Temperature adjustment mold, and apparatus and method for producing resin container

Abstract

This temperature adjustment mold for adjusting the temperature of a bottomed cylindrical resin preform includes: a heat absorption rod which is inserted into the preform in such a manner that there is a gap between the heat absorption rod and the inner circumference of the preform, and which cools the preform from the inside in a non-contact manner; and one or more heat absorption pieces which are attached to the heat absorption rod in a detachable manner so as to partially cover the heat absorption rod, and which adjust the gap in the radial direction between the heat absorption rod and the preform. The heat absorption pieces are thermally connected to the heat absorption rod when the heat absorption rod is attached, and partially cool the preform in a non-contact manner.

Description

Temperature-regulating mold, resin container manufacturing device and manufacturing method

[0001] The present invention relates to a temperature-regulating mold, a manufacturing apparatus for a resin container, and a manufacturing method thereof.

[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] Generally, a preform immediately after injection molding does not have a temperature distribution suitable for forming a container. Therefore, in a hot parison container manufacturing cycle, a temperature adjustment process for the preform is carried out between the injection molding process and the blow molding process to prevent temperature deviation in the preform or to provide the preform with a desired temperature distribution suitable for forming a container.

[0004] For example, from the viewpoint of shortening the manufacturing cycle of resin containers and promoting high-speed molding of containers, it is required to shorten the cooling time of the preform in the injection mold as much as possible in the injection molding process. In order to ensure the quality of containers during such high-speed molding, it is all the more important to appropriately adjust the temperature distribution of the preform in the temperature adjustment process.

[0005] In this type of temperature adjustment process, a temperature adjustment rod mold is sometimes inserted inside the preform to adjust the temperature of the inner periphery of the preform. For example, as in Patent Document 1, it has been proposed to insert a temperature adjustment rod mold with an uneven circumferential shape inside the preform in the temperature adjustment process to partially cool the preform that is in contact with the mold.

[0006] Special Publication No. 7-61675

[0007] When the preform is cooled by contact with the temperature control mold during the temperature control process, the temperature of the preform may drop too much due to heat conduction to the low-temperature mold, resulting in poor thickness distribution in the container. Also, depending on the preform material, problems such as the resin sticking to the temperature control mold and resulting deformation of the preform may occur when demolding.

[0008] Furthermore, when cooling the preform by introducing compressed air into the inside of the preform in the temperature adjustment step, it is difficult to create local temperature differences in the circumferential or axial direction, and it is relatively difficult to eliminate temperature deviations or intentionally create biases in the temperature distribution. Furthermore, when cooling with compressed air, the preform is pressed from the inside by the compressed air and comes into contact with the cavity mold on the outer periphery, so cooling using compressed air itself may be difficult depending on the material of the preform.

[0009] The present invention has been made in view of these problems, and aims to provide a temperature-regulating mold that can cool a preform without contacting the mold and appropriately regulate the temperature distribution on the inner circumferential side of the preform.

[0010] One aspect of the present invention is a temperature control mold for controlling the temperature of a bottomed, cylindrical resin preform. The temperature control mold includes a heat absorption rod that is inserted into the preform with a gap between it and the inner periphery of the preform and that cools the preform from the inside without contact, and one or more heat absorption pieces that are detachably attached to the heat absorption rod so as to partially cover the heat absorption rod and adjust the radial gap between the heat absorption rod and the preform. The heat absorption pieces are thermally connected to the heat absorption rod when the heat absorption rod is attached, and partially cool the preform without contact.

[0011] According to one aspect of the present invention, it is possible to provide a temperature adjusting mold that can cool a preform without contacting the mold and appropriately adjust the temperature distribution on the inner circumferential side of the preform.

[0012] Fig. 1 is a diagram schematically showing the configuration of a blow molding device of this embodiment; Fig. 2 is a vertical cross-sectional view showing an example of the configuration of a temperature adjustment unit of this embodiment; Fig. 3 is a perspective view showing an example of the configuration of a heat absorption rod of this embodiment; Fig. 4 is a diagram showing a state in which heat absorption pieces are partially attached in the circumferential direction of the rod body; Fig. 5 is a flowchart showing steps in a method for manufacturing a container; Fig. 6 is a vertical cross-sectional view showing a modified example of the temperature adjustment unit of this embodiment;

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, the same elements will be given the same reference numerals in the drawings. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown schematically and do not represent the actual shapes, dimensions, etc.

[0014] 1 is a diagram schematically illustrating the configuration of a blow molding apparatus 10 according to this embodiment, which is applied to the production of resin containers (hereinafter also referred to simply as containers). The blow molding apparatus 10 is an example of a container production apparatus, and employs a hot parison method (also referred to as a one-stage method) in which a container is blow-molded by utilizing the heat retained (internal heat) during injection molding without cooling a preform 1 (not shown in FIG. 1) to room temperature.

