JP2006256000A - Method and apparatus for manufacturing plastic product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a plastic product diversified in shape while suppressing a production cost. <P>SOLUTION: In manufacturing the plastic product, first, a preformed body, for example, like a resin lump 30 is molded by injecting a molten thermoplastic resin in the cavity space of an injection mold 12 and, next, the preformed body is transferred to a press mold 42 from the injection mold 12 before curing and further put in a press mold constituted of an upper mold 44 having a protruded part 45 and a lower mold 46 having a recessed part 47 in which the protruded part 45 can be inserted and pressed to mold a product 130 having the shape corresponding to the space between the upper mold 44 and the lower mold 46. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  For example, as shown in Non-Patent Document 1, an injection molding method known as a molding method for thermoplastics is a cavity in which a thermoplastic resin melted (plasticized) by a screw in a heating cylinder (cylinder) corresponds to a product shape. This is a molding method in which a molded product is obtained by injecting and filling a mold having a space inside and then cooling and solidifying the mold. In addition, an injection molding machine used for this molding method includes the screw and the mold in the same facility, and these series of steps are automatically performed in conjunction with each other.

According to such an injection molding method, a product having a complicated shape can be molded automatically at one time, and therefore, it is widely used as a molding method for thermoplastics.
"Plastic Reader (Revised 18th Edition)" by Plastic City Editorial Board of Osaka City Industrial Research Institute and Plastic Technology Association, Plastic Age, published on August 15, 1992

  However, the injection molding method as described above is generally expensive for injection molding machines (injection molds), so if you try to manufacture several types of products with different shapes, what is more expensive injection mold? There was a problem that it was necessary to prepare the types, and the manufacturing cost increased.

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

  In order to solve the above-mentioned problems, the present invention is a method for producing a plastic product, in which a preformed injection-molded body is subsequently molded into a predetermined product shape by press molding, and is a thermoplastic resin melted in a cavity space in an injection mold An injection process for forming a preform by injecting the preform, a transfer process for transporting the preform from the injection mold to the press mold before the preform is cured, and an upper mold having a convex portion. A product having a shape corresponding to the space between the upper mold and the lower mold is obtained by sandwiching and pressing the preformed body between a press mold composed of a lower mold having a recess into which the convex portion can be inserted. And a pressing step for molding.

  According to the manufacturing method of the present invention, the preform is molded once by the injection process, and then the product is molded by performing the pressing process on the preform, so that the product weight is almost the same. If it exists, a product with a different shape can be formed by replacing only the press mold while forming a common preform using the same injection mold. In other words, the injection mold is much more expensive than the press mold due to its complicated structure. If the product is to be molded only by the injection process, it is necessary to replace the injection mold even by slightly changing the product shape. In contrast, when the injection process and the press process are used together as in the present invention, the injection mold can be used as it is, and it can be dealt with by replacing a much cheaper press mold. It is possible to suppress an increase in mold cost due to the shape change. According to this method, naturally, an extra press molding machine is required, but even in that case, if a product of various shapes is to be molded only by the injection process, a large and high-performance injection molding machine is required. On the other hand, if it is only necessary to form a preform with a simple shape at the stage of the injection process as in the manufacturing method of the present invention, a relatively inexpensive injection molding machine can be used. Is much cheaper than an injection molding machine, so that it is possible to reduce the manufacturing cost as a whole rather than dealing with a wide range of product shapes using only an injection molding machine.

  Furthermore, according to the manufacturing method of the present invention, the injection process is terminated before the preform is cured, and press molding is performed on the preform before it is cured. Is also advantageous. That is, when the product is molded only by the injection process, it is necessary to hold it in the injection mold until the resin is completely cured, whereas in the manufacturing method of the present invention, the injection process is performed before the resin is cured. Because it is completed, the holding time in the injection mold can be shortened significantly, and the preform is directly pressed against the preform before curing. Therefore, even if some time is required for the transfer process and the pressing process, the time required for product molding can be reduced as a whole.

