Molded

Abstract

To provide a molding mold equipped with a temperature control circuit that has better temperature control efficiency when molding a molded body into a cylindrical shape.SOLUTION: A molding mold includes a temperature control circuit 210 including an inflow hole 211 and an outflow hole 212 opening on a surface of a molding mold 200, and a flow path part 220 arranged so that a temperature control medium allowed to flow in through the inflow hole 211 flows out through the outflow hole. A ratio L / S of a flow path length L of the flow path part 220 from the inflow hole 211 to the outflow hole 212 to a flow path cross-sectional area S of the flow path part 220 is set to 40 or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a molding die, and more particularly to a molding die for molding a cylindrical portion of a molded article. [Background technology]

[0002] Conventionally, synthetic resin containers have been used in a wide range of fields as containers for various beverages, seasonings, etc., which are made by molding a bottomed cylindrical preform using a thermoplastic resin such as polyethylene terephthalate by injection molding, compression molding, or the like, and then molding this preform into a bottle shape by biaxial stretch blow molding.In this context, Patent Document 1 discloses a mold-divided insert used in an insert stack assembly for preform molding, which has a coolant channel formed in its main body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2008-542066 Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above background technology, the inventors have conducted extensive research to provide a molding mold that is particularly suitable for molding preforms used in the manufacture of this type of container, and that is equipped with a temperature control circuit that provides better temperature control efficiency when molding the cylindrical portion of the molded body, and as a result have completed the present invention. [Means for solving the problem]

[0005] The mold according to the present invention is a mold for molding a cylindrical portion of a molded body, The mold has a split structure including a pair of split molds that are split in the radial direction, and each of the split molds is an inlet and an outlet opening on the surface of the , without branching along the way so that the outflow from the outflow hole The split moldA temperature control circuit including a flow path portion disposed inside the Independently Preparation, The flow path section includes circumferential flow path sections arranged in a plurality of rows in the axial direction along the circumferential direction of the molding surface that molds the molded body, a connecting flow path section that connects circumferential ends of the circumferential flow path sections that are adjacent in the axial direction, an inlet flow path section connected to the inlet hole, and an outlet flow path section connected to the outlet hole, and the inlet flow path section and the outlet flow path section are each connected to a first circumferential flow path section that is arranged closest to the inlet hole and the outlet hole or a second circumferential flow path section that is arranged farthest from the inlet hole and the outlet hole at the circumferential center of the split mold, among the circumferential flow path sections arranged in a plurality of rows in the axial direction, and the opposite flow path portion or the first circumferential flow path portion is continuous without being divided along the circumferential direction of the split mold, a third circumferential flow path portion and a fourth circumferential flow path portion are arranged side by side in the axial direction between the first circumferential flow path portion and the second circumferential flow path portion, the third circumferential flow path portion and the fourth circumferential flow path portion are each divided at a circumferential center portion of the split mold and are connected to each other via the connecting flow path portion, the third circumferential flow path portion is connected to the first circumferential flow path portion via the connecting flow path portion at both circumferential end sides, and the fourth circumferential flow path portion is connected to the second circumferential flow path portion via the connecting flow path portion at both circumferential end sides, The ratio L / S of the flow path length L of the flow path portion from the inlet to the outlet to the flow path cross-sectional area S of the flow path portion is 40 or less. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a molding die equipped with a temperature control circuit that provides more efficient temperature control when molding the cylindrical portion of a molded article. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing an example of a preform to be molded in a first embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory view showing an example of a bottle-shaped container obtained by blow molding the preform shown in FIG. [Figure 3] FIG. 1 is an explanatory view showing an example of an injection molding die incorporating a molding die according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view showing a neck half as a forming mold according to the first embodiment of the present invention, with a temperature control circuit seen through. [Figure 5] FIG. 2 is a plan view showing a neck half as a forming mold according to the first embodiment of the present invention, with a temperature control circuit seen through. [Figure 6] FIG. 2 is a side view showing a neck half as a forming mold according to the first embodiment of the present invention, with a temperature control circuit seen through. [Figure 7] FIG. 4 is an explanatory diagram showing an enlarged view of a main part of a connection flow path portion. [Figure 8] 10 is a graph showing the results of a temperature analysis by simulation. [Figure 9] 10 is a graph showing the results of a temperature analysis by simulation. [Figure 10] FIG. 10 is a perspective view showing a first modified example of a neck half as a forming die according to the first embodiment of the present invention, with a temperature control circuit seen through. [Figure 11] FIG. 10 is a plan view showing a first modified example of the neck half as the forming mold according to the first embodiment of the present invention, with the temperature control circuit seen through. [Figure 12] FIG. 10 is a perspective side view of a first modified neck half serving as a forming die according to the first embodiment of the present invention, showing a temperature control circuit. [Figure 13] FIG. 10 is a perspective view showing a second modified example of the neck half as the forming mold according to the first embodiment of the present invention, with the temperature control circuit seen through. [Figure 14] FIG. 10 is a plan view showing a second modified example of the neck half as the forming mold according to the first embodiment of the present invention, with the temperature control circuit seen through. [Figure 15] FIG. 10 is a side view showing a second modified example of the neck half as the forming mold according to the first embodiment of the present invention, with the temperature control circuit seen through. [Figure 16] FIG. 10 is a perspective view showing a neck half as a forming mold according to a second embodiment of the present invention, with a temperature control circuit seen through. [Figure 17] FIG. 10 is a plan view showing a neck half as a forming mold according to a second embodiment of the present invention, with a temperature control circuit seen through. [Figure 18] FIG. 10 is a side view showing a neck half as a forming mold according to a second embodiment of the present invention, with a temperature control circuit seen through. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0009] [First embodiment] First, a first embodiment of the present invention will be described. FIG. 1 shows an example of a preform 1 to be molded in this embodiment, and FIG. 2 shows an example of a bottle-shaped container 10 obtained by blow molding the preform 1 shown in FIG.

