through hole 217 having a perfect circle shape. At this time, since the preform W is rotating, the preform W receives the heat from the heater 233 while rotating, and the heating unevenness does not occur even when the heat generated from the heater is not uniform.

In this way, the preform W is heated at its bottom portion in a circular shape and uniformly between the portions shown in FIG. And
When it reaches the position of B in FIG. 3, the sliding rod 221 moves into the cam groove 22.
6 ascends and holds the preform W in the holder 216
Pull out from. Then, when the sliding rod 221 reaches the position D in FIG. 3, the preform W supported by the pocket 223 is transferred to the pocket 411 of the transfer turret 4,
As the transfer turret 4 rotates, it is sent to the preform molding apparatus 5 in the next step.

FIG. 6 is an overall longitudinal sectional view of the preform molding apparatus, FIG. 7 is an enlarged front view of a molding member in the apparatus, and FIG.
The figure is an enlarged cross-sectional view of a portion A in FIG.

In FIG. 6, reference numeral 510 denotes a rotary shaft, and an upper support 50 having both upper and lower ends fixed to a lower part 501 of the apparatus main body.
2 and a lower support 503 rotatably supported. A turret 511 is provided at the center of the rotary shaft 510.
Are provided, and a large number of pockets 512 for holding the preform W are provided on the outer peripheral edge thereof at appropriate intervals.

In addition, a lower guide body 520 is provided at a lower center of the rotary shaft 510.
Is fixedly provided, and a slide bearing 521 is provided on the outer peripheral edge of the lower guide body 520 in correspondence with the pocket 512. Elevating rods 522 are vertically movably supported on the slide bearings 521, and receiving members 523 are attached to the upper portions of the elevating rods 522.

The receiving member 523 is made of a heat insulating material such as engineering plastics such as nylon, polyimide, and Teflon (trade name), and has a recess 523a in which the bottom of the preform W is arranged. Since the receiving member 523 is formed of the heat insulating material as described above, the preform W can be supported without taking heat from the bottom of the preform W. Therefore, by absorbing heat from the bottom of the preform W by heat absorption, the preform is not rapidly cooled and the progress of crystallization of the bottom of the preform W is not hindered.

On the other hand, a cam roller 524 is provided below the elevating rod 522 so as to engage with a cam 525 provided on the apparatus body 501. The cam 525 is provided between the tees in FIG. 3, and gradually becomes high position between the tees, becomes the highest position between the tees, and gradually lowers between the tees. Has become. Therefore, between the torches, the receiving member 523 is in a state of supporting the bottom portion of the preform W from below.

In addition, the upper guide body 530 is provided at the upper center of the rotary shaft 510.
Is fixedly provided, and a slide bearing 531 is provided on the outer peripheral edge of the upper guide body 530 so as to correspond to the pocket 512. A molding rod 532 is vertically movably supported on each of the slide bearings 531. A molding member 533 for pressing the bottom portion of the preform W is attached to a lower portion of the molding rod 532.

A universal joint may be interposed between the forming rod 532 and the forming member 533, and in this case, the contact of the forming member 533 with the bottom of the preform can be made uniform.

The molding member 533 is made of a heat insulating material such as engineering plastics such as nylon, polyimide, Teflon (trade name), etc. With this, heat absorption from the preform W can be prevented during press molding, and the bottom of the preform W is crystallized. Does not inhibit the progression of. Also, the molding member 533
As shown in FIG. 7, a pressing projection 533a having a shape suitable for pressing is formed at the lower end of the. This pressing projection 5
33a presses the bottom center of the preform W,
The center of the lower end of the molding member 533 is formed as an apex.
Further, the side surface of the molding member 533 has a pressing projection 533a.
Serves as a guide portion 533b for pressing the center of the bottom portion of the preform W.

On the other hand, a cam roller 534 is provided on the upper part of the forming rod 532, and the cam roller 534 is mounted on the upper part 50 of the apparatus main body.
It is engaged with a cam groove 535 formed on the outer peripheral edge of the upper support 503 fixed to 2. The cam groove 535 gradually lowers between the heaths in FIG. 3, is at the lowest position between the torches, gradually increases between the heaths, and between the heaths. Is in the highest position.

