Temperature-adjusting mold and apparatus for manufacturing resin container

Abstract

To provide a temperature adjusting mold capable of suppressing the local lowering of the temperature of a preform when air cooling is performed in a temperature adjusting process to enhance the quality of a blow molded container.SOLUTION: A temperature-adjusting mold for adjusting a temperature of an injection-molded bottomed resin preform includes an air introduction member that is inserted into the preform and introduces compressed air from an air supply port into the preform to cool the preform, a cavity mold that accommodates the preform therein and comes into contact with an outer peripheral surface of the preform into which the compressed air is introduced to perform heat exchange, and a heating mechanism that heats a first region of the cavity mold facing the air supply port more than a second region of the cavity mold located on a downstream side of a flow path of the compressed air with respect to the first region.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a temperature-regulating mold and a resin container manufacturing apparatus. [Background technology]

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

[0003] In order to shorten the molding cycle of the hot parison method, it has been proposed to shorten the injection molding time of the preform, which is the rate-limiting step (for example, the cooling time of the preform in the injection mold after injection (after filling with resin)), and to perform additional cooling of the hot preform in the temperature adjustment process after injection molding. Furthermore, as a method for additionally cooling the preform, a method is known in which the outer peripheral surface of the preform is brought into contact with a cooling mold during the temperature adjustment process to perform heat exchange, and compressed air is blown into the preform to cool it (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6505344 [Patent Document 2] International Publication No. 2020 / 158918 [Patent Document 3] Patent No. 2509042 Summary of the Invention [Problem to be solved by the invention]

[0005] In this type of additional cooling of the preform, the area that is first hit by the compressed air introduced into the preform (for example, the area directly below the neck or the bottom of the preform) is cooled relatively strongly, and the heat content of that area tends to decrease during the temperature adjustment process. In other words, the area that is cooled strongly during the temperature adjustment process becomes less likely to stretch during blow molding due to the decrease in retained heat, while other areas of the preform (for example, the body of the preform) tend to stretch relatively more easily during blow molding. As a result, blow-molded containers tend to have a thick wall due to the formation of a thick wall just below the neck, while the body tends to be thin, which can lead to a large imbalance in the wall thickness distribution in the vertical direction of the container, potentially resulting in a deterioration in the quality of the container, such as its physical properties and appearance.

[0006] Therefore, the present invention has been made in consideration of such problems, and aims to provide a temperature control mold that can suppress localized temperature drops in the preform when air-cooling is performed in the temperature control process, thereby improving the quality of blow-molded containers. [Means for solving the problem]

[0007] One aspect of the present invention is a temperature control mold for controlling the temperature of an injection-molded resin preform with a bottom. The temperature control mold includes an air introduction member that is inserted into the preform and introduces compressed air from an air inlet into the interior of the preform to cool the preform, a cavity mold that houses the preform and exchanges heat by contacting the outer peripheral surface of the preform into which the compressed air has been introduced, and a heating mechanism that heats a first portion of the cavity mold facing the air inlet more than a second portion of the cavity mold that is located downstream of the first portion in a flow path of the compressed air. [Effects of the Invention]

[0008] According to one aspect of the present invention, a temperature adjustment mold can be provided that can suppress localized temperature drops in the preform when air-cooling is performed in the temperature adjustment step, thereby improving the quality of the blow-molded container. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating a configuration of a blow molding device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view showing an example of the configuration of a temperature adjustment unit. [Figure 3] 1 is a flowchart showing steps of a blow molding method. [Figure 4] FIG. 10 is a vertical cross-sectional view showing another example of the configuration of the temperature adjusting unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiments, in order to make the explanation easier to understand, the structures and elements other than the main parts of the present invention will be explained in a simplified or omitted manner. Furthermore, the same elements will be given the same reference numerals in the drawings. Note that the shapes, dimensions, etc. of the elements shown in the drawings are shown schematically and do not represent the actual shapes, dimensions, etc.

[0011] (Explanation of blow molding equipment) 1 is a diagram schematically illustrating the configuration of a blow molding apparatus 20 according to this embodiment. The blow molding apparatus 20 according to this embodiment is a hot parison type (also called a one-stage type) apparatus that blow-molds a container by utilizing the heat (internal heat, heat quantity) retained during injection molding without cooling the preform to room temperature.

