JP2007136921A - Method for manufacturing thick wall resin container and molding die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a precise molded article by decreasing the kind and number of necessary movable molding dies, decreasing the movable space of the molding dies, improving productivity and preventing the molded article from wrapping so as to dispense with the agreement of the number of layers with the number of molding dies. <P>SOLUTION: The method for manufacturing a thick wall resin container comprises: a process of disposing in parallel a plurality of cavities stepwise thickened with respect to a container shape; a process of injecting a thermoplastic resin into a smallest cavity while concurrently injecting the thermoplastic resin into a remaining space of each cavity except for the smallest cavity after precedently enclosing a container molded in a one step smaller cavity into the cavity; a process of hardening; and a process of taking out a product thick wall container from a largest cavity while concurrently enclosing a container molded in each cavity except for the largest cavity into a one step larger cavity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a thick resin container with high productivity, and also relates to a mold used at that time.

  Conventional methods for manufacturing thick-walled resin molded products, for example, the method of injecting resin into a thick cavity and filling and molding the resin, have a large thermal expansion coefficient, so molding is performed by balancing the thermal expansion coefficient and the cooling rate. There was a problem with sinks in the goods. When slow cooling was performed to prevent sink marks, the thicker the product, the longer it took to solidify and the longer the molding time. As other methods for preventing sink, a method of increasing the cooling rate or a method of filling the resin without gaps by the gas injection method was considered, but there is a limit to increasing the cooling rate, and gas was injected. There was a problem that a dense molded body could not be obtained. In order to solve these problems, the thickness of the cavity is divided into several stages, resin is injected into a cavity that is thin enough to prevent sink marks, and filling is performed multiple times, and the thickness is increased in stages. Lamination molding methods are known.

  In general lamination molding methods, a fixed mold and a movable mold are used as a plurality of molds for forming a cavity, and each movable stage is replaced with another movable mold to support each thickness step. The cavity which forms was formed (for example, refer patent document 1). In the invention described in Patent Document 1, first, the movable mold for forming the minimum cavity is increased by one step in a state where the resin is injected into the minimum cavity and the molded product filled and molded is accommodated in the stationary mold. It was replaced with a movable mold that formed a cavity. Subsequently, a new resin was injected into the newly formed cavity and filled to perform lamination molding. Subsequently, even when three or more layers are formed, the movable mold is replaced with a movable mold that forms a cavity larger by one stage while the molded product is accommodated in the stationary mold, and the size of the cavity is changed in stages. Each time the movable mold was replaced, resin was injected and filled to increase the thickness step by step.

In another general lamination molding method, a cavity corresponding to each thickness stage is formed by moving the movable mold backward with respect to the stationary mold and increasing the distance from each other in stages (for example, patents). Reference 2). In the invention described in Patent Document 2, the movable mold is moved backward with respect to the stationary mold in a state where the molded product is accommodated in the stationary mold, and the distance between the movable molds is increased stepwise. Was injected, filled, and thickened.
JP 2001-191365 A JP-A-7-24867

  In either invention of patent document 1 or 2, the cavity corresponding to each thickness step was formed by exchanging or moving the movable mold including the movable mold and the stationary mold. In particular, the invention disclosed in Patent Document 1 requires the same number of types of movable molds as the number of times of lamination, and the production cost of the molds is great.

  Also, in any of the lamination molding methods of Patent Document 1 or 2, a cavity forming process in which a movable mold moves to form a cavity corresponding to each thickness stage, and an injection process in which resin is injected into the cavity and filled In addition, at least three steps of the solidification step of cooling the molded body in the cavity are set as one set, and this set is performed a plurality of times for lamination, and finally a step of taking out the thick resin product is performed. As a result of performing the above-described series of steps as a set and repeating these steps for lamination, it takes a long time to obtain one molded body, and it cannot be said that the productivity is high. In addition, since the resin is repeatedly cooled and solidified in a mold with a large heat capacity, depending on the molding conditions, the amount of heat shrinkage between the part molded in the previous set and the newly laminated resin in the set In some cases, a problem arises in that warping occurs. Furthermore, in the lamination molding method disclosed in Patent Document 1, since the same number of types of movable molds as the number of times of lamination are required, those movable spaces are also required. In addition, the laminate molding method disclosed in Patent Document 2 is suitable for molding a plate-shaped thick molded product, but it is difficult to integrally increase the bottom and side surfaces of the container. It was unsuitable for molding thick molded articles.

  Therefore, the present invention eliminates the need to match the number of layers and the number of molds, thereby reducing the types and number of movable molds required, reducing the mold movable space, and improving productivity. Furthermore, an object of the present invention is to provide a method for manufacturing a thick resin container capable of suppressing the occurrence of warpage of a molded product and obtaining a highly accurate molded product.

  It is another object of the present invention to provide a mold capable of producing a thick resin container by performing lamination molding with high accuracy and high production efficiency with a single type of mold.

  In the present invention, the respective cavities corresponding to the containers that are gradually increased in thickness toward the outside of the container are arranged in parallel, and each molded product formed by injecting and filling the resin into each cavity is one stage. Move to a large cavity and perform layering sequentially. In addition, the molded product molded in each cavity is moved to one step larger cavity and the product container is taken out in parallel. The present inventors have found that the above problems can be solved by this, and have completed the present invention.