  However, also in this manufacturing method, when the weight of a product changes considerably, it is necessary to change the size (shape) of the preform. In that case, as the injection mold, a core mold that constitutes a part of the mold is provided therein, and an injection mold including the cavity space in the core mold is used, and the injection process is performed using the injection mold. It is preferable that the preform is molded into a cavity space in the core mold using a mold.

  According to this configuration, since the preform is molded into the cavity space in the core mold provided inside the injection mold, the size of the preform is changed by replacing only the core mold without replacing the injection mold itself. Therefore, it is possible to further suppress an increase in mold cost accompanying a change in product shape.

  Preferably, during the pressing process, the injection process and the pressing process are performed in parallel by performing an injection process for forming a new preform for the next pressing process in parallel. It is good to carry out continuously. In other words, a preformed body is formed by the injection process, and while the pressing process is performed on the preform, an injection process for forming a new preformed body is started immediately and this is repeated thereafter. is there. In this way, the product molding cycle time can be made significantly shorter than the total time from the injection process to the pressing process.

  Furthermore, preferably, the injection molding is performed by integrating the preform with the holder by using an injection mold in which a holder having an inner peripheral surface that comes into contact with the outer periphery of the preform is mounted in advance. It is preferable to carry out the molding, and to carry out the transferring step by holding the holder and transferring the preform together with the holder from the injection mold to the press mold.

  According to this configuration, the preformed body is formed integrally with the holder by the injection process, and the preformed body is transferred while holding the holder by the transfer process. However, it can be easily held and transferred without losing its shape.

  Here, in the injection step, various shapes can be molded as the preform, but a single block of resin may be molded as the preform. In this case, the transfer step is performed such that after the resin mass is transferred to the press mold together with the holder, the resin mass is detached from the holder so that only the resin mass is put into the recess of the lower mold. Good.

  When a container-shaped product is molded as a product, a container-shaped parison having one end opened as the preform and a bottom at the other end may be molded. In this case, the injection process is performed using a mouth holder that has a hole substantially the same shape as the opening of the parison and is integrated with the periphery of the opening of the parison as the holder, and further the transfer process. The parison may be transported to the press mold together with the mouth mold holder, and the mouth holder may be fixed to the entrance of the recess of the lower mold so as to hold the parison in the inserted state.

  According to this configuration, since the container-shaped parison is formed as a preform, the shape is already relatively close to the product at the time of the preform, so that the shape of the parison is greatly deformed in the pressing process. Therefore, the time required for the pressing process can be shortened. Moreover, it becomes the structure which hold | maintains a parison in the said insertion state in the said recessed part by fixing the mouth type holder integrated with the opening part periphery of the parison by the injection process as it is to the recessed part entrance of the lower mold | type of a press type | mold. Therefore, the parison can be set in the press die in a stable posture, and as a result, problems such as uneven thickness during press molding can be made difficult to occur.

  Here, about the said holder, when it is necessary to remove this from a product after product shaping | molding, it is preferable to embed a magnet in the division | segmentation surface using the holder which can be divided | segmented as a holder. If it does in this way, while the operation | work which removes a holder from a product can be easily performed by dividing | segmenting a holder, the holder once divided | segmented can be easily rejoined.

  On the other hand, in a container-shaped product, a member designed to constitute a part of the product may be attached to the opening. In such a case, if the design member is used as the mouth holder, it is not necessary to attach it in a later process, and the manufacturing efficiency can be increased.

  According to the manufacturing method as described above, products having various shapes as described below can be formed. For example, if the pressing step is performed by using an upper mold having a cylindrical convex portion with a thread surface formed on the outer periphery as the upper mold, a hollow product having an internal thread on the inner surface can be formed. . In this case, when the upper die is detached from the product, the upper die may be extracted from the product by rotating the upper die.

  In addition, the pressing step is deformed by pressing the preform with a lower mold having a recess in which a space larger than the entrance portion is formed and a flexibility that can follow the shape of the recess. By using a press die provided with an upper die having a convex portion made of an elastic body having a strength capable of being molded, a hollow product having an axial section convex outward is formed. be able to. For example, urethane rubber may be used as the material of the convex portion of the upper mold.

