Preform manufacturing device, manufacturing method, and cooling mold

Abstract

This preform manufacturing device is provided with an injection molding unit, a post-cooling unit, and an extraction unit. The post-cooling unit is provided with: a first mold which accommodates the preform on the inside thereof and which is in contact with the outer surface of the preform; and a second mold inserted into the preform, the second mold being provided with at least a cooling rod having a flow path for compressed air therein, and a tip attached to the tip side of the cooling rod. The front end piece comprises a die surface which corresponds to the shape of the bottom of the preform and receives the bottom; and an opening part which is formed closer to the base end side than the die surface and communicates with a flow path for compressed air. The post-cooling unit cools the bottom of the preform in a state in which the bottom is pressed against the first mold by the mold surface of the tip, and cools the main body of the preform in a state in which the main body is pressed against the first mold by the compressed air passing through the opening.

Description

Technical Field

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

[0002] Conventionally, there is known a rotary injection molding machine that sequentially transfers injection-molded resin preforms to a post-cooling section and a removal section by vertical and circumferential movement of a transfer plate (see, for example, Patent Document 1).

[0003] In the blow molding of resin containers 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).

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Publication No. 7-8516

[0007] Patent Document 2: Japanese Patent No. 6505344 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] Regarding the production of preforms, similarly to the case of blow molding of resin containers, shortening the cooling time of the preforms in the injection mold has been studied from the viewpoint of shortening the production cycle.

[0010] On the other hand, if the cooling time of the preform in the injection mold is shortened, the preform is demolded from the injection mold at a higher temperature than usual, so the preform is easily shrunk and deformed, and as a result, the dimensional accuracy of the preform is reduced and the appearance is poor (sink marks) is easily generated. In addition, the preform demolded at a high temperature as described above is very soft, so, for example, if air is blown into the bottom of the preform during cooling, the bottom of the preform contacted by the air may also be deformed by the air pressure, resulting in reduced dimensional accuracy.

[0011] Therefore, the present invention has been made in view of such a problem, and an object of the present invention is to provide a preform manufacturing apparatus capable of suppressing a decrease in dimensional accuracy of a preform released from an injection molded part at a high temperature.

[0012] Technical solutions for solving technical problems

[0013] A preform manufacturing device according to one embodiment of the present invention includes: 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 by the injection molding section; and a take-out section that takes out the preform cooled by the post-cooling section to the outside of the device. The post-cooling section includes: a first mold that accommodates the preform inside and contacts the outer surface of the preform; and a second mold that is inserted into the preform, the second mold including at least a cooling rod having a compressed air flow path inside and a front end member attached to the front end side of the cooling rod. The front end member 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 closer to the base end side than the mold surface and communicates with the compressed air flow path. The post-cooling section cools the bottom of the preform while the bottom of the preform is pressed against the first mold by the mold surface of the front end member, and cools the main body of the preform while the main body of the preform is pressed against the first mold by the compressed air passing through the opening.

[0014] Effects of the Invention

[0015] According to one aspect of the present invention, it is possible to provide a preform manufacturing apparatus capable of suppressing a decrease in dimensional accuracy of a preform released from an injection molded portion at a high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram showing a configuration example of an injection molding device according to the present embodiment.

[0017] Figure 2 Yes means Figure 1 A diagram showing an example of the structure of a post-cooling unit.

[0018] Figure 3 Yes means Figure 2 A perspective view of the front end portion of the cooling rod.

[0019] Figure 4 Yes means Figure 1 A diagram showing a structural example of a removal portion.

[0020] Figure 5 This is a flowchart showing the steps of a method for manufacturing a preform. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0022] In the embodiments, in order to make the description easy to understand, the structures and elements other than the main parts of the present invention are simplified or omitted for description. In addition, in the drawings, the same reference numerals are marked for the same elements. It should be noted that the shapes, sizes, etc. of the elements shown in the drawings are schematic representations and do not represent the actual shapes, sizes, etc.

[0023] (Description of injection molding device)

[0024] Figure 1 1 is a diagram showing a configuration example of an injection molding device 10 according to the present embodiment. The injection molding device 10 according to the present embodiment is a manufacturing device used for manufacturing a preform 1 made of resin at high speed.