  Specifically, in the method for manufacturing a thick resin container according to the present invention, as a mold for a container having a bottomed cylindrical shape, the inner surface shape of the container is the same or substantially the same, and the outer surface shape is directed outward. Forming a plurality of cavities having a large thickness, and arranging the cavities in parallel so that the main axes of the cavities are parallel to each other, and the heat melted in the smallest of the cavities Injecting and filling the plastic resin, and in parallel with this, a container molded in advance by a smaller cavity is accommodated in each cavity excluding the smallest cavity, with its inner surface in contact. And an injection step of injecting and filling molten thermoplastic resin into the space excluding the space occupied by the container among the internal spaces of the cavities; Solidify the thermoplastic resin to mold each container corresponding to the shape of each cavity, and take out the thick product container that will be the final molded body from the largest cavity among the cavities, in parallel with this And moving the container formed in each cavity excluding the largest cavity among the cavities in a state where the inner surface is in contact with the larger cavity, respectively.

  In the method for manufacturing a thick resin container according to the present invention, it is preferable that the cavity is disposed in the same mold. By placing them in the same mold, the distance between the cavities can be shortened, and the distance to move each container formed in each cavity other than the largest cavity to the cavity forming the next thick-walled stage and the moving time thereof are shortened. can do. For this reason, it is difficult for foreign substances such as dust to adhere to each container, and the yield can be increased.

  Moreover, in the manufacturing method of the thick resin container which concerns on this invention, it is preferable that the said container is thickened by the same thickness stepwise and becomes the said product container. Sinking and distortion can be prevented at each stage. By carrying out lamination molding by dividing into equal thicknesses as much as possible below the maximum thickness that does not cause sink marks, the number of laminations can be reduced and the number of cavities corresponding thereto can be reduced.

  Furthermore, in the method for producing a thick resin container according to the present invention, it is preferable that a polyethylene terephthalate resin is used as the thermoplastic resin, and the cavity is cooled at least in the solidification step. A thick resin container made of polyethylene terephthalate, which has chemical resistance and is not aesthetically devitrified by crystallization, can be produced at low cost and with high productivity.

  Moreover, the metal mold | die which concerns on this invention can solve the said subject by arrange | positioning the cavity of each step for making it thicken in steps toward the outer side of a container with one type of metal mold | die. .

  Specifically, the mold according to the present invention is a mold provided with a cavity serving as a mold for a container having a bottomed cylindrical shape, and the cavity has the same or substantially the same inner surface shape as the outer surface shape. Is a plurality of cavities that are increased in thickness toward the outside, and the cavities are arranged in parallel in the mold so that their main axes are parallel to each other.

  In the mold according to the present invention, it is preferable that each of the cavities is formed to have the same size difference in the container thickness direction from the cavities having different sizes. Sinking and distortion can be prevented at each thick stage. By carrying out lamination molding by equally dividing into the largest possible thickness that is less than the maximum thickness that does not cause sink marks, the number of laminations can be reduced and the number of cavities corresponding thereto can be reduced.

  The manufacturing method of the thick-walled resin container according to the present invention eliminates the need to match the number of layers and the number of molds, thereby reducing the types and the number of movable molds required, and reducing the mold movable space. In addition to reducing the size, it is possible to improve the productivity and to suppress the warpage of the molded product and to obtain a highly accurate molded product. Moreover, with the metal mold | die which concerns on this invention, a thick resin container can be manufactured by performing lamination molding with high precision and high production efficiency with one type of metal mold | die.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The embodiments described below are examples of the present invention, and the present invention is not construed as being limited to these embodiments.

FIG. 1 shows a longitudinal sectional view of one embodiment of a mold according to this embodiment. The mold 100 is a mold provided with a cavity 17 serving as a mold for a container having a bottomed cylindrical shape. The cavity 17 is stepwise with the inner surface shape of the container being the same or substantially the same and the outer surface shape being outward. The cavities 17a, 17b, and 17c are arranged in parallel in the mold 100 so that their principal axes X ₁ , X ₂ , and X ₃ are parallel to each other. . FIG. 1 shows a longitudinal sectional view of a plane passing through the principal axes X ₁ , X ₂ , X ₃ .

FIG. 2 shows a form example of each container formed by the cavities 17a, 17b, and 17c in FIG. Here, (a), (c), and (e) are longitudinal sections passing through the main axes X ₁ , X ₂ , and X ₃ of the containers 20a, 20b, and 20c formed by the cavities 17a, 17b, and 17c, respectively. 4B is a cross-sectional view taken along line AA ′ of the container 20a, FIG. 4D is a cross-sectional view taken along line BB ′ of the container 20b, and FIG. 4F is a cross-sectional view taken along line CC ′ of the container 20c. In the figure, the boundary line when laminated is shown by a dotted line for convenience.

  The container 20 has a bottomed cylindrical shape. The bottom surface of the container 20 may be a curved surface as well as a flat surface. For example, the bottom surface may be a hemispherical surface and may form a side surface and a continuous surface. The cylindrical shape includes a circle as well as an ellipse as well as a polygonal shape such as a quadrangle. Moreover, the outer surface shape includes not only a cylinder but also a truncated cone and a truncated pyramid, for example.