  Further, if the pressing step is performed by pressing the preform in a state where a member designed to constitute a part of the product is inserted in the recess of the lower mold in advance, the design member is the product. Can be integrated with the outer surface of the.

  In addition, the injection step is performed by molding a plurality of resin lumps in a lump as the preform, and the pressing step is performed by overlapping the resin lumps and sandwiching a decorative part therebetween, If the overlapped resin mass is pressed, the decorative part can be integrated with the product in such a manner as to be embedded in the product. In this case, it is preferable to use a resin having transparency that allows the inside to be seen as a resin material.

  As described above, according to the method for manufacturing a plastic product of the present invention, it is possible to mold products having various shapes while suppressing the manufacturing cost.

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

1) Injection Step This step is a step of molding a resin mass 30 as a preformed body by injecting a molten thermoplastic resin into the injection mold 12 of the injection molding machine 10 shown in FIG.

  The injection mold 12 has a structure in which a movable mold 13 and a fixed mold 14 are opposed to each other. Inside this injection mold 12, a core mold 20 that constitutes a part of the mold and has a cavity space (a space corresponding to a molded product) is mounted, and molten resin is contained in the cavity space. By filling, a block of resin mass 30 is formed. Therefore, when it is desired to mold resin lumps 30 having different sizes, only the core mold 20 needs to be replaced (the fixed mold 14 and the movable mold 13 do not need to be replaced). If unnecessary depending on the situation, the core mold 20 may be omitted, and the resin block 30 may be directly molded between the movable mold 13 and the fixed mold 14.

  The core mold 20 includes a first core mold 24 mounted on the inner surface of the movable mold 13 and a second core mold 26 mounted on the inner surface of the fixed mold 14. The movable mold 13 and the first core mold 24, and the fixed mold 14 and the second core mold 26 are detachably coupled by magnets 34 embedded in the respective members. When the first core mold 24 and the second core mold 26 are detachably fixed with a certain amount of fitting force, the magnet 34 can be omitted. Further, since the second core mold 26 does not detach from the fixed mold 14 during the injection process, it may be completely fixed to the fixed mold 14 with a bolt or the like.

  The first core mold 24 has a positioning guide pin 25 projecting on the mating surface with the second core mold 26, and the guide pin 25 corresponds to the second core mold 25. It is configured to be inserted into a hole recessed in the core mold 26. Note that the guide pin 25 may be omitted if unnecessary according to circumstances.

  Here, the resin lump 30 molded inside the core mold 20 is fused to some extent to the inner peripheral surfaces of the first core mold 24 and the second core mold 26. As shown in the drawing, the contact area is larger in the first core mold 24 than in the second core mold 26, so that the resin mass 30 is more strongly bonded to the first core mold 24. It has become. Therefore, when the injection mold 12 is opened, the resin mass 30 follows the first core mold 24 and is detached from the second core mold 26. That is, the first core mold 24 maintains the state integrated with the resin mass 30 even after the mold is opened. In the transfer step described later, the resin mass 30 is transferred by holding the first core mold 24. Thus, the first core mold 24 also serves as the holder 22 that holds the resin mass 30. Hereinafter, this member will be referred to as the holder 22 instead of the first core mold 24. In addition, in order to reduce the burden accompanying transfer, as a material of the holder 22, for example, a lightweight aluminum alloy may be used.

  As shown in FIG. 2, the holder 22 has a divided structure including component parts 22a and 22b. Thereby, the work of removing the resin mass 30 to be performed later from the holder 22 can be easily performed by dividing the holder 22. A magnet 34 is embedded in each divided surface of the component parts 22a and 22b. Thereby, the holder 22 once divided can be easily re-coupled. If there is no problem depending on the situation, the holder 22 may be an integrated product (cannot be divided) (in this case, the magnet 34 on the divided surface of the holder 22 is naturally not necessary).