[0010] The preform 1 shown in FIG. 1 is formed into a cylindrical shape with one open end serving as a mouth portion 2 and the other end closed by a bottom portion 3 formed in a hemispherical shape.

[0011] The mouth 2 of the preform 1 is not stretched by blow molding, but becomes the mouth 2 of the container 10 shown in Fig. 2 as is. For this reason, they are denoted by the same reference numeral. The mouth 2 of the preform 1, and by extension the mouth 2 of the container 10, is the portion that serves as the injection outlet for the contents, is molded into a cylindrical shape, and has a threaded portion 21 on the side of the open end of the mouth 2 for attaching a lid (not shown).

[0012] In addition, an annular neck ring 22 that protrudes outward in the circumferential direction is provided at the mouth 2. The preform 1 is usually formed into the shoulder 30, body 40, and bottom 50 of the container 10 by starting from the portion directly below the neck ring 22 and extending the portion below that.

[0013] A bead ring 23 is provided in an annular shape along the circumferential direction between the threaded portion 21 and the neck ring 22. A flap or a hook formed on a tamper-evident band of the lid (not shown) is engaged with the bead ring 23.

[0014] Next, the molding die according to this embodiment will be described. Fig. 3 shows an example of an injection molding die 100 for injection molding the preform 1 shown in Fig. 1. In this example, the molding die according to this embodiment is incorporated into the injection molding die 100 as neck halves 200, which are a pair of split dies that mold the outer peripheral surface of the mouth portion 2 side of the preform 1, and has a split structure in which the die is split radially in consideration of the mold opening when molding the outer peripheral surface of the mouth portion 2 side, including the thread portion 21, bead ring 23, and neck ring 22 in that order along the axial direction from the open end side.

[0015] Here, an example of an injection molding die 100 shown in Figure 3 includes a pair of neck halves 200 that are incorporated as a molding die according to this embodiment, as well as a cavity die 300 that molds the outer peripheral surface side of the preform 1 and a core die 400 that molds the inner peripheral surface side of the preform 1, but the cavity die 300 and core die 400 can be any conventional die as appropriate. In addition, the cavity mold 300 is usually provided with a gate that serves as the resin injection port at a position corresponding to the bottom 3 side of the preform 1, but in the example shown in Figure 3, the internal structure of the mold including the gate is not shown.

[0016] In this embodiment, each of the neck halves 200 is independently provided with a temperature control circuit 210 for circulating a temperature control medium, such as cooling water, therein. In each of the neck halves 200, the molding surface that molds the outer peripheral surface of the mouth portion 2 side of the preform 1 is provided with protrusions 21f, 22f, and 23f that mold the thread portion 21, neck ring 22, and bead ring 23, respectively. The neck halves 200 can be configured to be mirror-symmetric with respect to the parting line PL, except for the protrusion 21f that molds the thread portion 21. For this reason, the following will focus on one of the neck halves 200 and describe the temperature control circuit 210 provided in the neck half 200.

[0017] FIG. 4 is an oblique view of the neck half 200 showing the temperature control circuit 210 through it, FIG. 5 is a plan view of the same, and FIG. 6 is a side view of the same. In all figures, the temperature control circuit 210 is shown in solid lines, and the outline of the neck half 200 is shown in dashed double-dashed lines.