[0025] It should be noted that the overall shape of the preform 1 is as described below. Figure 2 , Figure 4 The preform 1 has a cylindrical body 3 formed in a cylindrical shape, a bottom 4 closing the other end of the body 3 , and a neck 2 formed on the open side of one end of the body 3 .

[0026] The injection molding device 10 includes an injection molding unit 11, a post-cooling unit 12, a take-out unit 13, a transfer plate 14 as a conveying mechanism, and an injection device 15. The injection molding device 10 includes a machine table 10a, an upper base plate 10b, a lower base plate 10c, and an injection core mold movable plate 10d. The lower base plate 10c and the injection device 15 are arranged on the upper side of the machine table 10a.

[0027] The upper base 10b is erected above the lower base 10c via guide rods and is configured to be able to rise and fall in the vertical direction relative to the lower base 10c. The injection core mold movable plate 10d is erected above the upper base 10b via guide rods and is configured to be able to rise and fall in the vertical direction relative to the upper base 10b. The transfer plate 14 is rotatably supported on the lower surface of the upper base 10b.

[0028] It should be noted that a lifting device for moving the cooling rod 22 and the fitting core 23 described below up and down is provided at a position above the upper base 10b corresponding to the post-cooling section 12. In addition, a lifting device for moving the removal core 31, the air introduction pipe 32, and the mold opening cam described below up and down is provided at a position above the upper base 10b corresponding to the removal section 13.

[0029] In addition, through holes are formed in the upper base plate 10b and the transfer plate 14 at positions corresponding to the injection molding section 11, the post-cooling section 12, and the take-out section 13. Thus, the injection core mold (not shown), the cooling rod 22, the fitting core 23, the take-out core 31, and the air introduction tube 32 can approach or be inserted into the preform 1 and the neck mold 16. In addition, the injection molding device 10 supports the neck 2 of the preform 1 by using the neck mold 16 (described later), maintains the neck 2 always facing upward, and intermittently conveys it to each molding section (each process) of the injection molding section 11, the post-cooling section 12, and the take-out section 13.

[0030] The injection molding unit 11, the post-cooling unit 12, and the take-out unit 13 are arranged on the upper side of the machine table 10a or the lower base plate 10c. The injection molding unit 11, the post-cooling unit 12, and the take-out unit 13 are arranged at positions rotated by a given angle (e.g., 120 degrees) relative to the rotation center of the transfer plate 14 with respect to the machine table 10a or the lower base plate 10c.

[0031] (Transfer plate 14)

[0032] 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 lower surface side of the transfer plate 14, one or more neck mold fixing plates 17 are provided at given angles, and the neck mold fixing plate 17 has a plurality of neck molds 16 for holding the neck 2 of the preform 1. The neck mold 16 is composed of a pair of neck parting molds 16a. The neck mold fixing plate 17 is composed of a pair of partition plates 17a that can be separated and contacted. The neck parting molds 16a are respectively fixed to the partition plates 17a, and open and close in the horizontal direction as the partition plates 17a separate and contact.

[0033] The transfer plate 14 is moved in the rotation direction by a conveying mechanism (not shown) having a rotation mechanism (the transfer plate 14 rotates with the central axis (rotation axis) of the transfer plate 14 as a reference), and the preform 1 with the neck 2 held by the neck mold 16 (or the neck mold fixing plate 17) is conveyed in the order of the injection molding section 11, the post-cooling section 12, and the removal section 13. It should be noted that the above-mentioned conveying mechanism also has a lifting mechanism (vertical mold opening and closing mechanism), which performs the operation of lifting and lowering the transfer plate 14 (or the upper base plate 10b supporting the transfer plate 14) and the injection core mold movable plate 10d, and also performs the operations related to mold closing and mold opening (mold removal) in the injection molding section 11, etc.

[0034] (Injection molding section 11)

[0035] The injection molding unit 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). The injection molding unit 11 manufactures the preform 1 by injection molding. The injection molding unit 11 is connected to an injection device 15 for supplying a raw material (resin material) of the preform 1.

