Preform manufacturing equipment, manufacturing method, and cooling mold

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

Technical Field

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

Background Art

[0002] Conventionally, a rotary injection molding machine that sequentially transfers an injection-molded resin preform to a post-cooling unit and a take-out unit by using the vertical movement and circumferential movement of a transfer plate is known (see, for example, Patent Document 1).

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding the production of preforms, as in the case of blow molding of resin containers, shortening the cooling time of the preforms in the injection mold has been considered from the viewpoint of shortening the production cycle.

[0006] On the other hand, shortening the cooling time of the preform in the injection mold causes the preform to be released from the mold at a higher temperature than usual, making it more susceptible to shrinkage and deformation. As a result, the dimensional accuracy of the preform decreases and surface defects (sink marks) are more likely to occur. Furthermore, because the preform released at high temperatures as described above is very soft, if air is blown into the bottom of the preform during cooling, for example, the bottom of the preform exposed to the air pressure may deform, potentially reducing its dimensional accuracy.

[0007] Therefore, the present invention has been made in view of these problems, and aims to provide a preform manufacturing apparatus that can suppress the decrease in dimensional accuracy of preforms that have been demolded at high temperature from the injection molding section. [Means for solving the problem]

[0008] A preform manufacturing apparatus according to one aspect of the present invention comprises an injection molding section for injection molding a bottomed cylindrical resin preform with an injection mold, a post-cooling section for cooling the preform manufactured in the injection molding section, and a removal section for removing the preform cooled in the post-cooling section to the outside of the apparatus. The post-cooling section comprises a first mold that houses the preform inside and is in contact with the outer surface of the preform, and a second mold that is inserted into the preform and comprises at least a cooling rod having a compressed air passage inside and a tip piece attached to the tip side of the cooling rod. The tip piece corresponds to the bottom shape of the preform and includes a mold surface that receives the bottom, and an opening formed on the base end side of the mold surface and communicating with the compressed air passage. The post-cooling section cools the bottom of the preform by pressing the bottom of the preform against the first mold with the mold surface of the tip piece, and cools the body of the preform by pressing the body of the preform against the first mold with compressed air passing through the opening. [Effects of the Invention]

[0009] According to one aspect of the present invention, a preform manufacturing apparatus can be provided that can suppress the decrease in dimensional accuracy of preforms released from an injection molding section at high temperatures. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of the configuration of an injection molding apparatus according to this embodiment. [Figure 2] This figure shows an example of the configuration of the rear cooling section shown in Figure 1. [Figure 3] Figure 2 is a perspective view showing the tip of the cooling rod. [Figure 4] This figure shows an example of the configuration of the extraction section in Figure 1. [Figure 5] This is a flowchart showing the steps involved in the manufacturing process of preforms. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In the embodiments, for the sake of clarity, structures and elements other than the main parts of the present invention will be simplified or omitted in the description. Also, the same elements will be denoted by the same reference numerals in the drawings. Note that the shapes and dimensions of each element shown in the drawings are schematic representations and do not represent the actual shapes and dimensions.

[0012] (Description of injection molding equipment) Figure 1 shows an example of the configuration of the injection molding apparatus 10 according to this embodiment. The injection molding apparatus 10 of this embodiment is a manufacturing apparatus used to manufacture resin preforms 1 at high speed.

[0013] The overall shape of the preform 1 is a bottomed cylindrical shape with one end open and the other end closed, as shown in Figures 2 and 4 below. The preform 1 comprises a cylindrical body 3, a bottom 4 that closes the other end of the body 3, and a neck 2 formed on the open end of the body 3.

[0014] The injection molding apparatus 10 comprises an injection molding section 11, a post-cooling section 12, an extraction section 13, a transfer plate 14 as a transport mechanism, and an injection device 15. Furthermore, the injection molding apparatus 10 comprises a machine base 10a, an upper base 10b, a lower base 10c, and an injection core type movable platen 10d. The lower base 10c and the injection device 15 are positioned above the machine base 10a.

[0015] The upper base 10b is erected above the lower base 10c via guide rods and is positioned to move vertically relative to the lower base 10c. The injection core type movable platen 10d is erected above the upper base 10b via guide rods and is positioned to move vertically relative to the upper base 10b. The transfer plate 14 is rotatably supported on the lower surface of the upper base 10b.