[0018] As shown in these figures, the neck half 200 has an inlet 211 and an outlet 212 that open on its surface. The temperature control circuit 210 is configured such that a temperature control device (not shown) is connected to the inlet 211 and the outlet 212, and the temperature control medium that flows in through the inlet 211 flows through a flow path 220 disposed inside the neck half 200 and flows out from the outlet 212.

[0019] In configuring the temperature control circuit 210 in this manner, the inlet holes 211 and outlet holes 212 can be arranged according to the flow path of the temperature control medium from the temperature control device side to the neck half 200. In the example shown, they are arranged at predetermined intervals along the circumferential direction on the top surface of the neck half 200. The flow path section 220 is preferably formed in the shape of a pipe with a circular cross section as shown in the figure, but can also be formed in any cross section shape, such as an elliptical cross section, as necessary.

[0020] In addition, one neck half 200 and the other neck half 200 may share a temperature control device connected to their respective temperature control circuits 210, or a temperature control device may be connected individually to each temperature control circuit 210.

[0021] In this embodiment, in order to circulate the temperature control medium at a sufficient flow rate and improve the temperature control efficiency, the flow path section 220 is designed so that the ratio L / S of the flow path length L of the flow path section 220 from the inlet hole 211 to the outlet hole 212 to the flow path cross-sectional area S of the flow path section 220 is 40 or less. When designing the flow path section 220 in this manner, in order to suppress an increase in the flow resistance of the temperature control medium, it is preferable that the flow path cross-sectional area S of the flow path section 220 does not increase or decrease significantly between any adjacent regions along the flow path, and it is particularly preferable that it be constant within the tolerance range of the allowable dimensional accuracy. When the flow path cross-sectional area S of the flow path section 220 is not constant, the flow path cross-sectional area S can be calculated as the average value of the flow path cross-sectional area over the entire length of the flow path section 220.

[0022] Furthermore, the flow path section 220 is preferably configured to include circumferential flow path sections 230 arranged in multiple rows in the axial direction along the circumferential direction of the molding surface that molds the outer peripheral surface of the mouth section 2 side of the preform 1, and a connection flow path section 240 that connects the circumferential ends of axially adjacent circumferential flow path sections 230. In order to ensure a sufficient flow rate of the temperature control medium circulating through the temperature control circuit 210 while suppressing an increase in flow resistance of the temperature control medium, the connection flow path section 240 is preferably configured to be connected to each of the circumferential ends of axially adjacent circumferential flow path sections 230 via arc-shaped curved sections, thereby connecting the circumferential ends of the circumferential flow path sections 230. In the connecting flow path section 240 that connects the circumferential ends of the circumferential flow path sections 230 to each other, a linear section may be interposed between the arc-shaped curved sections that connect the respective ends of one circumferential flow path section 230 and the other circumferential flow path section 230, depending on the interval between adjacent circumferential flow path sections 230 in the axial direction, i.e., the distance between the connected objects.

[0023] By configuring the flow path 220 in this way, it becomes possible to control the temperature of the neck halves 200 so that the mouth 2 side of the preform 1 can be efficiently cooled while suppressing uneven cooling in the circumferential direction when molding the mouth 2 side of the preform 1 with the pair of neck halves 200. This makes it difficult for deformation to occur on the mouth 2 side even if the molding cycle is shortened, and as a result, the manufacturing efficiency of the preform 1 can be improved.

[0024] Furthermore, in order to more effectively suppress an increase in the flow resistance of the temperature control medium in the connection flow path section 240, it is preferable to design the connection flow path section 240 so that the radius of curvature R of the flow path center (center line CL of the portion) at the arc-shaped curved portion of the connection flow path section 240 is larger than the flow path radius r of the portion (see FIG. 7). When the arc-shaped curved portion of the connection flow path section 240 is formed to have an elliptical cross section, it is preferable to form it so that its major axis extends along the contact plane of the center line CL of the portion and its minor axis extends along the normal plane of the center line CL of the portion, or vice versa. In either case, the radius of the flow path along the contact plane of the center line CL of the portion (the major radius in the former case, the minor radius in the latter case) is taken as the flow path radius r, and is compared with the radius of curvature R on the contact plane.

[0025] Furthermore, from the viewpoint of improving temperature control efficiency, it is preferable to design the flow path length L of the flow path section 220 based on the maximum length Lc along the circumferential direction of the molding surface. More specifically, when molding the outer peripheral surface of the mouth section 2 side of the preform 1 shown in Fig. 1, the ratio L / Lc of the flow path length L of the flow path section 220 to the maximum length Lc along the circumferential direction of the molding surface excluding the ridge molding sections 21f, 22f, and 23f engraved on the molding surface is preferably 1.9 or more, and more preferably 2.3 or more.