[0036] In the injection molding unit 11, the injection cavity mold 11a, the injection core mold, and the neck mold 16 of the transfer plate 14 are closed to form a mold space in the shape of a preform. Then, the preform 1 is manufactured by the injection molding unit 11 by injecting resin material into the mold space from the injection device 15.

[0037] The material of the preform 1 is a thermoplastic synthetic resin, which can be appropriately selected according to the purpose of the container. Specific types 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 acid), PLA (polylactic acid), etc.

[0038] It should be noted that when the injection molding section 11 is opened (a process of pulling the preform 1 out of the injection cavity mold 11a and the injection core mold out of the preform 1), the neck mold 16 of the transfer plate 14 is not opened (opened) but still holds and conveys the preform 1. The number of preforms 1 molded simultaneously by the injection molding section 11 (the number of N×M shown below) can be appropriately set. For example, when the number of rows (N) of the neck mold fixing plates 17 is set to 3 and the number of neck molds (M) fixed to one neck mold fixing plate 17 is set to 16, the number of preforms 1 molded simultaneously by the injection molding section 11 is 48.

[0039] (After cooling unit 12)

[0040] The post-cooling section 12 has a function of cooling the high-temperature preform 1 conveyed from the injection molding section 11 .

[0041] Figure 2 1 is a diagram showing a configuration example of the aftercooling unit 12. Figure 2 In, locally Figure 1 The portion indicated by the reference numeral A in the figure. The rear cooling section 12 includes a cooling cavity mold (cooling tank) 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. In addition, the cooling rod 22, the fitting core 23, and the front end part 25 described later are an example of a second mold. It should be noted that the number of the cooling space, cooling rod 22, front end part 25, and fitting core 23 described later of the cooling cavity mold 21 is preferably the same as the number of preforms 1 molded at one time in the injection molding section 11.

[0042] The cooling cavity mold 21 is a mold having a cooling space (accommodation space for the preform 1) having a shape substantially the same as the shape of the preform 1 manufactured by the injection molding unit 11. The cooling cavity mold 21 accommodates the preform 1 in the accommodation space inside and contacts the outer surface of the preform 1. A flow path (not shown) for the flow of a temperature adjustment medium (refrigerant) is formed inside the cooling cavity mold 21. Therefore, the temperature of the cooling cavity mold 21 is maintained at a given temperature by the temperature adjustment medium.

[0043] It should be noted that the temperature of the temperature regulating medium for cooling the cavity mold 21 is not particularly limited, and can be appropriately selected within the range of, for example, 5° C. to 80° C.

[0044] The cooling rod 22 and the fitting core 23 are both hollow cylindrical bodies, and the cooling rod 22 is concentrically arranged inside the fitting core 23. The cooling rod 22 and the fitting core 23 are inserted inside the neck mold 16 and the preform 1.

[0045] When the fitting core 23 is inserted into the neck mold 16, its front end is in close contact with the inner periphery or upper end surface of the neck 2 of the preform 1 to maintain airtightness with the preform 1. In addition, an opening 23a for exhausting air from the preform 1 is formed at the front end of the fitting core 23. In addition, the space between the cooling rod 22 and the fitting core 23 constitutes a flow path for exhaust connected to an air exhaust unit (not shown).

[0046] The cooling rod 22 has a cylindrical main body 24, and a front end member 25 is installed at the front end of the main body 24. The cooling rod 22 is inserted into the interior of the preform 1 until the front end member 25 abuts against the bottom 4 of the preform 1. In addition, the interior of the main body 24 of the cooling rod 22 constitutes a flow path for guiding compressed air (air, gaseous refrigerant) from an air supply unit (not shown).

[0047] Figure 3 (a) and (b) are three-dimensional views showing the front end portion of the cooling rod 22. The front end member 25 of the cooling rod 22 is a mold member having a curved mold surface 25a on the front end side, and the curved mold surface 25a corresponds to the inner peripheral shape of the bottom 4 of the preform 1. Although not particularly limited, the front end member 25 is preferably formed of a material with high thermal conductivity, such as aluminum or aluminum alloy.

[0048] The die surface 25a of the front end member 25 has the following functions: receiving the bottom 4 of the preform 1 and pressing the bottom 4 from the inside, and pressing the bottom 4 of the preform 1 against the inner surface of the cooling cavity mold 21. Therefore, when the cooling rod 22 is inserted into the preform 1, the bottom 4 of the preform 1 is clamped by the die surface 25a of the front end member 25 and the cooling cavity mold 21.

