Preform manufacturing device, manufacturing method, and mold for cooling

Abstract

This preform manufacturing device is provided with an injection molding part, a post-cooling part, and an extraction part. The post-cooling part has a first mold that accommodates a preform therein and contacts an outer surface of the preform, and a second mold that is inserted into the preform and provided with at least a cooling rod having a flow path for compressed air therein and a tip end piece attached to a tip end side of the cooling rod. The tip end piece includes a mold surface that corresponds to the shape of a bottom part of the preform and receives the bottom shape, and an opening part that is formed closer to a base end side than the mold surface and communicates with the flow path for compressed air. The post-cooling unit cools the bottom part with the bottom part of the preform pressed to the first mold by the mold surface of the tip end piece, and cools a barrel part with the barrel part of the preform pressed to the first mold by compressed air passing through the opening part.

Description

Preform manufacturing apparatus, manufacturing method, and cooling mold

[0001] The present invention relates to a preform manufacturing apparatus, a manufacturing method, and a cooling mold.

[0002] Conventionally, a rotary injection molding machine has been known that uses the vertical and circumferential movement of a transfer plate to sequentially transfer injection-molded resin preforms to a post-cooling section and an ejection section (see, for example, Patent Document 1).

[0003] In addition, in the blow molding of resin containers using the hot parison method, it has been proposed to shorten the cooling time of the preform in the injection mold and thereby shorten the molding cycle of the resin container (see, for example, Patent Document 2).

[0004] Japanese Patent Publication No. 7-8516 Patent No. 6505344

[0005] In the production of preforms, as in the case of blow molding of resin containers, efforts are being made to shorten the cooling time of the preforms in the injection mold in order to shorten the production cycle.

[0006] On the other hand, if the cooling time of the preform in the injection mold is shortened, the preform is released from the injection mold at a higher temperature than usual, which makes the preform more susceptible to shrinkage and deformation, resulting in a decrease in the dimensional accuracy of the preform and a defect in appearance (sink marks). Furthermore, because the preform released from the mold at a high temperature as described above is very soft, for example, if air is blown into the bottom of the preform during cooling, the bottom of the preform that the air hits may deform due to the air pressure, resulting in a decrease in dimensional accuracy.

[0007] Therefore, the present invention has been made in consideration of such problems, and aims to provide a preform manufacturing device that can suppress a decrease in the dimensional accuracy of preforms that are released from the injection molding section at high temperatures.

[0008] A preform manufacturing apparatus according to one aspect of the present invention includes an injection molding section that injection-moldes a bottomed, cylindrical resin preform using an injection mold, a post-cooling section that cools the preform manufactured in the injection molding section, and an ejection section that ejects the preform cooled in the post-cooling section to the outside of the apparatus. The post-cooling section includes a first mold that accommodates the preform and contacts the outer surface of the preform, and a second mold that is inserted into the preform and includes at least a cooling rod having an internal compressed air flow path and a tip piece attached to the tip of the cooling rod. The tip piece corresponds to the shape of the bottom of the preform and includes a mold surface that receives the bottom, and an opening formed proximal to the mold surface and communicating with the compressed air flow path. The post-cooling section cools the bottom of the preform while pressing the bottom against the first mold with the mold surface of the tip piece, and cools the body of the preform while pressing the body against the first mold with compressed air passing through the opening.

[0009] According to one aspect of the present invention, it is possible to provide a preform manufacturing apparatus that can suppress a decrease in the dimensional accuracy of a preform that is released from an injection molded section at a high temperature.

[0010] It is a diagram showing an example of the configuration of an injection molding apparatus according to the present embodiment. It is a diagram showing an example of the configuration of a post-cooling section of Figure 1. It is a perspective view showing a tip portion of a cooling rod of Figure 2. It is a diagram showing an example of the configuration of an extraction section of Figure 1. It is a flowchart showing the steps of a method for manufacturing a preform.

[0011] 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.

[0012] (Description of Injection Molding Apparatus) Fig. 1 is a diagram showing an example of the configuration of an injection molding apparatus 10 according to this embodiment. The injection molding apparatus 10 of this embodiment is a manufacturing apparatus used to manufacture a resin preform 1 at high speed.