[0012] The blow molding device 20 includes an injection molding section 21, a temperature adjustment section 22, a blow molding section 23, a take-out section 24, and a conveying mechanism 26. The injection molding section 21, the temperature adjustment section 22, the blow molding section 23, and the take-out section 24 are arranged at positions rotated by a predetermined angle (for example, 90 degrees) around the conveying mechanism 26.

[0013] The transport mechanism 26 includes a transfer plate 28 (not shown in FIG. 1) that moves so as to rotate around an axis perpendicular to the plane of the page in FIG. 1. On the transfer plate 28, one or more neck molds 27 (or neck mold fixing plates holding one or more neck molds, both not shown in FIG. 1) that hold the preforms 10 or the neck portions 11 of the containers are arranged at predetermined angular intervals (for example, for each molding section). The transport mechanism 26 moves the transfer plate 28 by 90 degrees at a time, thereby transporting the preforms 10 (or containers) with the neck portions 11 held by the neck molds 27, in this order: injection molding section 21, temperature adjustment section 22, blow molding section 23, and removal section 24. The transport mechanism 26 further includes a mold opening mechanism for the neck molds 27.

[0014] (Injection molding section 21) The injection molding section 21 is equipped with an injection cavity mold and an injection core mold (not shown), and manufactures the preform 10 shown in Fig. 2 described below. The injection molding section 21 is connected to an injection device 25 that supplies a resin material, which is the raw material of the preform 10.

[0015] In the injection molding section 21, the injection cavity mold, the injection core mold, and the neck mold 27 of the transport mechanism 26 are closed to form a mold space in the shape of a preform. Then, a resin material is poured from an injection device 25 into this preform-shaped mold space, whereby the preform 10 is manufactured in the injection molding section 21.

[0016] Here, the overall shape of the preform 10 is a cylindrical shape with one end open and the other end closed at its bottom. As shown in Fig. 2 described below, the preform 10 has a neck portion 11 formed at one end with an opening, a body portion 12 connected to the neck portion 11 and formed into a cylindrical shape, and a bottom portion 13 connected to the body portion 12 and closing the other end.

[0017] The material of the container and preform 10 is a thermoplastic synthetic resin and can be selected appropriately depending on the application of the container. Specific types of material include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (polycyclohexane dimethylene terephthalate), Tritan (Tritan (registered trademark): a copolyester manufactured by Eastman Chemical Co.), PP (polypropylene), PE (polyethylene), PC (polycarbonate), PES (polyethersulfone), PPSU (polyphenylsulfone), PS (polystyrene), COP / COC (cyclic olefin polymer), PMMA (polymethyl methacrylate: acrylic), and PLA (polylactic acid). PET is preferred as the material of the preform 10 and container in this application.

[0018] It should be noted that even when the injection molding section 21 is opened, the neck mold 27 of the transport mechanism 26 does not open, but continues to hold and transport the preforms 10. The number of preforms 10 that are simultaneously molded in the injection molding section 21 (i.e., the number of containers that can be simultaneously molded by the blow molding device 20) can be set as appropriate.

[0019] (Temperature adjustment section 22) The temperature adjustment unit 22 equalizes the temperature of the preform 10 manufactured in the injection molding unit 21 and eliminates temperature deviations, adjusting the temperature of the preform 10 to a temperature suitable for blow molding (e.g., approximately 90°C to 105°C) and to provide a temperature distribution suitable for the container shape to be formed. The temperature adjustment unit 22 also functions to cool the preform 10 in a high-temperature state after injection molding. If the preform 10 is made of PET, the outer surface temperature of the body portion 12 of the preform 10 will reach 120°C to 160°C during high-temperature demolding in the injection molding unit 21 or when it is carried into the temperature adjustment unit 22, and the inner portion of the body portion 12 will be even hotter than the outer surface. If PET is slowly cooled in this temperature range, crystallization (whitening) will occur, so it is necessary to rapidly cool the preform 10 in the temperature adjustment unit 22 to prevent whitening.

[0020] Fig. 2 is a vertical cross-sectional view showing an example of the configuration of the temperature adjustment unit 22. The temperature adjustment unit 22 shown in Fig. 2 has a cavity mold (temperature adjustment pot) 31 capable of accommodating the preform 10, and an air introduction member 32, as an example of a temperature adjustment mold.