Therefore, the molding member 533 is gradually inserted into the hollow portion of the preform W between the toes, and the molding member 533 cooperates with the receiving member 523 between the torch as shown in FIG. The protrusion 533a of the preform W is in a state of pressing the inner surface of the bottom portion of the preform W, and the molding member 533 is held between the teeth.
Is pulled out from the hollow part of the preform W,
Between F, the molded member 533 is completely extracted. The position (e) at which the preform W is supplied and the position (e) at which the preform W is discharged are completely provided between the leads from which the molding member 533 is extracted from the hollow portion of the preform W.

Next, an example of the preform crystallized portion molding method according to the first invention will be described. The method of this example is performed using the preform molding apparatus having the above-described configuration.

The preform W whose bottom is circularly and uniformly heated by the heating device 2 is transferred to the turret 5 in the preform molding device 5 at the position of E in FIG.
It is sent to 11 pockets 512. The preform W thus held in the pocket 512 is transferred in the direction of the arrow b by the rotation of the turret 511 accompanying the rotation of the rotary shaft 510.

When the receiving member 523 reaches the position shown in FIG.
25, it gradually rises and supports the bottom outer surface of the preform W held in the pocket 512 at the position of G. On the other hand, when the molding member 533 reaches the position shown in FIG. 3, it is guided by the cam 525 and gradually descends,
It enters into the hollow portion of the preform W held by the pocket 512 and presses the inner surface of the bottom portion of the preform W at the position of G.

Then, the preform W is supported by the receiving member 523 between the torches in FIG.
As shown in the figure, the inner surface of the bottom is pressed by the molding member 533. At this time, the bottom of the preform W that has been heat-treated by the heating device 2 is still in a semi-molten state. Therefore, the pressing projection 533a formed on the bottom surface of the molding member 533 is
Press the bottom inner surface of the preform W in the semi-molten state,
The bottom portion of the preform W has a receiving member 523 and a molding member 53.
It is compressed between 3 to form a concentric recess W ₁ .

In this way, the preform W is formed with the recess W _{1 on the} inner surface of the bottom between the torches shown in FIG. Further, it bubbles generated in the crystallization unit W _S by the heat treatment in the heating device 2,
It is discharged to the outside by pressing the molding member 533. Then, when it reaches the C position in FIG. 3, the receiving member 523 descends and the molding member 533 rises, and in the reposition in FIG. The molding member 533 is also pulled out from the hollow portion of the preform W. Next, when it reaches the position "n" in FIG. 3, the preform W supported by the pocket 512 is transferred to the carry-out device 6 and sent to the device of the next step.

The preform W sent out by the carry-out device 6 is crystallized while being naturally cooled, and a crystallization part is formed in the heat-treated part of the bottom part. A recess W ₁ is formed in the crystallized portion of the preform W.

The preform molded in this way can be reliably positioned by engaging the tip of the stretch rod with the recess formed in the bottom during stretch blow molding, and as a result, a high-quality stretch container can be produced with good yield. it can.

The above-described first invention method was described as an example in which after performing the heat treatment for crystallizing the preform, the preform was press-molded to form the recess before cooling and crystallizing. However, according to the preform molding method according to the embodiment of the second invention, the preform whose bottom is once crystallized is heated to near the melting point again to soften the crystallized part, and then pressure-molded by the molding member. You may do it. In this case, the preform molding apparatus of the present invention can be used separately from the above-mentioned preform crystallization system.

Next, examples of the preform crystallized portion forming method of the third invention will be described.

The preform W supplied to the preform supply device 1 shown in FIG. 3 is molded by injecting the molten resin P into an injection molding die.

Therefore, in this injection molding stage, the method of the present embodiment is designed to form a recess in the bottom of the preform. That is, as shown in FIG. 9, injection molding is performed using a mold 702 in which a convex portion 701 is provided in a portion forming the inner bottom portion of the preform. In this way, the inner bottom portion of the molded preform W, the recess W _S is formed by the convex portion 701 of the mold 702.

Next, this preform W is supplied to the preform supply device 1 shown in FIG. 3, the bottom portion having the concave portion is heated by the heating device 2, and then crystallization is promoted by cooling to form a concave crystallization in the bottom portion. To form a part.