[0013] The overall shape of the preform 1 is a cylindrical shape with one end open and the other end closed, as shown in Figures 2 and 4. The preform 1 includes a cylindrical body portion 3, a bottom portion 4 closing the other end of the body portion 3, and a neck portion 2 formed on the open side of one end of the body portion 3.

[0014] The injection molding apparatus 10 includes an injection molding section 11, a post-cooling section 12, a removal section 13, a transfer plate 14 as a conveying mechanism, and an injection device 15. The injection molding apparatus 10 further includes a machine base 10a, an upper base 10b, a lower base 10c, and an injection core mold movable platen 10d. The lower base 10c and the injection device 15 are arranged above the machine base 10a.

[0015] The upper base 10b is erected above the lower base 10c via a guide rod and is arranged so as to be able to move up and down in the vertical direction relative to the lower base 10c. The injection core mold movable platen 10d is erected above the upper base 10b via a guide rod and is arranged so as to be able to move up and down in the vertical direction relative to the upper base 10b. The transfer plate 14 is rotatably supported on the underside of the upper base 10b.

[0016] Above the upper base 10b, at a position corresponding to the post-cooling section 12, there is provided an elevator device for vertically moving a cooling rod 22 and a fitting core 23, which will be described later. Also, above the upper base 10b, at a position corresponding to the removal section 13, there is provided an elevator device for vertically moving a removal core 31, an air introduction pipe 32, and a mold opening cam, which will be described later.

[0017] Furthermore, through holes are formed in the upper base 10b and the transfer plate 14 at positions corresponding to the injection molding section 11, the post-cooling section 12, and the removal section 13. This allows an injection core mold (not shown), a cooling rod 22, a fitting core 23, a removal core 31, and an air introduction pipe 32 to approach or be inserted into the preform 1 and the neck mold 16. Furthermore, the injection molding apparatus 10 supports the neck portion 2 of the preform 1 with the neck mold 16 (described below), and intermittently transports the preform 1 to each molding section (each process), i.e., the injection molding section 11, the post-cooling section 12, and the removal section 13, while maintaining the neck portion 2 always facing upward.

[0018] The injection molding section 11, the post-cooling section 12, and the removal section 13 are disposed above the machine base 10a or the lower base 10c. With respect to the machine base 10a or the lower base 10c, the injection molding section 11, the post-cooling section 12, and the removal section 13 are disposed at positions rotated a predetermined angle (for example, 120 degrees) around the rotation center of the transfer plate 14.

[0019] (Transfer plate 14) The transfer plate 14 is composed of a single disk-shaped flat plate member or a plurality of roughly fan-shaped flat plate members divided for each molding station. On the underside of the transfer plate 14, a neck mold fixing plate 17 having a plurality of neck molds 16 for holding the neck portions 2 of the preforms 1 is provided, one or more at predetermined angles. The neck mold 16 is composed of a pair of neck split molds 16a. The neck mold fixing plate 17 is composed of a pair of split plates 17a that can be attached and detached. The neck split molds 16a are each fixed to the split plates 17a and open and close horizontally as the split plates 17a are attached and detached.

[0020] The transfer plate 14 is moved in a rotational direction by a conveying mechanism (not shown) equipped with a rotation mechanism (the transfer plate 14 rotates around the central axis (rotation axis) of the transfer plate 14), and conveys the preform 1, whose neck portion 2 is held by the neck mold 16 (or neck mold fixing plate 17), in this order to the injection molding section 11, the post-cooling section 12, and the removal section 13. The conveying mechanism further includes an elevation mechanism (vertical mold opening and closing mechanism), which performs operations to raise and lower the transfer plate 14 (or the upper base 10b that supports the transfer plate 14) and the injection core mold movable platen 10d, and also performs operations related to mold closing and mold opening (mold release) in the injection molding section 11, etc.

[0021] (Injection molding section 11) The injection molding section 11 includes an injection cavity mold 11a having a plurality of cavities and an injection core mold fixing plate 11b having a plurality of injection core molds (not shown), and manufactures the preform 1 by injection molding. An injection device 15 that supplies raw material (resin material) for the preform 1 is connected to the injection molding section 11.

[0022] In the injection molding section 11, the injection cavity mold 11a and the injection core mold are closed with the neck mold 16 of the transfer plate 14 to form a mold space in the shape of a preform. Then, a resin material is injected into this mold space from an injection device 15, whereby the preform 1 is manufactured in the injection molding section 11.