[0016] Furthermore, above the upper base plate 10b, at a position corresponding to the rear cooling section 12, a lifting device is provided to move the cooling rod 22 and the fitting core 23, which will be described later, up and down. Also, above the upper base plate 10b, at a position corresponding to the removal section 13, a lifting device is provided to move the removal core 31, the air introduction pipe 32, and the mold opening cam, which will be described later, up and down.

[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 the injection core mold (not shown), cooling rod 22, fitting core 23, removal core 31, and air introduction pipe 32 to approach or be inserted into the preform 1 and the neck mold 16. The injection molding apparatus 10 also supports the neck portion 2 of the preform 1 with the neck mold 16 (described later), maintaining the neck portion 2 in an upward position at all times, and intermittently transports it to each molding section (each process) of the injection molding section 11, the post-cooling section 12, and the removal section 13.

[0018] The injection molding section 11, the post-cooling section 12, and the take-out section 13 are arranged 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 take-out section 13 are arranged at positions rotated by a predetermined angle (for example, 120 degrees) with respect to 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 substantially fan-shaped flat plate members divided for each molding station. On the lower surface side of the transfer plate 14, a neck mold fixing plate 17 having a plurality of neck molds 16 for holding the neck portion 2 of the preform 1 is provided one or more at each predetermined angle. 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 separable split plates 17a. The neck split mold 16a is fixed to each of the split plates 17a and opens and closes in the horizontal direction as the split plates 17a separate and contact.

[0020] The transfer plate 14 is moved in the rotational direction by a transfer mechanism (not shown) having a rotation mechanism (the transfer plate 14 rotates with respect to the central axis (rotation axis) of the transfer plate 14), and conveys the preform 1 with the neck portion 2 held by the neck mold 16 (or the neck mold fixing plate 17) in the order of the injection molding section 11, the post-cooling section 12, and the take-out section 13. Incidentally, the above transfer mechanism further includes a lifting mechanism (vertical mold opening and closing mechanism), and performs an operation of lifting the transfer plate 14 (or the upper base 10b supporting the transfer plate) and the injection core mold movable disk 10d, and also performs operations related to mold closing and mold opening (ejection) in the injection molding section 11 and the like.

[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 for supplying the raw material (resin material) of the preform 1 is connected to the injection molding section 11.

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

[0023] The material of Preform 1 described above is a thermoplastic synthetic resin, which can be appropriately selected depending on the application of the container. Specific examples of materials include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (polycyclohexanedimethylene terephthalate), 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 unit 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 on the transfer plate 14 remains open (opens) and continues to hold and transport the preform 1. The number of preforms 1 that are simultaneously molded in the injection molding unit 11 (the number N × M shown below) can be set as appropriate. For example, if the number of rows (N) of the neck mold fixing plate 17 is set to 3, and the number of neck molds (M) fixed to one neck mold fixing plate 17 is set to 16, then the number of preforms 1 that are simultaneously molded in the injection molding unit 11 will be 48.

[0025] (Post-cooling section 12) The post-cooling unit 12 is responsible for cooling the high-temperature preform 1 that has been transported from the injection molding unit 11.

[0026] Figure 2 shows an example of the configuration of the post-cooling unit 12. In Figure 2, the part indicated by the reference numeral A in Figure 1 is partially shown. The post-cooling unit 12, as a mold unit for cooling the preform 1, comprises a cooling cavity mold (cooling pot) 21, a cooling rod 22, and a fitting core (first core mold) 23. The cooling cavity mold 21 is an example of a first mold. The cooling rod 22, fitting core 23, and the tip piece 25 described later are examples of a second mold. It is preferable that the number of cooling spaces in the cooling cavity mold 21, the cooling rods 22, the tip piece 25, and the fitting core 23 is the same as the number of preforms 1 molded at one time in the injection molding unit 11.

[0027] The cooling cavity mold 21 is a mold having a cooling space (a space for housing the preform 1) that is substantially the same shape as the preform 1 manufactured in the injection molding section 11. The cooling cavity mold 21 houses the preform 1 in its inner housing space and is in contact with the outer surface of the preform 1. A flow path (not shown) for the temperature control medium (refrigerant) 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 control medium. The temperature of the temperature control medium in the cooling cavity type 21 is not particularly limited, but can be appropriately selected within a range of, for example, 5°C to 80°C.

[0028] Both the cooling rod 22 and the mating core 23 are hollow cylindrical bodies, with the cooling rod 22 concentrically positioned inside the mating core 23. Furthermore, the cooling rod 22 and the mating core 23 are inserted inside the neck mold 16 and the preform 1.