As shown in FIG. 2, in each container 20a, 20b, 20c, the shape of each inner surface 61a, 61b, 61c is the same or substantially the same, and the shape of each outer surface 62a, 62b, 62c is stepped outward in this order. It is thickened. The container 20c that is thickest is the product container. In each container 20a, 20b, 20c, the thickness of the thickness of the side surface and the bottom surface is substantially equal. The thickness of the side wall and the bottom surface of the container 20a is d ₁ , the thickness of the side wall and the bottom surface of the container 20b is (d ₁ + d ₂ ), and the thickness of the side wall and the bottom surface of the product container 20c is (D ₁ + d ₂ + d ₃ ).

  The mold 100 includes a male mold 30 having a convex portion 31 and a female mold 40 having a concave portion 32. Furthermore, the mold 100 preferably includes a split mold 50 that forms a thread for fixing a lid (not shown) on the outer peripheral surface of the peripheral edge of the opening of the container 20. At least the space is sealed by the male die 30 and the female die 40 to form the cavity 17. Each convex part 31a, 31b, 31c is inserted in each concave part 32a, 32b, 32c, respectively, and each cavity 17a, 17b, 17c is formed.

  The cavity 17 in FIG. 1 is a cavity having the same shape as the container 20 in FIG. A plastic resin is injected into the cavity 17, filled, and solidified to mold the container 20. Therefore, the mold 100 preferably has various characteristics required as a plastic injection mold having heat resistance, pressure resistance, releasability, and the like. A plurality of cavities 17 are formed in the mold 100, and the number thereof corresponds to the number of stacked product containers 20c. In FIG. 1, the number of the cavities 17 is three of the cavities 17a, 17b, and 17c, but may be two or four or more.

Each cavity 17a, 17b, 17c and each container 20a, 20b, 20c corresponding to them have the same shape. Accordingly, the main axes X ₁ , X ₂ , X _{3 of the} cavities 17a, 17b, 17c coincide with the main axes of the corresponding containers 20a, 20b, 20c at the time of molding. The main axis X is a center of gravity line.

Further, since the shapes of the cavity 17 and the container 20 match, the thickness of the minimum cavity 17a is d ₁ , the thickness of the cavity 17b is (d ₁ + d ₂ ), and the thickness of the maximum cavity 17c. The thickness is (d ₁ + d ₂ + d ₃ ).

Each of the cavities 17a, 17b, and 17c is preferably formed so that the difference in size in the container thickness direction from the cavities that are different in size by one step is equal. That is, it is preferable that d ₁ = d ₂ = d ₃ . By using the mold 100 in which such cavities 17a, 17b, and 17c are arranged in the method for manufacturing a thick-walled resin container described below, it is possible to prevent the occurrence of sink marks and distortion at each thick-wall stage. . Further, by performing the lamination molding by equally dividing into the largest possible thickness that is less than the maximum thickness that does not cause sink marks, the number of laminations can be reduced and the number of cavities corresponding thereto can be reduced. Therefore, cost reduction and size reduction of the metal mold | die 100 which arrange | positions the cavity 17 can be achieved.

Three-layer lamination molding can be performed using the mold 100 in which the cavities 17a, 17b, and 17c having different thickness stages are arranged. In order to describe the relationship between the cavity 17 and the container 20 more specifically, a process of laminating and forming the container will be described by paying attention to one container. First molding a container 20a having a thickness of _{d 1} with a minimum cavity 17a. Then the container 20a performs laminate molded to thickening the wall thickness _{d 2} minutes housed in the cavity _17b, for molding the wall thickness of the container 20b of _(d 1 + d _2). Then the container 20b performs laminate molded to thickened further thickness _{d 3} minutes meat accommodated in the cavity _17c, molding the wall thickness of the container 20c of _{(d 1 + d 2 + d} 3). In this way, the product container 20c having three layers can be manufactured. Therefore, it is not necessary to replace any or all of the male mold 30 and the female mold 40 with another mold in order to perform the lamination molding, and the lamination molding can be performed using one type of mold 100. it can.

  The container 20 must be able to be extracted from the cavity 17 or accommodated in the next stage cavity. The conditions under which the container 20 can be easily extracted from the cavity 17 and can be easily accommodated in the next-stage cavity will be described below with reference to FIG. In addition, although the container shape | molded by this embodiment does not necessarily satisfy | fill all the following conditions, extraction and accommodation are facilitated by satisfying all.

As a representative of the container 20 and the cavity 17, a description will be given using the container 20a of FIG. By forming the container 20a to satisfy the following (1), (2), and (3), the container 20a can be easily extracted from the cavity 17a and easily accommodated in the cavity 17b. That is,
(1) container 20a is perpendicular to the opening surface of the spindle _{X 1} is the container 20a.
(2) A container 20a, any longitudinal section containing the main axis _{X 1,} the intersection of the outer surface 62a of the cross section and the container 20a of the main axis _{X 1,} the distance between the main axis _{X 1} and _{x 1,} minor section, the cross and the intersection of the outer surface 62a of the cross section and the container 20a of the main axis _{X 1} in a position close to the opening from the surface, and the distance between the main axis _{X 1} and _{x 2, x 1} ≦ _{x 2} is established.
(3) A container 20a, any longitudinal section containing the main axis _{X 1,} the intersection of the inner surface 61a of the cross section and the container 20a of the main axis _{X 1,} the distance between the main axis _{X 1} and _{y 1,} minor section, the cross and the intersection of the inner surface 61a of the cross section and the container 20a of the main axis _{X 1} in a position close to the opening from the surface, and the distance between the main axis _{X 1} and _{y 2, y 1} ≦ _{y 2} is established.