[0021] The cavity mold 31 is a mold having a temperature-controlled space (cavity surface) capable of accommodating the body portion 12 of the preform 10 produced in the injection molding section 21. The cavity mold 31 shown in FIG. 2 may be divided so that the temperature of the preform 10 can be controlled / cooled at different temperatures along the axial direction (vertical direction), and may include, for example, an upper mold 31a and a lower mold 31b. The temperature-controlled space of the cavity mold 31 may have the same or different external shape as the body portion 12 of the preform 10. An example of a case in which the temperature-controlled space of the cavity mold 31 and the external shape of the body portion 12 differ is when the size (volume) of the temperature-controlled space is larger than the size of the body portion 12 of the preform 10. The cavity mold 31 may also be a single-stage structure without being divided.

[0022] The upper mold 31a is a mold that accommodates the upper side of the body portion 12 of the preform 10. The lower mold 31b is disposed below the upper mold 31a and is a mold that accommodates the lower side of the body portion 12 and the bottom portion 13 of the preform 10.

[0023] An insulating portion (air insulating layer) 31c is provided on the outer peripheral surfaces of the upper mold 31a and the lower mold 31b, dividing the outer peripheral surfaces. On the other hand, no boundary line (parting line) is formed on the inner peripheral surfaces (surfaces where the temperature-controlled space is formed) of the upper mold 31a and the lower mold 31b, and it is preferable that the upper mold 31a and the lower mold 31b are not divided. When the cavity mold 31 has a single stage, the cavity mold 31 becomes a mold in which the body portion 12 and the bottom portion 13 of the preform 10 are accommodated in a single temperature-controlled space.

[0024] The upper mold 31a and the lower mold 31b of the multi-stage cavity mold 31 (or the single-stage cavity mold 31) each have a flow path (not shown) formed therein through which a temperature control medium (refrigerant) flows. Therefore, the temperatures of the upper mold 31a and the lower mold 31b are maintained at a predetermined temperature by the temperature control medium. The temperature of the temperature control medium of the cavity mold 31 is not particularly limited, but can be appropriately selected within a range of, for example, 5°C to 90°C, preferably 30°C to 80°C. In the case of a multi-stage cavity mold 31, each stage is set to a different temperature, while in the case of a single-stage cavity mold 31, the cavity mold 31 is set to a single temperature.

[0025] The upper end of the upper mold 31a (or the upper end of the single-stage cavity mold 31) has a thin-walled, cylindrical step portion 33 that protrudes upward. An opening is formed on the inner periphery of the step portion 33, penetrating the upper mold 31a in the vertical direction to accommodate the body portion of the preform 10. The upper end of the step portion 33 faces the bottom surface of the neck mold, and the inner periphery of the step portion 33 faces the upper end of the body portion of the preform 10 (directly below the neck portion). 2, the step portion 33 facing the upper end of the body portion of the preform 10 is an example of the first portion of the cavity mold 31. In addition, in FIG. 2, the upper mold 31a and the lower mold 31b excluding the step portion 33 (or the portion of the cavity mold 31 having a single step configuration excluding the step portion) are an example of the second portion of the cavity mold 31.

[0026] Additionally, a heating mechanism 34 is attached to the outer periphery of the stepped portion 33, surrounding the side surface of the stepped portion 33 in an annular shape. The heating mechanism 34 incorporates a heating element (a heat generating element, for example, a ring-shaped heater) 34a, and is attached in contact with the side surface of the stepped portion 33. The heating mechanism 34 is capable of adjusting the temperature independently of the temperature adjustment medium, and its temperature is set to a temperature higher than that of the temperature adjustment medium. Although not particularly limited, the temperature of the heating mechanism 34 or the temperature of the stepped portion 33 is set to, for example, about 100°C to 130°C, preferably about 100°C to 110°C, and more preferably about 100°C to 102°C.

[0027] In this way, the upper end of the body portion 12 of the preform 10 accommodated in the stepped portion 33 is heated by the heat of the heating mechanism 34 via the stepped portion 33. Because the heating mechanism 34 is configured to indirectly heat the preform 10 across the stepped portion 33 of the upper mold 31a, the heating mechanism 34 is not exposed to the inner peripheral surface of the upper mold 31a, and the inner peripheral surface of the upper mold 31a is flush.

