Screw head, injection device, and injection stretch blow molding machine using the same

Abstract

To provide a screw head, an injection device, and an injection stretch blow molding machine using the same, which are capable of improving a stirring performance near an injection position.SOLUTION: There is provided a screw head, comprising: a substantially conical-shaped head; a neck portion integrally formed on one side of the head in an axial direction; and a connecting portion integrally formed on one side of the neck portion in the axial direction. The head has a plurality of stirring blades that protrude radially outward from an axis center of the head and are spaced apart in a circumferential direction, the stirring blades have side wall surfaces that extend along the radial direction and a top surface that extends along the circumferential direction, and an intersection part of the side wall surfaces and the top surface forms an acute angle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a screw head used in an injection unit, an injection unit, and an injection stretch blow molding machine using the same. [Background technology]

[0002] Conventionally, injection stretch blow molding machines that use the hot parison method to mold preforms into hollow bodies made of synthetic resin, such as PET bottles, have been used as machines for manufacturing such hollow bodies. These machines are arranged in a circular pattern on a flat surface at equal intervals, in order: an injection molding section that molds preforms using an injection mold; a blow molding section that places the preform in a blow mold and stretches and blows (by blowing compressed air) it into a hollow body; and an ejection section that sends the molded hollow body out of the machine. In such injection stretch blow molding machines, an inline screw injection unit is used as the injection unit for molding the preforms in the injection molding section.

[0003] Incidentally, in recent years, there have been attempts with injection stretch blow molding machines to increase the production efficiency of hollow bodies by early demolding the preform in the injection molding section, thereby shortening the time required for the injection molding process, blow molding process, and removal process.

[0004] For example, Patent Document 1 discloses an invention in which, in an inline screw type injection device, the screw 2 is rotated throughout the primary injection stroke and the pressure holding stroke, thereby shortening the molding cycle and increasing the injection amount as much as possible.

[0005] Patent Document 2 also discloses an invention in which, in order to shorten the molding cycle, the screw is rotated simultaneously with the start of injection, and plasticization and kneading to produce the next shot of molten resin is carried out from the start of injection, and further, the plasticized and kneaded molten resin to be injected in the next injection cycle is not sent to the space in front of the screw during filling.

[0006] As a result, the invention disclosed in Patent Document 2 reliably melts the solid resin material (chips) before sending it out into the space in front of the screw, and prevents poorly melted molten resin from mixing with the shot being filled.

[0007] In an in-line screw injection device, a screw head is attached to the tip of the screw. Prior art related to the screw head is disclosed in Patent Document 3.

[0008] Patent document 3 discloses an invention of a screw head in which, in order to eliminate uneven temperature of the molten resin, a stirring section 3B is formed at the tip of the screw head 3, which is made by carving a plurality of stirring grooves 3d into the cylindrical outer surface, extending along its axis and dividing the outer periphery. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-207792 [Patent Document 2] Patent Publication No. 2021-181183 [Patent Document 3] Japanese Patent Application Publication No. 57-197135 Summary of the Invention [Problem to be solved by the invention]

[0010] An advantage of the rotational injection molding disclosed in Patent Documents 1 and 2 is that the screw continues to rotate during injection, so the metering time can be shortened compared to conventional injection molding.

[0011] In addition, in rotational injection molding, the time required for the molding cycle is the same as the metering time, so the screw rotation speed is slower than in conventional molding and the rotation time is longer, as the metering completion time must be synchronized with the next injection. This improves the plasticization and kneading of the molten resin, so the temperature of the injected molten resin can be lower than in conventional injection molding.

[0012] Focusing on the screw, the screw disclosed in Patent Document 3 has a stirring section 3B formed at the tip of the screw head 3, which extends along the axis of the cylindrical outer surface and has multiple stirring grooves 3d carved into it to divide the outer periphery, in order to eliminate temperature unevenness in the molten resin.

[0013] However, the screw disclosed in Patent Document 3 is simply provided with a plurality of stirring grooves 3d, and although it may be possible to improve the kneading, there is still ample room for improvement.