[0015] The blow molding device 10 includes an injection molding unit 11, a temperature adjustment unit 12, a blow molding unit 13, a take-out unit 14, and a conveying mechanism 16. The injection molding unit 11, the temperature adjustment unit 12, the blow molding unit 13, and the take-out unit 14 are arranged at positions rotated by a predetermined angle (e.g., 90 degrees) around the conveying mechanism 16.

[0016] (Transport mechanism 16) The transport mechanism 16 includes a transport plate (not shown) that moves in a rotational direction around an axis perpendicular to the plane of the paper in Fig. 1. The transport plate is composed of a single disk-shaped flat plate member or a plurality of roughly fan-shaped flat plate members divided into individual molding stations. One or more neck dies 17 (not shown in Fig. 1) that hold the neck portion 2 of the preform 1 (or the neck portion of the container) are arranged on the transport plate at predetermined angular intervals.

[0017] The transport mechanism 16 is equipped with a rotation mechanism (not shown) and moves a transfer plate to transport the preform 1 (or container) having the neck portion 2 held by the neck mold 17, in the order of injection molding section 11, temperature adjustment section 12, blow molding section 13, and removal section 14. The transport mechanism 16 further includes a lifting mechanism (vertical mold opening / closing mechanism) and a neck mold opening mechanism, and performs operations to lift the transfer plate and operations related to mold closing and mold opening (mold release) in the injection molding section 11, etc.

[0018] (Injection molding section 11) The injection molding section 11 is equipped with an injection cavity mold and an injection core mold (not shown), and manufactures the preform 1 shown in Fig. 2. The injection molding section 11 is connected to an injection device 15 that supplies a resin material, which is the raw material of the preform 1.

[0019] In the injection molding section 11, the injection cavity mold, the injection core mold, and the neck mold 17 of the transport mechanism 16 are closed to form a mold space in the shape of a preform. Then, a molten resin material is injected from an injection device 15 into this mold space in the shape of a preform, thereby producing a preform 1 in the injection molding section 11.

[0020] Here, the overall shape of the preform 1 is a cylindrical shape with one end open and the other end closed at a bottom. As shown in Fig. 2 described later, the preform 1 has a neck portion 2 formed at one end with an opening, a body portion 3 connected to the neck portion 2 and formed into a cylindrical shape, and a bottom portion 4 connected to the body portion 3 and closing the other end.

[0021] The material of the container and the preform 1 is a thermoplastic synthetic resin, and can be appropriately selected depending on the application of the container. Specific types of material include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (polycyclohexanedimethylene terephthalate), Tritan (Tritan (registered trademark): a copolyester manufactured by Eastman Chemical Company, a polyester copolymer using cyclobutanediol as a monomer), 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).

[0022] Although not particularly limited, the preform 1 in this embodiment corresponds to, for example, a large container used in a water server or the like. The material of the preform 1 in this embodiment may be polyethylene terephthalate (PET), polycarbonate (PC), Tritan, or the like. The capacity of the large container is, for example, 2 liters to 20 liters, and preferably 12 liters to 20 liters.

[0023] It should be noted that even when the injection molding section 11 is opened, the neck mold 17 of the transport mechanism 16 does not open, but continues to hold and transport the preforms 1. The number of preforms 1 that are simultaneously molded in the injection molding section 11 (i.e., the number of containers that can be simultaneously molded by the blow molding apparatus 10) can be set as appropriate.

[0024] (Temperature Adjustment Unit 12) The temperature adjustment unit 12 adjusts the temperature of the preform 1 transported from the injection molding unit 11 to a temperature suitable for the final blow (for example, about 170°C to 180°C when the material is PC), by uniformly adjusting the temperature of the preform 1, and by eliminating temperature deviations and adjusting the temperature distribution. The temperature adjustment unit 12 also has the function of cooling the preform 1 in a high-temperature state after injection molding.

[0025] 2 is a vertical cross-sectional view showing an example of the configuration of the temperature adjustment unit 12 of this embodiment. The temperature adjustment unit 12 includes a temperature adjustment cavity mold (heating pot type or temperature adjustment pot type) 21 capable of accommodating the preform 1, and a heat absorption rod (temperature adjustment rod in a broad sense) 22 inserted inside the preform 1.

[0026] The temperature control cavity mold 21 is an example of a temperature control mold, and is a mold having a temperature control space capable of accommodating the preform 1 held in the neck mold 17. The temperature control space is open at the top and formed in a cylindrical shape with a bottom corresponding to the shape of the preform 1. The inner diameter of the space in the temperature control cavity mold 21 is larger than the outer shape (or maximum outer diameter) of the preform, and the axial length of the space in the temperature control cavity mold 21 is set to be longer than the length of the preform 1. This makes it possible to insert the preform 1 into the space in the temperature control cavity mold 21 from above and accommodate the preform 1 without it coming into contact with the inner surface of the temperature control cavity mold 21.