FIG. 10 is a vertical sectional view showing another embodiment of the preform.

The preform W shown in the figure has a recessed portion W ₁ for positioning a stretch rod at the center of the bottom, and at the time of stretch blow molding, by engaging the tip of the stretch rod 601 with this recessed portion W ₁ , centering is achieved. You can do it. Further, on the outside of the concave portion W _1, on the boundary between the portion W _P which are stretched by stretch blow molding and crystallization unit W _S, it is formed a recess W ₂ ring. This recess W ₂ makes the boundary thin, and enables smooth and uniform stretch blow molding from the boundary to the outside.

In order to form such recesses W ₁ and W ₂ on the bottom of the preform W, a molding member 833 having pressing protrusions 833a and 833b as shown in FIGS. 11 (a) and 11 (b) can be used. Good. The pressing projection 833a is formed at the center of the lower end of the molding member 833, and includes a heat-treated portion (that is, a portion that is crystallized as cooling proceeds thereafter) in the bottom portion of the preform W and a non-heat-treated portion. Press the boundary line of.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist.

For example, the planar shape of the concave portion of the preform molded according to the present invention is not limited to a circular shape, and various shapes such as a star shape and a square shape can be used.

[Effects of the Invention] As described above, according to the preform molding method and the apparatus thereof of the present invention, it is possible to easily mold the crystallized portion of the preform crystallized in the state where the concave portion is formed.

[Brief description of drawings]

The drawings are for explaining the embodiments of the present invention. FIG. 1 is a vertical sectional view of a preform, FIG. 2 is a vertical sectional view showing the outline of stretch blow molding, and FIG. 3 is a preform crystallizing part. Fig. 4 is an overall schematic view of the molding system, Fig. 4 is an overall longitudinal sectional view showing a heating device of the system, and Fig. 5 is an enlarged view of a main part of Fig. 4.
FIG. 6 is an overall vertical sectional view of the preform crystallizing section forming apparatus, FIG. 7 is an enlarged front view showing a forming member in the apparatus, and FIG. 8 is an enlarged sectional view of part A in FIG. FIG. 10 is a vertical cross-sectional view showing a preform injection molding apparatus.
FIG. 11 is a longitudinal sectional view showing a modified example of the preform, FIG. 11 (a) is a front view of a molding member for press-molding the bottom of the preform shown in FIG. 10, and FIG. 11 (b) is a bottom view of the same. . 510: rotating shaft, 511: turret 512: pocket, 523: receiving member 524: cam roller, 525: cam 532: forming rod, 533: forming member 534: cam roller, 535: cam groove W: preform, W ₁ : recess

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Claims (4)

[Claims] 1. A tubular preform with a bottom is formed by injection molding, and then the bottom of this preform is heat treated to be melted, and the inner bottom of the preform in a molten or semi-molten state is molded into a molding member. A method for forming a crystallized portion of a preform, characterized in that a concave portion is formed in the inner bottom portion by pressing with, and then the preform bottom portion is cooled and crystallized. 2. A bottomed tubular preform is formed by injection molding, the bottom of this preform is heat treated and then cooled to crystallize, and then the bottom of this preform is heat treated again. It is characterized in that the inner bottom portion of the preform in a molten or molten or semi-molten state is pressed by a molding member to form a recess in the inner bottom portion, and then the preform bottom portion is cooled and recrystallized. Method for forming crystallization part of preform. 3. A mold having a convex portion formed on a portion forming an inner bottom portion of the preform is manufactured, and a molten polyester resin is injected and injected into the mold to form a preform having a concave portion at the bottom. A method for forming a crystallized portion of a preform, characterized in that the bottom portion of the preform is heat-treated, and then the bottom portion of the preform is cooled to be crystallized. 4. A preform molding means for molding a tubular preform with a bottom, a transfer means for transferring the preform taken out from the preform molding means, and a bottom portion of the preform transferred by the transfer means. And a receiving member that supports the outer surface of the bottom of the preform in a molten or semi-molten state, which is heated by the heating means, and is disposed so as to face the receiving member and is used to form a recess at the tip. A preform crystallization part forming device comprising: a forming member having a projection; and a driving unit that cooperates with the receiving member and the forming member to form a recess in the bottom of the preform.