Injection molding die, and resin container manufacturing device and manufacturing method

Abstract

This injection molding die, which is applied to injection molding of a bottomed cylindrical preform made of resin, includes: an injection cavity mold that defines the outer peripheral shape of the preform; and an injection core mold that is inserted into the injection cavity mold. The injection core mold includes: a base portion which is attached to a fixed plate that drives the injection core mold forward and backward, and which can be rotationally operated in the circumferential direction with respect to the fixed plate; and a die main body portion which is disposed on a distal end side of the base portion and which defines the inner peripheral shape of the preform. The central axis of the die main body portion is offset with respect to the central axis of the injection cavity mold and the base portion. In addition, the injection molding die is capable of adjusting the circumferential positions of a first site where a gap between the injection cavity mold and the die main body portion is small, and a second site in which the gap is larger than at the first site, in association with the rotation of the injection core mold.

Description

Injection molding die, resin container manufacturing device and manufacturing method

[0001] The present invention relates to an injection molding die, and a manufacturing apparatus and manufacturing method for a resin container.

[0002] A hot parison type blow molding machine has been known as one type of apparatus for manufacturing resin containers. A hot parison type blow molding machine is configured to blow mold a resin container by utilizing the heat retained during injection molding of a preform, and is advantageous over a cold parison type in that it can produce a variety of resin containers with excellent aesthetic appearance.

[0003] Preforms injection molded in injection molds can develop temperature unevenness that extends in the form of vertical stripes in the circumferential direction due to shear heating caused by branching or bending of the resin flow path in the hot runner. The location where this temperature unevenness appears in the preform varies for each individual injection mold, depending on the configuration of the resin flow path in the hot runner.

[0004] One method for reducing the temperature unevenness of the preform in hot parison blow molding is to use a temperature adjustment mold to adjust the temperature of the preform in the circumferential direction in a temperature adjustment step subsequent to the injection molding step. However, because the temperature adjustment step also aims to provide the preform with a temperature distribution suitable for blow molding, the temperature adjustment step may not be sufficient to reduce the temperature unevenness.

[0005] On the other hand, it has also been proposed to reduce the temperature unevenness in the injection molding process by changing the cooling strength in the circumferential direction of the injection molding die (injection core die) (for example, Patent Document 1).

[0006] Patent No. 3255485

[0007] However, with the configuration of Patent Document 1, the mold needs to be disassembled every time the cooling strength of the injection core mold is adjusted, making the adjustment of the cooling strength in the circumferential direction cumbersome. Also, the method of locally increasing the cooling strength in part of the circumferential direction of the injection core mold as in Patent Document 1 has limitations in terms of addressing the temperature unevenness.

[0008] Therefore, the present invention has been made in consideration of these problems, and aims to provide an injection molding mold that is more suitable for reducing circumferential temperature unevenness of a preform than conventional molds and that makes it easy to adjust the circumferential position of temperature adjustment points.

[0009] One aspect of the present invention is an injection molding die used for injection molding a bottomed, cylindrical resin preform. The injection molding die includes an injection cavity die that defines the outer peripheral shape of the preform and an injection core die that is inserted into the injection cavity die. The injection core die has a base that is attached to a fixed plate that drives the injection core die forward and backward and is rotatable in the circumferential direction relative to the fixed plate, and a mold body that is disposed at the tip of the base and defines the inner peripheral shape of the preform. The central axis of the mold body is eccentric with respect to the central axes of the injection cavity die and the base. Furthermore, the injection molding die is capable of adjusting the circumferential positions of a first portion, where the distance between the injection cavity die and the mold body is small, and a second portion, where the distance between the injection cavity die and the mold body is larger than the first portion, as the injection core die rotates.

[0010] According to one aspect of the present invention, it is possible to provide an injection molding die that is more suitable for reducing temperature unevenness in the circumferential direction of a preform than conventional die molds and that allows easy adjustment of the circumferential position of a temperature adjustment point.