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

[0030] The cooling rod 22 has a cylindrical body portion 24, and a tip piece 25 is attached to the tip of the body portion 24. The cooling rod 22 is inserted into the preform 1 until the tip piece 25 contacts the bottom portion 4 of the preform 1. The inside of the body portion 24 of the cooling rod 22 also forms an air supply passage for introducing compressed air (air, gaseous refrigerant) from an air supply unit (not shown).

[0031] Figures 3(a) and 3(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 its tip that corresponds to the inner circumference shape 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 4 of the preform 1 and presses the bottom 4 from the inside, pressing the bottom 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 4 of the preform 1 is sandwiched between the mold surface 25a of the tip piece 25 and the cooling cavity mold 21.

[0033] Furthermore, as shown in Figure 2, an air passage 25b is formed inside the tip piece 25, which communicates with the air supply passage of the main body 24. The air passage 25b of the tip piece 25 branches near the tip of the tip piece 25 and folds back toward the base end side of the tip piece 25 (upper side in the figure, the body side of the preform). The multiple branched air passages 25b are arranged at equal intervals in 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 positioned 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 portion 2 of the preform 1, which has been cooled in the post-cooling section 12, from the neck mold 16, and to remove the preform 1 to the outside of the injection molding apparatus 10. In addition, the removal section 13 in this embodiment has an air injection function for cooling and removing the preform 1.

[0035] Figure 4 shows an example of the configuration of the extraction unit 13. In Figure 4, the part indicated by the reference numeral B in Figure 1 is partially shown. The extraction unit 13 comprises an extraction core (second core mold) 31, an air introduction pipe 32, and a mold opening cam (not shown). The extraction core 31 and the air introduction pipe 32 are examples of auxiliary cooling units.

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

[0037] When the extraction core 31 is inserted into the neck mold 16, its tip is in close contact with the inner circumference or upper end surface of the neck portion 2 of the preform 1, maintaining airtightness with the preform 1. The tip of the extraction core 31 is provided with a ring-shaped airtight member 31b that airtightly abuts against the upper end surface of the neck portion 2. The airtight member 31b may be omitted. An opening 31a for exhausting air from inside the preform 1 is formed at the tip of the extraction core 31. The space between the air introduction pipe 32 and the extraction core 31 constitutes 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 for introducing compressed air (air, gaseous refrigerant) from the air supply unit (not shown). An opening 32a is formed at the tip of the air introduction pipe 32 for introducing compressed air into the preform 1. The tip of the air introduction pipe 32 is also inserted near the bottom 4 of the preform 1.

[0039] Furthermore, two sets of wedge-shaped mold-opening cams (not shown) operate independently of the removal core 31 and the air introduction pipe 32, separating a pair of neck split molds 16a that are in a 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 a pair of split plates 17a that are in a closed state, or they contact cam followers (not shown) provided on the split plates 17a instead of cam grooves. This allows the neck mold 16 to be opened. The neck mold 16 is normally maintained in a closed state by being biased by springs built into the pair of split plates 17a (or neck mold fixing plate 17). Preferably, the number of removal cores 31 and air introduction pipes 32 is the same as the number of preforms 1 that are molded at one time in the injection molding unit 11.

[0040] (Explanation of preform manufacturing method) Next, the method for manufacturing the preform 1 using the injection molding apparatus 10 of this embodiment will be described. Figure 5 is a flowchart showing the steps of the manufacturing method for 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. Shooting The ejection cavity mold, injection core mold, and neck mold 16 are closed. Then, resin is injected from the injection device 15 into the mold space of the preform shape formed by the mold closing, and the preform 1 is manufactured. After a minimum cooling time provided after the injection (filling and holding pressure) of the resin material is completed, the injection molds (injection cavity mold and injection core mold) of the injection molding section 11 are opened.

[0042] While not particularly limited, from the viewpoint of manufacturing preform 1 in a high-speed molding cycle, it is preferable to open the mold in step S1 without allowing a cooling time for the preform 1 in the injection mold after the completion of injection (filling and holding pressure) of the resin material (for example, the cooling time in the injection molding conditions set in the injection molding apparatus 10 is set to 0 seconds). In the above case, since the preform 1 is not cooled in the injection mold without holding pressure, the phenomenon of shrinkage and sink marks occurring due to shrinkage of the preform 1 during the cooling time can be suppressed.