[0023] The material of the preform 1 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: copolyester), PP (polypropylene), PE (polyethylene), PC (polycarbonate), PES (polyethersulfone), PPUS (polyphenylsulfone), PS (polystyrene), COP / COC (cyclic olefin polymer), PMMA (polymethyl methacrylate: acrylic), and PLA (polylactic acid).

[0024] Furthermore, even when the injection molding section 11 is opened (the process of removing the preform 1 from the injection cavity mold 11a and removing the injection core mold from the preform 1), the neck mold 16 of the transfer plate 14 does not open (mold opening) but continues to hold and transport the preform 1. The number of preforms 1 molded simultaneously in the injection molding section 11 (the number N x M shown below) can be set appropriately. For example, if the number of rows (N) of neck mold fixing plates 17 is three and the number of neck molds fixed to one neck mold fixing plate 17 (M) is 16, the number of preforms 1 molded simultaneously in the injection molding section 11 will be 48.

[0025] (Post-cooling section 12 ) The post-cooling section 12 has the function of cooling the preforms 1 in a high temperature state that have been transported from the injection molding section 11 .

[0026] FIG. 2 is a diagram showing an example of the configuration of the post-cooling section 12. FIG. 2 partially shows the portion indicated by the symbol A in FIG. 1. The post-cooling section 12 includes a cooling cavity mold (cooling pot) 21, a cooling rod 22, and a fitting core (first core mold) 23 as a mold unit for cooling the preform 1. The cooling cavity mold 21 is an example of a first mold. The cooling rod 22, the fitting core 23, and a tip piece 25 described below are an example of a second mold. It is preferable that the number of cooling spaces, cooling rods 22, tip pieces 25, and fitting cores 23 described below in the cooling cavity mold 21 be the same as the number of preforms 1 molded at one time in the injection molding section 11.

[0027] The cooling cavity mold 21 is a mold having a cooling space (a space for accommodating the preform 1) of approximately the same shape as the preform 1 produced in the injection molding section 11. The cooling cavity mold 21 accommodates the preform 1 in its internal accommodation space and is in contact with the outer surface of the preform 1. A flow path (not shown) through which a temperature adjustment medium (refrigerant) flows is formed inside the cooling cavity mold 21. Therefore, the temperature of the cooling cavity mold 21 is maintained at a predetermined temperature by the temperature adjustment medium. The temperature of the temperature adjustment medium of the cooling cavity mold 21 is not particularly limited, but can be appropriately selected within a range of, for example, 5°C to 80°C.

[0028] The cooling rod 22 and the fitting core 23 are both hollow cylindrical bodies, and the cooling rod 22 is arranged concentrically inside the fitting core 23. The cooling rod 22 and the fitting core 23 are also inserted inside the neck mold 16 and the preform 1.

[0029] When inserted into the neck mold 16, the fitting core 23 has its tip in close contact with the inner periphery or upper end surface of the neck portion 2 of the preform 1, maintaining airtightness with the preform 1. An opening 23a for exhausting air from inside the preform 1 is formed at the tip of the fitting core 23. The space between the cooling rod 22 and the fitting core 23 forms an exhaust flow path connected to an air exhaust section (not shown).

[0030] The cooling rod 22 has a cylindrical main body 24, and a tip piece 25 is attached to the tip of the main body 24. The cooling rod 22 is inserted into the interior of the preform 1 up to a position where the tip piece 25 abuts against the bottom 4 of the preform 1. The interior of the main body 24 of the cooling rod 22 forms an air supply flow path that guides compressed air (air, gaseous refrigerant) from an air supply unit (not shown).

[0031] 3(a) and (b) are perspective views showing the tip portion of the cooling rod 22. The tip piece 25 of the cooling rod 22 is a mold component having a curved mold surface 25a at the tip end that corresponds to the shape of the inner periphery of the bottom portion 4 of the preform 1. Although not particularly limited, the tip piece 25 is preferably made of a material with high thermal conductivity, such as aluminum or an aluminum alloy.

[0032] The mold surface 25a of the tip piece 25 receives the bottom portion 4 of the preform 1 and presses the bottom portion 4 from the inside, thereby pressing the bottom portion 4 of the preform 1 against the inner surface of the cooling cavity mold 21. As a result, when the cooling rod 22 is inserted into the preform 1, the bottom portion 4 of the preform 1 is sandwiched between the mold surface 25a of the tip piece 25 and the cooling cavity mold 21.