[0026] When molding the outer peripheral surface of the mouth portion 2 of the preform 1 shown in Figure 1, the length measured along the circumferential direction of the portion on the molding surface that is molded between the bead ring 23 and the neck ring 22 is the maximum length Lc.

[0027] 4 to 6 , the flow path length L of the flow path section 220 can be adjusted appropriately by providing the inlet hole 211 and the outlet hole 212 at positions away from the molding surface and providing the inlet flow path section 221 and the outlet flow path section 222 between the inlet hole 211 and the outlet hole 212 and the circumferential flow path section 230. In such an embodiment, the inlet flow path section 221 connected to the inlet hole 211 can be connected to the circumferential flow path section 230 via the inlet-side connecting flow path section 241 at the circumferential center of the neck half 200, and the outlet flow path section 222 connected to the outlet hole 212 can be connected to the circumferential flow path section 230 via the outlet-side connecting flow path section 242 at the circumferential center of the neck half 200. As with the connection flow path section 240, the inlet side connection flow path section 241 and the outlet side connection flow path section 242 are preferably connected to their respective connection targets via arc-shaped curved sections in order to suppress an increase in the flow resistance of the temperature control medium, and are preferably designed so that the radius of curvature of the center of the flow path at the arc-shaped curved section (the radius of curvature on the contact plane of the center line CL of that section) is larger than the flow path radius of that section (the radius of the flow path along the contact plane of the center line CL of that section).

[0028] When providing such inlet flow passages 221 and outlet flow passages 222, it is possible to appropriately select which of the circumferential flow passages 230 arranged in a plurality of rows in the axial direction the inlet flow passages 221 and outlet flow passages 222 are connected to. In the embodiment shown in FIGS. 4 to 6, the inlet flow passages 221 and outlet flow passages 222 are connected to the first circumferential flow passages 231 arranged closest to the inlet holes 211 and outlet holes 212. The flow passages 220 are configured so that the second circumferential flow passages 232 arranged farthest from the inlet holes 211 and outlet holes 212 are continuous without being interrupted along the circumferential direction of the neck half 200, so that the temperature control medium introduced through the inlet holes 211 passes through the flow passages 220 and flows out of the outlet holes 212.

[0029] In such an embodiment, although not shown, the first circumferential flow path portion 231 and the second circumferential flow path portion 232 may be connected at both circumferential ends thereof via connecting flow path portions 240. Furthermore, in order to suppress an increase in the flow resistance of the temperature control medium, it is preferable that the inlet flow path portion 221 and the outlet flow path portion 222 extend in a curved manner from the inlet hole 211 and the outlet hole 212, respectively, toward the first circumferential flow path portion 231, as shown in the drawing.

[0030] Furthermore, the second circumferential flow path portion 232 is preferably disposed corresponding to the portion of the molding surface with the longest circumferential length, excluding the ridge molding portions 21f, 22f, and 23f engraved on the molding surface. More specifically, when molding the mouth portion 2 side of the preform 1 shown in FIG. 1 , excluding the thread portion 21, neck ring 22, and bead ring 23, the mouth portion 2 side is designed so that the outer diameter is largest between the bead ring 23 and the neck ring 22. For this reason, as described above, the length measured circumferentially of the portion on the molding surface that molds between the bead ring 23 and the neck ring 22 is the maximum length Lc, and therefore the second circumferential flow path portion 232 is preferably disposed corresponding to this portion.

[0031] The reason for this is as follows: The area between the bead ring 23 and the neck ring 22 on the mouth portion 2 side of the preform 1 is designed to be relatively thick, and since this area has a large amount of resin, it is more difficult to cool than other areas and tends to be prone to uneven cooling in the circumferential direction. From this perspective, it is preferable to arrange a second circumferential flow path portion 232 that is continuous without being interrupted along the circumferential direction of the neck half 200 in correspondence with the area where the area between the bead ring 23 and the neck ring 22 is to be molded, so that the area between the bead ring 23 and the neck ring 22 can be efficiently cooled while suppressing uneven cooling in the circumferential direction.

[0032] Furthermore, when arranging the circumferential flow passage sections 230 side by side in a plurality of rows in the axial direction, the number of rows can be appropriately designed depending on the size (particularly the axial length) of the neck half 200, etc., so as to ensure a sufficient flow passage length L of the flow passage section 220. In the embodiment shown in Figures 4 to 6, a third circumferential flow passage section 233 and a fourth circumferential flow passage section 234 are arranged side by side in the axial direction between a first circumferential flow passage section 231 and a second circumferential flow passage section 232, so that the circumferential flow passage sections 230 are arranged side by side in four rows.