[0014] An object of the present invention is to provide a screw head, an injection unit, and an injection stretch blow molding machine using the same that can improve the stirring performance in the vicinity of the injection position. [Means for solving the problem]

[0015] The present invention provides a nozzle comprising a substantially conical head, a neck portion integrally formed on one side of the head in the axial direction, and a connecting portion integrally formed on one side of the neck portion in the axial direction, The head The head has a plurality of stirring blades that protrude radially outward from the axis of the head and are spaced apart in the circumferential direction, The stirring blade has a side wall surface extending along the radial direction and a top surface along the circumferential direction, The screw head is characterized in that the intersection between the side wall surface and the top surface forms an acute angle.

[0016] In the present invention, a recessed groove is formed in the top surface along the circumferential direction.

[0017] The present invention also provides a molten resin injection device comprising the above-mentioned screw head.

[0018] The present invention also provides an injection stretch blow molding machine having at least an injection molding section for molding a preform, a blow molding section for stretching and blowing the molded preform to form a hollow body, and a take-out section for sending the hollow body formed in the blow molding section out of the molding machine, the injection molding unit has an injection mold and an injection device that injects molten resin into the injection mold, The injection device A substantially conical head; a neck portion integrally formed on one side of the head in the axial direction; a connecting portion integrally formed on one side of the neck portion in the axial direction, The head The head has a plurality of stirring blades that protrude radially outward from the axis of the head and are spaced apart in the circumferential direction, The stirring blade has a side wall surface extending along the radial direction and a top surface along the circumferential direction, The injection stretch blow molding machine is characterized by having a screw head in which the intersection between the side wall surface and the top surface is at an acute angle. [Effects of the Invention]

[0019] According to the present invention, the screw head comprises a substantially conical head, a neck portion integrally formed on one side of the axial direction of the head, and a connecting portion integrally formed on one side of the axial direction of the neck portion, and has a plurality of stirring blades that protrude radially outward from the axis of the head and are formed at intervals in the circumferential direction, each stirring blade having a side wall surface extending along the radial direction and a top surface along the circumferential direction, and the intersection of the side wall surface and the top surface is formed at an acute angle.

[0020] By adopting this configuration, torque can be applied to the molten resin present between adjacent stirring blades, which generates a strong swirling flow in the molten resin near the injection position, thereby improving the stirring performance near the injection position.

[0021] Furthermore, according to the present invention, the top surface is formed with grooves extending in the circumferential direction, which generates a powerful and complex swirling flow in the molten resin near the injection position, thereby further improving the mixing performance near the injection position.

[0022] Furthermore, according to the present invention, since the injection device is provided with the screw head described above, it is possible to realize an injection device with improved stirring performance in the vicinity of the injection position.

[0023] Furthermore, according to the present invention, the injection stretch blow molding machine is provided with an injection device, and the injection device is provided with the above-mentioned screw head, so that an injection stretch blow molding machine with improved stirring performance in the vicinity of the injection position can be realized. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic plan view of an injection stretch blow molding machine. [Figure 2] FIG. 2 is an explanatory diagram schematically illustrating an injection device. [Figure 3] FIG. 10 is a view showing the vicinity of the tip of the screw. [Figure 4] FIG. 2 is a view showing the screw as viewed from the tip. [Figure 5] 5 is a cross-sectional view taken along the line AA in FIG. 4. [Figure 6] 5 is a cross-sectional view of FIG. 4 taken along line B-B. [Figure 7] FIG. 2 is an explanatory view showing the vicinity of the screw head 14 in a filled state. [Figure 8] FIG. 10 is an explanatory view showing a screw head 14A according to a second embodiment of the present invention. [Figure 9]FIG. 2 is an explanatory diagram showing a cross section of a screw head 14A. [Figure 10] FIG. 10 is an explanatory view showing the vicinity of a screw head 14A in a filled state. [Figure 11] FIG. 10 is an explanatory view showing a screw head 14B according to a third embodiment of the present invention. [Figure 12] FIG. 14 is a view of the screw head 14B seen from the tip side. [Figure 13] FIG. 10 is an explanatory diagram showing a cross section of a screw head 14B. DETAILED DESCRIPTION OF THE INVENTION

[0025] (Injection stretch blow molding machine) 1 is a schematic plan view of an example of an injection stretch blow molding machine according to an embodiment of the present invention. Injection stretch blow molding machine 1 has injection molding section 2, blow molding section 3, and removal section 4 arranged in this order at an angle of 120° on a plane, forming a circle.