[0033] 2, an air flow path 25b is formed within the tip piece 25, which communicates with the air supply flow path of the main body 24. The air flow path 25b of the tip piece 25 branches near the tip of the tip piece 25 and turns back toward the base end side of the tip piece 25 (the upper side in the figure, the side toward the barrel of the preform). The branched air flow paths 25b are arranged at equal intervals around the circumferential direction of the tip piece 25, and each communicates with an air outlet 25c (opening) formed on the base end side of the mold surface 25a of the tip piece 25. Each air outlet 25c is arranged so as to face the space between the preform 1 and the main body 24 of the cooling rod 22.

[0034] (Removal section 13) The removal section 13 is configured to release the neck section 2 of the preform 1 cooled in the post-cooling section 12 from the neck mold 16 and remove the preform 1 to the outside of the injection molding apparatus 10. Furthermore, the removal section 13 in this embodiment has an air injection function for cooling and removing the preform 1.

[0035] Fig. 4 is a diagram showing an example of the configuration of the ejection unit 13. Fig. 4 partially shows the portion indicated by the symbol B in Fig. 1. The ejection unit 13 includes an ejection core (second core mold) 31, an air introduction pipe 32, and a mold opening cam (not shown). The ejection core 31 and the air introduction pipe 32 are an example of an auxiliary cooling unit.

[0036] Both the take-out core 31 and the air inlet pipe 32 are hollow cylindrical bodies, and the air inlet pipe 32 is arranged concentrically inside the take-out core 31. The air inlet pipe 32 and the take-out core 31 are inserted inside the neck mold 16 and the preform 1.

[0037] When inserted into the neck mold 16, the tip of the removal core 31 is in close contact with the inner periphery or upper end surface of the neck portion 2 of the preform 1, maintaining airtightness with the preform 1. A ring-shaped airtight member 31b that abuts airtightly against the upper end surface of the neck portion 2 is provided at the tip of the removal core 31. The airtight member 31b may be omitted. An opening 31a is formed at the tip of the removal core 31 to exhaust air from inside the preform 1. The space between the air inlet pipe 32 and the removal core 31 forms an exhaust flow path connected to an air exhaust section (not shown).

[0038] The inside of the air introduction pipe 32 forms a flow path that introduces compressed air (air, gaseous refrigerant) from an air supply unit (not shown). An opening 32a is formed at the tip of the air introduction pipe 32 to introduce compressed air into the preform 1. The tip of the air introduction pipe 32 is inserted up to the vicinity of the bottom 4 of the preform 1.

[0039] Two sets of wedge-shaped mold-opening cams (not shown) operate independently of the take-out core 31 and the air inlet pipe 32 to separate the pair of neck split molds 16a in the closed state in a direction intersecting the axial direction of the preform 1. For example, the mold-opening cams are inserted into cam grooves (not shown) located at both ends of the pair of divided plates 17a in the closed state, or abut against cam followers (not shown) provided on the divided plates 17a instead of the cam grooves. This allows the neck mold 16 to be opened. The neck mold 16 is normally maintained in the closed state by being biased by a spring built into the pair of divided plates 17a (or the neck mold fixing plate 17). The number of take-out cores 31 and air inlet pipes 32 is preferably the same as the number of preforms 1 molded at one time in the injection molding section 11.

[0040] (Explanation of Preform Manufacturing Method) Next, a method for manufacturing the preform 1 using the injection molding apparatus 10 of this embodiment will be described. Fig. 5 is a flowchart showing the steps of the method for manufacturing the preform 1.

[0041] (Step S1: Injection Molding Process) In step S1, in the injection molding section 11, the injection core mold movable platen 10d and the transfer plate 14 (or upper base 10b) are lowered, and the outlet cavity mold, injection core mold, and neck mold 16 are closed. Then, resin is injected from the injection device 15 into the preform-shaped mold space formed by the mold closure, to produce the preform 1. Then, after a minimum cooling time provided after the injection of the resin material (filling and pressure holding) is completed, the injection mold (injection cavity mold and injection core mold) of the injection molding section 11 is opened.