[0049] In addition, if Figure 2As shown, an air flow path 25b connected to the air supply flow path of the main body 24 is formed in the front end part 25. The air flow path 25b of the front end part 25 branches near the front end of the front end part 25 and turns back toward the base end side of the front end part 25 (the upper side in the figure, the main body side of the preform). The multiple branched air flow paths 25b are arranged at equal intervals in the circumferential direction of the front end part 25, and are respectively connected to the air outlets 25c (openings) formed on the base end side of the front end part 25 relative to the mold surface 25a. Each air outlet 25c is configured to face the space between the preform 1 and the main body 24 of the cooling rod 22.

[0050] (Taking out section 13)

[0051] The take-out section 13 is configured to open the neck 2 of the preform 1 cooled by the post-cooling section 12 from the neck mold 16 and take the preform 1 out of the injection molding apparatus 10. The take-out section 13 in this embodiment has an air jetting function for cooling and taking out the preform 1.

[0052] Figure 4 1 is a diagram showing a structural example of the take-out portion 13. Figure 4 In, locally Figure 1 The extraction part 13 includes 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 an auxiliary cooling part.

[0053] The extraction core 31 and the air introduction tube 32 are both hollow cylindrical bodies, and the air introduction tube 32 is concentrically arranged inside the extraction core 31. The air introduction tube 32 and the extraction core 31 are inserted into the inside of the neck mold 16 and the preform 1.

[0054] When the removal core 31 is inserted into the neck mold 16, its front end is in close contact with the inner circumference or upper end surface of the neck 2 of the preform 1 to maintain airtightness with the preform 1. An annular airtight component 31b is provided at the front end of the removal core 31 so as to be airtightly abutted against the upper end surface of the neck 2. The airtight component 31b may also be omitted. In addition, an opening 31a for discharging air from the preform 1 is formed at the front end of the removal core 31. In addition, the space between the air inlet pipe 32 and the removal core 31 constitutes an exhaust flow path connected to an air exhaust portion (not shown).

[0055] The interior of the air introduction pipe 32 constitutes a flow path for guiding compressed air (air, gaseous refrigerant) from an air supply unit (not shown). An opening 32a for introducing compressed air into the preform 1 is formed at the front end of the air introduction pipe 32. In addition, the front end of the air introduction pipe 32 is inserted until it reaches the vicinity of the bottom 4 of the preform 1.

[0056] In addition, two sets of mold opening cams (not shown) with wedge-shaped front ends independently operate relative to the removal core 31 and the air introduction tube 32, so that the pair of neck portion molds 16a in the closed state are separated in the direction intersecting the axial direction of the preform 1. For example, the mold opening cam is inserted into the cam grooves (not shown) located at both ends of the pair of partition plates 17a in the closed state, or abuts against the cam followers (not shown) provided on the partition plates 17a instead of the cam grooves. In this way, the neck mold 16 can be opened. It should be noted that the neck mold 16 is normally maintained in a closed state by the springs built into the pair of partition plates 17a (or the neck mold fixing plate 17). It should be noted that the number of the removal core 31 and the air introduction tube 32 is preferably the same as the number of the preforms 1 molded at one time in the injection molding section 11.

[0057] (Description of the method for producing the preform)

[0058] Next, a method for manufacturing the preform 1 using the injection molding apparatus 10 of the present embodiment will be described. Figure 5 It is a flowchart showing the steps of the method for manufacturing the preform 1 .

[0059] (Step S1: Injection Molding Process)

[0060] In step S1, in the injection molding unit 11, the injection core mold movable plate 10d and the transfer plate 14 (or the upper base plate 10b) are lowered, and the shot cavity mold, the injection core mold, and the 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 closed mold to manufacture the preform 1. Then, after the injection (filling and holding pressure) of the resin material is completed and the minimum cooling time is set, the injection mold (injection cavity mold and injection core mold) of the injection molding unit 11 is opened.