  Returning to FIG. 1 again, the fixed mold 14 is connected to a nozzle 18 which is an injection portion of a screw (not shown) for melting (plasticizing) and injecting a resin as a raw material. 18 flows into the fixed mold 14. A flow path that penetrates the stationary mold 14 and the second core mold 26 is provided so as to connect the cavity space in the core mold 20 from the nozzle 18, and a gate portion 32 (an inlet portion of the molded product) is provided there. Molded. The gate portion 32 has a shape bent at two locations along the flow path, and a pin gate portion 32a narrowed in a small hole shape is formed at the tip thereof. Thus, when the injection mold 12 is opened, the resin lump 30 and the gate portion 32 are divided at the pin gate portion 32a, so that only a minimum gate trace remains in the resin lump 30. . The fixed mold 14 has a divided structure composed of three mold plates, ie, a first mold plate 15, a second mold plate 16, and a third mold plate 17. When the mold is opened, the three mold plates are used. As a result of the separation, the gate portion 32 automatically drops off. If not particularly required, the shape of the gate portion 32 may be a direct connection type (direct gate) and the fixed die 14 may be integrated. In this case, the gate portion 32 remains in the resin lump 30 when the die is opened. The operation | work which cut | disconnects the part 32 is needed.

  The movable die 13 is provided with an ejector pin 36 that is slidable in the axial direction, and its tip abuts against the holder 22. When the mold is opened, the ejector pin 36 protrudes and the holder 22 is pushed out. Thereby, even if the holder 22 and the movable mold | type 13 are couple | bonded by the magnet 34, the holder 22 can be made to detach | leave from the movable mold | type 13, and the resin lump 30 can be taken out easily.

  In the procedure of molding the resin mass 30 by the injection molding machine 10 as described above, first, molten resin is injected from the nozzle 18 by a screw not shown. Then, the molten resin is filled into the cavity space in the core mold 20 through the flow path in the fixed mold 14, and the resin lump 30 corresponding to the shape of the cavity space is molded.

  Then, before the resin mass 30 is cured, the injection mold 12 is opened by moving the movable mold 13 in the direction away from the fixed mold 14 as shown in FIG. At this time, the resin mass 30 is detached from the second core mold 26 and integrated with the holder 22 as described above. Accordingly, when the ejector pin 36 provided on the movable mold 13 is protruded after the mold is opened and the holder 22 is pushed out, the resin mass 30 is pushed out of the movable mold 13 together with the holder 22 and is released. The gate portion 32 is separated from the resin mass 30 at the pin gate portion 32a when the die is opened, and the fixed die 14 is separated from the fixed die 14 and dropped off as shown in the figure.

2) Transfer process This process is a process of transferring the resin mass 30 in the state before curing formed by the injection process to the press molding machine 40 shown in FIG. 4 before it is cured. Specifically, the holder 22 and the resin lump 30 (FIG. 3) taken out integrally from the injection mold 12 are transferred to the press molding machine 40 by holding the holder 22 among them. Then, the resin mass 30 is separated from the holder 22 by dividing the holder 22, and only the resin mass 30 is put into the press die 42 (FIG. 4). The transfer may be performed by a machine or by a person.

  In this embodiment, the means for holding the holder 22 integrated with the outer surface of the resin mass 30 is used as a means for transferring the resin mass 30 in a state before being cured. When the holder 22 (also serving as the first core mold 24) is omitted, it is necessary to separately prepare a means for holding the resin mass 30 such as a tray.

3) Pressing step This step is a step of forming the resin lump 30 transferred in the transferring step into a predetermined product shape by sandwiching and pressing the resin lump 30 in the press mold 42 of the press molding machine 40 shown in FIG. It is.

  The press die 42 includes an upper die 44 and a lower die 46. The upper mold 44 has a convex portion 45, and the lower mold 46 has a concave portion 47 into which the convex portion 45 can be inserted, and a space corresponding to the shape of the product is formed between the convex portion 45 and the concave portion 47. It has come to be. The lower mold 46 is provided with a presser lid 48 at the entrance of the recess 47 for preventing the resin mass 30 that has been pressed and deformed from protruding to the outside and forming the edge of the molded product.