[0042] Although not particularly limited, from the viewpoint of manufacturing the preform 1 in a high-speed molding cycle, it is preferable to open the injection mold in step S1 after the injection of the resin material (filling and pressure holding) is completed without providing a cooling time for the preform 1 in the injection mold (for example, the cooling time in the injection molding conditions set in the injection molding device 10 is set to 0 seconds). In the above case, the preform 1 is not cooled in the injection mold without pressure holding, so it is possible to prevent the preform 1 from shrinking during the cooling time and causing sink marks.

[0043] On the other hand, when minimal cooling of the preform 1 is performed within the injection mold, the time (cooling time) for cooling the resin material within the mold after the injection of the resin material is completed in the injection molding section 11 is preferably 1 / 2 or less of the time for injecting the resin material (injection time (including pressure holding time)). Furthermore, 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 (for example, the cooling time of the injection molding conditions set in the injection molding device 10 is set to 1 / 2 or less, 2 / 5 or less, 1 / 4 or less, or 1 / 5 or less of the injection time).

[0044] In step S1, the injection core mold movable platen 10d and the transfer plate 14 (or upper base 10b) are raised, and when the injection mold is opened, the preform 1 is released from the injection cavity mold and injection core mold at a high temperature that allows the preform 1 to maintain its outer shape. Next, the transfer plate 14 moves so as to rotate by a predetermined angle, and the preform 1 in a high-temperature state held in the neck mold 16 is transported to the post-cooling section 12.

[0045] (Step S2: Post-cooling step) Next, the preform 1 is cooled in the post-cooling section 12. In the post-cooling section 12, the high-temperature preform 1 is rapidly cooled, thereby suppressing whitening (clouding) due to spherulite generation crystallization that may occur when the preform 1 is slowly cooled.

[0046] In the post-cooling section 12, first, the transfer plate 14 (or upper base 10b) is lowered to accommodate the preform 1 in the accommodation space of the cooling cavity mold 21. Next, the cooling rod 22 and fitting core 23 are lowered from a first standby position where they do not interfere with the transfer plate 14 and inserted into the preform 1 accommodated in the cooling cavity mold 21. Here, the fitting core 23 comes into close contact with the neck portion 2 of the preform 1, maintaining an airtight state between the preform 1 and the fitting core 23.

[0047] The cooling rod 22 is inserted into the preform 1. The mold surface 25a at the tip of the tip piece 25 presses the bottom 4 of the preform 1 downward, forcing the bottom 4 of the preform 1 against the cooling cavity mold 21.

[0048] In the post-cooling section 12, the bottom 4 of the preform 1 is sandwiched between the tip piece 25 and the cooling cavity mold 21, and is in close contact with both molds. Therefore, in the post-cooling section 12, the bottom 4 of the preform 1 is cooled by heat exchange between the tip piece 25 on the inner surface side and the cooling cavity mold 21 on the outer surface side.

[0049] Furthermore, the tip piece 25 of the cooling rod 22 presses the bottom 4 of the preform 1 from the inside, thereby suppressing irregular shrinkage and deformation of the preform 1. Furthermore, the bottom 4 of the preform 1 is in close contact with the tip piece 25 and the cooling cavity mold 21, respectively, so that the bottom 4 of the preform 1 is maintained in a shape that follows the mold surface 25a of the tip piece 25 and the cooling cavity mold 21. This makes it possible to improve the shape accuracy (dimensional accuracy) of the bottom 4 of the preform 1.

[0050] Thereafter, a cooling blow is performed on the preform 1. In the cooling blow of this embodiment, compressed air is introduced into the preform 1 from the air outlet 25c via the flow path in the cooling rod 22 and the air flow path 25b of the tip piece 25, and the compressed air is exhausted from the opening 23a between the cooling rod 22 and the fitting core 23.

[0051] During the cooling blow, when compressed air is introduced into the preform 1 from the air outlet 25c of the tip piece 25, the body portion 3 of the preform 1 is pressed against the cooling cavity mold 21. Therefore, in the post-cooling section 12, the inner surface of the body portion 3 of the preform 1 is cooled by contact with the compressed air, and the outer surface is cooled by heat exchange with the cooling cavity mold 21. Furthermore, the body portion 3 of the preform 1 is maintained in a shape that follows the contour of the accommodation space of the cooling cavity mold 21.