[0026] The injection molding section 2 injects molten resin into an injection mold to mold a high-temperature preform. In particular, the injection stretch blow molding machine 1 of this embodiment is configured so that the preform can be quickly released from the mold while still being capable of being stretch-blowed in the blow molding section 3.

[0027] The molded preform is held by a lip mold incorporated as part of the injection mold and then released from the mold. The released preform is transferred to the blow molding section 3 and placed in the blow molding mold. The blow molding section 3 stretches the preform held by the lip mold and blows it with high-pressure air or the like to form a hollow body.

[0028] The blow-molded hollow body is transferred to the removal section 4 while being held in the lip mold. The removal section 4 is the section that sends the hollow body formed in the blow molding section 3 out of the molding machine. The injection stretch blow molding machine 1 moves the lip mold from the blow molding section 3 to the removal section 4, opens the lip mold to release the constraint on the hollow body, and removes it from the lip mold.

[0029] The hollow body released from the lip mold is sent out of the molding machine as described above. Then, the lip mold that released the hollow body moves back to the injection molding section 2 and is incorporated as part of the injection mold for the preform.

[0030] As described above, the injection stretch blow molding machine 1 transfers the preform molded in the injection molding section 2 to the blow molding section 3 using a lip mold, and transfers the hollow body blown in the blow molding section 3 to the removal section 4 using the lip mold, where the lip mold releases the hollow body.

[0031] (molding cycle) The injection stretch blow molding machine 1 continuously carries out an injection molding process in which the above-mentioned preform is injection molded, a blow molding process in which the preform molded in the injection molding process is blow molded into a hollow body, and an ejection process in which the hollow body molded in the blow molding process is sent out of the molding machine at an ejection section.

[0032] In the injection stretch blow molding machine 1, lip molds are provided in three locations so that the lip molds can simultaneously correspond to the three positions of the injection molding section 2, the blow molding section 3, and the take-out section 4.

[0033] The three lip molds are attached to a rotating plate, which is rotated 120 degrees in one direction and stopped, then lowered when stopped, raised after the injection cooling is completed, and then rotated 120 degrees in one direction again, and the same operation is repeated thereafter, so that the corresponding positions of the lip molds advance in order.

[0034] In the injection stretch blow molding machine 1, three lip molds simultaneously change their corresponding positions and move in sequence, and the molding cycle for a hollow body and the next molding cycle proceed with a one-step delay.

[0035] (injection device) 2 is an explanatory diagram schematically illustrating the injection device 6. The injection device 6 is an in-line screw type injection device in which a screw 9 is arranged inside a cylinder 8 of a barrel (heating cylinder) 7 so that the screw 9 can rotate and move forward and backward.

[0036] The injection device 6 supplies chip-like resin material from a feed hopper 10 to a supply portion of the screw 9, and the movement of the screw 9 moves the supplied resin material from a compression portion to a metering portion.

[0037] Shear heat is generated by the movement from the compression section to the metering section, and the resin material is plasticized and kneaded by the heat from the heater 11 and the stirring caused by the rotation of the screw, producing a molten resin.

[0038] The produced molten resin is sent forward of the screw 9, and the molten resin positioned in front of the screw 9 is injected into the injection molding die 5. A heater 11 is arranged on the outer periphery of the barrel 7 to promote plasticization of the resin material.