Container 20a is (2) can be pulled out from the recess 32a in the main axis _{X 1} direction by satisfying, can be pulled out from the convex portion 31a on the main axis _{X 1} direction by satisfying the expression (3), (1) By satisfying the above, it can be easily pulled out perpendicular to the opening surface. The container 20a can be accommodated satisfied can be mounted from the main axis _{X 1} direction as the inner surface 61a is in contact with the convex portion 31b by the container 20a to the cavity 17b (3). By satisfying the same conditions for the containers 20b and 20c and the corresponding cavities 17b and 17c, the container 20b can be easily pulled out from the convex portion 31b and the concave portion 32b, and the container 20b is accommodated in the cavity 17c. Can be made. Moreover, the container 20c can be easily pulled out from the convex part 31c and the concave part 32c, and can be taken out as a product container.

In addition to the above (1), (2) and (3), in particular, the cavities 17a, 17b and 17c are arranged in the mold 100 in parallel so that the main axes X ₁ , X ₂ and X ₃ are parallel. By pulling out each container 20a, 20b, 20c in parallel from each convex part 31a, 31b, 31c and each concave part 32a, 32b, 32c forming each cavity 17a, 17b, 17c, and each container 20 can be accommodated in a larger cavity 17 by a series of operations.

  FIG. 3 shows a conceptual diagram of the arrangement relation of the cavities, (a) is a top view of three cavities 101, 102, 103 arranged on the same straight line 120, and (b) is on the same circumference 130. FIG. 6 is a top view of three cavities 111, 112, 113 arranged.

  The main axes of the cavities are perpendicular to the paper surface and are arranged in parallel so that they are parallel to each other. The cavities are preferably arranged at equal intervals in the order of thickness. For example, in FIG. 3A, the cavities 101, 102, and 103 are thickened in this order, and are arranged on the same straight line 120 at equal intervals in the order of the thickness. The arrangement relationship between the cavities 17a, 17b, and 17c shown in FIG. 1 corresponds to FIG. In FIG. 3B, the cavities 111, 112, and 113 are thickened in this order, and are arranged at equal intervals on the same circumference 130 in the order of the thickness. By using a mold in which the cavities 17a, 17b, and 17c are arranged in the pattern of FIG. 3A or FIG. 3B, the containers are taken out from the cavities in parallel, and each container is increased to one step larger cavity. Can be accommodated in a series of operations. Lamination molding can be performed with high production efficiency.

  As shown in FIG. 1, it is preferable that the recesses 32a, 32b, and 32c of the female die 40 are formed with a gate 60 that injects a resin sent through a runner 70 from an injection molding machine (not shown). The gate marks are formed on the outer surfaces 12a, 12b, and 12c of the containers 20a, 20b, and 20c and do not affect the capacity of the container 20. Therefore, the container 20 having a predetermined capacity can be formed uniformly. As the gate 60, a pin gate is preferably used and provided on the bottom surface of each of the recesses 32a, 32b, and 32c. Since the gate mark is formed on the bottom surface of the container 20, it is not conspicuous and does not impair the appearance of the container 20.

  Therefore, with the mold 100 according to the present embodiment, a thick resin container can be manufactured by performing lamination molding with high accuracy and high production efficiency with one type of mold.

  In the mold 100, the cavity 17 is preferably formed by the male mold 30, the female mold 40 and the split mold 50. With the split mold 50, threading can be formed on the outer surface of at least the peripheral edge of the opening of the product container 20c among the containers 20a, 20b, and 20c. By separately manufacturing a lid (not shown) that fits the thread of the product container 20c, excellent sealing performance can be imparted by attaching the lid to the product container 20c.

In order to specifically explain the role of the split mold 50 in the mold 100, the operation of the split mold 50 will be described with reference to FIG. FIG. 4 shows a schematic view when the mold shown in FIG. 1 is viewed in the ZZ ′ section. In FIG. 4, the split mold 50 includes a split mold 50a and a split mold 50b. The cavity 17 can be easily formed even if the outer surface of the peripheral portion of the opening of the container 20 is threaded by closing the split mold 50 in the Y ₁ and Y ₂ directions which are the paper plane directions of FIG. . Further, the container 20 can be easily taken out from the cavity 17 in the main axis X direction even if the split mold 50 is opened by opening in the Y ₁ ′ and Y ₂ ′ directions parallel to the paper surface of FIG.

  The mold 100 may use another split mold instead of the female mold 40. Even the container 20 having a complicated shape that does not satisfy the condition (2) can be easily taken out if it is split. However, in this case, a trace remains at a position corresponding to the split-shaped joint portion on the surface of the product container 20c. In the present embodiment, the outer surface 62 of the container 20 is formed smoothly by using the female mold 40 shown in FIG.