[0028] The air introducing member 32 has a fitting core 41 and an air circulation rod 42, and is inserted inside the neck mold 27 and the preform 10. When inserted into the neck mold 27, the air introducing member 32 abuts airtightly against the neck portion 11 of the preform 10. The fitting core 41 and the air circulation rod 42 are both hollow cylindrical bodies, and the air circulation rod 42 is arranged concentrically inside the fitting core 41.

[0029] When the air introduction member 32 is inserted into the neck mold 27 , the fitting core 41 comes into close contact with the inner periphery or upper end face of the neck portion 11 , maintaining an airtight seal between the preform 10 and the air introduction member 32 . The tip of the fitting core 41 is inserted into or abuts against the neck portion 11 of the preform 10. An opening 43 is formed at the tip of the fitting core 41 for introducing compressed air (air or gaseous refrigerant) into the preform 10. The opening 43 shown in FIG. 2 is an example of an air inlet. The space formed between the fitting core 41 and the air circulation rod 42 constitutes an air supply flow path connected to an air source (not shown).

[0030] The tip of the air circulation rod 42 is inserted close to the bottom surface of the preform 10. An opening 42a is formed at the tip of the air circulation rod 42 facing the bottom 13 of the preform 10 to exhaust compressed air from inside the preform 10. Therefore, the inside of the air circulation rod 42 forms a flow path for exhaust.

[0031] (Blow molding section 23) Returning to FIG. 1, the blow molding section 23 performs stretch blow molding on the preform 10 whose temperature has been adjusted in the temperature adjustment section 22 to produce a container. The blow molding section 23 includes a blow cavity mold, which is a pair of split molds corresponding to the shape of the container, a bottom mold, a stretching rod, and an air introduction member (blow core mold, neither of which is shown) for supplying blow air. The blow molding section 23 blow-moldes the preform 10 while stretching it. This allows the preform 10 to be shaped into the shape of the blow cavity mold, thereby producing a container.

[0032] (Removal part 24) The removal section 24 is configured to release the neck of the container manufactured in the blow molding section 23 from the neck mold 27 and remove the container to the outside of the blow molding apparatus 20.

[0033] (Explanation of the blow molding method) Next, a blow molding method using the blow molding apparatus of this embodiment will be described below. Fig. 3 is a flowchart showing the steps of the blow molding method.

[0034] (Step S101: Injection molding process) First, in the injection molding section 21, resin is injected from the injection device 25 into a mold space in the shape of a preform formed by the injection cavity mold, the injection core mold, and the neck mold 27 of the transport mechanism 26, thereby producing the preform 10. Then, after the injection (filling and pressure holding) of the resin material is completed, or after a minimum cooling time has elapsed after the completion of the injection, the injection mold of the injection molding portion 21 is opened.

[0035] From the viewpoint of manufacturing a container in a high-speed molding cycle, it is preferable to open the mold in step S101 after completing the injection (filling and pressure holding) of the resin material without providing a cooling time for the preform 10 in the injection mold.

[0036] On the other hand, when minimal cooling of the preform 10 is performed within the injection mold, the time required to cool the resin material after the injection of the resin material is completed in the injection molding section 21 (cooling time) is preferably 1 / 2 or less of the time required to inject the resin material (injection time). Furthermore, the cooling time can be made shorter than the time required to inject the resin material depending on the weight of the resin material. For example, the cooling time is more preferably 2 / 5 or less of the injection time of the resin material, even more preferably 1 / 4 or less, and particularly preferably 1 / 5 or less.

[0037] In this embodiment, there is no cooling time for the preform 10 in the injection mold (or the cooling time is very short), so compared to when the preform is sufficiently cooled in the injection mold, the skin layer (surface layer in a solidified state) of the preform is formed thinner and the core layer (internal layer in a softened or molten state) is formed thicker. In other words, in this embodiment, the thermal gradient between the skin layer and the core layer is large, and a preform 10 is molded that has a high temperature and a high retained heat.

[0038] When the injection mold is opened in step S101, the preform 10 is released from the injection cavity mold and injection core mold at a high temperature that allows the outer shape to be maintained. After that, the transfer plate 28 of the transfer mechanism 26 moves so as to rotate by a predetermined angle, and the preform 10 in a high-temperature state held in the neck mold 27 is transferred to the temperature adjustment unit 22.