[0011] 2A to 2D are diagrams showing a schematic configuration example of a blow molding apparatus according to the present embodiment; FIG. 2B is a diagram showing an example of an injection mold and a preform in an injection molding unit; (a) is a cross-sectional view taken along line A-A in FIG. 2, and (b) is a cross-sectional view taken along line B-B in FIG. 2; (a) to (d) are cross-sectional views taken along line C-C in FIG. 2; and FIG. 2C is a flowchart showing steps in a method for manufacturing a container.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, the same elements will be given the same reference numerals in the drawings. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown schematically and do not represent the actual shapes, dimensions, etc.

[0013] 1 is a diagram schematically illustrating an example of the configuration of a blow molding apparatus 10 according to this embodiment. The blow molding apparatus 10 is an example of an apparatus for manufacturing a resin container (hereinafter also simply referred to as a container), and employs a hot parison type (also referred to as a one-stage type) blow molding method in which a resin preform 1 is blow-molded into a container by utilizing the heat retained (internal heat) during injection molding without cooling it to room temperature.

[0014] The blow molding apparatus 10 includes an injection molding section 11, a temperature adjustment section 12, a blow molding section 13, a removal section 14, an injection device 15, and a conveying mechanism 16. The injection molding section 11, the temperature adjustment section 12, the blow molding section 13, and the removal section 14 are arranged at positions rotated by a predetermined angle (e.g., 90 degrees) around the conveying mechanism 16.

[0015] (Transport mechanism 16) The transport mechanism 16 includes a transfer plate 17 (not shown in FIG. 1) that moves in a rotational direction around an axis perpendicular to the plane of the paper in FIG. 1. The transfer plate 17 is composed of a single disk-shaped flat plate member or a plurality of roughly fan-shaped flat plate members divided into individual molding stations. On the transfer plate 17, one or more neck dies 18 (not shown in FIG. 1) that hold the neck portion 2 of the preform 1 (or the neck portion of the container) are arranged at predetermined angular intervals.

[0016] The transport mechanism 16 is equipped with a rotation mechanism (not shown) and moves the transfer plate 17 to transport the preform 1 (or container) with the neck portion 2 held by the neck mold 18, in the order of injection molding section 11, temperature adjustment section 12, blow molding section 13, and removal section 14. The preform 1 in the transport mechanism 16 is transported to each section in an upright position with the neck portion 2 positioned on the upper side and the longitudinal direction of the preform 1 aligned vertically. The transport mechanism 16 further includes an elevation mechanism (vertical mold opening / closing mechanism) and a mold opening mechanism for the neck mold 18, and is also capable of raising and lowering the transfer plate 17 and performing operations related to mold closing and mold opening (mold release) in the injection molding section 11, etc.

[0017] (Injection molding section 11) Figure 2 is a diagram showing an example of an injection molding die and preform 1 of the injection molding section 11. Figure 3(a) is a cross-sectional view taken along line A-A in Figure 2, and Figure 3(b) is a cross-sectional view taken along line B-B in Figure 2. Figures 4(a) to 4(d) correspond to cross-sectional views taken along line C-C in Figure 2.

[0018] The injection molding section 11 uses an injection mold to manufacture the preform 1. As shown in Figure 1, the injection molding section 11 is connected to an injection device 15 that supplies a resin material, which is a raw material for the preform 1.

[0019] 2, the overall shape of the preform 1 is a cylindrical shape with one end open and the other end closed at its bottom. The preform 1 has a neck portion 2 with an opening formed at one end, a body portion 3 connected to the neck portion 2 and formed into a cylindrical shape, and a bottom portion 4 connected to the body portion 3 and closing the other end.

[0020] Here, the material of the preform 1 and the container is a thermoplastic synthetic resin, and can be appropriately selected depending on the application of the container. Specific types of materials include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (polycyclohexanedimethylene terephthalate), Tritan (Tritan (registered trademark): a copolyester manufactured by Eastman Chemical Company, a polyester copolymer using cyclobutanediol as a monomer), copolyester, PP (polypropylene), PE (polyethylene), HDPE (high-density polyethylene), polyolefin, PC (polycarbonate), PES (polyethersulfone), PPSU (polyphenylsulfone), PS (polystyrene), COP / COC (cyclic olefin polymer), PMMA (polymethyl methacrylate: acrylic), PLA (polylactic acid), and biodegradable resin.