[0039] In the injection molding process, the injection device 6 performs the following functions: filling the injection mold 5 by sending molten resin; maintaining pressure on the molten resin sent to the injection mold 5 to prevent backflow of the molten resin; and metering the molten resin by sending it forward of the screw 9 so that a predetermined required amount of molten resin is injected into the injection mold 5.

[0040] The injection device 6 continuously repeats filling, pressure holding, and metering in a series, which is called an injection cycle. One injection cycle is injection (filling + pressure holding) + metering.

[0041] (Injection molding process - injection) In the injection molding process, when the injection unit 6 starts filling, the screw 9 is at the injection start position. The injection unit 6 rotates and moves the screw 9 forward from the injection start position. As the rotating screw 9 moves forward, the required amount of molten resin is injected into the injection mold 5.

[0042] Filling is performed by rotating the screw 9 with the drive unit and applying hydraulic pressure to the screw 9 in the forward direction (towards the injection mold 5). When it is determined that the screw 9 has reached a predetermined holding pressure switching position, injection ends by switching the pressure applied to the screw 9 to back pressure for holding.

[0043] During filling, when hydraulic pressure is applied to the screw 9 to move it forward, the resin pressure (injection pressure) in front of the screw 9 increases, causing the ring valve (a ring-shaped flow path opening and closing valve located at the tip of the screw) to close. Therefore, even when the production of molten resin begins as the screw 9 rotates, the molten resin does not flow from the metering section to the front of the screw 9. In other words, during filling, the molten resin that is plasticized and kneaded to be injected in the next injection cycle is not sent to the space in front of the screw 9.

[0044] As described above, in the injection unit 6, the screw 9 has been rotating since the start of injection (filling). The production of molten resin in the next molding cycle begins with the rotation of the screw 9. That is, in the injection unit 6, the start of injection and the start of production of the next shot of molten resin occur simultaneously.

[0045] (Injection molding process - holding pressure) After the injection unit 6 has finished filling, it continues to rotate the screw 9 from the time of the filling operation to maintain pressure.

[0046] In the injection unit 6, during pressure holding, a back pressure set for pressure holding is applied to the screw 9. At this time, the screw 9 continues to rotate from the time of filling, and continues to produce the molten resin for the next shot.

[0047] (Injection molding process - measurement) After completing the pressure dwell, the injection unit 6 continues the rotation of the screw 9 during pressure dwell and moves backward while rotating the screw 9 to perform metering. The metering operation is set so that it fits within the dry cycle time of mold opening, rotation, and mold closing in the injection molding section 2.

[0048] During metering, the injection unit 6 rotates the screw 9 while retracting it under back pressure. During metering, the rotation speed of the screw 9 is conventionally about 120 RPM, but in this embodiment it is set to a lower rotation speed than conventional speeds, for example, 70 to 80 RPM. During metering, the resin material is plasticized and kneaded, and a predetermined amount of molten resin is sent forward of the screw 9. When the screw 9 retracts and reaches the injection start position, its rotation is stopped, which stops the retraction of the screw 9 and ends metering.

[0049] When the screw 9 reaches the injection start position (measurement completion position), the injection unit 6 immediately starts the injection molding process without waiting time.

[0050] In this embodiment, when the screw 9 retreats to the injection start position, the rotation of the screw 9 stops, but the rotation of the screw 9 may continue.

[0051] In the injection unit 6 of this embodiment, plasticization kneading to produce the next shot of molten resin begins from the start of injection, so production of the next shot of molten resin can begin earlier than in conventional injection units that rotate the screw after completion of dwelling pressure. Therefore, production of the next shot of molten resin can be completed earlier than in conventional injection units, and the molding cycle can be shortened.

[0052] In addition, since the time required for metering is the time required for the molding cycle, the screw rotation speed during metering is lowered and the rotation time is longer. This improves the plasticization and kneading of the molten resin, allowing the temperature of the injected molten resin to be lower than in conventional injection molding.

