Gate insert, fixing unit, and method for manufacturing a preform

Abstract

To provide a gate insert in which molding defects are less likely to occur on a main body of a preform, a fixing unit, and a manufacturing method of a preform.SOLUTION: A gate insert 100 constitutes a fixed unit for molding a preform. The gate insert 100 has a projection molding unit 200 corresponding to a projection on a bottom of the preform. The projection molding unit 200 includes a restraining unit 220 configured to prevent movement of a cold slug.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The technical field of the present invention relates to a gate insert, a fixing unit, and a method for manufacturing a preform.

Background Art

[0002] A preform is formed, for example, by injection molding. Patent Document 1 describes an example of a conventional preform.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the forming process of the preform, cold slugs may be formed in the gate insert, and molding defects related to the main body of the preform may occur due to the cold slugs.

Means for Solving the Problems

[0005] The gate insert according to the present invention is a gate insert of a fixing unit for forming a preform, and includes a protrusion forming portion corresponding to a protrusion at the bottom of the preform, and the protrusion forming portion includes a restricting portion configured to prevent the movement of cold slugs. According to the above gate insert, since the movement of the cold slugs is prevented by the restricting portion, it is difficult for the cold slugs to move into the molding space of the fixing unit corresponding to the main body of the preform. Therefore, molding defects related to the main body of the preform are less likely to occur.

[0006] In an example of the gate insert, the restricting portion is configured to make one revolution around the central axis of the gate insert. According to the gate insert, the effect of preventing the movement of cold slag is enhanced.

[0007] In an example of the gate insert, the restricting portion is provided near the gate land in a direction parallel to the central axis of the gate insert. According to the gate insert, cold slag is likely to stay in a portion close to the gate land.

[0008] In an example of the gate insert, the restricting portion is configured to protrude with respect to the base portion of the protrusion forming portion, and includes a first side surface, a second side surface, and an intermediate surface. The first side surface is located between the intermediate surface and the gate land, and the second side surface is located between the intermediate surface and the base portion. According to the gate insert, when cold slag is in contact with the first side surface, the cold slag is likely to stay.

[0009] In an example of the gate insert, the intermediate surface is a curved surface, and the radius of the arc indicating the intermediate surface is included in the range of 2 mm or less. According to the gate insert, the effect of preventing the movement of cold slag is easily obtained.

[0010] In an example of the gate insert, the angle indicating the inclination of the first side surface with respect to the radial direction of the gate insert is included in the range of 30° or more. According to the gate insert, the effect of preventing the movement of cold slag is easily obtained.

[0011] In an example of the gate insert, the angle indicating the inclination of the first side surface with respect to the radial direction of the gate insert is included in the range of 90° or less. According to the gate insert, the protrusion of the preform is likely to be separated from the protrusion forming portion.

[0012] The fixing unit according to the present invention includes the gate insert. According to the above fixing unit, it is less likely that a molding defect occurs in the main body of the preform.

[0013] The method for manufacturing a preform according to the present invention includes a molding step of molding a preform using the above fixing unit. According to the above manufacturing method, it is less likely that a molding defect occurs in the main body of the preform.

Effects of the Invention

[0014] According to the gate insert, the fixing unit, and the method for manufacturing a preform of the present invention, it is less likely that a molding defect occurs in the main body of the preform.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0016] (First Embodiment) FIG. 1 shows an example of a preform P10. FIG. 3 shows an example of an injection mold 10. The preform P10 is manufactured, for example, by the injection mold 10. The preform P10 is used, for example, in the manufacture of plastic bottles. In the description of the preform P10 and the injection mold 10, the X1 direction, X2 direction, Y1 direction, Y2 direction, Z1 direction, and Z2 direction are referred to.

[0017] The X1 direction and the X2 direction are parallel to the X axis. The X1 direction is opposite to the X2 direction. The X direction is a general term for the X1 direction and the X2 direction. The Y1 direction and the Y2 direction are parallel to the Y axis. The Y1 direction is opposite to the Y2 direction. The Y direction is a general term for the Y1 direction and the Y2 direction. The Z1 direction and the Z2 direction are parallel to the Z axis. The Z1 direction is opposite to the Z2 direction. The Z direction is a general term for the Z1 direction and the Z2 direction. Among the cross-sections of the preform P10 and the injection mold 10, a cross-section parallel to the X axis and the Y axis is referred to as a reference cross-section.

[0018] FIG. 1 shows a reference cross-section of the preform P10. The axial direction of the preform P10 is parallel to the central axis of the preform P10. The axial direction of the preform P10 is parallel to the X direction. The radial direction of the preform P10 is perpendicular to the axial direction of the preform P10. The configuration of the preform P10 can be arbitrarily selected. The configuration of the preform P10 is not limited to the illustrated configuration. The preform P10 includes a main body P100. The main body P100 includes, for example, a bottom P110, a body portion P120, and an opening P130.

[0019] The main body P100 is a cylinder. A space is formed inside the main body P100. The space inside the main body P100 is referred to as the main body space P101. The body portion P120 constitutes a main part of the main body P100. The body portion P120 is divided, for example, into a main body part P121 and a sub-body part P122. The outer diameter of the main body part P121 is constant. The auxiliary body part P122 is located in the X2 direction with respect to the main body part P121. The auxiliary body part P122 has a taper. The outer diameter of the auxiliary body part P122 increases as it advances in the X2 direction.

[0020] The bottom part P110 is located in the X1 direction with respect to the body part P120. The shape of the bottom part P110 is a hemisphere. The bottom part P110 includes a tip part P111. The tip part P111 of the bottom part P110 corresponds to the top of the hemisphere. The opening part P130 is located in the X2 direction with respect to the body part P120. The opening part P130 includes an opening end P131. The main body space P101 opens to the opening end P131.

[0021] The opening part P130 includes a male thread P132 and a support ring P133. The male thread P132 and the support ring P133 are provided on the outer periphery of the opening part P130. The male thread P132 is located in the X1 direction with respect to the opening end P131. The support ring P133 is located in the X1 direction with respect to the male thread P132.

[0022] Refer to Figure 2. Figure 2 shows an enlarged view of the bottom part P110 of the preform P10 shown in Figure 1. The preform P10 includes a protrusion P200. The protrusion P200 is provided at the tip part P111 of the bottom part P110. The form of the protrusion P200 is a short gate.

[0023] The protrusion P200 protrudes in the X1 direction with respect to the tip part P111 of the bottom part P110. The central axis of the protrusion P200 is coaxial with the central axis of the preform P10. The shape of the protrusion P200 is defined by, for example, a basic solid. The basic solid corresponding to the protrusion P200 is a column. The side surface of the basic solid is a curved surface. The top surface and the bottom surface of the basic solid are flat surfaces. The outer diameter of the basic solid decreases as it advances in the X1 direction.

[0024] In the reference cross-section, the basic solid is shown by a curve LP1, a curve LP2, a line segment LP3, and a line segment LP4. The curve LP1 shows the side surface of the base solid. The curve LP1 is shown by the solid line curve LP11 and the two-dot chain line curve LP12. The curve LP1 is an arc. The center of the arc is defined outside the base solid.

[0025] The curve LP2 shows the side surface of the base solid. The curve LP2 is shown by the solid line curve LP21 and the two-dot chain line curve LP22. The curve LP2 is an arc. The center of the arc is defined outside the base solid. The line segment LP3 shows the top surface of the base solid. The line segment LP3 is shown by the solid line line segment LP31 and the two-dot chain line line segments LP32, LP33. The two-dot chain line line segment LP4 shows the bottom surface of the base solid.

[0026] The protrusion P200 includes the side surface P201 and the top surface P202. The side surface P201 is defined by the side surface of the base solid. The top surface P202 is defined by the top surface of the base solid. The protrusion P200 includes the base portion P210, the concave portion P220, the top portion P230, and the annular portion P240. The base portion P210 is located in the X1 direction with respect to the bottom portion P110 of the preform P10. The concave portion P220 is located in the X1 direction with respect to the base portion P210. The top portion P230 is located in the X1 direction with respect to the concave portion P220. The annular portion P240 is located in the X1 direction with respect to the top portion P230.

[0027] The base portion P210 is connected to the tip portion P111 of the bottom portion P110 of the preform P10. The shape of the base portion P210 corresponds to the shape of the base solid. The outer diameter of the base portion P210 becomes smaller as it progresses in the X1 direction.

[0028] The base portion P210 includes the side surface P211. The side surface P211 of the base portion P210 constitutes a part of the side surface P201 of the protrusion P200. The side surface P211 of the base portion P210 is defined by the side surface of the base solid. The solid line curves LP11, LP21 show the side surface P211 of the base portion P210. The side surface P211 of the base portion P210 is a curved surface. In the reference cross-section, the side surface P211 of the base portion P210 is shown by an arc. The center of the arc is defined outside the protrusion P200.

[0029] The recessed portion P220 is configured to be recessed with respect to the base solid. The recessed portion P220 includes a side surface P221. The side surface P221 of the recessed portion P220 constitutes a part of the side surface P201 of the protrusion P200. The side surface P221 of the recessed portion P220 does not overlap with the side surface of the base solid. The side surface P221 of the recessed portion P220 is located radially inward of the preform P10 with respect to the side surface of the base solid. The side surface P221 of the recessed portion P220 includes a flat surface and a curved surface.

[0030] The top portion P230 includes a side surface P231. The side surface P231 of the top portion P230 constitutes a part of the side surface P201 of the protrusion P200. The side surface P231 of the top portion P230 is a curved surface. The side surface P231 of the top portion P230 does not overlap with the side surface of the base solid. The side surface P231 of the top portion P230 is located radially inward of the preform P10 with respect to the side surface of the base solid.