[0021] The injection molding section 11 includes an injection cavity mold 21, an injection core mold 22, and a hot runner mold (not shown) that guides molten resin supplied from the injection device 15 into the mold space. The injection cavity mold 21 and the injection core mold 22 are examples of injection molding dies.

[0022] The injection cavity mold 21 is a mold that defines the outer peripheral shape of the preform 1. The injection cavity mold 21 is placed above the hot runner mold and is fixed to a lower clamping plate (not shown) of the injection molding unit 11 together with the hot runner mold. A resin supply unit 23 of the hot runner mold is connected to the bottom of the mold space of the injection cavity mold 21. The injection cavity mold 21 has an internal flow path (not shown) through which a fluid (refrigerant or temperature control medium) flows, and is set to a temperature at which the outer surfaces of the body portion 3 and bottom portion 4 of the preform 1 solidify due to the fluid, for example, a temperature of 10°C to 80°C.

[0023] The injection core mold 22 is a mold that defines the shape of the inner periphery of the preform 1, and is fixed to a fixed plate 24 that is attached to the underside of an upper mold clamping plate (not shown) of the injection molding section 11. The fixed plate 24 holds at least one injection core mold 22. The injection core mold 22 is driven to move back and forth in the vertical direction together with the fixed plate 24 as the upper mold clamping plate is raised and lowered.

[0024] As shown in Figure 2, when the injection core mold 22 is lowered, it is inserted into the inner periphery of the injection cavity mold 21 from above the neck mold 18 of the transport mechanism 16. A mold space having a preform shape is formed by closing the injection cavity mold 21, injection core mold 22, and neck mold 18. Then, a resin material is injected from the injection device 15 via the resin supply unit 23 into the mold space having the preform shape, thereby producing the preform 1 in the injection molding unit 11.

[0025] The injection core mold 22 includes at least a base 25 and a mold body 26. The base 25 has an overall cylindrical shape and is disposed vertically in FIG. 2 . A flange-shaped protrusion 25a is formed on the base end side (upper side in FIG. 2 ) of the base 25, and a small-diameter portion 25b that is inserted into the neck mold 18 is formed on the tip end side (lower side in FIG. 2 ). The base 25 is inserted from above into an opening (through hole) of the fixed plate 24, and the protrusion 25a is engaged with a step in the opening of the fixed plate 24 to prevent it from coming loose. The base 25 is rotatable relative to the fixed plate 24 around a central axis along the longitudinal direction of the base 25. The injection core 22 (base 25 and mold body 26) also includes a flow path (not shown) through which a fluid (refrigerant or temperature-controlling medium) flows. The injection core 22 (base 25 and mold body 26) has a fluid flowing through a flow path via a fluid supply section and a fluid discharge section (not shown) provided on the fixed plate 24, and the temperature of the injection core mold 22 is set to the same temperature as the fluid. The temperature of the fluid is set to a temperature at which the inner surfaces of the body 3 and bottom 4 of the preform 1 solidify, for example, 10°C to 80°C.

[0026] 3(a), a plurality of recesses 27 are formed on the outer peripheral surface of the base 25 at positions that overlap with the fixing plate 24 in the axial direction, further toward the tip side than the protrusion. The plurality of recesses 27 all have the same shape and are arranged in a ring shape at predetermined intervals in the circumferential direction of the base 25. While FIG. 3(a) shows an example in which 12 recesses 27 are formed at intervals of 30° in the circumferential direction of the base 25, the number of recesses 27 on the base 25 is not limited to the above.

[0027] The recesses 27 can engage with stoppers 24a arranged at predetermined circumferential positions within the opening of the fixed plate 24. At least one stopper 24a is inserted into a through-hole (horizontal hole) that communicates with the opening provided in the side of the fixed plate 24 and fixed to the fixed plate 24. The stopper 24a is, for example, a ball plunger that allows a ball to advance and retreat radially through the opening. When the stopper 24a of the fixed plate 24 engages with any of the recesses 27 of the base 25, the base 25 is positioned relative to the fixed plate 24 at a predetermined rotation angle (every 30° in the example of FIG. 3( a)). Furthermore, when a torque greater than a certain level is applied to the injection core mold 22, the stopper 24a retracts radially outward, disengaging the stopper 24a from the recess 27. This allows the injection core mold 22 to rotate relative to the fixed plate 24.