Next, a method for producing a laminated thick resin container using the mold 100 shown in FIG. 1 will be described. The flowchart about the manufacturing method of the thick resin container which concerns on FIG. 5 at this embodiment is shown. Referring to FIGS. 1 and 5, the method for manufacturing a thick resin container according to the present embodiment includes inner surfaces 61 a, 61 b of containers 20 a, 20 b, 20 c as molds for a container 20 having a bottomed cylindrical shape. 61c shape outer surface 62a identical or substantially the same, 62b, each cavity 17a with the shape of 62c to form a plurality of cavities 17 which are stepwise thickened outward, 17b, 17c principal axis of _{X 1} , X ₂ , X ₃ are parallel to each other so that the cavities 17 a, 17 b, 17 c are arranged in parallel, and the molten thermoplastic resin is injected and filled into the smallest cavity 17 a of the cavities 17. In parallel with this, each of the cavities 17b and 17c except for the smallest cavity 17a among the cavities 17 is preliminarily reduced by one step. The containers 20a and 20b formed by 17a and 17b are accommodated in a state where the inner surfaces 61a and 61b are in contact with each other, and the spaces occupied by the containers 20a and 20b are excluded from the internal spaces of the cavities 17b and 17c. An injection step S400 for injecting and filling the molten thermoplastic resin, and solidifying the injected thermoplastic resin to form the containers 20a, 20b, and 20c corresponding to the shapes of the cavities 17a, 17b, and 17c. In step S500, the thick product container 20c, which is the final molded body, is taken out from the largest cavity 17c of the cavities 17, and in parallel with this, molded in each of the cavities 17a and 17b excluding the largest cavity 17c of the cavities 17. The containers 20a and 20b are respectively placed in cavities 17b and 17c that are one step larger, and the inner surface 61a thereof. , 61b, and moving process S600 which accommodates in the state which contacted.

  As shown in the flowchart of FIG. 5, in the method for manufacturing a thick resin container according to the present embodiment, the steps from the start S150 to the end S750 of the thick resin container are the preforming step S250 and the steady forming step. It is divided into S700. The preforming step S250 is a step of preparing for performing the steady forming step S700, and the steady forming step S700 is a step of stably manufacturing the product container. Hereinafter, description will be made with reference to FIGS. 5, 1, and 2.

  In the start S150 of FIG. 5, the cavities 17a, 17b, and 17c are empty. In the pre-forming step S250, from this state, only the minimum cavity 17a is finally empty, and the cavities 17b and 17c accommodate the containers 20a and 20b, respectively. At this time, the containers 20a and 20b are in a state where the inner surfaces 61a and 61b are in contact with the outer surface 11b of the convex portion 31b and the outer surface 11c of the convex portion 31c, respectively.

  The preforming step S250 includes, for example, the following steps (a) and (b). (A) First, the mold 100 is closed, and the molten thermoplastic resin is injected and filled into the minimum cavity 17a formed by closing the mold 100. Next, the thermoplastic resin is solidified to mold the container 20a. Next, the container 20a is taken out from the cavity 17a. Next, the container 20a is accommodated in the cavity 17b with the inner surface 61a in contact with the outer surface 11b of the convex portion 31b.

  (B) Next, the molten thermoplastic resin is injected and filled into the space of the cavity 17a and the space inside the cavity 17b excluding the space occupied by the container 20a. Next, the thermoplastic resin is solidified, and the containers 20a and 20b are formed by the cavities 17a and 17b. Next, each container 20a, 20b is taken out from each cavity 17a, 17b. Next, the containers 20a and 20b are accommodated in the cavities 17b and 17c, respectively, with the inner surfaces 61a and 61b in contact with the outer surface 11b of the convex portion 31b and the outer surface 11c of the convex portion 31c, respectively.

  By the steps (a) and (b), only the minimum cavity 17a is empty, and the cavities 17b and 17c contain the containers 20a and 20b, respectively. At this time, the inner surfaces 61a and 61b of the containers 20a and 20b are in contact with the outer surface 11b of the convex portion 31b and the outer surface 11c of the convex portion 31c, respectively.

  Subsequent to the preliminary molding step S250, a steady molding step S700 is performed. In the steady molding step S700, first, a cavity forming step S300 in which the mold 100 is closed, an injection step S400 for injecting and filling molten thermoplastic resin, and a solidifying step S500 for cooling and solidifying the injected thermoplastic resin are sequentially performed. Do. Next, mold opening S550 is performed. Next, the containers 20a and 20b are taken out from the cavities 17a and 17b other than the maximum cavity 17c, moved to and accommodated in the cavities 17b and 17c which are larger by one stage, and the product container 20c molded with the maximum cavity is taken out in parallel. Then, the moving step S600 is performed.

  Thus, in the steady molding step S700, one cycle is performed from the cavity forming step S300 to the moving step S600. In the steady molding step S700, one product container 20c is manufactured and taken out per cycle. When the cavities 17 are one set of the cavities 17a, 17b, and 17c, the number of product containers 20c that are manufactured and taken out in one cycle is one for each set of cavities. Therefore, increasing the number of product containers manufactured at a time can be realized by providing a plurality of sets of cavities 17 and arranging them in parallel in the mold. For example, by arranging two 17 cavities in parallel so as to form a row, the number of product containers 20c that are manufactured and taken out in one cycle is two.

