JP2011105019A - Method for manufacturing plastic product and apparatus of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a plastic product capable of coping with various product shapes while suppressing the equipment cost. <P>SOLUTION: A parison 30 is molded in such a state as to integrate with a mouth ring holder 28 by injecting a molten thermoplastic resin into an injection mold 12 in which the mouth ring holder 28 is attached, then, before the parison 30 is hardened, the parison 30 and the mouth ring holder 28 are separated from the injection mold 12, and the parison 30 is conveyed from the injection mold 12 to a blow mold 52 by holding the mouth ring holder 28 out of these two, and further, while holding the parison 30 inserted in the blow mold 52 by fixing the mouth ring holder 28 to the inlet part of the blow mold 52 and also keeping the parison 30 hermetically closed, a product 100 having a shape corresponding to a molding space 58 is formed by introducing blow air A into the parison 30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for manufacturing a hollow plastic product by using both injection molding and blow molding.

The injection blow molding method, which is widely used as a molding method for thermoplastic products, is that a parison, which is a bottomed cylindrical preform, is molded by injection molding, and then air is blown into the parison by blow molding. Is a method of forming a product of a predetermined shape by expanding and deforming the parison (see Non-Patent Documents 1 to 3, for example). This injection blow molding method can be further classified into the following two types.
(A) A parison molded by injection molding is once cooled and solidified, and then reheated and blow-molded in a separate step. (B) The parison molded by injection molding is kept at a high temperature, for example, 120 This is a one-stage type injection blow in which the male mold is transferred to the blow mold using a three-station machine that is index rotated by several degrees, and then blow molding is performed. These processes are performed in the same equipment.

Nakatsuji Sumi, “Plastic Textbook for Engineers”, Industrial Research Committee, issued December 1, 1997 Shinichi Matsuoka “Plastic Molding” Corona, May 2002 Ken Ibouchi and Tomohiro Kuramochi “Introduction to Plastics” Industrial Research Committee, issued April 1, 1999

  However, the above-mentioned two-stage type injection blow requires a reheating process, which increases the equipment cost, and also requires time for cooling and solidifying the parison after injection molding. There was a problem of becoming.

  In addition, although the reheating process is not necessary in the one-stage type injection blow, there is a problem that the equipment cost is increased and the production machine is not suitable for small-scale production because the molding machine is increased in size and dedicated. Further, since a space for rotating the index together with the male mold is required, it is only suitable for manufacturing a relatively small product, and there is a problem that the product shape is not flexible.

  In view of the problems of the conventional methods as described above, an object of the present invention is to provide a method for producing a plastic product that can cope with a wide range of product shapes while suppressing equipment costs.

  In order to solve the above-mentioned problems, the present invention provides a plastic product manufacturing method for continuously molding an injection-molded parison into a predetermined product shape by blow molding, and uses an injection molding machine including an injection mold to hold a holder in advance. An injection process for molding the parison in such a state that the holder is integrally attached to one end thereof by injecting a molten thermoplastic resin into the injection mold in a state where the mold is mounted, and a molded parison A transfer step of transferring the parison from the injection molding machine by holding the holder out of the injection mold and a blow mold having a molding space inside. And the injection Using a blow molding machine independent of the molding machine, the transported parison is held in an inserted state inside the blow mold by fixing the holder to the inlet of the blow mold, and the parison is further predetermined. A blow step of forming a product having a shape corresponding to the molding space by introducing blow air into the parison in a state of being sealed by the sealing means, and the injection mold is a male mold having a convex portion And a female die having a concave portion corresponding to the convex portion, and forming a cavity space corresponding to the shape of the parison between the male die and the female die, and introducing molten resin into the cavity space The resin inflow passages are provided on both sides of the male mold and the female mold, and the injection step includes two resin inflow paths provided in the injection mold. While state where the resin inlet path and obstruction of the out, is characterized in that a step of molding the said parison by injecting molten resin into the cavity space through the other resin inlet passage.

  According to this manufacturing method, by injecting a molten thermoplastic resin into an injection mold in a state in which the holder is mounted in advance, the parison is molded in a state of being integrated with the holder. It is configured to transfer the parison from the injection type to the blow type by holding, so that the injection process is completed before the parison is cured, and the parison before curing can be easily and quickly transferred to the blow type. As a result, blow molding can be performed directly without reheating the parison. Therefore, it is possible to reduce the equipment cost as compared with the conventional two-stage type injection blow in which it is necessary to reheat the parison before blow molding.

  On the other hand, unlike the conventional one-stage type injection blow, it is not necessary to perform the injection process and the blow process in the same machine, so that the injection molding machine and the blow molding machine can be configured with independent equipment. A general-purpose molding machine can be used for both facilities. Therefore, it is possible to reduce the equipment cost even when compared with a one-stage type injection blower in which the equipment is inevitably enlarged by incorporating these equipment into the same machine. In addition, since the injection molding machine and blow molding machine are independent, products of various shapes can be obtained by replacing only the blow mold without changing the shape of the injection mold (parison), so the equipment is dedicated. Therefore, it is possible to cope with a wide range of product shapes at a low cost compared to the conventional one-stage type injection blow that requires modification or replacement of the entire equipment when changing the product shape.

  Here, if the resin inflow path for introducing the molten resin into the injection mold (cavity space) is provided inside the injection mold male mold, the gate mark does not remain on the outer surface side of the product ( Since the gate portion is formed on the inner surface side of the parison), it is desirable for finishing the product with a good appearance. However, depending on the shape of the parison, the resin inflow path is arranged on the injection-type female mold side so that the gate part is formed on the outer surface side of the parison. In some cases, it can be made difficult to occur, and this is often found only after actual molding.