[0028] 3(b), a plurality of adjustment holes (position adjustment portions) 28 for inserting a wrench (a position adjustment tool, not shown) are formed on the outer peripheral surface of the base 25. The wrench is, for example, a hexagonal wrench, and is an example of a tool used by an operator to rotate the injection core mold 22. When adjusting the circumferential position of the injection core mold 22, the operator can insert the wrench into one of the adjustment holes 28 and use the wrench to easily rotate the injection core mold 22 relative to the fixing plate 24.

[0029] The adjustment holes 28 are formed on the distal end side of the recessed portion 27 in the axial direction of the base 25, and are exposed to the outside of the fixing plate 24. The plurality of adjustment holes 28 all have the same shape, and are arranged in an annular shape at predetermined intervals in the circumferential direction of the base 25. Fig. 3(b) shows an example in which six adjustment holes 28 are formed in the circumferential direction of the base 25, but the number of adjustment holes 28 in the base 25 is not limited to the above.

[0030] The mold body 26 is provided on the tip side of the small diameter portion 25b of the base 25, and is the portion that is inserted into the injection cavity mold 21. The mold body 26 functions as a mold within the injection cavity mold 21 to define the inner peripheral shape of the preform 1.

[0031] Furthermore, the central axis of the base 25 coincides with the central axis O1 of the injection cavity mold 21, but the central axis O2 of the mold body 26 is radially offset from the central axis O1 of the injection cavity mold 21 and the central axis of the base 25. In other words, the mold body 26 is eccentric with respect to the injection cavity mold 21 and the base 25. Note that the amount of eccentricity between the central axis O2 of the mold body 26 and the central axis O1 of the base 25 or the injection cavity mold 21 (the difference in thickness between the first portion 31 and the second portion 32, which will be described later) is preferably set in the range of 0.05 mm to 0.15 mm.

[0032] Therefore, due to the eccentricity of the mold body 26, the radial distance between the injection cavity mold 21 and the mold body 26 is not uniform in the circumferential direction within the injection molding mold. The injection molding mold has a first region 31 where the mold body 26 is eccentrically positioned closer to the injection cavity mold 21 (the distance between the mold body 26 and the injection cavity mold 21 is small), and a second region 32 where the mold body 26 is eccentrically positioned farther from the injection cavity mold 21 (the distance between the mold body 26 and the injection cavity mold 21 is large). The first region 31 and the second region 32 face each other across the mold body 26 in the radial direction of the injection cavity mold 21. During injection molding of the preform 1, the wall thickness of the preform 1 in the first region 31 is thin, and the wall thickness of the preform 1 in the second region 32 is thicker than that in the first region 31. 4(a) to 4(d), by rotating the injection core mold 22 (held by the fixed plate 24) in the circumferential direction relative to the fixed plate 24, it is possible to change the eccentric position (eccentric direction) of the central axis O2 of the mold body 26 relative to the central axis O1 of the injection cavity mold 21, and thereby change the circumferential positions of the first portion 31 and the second portion 32 within the injection molding mold. The central axis of the opening of the fixed plate 24 is aligned on the same straight line as the central axis O1 of the injection cavity mold 21 and the central axis of the base 25.

[0033] It should be noted that even when the injection molding section 11 is opened, the neck mold 18 of the transport mechanism 16 does not open, but continues to hold and transport the preforms 1. The number of preforms 1 that are simultaneously molded in the injection molding section 11 (i.e., the number of containers that can be simultaneously molded by the blow molding apparatus 10) can be set as appropriate.

[0034] (Temperature Adjustment Unit 12) The temperature adjustment unit 12 includes a temperature adjustment mold (not shown), and cools (or heats) the preform 1, which is in a high temperature state after injection molding, by placing it in the temperature adjustment mold maintained at a predetermined temperature. The temperature adjustment unit 12 also has the function of adjusting the temperature distribution of the preform 1 to a predetermined state before transporting it to the blow molding unit 13.

[0035] The temperature adjustment mold of the temperature adjustment unit 12 has a temperature adjustment pot (or heating pot) that adjusts the temperature of the preform 1 from the outside, and a temperature adjustment rod (or heating rod) that adjusts the temperature of the preform 1 from the inside. The temperature adjustment mold may have an air introduction member that introduces compressed air for cooling into the preform 1 instead of the temperature adjustment rod.