  Subsequently, confirmation of continuation of manufacturing S630 is performed, and when the product container 20c is continuously manufactured, this cycle may be repeated. When the production is stopped, the end S750 may be performed. In the steady molding step S700, at least one cycle is performed.

  Since the viscosity of the thermoplastic resin is generally sensitive to temperature, the molding accuracy of the container 20 is poor until the mold 100 is stabilized at a predetermined temperature and the viscosity of the thermoplastic resin becomes constant. Therefore, it is preferable to perform one or more cycles in the regular molding step S700 as trial cycles until the viscosity of the thermoplastic resin becomes constant in the preliminary molding step S250, following the steps (a) and (b). By performing the preforming step S250 and the trial cycle until the viscosity of the thermoplastic resin becomes constant, the containers 20a, 20b, and 20c can be accurately molded in the steady molding step S700.

  In the cavity forming step S300, the mold 100 is closed, and the cavities 17a, 17b, and 17c are formed. At this time, each of the cavities 17a, 17b, and 17c is empty only in the minimum cavity 17a, and each of the cavities 17b and 17c contains the containers 20a and 20b (the accommodation state is not shown). At this time, the inner surfaces 61a and 61b are in contact with the outer surface 11b of the convex portion 31b and the outer surface 11c of the convex portion 31c, respectively.

  In this embodiment, since each cavity 17a, 17b, 17c is formed in the same metal mold | die 100, injection process S400 can be performed using one injection molding machine (not shown). Accordingly, in one shot, molten thermoplastic resin is injected and filled into the minimum cavity 17a, and in parallel, in the space excluding the space occupied by the containers 20a and 20b among the internal spaces of the cavities 17b and 17c. The molten thermoplastic resin can be injected and filled.

  The volume of the space excluding the space occupied by the containers 20a and 20b among the internal spaces of the minimum cavity 17a and the respective cavities 17b and 17c may be different. In order to make the injection amount of the thermoplastic resin appropriate for each volume, for example, the shape of the path of the runner 70, the viscosity of the thermoplastic resin, and the injection pressure may be adjusted.

  Examples of the thermoplastic resin include general-purpose resins such as polyethylene, polyethylene terephthalate, polypropylene, polystyrene, acrylonitrile styrene resin, methacrylic resin, and vinyl chloride. These thermoplastic resins have different melting temperatures, and the relationship between temperature and viscosity is also different. Therefore, the temperature at the time of injection is adjusted according to the type of resin in order to have an appropriate viscosity at the time of injection.

  In the solidification step S500, the molten thermoplastic resin injected in the injection step S400 is solidified, and the containers 20a, 20b, 20c corresponding to the shapes of the cavities 17a, 17b, 17c are formed. Since the mold 100 has high thermal conductivity, each of the cavities 17a, 17b, and 17c can efficiently release the heat from the molten thermoplastic resin and at least solidify the surface of the molded body. While the thermoplastic resin is cooled in the cavity 17 while being injected in the injection step S400, in the solidification step S500, by waiting in a state where the mold 100 is closed, at least the surface of the molded body is kept. Cool to the extent that it solidifies. Here, solidification may be semi-solidification in which only the surface is solidified and not completely solidified. In the subsequent moving step S600, if the surfaces of the containers 20a, 20b, 20c are solidified to such an extent that the containers 20a, 20b, 20c are removed from the cavities 17a, 17b, 17c and moved, Good.

  It is preferable that a polyethylene terephthalate resin is used as the thermoplastic resin and the cavity 17 is cooled at least in the solidification step S500. For example, the cavity 17 can be water-cooled by using the mold 100 provided with a water-cooled tube. In the injection step S400, the cavity 17 may be water-cooled, but at least in the solidification step S500, the cavity 17 can be rapidly cooled to such an extent that the polyethylene terephthalate resin is not crystallized. Since the polyethylene terephthalate resin is easily crystallized, it is possible to prevent crystallization by quenching the cavity 17 by water cooling.

  For example, a manufacturing method of a product container 20c made of polyethylene terephthalate resin, which is a cylindrical product container 20c having a diameter of the outer surface 62c of about 6.7 cm and a thickness of about 0.8 cm, will be described. The product container 20c has a three-layer structure in which one layer is about 0.27 cm. A suitable temperature for injecting the melted polyethylene terephthalate resin in the injection step S400 is a temperature between about 240 ° C. and 250 ° C. in the injection molding machine. In this case, in the solidifying step S500, the surface of the container 20 made of polyethylene terephthalate resin is cooled to about 30 ° C. by waiting for about 1 minute while performing water cooling with water having a temperature between about 10 ° C. and 15 ° C. Is done.

  In this way, a product container 20c made of polyethylene terephthalate that has chemical resistance and is aesthetically excellent and not devitrified by crystallization can be manufactured at low cost with high productivity. The product container 20c made of polyethylene terephthalate is suitable for use as, for example, a cosmetic container because it has such characteristics.