[0031] The top portion P230 includes a top surface P232. The top surface P232 of the top portion P230 constitutes the top surface P202 of the protrusion P200. The top surface P232 of the top portion P230 is a flat surface. The top surface P232 of the top portion P230 overlaps with the top surface of the base solid. The solid line segment LP31 indicates the top surface P232 of the top portion P230.

[0032] The annular portion P240 is connected to the outer peripheral portion of the top portion P230. The annular portion P240 includes an inner peripheral surface P241. The inner peripheral surface P241 of the annular portion P240 defines the space of the annular portion P240.

[0033] Refer to FIG. 3. FIG. 3 shows a reference cross-section of a part of the injection mold 10. The injection mold 10 forms the preform P10 from a resin material. The configuration of the injection mold 10 can be arbitrarily selected. The configuration of the injection mold 10 is not limited to the illustrated configuration.

[0034] The supply method of the resin material in the injection mold 10 is, for example, the hot runner type. The injection mold 10 includes, for example, a hot runner unit 20 and a molding unit 30. The hot runner unit 20 supplies the molten resin material to the molding unit 30. The molding unit 30 forms the preform P10 from the molten resin material. The hot runner unit 20 includes, for example, a heating manifold, a nozzle tip 21, a heater 22, a heat insulator 23, and a valve stem 24. The heat insulator 23 may also be referred to as a nozzle tip insulator.

[0035] The nozzle tip 21 is coupled to the heating manifold. The central axis of the nozzle tip 21 is parallel to the X axis. A flow path 21A is formed inside the nozzle tip 21. The flow path 21A of the nozzle tip 21 is connected to the flow path of the heating manifold. The resin material flows from the flow path of the heating manifold into the flow path 21A of the nozzle tip 21. The nozzle tip 21 includes a tip portion 21B. The tip portion 21B of the nozzle tip 21 includes an opening 21C. An injection hole 21D is formed in the opening 21C. The injection hole 21D communicates with the flow path 21A of the nozzle tip 21.

[0036] The heater 22 is provided on the outer periphery of the nozzle tip 21. The heater 22 heats the nozzle tip 21. The heat of the heater 22 is transmitted to the resin material through the nozzle tip 21. The heat insulator 23 is provided on the outer periphery of the heater 22. The heat insulator 23 prevents the transfer of heat between the heater 22 and the molding unit 30.

[0037] A part of the valve stem 24 is disposed in the flow path 21A of the nozzle tip 21. The central axis of the valve stem 24 is parallel to the X axis. The valve stem 24 is movable in the X direction with respect to the nozzle tip 21. The valve stem 24 includes a tip portion 24A. The tip portion 24A of the valve stem 24 is configured to be able to pass through the injection hole 21D of the nozzle tip 21.

[0038] The configuration of the forming unit 30 can be arbitrarily selected. The configuration of the forming unit 30 is not limited to the exemplified configuration. The forming unit 30 includes, for example, a fixed unit 40, a neck ring 60, and a movable unit 70. The fixed unit 40 is located in the X2 direction with respect to the hot runner unit 20. The neck ring 60 is located in the X2 direction with respect to the fixed unit 40. The movable unit 70 is located in the X2 direction with respect to the neck ring 60.

[0039] The configuration of the fixed unit 40 can be arbitrarily selected. The configuration of the fixed unit 40 is not limited to the exemplified configuration. The fixed unit 40 includes, for example, a plate, a gate insert 100, and a cavity 50. The gate insert 100 is attached to the plate. The gate insert 100 is configured to be detachable from the plate. The cavity 50 is located in the X2 direction with respect to the gate insert 100. The cavity 50 is attached to the plate. The cavity 50 is configured to be detachable from the plate.

[0040] Refer to FIGS. 4 and 5. FIGS. 4 and 5 show enlarged views of the gate insert 100 and the like shown in FIG. 3. The configuration of the gate insert 100 can be arbitrarily selected. The configuration of the gate insert 100 is not limited to the exemplified configuration. Examples of the material of the gate insert 100 include ferrous materials or non-ferrous materials. Examples of ferrous materials include steel. Examples of steel include pre-hardened steel, quenched and tempered steel, stainless steel, and age-hardened steel.

[0041] The axial direction of the gate insert 100 is parallel to the central axis of the gate insert 100 (hereinafter referred to as "gate central axis LC"). The axial direction of the gate insert 100 is parallel to the X direction. The radial direction of the gate insert 100 is orthogonal to the axial direction of the gate insert 100. The gate insert 100 includes a first end face 100A and a second end face 100B. The first end face 100A is located in the X1 direction with respect to the center of the gate insert 100 in the X direction. The second end face 100B is located in the X2 direction with respect to the center of the gate insert 100 in the X direction.

[0042] The gate insert 100 includes a placement portion 110. A space is formed in the placement portion 110. The space in the placement portion 110 is referred to as a placement space 110A. The placement portion 110 includes an inner surface 111. The inner surface 111 defines the placement space 110A. The placement space 110A opens to the second end face 100B of the gate insert 100.

[0043] The tip portion 21B of the nozzle tip 21 is disposed in the placement space 110A. The heat insulator 23 is disposed in the placement space 110A. The heat insulator 23 is disposed between the tip portion 21B of the nozzle tip 21 and the inner surface 111 of the placement portion 110. The heat insulator 23 prevents heat transfer between the tip portion 21B of the nozzle tip 21 and the gate insert 100.

[0044] The gate insert 100 includes a gate land 120. The gate land 120 is located in the X2 direction with respect to the placement portion 110. A flow path 120A is formed in the gate land 120. The gate land 120 includes an inner surface 121. The inner surface 121 defines the flow path 120A of the gate land 120.

[0045] The flow path 120A includes an inlet 120B. The inlet 120B is located in the X1 direction with respect to the center of the flow path 120A in the X direction. The injection hole 21D of the nozzle tip 21 is connected to the inlet 120B. The flow path 120A includes a gate 120C. The gate 120C is located in the X2 direction with respect to the center of the flow path 120A in the X direction.

[0046] The gate insert 100 includes a molding portion 130. The molding portion 130 is located in the X2 direction with respect to the gate land 120. A space is formed in the molding portion 130. The space in the molding portion 130 is referred to as a first internal space S10. The forming part 130 includes an inner surface 131. The inner surface 131 defines a first internal space S10. The gate 120C is connected to the first internal space S10. The first internal space S10 opens to the second end surface 100B of the gate insert 100.

[0047] The first internal space S10 corresponds to the bottom P110 and the protrusion P200 of the preform P10. The inner surface 131 of the forming part 130 corresponds to the outer surface of the bottom P110 of the preform P10 and the outer surface of the protrusion P200. The forming part 130 is divided into a bottom forming part 140 and a protrusion forming part 200. The first internal space S10 is divided into a bottom space S11 and a protrusion space S12. The inner surface 131 of the forming part 130 is divided into an inner surface 141 and an inner surface 201.

[0048] The bottom space S11 is a space formed in the bottom forming part 140. The bottom space S11 corresponds to the bottom P110 of the preform P10. The bottom forming part 140 includes an inner surface 141. The inner surface 141 defines the bottom space S11. The inner surface 141 corresponds to the outer surface of the bottom P110 of the preform P10.

[0049] The protrusion space S12 is a space formed in the protrusion forming part 200. The protrusion space S12 corresponds to the protrusion P200 of the preform P10. The protrusion forming part 200 includes an inner surface 201. The inner surface 201 defines the protrusion space S12. The inner surface 201 of the protrusion forming part 200 corresponds to the outer surface of the protrusion P200 of the preform P10.

[0050] Refer to FIGS. 4 and 5. The tip 24A of the valve stem 24 enters and exits with respect to the flow path 120A of the gate land 120. As the position of the valve stem 24 in the X direction, for example, an open position or a closed position is selected. FIG. 4 shows a state where the position of the valve stem 24 is the open position. FIG. 5 shows a state where the position of the valve stem 24 is the closed position.

[0051] When the position of the valve stem 24 is in the open position, for example, the following state can be observed. The tip 24A of the valve stem 24 is disposed in the flow path 21A of the nozzle tip 21. The tip 24A of the valve stem 24 is positioned in the X1 direction with respect to the injection hole 21D of the nozzle tip 21.

[0052] The injection hole 21D of the nozzle tip 21 is opened. The flow path 120A of the gate land 120 is opened. The flow path 21A of the nozzle tip 21 is connected to the flow path 120A of the gate land 120 via the injection hole 21D. The resin material flows in the order of the flow path 21A of the nozzle tip 21, the injection hole 21D, the flow path 120A of the gate land 120, and the first internal space S10.

[0053] In a state where the position of the valve stem 24 is in the open position, when the valve stem 24 moves in the X2 direction, the position of the valve stem 24 is changed to the closed position. In a state where the position of the valve stem 24 is in the closed position, when the valve stem 24 moves in the X1 direction, the position of the valve stem 24 is changed to the open position.

[0054] When the position of the valve stem 24 is in the closed position, for example, the following state can be observed. The tip 24A of the valve stem 24 is disposed in the injection hole 21D of the nozzle tip 21 and the flow path 120A of the gate land 120. The injection hole 21D of the nozzle tip 21 and the flow path 120A of the gate land 120 are closed by the valve stem 24. The flow path 21A of the nozzle tip 21 is not connected to the flow path 120A of the gate land 120.