[0043] On the other hand, when performing minimal cooling of the preform 1 within the injection mold, the time for cooling the resin material within the mold after the injection of the resin material in the injection molding unit 11 is completed (cooling time) is preferably 1 / 2 or less of the time for injecting the resin material (injection time (including holding pressure 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 apparatus 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 temperature high enough to maintain its outer shape. Next, the transfer plate 14 moves to rotate by a predetermined angle, and the high-temperature preform 1 held in the neck mold 16 is transported to the post-cooling section 12.

[0045] (Step S2: Post-cooling process) 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, which suppresses whitening (clouding) due to spherulite formation and crystallization that may occur when the preform 1 is cooled slowly.

[0046] In the post-cooling section 12, first, the preform 1 is housed in the housing space of the cooling cavity mold 21 by the descent of the transfer plate 14 (or upper base 10b). Subsequently, the cooling rod 22 and the fitting core 23 are lowered from a first standby position that does not interfere with the transfer plate 14 and inserted into the preform 1 housed in the cooling cavity mold 21. At this point, the fitting core 23 is in close contact with the neck portion 2 of the preform 1, and an airtight seal is maintained between the preform 1 and the fitting core 23.

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

[0049] Furthermore, the tip piece 25 of the cooling rod 22 presses against the bottom 4 of the preform 1 from the inside, suppressing irregular shrinkage deformation of the preform 1. In addition, the bottom 4 of the preform 1 is held 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 conforms to the mold surface 25a of the tip piece 25 and the cooling cavity mold 21. This improves the shape accuracy (dimensional accuracy) of the bottom 4 of the preform 1.

[0050] Subsequently, the preform 1 is subjected to a cooling blow. In this embodiment, compressed air is introduced into the preform 1 from the air outlet 25c via the air passage in the cooling rod 22 and the air passage 25b of the tip piece 25, and the compressed air is exhausted from the opening 23a between the cooling rod 22 and the fitted 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 3 of the preform 1 is pressed against the cooling cavity mold 21. Therefore, in the post-cooling section 12, the body 3 of the preform 1 is cooled on its inner surface by contact with the compressed air, and on its outer surface by heat exchange with the cooling cavity mold 21. In addition, the body 3 of the preform 1 is maintained in a shape that conforms to the contour of the housing space of the cooling cavity mold 21.

[0052] Furthermore, since 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, the air outlet 25c is positioned so as not to face the inner surface of the preform 1. Therefore, the compressed air ejected from the air outlet 25c does not directly hit the bottom 4 or body 3 of the preform 1. Consequently, it is possible to suppress the occurrence of localized deformations such as depressions on the inside of the preform 1 due to the pressure when compressed air is ejected. As a result, the shape accuracy of the bottom 4 and body 3 of the preform 1 can be improved.

[0053] In this embodiment, compressed air is flowed through the air passage 25b of the tip piece 25, making it 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 in a high-speed molding cycle, the temperature of the tip piece 25 can be suppressed, and problems such as the preform 1 sticking to the tip piece 25 are less likely to occur.

[0054] Once the cooling of the preform 1 in the post-cooling section 12 is complete, the cooling rods 22 and the mating core 23 rise and detach from the preform 1, and then the transfer plate 14 (or upper substrate 10b) rises and the preform 1 is released from the cooling cavity mold 21. After the cooling rods 22 and the mating core 23 reach the first standby position, the transfer plate 14 then moves 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 extraction section 13, after the transfer plate 14 (or upper base plate 10b) descends, the extraction core 31 and air introduction pipe 32 descend from a second standby position where they do not interfere with the transfer plate 14 and are inserted into the preform 1 held by the neck type 16. The extraction core 31 is in close contact with the neck portion 2 of the preform 1, and an airtight seal is maintained between the preform 1 and the extraction core 31. Subsequently, compressed air is introduced into the preform 1 from the opening 32a of the air introduction pipe 32, and the inside of the preform 1 is supplementarily cooled. Although not particularly limited, the injection time and injection pressure of compressed air for the supplementary cooling in the extraction section 13 may be set lower than those of 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, thereby more reliably suppressing deformation due to thermal shrinkage of the preform 1 after removal and a decrease in dimensional accuracy. In the removal section 13, compressed air flows from the air introduction pipe 32 toward the bottom 4 of the preform 1, but since 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] Once the auxiliary cooling of the preform 1 in the removal section 13 is complete, the mold opening cam opens the neck mold 16, as shown by the arrow in Figure 4. Then, compressed air is injected from the air introduction pipe 32 to guide the preform 1 vertically, causing it to detach 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 introduction pipe 32 rise to a second standby position.