[0039] (Step S102: Temperature adjustment process) Next, in the temperature adjusting section 22, cooling and temperature adjustment are carried out to bring the temperature of the preform 10 close to a temperature suitable for the final blow (blow temperature). In the temperature adjustment section 22, the temperature of the preform 10 is lowered to the blow temperature, and thereafter, the temperature of the preform 10 is maintained at the blow temperature until blow molding is performed. By rapidly cooling the high-temperature preform in the temperature adjustment section 22, whitening (clouding) due to spherulite generation crystallization that can occur when the preform is slowly cooled is suppressed.

[0040] 2, in the temperature adjustment section 22, first, the preform 10 is placed in the cavity mold 31. Next, the air introduction member 32 is inserted into the neck portion 11 of the preform 10 placed in the cavity mold 31. At this time, the neck portion 11 of the preform 10 and the fitting core 41 are in close contact with each other, maintaining an airtight state between them.

[0041] Thereafter, a cooling blow is performed on the preform 10. In the cooling blow of this embodiment, compressed air is introduced into the neck portion 11 side of the preform 10 through the opening 43 of the fitting core 41, and the compressed air is exhausted from the bottom portion 13 side of the preform 10 through the opening 42a of the air circulation rod 42. Note that, prior to the cooling blow, a preliminary blow may be performed to bring the outer surface of the preform 10 into uniform contact with the temperature-controlled space of the cavity mold 31. In the preliminary blow, the compressed air is not exhausted, and the compressed air may be introduced through either the opening 43 of the fitting core 41 or the opening 42a of the air circulation rod 42.

[0042] This creates a flow of compressed air from the neck 11 side toward the bottom 13 side within the preform 10, and the compressed air cools the preform 10 from the inside. During the cooling blow, compressed air is ejected from the opening 43 of the fitting core 41, so the compressed air first comes into contact with the upper end of the body of the preform 10 (directly below the neck) facing the opening 43 of the fitting core 41. The temperature of the compressed air gradually increases as it exchanges heat with the preform 10 toward the bottom along the axial direction. Therefore, during the cooling blow, the upper end of the body of the preform 10 (directly below the neck) is cooled more strongly than the bottom or lower side of the body of the preform 10.

[0043] Furthermore, the preform 10 in the temperature adjustment section 22 remains in contact with the cavity mold 31, which is maintained at a predetermined temperature by compressed air pressure from the inside, and heat exchange (i.e., cooling and temperature adjustment of the preform 10) also occurs between the preform 10 and the cavity mold 31. This adjusts the temperature of the preform 10 from the outside so that it does not fall below a temperature suitable for blow molding, and also reduces temperature deviations that occur during injection molding. Note that the shape of the preform 10 during the temperature adjustment process is maintained in the cavity mold 31 and does not change significantly.

[0044] Here, in the upper mold 31a of the cavity mold 31, a heating mechanism 34 set to a temperature higher than the temperature of the temperature adjustment medium is attached to the outer periphery of a step portion 33 facing the upper end of the body portion of the preform 10. While the upper end of the body portion of the preform 10 is strongly cooled by the cooling blow, it is locally heated from the outside by the heat of the heating mechanism 34 via the step portion 33, so that a local temperature drop at the upper end of the body portion of the preform 10 is suppressed. As a result, the upper end of the body portion of the preform 10 can maintain the heat required for blow molding even when strongly cooled by the cooling blow.

[0045] After the temperature adjustment step, the transfer plate 28 of the transport mechanism 26 moves so as to rotate by a predetermined angle, and the temperature-adjusted preform 10 held by the neck mold 27 is transported to the blow molding section 23.

[0046] (Step S103: Blow molding process) Next, in the blow molding section 23, the container is blow molded. First, the blow cavity mold is closed to place the preform 10 in the mold space, and an air introduction member (blow core) for supplying blow air is lowered to contact the neck 11 of the preform 10. A stretching rod (vertical axis stretching member) is then lowered to press the bottom 13 of the preform 10 from the inside, and while vertical axis stretching is performed as necessary, blow air is supplied from the air introduction member to stretch the preform 10 horizontally. This causes the preform 10 to expand and shape so as to fit closely into the mold space of the blow cavity mold, and is blow-molded into a container. Before the blow cavity mold is closed, the bottom mold waits in a lower position where it does not come into contact with the bottom of the preform 10, and then quickly rises to the molding position before or after mold closing.