[0052] Furthermore, the air outlet 25c of the tip piece 25 faces the space between the preform 1 and the main body 24 of the cooling rod 22, so the air outlet 25c is positioned so as not to face the inner surface of the preform 1. As a result, the compressed air ejected from the air outlet 25c does not directly hit the bottom 4 or body 3 of the preform 1. This prevents deformation such as localized depressions from occurring inside the preform 1 due to the pressure of the compressed air being ejected. As a result, the shape precision of the bottom 4 and body 3 of the preform 1 can be improved.

[0053] In this embodiment, compressed air is passed through the air flow path 25b of the tip piece 25, so it is easy to cool the tip piece 25, which receives heat from the bottom 4 of the preform 1. Therefore, even when manufacturing the preform 1 using a high-speed molding cycle, it is possible to prevent the tip piece 25 from becoming too hot, making it less likely that problems such as the preform 1 sticking to the tip piece 25 will occur.

[0054] When cooling of the preform 1 in the post-cooling section 12 is completed, the cooling rod 22 and fitting core 23 rise and separate from the preform 1, and then the transfer plate 14 (or upper base 10b) rises and the preform 1 is released from the cooling cavity mold 21. After the cooling rod 22 and fitting core 23 reach the first standby position, the transfer plate 14 then moves so as to rotate by a predetermined angle, and the preform 1 held in the neck mold 16 is transported to the removal section 13.

[0055] (Step S3: Removal Process) In the removal section 13, after the transfer plate 14 (or upper base 10b) has descended, the removal core 31 and air inlet pipe 32 are lowered from a second standby position where they do not interfere with the transfer plate 14, and are inserted into the preform 1 held in the neck mold 16. The removal core 31 comes into close contact with the neck 2 of the preform 1, maintaining an airtight seal between the preform 1 and the removal core 31. Compressed air is then introduced into the preform 1 from the opening 32a of the air inlet pipe 32, and the inside of the preform 1 is subjected to supplementary cooling. Although not particularly limited, the compressed air injection time and injection pressure for supplementary cooling in the removal section 13 may be set lower than those in the post-cooling section 12.

[0056] By performing auxiliary cooling of the preform 1 in the removal section 13, the temperature of the preform 1 can be brought closer to room temperature, and deformation and deterioration of dimensional accuracy due to thermal shrinkage of the preform 1 after removal can be more reliably suppressed. In the removal section 13, compressed air flows from the air inlet pipe 32 toward the bottom 4 of the preform 1, but because the preform 1 has already been cooled in the post-cooling section 12, there is almost no change in the shape of the bottom 4 of the preform 1 even when the compressed air hits it.

[0057] When the auxiliary cooling of the preform 1 in the removal section 13 is completed, the neck mold 16 is opened by the mold opening cam, as shown by the arrow in Figure 4. Thereafter, compressed air is injected from the air inlet pipe 32, which guides the preform 1 vertically and removes it from the neck mold 16, and the preform 1 is removed from the injection molding apparatus 10. Next, the removal core 31 and the air inlet pipe 32 rise to the second standby position.

[0058] This completes one cycle in the manufacturing method of the preform 1. Thereafter, the transfer plate 14 is moved by a predetermined angle, and the above steps S1 to S3 are repeated. When the injection molding apparatus 10 is in operation, the manufacture of three sets of preforms 1 is carried out in parallel, with a time difference between each step. Furthermore, due to the structure of the injection molding apparatus 10, the time for the injection molding step, post-cooling step, and removal step is all the same length. Similarly, the transport time between each step is also the same length.

[0059] The effects of this embodiment are described below. The post-cooling section 12 of the injection molding apparatus 10 of this embodiment includes a cooling cavity mold 21 that accommodates the preform 1 and contacts the outer surface of the preform, a cooling rod 22 that is inserted into the preform 1 and has a compressed air flow path therein, and a tip piece 25 that is attached to the tip of the cooling rod 22. The tip piece 25 corresponds to the shape of the bottom of the preform 1 and includes a mold surface 25a that receives the bottom 4, and an air outlet 25c that is formed more proximal than the mold surface 25a and communicates with the compressed air flow path. The post-cooling section 12 cools the bottom 4 of the preform 1 while the mold surface 25a of the tip piece 25 presses the bottom 4 against the cooling cavity mold 21, and cools the body 3 of the preform 1 while pressing the body 3 against the cooling cavity mold 21 with compressed air passing through the air outlet 25c.