[0027] The temperature-controlled cavity mold 21 is, for example, a heating pot type provided with one or more stages in the axial direction of the preform 1 and heats the preform 1 without contact. The temperature-controlled cavity mold 21 is preferably composed of block members stacked in multiple stages (e.g., eight stages) in the axial direction of the preform 1. A heating element (not shown), such as a band heater, is attached to each block member. The temperature of each block member is maintained at a predetermined temperature by the heating element, and the body portion 3 and bottom portion 4 of the housed preform 1 can be heated without contact by radiant heat. The temperature of the heating element is appropriately set in the range of 150 to 275°C; for example, it is appropriately set between 150 and 200°C when the material of the preform 1 is PC, and between 200 and 275°C when the material is PET or Tritan.

[0028] In addition, if there is no sticking between the outer surface of the preform 1 and the cavity surface, the temperature-controlled cavity mold 21 may be a temperature-controlled pot mold equipped with a flow path for flowing a temperature-controlled medium (cooling medium) inside. The temperature of the temperature-controlled cavity mold 21 is maintained at a predetermined temperature by the temperature-controlled medium flowing inside the mold. As a result, the temperature-controlled cavity mold 21 can adjust the temperature of the contained preform 1 by contacting its outer surface. The temperature of the temperature-controlled medium is not particularly limited, but is appropriately set within a range of 100°C to 200°C, preferably 140°C to 180°C, for example, when the material of the preform 1 is PC. In addition, the temperature-controlled cavity mold 21 may also be divided into multiple stages in the axial direction and configured by stacking multiple block members, with each block member set to a different temperature.

[0029] The heat absorption rod 22 is an example of a temperature adjustment mold, and is arranged so as to be able to advance and retreat relative to the neck mold 17 that holds the preform 1 in the temperature adjustment unit 12. Fig. 2 shows a state in which the heat absorption rod 22 has descended to the lower side in the drawing and is inserted into the neck mold 17.

[0030] 3 is a perspective view showing an example of the configuration of the heat absorption rod 22 of this embodiment. The heat absorption rod 22 has a core portion (rod base end portion) 23, a rod body 24, and a heat absorption piece (heat absorption metal member) 25.

[0031] The core portion 23 is provided on the base end side (upper side) of the heat absorption rod 22 and has a tapered outer shape that decreases in diameter toward the tip side. The shape of the tip side of the core portion 23 corresponds to the inner peripheral shape of the neck mold 17, and a rod main body 24 is attached to the tip of the core portion 23. The core portion 23 is inserted inside the neck mold 17 when the heat absorption rod 22 descends, and serves to guide the descending heat absorption rod 22 and position the rod main body 24 with respect to the preform 1.

[0032] The rod body 24 is a hollow, rod-shaped mold member made of a mold material with high thermal conductivity, such as carbon steel or stainless steel, and extends from the tip of the core portion 23 along the axial direction of the preform 1. As shown in Fig. 2, the rod body 24 is formed to have dimensions that are thinner than the inner diameter of the preform 1 and shorter than the axial length of the preform 1. This allows the rod body 24 to be placed inside the preform 1 with a gap between it and the inner periphery of the preform 1.

[0033] The rod body 24 may not have a flow path for circulating a cooling medium inside, as long as it can be cooled by radiating cold to the outside while the heat absorption rod 22 is elevated. Note that the rod body 24 may have a flow path for circulating a cooling medium inside in order to avoid temperature increases due to heat storage in the heat absorption rod 22. This allows the temperature of the rod body 24 to be maintained at a predetermined temperature by the cooling medium flowing inside the rod body 24, and allows multiple preforms 1 to be cooled evenly even when the blow molding apparatus 10 is operated for a long period of time.

[0034] The rod main body 24 is formed as a columnar body (e.g., a rectangular column or an inverted truncated pyramid) whose cross section perpendicular to the axial direction is a regular polygon. The regular polygon may be, for example, a square, a regular hexagon, or a regular octagon. The outer surface of the rod main body 24 is provided with a plurality of elongated rectangular peripheral surface portions (flat surfaces) 24b arranged in the circumferential direction (the same number as the number of faces of the regular polygon), and a hollow cylindrical through-hole is provided on the inner surface of the rod main body 24. FIG. 3 shows, as an example, a configuration in which the rod main body 24 has a regular hexagonal cross section. As shown in FIG. 3, the rod main body 24 is configured so that a heat absorption piece 25 can be detachably attached to any region of the peripheral surface portion 24b of the rod main body 24. Note that bolt holes (piece connecting portions) 24a are provided on the surface (peripheral surface portion 24b) of the rod main body 24. The heat absorbing piece 25 is attached to the rod body 24 by a bolt (piece connecting member) 26 that is screwed into a bolt hole 24 a of the rod body 24 .