[0055] Referring to FIG. 3, the configuration of the cavity 50 can be arbitrarily selected. The configuration of the cavity 50 is not limited to the illustrated configuration. Examples of the material of the cavity 50 include ferrous materials or non-ferrous materials. Examples of ferrous materials include steel. Examples of steel include pre-hardened steel, quenched and tempered steel, stainless steel, and age-hardened steel.

[0056] The axial direction of the cavity 50 is parallel to the central axis of the cavity 50. The axial direction of the cavity 50 is parallel to the X direction. The radial direction of the cavity 50 is orthogonal to the axial direction of the cavity 50. The cavity 50 includes a first end face 50A and a second end face 50B. The first end face 50A is located in the X1 direction with respect to the center of the cavity 50 in the X direction. The second end face 50B is located in the X2 direction with respect to the center of the cavity 50 in the X direction.

[0057] A space is formed inside the cavity 50. The space inside the cavity 50 is referred to as the second internal space S20. The cavity 50 includes an inner surface 51. The inner surface 51 defines the second internal space S20. The second internal space S20 opens to the first end face 50A of the cavity 50. The second internal space S20 opens to the second end face 50B of the cavity 50. The second internal space S20 is connected to the first internal space S10. The second internal space S20 corresponds to the body main part P121 of the body part P120 of the preform P10.

[0058] Referring to FIG. 3. The configuration of the neck ring 60 can be arbitrarily selected. The configuration of the neck ring 60 is not limited to the illustrated configuration. The neck ring 60 is located in the X2 direction with respect to the cavity 50. The neck ring 60 is configured to be fitted to the cavity 50. The neck ring 60 is configured to be movable in the X direction with respect to the cavity 50.

[0059] Examples of the material of the neck ring 60 include ferrous materials or non-ferrous materials. Examples of ferrous materials include steel. Examples of steel include pre-hardened steel, quenched and tempered steel, stainless steel, and age-hardened steel. The axial direction of the neck ring 60 is parallel to the central axis of the neck ring 60. The axial direction of the neck ring 60 is parallel to the X direction. The radial direction of the neck ring 60 is orthogonal to the axial direction of the neck ring 60.

[0060] The neck ring 60 is configured to be divisible into a plurality of ring elements. The plurality of ring elements include, for example, a first ring element and a second ring element. The first ring element constitutes one half of the neck ring 60. The second ring element constitutes the other half of the neck ring 60. Each ring element is configured to fit together. Each ring element is configured to be movable inward and outward in the radial direction of the neck ring 60.

[0061] The neck ring 60 is connected to a first actuator. The first actuator moves the neck ring 60 in the X direction. The first actuator moves each ring element in the radial direction of the neck ring 60. As a state of the neck ring 60, for example, a fitting state or a separated state is selected. The fitting state of the neck ring 60 is a state in which each ring element is fitted together. The separated state of the neck ring 60 is a state in which each ring element is located apart and does not fit together.

[0062] When the state of the neck ring 60 is the fitting state, the state of the neck ring 60 is changed to the separated state by each ring element moving outward in the radial direction of the neck ring 60. When the state of the neck ring 60 is the separated state, the state of the neck ring 60 is changed to the fitting state by each ring element moving inward in the radial direction of the neck ring 60.

[0063] The neck ring 60 includes a first end face 60A and a second end face 60B. The first end face 60A is located in the X1 direction with respect to the center of the neck ring 60 regarding the X direction. The second end face 60B is located in the X2 direction with respect to the center of the neck ring 60 regarding the X direction.

[0064] A space is formed inside the neck ring 60 in the fitting state. The internal space of the neck ring 60 is referred to as a third internal space S30. The neck ring 60 includes an inner surface 61. The inner surface 61 defines the third internal space S30. The third internal space S30 opens to the first end face 60A of the neck ring 60. The third internal space S30 opens to the second end face 60B of the neck ring 60. The third internal space S30 is connected to the second internal space S20. The third internal space S30 corresponds to the body sub - part P122 and the opening P130 of the body part P120 of the preform P10.

[0065] As the position of the neck ring 60 in the X - direction, for example, the molding position or the take - out position is selected. When the state of the neck ring 60 is the fitting state, the position of the neck ring 60 is changed. When the position of the neck ring 60 is the take - out position, the state of the neck ring 60 is changed.

[0066] When the position of the neck ring 60 is the take - out position, by moving the neck ring 60 in the X1 - direction, the position of the neck ring 60 is changed to the molding position. When the position of the neck ring 60 is the molding position, by moving the neck ring 60 in the X2 - direction, the position of the neck ring 60 is changed to the take - out position.

[0067] When the position of the neck ring 60 is the molding position, for example, the following situation can be observed. The neck ring 60 fits into the cavity 50. The third internal space S30 is connected to the second internal space S20. When the position of the neck ring 60 is the take - out position, for example, the following situation can be observed. The neck ring 60 is located at a position away from the cavity 50 in the X2 - direction. The third internal space S30 is not connected to the second internal space S20.

[0068] Referring to FIG. 3. The configuration of the movable unit 70 can be arbitrarily selected. The configuration of the movable unit 70 is not limited to the illustrated configuration. The movable unit 70 includes, for example, a core 71, a lock ring 72, and a movable plate 73. The movable unit 70 is configured to be movable in the X - direction with respect to the cavity 50 and the neck ring 60.

[0069] The core 71 is divided into a first part 71A and a second part 71B. The first part 71A corresponds to the body space P101 of the preform P10. The second part 71B is located in the X2 direction with respect to the first part 71A. The second part 71B is fixed to the movable plate 73. The lock ring 72 is located in the X2 direction with respect to the neck ring 60. The lock ring 72 is configured to be fitted to the neck ring 60. The lock ring 72 is fixed to the second part 71B of the core 71. The movable plate 73 is located in the X2 direction with respect to the core 71 and the lock ring 72. The movable plate 73 is connected to the second actuator. The second actuator moves the movable plate 73 in the X direction.

[0070] As the position of the movable unit 70 in the X direction, for example, a molding position or an ejection position is selected. When the position of the movable unit 70 is the ejection position, the position of the movable unit 70 is changed to the molding position by moving the movable unit 70 in the X1 direction. When the position of the movable unit 70 is the molding position, the position of the movable unit 70 is changed to the ejection position by moving the movable unit 70 in the X2 direction.

[0071] When the position of the neck ring 60 is the molding position and the position of the movable unit 70 is the molding position, for example, the following state can be observed. The first part 71A of the core 71 is disposed in the first internal space S10, the second internal space S20, and the third internal space S30. The lock ring 72 is fitted to the neck ring 60. A molding space SM is formed between the inner surface 131 of the molding part 130 of the gate insert 100, the inner surface 51 of the cavity 50, and the inner surface 61 of the neck ring 60 and the core 71. The molding space SM corresponds to the preform P10.

[0072] When the position of the movable unit 70 is the take-out position, for example, the following state can be observed. The first part 71A of the core 71 is not disposed in the first internal space S10, the second internal space S20, and the third internal space S30. The lock ring 72 is located at a position away from the neck ring 60 in the X2 direction.

[0073] The method for manufacturing the preform P10 includes a molding process. One cycle of the molding process includes, for example, a mold clamping process, an injection process, a cooling process, and a mold opening process. The mold clamping process is performed after the previous molding process. The injection process is performed after the mold clamping process. The cooling process is performed after the injection process. The mold opening process is performed after the cooling process.

[0074] In the mold clamping process, for example, the following state can be observed. The position of the valve stem 24 is the closed position. Each ring element of the neck ring 60 moves inward in the radial direction of the neck ring 60. The state of the neck ring 60 is changed from the separated state to the fitted state. The neck ring 60 moves in the X1 direction. The position of the neck ring 60 is changed from the take-out position to the molding position. The neck ring 60 fits into the cavity 50. The movable unit 70 moves in the X1 direction. The position of the lock ring 72 is changed from the take-out position to the molding position. The lock ring 72 fits into the neck ring 60. The first part 71A of the core 71 is disposed in the first internal space S10, the second internal space S20, and the third internal space S30.

[0075] In the injection process, for example, the following state can be observed. The valve stem 24 moves in the X1 direction. The position of the valve stem 24 is changed from the closed position to the open position. The injection hole 21D of the nozzle tip 21 and the flow path 120A of the gate land 120 are opened. The resin material staying in the flow path 21A of the nozzle tip 21 flows into the molding space SM through the injection hole 21D of the nozzle tip 21 and the flow path 120A of the gate land 120. The molding space SM is filled with the resin material. The valve stem 24 moves in the X2 direction. The position of the valve stem 24 is changed from the open position to the closed position. The injection hole 21D of the nozzle tip 21 and the flow path 120A of the gate land 120 are closed by the tip portion 24A of the valve stem 24.

[0076] In the cooling process, for example, the following can be observed. The resin material staying in the molding space SM is cooled by the fixed unit 40, the neck ring 60, and the movable unit 70. The cooling process continues until a predetermined cooling time elapses.

[0077] In the mold opening process, for example, the following can be observed. The movable unit 70 moves in the X2 direction. The position of the lock ring 72 is changed from the molding position to the take-out position. The first portion 71A of the core 71 is disposed outside the first internal space S10, the second internal space S20, and the third internal space S30. The neck ring 60 moves in the X2 direction. The position of the neck ring 60 is changed from the molding position to the take-out position. The preform P10 moves in the X2 direction together with the neck ring 60. The preform P10 is separated from the gate insert 100 and the cavity 50. Each ring element of the neck ring 60 moves radially outward of the neck ring 60. The state of the neck ring 60 is changed from the fitting state to the separated state. The preform P10 is separated from the neck ring 60.