[0033] In such an embodiment, it is preferable that the third circumferential flow passage portion 233 and the fourth circumferential flow passage portion 234 are separated from each other at the circumferential center of the neck half 200 and are connected to each other via the connecting flow passage portion 240. It is also preferable that the third circumferential flow passage portion 233 is connected to the first circumferential flow passage portion 231 via the connecting flow passage portion 240 at both circumferential end sides, and the fourth circumferential flow passage portion 234 is connected to the second circumferential flow passage portion 232 via the connecting flow passage portion 240 at both circumferential end sides.

[0034] Furthermore, when the third circumferential flow path section 233 and the fourth circumferential flow path section 234 are arranged side by side, in order to suppress an increase in the flow resistance of the temperature control medium, it is preferable that each of the inlet flow path section 221 and the outlet flow path section 222 is curved significantly toward the first circumferential flow path section 231 after moving away from the top surface of the neck half 200 in the axial direction and reaching a position where it overlaps with at least a part of the connecting flow path section 240 that connects the third circumferential flow path section 233 and the fourth circumferential flow path section 234 in the axial direction.

[0035] In this embodiment, to efficiently cool the mouth 2 side of the preform 1 being molded, it is preferable that the circumferential flow passage section 230 be disposed closer to the molding surface. To prevent uneven cooling in the circumferential direction across the entire mouth 2 side, it is preferable that the connecting flow passage section 240 connecting the circumferential end sides of the circumferential flow passage section 230 be disposed closer to the surface of the parting line PL. However, if the flow passage section 220, including the circumferential flow passage section 230 and the connecting flow passage section 240, is positioned too close to the surface of the neck half 200, resulting in a thin wall, this could impair the durability of the neck half 200. Considering these factors, it is preferable to design the flow passage section 220 disposed inside the neck half 200 so that a clearance of at least 2 mm is secured between the surface of the neck half 200 and the flow passage section 220. Furthermore, the neck half 200 having such a flow path section 220 disposed therein can be produced, for example, by a metal 3D printer, casting, powder metallurgy, etc., but it is easiest and preferable to produce it by a metal 3D printer.

[0036] Finally, the results of the temperature analysis by simulation for the embodiment shown in Figures 4 to 6 are shown. In this simulation, a model was used in which the circumferential flow passage 230 was arranged so as to ensure a clearance of 2 mm between the molding surface, and the diameter of the flow passage 220 was 3.0 mm, the flow passage cross-sectional area S was 7.1 mm. 2 The flow path length L was set to 237.0 mm, and the flow path length L / flow path cross-sectional area S was set to 33.5. In addition, when the flow rate of cooling water was measured by circulating it through the temperature control circuit 210 of the neck half 200 manufactured according to the above settings, the average value was about 2.3 L / min.

[0037] Figure 8 shows the results of an analysis of the mold temperature of the neck half 200 in the area molding the opening end of the mouth portion 2, measuring the ratio of the temperature after temperature control to the initial temperature. Figure 9 shows the results of a similar analysis of the mold temperature of the neck half 200 in the area molding the area between the bead ring 23 and the neck ring 22.

[0038] In the graphs shown in FIGS. 8 and 9, the horizontal axis represents the angle from one surface on the parting line PL, and the vertical axis represents the ratio of the temperature after temperature adjustment to the initial temperature.

[0039] [First Modification] Next, a first modification of the neck half 200 as the molding die according to this embodiment will be described.

[0040] Figure 10 is an oblique view of a first variant of the neck half 200, showing the temperature control circuit 210 through it, Figure 11 is a plan view of the same, and Figure 12 is a side view of the same. In all figures, the temperature control circuit 210 is shown in solid lines, and the outline of the neck half 200 is shown in dashed double-dashed lines.

[0041] In this modification, the inlet flow path portion 221 and the outlet flow path portion 222 are connected to a second circumferential flow path portion 232 disposed at a position farthest from the inlet hole 211 and the outlet hole 212. The flow path portion 220 is configured so that the first circumferential flow path portion 231 disposed at a position closest to the inlet hole 211 and the outlet hole 212 is continuous without being interrupted along the circumferential direction of the neck half 200, so that the temperature control medium introduced through the inlet hole 211 passes through the flow path portion 220 and flows out of the outlet hole 212. Other than these points, the configuration is the same as that of the embodiment shown in FIGS. 4 to 6.