  Therefore, in the present invention, the injection mold is provided with the resin inflow path on both sides of the male mold and the female mold, and one of the two resin inflow paths is closed. In this state, the molten resin is injected into the cavity space through the other resin inflow passage. This is very convenient because either one of the two resin inflow passages can be selectively used.

  The injection step is to form a cylindrical parison having an opening at one end and a bottom at the other end as the parison, and as a holder when integrating with one end of the parison. It may be a step of using a mouth holder having a through hole so as not to close the opening at one end of the parison. In this case, the sealing means for sealing the parison in the blowing step can be realized by closing the through hole of the mouth holder attached to one end of the parison while securing the blow air introduction path. .

  In this case, in the blowing step, there is a case where it is desired to mold a relatively deep bottom product by largely deforming the bottom portion of the other end of the parison in the axial direction. However, when the axial dimensional difference between the parison and the product is large as described above, it is difficult to reliably mold the product simply by blowing air into the parison. Therefore, in such a case, the blowing step can be performed before or during the introduction of the blow air by using an extension rod that can be inserted through the through hole of the mouth holder and press the bottom of the parison from the inner surface side. The parison is preferably used by stretching and deforming the parison in the axial direction. Thereby, even when the axial dimensional difference between the parison and the product is large, the product can be reliably molded.

  In this case, if the stretch rod is provided with a hollow portion through which air passes and an air blowing hole that opens to the surface through the hollow portion, the blowing step uses the stretch rod to form the air. It can be performed by introducing blow air blown out from the blow hole into the inside of the parison. That is, since the extending rod also serves as a blow pipe for introducing air into the parison, the structure of the blow molding machine is simplified.

  On the other hand, the injection step forms a cylindrical parison having openings on both sides of the one end and the other end as the parison and, when the holder is integrated with one end of the parison, It is good also as the process of using the mouth-shaped holder which has a through-hole for not closing the opening part of one end of this. In this case, the sealing means for sealing the parison in the blowing step closes the through hole of the mouth holder attached to one end of the parison while securing the blow air introduction path, and the other end of the parison. Can be achieved by contacting the bottom of the blow mold with the bottom.

  Thus, the other end of the parison that contacts the bottom surface inside the blow mold needs to be stably held and sealed during blow molding. For this reason, the blow mold is in close contact with the bottom surface having a projecting portion that can be fitted into the opening of the other end of the parison in contact with the other end of the parison and the outer periphery of the other end of the parison. It is preferable to use a blow mold that includes a peripheral surface having a circumferential protrusion that can bite into the parison. This makes it possible to perform blow molding in a stable state while fixing the other end of the parison in both the radial direction and the axial direction.

  About the said holder, when it is necessary to remove this from a product after shaping | molding of a product, it is preferable to use the holder which can be divided | segmented as a holder and to embed a magnet in the division | segmentation surface. Thereby, the operation of removing the holder from the product can be easily performed by dividing the holder, and the holder once divided can be easily re-coupled.

  On the other hand, depending on the product, there may be a case where a member designed to constitute a part of the product is to be integrally attached to one end of the product. In such a case, the design member may be used as the holder. Thereby, it is not necessary to attach this in a later process, and the production efficiency can be improved.

  In addition, there may be a case in which a different design member is to be integrally attached to the outer surface of the product. In this case, it is good to perform the said blow process in the state which inserted the said design member in the inner surface of the said blow mold previously.

  In the manufacturing method as described above, it is preferable that the injection process for forming a new parison is performed in parallel while the blow process is performed. That is, while the parison is formed by the injection process and the blow process is performed on the parison, the injection process for forming a new parison is started immediately and this is repeated thereafter. In this way, since the injection process and the blow process are continuously performed in parallel, the molding cycle time of the product can be greatly shortened.

  As described above, according to the method for producing a plastic product of the present invention, it is possible to cope with a wide range of product shapes while suppressing facility costs.

(Embodiment 1)
The plastic product manufacturing method according to this embodiment includes the following steps.

1) Injection process This process is a process of forming the parison 30 which is a cylindrical preform using the injection molding machine 10 shown in FIG. Specifically, the step of molding the parison 30 in a state of being integrated with the mouthpiece holder 28 by injecting a molten thermoplastic resin into the injection mold 12 in a state in which the mouthpiece holder 28 is previously attached. It is.

  The parison 30 has a cylindrical shape having an opening 30a at one end and a bottom 30b at the other end, as shown in FIG. The mouth holder 28 is integrally attached to one end of the parison 30. In the present specification, the term “cylindrical” is a concept including a container having a shallow bottom such as a parison 530 (FIG. 12A) according to a modified example described later.

  The mouth holder 28 is a ring-shaped member having a through hole 28 a that is substantially the same shape as the opening 30 a of the parison 30, and has a shape that surrounds the outer periphery of one end of the parison 30. Since a female screw 29 is provided on the inner peripheral surface of the mouth holder 28, a screw portion is formed on the outer periphery of one end of the parison 30 correspondingly. If such a screw portion is not required, the female screw 29 may be omitted.

  Further, the mouth holder 28 has a divided structure composed of component parts 281 and 282, as shown in FIG. This is to make it possible to easily remove the mouth holder 28 from the product 100 (FIG. 3C) obtained by the blow process described later by dividing the mouth holder 28. Further, a magnet 40 is embedded in each divided surface of the component parts 281 and 282 of the mouth holder 28. Thereby, the mouth holder 28 once divided can be easily combined and reused.