  Following the solidification step S500, a mold opening S550 is performed. The mold opening S550 is to separate the male mold 30 and the female mold 40 in the X-axis direction and to separate the split mold 50a and the split mold 50b. At this time, the containers 20a, 20b, and 20c are released from the female mold 40 in a state where the containers 20a, 20b, and 20c are in contact with the convex portions 31a, 31b, and 31c of the male mold 30.

Each of the cavities 17a, 17b, and 17c satisfies the above conditions (1), (2), and (3), and each of the cavities 17a, 17b, and 17c has the respective main axes X ₁ , X ₂ , and X ₃ in parallel. Thus, the container 20 can be easily pulled out from the recess 32 along the X-axis direction during the mold opening S550. Further, a hole for blowing out gas may be provided in the inner surface 12 of the recess 32. The container 20 can be easily released from the recess 32 by blowing out the gas during the mold opening S550.

  In the subsequent moving step S600, a container taking out / moving / accommodating step S610 and a product container taking out step S620 are performed. The container take-out / moving / accommodating step S610 is a step for each of the containers 20a and 20b, and the product container take-out step S620 is a step for the product container 20c. The container take-out / movement / accommodation step S610 is divided into a container take-out step S610a and a movement / accommodation step S610b. By using the container moving means (not shown), the container take-out process S610a and the product container take-out process S620 can be performed in parallel. The container moving means (not shown) is held by a holder (not shown) while maintaining the positional relationship between the containers 20a, 20b, and 20c, and the containers 17a are detached, moved, and attached to the convex portions 31. , 17b, 17c. At this time, the container moving means preferably includes a mechanism for sucking the surface of the container in order to securely hold the container.

  In the moving step S600, first, the container moving means that can suck the outer surface 62 of the container 20 in contact with the convex portion 31 is moved between the male mold 30 and the female mold 40 which are separated from each other. Insert to cross. The container moving means includes, for example, three holder portions, and the outer surfaces 62a, 62b, and 62c of the containers 20a, 20b, and 20c accommodated in the convex portions 31a, 31b, and 31c are sucked by the holder portions, respectively. The holder is held in the holder while maintaining the positional relationship. Next, the container moving means is moved to the female die 40 side in the main axis X direction. Thus, each container 20a, 20b, 20c can be extracted from each convex part 31a, 31b, 31c in parallel by one operation | movement.

  In the container take-out / moving / accommodating step S610, the container take-out step S610a for the containers 20a and 20b and the product container take-out step S620 for the container 20c can be performed in parallel.

  Next, the movement / accommodation step S610b of the container removal / movement / accommodation step S610 will be described. For example, when the cavities 17a, 17b, and 17c have the arrangement relationship shown in FIG. 3A, the container moving means (not shown) is configured such that the main axis X of each of the containers 20a and 20b is the same as the main axis of each of the convex portions 31b and 31c. It moves by the distance between the cavities 17a, 17b, 17c in parallel with the straight line 120 so as to coincide. Subsequently, the container moving means is moved to the male mold 30 side in the main axis X direction, and the containers 20a and 20b are inserted into the convex portions 31b and 31c, respectively. Subsequently, the suction of the container moving means to each of the containers 20a and 20b is stopped. In this manner, the containers 20a and 20b can be detached from the holder portion of the container moving means and brought into contact with the convex portions 31b and 31c, respectively. The container moving means sucks only the product container 20c and passes between the separated male mold 30 and female mold 40 while being held in the holder portion. After finishing passing, the mold 100 is closed. Thus, each container 20a, 20b is accommodated in each cavity 17b, 17c.

  Further, when each of the cavities 17a, 17b, and 17c has the arrangement relationship shown in FIG. 3B, the moving / accommodating step S610b can be performed as in the case of FIG. The container moving means moves along the circumference 130 by the distance between the cavities 17a, 17b, and 17c so that the main axes X of the containers 20a and 20b coincide with the main axes of the convex portions 31b and 31c, respectively. Rotate. Subsequently, the container moving means is moved to the male mold 30 side in the main axis X direction, and the containers 20a and 20b are inserted into the convex portions 31b and 31c, respectively. Subsequently, the suction of the container moving means to each of the containers 20a and 20b is stopped. Next, the containers 20a and 20b can be detached from the holder portion and brought into contact with the convex portions 31b and 31c, respectively. The container moving means passes between the separated male mold 30 and female mold 40 in a state where only the product container 20c is mounted. After finishing passing, the mold 100 is closed. Thus, each container 20a, 20b is accommodated in each cavity 17b, 17c.

  As described above, even if the cavities 17a, 17b, and 17c are arranged as shown in FIG. 3 (a) or FIG. 3 (b), the moving / accommodating step S610b can be easily operated by using the container moving means. Can be done.

  In this embodiment, the distance between each cavity 17a, 17b, 17c can be shortened by arrange | positioning each cavity 17a, 17b, 17c in the same metal mold | die 100. FIG. Therefore, in the moving step S600, the distance and the moving time for moving the containers 20a and 20b formed by the cavities 17a and 17b to the cavities 17b and 17c forming the next thick-walled stage can be shortened. For this reason, it becomes difficult for foreign substances, such as dust, to adhere to each container 20a, 20b, 20c, and it can raise a yield.