[0042] A temperature analysis was carried out by simulation in the same manner as in the example shown in Figures 4 to 6. In this simulation, a model was used in which the circumferential flow passage 230 was arranged so as to ensure a clearance of 2 mm between the molding surface, and the diameter of the flow passage 220 was 3.0 mm, and the flow passage cross-sectional area S was 7.1 mm. 2 The flow path length L was set to 255.3 mm, and the flow path length L / flow path cross-sectional area S was set to 36.1. The results are shown in Figures 8 and 9. In addition, when the flow rate of cooling water was measured by circulating it through the temperature control circuit 210 of the neck half 200 manufactured according to the above settings, the average value was about 2.0 L / min.

[0043] [Second Modification] Next, a second modification of the neck half 200 as the molding die according to this embodiment will be described.

[0044] Figure 13 is an oblique view of a second variant of the neck half 200, showing the temperature control circuit 210 through it, Figure 14 is a plan view of the same, and Figure 15 is a side view of the same. In all figures, the temperature control circuit 210 is shown in solid lines, and the outline of the neck half 200 is shown in dashed double-dashed lines.

[0045] In this modification, the third circumferential flow path portion 233 and the fourth circumferential flow path portion 234 are separated at a position farther apart in the circumferential direction than in the embodiment shown in Figures 4 to 6, and the connection flow path portion 240 connecting the third circumferential flow path portion 233 and the fourth circumferential flow path portion 234 is located circumferentially outward of the inlet-side connection flow path portion 241 and the outlet-side connection flow path portion 242. To compensate for the resulting reduction in flow path length L, the inlet-side connection flow path portion 241 and the outlet-side connection flow path portion 242 are curved more greatly than in the embodiment shown in Figures 4 to 6. Other than these points, the modification is configured similarly to the embodiment shown in Figures 4 to 6.

[0046] A temperature analysis was carried out by simulation in the same manner as in the example shown in Figures 4 to 6. In this simulation, a model was used in which the circumferential flow passage 230 was arranged so as to ensure a clearance of 2 mm between the molding surface, and the diameter of the flow passage 220 was 3.0 mm, and the flow passage cross-sectional area S was 7.1 mm. 2 The flow path length L was set to 234.0 mm, and the flow path length L / flow path cross-sectional area S was set to 33.1. The results are shown in Figures 8 and 9.

[0047] [Second embodiment] Next, a second embodiment of the present invention will be described. FIG. 16 is a perspective view of the neck half 200 as a molding die according to this embodiment, showing the temperature control circuit 210 through it, FIG. 17 is a plan view of the same, and FIG. 18 is a side view of the same. In all of these figures, the temperature control circuit 210 is shown by a solid line, and the outline of the neck half 200 is shown by a two-dot chain line.

[0048] In this embodiment, (1) a temperature control circuit 210 is provided, which includes an inlet 211 and an outlet 212 that open on the surface of the neck half 200, and a flow path section 220 that is disposed inside the neck half 200 so that the temperature control medium that flows in from the inlet 211 flows out from the outlet 212; (2) a ratio L / S of a flow path length L of the flow path section 220 from the inlet 211 to the outlet 212 to a flow path cross-sectional area S of the flow path section 220 is 40 or less; (3) the flow path section 220 includes a circumferential flow path section 230 that is disposed along the circumferential direction of the molding surface that molds the outer peripheral surface of the mouth portion 2 side of the preform 1, and a circularly curved portion 240 that is disposed along the circumferential direction of the molding surface that molds the outer peripheral surface of the mouth portion 2 side of the preform 1. The present embodiment is common to the first embodiment in that (1) it is preferable that the second embodiment is configured to include a connecting flow path section 240 connected to the circumferential flow path section 230 via a connecting portion, (2) it is preferable that the connecting flow path section 240 is designed so that the radius of curvature R at the flow path center in the arc-shaped curved portion of the connecting flow path section 240 is larger than the flow path radius r of that portion, and (3) it is preferable that the ratio L / Lc of the flow path length L of the flow path section 220 to the maximum length Lc along the circumferential direction of the molding surface excluding the ridge molding portions 21f, 22f, and 23f engraved on the molding surface that molds the outer peripheral surface on the mouth portion 2 side of the preform 1 is 1.9 or more. The details of the components common to the first embodiment are denoted by the same reference numerals and the description of the first embodiment is incorporated, and duplicated description will be omitted.