[0036] (Blow molding unit 13) The blow molding unit 13 performs stretch blow molding on the preform 1 whose temperature has been adjusted in the temperature adjustment unit 12 to produce a container. The blow molding unit 13 includes a blow cavity mold, which is a pair of split molds corresponding to the shape of the container, a bottom mold, a stretch rod, and an air inlet / outlet member (blow core, none of which are shown). The blow molding unit 13 blow molds the preform 1 while stretching it. This allows the preform 1 to be shaped into the shape of the blow cavity mold to produce a container.

[0037] (Removal Section 14 ) The removal section 14 is configured to release the neck of the container manufactured in the blow molding section 13 from the neck mold 18 and remove the container to the outside of the blow molding apparatus 10 .

[0038] <Explanation of Container Manufacturing Method> Next, a container manufacturing method using the blow molding apparatus 10 of this embodiment will be described. Fig. 5 is a flowchart showing the steps of the container manufacturing method. In this embodiment, a mold adjustment step (S100) is performed before each step (S101 to S104) of the container manufacturing cycle, which will be described later, is performed.

[0039] (Step S100: Mold Adjustment Step) The mold adjustment step is a preparation step for adjusting the injection molding mold in accordance with vertical streak-like temperature irregularities in the preform 1 manufactured in the injection molding section 11.

[0040] First, the blow molding apparatus 10 is test-operated, and the operator identifies the position of a vertical streak-like high temperature portion that appears on the body portion 3 of the preform 1 before adjustment.

[0041] In a one-stage blow molding method, high-temperature portions of the preform 1 have a large amount of retained heat, making the preform 1 more susceptible to stretching. On the other hand, low-temperature portions of the preform 1 have less retained heat than high-temperature portions of the preform 1, making the preform 1 less susceptible to stretching. In other words, thin-walled portions of a blow-molded container correspond to high-temperature portions of the preform 1, and thick-walled portions of the container correspond to low-temperature portions of the preform 1. Therefore, it is possible to identify the positions of vertical streaks of high temperature that appear in the body portion 3 of the preform 1 from the wall thickness distribution of the blow-molded container.

[0042] Next, the worker adjusts the positions of the first portion 31 and the second portion 32 in the injection molding die in the circumferential direction to match the identified high-temperature portion of the preform 1. Specifically, the worker inserts a wrench (position adjustment tool) into the adjustment hole (position adjustment portion) 28 of the base 25 and uses the wrench to rotate the injection core die 22 in the circumferential direction until the first portion 31 overlaps the high-temperature portion of the preform 1. In other words, a rotation operation is performed to move the base 25 (held by the fixed plate) in the circumferential direction relative to the fixed plate 24, changing the eccentric position (eccentric direction) of the central axis O2 of the die body 26 with respect to the central axis O1 of the injection cavity die 21, so that the high-temperature portion of the preform 1 faces the first portion 31.

[0043] The above adjustment makes the thickness of the vertically streaked high-temperature areas in the body portion 3 of the preform 1 thinner than before the adjustment. When the wall thickness of the preform 1 is reduced, the heat retained in those areas decreases, making it difficult for the preform 1 to be stretched. Therefore, the above adjustment work can reduce the effects of temperature deviation in the vertically streaked high-temperature areas of the body portion 3. Once the above mold adjustment process is completed, the following steps of the container manufacturing cycle are carried out.

[0044] (Step S101: Injection Molding Process) First, in the injection molding section 11, resin is injected from the injection device 15 into a preform-shaped mold space formed by the injection cavity mold 21, the injection core mold 22, and the neck mold 18 of the transport mechanism 16, to manufacture the preform 1. Then, after the injection of the resin material (filling and pressure holding) is completed, or after a minimum cooling time set after the completion of the injection, the mold of the injection molding section 11 is opened.