  In the procedure of press molding the resin lump 30 using such a press molding machine 40, first, the resin lump 30 is arranged in the recess 47 of the lower mold 46 as shown in FIG. And the convex part 45 of the upper mold | type 44 is inserted in the said recessed part 47, and the upper mold | type 44 is pressed in an insertion direction with the mold clamping apparatus not shown. Then, the uncured resin mass 30 is compressed and deformed into a thin wall shape as shown in FIG. 4B, and finally a product 130 having a shape corresponding to the space between the convex portion 45 and the concave portion 47. Is formed.

  Here, the time required for forming the product 130 by the above process (on average, depending on the shape and material of the product 130) is about 10-15 seconds for the injection process. Since the time required for the pressing process is about 5 seconds each, if one process is performed in order, the total time is about 20 to 25 seconds. However, here, the injection process and the pressing process are continuously performed in parallel to further reduce this time. That is, while the resin lump 30 is molded by the injection process and the product 130 is molded by performing a pressing process on the resin lump 30, the injection process for forming a new resin lump 30 is immediately started. Repeat this. For this purpose, it is necessary to prepare a plurality of holders 22.

  According to this configuration, since the injection process and the pressing process are performed in parallel, the cycle time for molding the product 130 is only one of the processes (more precisely, the process that requires more time). It will be. Specifically, since the time required for the injection process (about 10 to 15 seconds) is longer than the time required for the pressing process (about 5 seconds), the cycle time is 10 to 10 times that is required for this injection process. This is about 15 seconds, which is much shorter than the above-mentioned 20 to 25 seconds, which is the total time from the injection process to the pressing process.

  However, even if the process is sequentially performed from the injection process to the pressing process one by one, it is possible to mold the product 130 in a shorter time than molding the product 130 only by the injection process. This is because when the product 130 is to be molded only by the injection process, it is necessary to hold the resin 130 in the injection mold 12 until the resin is completely cured. Therefore, it is considerably long until the injection mold 12 is opened and the product 130 is taken out. Whereas time (about 30 seconds) is required, when the injection mold 12 is opened before the resin is cured as in the present embodiment, the time required for the injection process can be significantly reduced (10 to 15 seconds). Therefore, even if a certain amount of time (about 10 seconds) is required for the post-process (transfer process and press process), the product 130 can be molded in a short time as a whole.

  As described above, according to the manufacturing method of the present embodiment, the resin mass 30 is once molded by the injection process, and then the product 130 is molded by performing a pressing process on the resin mass 30. Therefore, if the weight of the product 130 is substantially the same, the product 130 having a different shape can be formed by replacing only the press die 42 while forming the common resin mass 30 using the same injection die 12. Further, since the core mold 20 is provided inside the injection mold 12 and the resin lump 30 is molded therein, the injection mold 12 itself is not replaced even when the weight of the product 130 is changed. This can be dealt with by replacing only the core mold 20. On the other hand, if the product 130 is to be molded only by the injection process, the injection mold 12 (the injection mold 12 is much more expensive than the press mold 42 because the structure is complicated) even if the shape is slightly changed. Therefore, the manufacturing method according to the present embodiment can suppress an increase in mold cost due to the shape change of the product 130. According to this method, the press molding machine 40 is naturally necessary, but even in that case, if a product 130 having various shapes is to be molded only by the injection process, the large-sized and high-performance injection molding machine 10 is required. Whereas it is necessary, if it is only necessary to mold the resin block 30 having a simple shape at the stage of the injection process as in the present embodiment, it can be handled by a relatively inexpensive injection molding machine 10, and further, press Since the molding machine 40 is much cheaper than the injection molding machine 10, it is possible to reduce the manufacturing cost as a whole rather than dealing with a wide range of product shapes with the injection molding machine 10 alone.

  In this embodiment, in the pressing process, the upper die 44 having a convex portion 45 with a flat outer surface is used. However, the convex portion 45 is replaced with a cylindrical member having a threaded surface formed on the outer periphery. For example, a female screw can be formed on the inner surface of the product 130. In this case, the work of extracting the upper mold 44 from the product 130 after press molding needs to be performed by rotating the upper mold 44.

  In the pressing process, a member designed to constitute a part of the product 130 is inserted in advance into the inner peripheral surface of the recess 47 of the lower mold 46, and the resin lump 30 is pressed in that state. For example, the design member can be integrated with the outer surface of the product 130.