[0078] Refer to FIG. 6. FIG. 6 shows an enlarged view of a part centered on the molding portion 130 of the gate insert 100 shown in FIG. 3. The configuration of the bottom molding portion 140 can be arbitrarily selected. The configuration of the bottom molding portion 140 is not limited to the illustrated configuration. The shape of the bottom space S11 of the bottom molding portion 140 is defined by, for example, a basic solid. The basic solid corresponding to the bottom space S11 is a hemisphere. In the reference cross section, the basic solid is shown by the curve LQ1 and the line segment LQ2.

[0079] The curve LQ1 shows the hemispherical surface of the base solid. The curve LQ1 is shown by the solid-line curves LQ11, LQ12, and the two-dot chain-line curve LQ13. The curve LQ1 is an arc. The center of the arc is determined on the cutting plane of the base solid. The line segment LQ2 shows the cutting plane of the base solid. The shape of the inner surface 141 of the bottom forming portion 140 corresponds to the shape of the bottom space S11. In the reference cross-section, the inner surface 141 of the bottom forming portion 140 is shown by the curves LQ11, LQ12.

[0080] Refer to FIGS. 7 and 8. FIG. 7 shows an enlarged view of the protrusion forming portion 200 shown in FIG. 6. FIG. 8 shows an enlarged view of a part of the protrusion forming portion 200 shown in FIG. 7. The configuration of the protrusion forming portion 200 can be arbitrarily selected. The configuration of the protrusion forming portion 200 is not limited to the exemplified configuration.

[0081] The shape of the protrusion space S12 of the protrusion forming portion 200 is defined, for example, by the base solid. The base solid corresponding to the protrusion space S12 is a column. The side surface of the base solid is a curved surface. The top surface and the bottom surface of the base solid are planes. The outer diameter of the base solid becomes smaller as it progresses in the X1 direction. In the reference cross-section, the base solid is shown by the curve LR1, the curve LR2, the line segment LR3, and the line segment LR4.

[0082] The curve LR1 shows the side surface of the base solid. The curve LR1 is shown by the solid-line curve LR11 and the two-dot chain-line curve LR12. The curve LR1 is an arc. The center of the arc is determined outside the base solid. The curve LR2 shows the side surface of the base solid. The curve LR2 is shown by the solid-line curve LR21 and the two-dot chain-line curve LR22. The curve LR2 is an arc. The center of the arc is determined outside the base solid. The line segment LR3 shows the top surface of the base solid. The line segment LR3 is shown by the solid-line line segment LR31 and the two-dot chain-line line segments LR32, LR33. The two-dot chain-line line segment LR4 shows the bottom surface of the base solid.

[0083] The protruding forming portion 200 includes an inner surface 201. The side surface P201 is defined by the side surface of the base solid. The top surface P202 is defined by the top surface of the base solid. The protruding forming portion 200 includes a base portion 210, a restricting portion 220, and a top portion 230. The base portion 210 is located in the X1 direction with respect to the bottom forming portion 140. The restricting portion 220 is located in the X1 direction with respect to the base portion 210. The top portion 230 is located in the X1 direction with respect to the restricting portion 220.

[0084] The base portion 210 is connected to the bottom forming portion 140. The shape of the base portion 210 corresponds to the shape of the base solid. The inner diameter of the base portion 210 becomes smaller as it progresses in the X1 direction. The base portion 210 includes an inner surface 211. The inner surface 211 of the base portion 210 constitutes a part of the side surface P201 of the protrusion P200. The inner surface 211 of the base portion 210 is defined by the side surface of the base solid. The solid lines LR11 and LR21 indicate the inner surface 211 of the base portion 210. The inner surface 211 of the base portion 210 is a curved surface. In the reference cross-section, the inner surface 211 of the base portion 210 is shown by an arc. The center of the arc is defined outside the protrusion space S12.

[0085] The restricting portion 220 is configured to prevent the movement of the cold slag C (see FIG. 9) from the protrusion space S12 to the bottom space S11. The restricting portion 220 is configured to include a stepped portion on which the cold slag C catches. The restricting portion 220 is configured to be recessed with respect to the base solid. The restricting portion 220 is configured to protrude radially inward of the gate insert 100 with respect to the base portion 210.

[0086] The restricting portion 220 is provided closer to the gate land 120 in the X direction. The restricting portion 220 is configured to make one full turn around the gate central axis LC. The restricting portion 220 includes an inner surface 221. The inner surface 221 of the restricting portion 220 constitutes a part of the inner surface 201 of the protruding forming portion 200. The inner surface 221 of the restricting portion 220 does not overlap with the side surface of the base solid.

[0087] The inner surface 221 of the regulating part 220 is located radially inward of the gate insert 100 with respect to the side surface of the base solid. The inner surface 221 of the regulating part 220 is configured to protrude radially inward of the gate insert 100 with respect to the inner surface 211 of the base part 210. The inner surface 221 of the regulating part 220 includes a first side surface 221A, a second side surface 221B, and an intermediate surface 221C.

[0088] The first side surface 221A of the regulating part 220 is located between the intermediate surface 221C of the regulating part 220 and the inner surface 121 of the gate land 120. The first side surface 221A of the regulating part 220 is connected to the intermediate surface 221C of the regulating part 220. The first side surface 221A of the regulating part 220 is a plane. The portion of the regulating part 220 corresponding to the first side surface 221A has a taper. The inner diameter of the portion of the regulating part 220 corresponding to the first side surface 221A increases as it advances in the X2 direction. The first side surface 221A of the regulating part 220 is inclined with respect to the gate central axis LC.

[0089] The second side surface 221B of the regulating part 220 is located between the intermediate surface 221C of the regulating part 220 and the inner surface 211 of the base part 210. The second side surface 221B of the regulating part 220 is connected to the intermediate surface 221C of the regulating part 220. The second side surface 221B of the regulating part 220 is a plane. The portion of the regulating part 220 corresponding to the second side surface 221B has a taper. The inner diameter of the portion of the regulating part 220 corresponding to the second side surface 221B increases as it advances in the X2 direction. The second side surface 221B of the regulating part 220 is inclined with respect to the gate central axis LC.

[0090] The intermediate surface 221C of the regulating part 220 is located between the first side surface 221A and the second side surface 221B of the regulating part 220. The intermediate surface 221C of the regulating part 220 is connected to each side surface 221A, 221B of the regulating part 220. The intermediate surface 221C of the regulating part 220 is a curved surface. In the reference cross-section, the intermediate surface 221C of the regulating part 220 is shown by an arc. The center of the arc is defined outside the protrusion space S12.

[0091] The inner surface 221 of the restricting portion 220 includes a connecting surface 221D. The connecting surface 221D of the restricting portion 220 is located between the second side surface 221B of the restricting portion 220 and the inner surface 211 of the base portion 210. The connecting surface 221D of the restricting portion 220 is connected to the second side surface 221B of the restricting portion 220 and the inner surface 211 of the base portion 210. The connecting surface 221D of the restricting portion 220 is a curved surface. In a reference cross-section, the connecting surface 221D of the restricting portion 220 is shown by an arc. The center of the arc is defined in the protruding space S12.

[0092] The top portion 230 includes an inner surface 231. The inner surface 231 of the top portion 230 constitutes a part of the inner surface 201 of the protruding portion 200. The inner surface 231 of the top portion 230 does not overlap with the side surface of the base solid. The inner surface 231 of the top portion 230 is located radially inward of the gate insert 100 with respect to the side surface of the base solid.

[0093] The inner surface 231 of the top portion 230 is located between the first side surface 221A of the restricting portion 220 and the inner surface 121 of the gate land 120. The inner surface 231 of the top portion 230 is connected to the first side surface 221A of the restricting portion 220 and the inner surface 121 of the gate land 120. The inner surface 231 of the top portion 230 is a curved surface. In a reference cross-section, the inner surface 231 of the top portion 230 is shown by an arc. The center of the arc is defined in the protruding space S12.

[0094] Refer to FIG. 9. FIG. 9 shows a reference cross-section of the gate insert 100 when the position of the valve stem 24 is in the closed position. When the position of the valve stem 24 is in the closed position, a clearance (hereinafter referred to as "gate clearance 122") is formed between the outer peripheral surface 24B of the tip portion 24A of the valve stem 24 and the inner surface 121 of the gate land 120.

[0095] A resin material stays in the gate clearance 122. In the cooling process, the resin material staying in the gate clearance 122 is cooled, thereby forming an annular portion P240 of the protrusion P200 of the preform P10. The shape of the annular portion P240 corresponds to the shape of the gate clearance 122.

[0096] Cold slug C may be formed from the resin material staying in the gate clearance 122. The cold slug C adheres to the inner surface 121 of the gate land 120. In the molding process in which the cold slug C is formed, an annular portion P240 lacking a portion corresponding to the cold slug C is molded.

[0097] In the manufacturing process of the preform P10, the molding process is performed multiple times. For any two molding processes included in the multiple molding processes, the size of the gate clearance 122 may be different at the corresponding positions around the gate center axis LC. This is caused, for example, by the difference in the pressure distribution regarding the tip portion 24A of the valve stem 24. When the size of the gate clearance 122 is different, the shape of the annular portion P240 molded in each of the above two molding processes is also different.

[0098] Refer to FIG. 10. FIG. 10 shows a reference cross section of a gate insert (hereinafter referred to as "another gate insert") having a configuration different from that of the gate insert 100. For the following description based on another gate insert, the names and reference signs used in the description of the preform P10 and the injection mold 10 are applied mutatis mutandis.