[0049] This embodiment will be described focusing on the differences from the first embodiment. The flow path section 220 is configured to include a circumferential flow path section 230 arranged along the circumferential direction of the molding surface that molds the outer peripheral surface on the mouth 2 side of the preform 1, a serpentine flow path section 250 that snakes along the circumferential direction of the molding surface that molds the outer peripheral surface on the mouth 2 side of the preform 1, via first and second connecting flow path sections 246, 247 arranged in a staggered manner above and below in the axial direction and an axial connecting section 245 that connects these sections in the axial direction, and a third connecting flow path section 248 that connects the circumferential flow path section 230 and the serpentine flow path section 250 at both circumferential end sides.

[0050] In the illustrated example, when the flow path section 220 is configured in this manner, the circumferential flow path section 230 is disposed continuously and uninterrupted along the circumferential direction of the neck half 200 at a position farthest from the inlet holes 211 and the outlet holes 212, similar to the second circumferential flow path section 232 of the first embodiment, and the serpentine flow path section 250 is disposed axially above the circumferential flow path section 230. In such a configuration, it is preferable to dispose the circumferential flow path section 230, which is continuous and uninterrupted along the circumferential direction of the neck half 200, in correspondence with the portion where the portion between the bead ring 23 and the neck ring 22 is to be molded, in order to efficiently cool the portion between the bead ring 23 and the neck ring 22 while suppressing uneven cooling in the circumferential direction, as in the first embodiment, but this is not limited thereto. Although not specifically shown, like the first circumferential flow path section 231 of the first modified example of the first embodiment, the circumferential flow path section 230 may be arranged so as to be continuous without being interrupted along the circumferential direction of the neck half 200 at a position closest to the inlet hole 211 and the outlet hole 212, and the serpentine flow path section 250 may be arranged axially below it.

[0051] In the illustrated example, the inlet flow passage 221 connected to the inlet hole 211 is connected to the serpentine flow passage 250 at the circumferential center of the neck half 200 via the inlet-side connecting flow passage 241, and the outlet flow passage 222 connected to the outlet hole 212 is connected to the serpentine flow passage 250 at the circumferential center of the neck half 200 via the outlet-side connecting flow passage 242, but this is not limiting. Although not particularly illustrated, like the second circumferential flow passage 232 in the first modified example of the first embodiment, a circumferential flow passage 230 may be disposed at a position farthest from the inlet hole 211 and the outlet hole 212, and the inlet flow passage 221 and the outlet flow passage 222 may be connected to the circumferential flow passage 230. The same applies when the circumferential flow passage 230 is disposed at a position closest to the inlet hole 211 and the outlet hole 212.

[0052] Although not shown in detail, in this embodiment, the circumferential flow path section 230 may be disposed axially below the ridge-forming portion 22f that forms the neck ring 22, and the axially lower side of the serpentine flow path section 250 may be disposed so as to overlap the ridge-forming portion 22f in the axial direction. In this configuration, as described in the first embodiment, one or more portions of the axial connecting portion 245 may be partially curved in an arc shape so that the radius of curvature R at the flow path center is greater than the flow path radius r. This may separate the axially lower side of the serpentine flow path section 250 from the ridge-forming portion 22f, thereby appropriately adjusting the clearance between the axially lower side of the serpentine flow path section 250 and the ridge-forming portion 22f. According to this aspect, even if the axial length of the neck half 200 is insufficient, the circumferential flow path section 230 may be disposed axially below the ridge-forming portion 22f that forms the neck ring 22, thereby ensuring a sufficient flow path length L of the flow path section 220.

[0053] The present invention has been described above by showing preferred embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0054] For example, in the above-described embodiment, an example was given in which the preform 1 was incorporated into an injection mold for molding the preform 1 by injection molding as a mold for molding the outer peripheral surface of the mouth portion 2 side of the preform 1, but this is not limiting. The preform 1 can also be incorporated into a compression mold for molding by compression molding, and in addition to these molding methods, it can be applied to various molding methods such as direct blow molding.

[0055] Furthermore, in the above-described embodiment, an example was given in which the preform 1 was used as the molding target, but this is not limiting. Various molded bodies having a cylindrical portion can be used as the molding target. If the cylindrical portion of the molded body to be molded does not have a shape that causes an undercut, it can be applied without the split mold structure as in the above-described embodiment, and in this case, the temperature control circuit 210 can be designed to extend over the entire circumference of the molding mold. Furthermore, if the entire molded body is cylindrical and is molded using only a pair of male and female molds, it can be applied alone as a male mold or a female mold. [Explanation of symbols]