[0061] Although not particularly limited, from the viewpoint of manufacturing the preform 1 at a high-speed molding cycle, it is preferred that in step S1, after the injection (filling and holding pressure) of the resin material is completed, the mold is opened without providing a cooling time for the preform 1 in the injection mold (for example, the cooling time of the injection molding condition set for the injection molding device 10 is set to 0 seconds). In the above case, the preform 1 is not cooled in the state where there is no holding pressure in the injection mold, so it is also possible to suppress the phenomenon that the preform 1 shrinks during the cooling time and forms a sink mark.

[0062] On the other hand, when the preform 1 is cooled to a minimum in the injection mold, it is preferred that the time for cooling the resin material in the mold after the injection molding unit 11 completes the injection of the resin material (cooling time) is 1 / 2 or less relative to the time for injecting the resin material (injection time (including holding time)). In addition, the cooling time is more preferably 2 / 5 or less, further preferably 1 / 4 or less, and particularly preferably 1 / 5 or less relative to the injection time of the resin material (for example, the cooling time of the injection molding conditions set for the injection molding device 10 is set to any one of 1 / 2 or less, 2 / 5 or less, 1 / 4 or less, and 1 / 5 or less of the injection time).

[0063] In step S1, the injection core mold movable plate 10d and the transfer plate 14 (or the upper base plate 10b) are raised, and when the injection mold is opened, the preform 1 is demolded from the injection cavity mold and the injection core mold at a high temperature to a degree that the outer shape can be maintained. Next, the transfer plate 14 is moved in a manner of rotating by a given angle, and the preform 1 maintained at a high temperature in the neck mold 16 is transported to the post-cooling unit 12.

[0064] (Step S2: Post-cooling process)

[0065] Next, the preform 1 is cooled in the post-cooling section 12. Since the high-temperature preform 1 is rapidly cooled in the post-cooling section 12, whitening (cloudiness) due to spherulite crystallization that may occur when the preform 1 is slowly cooled can be suppressed.

[0066] In the post-cooling section 12, first, the preform 1 is accommodated in the accommodation space of the cooling cavity mold 21 by the lowering of the transfer plate 14 (or the upper base plate 10b). Then, the cooling rod 22 and the fitting core 23 are lowered from the first standby position that does 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 is closely fitted with the neck 2 of the preform 1, and an airtight state is maintained between the preform 1 and the fitting core 23.

[0067] In addition, the cooling rod 22 is inserted into the preform 1. The mold surface 25a at the front end of the front end member 25 presses the bottom 4 of the preform 1 downward, and presses the bottom 4 of the preform 1 against the cooling cavity mold 21.

[0068] The bottom 4 of the preform 1 in the rear cooling section 12 is clamped by the front end member 25 and the cooling cavity mold 21, and is in a state of being closely fitted with the two molds. Therefore, in the rear cooling section 12, the bottom 4 of the preform 1 is cooled by heat exchange between the front end member 25 on the inner surface side and the cooling cavity mold 21 on the outer surface side.

[0069] In addition, the front end member 25 of the cooling rod 22 presses the bottom 4 of the preform 1 from the inside, thereby suppressing irregular shrinkage deformation of the preform 1. Furthermore, the bottom 4 of the preform 1 is kept in the shape of the mold surface 25a of the front end member 25 and the cooling cavity mold 21 by the bottom 4 of the preform 1 being in close contact with the front end member 25 and the cooling cavity mold 21, respectively. Thus, the shape accuracy (dimensional accuracy) of the bottom 4 of the preform 1 can be improved.

[0070] After that, a cooling blow is performed on the preform 1. In the cooling blow of the present 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 front end member 25, and the compressed air is discharged from the opening 23a between the cooling rod 22 and the interlocking core 23.

[0071] During the cooling air supply, if compressed air is introduced into the preform 1 from the air outlet 25c of the front end member 25, the main body 3 of the preform 1 is pressed against the cooling cavity mold 21. Therefore, in the post-cooling section 12, the inner surface side of the main 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. In addition, the main body 3 of the preform 1 is maintained in a shape that follows the contour of the accommodating space of the cooling cavity mold 21.