[0053] In the injection device 6 of the embodiment, the screw 9 rotates continuously during filling, pressure holding, and metering, but the number of screw rotations per unit time does not need to be the same for filling, pressure holding, and metering. The number of screw rotations per unit time is variable for each of filling, pressure holding, and metering, and can be set appropriately for each of filling, pressure holding, and metering.

[0054] Incidentally, the above-mentioned feature of being able to vary the number of screw revolutions per unit time for each of filling, pressure holding, and metering naturally also includes changing the number of screw revolutions per unit time for each of filling, pressure holding, and metering.

[0055] (screw) Fig. 3 is a view showing the vicinity of the tip of the screw 9. Fig. 4 is a view showing the screw 9 as seen from the tip. Fig. 5 is a cross-sectional view taken along line AA in Fig. 4, and Fig. 6 is a cross-sectional view taken along line BB in Fig. 4.

[0056] The screw 9 is composed of a screw body 12 having a spiral groove formed on the outer surface of the cylindrical body, a seat ring 13 provided at one end of the screw body 12, a screw head 14 attached to one end of the screw body 12, and a ring valve 15 provided at a neck portion 21 of the screw head 14, which will be described later.

[0057] The screw body 12 has a supply section, a compression section, and a metering section (not shown), and transports the molten resin supplied from the feed hopper 10 toward the screw head 14. The supply section is a region where the molten resin is heated while being transported. The compression section is a region where the molten resin, which has also been preheated in the supply section, is pressurized and compressed, and mechanical energy is supplied to promote melting. The metering section is a region where the molten resin transported from the compression section is homogenized and rectified, and generates the pressure necessary for the molten resin to pass through the ring valve 15. This structure of the screw body 12 is no different from that of a conventional full-flighted screw.

[0058] (Screw head) The screw head 14 has a generally conical head 20, a neck portion 21 integrally formed on one side of the axial direction, which is the direction in which the axis L of the head 20 extends, and a connecting portion 22 integrally formed on one side of the axial direction of the neck portion 21.

[0059] The head 20 has a plurality of (four in this embodiment) stirring blades 30 that protrude radially outward from the axis of the head 20 and are spaced apart in the circumferential direction. Between adjacent stirring blades 30, concave grooves 31 are formed, through which the molten resin passes.

[0060] The stirring blade 30 has two side wall surfaces 40 extending radially, a top surface 41 that follows the circumferential direction of the head 20, an inclined surface 42 that connects to one end of the top surface 41 and slopes toward the tip of the screw head 14, and a back surface 43 that connects to the other end of the top surface 41 and extends radially.

[0061] The angle formed by the intersection 44 between the side wall surface 40 and the top surface 41 is set to an acute angle, preferably set to 80 to 90 degrees. As shown in FIG.

[0062] The neck portion 21 is formed in a substantially cylindrical shape. The ring valve 15 is attached to the neck portion 21 so that it can move axially. When the ring valve 15 is in the open position (tip end side), the neck portion 21 allows the molten resin to move toward the injection port through a gap between the neck portion 21 and the ring valve 15. When the ring valve 15 is in the closed position (rear end side), there is no gap between the neck portion 21 and the ring valve 15, and the molten resin does not move toward the injection port.

[0063] The connecting portion 22 is a portion that is connected to the screw body 12. The connecting portion 22 is formed in a substantially cylindrical shape, and has a male thread formed on its surface. An attachment portion for attaching the screw head 14 is provided at the tip of the screw body 12. The connecting portion 22 is connected to the screw body 12 by threading into a female thread formed on the attachment portion formed on the screw body 12.

[0064] 7 is an explanatory diagram showing the vicinity of the screw head 14 in the filling state. As described above, during filling, the injection device 6 applies hydraulic pressure to the screw 9 to move the screw 9 forward. At this time, the resin pressure (injection pressure) in front of the screw 9 increases, causing the ring valve 15 (a ring-shaped flow path opening / closing valve located at the tip of the screw) to close. Therefore, even when the generation of molten resin begins as the screw 9 rotates, the molten resin does not flow from the metering section to the front of the screw 9 (toward the injection port).