[0035] One or more heat absorption pieces 25 are detachably attached to any surface (peripheral surface portion 24b) of the outer periphery of the rod main body 24, and are mold pieces that partially cover the outer periphery of the rod main body 24. The heat absorption pieces 25 adjust the radial distance between the preform 1 and the heat absorption rod 22, and achieve a desired temperature distribution in the preform 1. More specifically, the heat absorption pieces 25 absorb heat radiated (emitted) from the inner periphery of the barrel portion 3 of the preform 1, and transfer the heat to the rod main body 24, thereby cooling the barrel portion 3.

[0036] The heat absorption top 25 is formed of, for example, a mold material with high heat conductivity, such as carbon steel or stainless steel, similar to the rod main body 24, and is thermally connected to the rod main body 24 (for example, the rod main body 24 and the heat absorption top 25 are in contact) when attached to the rod main body 24. The heat absorption top 25 may be formed of the same material as the rod main body 24, or may be formed of a different material.

[0037] The outer peripheral surface of each heat absorption top 25 facing the preform 1 is curved to match the inner peripheral surface of the preform 1, and the inner peripheral surface facing the rod main body 24 is flat. The heat absorption tops 25 are configured as strips whose outer peripheral sides are arc-shaped in plan view, corresponding to the cross-sectional shape of the rod main body 24. This allows each heat absorption top 25 to cover a range on the inner circumference of the preform 1 that is 1 / the number of circumferential surfaces 24b (i.e., 1 / the number of faces or corners of the regular polygon of the rod main body 24). For example, if the cross section of the rod main body 24 is a regular hexagon, the heat absorption tops 25 will be strips that form a sextant arc, and each heat absorption top 25 will cover 1 / 6 of the inner circumference of the preform 1.

[0038] Furthermore, the maximum radial thickness of the heat absorption top 25 is set to be smaller than the distance from the surface of the rod main body 24 to the inner periphery of the preform 1. As a result, when the heat absorption top 25 is attached, a gap is created between the heat absorption top 25 and the inner periphery of the preform 1. Therefore, when the heat absorption top 25 is attached, the heat absorption rod 22 can cool the inner periphery of the preform 1 without contacting it.

[0039] The heat absorption rod 22 of this embodiment is configured such that one or more, preferably multiple, mounting portions for the heat absorption pieces 25 are provided in the axial direction on each surface (each peripheral surface portion 24b) of the columnar body of the rod main body 24. For example, the heat absorption rod 22 of Fig. 3 has seven mounting portions for the heat absorption pieces 25 provided on each peripheral surface portion 24b. Therefore, the heat absorption pieces 25 can be attached to any mounting portion arranged in the circumferential and axial directions of the rod main body 24.

[0040] Note that, because the inner peripheral surface of the preform 1 is tapered (tapered), if all the heat absorption pieces 25 are made the same thickness, the gap between the inner peripheral surface of the preform 1 and the heat absorption pieces 25 will vary in the vertical direction (axial direction). To make this gap approximately the same, the thickness of the heat absorption pieces 25 connected to the rod main body 24 (or the peripheral surface portion 24b) may be varied in the vertical direction. For example, the thickness of the heat absorption pieces 25 in the vertical direction may be set such that the thickness on the neck 2 side is greater than the thickness on the trunk 3 side (or bottom 4 side). In other words, the thickness of the heat absorption pieces 25 located on the neck 4 side (the upper end side of the rod main body 24) may be greater than the thickness of the heat absorption pieces located on the trunk 3 side (or bottom 4 side, the lower end side of the rod main body 24).

[0041] Fig. 4 shows a state in which heat absorption pieces 25 are partially attached in the circumferential direction of a rod main body 24 having a regular hexagonal cross section. Fig. 4 shows an example in which two heat absorption pieces 25 are attached to the rod main body 24 side by side in the circumferential direction, and the heat absorption pieces 25 partially cover one-third of the outer periphery of the rod main body 24. For simplicity, the temperature control cavity mold 21 is not shown in Fig. 4.

[0042] As shown in Figure 4, in the preform 1 into which the heat absorption rod 22 is inserted, in a first circumferential region (region surrounded by a dashed line in Figure 4) where the heat absorption pieces 25 are attached, the radial gap S1 between the inner peripheral surface of the preform 1 and the mold is narrowed by the heat absorption pieces 25. In the first region, the radiant heat from the preform 1 is more easily absorbed by the heat absorption pieces 25 located nearby, so the temperature of the preform 1 is more likely to drop.