[0072] In addition, since the air outlet 25c of the front end member 25 faces the space between the preform 1 and the main body 24 of the cooling rod 22, the air outlet 25c is arranged not to face the inner surface of the preform 1. Therefore, the compressed air ejected from the air outlet 25c does not directly contact the bottom 4 and the main body 3 of the preform 1. Therefore, it is possible to suppress deformation such as local dents on the inner side of the preform 1 due to the pressure when the compressed air is ejected. As a result, the shape accuracy of the bottom 4 and the main body 3 of the preform 1 can be improved.

[0073] It should be noted that in the present embodiment, since compressed air is caused to flow through the air flow path 25b of the front end member 25, it is easy to cool the front end member 25 that receives heat from the bottom portion 4 of the preform 1. Therefore, even when the preform 1 is manufactured at a high-speed molding cycle, it is possible to suppress the temperature of the front end member 25, and, for example, it is less likely to cause an undesirable situation such as the preform 1 sticking to the front end member 25.

[0074] When the cooling of the preform 1 in the post-cooling section 12 is completed, the cooling rod 22 and the fitting core 23 rise and separate from the preform 1, and then the transfer plate 14 (or the upper base plate 10b) rises to release the preform 1 from the cooling cavity mold 21. After the cooling rod 22 and the fitting core 23 reach the first standby position, the transfer plate 14 then moves in a manner of rotating a given angle to transport the preform 1 held in the neck mold 16 to the removal section 13.

[0075] (Step S3: Removal process)

[0076] In the take-out section 13, after the transfer plate 14 (or the upper base plate 10b) is lowered, the take-out core 31 and the air introduction tube 32 are lowered from the second standby position that does not interfere with the transfer plate 14, and are inserted into the preform 1 held in the neck mold 16. The take-out core 31 is in close contact with the neck 2 of the preform 1, and an airtight state is maintained between the preform 1 and the take-out core 31. After that, compressed air is introduced into the preform 1 from the opening 32a of the air introduction tube 32, and the inside of the preform 1 is auxiliary cooled. Although not particularly limited, the injection time and injection pressure of the compressed air in the auxiliary cooling of the take-out section 13 can also be set lower than those of the post-cooling section 12.

[0077] By performing auxiliary cooling of the preform 1 in the take-out section 13, the temperature of the preform 1 can be brought closer to room temperature, and deformation and reduction in dimensional accuracy caused by thermal shrinkage of the taken-out preform 1 can be more reliably suppressed. It should be noted that in the take-out 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 been cooled in the post-cooling section 12, the shape of the bottom 4 of the preform 1 is hardly changed even if it contacts the compressed air.

[0078] When the auxiliary cooling of the preform 1 in the take-out section 13 is completed, Figure 4 As shown by the middle arrow, the neck mold 16 is opened by the mold opening cam. Then, by ejecting compressed air from the air introduction pipe 32, the preform 1 is guided in the vertical direction and separated from the neck mold 16, and the preform 1 is taken out of the injection molding device 10. Next, the removal core 31 and the air introduction pipe 32 are raised to the second standby position.

[0079] The above is the end of one cycle of the method for manufacturing the preform 1. After that, the above-mentioned steps S1 to S3 are repeated by moving the transfer plate 14 by a given angle. It should be noted that when the injection molding device 10 is operated, the manufacturing of three sets of preforms 1 with a time difference of one step each is performed in parallel.

[0080] In addition, in the structure of the injection molding device 10, the injection molding process, the post-cooling process, and the removal process are of the same length. Similarly, the conveying time between each process is also of the same length.

[0081] Hereinafter, the effects of this embodiment will be described.

[0082] The rear cooling unit 12 of the injection molding device 10 of the present embodiment includes: a cooling cavity mold 21 that accommodates the preform 1 inside and contacts the outer surface of the preform; a cooling rod 22 that is inserted into the preform 1 and has a flow path for compressed air inside; and a front end member 25 that is attached to the front end side of the cooling rod 22. The front end member 25 includes: a mold surface 25a that corresponds to the shape of the bottom of the preform 1 and receives the bottom 4; and an air ejection port 25c that is formed closer to the base end side than the mold surface 25a and communicates with the flow path for compressed air. The rear cooling unit 12 cools the bottom 4 of the preform 1 while the bottom 4 is pressed against the cooling cavity mold 21 by the mold surface 25a of the front end member 25, and cools the main body 3 of the preform 1 while the main body 3 is pressed against the cooling cavity mold 21 by the compressed air passing through the air ejection port 25c.