[0045] Although not particularly limited, from the viewpoint of manufacturing a container with a high-speed molding cycle, it is preferable to open the mold in step S101 after completing the injection of the resin material (filling and pressure holding) without providing a cooling time for the preform 1 in the injection mold. On the other hand, when performing minimal cooling of the preform 1 in the injection mold, it is preferable that the time for cooling the resin material (cooling time) after completing the injection of the resin material in the injection molding section 11 is 1 / 2 or less of the time for injecting the resin material (injection time). Furthermore, the above cooling time can be made shorter than the time for injecting the resin material depending on the weight of the resin material. For example, the cooling time is more preferably 2 / 5 or less of the injection time of the resin material, even more preferably 1 / 4 or less, and particularly preferably 1 / 5 or less.

[0046] When the injection molding of the preform 1 is completed, the mold of the injection molding section 11 is opened and the preform 1 is released from the injection cavity mold 21 and the injection core mold 22. Next, the transfer plate 17 of the transport mechanism 16 moves so as to rotate by a predetermined angle, and the preform 1 held in the neck mold 18 is transported to the temperature adjustment section 12 in a state that includes the heat retained during injection molding.

[0047] (Step S102: Temperature Adjustment Step) Subsequently, in the temperature adjustment section 12, the preform 1 is housed in a temperature adjustment mold, and temperature adjustment is performed to bring the temperature of the preform 1 close to a temperature suitable for final blowing.

[0048] After the temperature adjustment step, the transfer plate 17 of the transport mechanism 16 moves so as to rotate by a predetermined angle, and the temperature-adjusted preform 1 held by the neck mold 18 is transported to the blow molding section 13.

[0049] (Step S103: Blow Molding Process) Next, in the blow molding section 13, blow molding of a container is performed. First, the blow cavity mold is closed to accommodate the preform 1 in the mold space, and an air inlet / outlet member (e.g., a blow core) is lowered to contact the neck portion 2 of the preform 1. Then, a stretching rod (vertical axis stretching member) is lowered to press the bottom portion 4 of the preform 1 from the inside, and while vertical axis stretching is performed as necessary, blow air is supplied from the air inlet / outlet member to stretch the preform 1 horizontally. As a result, the preform 1 is shaped by expanding so as to fit closely into the mold space of the blow cavity mold, and is blow-molded into a container. Note that the bottom mold waits at a lower position where it does not come into contact with the bottom portion 4 of the preform 1 before the blow cavity mold is closed, and is controlled to quickly rise to the molding position before or after mold closing.

[0050] (Step S104: Container Removal Process) When blow molding is completed, the blow cavity mold is opened. This allows the container to be removed from the blow molding section 13. Next, the transfer plate 17 of the conveying mechanism 16 moves a predetermined angle, and the container is transported to the removal section 14. In the removal section 14, the neck of the container is released from the neck mold 18, and the container is removed to the outside of the blow molding apparatus 10.

[0051] This completes one container manufacturing cycle in the container manufacturing method. Thereafter, the transfer plate 17 of the conveying mechanism 16 is moved a predetermined angle, and the above-described steps S101 to S104 are repeated. When the blow molding apparatus 10 is in operation, the production of four sets of containers is carried out in parallel, with each set having a time difference between each step. Due to the structure of the blow molding apparatus 10, the injection molding step, temperature adjustment step, blow molding step, and container removal step all take the same amount of time. Similarly, the transport time between each step is also the same amount of time.

[0052] The operation of this embodiment will be described below. The injection molding die of this embodiment includes an injection cavity die 21 that defines the outer peripheral shape of the preform 1, and an injection core die 22 that is inserted into the injection cavity die 21. The injection core die 22 has a base 25 that is attached to a fixed plate 24 that drives the injection core die 22 forward and backward and is rotatable in the circumferential direction relative to the fixed plate 24, and a mold body 26 that is disposed at the tip side of the base 25 and defines the inner peripheral shape of the preform 1. The central axis of the mold body 26 is eccentric with respect to the central axes of the injection cavity die 21 and the base 25. As the injection core die 22 rotates, the injection molding die is capable of adjusting the circumferential positions of a first portion 31, in which the distance between the injection cavity die 21 and the mold body 26 is small, and a second portion 32, in which the distance is larger than the first portion 31. According to the injection molding die of this embodiment, the thickness of the high-temperature portion in the circumferential direction of the preform 1 can be reduced by rotating the injection core die 22, thereby reducing the heat retained in the high-temperature portion. This reduces the temperature unevenness in the circumferential direction of the preform 1 immediately after injection molding. This improves the circumferential wall thickness distribution of the body portion in a container blow-molded from the preform 1. This also reduces the molding adjustment work in the temperature adjustment step of the preform 1. Furthermore, with the injection molding die of this embodiment, when adjusting temperature unevenness in the die adjustment step, it is sufficient to simply rotate the injection core die 22 without removing or disassembling the injection core die 22. Therefore, according to this embodiment, the workability when adjusting temperature unevenness in the die adjustment step is significantly improved, and the circumferential position adjustment of the temperature adjustment portion becomes easier.