[0099] Another gate insert does not include the restricting portion 220 and the top portion 230. In another gate insert, the entire inner surface 201 of the protrusion molding portion 200 is constituted by the inner surface 211 of the base portion 210. When the preform P10 is molded using another gate insert, as follows, molding defects regarding the main body P100 of the preform P10 due to the cold slug C may occur.

[0100] Examples of molding defects regarding the main body P100 of the preform P10 include a first type of molding defect and a second type of molding defect. In the following description, for two consecutive molding processes, the previously performed molding process is referred to as the "previous molding process", and the subsequently performed molding process is referred to as the "subsequent molding process".

[0101] The first type of molding defect occurs as follows, for example. In the previous molding process, a cold slug C is formed in the gate clearance 122. In the injection process of the subsequent molding process, the cold slug C flows from the gate clearance 122 into the molding space SM together with the resin material injected from the nozzle tip 21.

[0102] The cold slug C reaches, for example, the molding space SM corresponding to the bottom space S11, the molding space SM corresponding to the second internal space S20, or the molding space SM corresponding to the third internal space S30. The cold slug C stays in the resin material in a state of being separated from the inner surface 141 of the bottom molding part 140, the inner surface 51 of the cavity 50, or the inner surface 61 of the neck ring 60, and in a state of being separated from the first part 71A of the core 71.

[0103] In the cooling process of the subsequent molding process, the resin material containing the cold slug C is cooled. The cold slug C is included in the main body P100 of the molded preform P10. The cold slug C is included, for example, in the bottom part P110, the body part P120, or the opening part P130 of the main body P100 of the preform P10.

[0104] The second type of molding defect occurs as follows, for example. In the previous molding process, a cold slug C is formed in the gate clearance 122. In the injection process of the subsequent molding process, the cold slug C flows from the gate clearance 122 into the molding space SM together with the resin material injected from the nozzle tip 21. Examples of the behavior of the cold slug C in the molding space SM include, for example, the following first to third examples.

[0105] In the first example, the cold slug C moves along the inner surface 201 of the protrusion molding part 200 and the inner surface 141 of the bottom molding part 140 in the molding space SM. The cold slug C adheres to the inner surface 141 of the bottom molding part 140. In the second example, the cold slug C moves along the inner surface 131 of the forming part 130 and the inner surface 51 of the cavity 50 in the forming space SM. The cold slug C adheres to the inner surface 51 of the cavity 50. In the third example, the cold slug C moves along the inner surface 131 of the forming part 130, the inner surface 51 of the cavity 50, and the inner surface 61 of the necking 60 in the forming space SM. The cold slug C adheres to the inner surface 61 of the necking 60.

[0106] In the cooling process of the subsequent forming process, the resin material is cooled while the cold slug C adheres to the inner surface 141 of the bottom forming part 140, the inner surface 51 of the cavity 50, or the inner surface 61 of the necking 60. The cold slug C adheres to the outer periphery of the main body P100 of the formed preform P10.

[0107] In the mold opening process of the subsequent forming process, as the preform P10 is separated from the gate insert 100 and the cavity 50, the cold slug C is separated from the main body P100 of the preform P10. The cold slug C remains on the inner surface 141 of the bottom forming part 140, the inner surface 51 of the cavity 50, or the inner surface 61 of the necking 60. On the outer periphery of the main body P100 of the preform P10 taken out from the injection mold 10, a recess corresponding to the shape of the cold slug C is formed.

[0108] Referring to FIG. 9, when the gate insert 100 is used for forming the preform P10, for example, the occurrence of forming defects regarding the main body P100 of the preform P10 can be suppressed as follows.

[0109] In the injection process of the subsequent forming process, the cold slug C flows from the gate clearance 122 into the forming space SM together with the resin material ejected from the nozzle tip 21. The cold slug C gets caught on the restricting portion 220 of the protrusion forming portion 200. The movement of the cold slug C from the protrusion space S12 toward the bottom space S11 is obstructed by the restricting portion 220. The cold slug C stays in the forming space SM corresponding to the protrusion space S12.

[0110] In the cooling process of the subsequent forming process, the resin material is cooled while the cold slug C stays in the forming space SM corresponding to the protrusion space S12. The cold slug C is located between the outer periphery of the protrusion P200 of the preform P10 and the restricting portion 220. Examples of the state of the cold slug C in the mold opening process of the subsequent forming process include the following first example and second example.

[0111] In the first example, the following situation can be observed. In the mold opening process of the subsequent forming process, as the preform P10 is separated from the gate insert 100 and the cavity 50, the cold slug C is separated from the inner surface 201 of the protrusion forming portion 200. The cold slug C constitutes a part of the protrusion P200 of the preform P10. The cold slug C is included in the protrusion P200 of the preform P10 taken out from the injection mold 10.

[0112] In the second example, the following situation can be observed. In the mold opening process of the subsequent forming process, as the preform P10 is separated from the gate insert , the cold slug C is separated from the protrusion P200 of the preform P10. The cold slug C remains on the inner surface 201 of the protrusion forming portion 200.

[0113] In the forming process performed after the subsequent forming process, the cold slug C remaining on the inner surface 201 of the protrusion forming portion 200 may be separated from the inner surface 201 of the protrusion forming portion 200 in the mold opening process. In this case, similar to the first example, the cold slug C constitutes a part of the protrusion P200 of the preform P10.

[0114] As described above, it is possible to suppress the formation of the preform P10 in which the cold slug C is included in the main body P100, or the preform P10 in which the recess due to the cold slug C is provided in the main body P100.

[0115] (Second Embodiment) The second embodiment is configured on the premise of the first embodiment. In the second embodiment, an example of the dimensions related to the gate insert 100 is presented. The configuration regarding the inner surface 211 of the base portion 210 in the second embodiment is selected from, for example, the configuration of the first example or the configuration of the second example. The configuration of the first example is shown in FIG. 8.

[0116] The configuration of the first example is the same as the configuration illustrated in the first embodiment. The inner surface 211 of the base portion 210 is a curved surface. In the reference cross-section, the inner surface 211 of the base portion 210 is shown by an arc. The configuration of the second example is different from the configuration illustrated in the first embodiment. The inner surface 211 of the base portion 210 is a flat surface. In the reference cross-section, the inner surface 211 of the base portion 210 is shown by a line segment.

[0117] The radius of the arc showing the inner surface 211 of the base portion 210 is referred to as the "first radius". In the configuration of the first example, the first radius is larger than 0 mm. In the configuration of the second example, the first radius is 0 mm. The first radius is selected so as to be included in the reference range regarding the first radius. The reference range regarding the first radius will be exemplified.

[0118] The reference range of the first example is a range of the lower limit radius RA1 or more. The reference range of the second example is a range of the upper limit radius RA2 or less. The reference range of the third example is a range of the lower limit radius RA1 or more and the upper limit radius RA2 or less. The lower limit radius RA1 is selected from, for example, 0.5 mm, 0.8 mm, or 1.0 mm. The upper limit radius RA2 is selected from, for example, 5.0 mm, 4.0 mm, or 3.0 mm.

[0119] The configuration regarding the intermediate surface 221C of the regulation unit 220 in the second embodiment is selected from, for example, the configuration of the first example or the configuration of the second example. The configuration of the first example is shown in FIG. 8. The configuration of the first example is the same as the configuration illustrated in the first embodiment. The intermediate surface 221C of the regulation unit 220 is a curved surface. In the reference cross-section, the intermediate surface 221C of the regulation unit 220 is indicated by an arc.

[0120] The configuration of the second example is different from the configuration illustrated in the first embodiment. The intermediate surface 221C of the regulation unit 220 includes two planes. One plane is a plane connected to the first side surface 221A of the regulation unit 220. The other plane is a plane connected to the second side surface 221B of the regulation unit 220. In the reference cross-section, the intermediate surface 221C of the regulation unit 220 is indicated by two line segments that form an intersection point.

[0121] The radius of the arc indicating the intermediate surface 221C of the regulation unit 220 is referred to as the "second radius". In the configuration of the first example, the second radius is greater than 0 mm. In the configuration of the second example, the second radius is 0 mm. The second radius is selected so as to be included in the reference range regarding the second radius. An example of the reference range regarding the second radius will be given.

[0122] The reference range of the first example is a range of not less than the lower limit radius RB1. The reference range of the second example is a range of not more than the upper limit radius RB2. The reference range of the third example is a range of not less than the lower limit radius RB1 and not more than the upper limit radius RB2. The lower limit radius RB1 is selected from, for example, 0.0 mm, 0.2 mm, or 0.3 mm. The upper limit radius RB2 is selected from, for example, 2.0 mm, 1.5 mm, or 1.0 mm.

[0123] The configuration regarding the connection surface 221D of the regulation unit 220 in the second embodiment is selected from, for example, the configuration of the first example or the configuration of the second example. The configuration of the first example is shown in FIG. 8. The configuration of the first example is the same as the configuration illustrated in the first embodiment. The connection surface 221D of the regulation unit 220 is a curved surface. In the reference cross-section, the connection surface 221D of the regulation unit 220 is indicated by an arc.

[0124] The configuration of the second example is different from the configuration exemplified in the first embodiment. The connection surface 221D of the restricting portion 220 includes two planes. One plane is a plane connected to the inner surface 211 of the base portion 210. The other plane is a plane connected to the second side surface 221B of the restricting portion 220. In the reference cross-section, the connection surface 221D of the restricting portion 220 is indicated by two line segments that form an intersection point.