[0083] In the present embodiment, the bottom 4 of the preform 1 is cooled by heat exchange between the front end member 25 on the inner surface side and the cooling cavity mold 21 on the outer surface side. In addition, the main body 3 of the preform 1 is pressed against the cooling cavity mold 21 by compressed air passing through the air ejection port 25c, so that the inner surface side of the main 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 demolded from the injection molding part 11 at a high temperature can be efficiently cooled in a short time, and the reduction in dimensional accuracy of the preform 1 caused by thermal shrinkage can be suppressed.

[0084] In the present embodiment, the bottom 4 of the preform 1 is pressed by the front end member 25, thereby suppressing the irregular shrinkage deformation of the preform 1 demolded at high temperature. In addition, by pressing the mold surface 25a of the front end member 25 and the cooling cavity mold 21 during cooling, the shape of the bottom 4 of the preform 1 can be maintained. In addition, the main body 3 of the preform 1 is cooled while being pressed against the cooling cavity mold 21 by compressed air passing through the air ejection port 25c, so that the main body 3 can be maintained in a shape that imitates the cooling cavity mold 21. Therefore, the preform 1 that is easily deformed when demolded from the injection molding part 11 at high temperature can be maintained in a desired shape during cooling, so that the dimensional accuracy of the shape of the preform 1 can be improved.

[0085] Furthermore, in the present embodiment, by performing auxiliary cooling of the preform 1 in the take-out section 13 , it is possible to more reliably suppress deformation of the taken-out preform 1 and reduction in dimensional accuracy due to thermal shrinkage.

[0086] In addition, by cooling the preform 1 in the post-cooling section 12, the preform 1 can be demolded even at a high temperature in the injection molding section 11, and the cooling time of the preform 1 in the injection molding section 11 can be greatly shortened. Therefore, according to the present embodiment, the molding of the next preform 1 can be started quickly, so the molding cycle time of the preform 1 can be shortened.

[0087] In addition, the injection molding device 10 supports the neck 2 of the preform 1 by the neck mold 16 from molding to removal, and maintains the neck 2 always facing upward and the body 3 always in the vertical direction. That is, the preform 1 is not molded in the horizontal direction in the injection molding part 11, and the preform 1 is not demolded from the neck mold 16 when the preform 1 is conveyed and transported.

[0088] Here, the preform molded under the condition of short cooling time and demolded from the injection mold is soft except for the neck 2, and the main body 3 and the bottom 4 are easily deformed. For example, when the preform is injection molded in the horizontal direction, when demolded from the injection mold, the main body 3 and the bottom 4 sag and bend due to their own weight, and the preform 1 that meets the standards or requirements cannot be molded. In addition, when the preform 1 is separated from the neck mold 16 and transported and transferred between the injection molding part 11 and the post-cooling part 12, since the main body 3 and the bottom 4 are deformed due to vibration, etc., the preform 1 cannot be accommodated in the cooling cavity mold 21 of the post-cooling part 12 with good position accuracy, and cannot be properly cooled. In addition, the preform 1 after cooling will remain with bending defects and deformation defects.

[0089] According to the injection molding apparatus 10 of the present embodiment, deformation of the preform 1 during release from the injection mold or during transfer can be suppressed, so even if the molding cycle time is shortened, the above-mentioned problem does not occur.

[0090] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the gist of the present invention.

[0091] In the aftercooling section 12 of the above-described embodiment, an example is described in which compressed air is introduced into the preform 1 from the air outlet 25c of the front end member 25 and the compressed air is discharged 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 discharge the compressed air from the front end member 25 side.

[0092] In the above embodiment, an example is described in which auxiliary cooling of the preform 1 is performed by spraying compressed air in the take-out section 13. However, the structure for spraying compressed air in the take-out section 13 may not be provided, and auxiliary cooling of the preform 1 may not be performed in the take-out section 13.