  Returning to FIG. 1 again, the injection mold 12 has a structure in which a male mold 14 and a female mold 16 face each other, and a parison 30 can be molded therein.

  The male mold 14 is composed of a male frame mold 17 and a male core mold 18, and the female mold 16 is similarly composed of a female frame mold 19 and a female core mold 20. The male frame mold 17 and the female frame mold 19 are configured by combining a plurality of template plates (17a to 17d and 19a to 19c). The male core mold 18 and the female core mold 20 are fixed to the innermost mold plates (17a and 19a) of the male frame mold 17 and the female frame mold 19 with, for example, bolts or the like.

  The male core mold 18 has a convex portion 18a (FIG. 2), and the female core mold 20 has a concave portion 20a (FIG. 2) corresponding to the convex portion 18a, in order to mold the parison 30 therebetween. The cavity space 22 (a space corresponding to a molded product) is formed. According to this configuration, when it is desired to change the shape of the parison 30, it is possible to cope with it by replacing only the male core mold 18 and the female core mold 20 (the injection mold 12 as a whole need not be replaced). If not particularly necessary, the male core mold 18 and the female core mold 20 may be integrated with the male frame mold 17 and the female frame mold 19, respectively.

  A mouth holder 28 can be attached to the root portion of the male core mold 18. A magnet 40 is embedded in each mating surface of the male core mold 18 and the mouth mold holder 28. Accordingly, the mouth holder 28 is detachably fixed to the male core mold 18. When the mouth holder 28 is detachably fixed with a certain amount of fitting force, for example, the magnet 40 may be omitted.

  The male mold 14 is provided with an ejector pin 24 that abuts against the mouth holder 28 (in a state of passing through the mold plates 17a and 17b and the male core mold 18). The ejector pin 24 is configured to be able to protrude in the direction in which the mouth holder 28 is pushed out. When the injection die 12 is opened, the ejector pin 24 forces the mouth holder 28 to be pushed out. (FIG. 2). Thereby, even if the mouth holder 28 and the male core mold 18 are coupled by the magnet 40, the mouth holder 28 can be easily detached from the male core mold 18.

  Further, a nozzle 26 which is an injection portion of a screw (not shown) for melting (plasticizing) and injecting a raw material resin is connected to the male mold 14 (template plate 17d). It flows into the male mold 14 from the nozzle 26. In order to introduce the molten resin that has flowed into the cavity space 22, a resin inflow path 32 is provided inside the male mold 14.

  In this resin inflow path 32, since resin remains excessively at the time of molding of the parison 30, a gate portion 34 (an inlet portion of a molded product) is formed in that portion. In this embodiment, the resin inflow path 32 is a cavity. Since the connection portion (pin gate portion 34a) with the space 22 is squeezed into a small hole shape, when the injection die 12 is opened and the parison 30 is taken out, the parison 30 is the gate portion at the portion of the pin gate portion 34a. 34 and divided. As a result, only a few gate traces remain in the parison 30. In addition, in this embodiment, since the molten resin is caused to flow from the male mold 14 side, the gate trace remains on the inner surface side of the parison 30. Therefore, no gate marks remain on the outer surface side of the product 100 (FIG. 3), and the appearance is better.

  However, depending on the shape of the parison 30, when the molten resin is caused to flow from the female mold 16 side (the gate portion 34 is formed on the outer surface side of the parison 30), molding defects due to retention of the molten resin or the like occurs. This can often be difficult, and this is often found only after actual molding. Therefore, in this embodiment, the resin inflow passage 36 is provided on the female die 16 side as well as the male die 14. Thereby, the resin inflow path 32 on the male mold 14 side and the resin inflow path 36 on the female mold 16 side can be selectively used. When it is preferable to allow the molten resin to flow from the female mold 16 side, the resin inflow path 36 on the female mold 16 side may be used by connecting the nozzle 26 to the female mold 16. However, since the resin inflow path 36 on the female mold 16 side is not used in this embodiment, the resin inflow path 36 is sealed by plugging the tip thereof.

  The procedure for molding the parison 30 using the injection molding machine 10 as described above is as follows. First, the mouth holder 28 is attached to the inside of the injection mold 12 (the root portion of the male core mold 18). The injection mold 12 is clamped. Next, the raw material resin is melted (plasticized) with an unillustrated screw, and the molten resin is injected into the injection mold 12 from the nozzle 26. Then, molten resin is filled into the cavity space 22 through the resin inflow path 32, and the parison 30 is molded. At this time, since one end of the parison 30 is molded so as to be in close contact with the inner peripheral portion of the mouth mold holder 28 previously mounted in the injection mold 12, the parison 30 has the mouth holder at the one end. It is molded in a state where it is integrated with 28.

2) Transfer process This process is a process in which the parison 30 molded in the injection process is detached from the injection mold 12 and transferred to the blow molding machine 50 (FIG. 3) before it is cured.

  First, as shown in FIG. 2, before the parison 30 is cured, the injection mold 12 is opened. At this time, since the parison 30 remains on the male mold 14 (male core mold 18) side together with the mouth holder 28, the ejector pin 24 is protruded from the male mold 14 so as to be removed. As a result, the mouth holder 28 is forcibly pushed out and separated from the male die 14, and the parison 30 integrated with the mouth holder 28 is also removed. At this time, the gate portion 34 remaining in the male mold 14 can be automatically dropped by dividing the male mold frame 17 composed of a plurality of mold plates (17a to 17d) by an appropriate dividing surface. . Even when the molten resin is caused to flow from the female mold 16 side (when the resin inflow passage 36 is used), the female mold 19 can be divided in the same manner to drop off.