(Embodiment 2)
1) Injection Process In the first embodiment, the single-piece resin mass 30 was molded as a preform by the injection process. However, in the second embodiment, as shown in FIG. A container-like parison 50 having an opening and a shallow bottom at the other end is formed.

  The parison 50 is formed in a cavity space in the core mold 120 inside the injection mold 12. The core mold 120 is composed of a convex first core mold 124 and a concave second core mold 126, and a cavity space corresponding to the parison 50 is formed therebetween. In the present embodiment, both the first core mold 124 and the second core mold 126 are not detached from the injection mold 12 during this process, and are therefore completely fixed to the injection mold 12 with bolts or the like. However, it may be detachably fixed by a magnet or the like as in the first embodiment.

  Further, the first core mold 124 is fitted with a ring-shaped mouth holder 122 having an inner diameter substantially equal to the opening of the parison 50, and the periphery of the opening of the parison 50 is formed on the inner peripheral surface thereof. Such a groove 122c is provided. A magnet 34 is embedded in each mating surface of the first core mold 124 and the mouth mold holder 122, and the mouth holder 122 is detachably fixed to the first core mold 124. Although not shown, the mouth holder 122 can be divided like the holder 22 of the first embodiment so that the mouth holder 122 can be easily removed from the product 150 (FIG. 6) after the pressing process. The magnet 34 is embedded in the divided surface.

  The ejector pin 36 provided on the movable die 13 penetrates the movable die 13 and the first core die 124 and is in contact with the mouth holder 122, and protrudes when the injection die 12 is opened so that the mouth holder 122 is moved. It is configured to extrude. At this time, since the opening periphery of the parison 50 is integrated with the mouth holder 122, the parison 50 is pushed out together with the mouth holder 122 and detached from the injection die 12.

2) Transfer process Next, the parison 50 is transferred to the press molding machine 40 shown in FIG. 6 by holding the mouth holder 122, and the parison 50 is pressed while maintaining the integrated state of the parison 50 and the mouth holder 122. Set in the mold 42. Specifically, the parison 50 is held in the recess 47 in an inserted state by fixing the mouth mold holder 122 to the entrance of the recess 47 of the lower mold 46.

3) Pressing process Then, press molding is performed on the parison 50 held in the recess 47 of the lower mold 46 as shown in FIG. At this time, the convex portion 45 of the upper mold 44 passes through the mouth mold holder 122 and presses the parison 50. Finally, as shown in FIG. 6B, a container-shaped product 150 in which the shape of the parison 50 is directly stretched is formed.

  According to the second embodiment as described above, since the shape of the parison 50 that is a preform is already relatively close to the product 150, it is not necessary to significantly deform the shape of the parison 50 in the pressing process. The time required for the process can be shortened. In addition, by fixing the mouth holder 122 integrated with the opening periphery of the parison 50 to the entrance of the recess 47 of the lower mold 46, the parison 50 can be held in the recess 47 in a stable posture. Problems such as uneven thickness during press forming can be made difficult to occur.

  In the present embodiment, the mouth holder 122 is configured to be separable and removed from the opening of the product 150 after the pressing process. However, depending on the type of the product 150, a part of the product 150 is inserted in the opening. In some cases, members designed so as to constitute the above are integrally attached. In such a case, if the design member is used as the mouthpiece holder 150, the attachment is already completed at the time of the injection process, so that it is not necessary to attach it in the subsequent process, and the manufacturing efficiency can be improved.

(Embodiment 3)
In this embodiment, in the pressing step shown in FIG. 7, a hollow container-shaped product having a convex portion 145 made of an elastic body as the upper mold 44 and having an axial cross section convex outward. 230 is formed. Here, since the injection process and the transfer process are the same as in the first embodiment, only the pressing process will be described.

  As shown in FIG. 7A, the press die 42 of this embodiment includes an upper die 44 having a convex portion 145 made of an elastic body, and a concave portion 147 in which a space larger than the inlet portion is formed. The resin lump 30 that is configured by the lower mold 46 and that is molded by the injection process is sandwiched between the convex portions 145 and the concave portions 147 and pressed.