[0056] 1 Preform (molded body) 10 containers 2 Mouth 21 Threaded part 22 Neck Ring 23 Bead ring 21f, 22f, 23f Projection forming part 200 Neck half (split mold, molding mold) 210 Temperature control circuit 211 Inflow hole 212 Outflow hole 220 Flow path section 221 Inlet flow passage 222 Outlet flow passage 230 Circumferential flow passage 231 first circumferential flow path portion 232 second circumferential flow passage portion 233 Third circumferential flow passage 234 Fourth circumferential flow passage 240 Connection flow path 241 Inlet side connection flow channel 242 Outlet side connection flow channel 245 Axial Connection 246 first connecting channel part, 247 Second connecting channel 248 Third connecting channel 250 Serpentine flow path

Claims

1. A mold for forming a cylindrical portion of a molded body, The molding die has a split structure including a pair of split dies that are split in the radial direction, and each of the split dies independently includes a temperature control circuit including an inlet hole and an outlet hole that open on the surface of the split die, and a flow path portion disposed inside the split die so that the temperature control medium flowing in from the inlet hole flows out from the outlet hole without branching along the way, the flow path section includes circumferential flow path sections arranged in a plurality of rows in the axial direction along the circumferential direction of the molding surface that molds the molded body, a connecting flow path section that connects circumferential ends of the circumferential flow path sections that are adjacent in the axial direction, an inflow flow path section that is connected to the inflow hole, and an outflow flow path section that is connected to the outflow hole, the inlet flow passage portion and the outlet flow passage portion are each connected at a circumferential center portion of the split mold to a first circumferential flow passage portion disposed closest to the inlet hole and the outlet hole or a second circumferential flow passage portion disposed farthest from the inlet hole and the outlet hole among the circumferential flow passage portions arranged in a plurality of rows in the axial direction, and the second circumferential flow passage portion or the first circumferential flow passage portion is continuous without being interrupted along the circumferential direction of the split mold, a third circumferential flow path portion and a fourth circumferential flow path portion are arranged side by side in the axial direction between the first circumferential flow path portion and the second circumferential flow path portion, the third circumferential flow path portion and the fourth circumferential flow path portion are separated from each other at a circumferential center portion of the split mold and are connected to each other via the connecting flow path portion, the third circumferential flow path portion is connected to the first circumferential flow path portion via the connecting flow path portion at both circumferential end sides, and the fourth circumferential flow path portion is connected to the second circumferential flow path portion via the connecting flow path portion at both circumferential end sides, A molding die characterized in that a ratio L / S of a flow path length L of the flow path portion from the inlet hole to the outlet hole to a flow path cross-sectional area S of the flow path portion is 40 or less.

2. The molding die according to claim 1 , wherein the connecting flow path portion is connected to the circumferential flow path portion via a portion curved in an arc shape.

3. 3. The mold according to claim 2, wherein the radius of curvature at the center of the arc-shaped curved portion of the connection flow path portion is larger than the flow path radius at that portion.

4. 4. The mold according to claim 1, wherein a ratio L / Lc of a flow path length L of the flow path portion from the inlet hole to the outlet hole to a maximum length Lc along the circumferential direction of the molding surface excluding the protrusion molding portion engraved on the molding surface is 1.9 or more.

5. The inlet flow passage portion is connected to the first circumferential flow passage portion or the second circumferential flow passage portion via an inlet side connecting flow passage portion curved in an arc shape, The molding die according to any one of claims 1 to 4, wherein the outlet flow path portion is connected to the first circumferential flow path portion or the second circumferential flow path portion via an outlet-side connecting flow path portion that is curved in an arc shape.

6. 6. The molding die according to claim 5, wherein the inlet flow path portion and the outlet flow path portion are connected to the first circumferential flow path portion, extend from the inlet hole and the outlet hole, respectively, in a curved manner toward the first circumferential flow path portion, and are arranged so as to overlap in the axial direction with at least a portion of the connecting flow path portion that connects the third circumferential flow path portion and the fourth circumferential flow path portion.

7. The mold according to any one of claims 1 to 6, wherein the second circumferential flow path portion is disposed in correspondence with a portion of the molding surface having a maximum length along the circumferential direction, excluding a protrusion molding portion engraved on the molding surface.

8. 8. The mold according to claim 7, wherein the molded body is a cylindrical preform with a bottom for blow molding a synthetic resin container, and a threaded portion, a bead ring, and a neck ring are molded in this order in the axial direction from the open end side at the mouth of the preform by a protrusion molding portion engraved on the molding surface, and the second circumferential flow path portion is disposed corresponding to the portion to be molded between the bead ring and the neck ring.

9. The molded body is a bottomed cylindrical preform for blow molding a synthetic resin container, and the mold according to any one of claims 1 to 8 molds the outer peripheral surface of the mouth side of the preform.

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