  Next, before the parison 30 is cured, by holding the detached mouth holder 28 and the mouth holder 28 of the parison 30, they are transferred to the blow molding machine 50 (FIG. 3). The reason why the transfer is performed by holding the mouth holder 28 is that the parison 30 is not yet cured and cannot be directly held. Therefore, the transfer is always performed by holding the mouth holder 28. The transfer may be performed by a machine or by a person. When a person transports, for example, if a lightweight aluminum alloy is used as the material of the mouth holder 28, the burden associated with the transport can be reduced.

3) Blow process This process is a process of obtaining the product 100 by performing blow molding using the blow molding machine 50 shown in FIG. 3 with respect to the parison 30 transferred by the said transfer process.

  The blow mold 52 of the blow molding machine 50 includes a slide mold 54 configured to be slidable and slidable to the left and right, and a floor mold 56 fixed to the bottom, and a molding space 58 corresponding to the shape of the product 100 is formed therein. Have. Further, the upper portion of the slide die 54 (the entrance portion of the molding space 58) has a recess for sandwiching and fixing the mouth holder 28. Thereby, the parison 30 can be held in a stable state in the molding space 58.

  Further, the blow molding machine 50 has a press lid 60 that can seal the parison 30 by closing the mouth holder 28, and passes through the press lid 60 and passes through the through hole 28 a of the mouth holder 28. And a blow pipe 62 through which blow air A can be introduced.

  The procedure for performing blow molding using the blow molding machine 50 as described above is as follows. First, as shown in FIG. 3A, the mouth mold holder 28 is fixed to the upper part of the slide mold 54 of the blow mold 52, thereby parison. 30 is held in the molding space 58 in an inserted state. Then, the parison 30 is sealed with the presser lid 60, and the blow air A is introduced into the parison 30 from the blow pipe 62 in this state.

  Then, as shown in FIG.3 (b), the parison 30 which has not yet hardened expand | swells and deform | transforms with the blow air A blown in inside. In this way, a product 100 having a shape corresponding to the molding space 58 is obtained. When the resin is solidified, as shown in FIG. 3C, the slide mold 54 is opened and the product 100 is taken out, and the mouth holder 28 is divided and removed from the product 100.

  In the manufacturing method as described above, since the injection-molded parison 30 is directly blow-molded without reheating, it is necessary to reliably transfer the parison 30 to the blow-molding machine 50 before the parison 30 is cured. There is. For this reason, it is important to appropriately manage the time of each process. This time should be appropriately set according to the resin material, weight, etc., and an example thereof will be shown below.

<Example 1>
a) Molded product Material ... Acrylic Weight ... 200g
Average wall thickness: about 5mm
b) Molding conditions (injection process)
Injection temperature: 240 ± 10 ° C
Time to complete injection: about 10 seconds (5 seconds for injection, 5 seconds for holding pressure)
Cooling time after completion of injection ... 5-7 seconds Resin surface temperature when mold is opened ... 150-170 ° C
(Transfer process)
Resin surface temperature when taking out the parison ... 140-150 ° C
Transfer time from injection molding machine to blow molding machine… 5-7 seconds (blowing process)
Resin surface temperature at the start of blow ... 130-140 ° C
Blow time ... 5-10 seconds Resin surface temperature after completion of blow ... 80-90 ° C
As a result of molding under such conditions, the injection-molded parison 30 can be transferred to the blow molding machine 50 before it is cured, and blow molding can be performed, and a good product 100 can be obtained. .

  Here, the molding cycle time required for molding per product when the product 100 is continuously produced will be considered. First, when each process is sequentially performed one by one, this time is naturally equal to the sum of the time required for each process. On the other hand, while the parison 30 is molded by the injection process and the blow process is performed on the parison 30, the injection process for molding a new parison 30 is started immediately and this is repeated thereafter. For example, the molding cycle time is greatly reduced. In other words, by continuously performing the injection process and the blow process in parallel, this molding cycle time can be set to either one of the injection process or the blow process (more precisely, the process that requires more time). It will take less time. For this purpose, it is necessary to prepare a plurality of mouth holders 28.

  Specifically, based on Example 1 above, when each process is performed one by one in sequence, the molding cycle time includes the time for mounting the mouth mold holder 28 and the time for taking out the product 100 in addition to the above time. It will be about 30 to 40 seconds. On the other hand, if the injection process and the blow process are performed in parallel, the time required for the injection process alone is about 20 seconds.

  As described above, according to the manufacturing method of the present embodiment, the parison 30 is injection-molded in a state of being integrated with the mouth holder 28, and then the mouth holder 28 is held, Since the parison 30 in a state before being cured is transferred from the injection molding machine 10 to the blow molding machine 50, it is possible to perform blow molding directly without reheating the parison 30. Therefore, it is possible to reduce the equipment cost as compared with the conventional two-stage type injection blow in which it is necessary to reheat the parison 30 before blow molding.