[0058] This completes one cycle in the manufacturing method of preform 1. Subsequently, by moving the transfer plate 14 by a predetermined angle, each of the steps S1 to S3 described above is repeated. When the injection molding apparatus 10 is in operation, the manufacturing of three sets of preform 1, each with a time difference between each step, is performed in parallel. Furthermore, due to the structure of the injection molding apparatus 10, the injection molding process, the post-cooling process, and the removal process all take the same amount of time. Similarly, the transport time between each process is also the same amount of time.

[0059] The effects and advantages of this embodiment will be described below. The post-cooling section 12 of the injection molding apparatus 10 in this embodiment includes a cooling cavity mold 21 that houses the preform 1 inside and contacts the outer surface of the preform, a cooling rod 22 inserted into the preform 1 and having a compressed air passage inside, and a tip piece 25 attached to the tip side of the cooling rod 22. The tip piece 25 corresponds to the bottom shape of the preform 1 and includes a mold surface 25a that receives the bottom 4, and an air outlet 25c formed on the base end side of the mold surface 25a and communicating with the compressed air passage. The post-cooling section 12 cools the bottom 4 of the preform 1 by pressing it against the cooling cavity mold 21 with the mold surface 25a of the tip piece 25, and cools the body 3 of the preform 1 by pressing it against the cooling cavity mold 21 with compressed air passing through the air outlet 25c.

[0060] In this embodiment, the bottom portion 4 of the preform 1 is cooled by heat exchange between the inner tip piece 25 and the outer cooling cavity mold 21. Furthermore, by pressing the body portion 3 of the preform 1 against the cooling cavity mold 21 with compressed air passing through the air outlet 25c, the body portion 3 of the preform 1 is cooled on its inner side by contact with the compressed air, and on its outer side by heat exchange with the cooling cavity mold 21. Therefore, the preform 1, which has been demolded from the injection molding section 11 at a high temperature, can be cooled efficiently in a short time, and the 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 against the bottom 4 of the preform 1, suppressing irregular shrinkage deformation of the preform 1 after high-temperature demolding. 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. In addition, by cooling the body 3 of the preform 1 with compressed air passing through the air outlet 25c while it is pressed against the cooling cavity mold 21, the body 3 can be maintained in a shape that conforms to the cooling cavity mold 21. Therefore, since the preform 1, which is prone to deformation after being demolded at high temperature from the injection molding unit 11, is maintained in the desired shape during cooling, the dimensional accuracy of the shape of the preform 1 can be improved.

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

[0063] Furthermore, by cooling the preform 1 in the post-cooling section 12, the injection molding section 11 can release the preform 1 even at a high temperature, significantly reducing the cooling time of the preform 1 in the injection molding section 11. As a result, according to this embodiment, the molding of the next preform 1 can be started earlier, thus shortening the molding cycle time of the preform 1.

[0064] Furthermore, the injection molding apparatus 10 supports the neck portion 2 of the preform 1 with the neck mold 16 from molding to removal, maintaining a state in which the neck portion 2 is always facing upward and the body portion 3 is always in a vertical direction. In other words, the injection molding section 11 does not mold the preform 1 in a horizontal position, and the preform 1 is not released from the neck mold 16 during transport and transfer of the preform 1. Here, a preform molded under conditions of short cooling time and released from the injection mold is soft except for the neck portion 2, and the body portion 3 and bottom portion 4 are easily deformed. For example, when a preform is injection molded horizontally, the body portion 3 and bottom portion 4 sag and bend under their own weight when released from the injection mold, making it impossible to mold a preform 1 that conforms to the standard or specifications. Also, when the preform 1 is transported and transferred between the injection molding section 11 and the post-cooling section 12 after being separated from the neck mold 16, the body portion 3 and bottom portion 4 deform due to vibration, etc., making it impossible to accurately position the preform 1 in the cooling cavity mold 21 of the post-cooling section 12, and thus it cannot be properly cooled. As a result, the preform 1 after cooling is left with bent or deformed marks. With the injection molding apparatus 10 of this embodiment, deformation of the preform 1 during demolding and transfer from the injection mold can be suppressed, so the above-mentioned problems do not occur even if the molding cycle time is shortened.