[0093] In the above embodiment, an example is described in which the neck mold 16 is opened to remove the preform after the ejection section 13 performs auxiliary cooling of the preform 1 by ejecting compressed air. However, the ejection section 13 may eject compressed air after the neck mold 16 is opened to perform auxiliary cooling of the preform 1 and eject the preform at the same time.

[0094] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0095] Description of Reference Numerals

[0096] 1…preform, 2…neck, 3…main body, 4…bottom, 10…injection molding device, 11…injection molding section, 12…rear cooling section, 13…removal section, 14…transfer plate, 16…neck mold, 21…cooling cavity mold, 22…cooling rod, 23…fitting core, 25…front end member, 25a…mold surface, 25b…air flow path, 25c…air outlet, 31…removal core, 32…air inlet pipe.

Claims

1. A preform manufacturing device, comprising: An injection molding section that injection molds a bottomed cylindrical preform made of resin using an injection mold; a post-cooling section that cools the preform produced by the injection molding section; as well as a take-out section for taking out the preform cooled by the post-cooling section to the outside of the device, The post-cooling unit has: A first mold, which receives the preform inside and contacts the outer surface of the preform; as well as a second mold inserted into the preform, the second mold comprising at least a cooling rod and a front end member mounted on the front end side of the cooling rod, the cooling rod having a flow path for compressed air inside, The front end member includes: a mold surface corresponding to the shape of the bottom of the preform and receiving the bottom; and an opening portion formed on the base end side of the mold surface and communicating with the flow path of the compressed air, The rear cooling section cools the bottom of the preform while pressing the bottom of the preform against the first mold using the mold surface of the front end member, and cools the main body of the preform while pressing the main body of the preform against the first mold using the compressed air passing through the opening.

2. The preform manufacturing device according to claim 1, wherein: The second mold further includes a cylindrical core mold that abuts against a neck portion of the preform.

3. The preform manufacturing device according to claim 1, wherein: The compressed air in the post-cooling section is introduced from the opening toward the main body of the preform.

4. The preform manufacturing device according to claim 1, wherein: The take-out section includes an auxiliary cooling section for introducing compressed air into the preform.

5. The preform manufacturing device according to claim 4, wherein: The auxiliary cooling unit introduces compressed air into the preform before the preform is released from the neck mold holding the preform.

6. The preform manufacturing device according to any one of claims 1 to 5, wherein: In the injection molding section, after the filling and pressure holding of the resin material are completed, the injection mold is opened, and the preform after the filling and pressure holding is carried out from the injection mold without being cooled.

7. The preform manufacturing device according to any one of claims 1 to 5, wherein: 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.

8. A method for manufacturing a preform, comprising: An injection molding step of injection molding a bottomed cylindrical preform made of resin using an injection mold; a post-cooling step of cooling the preform produced by the injection molding part; as well as a taking-out step of taking out the preform cooled by the post-cooling section to the outside, Application in the post-cooling process: A first mold, which receives the preform inside and contacts the outer surface of the preform; as well as a second mold inserted into the preform, the second mold comprising at least a cooling rod and a front end member mounted on the front end side of the cooling rod, the cooling rod having a flow path for compressed air inside, The front end member includes: a mold surface corresponding to the shape of the bottom of the preform and receiving the bottom; and an opening portion formed on the base end side of the mold surface and communicating with the flow path of the compressed air, In the post-cooling process, the bottom of the preform is cooled while being pressed against the first mold by the mold surface of the front end part, and the main body of the preform is cooled while being pressed against the first mold by the compressed air passing through the opening.

9. A cooling mold, which is used for a post-cooling section of a preform manufacturing device, the preform manufacturing device comprising: an injection molding section, which injection molds a bottomed cylindrical resin preform using an injection mold; the post-cooling section, which cools the preform manufactured by the injection molding section; and a removal section, which removes the preform cooled by the post-cooling section to the outside of the device, The cooling mold has: A first mold, which receives the preform inside and contacts the outer surface of the preform; as well as a second mold inserted into the preform, the second mold comprising at least a cooling rod and a front end member mounted on the front end side of the cooling rod, the cooling rod having a flow path for compressed air inside, The front end member comprises: A mold surface corresponding to the shape of the bottom of the preform and receiving the bottom; and an opening portion which is formed on the base end side of the mold surface and communicates with the flow path of the compressed air.

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