  On the other hand, unlike the conventional one-stage type injection blow, it is not necessary to perform the injection process and the blow process in the same machine, so the injection molding machine 10 and the blow molding machine 50 can be configured with independent facilities, As a result, general-purpose molding machines can be used for both facilities. Therefore, it is possible to reduce the equipment cost even when compared with a one-stage type injection blower in which the equipment is inevitably enlarged by incorporating these equipment into the same machine. In addition, since the injection molding machine 10 and the blow molding machine 50 are independent, the product 100 having various shapes can be obtained by replacing only the blow mold 52 without changing the shape of the injection mold 12 (parison 30). However, when the shape and size of the product 100 changes drastically, it is also necessary to change the injection mold 12, but even in this case, it is possible to manufacture a wide variety of products 100 while reducing the types of the injection mold 12. it can. On the other hand, in the case of the conventional one-stage type injection blow, since the equipment is dedicated, if the shape of the product 100 is changed, it is necessary to modify or replace the entire equipment. The method can accommodate a wide variety of product 100 shapes at a lower cost. Furthermore, the fact that general-purpose molding machines can be used as the injection molding machine 10 and the blow molding machine 50 has an advantageous effect on manufacturing efficiency. That is, in the case of the conventional one-stage type injection blow, the molding cycle time of the product 100 is inevitably increased due to the increase in size and complexity of the machine, but in the case of the manufacturing method of the present embodiment, There is nothing. Specifically, the molding cycle time by the conventional one-stage type injection blow is generally about 60 seconds, but according to the manufacturing method of the present embodiment, as in the case of Example 1 above, It takes about 20 seconds.

  In the present embodiment, the mouth holder 28 is configured to be separable so that it can be easily detached from the molded product 100. However, depending on the situation, it may be an integral structure (not separable). For example, when the product 200 having a shape as shown in FIG. 5A is molded, the mouth holder 128 cannot be divided because it is obstructed by the product 200 existing so as to surround it. There is no problem with the structure. In this case, the operation of removing the mouth holder 128 from the product 200 may be performed by rotating the mouth holder 128.

  Further, the mouth holder 28 is not limited to the shape surrounding the outer periphery of one end of the parison 30 as in the present embodiment. For example, the mouth holder 28 is similar to the mouth holder 228 shown in FIG. It is good also as a shape which follows the inner periphery of one end. In this case, if the female screw 229 is formed on the outer peripheral surface of the mouth holder 228, a screw portion can be formed on the inner peripheral surface of one end of the parison 130 correspondingly.

  Further, when the design member 70 designed to constitute a part of the product is attached to one end thereof and used in that state as in the product 300 shown in FIG. 5C, the injection process. In this case, the design member 70 may be used as the mouth holder 328. In this way, it is not necessary to attach the design member 70 in a later process, and manufacturing efficiency can be improved.

  In addition, as the injection mold 12 of the present embodiment, either a horizontal type (with the axis oriented horizontally) or a vertical type (with the axis oriented vertically) can be used. Is preferably used. The first reason is that since the parison 30 is taken out from the injection mold 12 in a state before being cured, when the horizontal mold is used as the injection mold 12, the parison 30 is in a horizontal posture (the axis of the parison 30 is This is because the parison 30 is likely to be deformed because the parison 30 is taken out from the injection mold 12 in a horizontal orientation. The second reason is that the blow mold 52 is generally a vertical type (the axis of the blow mold 52 is vertically oriented), so if the injection mold 12 is a horizontal type, the parison 30 is transferred to the blow mold 52. This is because it is necessary to set the blow mold 52 after rotating the parison 30 by 90 degrees, which is not preferable in terms of work efficiency.

  The blow process of the present embodiment is performed using a blow molding machine 50 configured to blow blow air A into the parison 30, and this is performed from the inner peripheral surface of the blow mold 52 to the inside of the molding space 58. You may carry out using what is called a vacuum forming machine which expands and deforms the parison 30 by attracting | sucking the air (outside of the parison 30).

  In addition, the blowing step can be performed in a state where a design member 170 designed to constitute a part of the product as shown in FIG. 6A is previously attached to the inner surface of the blow mold. If it does in this way, as shown in FIG.6 (b), the product 400 by which this design member 170 was integrally attached to the outer surface can be shape | molded.

(Embodiment 2)
In the first embodiment, in the injection process, the injection molding machine 10 (pin-gate type) that leaves only a minimum gate mark in the parison 30 is used, but a basic molding machine is used as the injection molding machine 10. In this case, as shown in FIG. 7, the directly-connected gate part 134 remains on the outer surface side of the parison 230 (direct gate system). In this case, before the parison 230 is transferred to the blow molding machine 50, the gate part 134 may be cut and the blowing process may be performed in that state. It becomes difficult to transport to

  Therefore, in this embodiment, by using the blow molding machine 150 shown in FIG. 8, it is possible to perform blow molding on the parison 230 in a state where the gate part 134 remains. That is, the bottom hole 156a is provided in the bottom mold 156 of the blow mold 152 so that the gate portion 134 is inserted into the bottom hole 156a, whereby the parison 230 is expanded and deformed (FIG. 8B). ) So that the gate part 134 does not get in the way. In addition, according to this configuration, when the parison 230 is set in the blow mold 152, the bottom hole 156a positions the parison 230 by guiding the gate portion 134. Therefore, the posture of the parison 230 is stabilized during blow molding. Can be made. For this reason, it becomes possible to make it difficult to produce defects, such as uneven thickness at the time of blow molding. In this case, the gate part 134 may be cut after blow molding.