[0047] (Step S104: Container removal process) When the blow molding is completed, the blow cavity mold and the bottom mold are opened, thereby allowing the container to be removed from the blow molding section 23. Next, the transfer plate 28 of the conveying mechanism 26 moves so as to rotate by a predetermined angle, and the container is conveyed to the removal section 24. In the removal section 24, the neck of the container is released from the neck mold 27, and the container is removed to the outside of the blow molding apparatus 20.

[0048] This completes the series of steps in the blow molding method. Thereafter, the transfer plate 28 of the conveying mechanism 26 is rotated by a predetermined angle, and the above steps S101 to S104 are repeated. When the blow molding apparatus 20 is in operation, four sets of containers are produced in parallel, with a time lag between each step.

[0049] Due to the structure of the blow molding apparatus 20, the time that the transfer plate 28 is stopped is the same in the injection molding section 21, the temperature adjustment section 22, the blow molding section 23, and the removal section 24. Similarly, the time that the transfer plate 28 is transported between each section is also the same.

[0050] The effects of this embodiment will be described below. In the temperature adjustment section 22 of this embodiment, a high-temperature preform 10, which does not have time to cool in the injection mold (or has a very short cooling time), is placed in a cavity mold 31, and the preform 10 is cooled and its temperature adjusted by a cooling blow in which compressed air is blown into the preform 10 using an air introduction member 32. A heating mechanism 34 is provided in a first portion of the cavity mold 31 facing the compressed air inlet (a stepped portion 33 of the upper mold 31a (or the upper portion of a cavity mold 31 with a single stage)). In the temperature adjustment section 22, the portion of the preform 10 that comes into contact with the compressed air first (the upper end of the body portion) is strongly cooled during the cooling blow, but because it is locally heated from the outside by the heating mechanism 34 of the cavity mold 31, the retained heat required for blow molding can be maintained. Therefore, in this embodiment, it is possible to prevent the part of the preform 10 that first comes into contact with the compressed air from becoming difficult to stretch during blow molding, making it possible to blow mold a high-quality container with little imbalance in the thickness distribution in the vertical direction.

[0051] Furthermore, in this embodiment, the temperature drop in the portion of the preform 10 that the compressed air first comes into contact with during the cooling blow in the temperature adjustment unit 22 can be suppressed, so there is no need to use a specially shaped preform with thicker walls in that portion (e.g., directly below the neck or the upper end of the body) in order to retain sufficient heat. If a preform with this type of special shape were used, restrictions would arise, such as the appearance of the container directly below the neck becoming a stepped portion. Furthermore, even if a preform with this special shape is used, the thick portion of the preform may not fully expand during blow molding, resulting in the formation of a wall pool directly below the neck of the container, resulting in uneven wall thickness distribution in the vertical direction of the container. In contrast, this embodiment can avoid the above-mentioned problems that can occur when a preform with a special shape is used.

[0052] Furthermore, the heating mechanism 34 of this embodiment is not exposed to the inner peripheral surface of the upper mold 31a (or the cavity mold 31 having a single stage), and indirectly heats the preform 10 from the outside of the step portion 33, so there is no parting line caused by the heating mechanism 34 on the inner peripheral surface of the upper mold 31a (or the cavity mold 31 having a single stage). Therefore, even if the heating mechanism 34 is provided in the temperature adjustment unit 22, no parting line is formed in the preform 10, and traces of the cavity mold 31 are unlikely to remain on the container after blow molding, thereby further improving the quality of the container.

[0053] The heat at the upper end of the body of the preform 10 gradually transfers through the neck 11 to the neck mold 27, which has a relatively low temperature, causing the temperature to drop during molding. This phenomenon occurs regardless of the direction of the compressed air during the cooling blow. Therefore, even when compressed air is introduced through the air circulation rod 42 and exhausted from the opening 43 of the fitting core 41 (or when compressed air is introduced from the bottom 13), a configuration in which the heating mechanism 34 is provided above the cavity mold 31 is effective in suppressing or maintaining the decrease in the retained heat at the upper end of the body of the preform 10.

[0054] 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.

[0055] In the above embodiment, an example has been described in which compressed air is introduced from the neck 11 side of the preform 10 and exhausted from the bottom 13 side of the preform 10. However, the flow of compressed air in the cooling blow is not limited to the above.