[0065] In this state, the screw 9 continues to rotate, so the molten resin to be injected (the molten resin located closer to the tip than the ring valve 15) is forced out to the injection port while forming a swirling flow. That is, the molten resin being injected is forced out to the injection port while being plasticized and kneaded, and then injected into the injection mold 5.

[0066] As shown in Figure 7, the screw head 14 has an agitating blade 30, which has a side wall surface 40 and a top surface 41, with the intersection 44 formed at an acute angle. As a result, the molten resin present in the concave groove 31 formed between adjacent agitating blades 30 receives torque in the rotational direction from the side wall surface 40 due to the rotation of the screw 9. The screw 9 moves forward toward the injection port while rotating, thereby generating a swirling flow in the molten resin.

[0067] By forming the intersecting portion 44 at an acute angle, torque can be applied to almost all of the molten resin inside the groove 31, generating a powerful swirling flow. This improves the plasticization and kneading of the molten resin, suppressing temperature unevenness and allowing the temperature of the injected molten resin to be lower than in conventional injection molding.

[0068] In this way, by using the screw head 14 of this embodiment, it is possible to improve the plasticization and kneading of the molten resin, suppress temperature variations, and lower the temperature of the injected molten resin than in conventional injection molding. Therefore, it is possible to reduce the waiting time of the preform in the blow molding mold, which is required in conventional blow molding processes to even out temperature variations in the preform, and this shortens the molding cycle.

[0069] In the prior art, when polypropylene was used as the molding material, it was necessary to provide a long waiting time for the preform in the blow molding die to eliminate temperature unevenness. However, by using the screw head 14 of this embodiment, the molten resin can be sufficiently mixed to provide a molded preform with reduced temperature unevenness, so the waiting time for the preform in the blow molding die can be reduced or eliminated.

[0070] Furthermore, for example, when the molding material contains granular pellets containing a filler, the screw head 14 of this embodiment can be used to sufficiently knead the molten resin during filling, thereby providing a preform molded from molten resin without uneven stirring, thereby enabling the production of desired molded products with a high yield.

[0071] Therefore, according to the present invention, it is possible to realize a screw head, an injection device, and an injection stretch blow molding machine using the same that can improve the stirring performance in the vicinity of the injection position.

[0072] Next, another embodiment of the present invention will be described. Fig. 8 is an explanatory diagram showing a screw head 14A according to a second embodiment of the present invention, and Fig. 9 is an explanatory diagram showing a cross section of the screw head 14A. Fig. 10 is an explanatory diagram showing the vicinity of the screw head 14A in a filled state. To avoid duplication of explanation, the same parts as in the above-described embodiment are designated by the same reference numerals, and explanations thereof will be omitted.

[0073] The screw head 14A has an agitating blade 30A. The agitating blade 30A has a top surface 41A. A groove 45 extending in the circumferential direction and having a generally V-shaped cross section is formed in the top surface 41A. The groove 45 is a groove that is recessed radially inward of the screw head 14, and the cross-sectional shape is not limited to a V-shape. Because the groove 45 is formed in the top surface 41A in this way, the agitating blade 30A has a front blade portion 50 located closer to the tip end than the groove 45, and a rear blade portion 51 located closer to the rear end than the groove 45.

[0074] When the screw head 14A is rotated, as shown in Figure 10, an annular gap having the cross-sectional shape of the groove 45 is formed between the molten resin stirred by the front wing portion 50 and the molten resin stirred by the rear wing portion 51, and the torque applied to the molten resin located in the annular gap is different from the torque applied to the molten resin located between each front wing portion 50 and between each rear wing portion 51.

[0075] Therefore, the molten resin stirred by the stirring blade 30A is subjected to a torque that is more dispersed than that of the stirring blade 30, and a complex swirling flow is generated in the molten resin, thereby further improving the plasticization and kneading of the molten resin.

[0076] Furthermore, the reaction force acting on the screw head 14A is reduced by the recessed groove 45, so the rotation speed of the screw 9 can be increased, and further, durability can be improved due to the reduced load.