[0043] On the other hand, within the preform 1 into which the heat absorption rod 22 has been inserted, in a second circumferential region (region not surrounded by a dashed line in FIG. 4 ) where the heat absorption piece 25 is not attached, the inner peripheral surface of the preform 1 faces the rod main body 24, and therefore the radial gap S2 between the inner peripheral surface of the preform 1 and the mold is wider than in the first region. In the second region, the radiant heat from the preform 1 is absorbed by the rod main body 24, which is located inside the heat absorption piece 25, and therefore the temperature of the preform 1 is less likely to drop than in the first region.

[0044] As described above, in the heat absorption rod 22, the cooling strength of each portion of the preform 1 can be selectively adjusted by adjusting the attachment position of the heat absorption piece 25, making it easy to bring the temperature distribution of the preform 1 closer to a desired state. Note that, although the example of Fig. 4 has been described regarding temperature adjustment in the circumferential direction of the preform 1, the temperature in the axial direction of the preform 1 can also be adjusted in a similar manner.

[0045] (Blow molding unit 13) The blow molding unit 13 performs biaxial stretch blow molding on the preform 1 whose temperature has been adjusted in the temperature adjustment unit 12, to produce a container. The blow molding unit 13 includes a blow cavity mold, which is a pair of split molds corresponding to the shape of the container, a bottom mold, a stretch rod, and an air inlet / outlet member (none of which are shown). The blow molding unit 13 blow molds the preform 1 while stretching it. This allows the preform 1 to be shaped into the shape of the blow cavity mold, producing a container.

[0046] (Removal Section 14 ) The removal section 14 is configured to release the neck of the container manufactured in the blow molding section 13 from the neck mold 17 and remove the container to the outside of the blow molding apparatus 10 .

[0047] <Explanation of Container Manufacturing Method> Next, a container manufacturing method using the blow molding apparatus 10 of this embodiment will be described. Fig. 5 is a flowchart showing the steps of the container manufacturing method. In this embodiment, a mold adjustment step (S100) is performed before each step (S101 to S104) of the container manufacturing cycle, which will be described later, is performed.

[0048] (Step S100: Mold Adjustment Process) The mold adjustment process is a process for adjusting the attachment position of the heat absorption piece 25 on the heat absorption rod 22 in accordance with the temperature deviation of the preform 1. As an example, the following work is performed in the mold adjustment process. In the following explanation, it is assumed that adjustments are made to reduce deviations in the temperature distribution of the preform 1 and the wall thickness distribution of the container in the circumferential direction. The idea behind adjusting the attachment position of the heat absorption piece 25 in the axial direction is the same as for the circumferential direction.

[0049] First, the blow molding apparatus 10 is test-operated to obtain information on the temperature distribution of the preform 1 or the wall thickness distribution of the container before adjustment.

[0050] For example, if there is a deviation in the temperature distribution in the circumferential direction of the preform 1, the worker attaches the heat absorption piece 25 to an area of ​​the rod body 24 in the circumferential direction that faces the high-temperature part of the preform 1. As a result, in the part of the preform 1 in the circumferential direction that is hot during the test run, the radiant heat from the preform 1 is more easily absorbed by the heat absorption piece 25, and the temperature drops. Therefore, the temperature deviation in the circumferential direction of the preform 1 after adjustment is reduced.

[0051] Furthermore, when adjusting the mounting position of the heat absorbing piece 25 based on the distribution of wall thickness of the container manufactured in the test run, the following procedure may be carried out.

[0052] In one-stage blow molding, high-temperature parts of the preform 1 have a large amount of retained heat, making it easier for the preform 1 to be stretched. In other words, parts of the container with thin walls correspond to high-temperature parts of the preform 1. On the other hand, low-temperature parts of the preform 1 have less retained heat than the high-temperature parts of the preform 1, making it harder for the preform 1 to be stretched. In other words, parts of the container with thick walls correspond to low-temperature parts of the preform 1.

[0053] Therefore, when adjusting the temperature adjusting mold 30 based on the thickness distribution of the container, the thinner parts of the container are regarded as high temperature parts of the preform 1, and the thicker parts of the container are regarded as low temperature parts of the preform 1, and the attachment position of the heat absorbing piece 25 can be adjusted in the same manner as above. Once the above mold adjustment process is completed, the following steps of the container manufacturing cycle are carried out.

[0054] (Step S101: Injection Molding Process) First, in the injection molding section 11, resin is injected from the injection device 15 into a preform-shaped mold space formed by the injection cavity mold, the injection core mold, and the neck mold 17 of the transport mechanism 16 to manufacture the preform 1. Then, after the injection of the resin material (filling and pressure holding) is completed, or after a minimum or predetermined cooling time set after the completion of the injection, the injection mold of the injection molding section 11 is opened.