[0056] Fig. 4 is a vertical cross-sectional view showing another example of the configuration of the temperature adjustment unit 22. The temperature adjustment unit 22 shown in Fig. 4 shows an example of a configuration in which compressed air is introduced from the neck 11 side and the bottom 13 side of the preform 10A. Furthermore, the preform 10A in Fig. 4 has a reduced diameter portion (an example of the upper end of the body) 12a on the upper end side of the body immediately below the neck 11, and is shaped so that the inner diameter of the body 12 is smaller than the inner diameter of the neck 11. In the explanation of Fig. 4, elements common to the configuration of Fig. 2 are assigned the same reference numerals, and duplicate explanations will be omitted.

[0057] 4 is a mold having a temperature-controlled space of approximately the same shape as the preform 10A produced in the injection molding section 21. The cavity mold 51 is divided in the axial direction of the preform 10A and includes an upper mold 51a, a middle mold 51b, and a lower mold 51c. The middle mold 51b is disposed above the lower mold 51c, and the upper mold 51a is disposed above the middle mold 51b. The bottom surface of the upper mold 51a and the top surface of the middle mold 51b are engaged with a spigot 55a, and the bottom surface of the middle mold 51b and the top surface of the lower mold 51c are engaged with a spigot 55b.

[0058] The upper mold 51a is a mold that accommodates the reduced diameter portion 12a at the upper end of the body portion of the preform 10A, and the upper surface of the upper mold 51a faces the bottom surface of the neck mold 27. The upper mold 51a has a first heating mechanism 54a, and the first heating mechanism 54a has a first heating member (heat generating element, ring-shaped heater) built in.

[0059] The middle mold 51b is a mold that accommodates the body portion 12 of the preform 10A below the reduced diameter portion 12a. A flow path (not shown) through which a temperature control medium (refrigerant) flows is formed inside the middle mold 51b. Therefore, the temperature of the middle mold 51b is maintained at a predetermined temperature (e.g., 5°C to 90°C, preferably 30°C to 80°C) by the temperature control medium, similar to the cavity mold 31 in FIG. 2. The middle mold 51b may also be provided with multiple temperature control mechanisms in the axial direction (vertical direction) so that the body portion 12 of the preform can be temperature-controlled or cooled to different temperatures in the axial direction (vertical direction). For example, in FIG. 4, a heat insulating portion (air insulating layer) 51d is provided on the outer peripheral surface of the middle mold 51b, dividing the outer peripheral surface of the middle mold 51b. Meanwhile, no boundary line (parting line) is formed on the inner peripheral surface of the middle mold 51b (the surface where the temperature-controlled space is formed).

[0060] The lower mold 51c is a mold that accommodates the bottom 13 of the preform 10A. A second heating mechanism 54b is attached to the lower mold 51c. The second heating mechanism 54b has a built-in second heating member (a heat generating element, for example, a band heater). 4, the upper mold 51a and the lower mold 51c are an example of the first portion of the cavity mold 51. Also, in FIG.

[0061] 4 are examples of heating mechanisms, and are capable of adjusting the temperature independently of the temperature adjustment medium, with the temperature being set higher than the temperature of the temperature adjustment medium. Although not particularly limited, the temperature of the first heating mechanism 54a or upper mold 51a and the temperature of the second heating mechanism 54b or lower mold 51c are set to, for example, 100°C to 130°C, preferably 100°C to 110°C, and more preferably about 100°C to 102°C.

[0062] In the temperature adjustment unit 22 of Fig. 4, an air introduction member 52 is inserted inside the neck mold 27 and the preform 10A. The air introduction member 52 differs in configuration from the air introduction member 32 of Fig. 2 in that it has an outer rod tube (second air circulation rod) 44 between the inner periphery of the fitting core 41 and the outer periphery of the air circulation rod 42. The temperature adjustment unit 22 may be configured by combining the air introduction member 32 shown in Fig. 2 with the cavity mold 51 of Fig. 4.

[0063] The air circulation rod 42 and the outer rod tube 44 are concentrically arranged on the inner periphery of the fitting core 41. As a result, a flow path for compressed air is formed between the fitting core 41 and the outer rod tube 44, between the outer rod tube 44 and the air circulation rod 42, and inside the air circulation rod 42. Furthermore, when the air introducing member 52 is inserted into the preform 10A, the tip of the outer rod tube 44 is located near the boundary between the upper mold 51a and the middle mold 51b (at the lower end of the reduced diameter portion 12 of the preform 10A).