(Embodiment 3)
In this embodiment, as shown to Fig.10 (a), the some parison 330 is shape | molded by one injection process. Specifically, instead of the male core mold 18 and the female core mold 20 in the injection mold 12 used in the first embodiment, a male core mold 118 having a plurality of convex portions 118a as shown in FIG. Correspondingly, the injection process is performed using an injection mold (not shown) including a female core mold 120 having a plurality of recesses 120a. In this case, the male core mold 118 is provided with a mouth holder 428 having a plurality of through holes 428 a as shown in FIG. 10A in advance, so that the mouth holder 428 is attached to each parison 330. So that it can be attached to one end of the unit.

  Then, by performing a blowing process using a blow mold (not shown) having a plurality of molding spaces, blow molding is simultaneously performed on each parison 330. As a result, a plurality of products 500 as shown in FIG. 10B can be obtained at the same time, and the production efficiency can be greatly increased. As the product 500, a relatively small product that is produced in large quantities is suitable.

(Embodiment 4)
In this embodiment, a parison having an opening 430a at one end (the side on which the mouth holder 28 is attached) and an opening 430b at the other end as shown in FIG. 430 is molded, and blow molding is performed on the parison 430 by using a blow molding machine 250 shown in FIGS.

  FIG. 11A shows a state before the parison 430 is set on the blow mold 252, FIG. 11B shows a state after the setting, and FIG. 11C shows the state shown in FIG. FIG. As shown in FIGS. 11A to 11C, the blow mold 252 includes a slide mold 254 and a floor mold 256 as in the blow molding machine 50 of the first embodiment. However, as a configuration different from that of the first embodiment, the slide mold 254 has a circumferential surface 254a that is in close contact with the outer circumference of the other end of the parison 430 when the parison 430 is set in the blow mold 252. On the circumferential surface 254a, a circumferential protrusion 254b that bites into the parison 430 is provided. In addition, the floor mold 256 has a bottom surface 256a that makes contact with the other end of the parison 430 in the same state, and a protrusion that can be inserted into the opening 430b at the other end of the parison 430 on the bottom surface 256a. It has an installation part 256b. The other configuration of the blow molding machine 250 is the same as that of the first embodiment.

  In order to perform blow molding using such a blow molding machine 250, first, as shown in FIG. 11A, the parison 430 is inserted into the blow mold 252 with the slide mold 254 opened left and right.

  Then, as shown in FIG. 11 (b), the other end of the parison 430 is brought into contact with the bottom surface 256 a of the floor mold 256 and the slide mold 254 is closed to fix the mouth holder 28 to the upper part of the slide mold 254. Thus, the parison 430 is set on the blow mold 252. Then, as shown in FIG. 11C, the circumferential surface 254 a of the slide mold 254 is in close contact with the outer periphery of the other end of the parison 430, and the protrusion 254 b bites into the parison 430. Further, a protruding portion 256 b protruding from the bottom surface 256 a of the floor mold 256 is fitted into the opening 430 b of the parison 430. In this way, the other end of the parison 430 is constrained / fixed and closed in both the radial direction and the axial direction. Note that one end of the parison 430 is closed by a presser lid 60 as shown in FIG. Thus, the parison 430 is completely sealed.

  Next, blow air A is introduced into the parison 430 from the blow pipe 62 in this state, and the parison 430 is expanded and deformed. At this time, since the other end of the parison 430 is completely fixed as described above, the other end of the parison 430 escapes along with the expansion and deformation (being pulled by the central portion of the parison 430 that undergoes expansion and deformation, This other end does not move upward), and the sealed state of the parison 430 is stably maintained.

  Thus, according to the manufacturing method of this embodiment, blow molding can be performed in a stable state on the parison 430 having the openings (430a, 430b) at both ends.

(Embodiment 5)
In this embodiment, the relatively shallow bottom parison 530 shown in FIG. 12A is formed by the injection process, and the blow molding machine 350 shown in FIGS. 12A to 12C is formed on the parison 530. Blow molding is performed using As a result, a relatively deep bottom product 600 shown in FIG.

  The blow molding machine 350 includes a stretching rod 64 as a different configuration from the blow molding machine 50 of the first embodiment. The extending rod 64 includes a hollow portion 64a through which blow air A passes and an air blowing hole 64b that opens to the surface through the hollow portion 64a and presses the bottom portion 530b of the parison 530 during blow molding. Yes. The other structure is the same as that of the blow molding machine 50 in the first embodiment.

  In order to perform blow molding using such a blow molding machine 350, first, the parison 530 is set in the blow mold 352 as shown in FIG. Then, the presser lid 60 and the extending rod 64 are brought close to the blow mold 352 as shown in the figure. Then, as shown in FIG. 12 (b), the tip of the extending rod 64 presses the bottom portion 530 b of the parison 530 from the inner surface to stretch and deform the parison 530 in the axial direction, and the presser lid 60 closes the mouth holder 28. . And in this state, as shown in FIG.12 (c), the blown air A introduce | transduced into the hollow part 64a of the extending | stretching rod 64 is blown off from the air blowing hole 64b, the parison 530 is expanded and deformed, and the product 600 is obtained.

  According to the manufacturing method of the present embodiment as described above, by pressing the bottom portion 530b of the parison 530 using the stretching rod 64, blow molding is performed while the parison 530 is stretched and deformed in the axial direction. Even when the axial dimensional difference with the product 600 is large, the product 600 can be reliably molded.

  In the present embodiment, after the parison 530 is stretched and deformed by the stretching rod 64, the blow air A is blown out from the air blowing holes 64b of the stretching rod 64. However, these may be performed in parallel. Further, the extending rod 64 may be a simple rod-like body (the blow air A blowing mechanism in the extending rod 64 is omitted), and instead, a blow pipe (not shown) separate from the extending rod 64 may be separately prepared. .