[0055] Although not particularly limited, from the viewpoint of manufacturing a container with a high-speed molding cycle, it is preferable to open the mold in step S101 after completing the injection of the resin material (filling and pressure holding) without providing a cooling time for the preform 1 in the injection mold. On the other hand, when performing minimal cooling of the preform 1 in the injection mold, it is preferable that the time for cooling the resin material (cooling time) after completing the injection of the resin material in the injection molding section 11 is 1 / 2 or less of the time for injecting the resin material (injection time). Furthermore, the above cooling time can be made shorter than the time for injecting the resin material depending on the weight of the resin material. For example, the cooling time is more preferably 2 / 5 or less of the injection time of the resin material, even more preferably 1 / 4 or less, and particularly preferably 1 / 5 or less.

[0056] In this embodiment, there is no cooling time for the preform 1 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 1 with high retained heat at high temperatures is molded.

[0057] When the injection molding of the preform 1 is completed, the mold in the injection molding section 11 is opened and the preform 1 is released from the injection cavity mold and the injection core mold. Next, the transfer plate of the transport mechanism 16 moves so as to rotate by a predetermined angle, and the preform 1 held in the neck mold 17 is transported to the temperature adjustment section 12 while retaining the heat retained during injection molding.

[0058] (Step S102: Temperature Adjustment Step) Subsequently, in the temperature adjustment section 12, temperature adjustment is performed to bring the temperature of the preform 1 close to a temperature suitable for the final blow.

[0059] In the temperature adjustment step, the transfer plate is lowered so that the preform 1 held in the neck mold 17 is accommodated in the temperature adjustment cavity mold 21, and the heat absorption rod 22 is inserted into the preform 1. Gaps are formed between the temperature adjustment cavity mold 21 and the preform 1, and the temperature adjustment cavity mold 21 and the heat absorption rod 22 adjust the temperature of the preform 1 to a temperature suitable for blow molding without contacting each other.

[0060] As described above, the heat absorption piece 25 is attached to the rod body 24 of the heat absorption rod 22 in accordance with the high-temperature portion of the preform 1. Therefore, the high-temperature portion of the preform 1 is cooled more strongly by the heat absorption piece 25 than other portions, and the temperature deviation of the preform 1 that occurs during injection molding is also reduced.

[0061] After the temperature adjustment step, the transfer plate of the transport mechanism 16 moves so as to rotate by a predetermined angle, and the temperature-adjusted preform 1 held in the neck mold 17 is transported to the blow molding section 13. If no cooling medium is circulating through the rod body 24 of the heat absorption rod 22, the rod body 24 of the heat absorption rod 22 and the heat absorption top 25 are left to cool outside until they are inserted into the next preform 1.

[0062] (Step S103: Blow Molding Process) Next, in the blow molding section 13, blow molding of a container is performed. First, the blow cavity mold is closed to accommodate the preform 1 in the mold space, and an air inlet / outlet member (e.g., a blow core) is lowered to contact the neck portion 2 of the preform 1. Then, a stretching rod (vertical axis stretching member) is lowered to press the bottom portion 4 of the preform 1 from the inside, and while vertical axis stretching is performed as necessary, blow air is supplied from the air inlet / outlet member to stretch the preform 1 horizontally. As a result, the preform 1 is shaped by expanding so as to fit closely into the mold space of the blow cavity mold, and is blow-molded into a container. Note that the bottom mold waits at a lower position where it does not come into contact with the bottom portion 4 of the preform 1 before the blow cavity mold is closed, and is controlled to quickly rise to the molding position before or after mold closing.

[0063] (Step S104: Container Removal Process) When blow molding is completed, the blow cavity mold is opened. This allows the container to be removed from the blow molding section 13. Next, the transfer plate of the conveying mechanism 16 moves a predetermined angle, and the container is transported to the removal section 14. In the removal section 14, the neck of the container is released from the neck mold 17, and the container is removed to the outside of the blow molding apparatus 10.

[0064] This completes one container manufacturing cycle in the container manufacturing method. Thereafter, the transfer plate of the conveying mechanism 16 is moved a predetermined angle, and the above-described steps S101 to S104 are repeated. When the blow molding apparatus 10 is in operation, the production of four sets of containers is carried out in parallel, with each set having a time difference between each step. Due to the structure of the blow molding apparatus 10, the injection molding step, temperature adjustment step, blow molding step, and container removal step all take the same amount of time. Similarly, the transport time between each step is also the same amount of time.