[0125] The radius of the arc indicating the connection surface 221D of the restricting portion 220 is referred to as the "third radius". In the configuration of the first example, the third radius is greater than 0 mm. In the configuration of the second example, the third radius is 0 mm. The third radius is selected so as to be included in the reference range regarding the third radius. An example of the reference range regarding the third radius will be given.

[0126] The reference range of the first example is a range of not less than the lower limit radius RC1. The reference range of the second example is a range of not more than the upper limit radius RC2. The reference range of the third example is a range of not less than the lower limit radius RC1 and not more than the upper limit radius RC2. The lower limit radius RC1 is selected, for example, from 0.0 mm, 0.2 mm, or 0.3 mm. The upper limit radius RC2 is selected, for example, from 1.5 mm, 1.0 mm, or 0.5 mm.

[0127] The configuration regarding the inner surface 231 of the top portion 230 in the second embodiment is selected, for example, from the configuration of the first example or the configuration of the second example. The configuration of the first example is shown in FIG. 8. The configuration of the first example is the same as the configuration exemplified in the first embodiment. The inner surface 231 of the top portion 230 is a curved surface. In the reference cross-section, the inner surface 231 of the top portion 230 is indicated by an arc.

[0128] The configuration of the second example is different from the configuration exemplified in the first embodiment. The inner surface 231 of the top portion 230 includes two planes. One plane is a plane connected to the first side surface 221A of the restricting portion 220. The other plane is a plane connected to the inner surface 121 of the gate land 120. In the reference cross-section, the inner surface 231 of the top portion 230 is indicated by two line segments that form an intersection point.

[0129] The radius of the arc showing the inner surface 231 of the top portion 230 is referred to as the "fourth radius". In the configuration of the first example, the fourth radius is greater than 0 mm. In the configuration of the second example, the fourth radius is 0 mm. The fourth radius is selected so as to be included in a reference range regarding the fourth radius. An example of the reference range regarding the fourth radius will be illustrated.

[0130] The reference range of the first example is a range of the lower limit radius RD1 or more. The reference range of the second example is a range of the upper limit radius RD2 or less. The reference range of the third example is a range of the lower limit radius RD1 or more and the upper limit radius RD2 or less. The lower limit radius RD1 is selected from, for example, 0.0 mm, 0.2 mm, or 0.3 mm. The upper limit radius RD2 is selected from, for example, 1.5 mm, 1.0 mm, or 0.5 mm.

[0131] Refer to FIG. 11. FIG. 11 shows an enlarged view of the restricting portion 220. A straight line parallel to the radial direction of the gate insert 100 in the reference cross section is referred to as the "reference line LL". The configuration regarding the first side surface 221A of the restricting portion 220 in the second embodiment is selected from, for example, the configuration of the first example or the configuration of the second example. The configuration of the first example is shown in FIG. 11.

[0132] The configuration of the first example is the same as the configuration illustrated in the first embodiment. The portion corresponding to the first side surface 221A of the restricting portion 220 has a taper. In the reference cross section, the first side surface 221A of the restricting portion 220 is inclined with respect to the reference line LL. The configuration of the second example is different from the configuration illustrated in the first embodiment. The portion corresponding to the first side surface 221A of the restricting portion 220 does not have a taper. In the reference cross section, the first side surface 221A of the restricting portion 220 is orthogonal to the reference line LL.

[0133] An angle showing the inclination of the first side surface 221A of the restricting portion 220 with respect to the radial direction of the gate insert 100 is referred to as the "first angle TA". In the reference cross section, the first angle TA is an angle formed by the first side surface 221A and the reference line LL. In the configuration of the first example, the first angle TA is greater than 0°. In the configuration of the second example, the first angle TA is 90°. The first angle TA is selected to be included in the reference range for the first angle TA. An example of the reference range for the first angle TA will be given.

[0134] The reference range of the first example is a range of not less than the lower limit angle TA1. The reference range of the second example is a range of not more than the upper limit angle TA2. The reference range of the third example is a range that is not less than the lower limit angle TA1 and not more than the upper limit angle TA2. The lower limit angle TA1 is selected, for example, from 30°, 40°, or 50°. The upper limit angle TA2 is selected, for example, from 90°, 80°, or 70°.

[0135] The configuration regarding the second side surface 221B of the restricting portion 220 in the second embodiment is selected, for example, from the configuration of the first example or the configuration of the second example. The configuration of the first example is shown in FIG. 11. The configuration of the first example is the same as the configuration illustrated in the first embodiment. The portion corresponding to the second side surface 221B of the restricting portion 220 has a taper. In the reference cross-section, the second side surface 221B of the restricting portion 220 is inclined with respect to the reference line LL.

[0136] The configuration of the second example is different from the configuration illustrated in the first embodiment. The portion corresponding to the second side surface 221B of the restricting portion 220 does not have a taper. In the reference cross-section, the second side surface 221B of the restricting portion 220 is parallel to the reference line LL.

[0137] The angle indicating the inclination of the second side surface 221B of the restricting portion 220 is referred to as the "second angle TB". In the reference cross-section, the second angle TB is the angle formed by the second side surface 221B and the reference line LL. In the configuration of the first example, the second angle TB is greater than 0°. In the configuration of the second example, the second angle TB is 0°. The second angle TB is selected to be included in the reference range for the second angle TB. An example of the reference range for the second angle TB will be given.

[0138] The reference range of the first example is a range of the lower limit angle TB1 or more. The reference range of the second example is a range of the upper limit angle TB2 or less. The reference range of the third example is a range of the lower limit angle TB1 or more and the upper limit angle TB2 or less. The lower limit angle TB1 is selected, for example, from 0.0°, 0.5°, or 1.0°. The upper limit angle TB2 is selected, for example, from 60°, 40°, or 20°.

[0139] (Third Embodiment) The third embodiment is configured on the premise of the first or second embodiment. In the third embodiment, an example of the dimensions related to the gate insert 100 is presented. Referring to FIG. 12, the dimensions of the gate insert 100 in the radial direction of the gate insert 100 are illustrated.

[0140] The center of the intermediate surface 221C of the regulating portion 220 is referred to as the "intermediate surface center". When the intermediate surface 221C of the regulating portion 220 is a curved surface, the intermediate surface center is the center on the circumference of the arc indicating the intermediate surface 221C of the regulating portion 220. When the intermediate surface 221C of the regulating portion 220 includes two planes, the intermediate surface center is the intersection of the two line segments indicating the intermediate surface 221C of the regulating portion 220.

[0141] The center of the connection surface 221D of the regulating portion 220 is referred to as the "connection surface center". When the connection surface 221D of the regulating portion 220 is a curved surface, the connection surface center is the center on the circumference of the arc indicating the connection surface 221D of the regulating portion 220. When the connection surface 221D of the regulating portion 220 includes two planes, the connection surface center is the intersection of the two line segments indicating the connection surface 221D of the regulating portion 220.

[0142] The distance between the gate center axis LC and the intermediate surface center in the radial direction of the gate insert 100 is referred to as the "first radial distance RY1". The distance between the intermediate surface center and the connection surface center in the radial direction of the gate insert 100 is referred to as the "second radial distance RY2". The combined distance of the first radial distance RY1 and the second radial distance RY2 is referred to as the "third radial distance RY3".

[0143] The ratio of the first radial distance RY1 to the third radial distance RY3 is referred to as the "radial ratio RR". The radial ratio RR is selected to be included in a reference range regarding the radial ratio RR. An example of the reference range regarding the radial ratio RR will be given.

[0144] The reference range of the first example is a range of not less than the lower limit ratio RR1. The reference range of the second example is a range of not more than the upper limit ratio RR2. The reference range of the third example is a range of not less than the lower limit ratio RR1 and not more than the upper limit ratio RR2. The lower limit ratio RR1 is selected, for example, from 5.0%, 6.0%, or 7.0%. The upper limit ratio RR2 is selected, for example, from 50%, 30%, or 15%.

[0145] Referring to FIG. 12, an example of the dimensions of the gate insert 100 in the axial direction of the gate insert 100 will be given. In the reference cross-section, the intersection point of the line segment LR3 indicating the top surface of the base solid of the protrusion space S12 and the gate central axis LC is referred to as the "first intersection point HA". In the reference cross-section, the intersection point of the reference line LL passing through the center of the intermediate surface and the gate central axis LC is referred to as the "second intersection point HB". In the reference cross-section, the intersection point of the curve LQ1 indicating the hemispherical surface of the base solid of the bottom space S11 and the gate central axis LC is referred to as the "third intersection point HC".

[0146] The distance between the first intersection point HA and the second intersection point HB in the axial direction is referred to as the "first axial distance HX1". The distance between the second intersection point HB and the third intersection point HC in the axial direction is referred to as the "second axial distance HX2". The combined distance of the first axial distance HX1 and the second axial distance HX2 is referred to as the "third axial distance HX3".

[0147] The ratio of the first axial distance HX1 to the third axial distance HX3 is referred to as the "axial ratio HR". The axial ratio HR is selected to be included in a reference range regarding the axial ratio HR. An example of the reference range regarding the axial ratio HR will be given.

[0148] The reference range of the first example is a range of the lower limit ratio HR1 or higher. The reference range of the second example is a range of the upper limit ratio HR2 or lower. The reference range of the third example is a range of the lower limit ratio HR1 or higher and the upper limit ratio HR2 or lower. The lower limit ratio HR1 is selected, for example, from 8.0%, 9.0%, or 10%. The upper limit ratio HR2 is selected, for example, from 50%, 40%, or 30%.