[0053] Furthermore, in the injection molding die of this embodiment, the injection core die 22 is positioned circumferentially at predetermined intervals by the engagement between the recesses 27 and the stoppers 24a. This makes it easy to position the first portion 31 circumferentially during the die adjustment process. Furthermore, in the injection molding die of this embodiment, by attaching a wrench to the adjustment hole 28 of the base 25, a large torque can be applied to the injection core die 22, making it easy to rotate the injection core die 22 circumferentially. Furthermore, because the wrench is removable from the injection core die 22, the space required when arranging multiple injection core dies 22 in parallel can be reduced.

[0054] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0055] DESCRIPTION OF SYMBOLS 1...preform, 2...neck portion, 3...body portion, 4...bottom portion, 10...blow molding device, 11...injection molding section, 12...temperature adjustment section, 13...blow molding section, 14...removal section, 15...injection device, 16...conveying mechanism, 17...transfer plate, 18...neck mold, 21...injection cavity mold, 22...injection core mold, 23...resin supply section, 24...fixing plate, 24a...stopper, 25...base portion, 25a...projection portion, 25b...small diameter portion, 26...mold main body portion, 27...recess, 28...adjusting hole, 31...first portion, 32...second portion

Claims

1. An injection molding die used for injection molding of a bottomed cylindrical resin preform, comprising: an injection cavity die that determines the outer peripheral shape of the preform; and an injection core die that is inserted into the injection cavity die, wherein the injection core die has a base that is attached to a fixed plate that drives the injection core die back and forth and that can be rotated circumferentially relative to the fixed plate, and a mold body that is located at the tip of the base and determines the inner peripheral shape of the preform, the central axis of the mold body being eccentric with respect to the central axes of the injection cavity die and the base, and wherein the circumferential positions of a first portion where the gap between the injection cavity die and the mold body is small, and a second portion where the gap is larger than the first portion, are adjustable as the injection core die rotates.

2. An injection molding die as set forth in claim 1, wherein the base has a plurality of recesses at predetermined intervals in the circumferential direction that engage with stoppers provided on the fixing plate, and the injection core die is positioned in the circumferential direction by the engagement of the recesses with the stoppers.

3. The injection molding die according to claim 1, wherein the base has at least one position adjustment section for attaching a tool for the rotation operation at a position offset in the axial direction from the fixed plate.

4. A resin container manufacturing device comprising: an injection molding unit that injection molds a bottomed cylindrical resin preform; a temperature adjustment unit that adjusts the temperature of the injection molded preform; and a blow molding unit that blow molds the temperature-adjusted preform while it contains the heat retained during injection molding to manufacture a resin container, wherein the injection molding unit has an injection molding mold as defined in any one of claims 1 to 3.

5. A method for manufacturing a resin container, comprising: an injection molding step of injection molding a bottomed cylindrical resin preform; a temperature adjustment step of adjusting the temperature of the injection-molded preform; and a blow molding step of blow molding the temperature-adjusted preform while it contains the heat retained during injection molding, to manufacture a resin container, wherein in the injection molding step, an injection molding mold described in any one of claims 1 to 3 is used to form a high-temperature portion of the body of the preform in the circumferential direction into a thin-walled first portion.

6. A method for manufacturing a resin container as described in claim 5, further comprising a mold adjustment step of adjusting the circumferential position of the injection core mold so that the first portion corresponds to the high-temperature portion of the body portion, and wherein the injection molding step, the temperature adjustment step, and the blow molding step are carried out after the mold adjustment step.

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