[0060] In this embodiment, the bottom 4 of the preform 1 is cooled by heat exchange between the tip piece 25 on the inner surface side and the cooling cavity mold 21 on the outer surface side. Furthermore, by pressing the body 3 of the preform 1 against the cooling cavity mold 21 with compressed air passing through the air outlet 25c, the inner surface of the body 3 of the preform 1 is cooled by contact with the compressed air, and the outer surface side is cooled by heat exchange with the cooling cavity mold 21. Therefore, the preform 1 released at a high temperature from the injection molded part 11 can be cooled efficiently in a short time, and a decrease in the dimensional accuracy of the preform 1 due to thermal shrinkage can be suppressed.

[0061] In this embodiment, the tip piece 25 presses the bottom 4 of the preform 1, thereby suppressing irregular shrinkage and deformation of the preform 1 released from the mold at high temperature. Furthermore, the shape of the bottom 4 of the preform 1 can be maintained by pressing the tip piece 25 against the mold surface 25a and the cooling cavity mold 21 during cooling. Furthermore, by cooling the body portion 3 of the preform 1 while it is pressed against the cooling cavity mold 21 by compressed air passing through the air outlet 25c, the body portion 3 can be maintained in a shape that follows the shape of the cooling cavity mold 21. Therefore, the preform 1, which is easily deformed when released from the injection molded portion 11 at high temperature, is maintained in the desired shape during cooling, thereby improving the dimensional accuracy of the shape of the preform 1.

[0062] Furthermore, in this embodiment, by performing auxiliary cooling of the preform 1 in the removal section 13, deformation and deterioration of dimensional accuracy due to thermal shrinkage of the preform 1 after removal can be more reliably suppressed.

[0063] Furthermore, by cooling the preform 1 in the post-cooling section 12, the preform 1 can be released from the injection molding section 11 even when it is in a high temperature state, and the cooling time of the preform 1 in the injection molding section 11 can be significantly reduced. As a result, according to this embodiment, molding of the next preform 1 can be started earlier, and the molding cycle time of the preform 1 can be reduced.

[0064] Furthermore, the injection molding apparatus 10 supports the neck 2 of the preform 1 with the neck mold 16 from molding to removal, maintaining a state in which the neck 2 is always facing upward and the body 3 is always vertical. In other words, the preform 1 is not molded sideways in the injection molding section 11, and the preform 1 is not released from the neck mold 16 even when the preform 1 is transported or transferred. Here, preforms molded under conditions with short cooling times and released from the injection mold are soft except for the neck 2, and the body 3 and bottom 4 are easily deformed. For example, if the preform is injection molded sideways, the body 3 and bottom 4 will sag and bend under their own weight when released from the injection mold, preventing the preform 1 from being molded according to the standard or specifications. Furthermore, when the preform 1 is separated from the neck mold 16 and transported or transferred between the injection molding section 11 and the post-cooling section 12, the body section 3 and bottom section 4 become deformed due to vibrations or the like, making it impossible to accurately accommodate the preform 1 in the cooling cavity mold 21 of the post-cooling section 12 and therefore unable to properly cool it. As a result, bent or deformed marks remain on the cooled preform 1. With the injection molding apparatus 10 of this embodiment, deformation of the preform 1 when released from the injection mold or when transferred can be prevented, so the above-mentioned problems do not occur even when the molding cycle time is shortened.

[0065] The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

[0066] In the post-cooling section 12 of the above embodiment, an example has been described in which compressed air is introduced into the preform 1 from the air outlet 25c of the tip piece 25 and then exhausted from the opening 23a of the fitting core 23. However, it is also possible to introduce compressed air into the preform 1 from the opening 23a of the fitting core 23 and then exhaust the compressed air from the tip piece 25 side.

[0067] In the above embodiment, an example has been described in which compressed air is injected into the take-out section 13 to perform auxiliary cooling of the preform 1. However, the take-out section 13 may not be provided with a configuration for injecting compressed air, and the take-out section 13 may not perform auxiliary cooling of the preform 1.