(Embodiment 6)
In the first embodiment, the cross-sectional shapes of the parison 30 and the product 100 are not particularly limited, and can be set to various shapes such as a circle and a polygon (the same applies to other embodiments). However, from the viewpoint of forming the product 100 having a uniform thickness, it is preferable that the cross-sectional shape is the same as that of the product 100 at the time of the parison 30 (for example, the cross-sectional shape of the product 100 is circular). In this case, the parison 30 preferably has a circular cross-sectional shape).

  On the other hand, when the cross-sectional shapes of the parison 30 and the product 100 are greatly different, there is a possibility that the thickness of the product 100 varies when the product 100 is molded. For example, when the product 100 having a rectangular cross section is to be molded, if the cross section of the parison 30 is a normal circle, the cross section of the product 100 is thin at the corners and thick at the center of each side. It becomes a rectangle with a non-constant thickness (the corners are thinner than the central part of each side because the amount of deformation of the part corresponding to the corners is the largest when transforming from a circle to a rectangle) Is).

  Therefore, in the present embodiment, a product 700 (FIG. 13B) having a uniform thickness can be obtained even in the above case. That is, as shown in FIG. 13 (a), when the cross-sectional shape of the parison 630 is made circular so that the wall thickness varies in the circumferential direction, A product 700 having a uniform cross section as shown in FIG. Specifically, in the cross section of the parison 630, a thick portion 631 and a thin portion 632 are provided in portions corresponding to the corner portion 701 and the side center portion 702 of the product 700 after deformation, respectively.

  When the cross-sectional shape of the parison 630 is to be changed to a circular shape having a uniform thickness (that is, the inner peripheral surface of the parison 630 is concentric with the outer peripheral surface), the male type of the injection mold 12 is used. Only 14 (male core type 18) needs to be replaced. In this way, a product 700 having a circular cross section can be formed. Therefore, according to the manufacturing method of the present embodiment, the parison 630 corresponding to the product 700 having the circular cross section and the parison 630 corresponding to the product 700 having the rectangular cross section are exchanged only by the male mold 14 (male core mold 18). Any of them can be molded.

(Embodiment 7)
In this embodiment, a blow mold 452 as shown in FIG. 14A is used instead of the blow mold 52 of the first embodiment. Since the blow mold 452 is formed in a mesh shape in which the frame members 453 are combined vertically and horizontally, a parison (not shown) that expands and deforms inside the blow mold 452 is obstructed by the frame member 453. Except for the place where it is done, it can be freely expanded and deformed. Therefore, if such a blow mold 452 is used, a product 800 having irregularities on the surface as shown in FIG. 14B can be formed.

  In the case of the manufacturing method of the present embodiment, the amount of surface irregularities of the product 800 changes depending on the air pressure and molding time during blow molding, so that blow molding can be performed while checking the surface deformation state from the outside. preferable. For this reason, the blow mold 452 is preferably fixed inside a container made of a transparent material such as transparent resin or glass. If it does in this way, the mode of internal blow molding can be observed from the outside of the transparent container.

It is sectional drawing which shows the injection molding machine concerning 1st embodiment of this invention. It is a figure which shows the condition at the time of the mold opening of the said injection molding machine. It is sectional drawing which shows the blow molding machine concerning 1st embodiment of this invention, (a) is the condition before shaping | molding, (b) is the condition after shaping | molding, (c) shows the condition at the time of mold opening. It is a disassembled perspective view which shows the structure of the opening | mouth type | mold holder concerning 1st embodiment of this invention. (A)-(c) is a figure which shows the various modifications of the said opening | mouth type | mold holder. (A) is a perspective view which shows the state of the single-piece | unit of the design member used for a modified example, (b) is a perspective view which shows the state in which the said design member was integrally attached to the product. It is a perspective view which shows the shape of the parison concerning 2nd embodiment of this invention. It is sectional drawing which shows the blow molding machine concerning 2nd embodiment of this invention, (a) shows the condition before shaping | molding, (b) shows the condition after shaping | molding. It is sectional drawing which shows the male core type | mold and female core type | mold used for the injection molding machine concerning 3rd embodiment of this invention. (A) is a perspective view which shows the molding condition of the parison concerning 3rd embodiment of this invention, (b) is a perspective view which shows the product obtained by shape | molding this. It is sectional drawing which shows the blow molding machine concerning 4th embodiment of this invention, (a) is the condition before setting a parison, (b) is the condition after setting a parison, (c) is (b) FIG. It is sectional drawing which shows the blow molding machine concerning 5th embodiment of this invention, (a) is the condition before insertion of an extending | stretching rod, (b) is the condition after inserting an extending | stretching rod, (c) is after completion of blow molding Shows the situation. (A) is a cross-sectional view of a parison according to a sixth embodiment of the present invention, and (b) is a cross-sectional view of a product obtained by molding the parison. (A) is a front view which shows the shape of the blow mold concerning 7th embodiment of this invention, (b) is a front view which shows the shape of the product shape | molded using this.