  The convex portion 145 is made of urethane rubber, which is an elastic body having flexibility that can follow the shape of the concave portion 147 and strength that can press and deform the resin lump 30. The interior is hollow so as to be flexible. For this reason, when the upper die 44 is further pressed from a state in which the tip of the convex portion 145 inserted into the concave portion 147 is in contact with the upper surface of the resin lump 30, the convex portion 145 becomes the concave portion as shown in FIG. Elastically deforms so as to follow the shape of 147.

  Therefore, if such a press die 40 is used, even if a space larger than the entrance portion is formed inside the concave portion 147, the resin mass 30 is uniformly distributed between the concave portion 147 while the convex portion 145 is elastically deformed. Can be pressed. As a result, it was impossible to mold by the conventional press molding method (in the past, it was molded by a method of blowing air into a bottomed cylindrical preform, for example, called a blow molding method) It becomes possible to form a hollow container-shaped product 230 whose axial cross section is convex outward. Further, the work of detaching the upper mold 44 from the product 230 can be easily performed because the elastic deformation of the convex portion 145 is released if the mold clamping force is loosened.

  In this embodiment, the resin lump 30 similar to that of the first embodiment is formed as a preform and the above-described press molding is performed on the resin lump 30. However, the parison 50 is formed as in the second embodiment. Of course, it is also possible to perform the same press molding as this time on the parison 50 by molding the mouth mold holder 122 integrally.

(Embodiment 4)
The manufacturing method of the present embodiment is a method of forming a product 330 in which the decorative part 60 is embedded, as shown in FIG. Specifically, first, as shown in FIG. 8A, in the injection step, a plurality of one-piece resin lumps 30 are formed, the plurality of resin lumps 30 are overlapped, and the decorative component 60 is sandwiched therebetween. As this decorative part, it is preferable to use a flexible member that can be easily deformed, such as a pressed flower. Then, the decorative part 60 is integrated with the resin by performing press molding on the resin mass 30 in which the decorative part 60 is sandwiched inside as described above, and the decorative part 60 is integrated inside as shown in FIG. A product 330 in which the component 60 is embedded is molded. In this case, it is preferable to use a resin material having such a transparency that the decorative component 60 embedded in the product 330 can be seen from the outside.

It is sectional drawing which shows the injection molding machine concerning 1st embodiment of this invention. It is a disassembled perspective view which shows the structure of the holder with which the inside of the said injection molding machine is mounted | worn. 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 press molding machine concerning 1st embodiment of this invention, (a) shows the condition before a press, (b) shows the condition after a press. It is sectional drawing which shows the injection molding machine concerning 2nd embodiment of this invention. It is sectional drawing which shows the press molding machine concerning 2nd embodiment of this invention, (a) shows the condition before a press, (b) shows the condition after a press. It is sectional drawing which shows the press molding machine concerning 3rd embodiment of this invention, (a) shows the condition before a press, (b) shows the condition after a press. It is a figure which shows the manufacturing method concerning 4th embodiment of this invention, (a) is the condition which piles up a resin lump, (b) shows the condition of the product obtained by press-molding this.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Injection molding machine 12 Injection mold 20,120 Core mold 22 Holder 30 Resin lump 34 Magnet 40 Press molding machine 42 Press mold 44 Upper mold 45 Convex part 46 Lower mold 47 Concave part 50 Parison 60 Ornamental part 122 Mouth type holder 130,150 , 230, 330 products

Claims (14)