[0077] Next, a third embodiment of the present invention will be described. Fig. 11 is an explanatory diagram showing a screw head 14B according to the third embodiment of the present invention, Fig. 12 is a view of the screw head 14B from the tip side, and Fig. 13 is an explanatory diagram showing a cross section of the screw head 14B. To avoid duplication of explanation, the same reference numerals are used for the same parts as in the above-described embodiments, and explanations will be omitted.

[0078] The screw head 14B has agitating blades 30B. The agitating blades 30B are formed so that the circumferential spacing between adjacent agitating blades 30B is narrower than that of the agitating blades 30A, and the circumferential thickness is also smaller. In other words, the screw head 14B has agitating blades 30B in which eight agitating blades 30A with reduced thickness are formed in the circumferential direction.

[0079] The grooves 31 formed in the screw head 14B are spaced closer together than the grooves 31 formed in the screw head 14A.

[0080] When the screw head 14B is rotated, the agitating blade 30B is divided into a front blade portion 50 and a rear blade portion 51 due to the presence of the recessed groove 45. When the agitating blade 30B rotates, an annular gap having the cross-sectional shape of the recessed groove 45 is formed between the molten resin agitated by the front blade portion 50 and the molten resin agitated by the rear blade portion 51.

[0081] Furthermore, the intervals between the grooves 31 are narrower than those of the screw head 14A, so the molten resin that enters the grooves 31 is dispersed more than in the screw head 14A.

[0082] At this time, the molten resin stirred by the stirring blade 30B is subjected to a torque that is more dispersed than that of the stirring blade 30A, and a more complex swirling flow is generated in the molten resin, thereby improving the plasticization and kneading of the molten resin.

[0083] In the above explanation, the injection stretch blow molding machine 1 that continuously performs the injection molding process, the blow molding process, and the removal process has been given as an example of the injection stretch blow molding machine, but the present invention is not limited to this. The present invention can also be used in an injection stretch blow molding machine that has a temperature adjustment process that adjusts the temperature of the injection-molded preform. [Explanation of symbols]

[0084] 1. Injection stretch blow molding machine 2 Injection molding section 3 Blow molding section 4. Removal section 9 Screw 12 Screw body 13 Seat ring 14 Screwhead (Torpedo) 14A screw head 14B screw head 15 Ring Valve 20 heads 21 Neck 22 Connecting part 30 stirring blades 30A stirring blade 30B stirring blade 31 Groove 40 Side wall 41 Top 42 Slope 43 Back 44 Intersection 50 Front wing 51 Rear wing

Claims

1. A substantially conical head; a neck portion integrally formed on one side of the head in the axial direction; a connecting portion integrally formed on one side of the neck portion in the axial direction, The head The head has a plurality of stirring blades that protrude radially outward from the axis of the head and are spaced apart in the circumferential direction, The stirring blade has a side wall surface extending along the radial direction and a top surface along the circumferential direction, The screw head is characterized in that the intersection of the side wall surface and the top surface forms an acute angle.

2. 2. The screw head according to claim 1, wherein a recessed groove is formed in the top surface along the circumferential direction.

3. A molten resin injection device comprising the screw head according to claim 1 or 2.

4. An injection stretch blow molding machine having at least an injection molding section that molds a preform, a blow molding section that stretches and blows the molded preform to form a hollow body, and a take-out section that sends the hollow body formed in the blow molding section out of the molding machine, the injection molding unit has an injection mold and an injection device that injects molten resin into the injection mold, The injection device A substantially conical head; a neck portion integrally formed on one side of the head in the axial direction; a connecting portion integrally formed on one side of the neck portion in the axial direction, The head The head has a plurality of stirring blades that protrude radially outward from the axis of the head and are spaced apart in the circumferential direction, The stirring blade has a side wall surface extending along the radial direction and a top surface along the circumferential direction, An injection stretch blow molding machine comprising a screw head, wherein the intersection of the side wall surface and the top surface forms an acute angle.

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