[0064] In the air introduction member 52 of Figure 4, the space between the fitting core 41 and the rod outer tube 44 and the inside of the air circulation rod 42 each form a flow path for air supply, and the space between the rod outer tube 44 and the air circulation rod 42 forms a flow path for exhaust.

[0065] 4, during cooling blowing, compressed air is introduced into the bottom 13 side of the preform 10A through the opening 42a of the air circulation rod 42, and also into the neck 11 side of the preform 10A through the opening 43 of the fitting core 41. The compressed air introduced into the preform 10A is then exhausted from the opening 44a at the tip of the rod outer tube 44. Note that a preliminary blow may be performed before the cooling blowing to bring the outer surface of the body 12 of the preform 10 into tight contact with the preform storage space (cavity surface) of the cavity mold 51.

[0066] As a result, within the preform 10A, a flow of compressed air is generated from the neck 11 side toward the lower end of the reduced diameter portion 12, and a flow of compressed air is generated from the bottom 13 side toward the lower end of the reduced diameter portion 12, and the preform 10A is cooled from the inside by these compressed air flows.

[0067] Furthermore, the preform 10A in the temperature adjustment section 22 remains in contact with the cavity mold 51, which is maintained at a predetermined temperature by compressed air pressure from the inside, and heat exchange (i.e., cooling and temperature adjustment of the preform 10A) also occurs between the preform 10A and the cavity mold 51.

[0068] In the example of Fig. 4, compressed air is ejected from opening 42a of air circulation rod 42, so that the compressed air first comes into contact with bottom 13 of preform 10A, cooling bottom 13 of preform 10A more strongly than body 12 of preform 10A. Meanwhile, lower mold 51c of cavity mold 51 is adjusted to a temperature higher than the temperature of the temperature adjustment medium by second heating mechanism 54b, so that local temperature drops in bottom 13 of preform 10A are suppressed. This improves the shaping properties of the blow-molded container bottom and the transferability of patterns, engravings, and the like.

[0069] 4, compressed air is also ejected from the opening 43 of the fitting core 41, so that the reduced diameter portion 12a facing the neck portion 11 of the preform 10A is also strongly cooled. However, because the upper mold 51a facing the reduced diameter portion 12a is also heated by the first heating mechanism 54a, a local temperature drop in the reduced diameter portion 12a of the preform 10A is also suppressed. In this way, the reduced diameter portion 12a and bottom portion 13 of the preform 10A shown in FIG. 4 can maintain the heat required for blow molding even when they are strongly cooled by the cooling blow.

[0070] It is also possible to provide a step extending upward on the middle mold 51b, and to provide a heating mechanism at this step that corresponds to the neck portion 11 of the preform 10. Furthermore, it is also possible to provide a step extending downward on the middle mold 51b, and to provide a heating mechanism at this step that corresponds to the bottom portion 13 of the preform 10. This prevents the formation of a parting line in the preform 10, and makes it less likely that traces of the cavity mold 51 will remain on the container after blow molding.

[0071] 4 may have a single stage configuration instead of being divided into upper stage mold 51a, middle stage mold 51b, and lower stage mold 51c. A first heating mechanism 54a may be provided at the top of cavity mold 51 (at a position corresponding to the top end of body portion 12 of preform 10), and a second heating mechanism 54b may be provided at the bottom of cavity mold 51 (at a position corresponding to bottom portion 13 of preform 10). Furthermore, the first heating member built into the first heating mechanism 54a may be a band heater or an infrared heater in addition to a ring-shaped heater.

[0072] 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. [Explanation of symbols]

[0073] 10, 10A... preform, 20... blow molding device, 21... injection molding section, 22... temperature adjustment section, 23... blow molding section, 31, 51... cavity mold, 32, 52... air introduction member, 34, 54a, 54b... heating mechanism

Claims

[Claim 1] A temperature control mold for adjusting the temperature of an injection-molded resin preform having a bottom, an air introduction member that is inserted into the preform and introduces compressed air from an air inlet into the preform to cool the preform; a cavity mold that accommodates the preform inside and that performs heat exchange by contacting an outer peripheral surface of the preform into which the compressed air is introduced; a heating mechanism that heats a first portion of the cavity mold facing the air inlet more than a second portion of the cavity mold that is located downstream of the first portion in the flow path of the compressed air. Mold for temperature adjustment.

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