A method for producing a plastic product in which a preform formed by injection molding is subsequently molded into a predetermined product shape by press molding,
An injection step of forming a preform by injecting a molten thermoplastic resin into the cavity space in the injection mold;
A transfer step of transferring the preform from the injection mold to the press mold before the preform is cured;
A space between the upper mold and the lower mold is formed by sandwiching and pressing the preform between a press mold composed of an upper mold having a convex part and a lower mold having a concave part into which the convex part can be inserted. And a pressing process for forming a product having a shape corresponding to the above. In the manufacturing method of the plastic product of Claim 1,
As the injection mold, a core mold that constitutes a part of a mold is provided therein and an injection mold including the cavity space inside the core mold is used.
The method of manufacturing a plastic product, wherein the injection step is a step of forming the preformed body in a cavity space in the core mold using the injection mold. In the manufacturing method of the plastic product of Claim 1 or 2,
While performing the pressing process, performing the injection process and the pressing process continuously in parallel by performing the injection process of forming a new preform for the next pressing process in parallel. A method for producing a plastic product characterized by the above. In the manufacturing method of the plastic product of any one of Claims 1-3,
The injection step is a step of forming the preform integrally with the holder by using an injection mold in which a holder having an inner peripheral surface that comes into contact with the outer periphery of the preform is mounted in advance. And
The method of manufacturing a plastic product, wherein the transferring step is a step of holding the holder and transferring the preform together with the holder from an injection die to a press die. In the manufacturing method of the plastic product of Claim 4,
The injection step is a step of molding a lump resin lump as the preform.
The transfer step is a step of transferring only the resin mass into the concave portion of the lower mold by removing the resin mass from the holder after the resin mass is transferred to the press die together with the holder. Manufacturing method of plastic products. In the manufacturing method of the plastic product of Claim 4,
The injection step is a step of forming a container-shaped parison having one end opened as the preform and the other end having a bottom, and the holder has a hole substantially in the same shape as the parison opening. A step of using a mouth holder that is integrated with the periphery of the opening of the parison,
The transfer step is a step of holding the parison in an inserted state in the recess by transferring the parison to the press die together with the mouth holder and fixing the mouth holder to the entrance of the recess of the lower mold. A method for producing a plastic product. In the manufacturing method of the plastic product of any one of Claims 4-6,
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 Claim 6,
A plastic product manufacturing method using a member designed to constitute a part of a product as the mouth holder. In the manufacturing method of the plastic product of any one of Claims 1-8,
The pressing step is a step of forming a female screw on the inner surface of the product by using an upper die having a cylindrical convex portion with a thread surface formed on the outer periphery as the upper die,
A method for producing a plastic product, wherein the means for releasing the upper mold from the product is a means for removing the upper mold from the product by rotating the upper mold. In the manufacturing method of the plastic product of any one of Claims 1-8,
As the press die, there is a lower die having a recess in which a space larger than the entrance portion is formed, a flexibility that can follow the shape of the recess, and the preform is pressed and deformed. Using a press die provided with an upper die having a convex portion made of an elastic body having a strength as much as possible,
The method of manufacturing a plastic product, wherein the pressing step is a step of forming a hollow product having an axial section convex outward using the press die. In the manufacturing method of the plastic product of Claim 10,
A method for producing a plastic product, characterized in that urethane rubber is used as the material of the convex part of the upper mold. In the manufacturing method of the plastic product of any one of Claims 1-11,
In the pressing step, the designed member is integrated with the product by pressing the preform in a state where a member designed to constitute a part of the product is inserted in the recess of the lower mold in advance. A method for producing a plastic product, characterized in that it is a process of making a plastic product. In the manufacturing method of the plastic product of any one of Claims 1-4,
The injection step is a step of molding a plurality of lump resin lump as the preform.
In the pressing step, the plurality of resin lumps are overlapped, a decorative part is sandwiched between them, and the superimposed resin lumps are pressed so that the decorative part is embedded in the product and integrated with the product. The process of
A method for producing a plastic product, comprising using a resin having a transparency that allows the inside to be seen as a resin material. An apparatus for producing a plastic product, in which a preform formed by injection molding is subsequently molded into a predetermined product shape by press molding,
An injection molding machine that molds a preform by injecting a molten thermoplastic resin into the cavity space in the injection mold;
Transfer means for transferring the preformed body before curing from the injection molding machine to the press molding machine;
A space between the upper mold and the lower mold is formed by sandwiching and pressing the preform between a press mold composed of an upper mold having a convex part and a lower mold having a concave part into which the convex part can be inserted. An apparatus for producing a plastic product, comprising: a press molding machine that molds a product having a shape corresponding to the above.

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