[0149] The third-axis direction distance HX3 is selected so as to be included in the reference range for the third-axis direction distance HX3. An example of the reference range for the third-axis direction distance HX3 will be illustrated. The reference range of the first example is a range of the lower limit distance HXA or higher. The reference range of the second example is a range of the upper limit distance HXB or lower. The reference range of the third example is a range of the lower limit distance HXA or higher and the upper limit distance HXB or lower. The lower limit distance HXA is selected, for example, from 0.5 mm, 1.0 mm, or 1.5 mm. The upper limit distance HXB is selected, for example, from 5.0 mm, 4.0 mm, or 3.0 mm.

[0150] (Fourth Embodiment) The fourth embodiment is configured on the premise of the first to third embodiments. In the fourth embodiment, an example of the dimensions related to the gate insert 100 is presented.

[0151] The reference range for the first radius is determined, for example, as follows. The lower limit radius RA1 is 0.5 mm. The upper limit radius RA2 is 5.0 mm. The first radius range is a range of 0.5 mm or higher and 5.0 mm or lower. The reference range for the second radius is determined, for example, as follows. The lower limit radius RB1 is 0.0 mm. The upper limit radius RB2 is 2.0 mm. The second radius range is a range of 0.0 mm or higher and 2.0 mm or lower.

[0152] The reference range for the third radius is determined, for example, as follows. The lower limit radius RC1 is 0.0 mm. The upper limit radius RC2 is 1.5 mm. The third radius range is a range of 0.0 mm or higher and 1.5 mm or lower. The reference range for the fourth radius is determined as follows, for example. The lower limit radius RD1 is 0.0 mm. The upper limit radius RD2 is 1.5 mm. The fourth radius range is in the range of 0.0 mm or more and 1.5 mm or less.

[0153] The reference range for the first angle TA is determined as follows, for example. The lower limit angle TA1 is 30°. The upper limit angle TA2 is 90°. The reference range for the second angle TB is determined as follows, for example. The lower limit angle TB1 is 0.0°. The upper limit angle TB2 is 60°.

[0154] The range for the radial ratio RR is determined as follows, for example. The lower limit ratio RR1 is 5.0%. The upper limit ratio RR2 is 50%. The reference range for the axial ratio HR is determined as follows, for example. The lower limit ratio HR1 is 8.0%. The upper limit ratio HR2 is 50%. The reference range for the third axial distance HX3 is determined as follows, for example. The lower limit distance HXA is 0.5 mm. The upper limit distance HXB is 5 mm.

[0155] (Fifth Embodiment) The fifth embodiment is configured on the premise of any one of the first to fourth embodiments. In the fifth embodiment, an example of the dimensions related to the gate clearance 122 is presented.

[0156] Referring to FIG. 9, regarding the state of the injection mold 10, a state where the central axis of the flow path 120A of the gate land 120 coincides with the central axis of the valve stem 24 is referred to as the "reference state of the injection mold 10". The size of the gate clearance 122 in the reference state of the injection mold 10 is referred to as the "clearance distance CL".

[0157] In the reference cross-section, the clearance distance CL is the length of the reference line LL connecting the inner surface 121 of the gate land 120 and the outer peripheral surface 24B of the tip 24A of the valve stem 24. The clearance distance CL is selected to be within the reference range for the clearance distance CL. An example of the reference range for the clearance distance CL will be illustrated.

[0158] The reference range of the first example is a range of not less than the lower limit distance CL1. The reference range of the second example is a range of not more than the upper limit distance CL2. The reference range of the third example is a range of not less than the lower limit distance CL1 and not more than the upper limit distance CL2. The lower limit distance CL1 is selected, for example, from 0.005 mm, 0.010 mm, or 0.015 mm. The upper limit distance CL2 is selected, for example, from 0.040 mm, 0.035 mm, or 0.030 mm.

[0159] (Sixth Embodiment) The sixth embodiment is configured on the premise of the fifth embodiment. In the sixth embodiment, an example of the dimensions related to the gate insert 100 and the valve stem 24 is presented.

[0160] In the first example, each dimension is selected as follows. The inner diameter of the flow path 120A of the gate land 120 is, for example, 3.42 mm. The outer diameter of the tip portion 24A of the valve stem 24 is, for example, 3.40 mm. The clearance distance CL is, for example, 0.010 mm. In the second example, each dimension is selected as follows. The inner diameter of the flow path RE is, for example, 3.44 mm. The outer diameter of the stem RF is, for example, 3.40 mm. The clearance distance CL is, for example, 0.020 mm.

[0161] (Seventh Embodiment) The seventh embodiment is configured on the premise of any one of the first to sixth embodiments. In the gate insert 100 of the seventh embodiment, the configuration of the protrusion forming portion 200 is different from that of the premise embodiment. The protrusion forming portion 200 can take, for example, the configuration of the following first example or second example.

[0162] In the first example, the basic solid corresponding to the protrusion space S12 of the protrusion forming portion 200 is a frustum of a sphere. The diameter of the basic solid becomes smaller as it progresses in the X1 direction. In the second example, the basic solid corresponding to the protruding space S12 is a columnar body. The shape of the columnar body is a frustum of a cone. The outer diameter of the basic solid decreases as it progresses in the X1 direction.

[0163] (Eighth Embodiment) The eighth embodiment is configured on the premise of any one of the first to seventh embodiments. In the gate insert 100 of the eighth embodiment, the configuration of the protruding portion forming portion 200 is different from that of the premise embodiment. The change in the configuration of the protruding portion forming portion 200 is reflected in the shape of the preform P10. The protruding portion forming portion 200 can take, for example, the configuration of the following first example or second example.

[0164] In the first example, the protruding portion forming portion 200 includes a base portion 210 and a restricting portion 220. The restricting portion 220 is provided in the middle portion of the base portion 210 with respect to the axial direction of the gate insert 100. The base portion 210 includes a portion located in the X1 direction with respect to the restricting portion 220 and a portion located in the X2 direction with respect to the restricting portion 220.

[0165] An example of the position of the restricting portion 220 with respect to the axial direction of the gate insert 100 will be illustrated. In the first example, the position of the center of the restricting portion 220 with respect to the axial direction of the gate insert 100 is the same as the position of the center of the base portion 210. In the second example, the restricting portion 220 is provided closer to the gate land 120 than the center of the base portion 210. In the third example, the restricting portion 220 is provided closer to the bottom forming portion 140 than the center of the base portion 210.

[0166] The inner surface 221 of the restricting portion 220 includes a second connecting surface. The second connecting surface is configured in accordance with the connecting surface 221D of the restricting portion 220 in the premise embodiment. The second connecting surface of the restricting portion 220 is located between the first side surface 221A of the restricting portion 220 and the inner surface 211 of the base portion 210. The second connecting surface of the restricting portion 220 is connected to the first side surface 221A of the restricting portion 220 and the inner surface 211 of the base portion 210. The second connecting surface of the restricting portion 220 is a curved surface. In the reference cross-section, the second connecting surface of the restricting portion 220 is indicated by an arc. The center of the arc is defined in the protruding space S12.

[0167] In the second example, the protrusion forming portion 200 includes a base portion 210, a restricting portion 220, and a bottom portion. The restricting portion 220 is located in the X2 direction with respect to the base portion 210. The restricting portion 220 is provided closer to the bottom forming portion 140 with respect to the axial direction of the gate insert 100. The inner surface 221 of the restricting portion 220 includes a second connection surface.

[0168] The bottom portion is configured according to the top portion 230. The bottom portion includes an inner surface. The inner surface of the bottom portion constitutes a part of the inner surface 201 of the protrusion forming portion 200. The inner surface of the bottom portion does not overlap with the side surface of the base solid. The inner surface of the bottom portion is located radially inward with respect to the side surface of the base solid. The inner surface of the bottom portion is located between the second side surface 221B of the restricting portion 220 and the inner surface 141 of the bottom forming portion 140. The inner surface of the bottom portion is connected to the second side surface 221B of the restricting portion 220 and the inner surface 141 of the bottom forming portion 140. The inner surface of the bottom portion is a curved surface. In a reference cross-section, the inner surface of the bottom portion is indicated by an arc. The center of the arc is defined in the protrusion space S12 or the bottom space S11.

[0169] (Ninth Embodiment) The ninth embodiment is configured on the premise of any one of the first to eighth embodiments. In the gate insert 100 of the ninth embodiment, the configuration of the protrusion forming portion 200 is different from that of the premise embodiment. The change in the configuration of the protrusion forming portion 200 is reflected in the shape of the preform P10.

[0170] The restricting portion 220 is configured to protrude with respect to the base solid. The restricting portion 220 is configured to be recessed radially outward of the gate insert 100 with respect to the base portion 210. The inner surface 221 of the restricting portion 220 is located radially outward with respect to the side surface of the base solid. The inner surface 221 of the restricting portion 220 is configured to be recessed radially outward with respect to the inner surface 211 of the base portion 210.

[0171] (Tenth Embodiment) The tenth embodiment is configured on the premise of any one of the first to ninth embodiments. In the gate insert 100 of the tenth embodiment, the configuration of the protrusion forming portion 200 is different from that of the premise embodiment. The change in the configuration of the protrusion forming portion 200 is reflected in the shape of the preform P10. The protrusion forming portion 200 includes a plurality of restricting portions 220. The plurality of restricting portions 220 are provided at intervals in the axial direction of the gate insert 100.