DESCRIPTION OF SYMBOLS 10 Injection molding machine 12 Injection type 14 Male type 16 Female type 18a Convex part 20a Concave part 22 Cavity space 28 Mouth type holder (holder)
28a Through-hole 30 Parison 30a Opening 30b Bottom 32, 36 Resin inflow path 40 Magnet 50 Blow molding machine 52 Blow mold 58 Molding space 64 Drawing rod 64a Hollow part 64b Air outlet hole 70 Design member 100 Product 170 Design member 254a Circumferential surface 254b Protrusion 256a Bottom surface 256b Protruding part A Blow air

Claims (11)

A method for producing a plastic product in which an injection-molded parison is subsequently molded into a predetermined product shape by blow molding,
By injecting the molten thermoplastic resin into the injection mold with the holder mounted in advance using an injection molding machine including an injection mold, the parison can be attached to one end of the parison. Injection process for molding in a stable state,
Before the molded parison is cured, the parison and the holder are detached from the injection mold, and the parison is transferred from the injection molding machine by holding the holder,
Using a blow molding machine that includes a blow mold having a molding space inside and independent of the injection molding machine, the transported parison is fixed to the inlet of the blow mold by fixing the holder. A blow process of forming a product having a shape corresponding to the molding space by introducing blow air into the parison while holding the parison in an inserted state and further sealing the parison with a predetermined sealing means. Including
The injection mold comprises a male mold having a convex part and a female mold having a concave part corresponding to the convex part, and forming a cavity space corresponding to the shape of the parison between the male mold and the female mold, A resin inflow path for introducing molten resin into the cavity space is provided on both sides of the male mold and the female mold,
In the injection step, the parison is formed by injecting molten resin into the cavity space through the other resin inflow passage in a state where one of the two resin inflow passages provided in the injection mold is closed. A method for producing a plastic product, which is a process of molding In the manufacturing method of the plastic product of Claim 1,
The injection step is to form a cylindrical parison having an opening at one end and a bottom at the other end as the parison, and as a holder when integrating with one end of the parison. A step of using a mouth holder having a through hole so as not to close the opening at one end of the parison,
The sealing means for sealing the parison in the blow step is a plastic product that closes a through hole of a mouth holder attached to one end of the parison while ensuring an introduction path for the blow air. Manufacturing method. In the manufacturing method of the plastic product of Claim 2,
In the blowing step, before or during the introduction of the blow air, the parison is axially moved using an extending rod that can be inserted through the through hole of the mouth holder and press the bottom of the parison from the inner surface side. A method for producing a plastic product, characterized by being a step of drawing and deforming. In the manufacturing method of the plastic product of Claim 3,
The stretching rod includes a hollow portion through which air passes, and an air blowing hole that opens to the surface through the hollow portion,
The method for producing a plastic product, wherein the blowing step is a step of introducing blow air blown out from the air blowing hole into the inside of the parison using the stretching rod. In the manufacturing method of the plastic product of Claim 1,
The injection step forms, as the parison, a cylindrical parison having openings on both sides of the one end and the other end, and when the holder is integrated with one end of the parison, A step of using a mouth holder having a through hole so as not to close the end opening,
The sealing means for sealing the parison in the blowing step closes the through hole of the mouth-type holder attached to one end of the parison while securing the blow air introduction path, and the other end of the parison is blown. A method for producing a plastic product, characterized in that the plastic product is brought into contact with the bottom surface inside the mold. In the manufacturing method of the plastic product of Claim 5,
The blow mold is in close contact with the outer periphery of the other end of the parison, and the bottom surface having a projecting portion that can be fitted into the opening of the other end of the parison in contact with the other end of the parison. A circumferential surface having a circumferential projection that bites into
The blow step is a step of introducing blow air into the parison while fixing the other end of the parison in both the radial direction and the axial direction using the blow mold. . In the manufacturing method of the plastic product of any one of Claims 1-6,
A plastic product manufacturing method, characterized in that a separable holder is used as the holder, and a magnet is embedded in the split surface. In the manufacturing method of the plastic product of any one of Claims 1-6,
A plastic product manufacturing method using a member designed to constitute a part of a product as the holder. In the manufacturing method of the plastic product of any one of Claims 1-8,
The blowing step introduces the designed member by introducing blow air into the parison in a state where a member designed to constitute a part of the product is inserted in the blow mold in advance. A method for producing a plastic product, characterized in that the plastic product is a step of being integrally attached to the outer surface of the plastic product. In the manufacturing method of the plastic product of any one of Claims 1-9,
Production of a plastic product characterized in that the injection process and the blow process are continuously performed in parallel by performing an injection process of forming a new parison in parallel with the blow process. Method. A plastic product manufacturing apparatus for continuously molding an injection-molded parison into a predetermined product shape by blow molding,
In addition to including an injection mold in which a holder can be mounted in advance, by injecting a molten thermoplastic resin into the injection mold, the parison is molded in such a state that the holder is integrally attached to one end thereof. An injection molding machine;
A transfer means for transferring the parison from the injection molding machine by detaching the parison in a state before curing from the injection mold together with the holder, and holding the holder among them;
Including a blow mold having a molding space therein, and holding the parison transferred by the transfer means in an inserted state in the blow mold by fixing the holder to an inlet portion of the blow mold; and In a state where the parison is sealed by a predetermined sealing means, a blow molding machine for molding a product having a shape according to the molding space by introducing blow air into the parison,
The injection molding machine and the blow molding machine are composed of independent facilities,
The injection mold comprises a male mold having a convex part and a female mold having a concave part corresponding to the convex part, and forming a cavity space corresponding to the shape of the parison between the male mold and the female mold, A resin inflow path for introducing molten resin into the cavity space is provided on both sides of the male mold and the female mold,
The injection molding machine injects molten resin into the cavity space through the other resin inflow passage in a state where one of the two resin inflow passages provided in the injection mold is closed. An apparatus for producing plastic products characterized by the above.

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