[0065] The effects of this embodiment will be described below. In the temperature adjustment unit 12 of this embodiment, the preform 1 can be cooled from the inside without contact by the heat absorption rod 22 inserted inside the preform 1. The temperature of the preform 1 is also adjusted from the outside without contact by the temperature control cavity mold 21. In this embodiment, the heat absorption rod 22 that performs cooling does not come into contact with the preform 1. Therefore, this embodiment can suppress problems such as poor thickness distribution of the container due to excessive cooling of the preform 1, sticking (adhering or adhering) of the resin to the mold during demolding, and deformation of the preform 1 caused by this during demolding.

[0066] For example, materials such as polycarbonate and Tritan have lower strain hardening characteristics than materials such as PET, making it difficult to adjust the wall thickness during blow molding. Strain hardening refers to the property of increasing strength through molecular orientation during the blow process, in which the weakest part of the preform (usually the hottest part) first reaches its yield point, and then the weakest part begins to stretch, until the wall thickness becomes uniform. For this reason, when blow molding a polycarbonate or Tritan preform 1, temperature adjustment before blowing is extremely important, but according to this embodiment, it is possible to easily adjust the temperature of the preform 1 to be suitable for molding a container from polycarbonate or Tritan.

[0067] Furthermore, even when the material of the preform 1 is PET, when performing high-cycle molding or when forming into a specific container shape, the PET preform 1 may be released from the injection molding section 11 (injection molding process) at a high temperature, or may be heated to a high temperature in the temperature adjustment section 12 (temperature adjustment process). In these cases, too, a heat-absorbing rod 22 may be used for the purpose of lowering the temperature of the entire preform 1 or a specific portion thereof from the inside.

[0068] Furthermore, heat absorption pieces 25 can be partially attached to the rod body 24 of the heat absorption rod 22 in correspondence with high-temperature portions of the preform 1. In the region of the preform 1 where the heat absorption pieces 25 are attached, the radial gap between the inner peripheral surface of the preform 1 and the mold is narrowed, making it easier to absorb radiant heat from the preform 1. On the other hand, in the region of the preform 1 where the heat absorption pieces 25 are not attached, the radial gap between the inner peripheral surface of the preform 1 and the mold is widened, making it harder to absorb radiant heat from the preform 1. Since the cooling strength of each portion of the preform 1 can be selectively adjusted depending on the attachment position of the heat absorption pieces 25 on the heat absorption rod 22, the temperature distribution on the inner peripheral side of the preform can be appropriately adjusted.

[0069] 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.

[0070] For example, the arrangement of the attachment portions of the heat absorption pieces 25 on the rod main body 24 is not limited to the above embodiment, and the number of attachment portions in the circumferential and axial directions can be changed as desired. For example, if the body portion 3 of the preform 1 is hot overall after injection and demolding, the heat absorption pieces 25 may be attached to all of the bolt holes (piece connecting portions) 24a of the rod main body 24.

[0071] In the above embodiment, multiple types of heat absorption tops 25 with different radial thicknesses may be prepared, and the size of the radial gap between the preform 1 and the heat absorption top 25 may be adjusted by selecting the type of heat absorption top 25 to be attached to the rod main body 24. Furthermore, the heat absorption top 25 may have a protrusion or a recess formed on its outer circumferential surface.

[0072] Furthermore, the heat absorption rod 22 of the above embodiment is not limited to adjusting the temperature deviation of the preform 1, but can also be applied to cases where a difference in the stretch ratio is provided in the circumferential direction or axial direction of the preform 1. When a difference in the stretch ratio of the preform 1 is provided, the heat absorption piece 25 may be attached to a portion of the preform 1 where the stretch ratio is to be lowered, thereby increasing the cooling strength of the heat absorption rod 22 at that portion.

[0073] Furthermore, the heat-absorbing rod 22 of the above embodiment may be applied to temperature adjustment of a preform 1 formed of a material having lower strain hardening characteristics than PET, such as polyethylene (PE) or high-density polyethylene (HDPE). Alternatively, the heat-absorbing rod 22 of the above embodiment may be applied to temperature adjustment of a preform 1 formed of PET.

[0074] In the above embodiment, a configuration example has been described in which the rod body 24 of the heat absorption rod 22 is placed inside the preform 1 with a gap between it and the inner periphery of the preform 1, and the rod body 24 is not in contact with the preform 1. However, as a modification of the above embodiment, a tip piece 27 that can come into contact with the bottom 4 of the preform 1 may be placed at the lower end of the rod body 24, as shown in Fig. 6 .

[0075] Preforms 1 made of synthetic resins such as polycarbonate shrink as their temperature drops. In particular, preforms 1 for large containers, such as those described above, tend to shrink more in the axial direction than standard-sized preforms because of their large axial dimensions and thicker barrel walls. Therefore, in the example shown in FIG. 6 , a tip piece 27 is disposed at the lower end of the rod body 24, and the tip piece 27 abuts against the bottom 4 of the preform 1, which shrinks in the axial direction, thereby restricting the axial shrinkage of the preform 1. This reduces the likelihood of the area cooled by the heat absorption top 25 of the heat absorption rod 22 or the area heated by the heating pot being axially shifted from the target area of ​​the preform 1 where temperature adjustment is to be performed, enabling more accurate temperature adjustment of the preform 1 in the temperature adjustment unit 12.