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

[0066] In the above embodiment, the post-cooling section 12 was described in which compressed air is introduced into the preform 1 from the air outlet 25c of the tip piece 25 and the compressed air is 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 exhaust the compressed air from the tip piece 25 side.

[0067] Furthermore, in the above embodiment, an example was described in which compressed air is injected into the extraction section 13 to provide auxiliary cooling of the preform 1. However, the extraction section 13 may not be configured to inject compressed air, and auxiliary cooling of the preform 1 may not be performed in the extraction section 13.

[0068] Furthermore, in the above embodiment, an example was described in which the preform 1 is cooled by spraying compressed air in the removal section 13, and then the neck mold 16 is opened to remove the preform. However, compressed air may be sprayed after opening the neck mold 16 in the removal section 13 to simultaneously cool and remove the preform 1.

[0069] Furthermore, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0070] 1…Preform, 2…Neck section, 3…Body section, 4…Bottom section, 10…Injection molding machine, 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…Matching core, 25…Tip piece, 25a…Mold surface, 25b…Air passage, 25c…Air outlet, 31…Removal core, 32…Air introduction pipe

Claims

1. An injection molding section in which a bottomed cylindrical resin preform is injection molded using an injection die, A post-cooling section for cooling the preform manufactured in the injection molding section, The apparatus includes an outlet for removing the preform, which has been cooled in the aforementioned post-cooling section, from the outside of the apparatus. The aforementioned post-cooling unit is A first mold that houses the preform inside and contacts the outer surface of the preform, A second mold is provided, which is inserted into the preform and comprises at least a cooling rod having a compressed air passage inside, and a tip piece attached to the tip of the cooling rod, The tip piece corresponds to the bottom shape of the preform and includes a mold surface that receives the bottom and an opening formed on the base end side of the mold surface that communicates with the compressed air passage. The rear cooling unit cools the bottom of the preform while pressing it against the first mold with the mold surface of the tip piece, and cools the body of the preform while pressing it against the first mold with the compressed air passing through the opening. Preform manufacturing equipment.

2. The second mold further comprises a cylindrical core mold that contacts the neck portion of the preform. The apparatus for manufacturing a 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. The apparatus for manufacturing a preform according to claim 1.

4. The extraction unit has an auxiliary cooling unit that introduces compressed air into the preform. The apparatus for manufacturing a preform according to claim 1.

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

6. In the injection molding section, after the filling and holding pressure of the resin material is completed, the injection mold is opened and the preform is removed from the injection mold without cooling after the filling and holding pressure is completed. A preform manufacturing apparatus according to any one of claims 1 to 5.

7. In the injection molding section, the time for cooling the resin material in the injection mold after the injection of the resin material is completed is 1 / 2 or less of the time for injecting the resin material into the injection mold. A preform manufacturing apparatus according to any one of claims 1 to 5.

8. The injection molding process involves injection molding a bottomed cylindrical resin preform using an injection mold, A post-cooling step for cooling the preform manufactured in the injection molding step, The process includes a removal step for removing the preform that has been cooled in the post-cooling step from the outside, In the aforementioned post-cooling step, A first mold that houses the preform inside and contacts the outer surface of the preform, A second mold is applied, which is inserted into the preform and comprises at least a cooling rod having a compressed air passage inside, and a tip piece attached to the tip of the cooling rod. The tip piece corresponds to the bottom shape of the preform and includes a mold surface that receives the bottom and an opening formed on the base end side of the mold surface that communicates with the compressed air passage. In the post-cooling step described above, the bottom of the preform is cooled while the bottom of the preform is pressed against the first mold with the mold surface of the tip piece, and the body of the preform is cooled while the body of the preform is pressed against the first mold with the compressed air passing through the opening. A method for manufacturing preforms.

9. A cooling mold applied to the post-cooling section of a preform manufacturing apparatus, comprising: an injection molding section for injection molding a bottomed cylindrical resin preform with an injection mold; a post-cooling section for cooling the preform manufactured in the injection molding section; and a removal section for removing the preform cooled in the post-cooling section to the outside of the apparatus, The cooling mold is, A first mold that houses the preform inside and contacts the outer surface of the preform, A second mold is provided, which is inserted into the preform and comprises at least a cooling rod having a compressed air passage inside, and a tip piece attached to the tip of the cooling rod, The tip piece corresponds to the bottom shape of the preform and includes a mold surface that receives the bottom and an opening formed on the base end side of the mold surface that communicates with the compressed air passage. Cooling mold.

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