[0068] In the above embodiment, an example has been described in which the neck mold 16 is opened and the preform is removed after auxiliary cooling of the preform 1 by injecting compressed air at the removal section 13. However, compressed air may be injected after opening the neck mold 16 at the removal section 13, thereby simultaneously performing auxiliary cooling and removing the preform 1.

[0069] Furthermore, 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 by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0070] DESCRIPTION OF SYMBOLS 1...preform, 2...neck portion, 3...body portion, 4...bottom portion, 10...injection molding apparatus, 11...injection molding section, 12...post-cooling section, 13...removal section, 14...transfer plate, 16...neck mold, 21...cooling cavity mold, 22...cooling rod, 23...fitting core, 25...tip piece, 25a...mold surface, 25b...air flow path, 25c...air outlet, 31...removal core, 32...air introduction pipe

Claims

1. an injection molding section that injection molds a bottomed cylindrical resin preform using an injection mold; A post-cooling section that cools the preform manufactured in the injection molding section; a removal section that removes the preform cooled in the post-cooling section to the outside of the apparatus, The post-cooling section includes: a first mold that accommodates the preform therein and is in contact with an outer surface of the preform; a second mold that is inserted into the preform and includes at least a cooling rod having a compressed air flow path therein and a tip piece that is attached to a tip side of the cooling rod; the tip piece includes a mold surface that corresponds to a shape of a bottom of the preform and receives the bottom, and an opening that is formed on a base end side of the mold surface and communicates with a flow path of the compressed air, The post-cooling section cools the bottom portion of the preform while the bottom portion is pressed against the first die by the die surface of the tip piece, and cools the body portion of the preform while the body portion is pressed against the first die by the compressed air passing through the opening. Preform manufacturing equipment.

2. The second mold further includes a cylindrical core mold that comes into contact with the neck portion of the preform. An apparatus for manufacturing the preform according to claim 1.

3. The compressed air in the post-cooling section is introduced from the opening toward the body of the preform. An apparatus for manufacturing the preform according to claim 1.

4. The ejection section has an auxiliary cooling section that introduces compressed air into the preform. An apparatus for manufacturing the preform according to claim 1.

5. The auxiliary cooling section introduces compressed air into the preform before the preform is released from a neck mold that holds the preform. An apparatus for manufacturing a preform according to claim 4.

6. In the injection molding section, the injection mold is opened after the filling of the resin material and the pressure holding are completed, and the preform after the filling and the pressure holding are completed is carried out without being cooled in the injection mold. An apparatus for manufacturing a preform according to any one of claims 1 to 5.

7. In the injection molding section, the time required to cool the resin material in the injection mold after the injection of the resin material is completed is ½ or less of the time required to inject the resin material into the injection mold. An apparatus for manufacturing a preform according to any one of claims 1 to 5.

8. an injection molding step of injection molding a bottomed cylindrical resin preform using an injection mold; a post-cooling step of cooling the preform produced in the injection molding step; and a removal step of removing the preform cooled in the post-cooling step to the outside. In the post-cooling step, a first mold that accommodates the preform therein and is in contact with an outer surface of the preform; a second mold including at least a cooling rod having a compressed air flow path therein and a tip piece attached to a tip side of the cooling rod, the tip piece includes a mold surface that corresponds to a shape of a bottom of the preform and receives the bottom, and an opening that is formed on a base end side of the mold surface and communicates with a flow path of the compressed air, In the post-cooling step, the bottom portion of the preform is cooled while the bottom portion is pressed against the first die by the die surface of the tip piece, and the body portion of the preform is cooled while the body portion is pressed against the first die by the compressed air passing through the opening. A method for manufacturing a preform.

9. A cooling mold used in a post-cooling section of a preform manufacturing apparatus including an injection molding section that injection molds a bottomed cylindrical resin preform using an injection mold, a post-cooling section that cools the preform manufactured in the injection molding section, and a removal section that removes the preform cooled in the post-cooling section to the outside of the apparatus, The cooling mold is a first mold that accommodates the preform therein and is in contact with an outer surface of the preform; a second mold that is inserted into the preform and includes at least a cooling rod having a compressed air flow path therein and a tip piece that is attached to a tip side of the cooling rod; The tip piece includes a mold surface that corresponds to the shape of the bottom of the preform and receives the bottom, and an opening that is formed on the base end side of the mold surface and communicates with the flow path of the compressed air. Cooling mold.