[0172] (Eleventh Embodiment) The eleventh embodiment is configured on the premise of any one of the first to tenth embodiments. In the gate insert 100 of the eleventh embodiment, the configuration of the protrusion forming portion 200 is different from that of the premise embodiment. The change in the configuration of the protrusion forming portion 200 is reflected in the shape of the preform P10. The protrusion forming portion 200 includes a plurality of restricting portions 220. The plurality of restricting portions 220 are provided at intervals around the gate central axis LC. The length of each restricting portion 220 in the circumferential direction is shorter than the circumference.

[0173] (Twelfth Embodiment) The twelfth embodiment is configured on the premise of any one of the first to twelfth embodiments. The protrusion P200 of the preform P10 in the twelfth embodiment is a long gate. In the gate insert 100 of the twelfth embodiment, the configuration of the protrusion forming portion 200 is different from that of the gate insert 100 of the premise embodiment.

[0174] The protrusion forming portion 200 of the gate insert 100 in the twelfth embodiment is configured according to the protrusion forming portion 200 of the premise embodiment so as to be able to form the protrusion P200 of the long gate. The manufacturing method of the preform P10 includes a molding step and a cutting step. The cutting step is performed after the molding step. In the cutting step, the protrusion P200 of the preform P10 is cut. The cutting site of the protrusion P200 is, for example, the middle part of the base portion P210 of the protrusion P200.

[0175] When the protrusion P200 is cut, the portion located in the X1 direction with respect to the cut surface of the protrusion P200 is separated from the preform P10. The portion located in the X2 direction with respect to the cut surface of the protrusion P200 remains on the preform P10.

[0176] (Embodiment 13) Embodiment 13 is configured on the premise of any one of Embodiments 1 to 13. The preform P10 of Embodiment 13 has a layer structure. The preform P10 includes a plurality of components laminated in the radial direction of the preform P10. In one example, the preform P10 includes an inner layer and an outer layer.

[0177] (Effect) The effects obtained by the gate insert 100, the fixing unit 40, and the manufacturing method of the preform P10 are exemplified.

[0178] The tendency of forming defects in the main body P100 of the preform P10 and the life of the gate insert 100 are related to, for example, the clearance distance CL. The larger the clearance distance CL, the less likely the tip 24A of the valve stem 24 is to contact the inner surface 121 of the gate land 120. The inner surface 121 of the gate land 120 is less likely to wear. The life of the gate insert 100 becomes longer. The replacement frequency of the gate insert 100 decreases. The running cost related to the injection mold 10 is reduced.

[0179] The smaller the clearance distance CL, the less the amount of resin material staying in the gate clearance 122. It becomes less likely for the cold slug C to be formed in the gate clearance 122.

[0180] In an example of the gate insert 100, the first radius is equal to or greater than the lower limit radius RA1. According to the above configuration, for example, the following effects can be obtained. The protrusion P200 of the preform P10 is more likely to be separated from the protrusion forming portion 200.

[0181] In an example of the gate insert 100, the first radius is equal to or less than the upper limit radius RA2. According to the above configuration, for example, the following effects can be obtained. The effect of preventing the movement of the cold slug C is easily obtained. The protrusion P200 of the preform P10 is easily separated from the protrusion forming portion 200.

[0182] In an example of the gate insert 100, the second radius is equal to or greater than the lower limit radius RB1. According to the above configuration, for example, the following effects can be obtained. The protrusion P200 of the preform P10 is easily separated from the protrusion forming portion 200. Sink marks are less likely to be formed on the protrusion P200 of the preform P10.

[0183] In an example of the gate insert 100, the second radius is equal to or less than the upper limit radius RB2. According to the above configuration, for example, the following effects can be obtained. The effect of preventing the movement of the cold slug C is easily obtained. The protrusion P200 of the preform P10 is easily separated from the protrusion forming portion 200.

[0184] In an example of the gate insert 100, the third radius is equal to or greater than the lower limit radius RC1. According to the above configuration, for example, the following effects can be obtained. The protrusion P200 of the preform P10 is easily separated from the protrusion forming portion 200.

[0185] In an example of the gate insert 100, the third radius is equal to or less than the upper limit radius RC2. According to the above configuration, for example, the following effects can be obtained. The effect of preventing the movement of the cold slug C is easily obtained. The protrusion P200 of the preform P10 is easily separated from the protrusion forming portion 200.

[0186] In an example of the gate insert 100, the fourth radius is equal to or greater than the lower limit radius RD1. According to the above configuration, for example, the following effects can be obtained. The protrusion P200 of the preform P10 is easily separated from the protrusion forming portion 200.

[0187] In an example of the gate insert 100, the fourth radius is equal to or less than the upper limit radius RD2. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C. The protrusion P200 of the preform P10 is more likely to separate from the protrusion forming portion 200.

[0188] In an example of the gate insert 100, the first angle TA is equal to or greater than the lower limit angle TA1. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C.

[0189] In an example of the gate insert 100, the first angle TA is equal to or less than the upper limit angle TA2. According to the above configuration, for example, the following effects can be obtained. The protrusion P200 of the preform P10 is more likely to separate from the protrusion forming portion 200.

[0190] In an example of the gate insert 100, the second angle TB is equal to or greater than the lower limit angle TB1. According to the above configuration, for example, the following effects can be obtained. The protrusion P200 of the preform P10 is more likely to separate from the protrusion forming portion 200.

[0191] In an example of the gate insert 100, the second angle TB is equal to or less than the upper limit angle TB2. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C. The protrusion P200 of the preform P10 is more likely to separate from the protrusion forming portion 200.

[0192] In an example of the gate insert 100, the radial ratio RR is equal to or greater than the lower limit ratio RR1. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C.

[0193] In an example of the gate insert 100, the radial ratio RR is equal to or less than the upper limit ratio RR2. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C.

[0194] In an example of the gate insert 100, the axial ratio HR is equal to or greater than the lower limit ratio HR1. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C.

[0195] In an example of the gate insert 100, the axial ratio HR is equal to or less than the upper limit ratio HR2. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C.

[0196] In an example of the gate insert 100, the third axial distance HX3 is equal to or greater than the lower limit distance HXA. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C. Whitening in the main body P100 of the preform P10 is less likely to occur. The quality regarding the appearance of the preform P10 is less likely to deteriorate.

[0197] In an example of the gate insert 100, the third axial distance HX3 is equal to or less than the upper limit distance HXB. According to the above configuration, for example, the following effects can be obtained. It becomes easier to obtain the effect of preventing the movement of the cold slug C. The protrusion P200 of the preform P10 is more likely to separate from the protrusion forming portion 200.

[0198] In an example of the gate insert 100, the clearance distance CL is equal to or greater than the lower limit distance CL1. According to the above configuration, the inner surface 121 of the gate land 120 and the outer peripheral surface 24B of the tip portion 24A of the valve stem 24 are less likely to wear.

[0199] In an example of the gate insert 100, the clearance distance CL is equal to or less than the upper limit distance CL2. According to the above configuration, for example, the following effects can be obtained. It becomes difficult for the cold slug C to be formed at the gate clearance 122. It becomes difficult for a state where the cold slug C stays in the gate clearance 122 for a long time to occur. It becomes difficult for burrs to be formed on the protrusion P200 of the preform P10.

[0200] Note that the possible forms of the gate insert, fixing unit, and preform manufacturing method according to the present invention are not limited to the descriptions in the above embodiments. The gate insert, fixing unit, and preform manufacturing method according to the present invention can take forms different from those exemplified in the embodiments. Examples thereof include forms in which a part of the configuration of each embodiment is replaced, changed, or omitted, or forms in which a new configuration is added to each embodiment.

Explanation of Reference Numerals

[0201] 40: Fixing unit 100: Gate insert 120: Gate land 200: Protrusion forming part 210: Base part 220: Regulation part 221A: First side surface 221B: Second side surface 221C: Intermediate surface P10: Preform P110: Bottom part P200: Protrusion

Claims

1. A gate insert for a fixed unit that molds a preform, comprising a protrusion forming portion corresponding to a protrusion at the bottom of the preform, wherein the protrusion forming portion includes a restricting portion configured to prevent the movement of cold slags, and the restricting portion is configured to protrude with respect to the base portion of the protrusion forming portion gate insert.

2. The gate insert according to claim 1, wherein the restricting portion is configured to make one full turn around the central axis of the gate insert. The gate insert according to claim 1.

3. The gate insert according to claim 1 or 2, wherein the restricting portion is provided closer to the gate land in a direction parallel to the central axis of the gate insert. The gate insert according to claim 1 or 2.

4. The gate insert according to any one of claims 1 to 3, wherein the restricting portion includes a first side surface, a second side surface, and an intermediate surface, the first side surface is located between the intermediate surface and the gate land, and the second side surface is located between the intermediate surface and the base portion. The gate insert according to any one of claims 1 to 3.

5. The gate insert according to claim 4, wherein the intermediate surface is a curved surface, and the radius of the arc representing the intermediate surface is included in the range of 2 mm or less. The gate insert according to claim 4.

6. The gate insert according to claim 4 or 5, wherein the angle indicating the inclination of the first side surface with respect to the radial direction of the gate insert is included in the range of 30° or more. The gate insert according to claim 4 or 5.

7. The gate insert according to any one of claims 4 to 6, wherein the angle indicating the inclination of the first side surface with respect to the radial direction of the gate insert is included in the range of 90° or less. The gate insert according to any one of claims 4 to 6.

8. A fixed unit comprising the gate insert according to any one of claims 1 to 7. fixed unit.

9. A method for manufacturing a preform, comprising a molding step of molding a preform using the fixed unit according to claim 8. preform manufacturing method.

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