  Moreover, in this embodiment, since the distance between each cavity 17a, 17b, 17c is short enough, lamination molding can be performed using one injection molding machine. Therefore, cost reduction and space saving can be achieved. However, when two-color or two-type resins are laminated to produce an integrated product container 20c, two colors or two-type resins are injected into the same mold 100 using two injection molding machines.

  When the manufacture of the product container 20c is continued, the cycle from the cavity forming step S300 to the moving step S600 is repeated again. On the other hand, when it is desired to stop the manufacture of the product container 20c, the process ends S750. When the collection place for collecting the product containers 20c is installed in a place away from the mold 100, only the product container 20c is sucked and mounted while a new cycle is performed in the mold 100. A container moving means can be moved to that location and accumulated there.

In the present embodiment, the product container 20c is a three-layered thick resin container that moves in order through the cavities 17a, 17b, and 17c and is laminated and formed in each. By performing lamination molding, sink and distortion can be prevented. The product container 20c is preferably thickened step by step with the same thickness. That is, when the thicknesses of the cavities 17a, 17b, and 17c are d ₁ , (d ₁ + d ₂ ), and (d ₁ + d ₂ + d ₃ ), respectively, d ₁ = d ₂ = d ₃ Is preferred. The number of layers is reduced and the number of cavities per set corresponding to the number of cavities is reduced by carrying out layering by dividing into equal thicknesses as much as possible with the maximum thickness that does not cause sink. be able to. Therefore, the time required for the preforming step S250 and the trial cycle can be shortened, and thus productivity can be improved.

  The manufacturing method of the thick resin container according to the present embodiment eliminates the need for matching the number of stacked layers and the number of dies, thereby reducing the types and number of necessary movable dies and reducing the movable space of the dies. In addition, the productivity can be improved, and the occurrence of warpage of the molded product can be suppressed, and a highly accurate molded product can be obtained.

It is a longitudinal section of one form of a metallic mold concerning this embodiment. It is an example of each container shape | molded by each cavity in FIG. 1, (a) (c) (e) is a longitudinal cross-sectional view of each container shape | molded by each cavity, (b) is AA 'sectional drawing. , (D) is a BB 'sectional view, and (f) is a CC' sectional view. It is a conceptual diagram of the arrangement | positioning relationship of each cavity, (a) is a case where it arrange | positions on the same straight line, (b) is a case where it arrange | positions on the same periphery. It is the schematic when the metal mold | die shown in FIG. 1 is seen in a Z-Z 'cross section. It is a flowchart about the manufacturing method of the thick resin container which concerns on this embodiment.

Explanation of symbols

11, 11a, 11b, 11c Convex outer surface 12, 12a, 12b, 12c Concave inner surface 17, 17a, 17b, 17c, 101, 102, 103, 111, 112, 113 Cavity 20, 20a, 20b, 20c Container 30 Male mold 31, 31a, 31b, 31c Convex part 32, 32a, 32b, 32c Concave part 40 Female mold 50, 50a, 50b Split mold 60, 60a, 60b, 60c Gate 61, 61a, 61b, 61c Inner surface 62 of container 62a, 62b, 62c Container outer surface 70 Runner S600 Movement process S610 Container removal / movement / accommodation process S610a Container extraction process S610b Movement / accommodation process S620 Product container extraction process S700 Regular molding process

Claims (6)

As a mold for a container having a bottomed cylindrical shape, a plurality of cavities in which the inner surface shape of the container is the same or substantially the same and the outer surface shape is increased in thickness toward the outside are formed, and each cavity is formed A cavity forming step in which the cavities are arranged in parallel so that the principal axes of
Injecting and filling the molten thermoplastic resin into the smallest cavity among the cavities, in parallel, a container molded in advance with a smaller cavity in each cavity excluding the smallest cavity among the cavities. Injecting and filling the molten thermoplastic resin into the space excluding the space occupied by the container among the internal space of each cavity;
Solidifying the injected thermoplastic resin to form each container corresponding to the shape of each cavity;
Take out the thick product container that will be the final molded body from the largest cavity among the cavities, and in parallel to this, the containers molded in each cavity except the largest cavity among the cavities will be made into one larger cavities, respectively. , A moving process for accommodating the inner surface in contact with the inner surface;
A method for producing a thick resin container, comprising:   2. The method for manufacturing a thick resin container according to claim 1, wherein the cavity is disposed in the same mold.   The method for producing a thick resin container according to claim 1 or 2, wherein the container is thickened in steps of the same thickness to become the product container.   The method for producing a thick resin container according to claim 1, 2 or 3, wherein a polyethylene terephthalate resin is used as the thermoplastic resin, and the cavity is cooled at least in the solidification step. In a mold provided with a cavity to be a mold for a container having a bottomed cylindrical shape,
The cavities are a plurality of cavities whose inner surface shape is the same or substantially the same and whose outer surface shape is gradually increased toward the outer side, and the cavities have their main axes parallel to each other. A mold characterized by being arranged in a mold in parallel. 6. The mold according to claim 5, wherein each of the cavities is formed to have the same size difference in the container thickness direction from the cavities having different sizes.

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