[0076] The material of the tip piece 27 is not particularly limited, but in order to prevent excessive cooling of the bottom 4 of the preform 1, the tip piece 27 is preferably formed of a material, such as a resin material, that has lower thermal conductivity than the material of the rod body 24. Furthermore, when the heat absorption rod 22 is inserted into the preform 1, if the tip piece 27 is initially in contact with the bottom 4, the bottom 4 of the preform 1 may be excessively cooled. Therefore, it is preferable to adjust the attachment position of the tip piece 27 so that a predetermined gap is formed between the tip piece 27 and the bottom 4 of the preform 1 when the heat absorption rod 22 is inserted.

[0077] Furthermore, the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. 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.

[0078] DESCRIPTION OF SYMBOLS 1...preform, 2...neck portion, 3...body portion, 4...bottom portion, 10...blow molding device, 11...injection molding section, 12...temperature adjustment section, 13...blow molding section, 14...removal section, 15...injection device, 16...conveyor mechanism, 17...neck mold, 21...temperature control cavity mold, 22...heat absorption rod, 23...core portion, 24...rod main body, 24a...bolt hole, 25...heat absorption piece, 26...bolt, 27...tip piece

Claims

1. A temperature control mold for controlling the temperature of a bottomed cylindrical resin preform, comprising: a heat absorption rod which is inserted into the preform while leaving a gap with the inner circumference of the preform, and which cools the preform from the inside without contact; and one or more heat absorption pieces which are detachably attached to the heat absorption rod so as to partially cover the heat absorption rod, and which adjust the radial gap between the heat absorption rod and the preform, wherein the heat absorption pieces are thermally connected to the heat absorption rod when the heat absorption rod is attached, and which partially cool the preform without contact.

2. The temperature control mold according to claim 1, wherein the heat absorption rod has a plurality of mounting parts to which the heat absorption pieces can be attached, the mounting parts being arranged in the axial and circumferential directions.

3. A temperature control mold as claimed in claim 1, wherein a tip piece is attached to the axial tip of the heat absorbing rod, the tip piece contacting the bottom of the preform to restrict the axial contraction of the preform.

4. The temperature control mold according to claim 1, further comprising a cavity mold that accommodates the preform with a gap between the outer periphery of the preform and adjusts the temperature of the preform from the outside without contact.

5. A resin container manufacturing device comprising: an injection molding unit which injection molds a bottomed cylindrical resin preform; a temperature adjustment unit which adjusts the temperature of the injection molded preform; and a blow molding unit which blow molds the temperature-adjusted preform while it contains the heat retained during injection molding to manufacture a resin container, wherein the temperature adjustment unit has a temperature adjustment mold described in any one of claims 1 to 4, and the heat absorption rod to which the heat absorption piece is attached is inserted into the preform to cool the preform from the inside in a non-contact manner.

6. The resin container manufacturing device according to claim 5, wherein in the injection molding section, the time taken to cool the resin material in the injection mold after the injection of the resin material is completed is less than half the time taken to inject the resin material into the injection mold.

7. The resin container manufacturing device according to claim 5, wherein the material of the preform is any one of polycarbonate, tritan, polyethylene, high density polyethylene, and polyethylene terephthalate.

8. A method for manufacturing a resin container, comprising: an injection molding step of injection molding a bottomed cylindrical resin preform; a temperature adjustment step of adjusting the temperature of the injection molded preform; and a blow molding step of blow molding the temperature-adjusted preform while it contains the heat retained during injection molding to manufacture a resin container, wherein in the temperature adjustment step, a temperature adjustment mold described in any one of claims 1 to 4 is used, and the heat absorption rod to which the heat absorption piece is attached is inserted into the preform to cool the preform from the inside in a non-contact manner.

9. The method for manufacturing a resin container according to claim 8, further comprising a mold adjustment step of adjusting the attachment position of the heat absorption piece based on information on the temperature distribution of the preform or the thickness distribution of the container, and wherein the injection molding step, the temperature adjustment step, and the blow molding step are carried out after the mold adjustment step.

10. The method for manufacturing a resin container described in claim 8, wherein in the injection molding process, the time required to cool the resin material in the injection mold after the injection of the resin material is completed is less than half the time required to inject the resin material into the injection mold.

11. The method for manufacturing a resin container according to claim 8, wherein the material of the preform is any one of polycarbonate, tritan, polyethylene, high density polyethylene, and polyethylene terephthalate.

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