JP2019198993A - Injection molding machine and method for producing foam molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine and a method for manufacturing a foamed molded product, which enables foam molding using a low pressure raw material gas. An injection molding machine (1) has a sleeve member (20) embedded in a cylinder tip (12). The sleeve member 20 has a cylindrical portion 21 that partially constitutes the resin flow path 14 of the cylinder tip portion 12. The tubular portion 21 has a porous portion 25 through which gas can pass, and the cylinder tip portion 12 is provided with an introduction space 15 into which the raw material gas is introduced around the tubular portion 21. .. Then, when the raw material gas is introduced into the introduction space 15, the screw 30 is driven so that the pressure of the resin material P in the resin flow path 14 becomes higher than the pressure of the raw material gas. [Selection diagram] Fig. 7

Description

  The present invention relates to an injection molding machine for foam molding and a method for producing a foam molded article.

The present applicant discloses an example of a conventional injection molding machine for foam molding in Patent Document 1. This injection molding machine incorporates a sleeve in the heating cylinder head. The sleeve has a portion formed of a porous material, and a center hole that constitutes a part of the resin passage is formed in the portion. An introduction space for supercritical CO ₂ gas, N ₂ gas or the like (collectively referred to as “physical foaming agent”) is formed around the sleeve, and the physical foaming agent injected into the introduction space is porous. It is supplied into the resin passage through fine pores of the material.

JP 2012-232558 A

Such an injection molding machine pressurizes the source gas such as CO ₂ gas or N ₂ gas to about 20 to 30 MPa in order to generate a physical foaming agent in a supercritical state. However, it is difficult to control the supply amount of the physical foaming agent which is such a high-pressure fluid, and when the amount of the physical foaming agent varies, there is a problem that the quality of the molded product also varies. Moreover, since the pressure | voltage rise pump which makes source gas high pressure is needed, there exists a problem that an apparatus will become expensive.

  Then, an object of this invention is to provide the manufacturing method of the injection molding machine which enabled foam molding using the raw material gas of low pressure, and a foaming molding.

  In order to achieve the above object, an injection molding machine according to one aspect of the present invention is an injection molding machine for foam molding, and includes a cylinder, a screw accommodated in the cylinder, and rotation and forward / backward movement of the screw. A screw drive part to be embedded, and a sleeve member embedded in the tip part of the cylinder, the sleeve member has a cylindrical part partially constituting a resin flow path at the tip part of the cylinder, The cylindrical portion has a porous portion through which gas can pass, the tip of the cylinder is provided with an introduction space into which a source gas is introduced around the cylindrical portion, and the screw driving portion is When the source gas is introduced into the introduction space, the screw is driven so that the pressure of the resin material in the resin flow path becomes higher than the pressure of the source gas.

  According to the present invention, the sleeve member embedded in the tip portion of the cylinder has a cylindrical portion that partially constitutes the resin flow path. The cylindrical portion has a porous portion through which gas can pass, and the leading end portion of the cylinder is provided with an introduction space into which the source gas is introduced around the cylindrical portion. When the source gas is introduced into the introduction space, the screw is driven so that the pressure of the resin material in the resin flow path becomes higher than the pressure of the source gas. As a result, by increasing the pressure of the resin material in the resin flow path, the pressure of the raw material gas in the resin flow path also increases, so that it is possible to promote the impregnation and diffusion of the raw material gas into the resin material. . Therefore, foam molding using a source gas having a relatively low pressure is possible, and quality variations and apparatus costs can be suppressed.

  In the present invention, when the raw material gas is introduced into the introduction space, the screw driving unit is configured such that the pressure of the resin material in the resin flow path is the pressure at which the raw material gas is in a supercritical state in the resin flow path. It is preferable to drive the screw so that By doing in this way, it can further promote that a source gas will be in a supercritical state in a resin channel, and a source gas impregnates and diffuses into a resin material.

  In the present invention, it is preferable that when the source gas is introduced into the introduction space, the screw driving unit drives the screw so that the pressure of the resin material in the resin flow path is 20 to 40 MPa. By doing in this way, source gas will be in a supercritical state or a state close | similar to it in a resin flow path, and it can further accelerate | stimulate that source gas is impregnated and diffused in resin material.

  In the present invention, the screw driving unit drives the screw so that the pressure of the resin material in the resin flow path is lower than the pressure of the raw material gas before the raw material gas is introduced into the introduction space. It is preferable. By doing in this way, the source gas introduced into the introduction space can easily pass through the porous portion of the cylindrical portion of the sleeve member, and the source gas can be effectively supplied to the resin flow path.

  In the present invention, it further includes an opening / closing mechanism for opening / closing the outlet of the resin flow path, and the opening / closing mechanism is configured such that the pressure of the resin material in the resin flow path is controlled by the driving of the screw by the screw driving unit. It is preferred to close the outlet before it is raised above the pressure. By doing in this way, it can suppress that the resin material in a resin flow path flows out from an exit, and can make the pressure of the resin material in a resin flow path high effectively.

  In this invention, it is preferable that the said screw has a backflow prevention function which prevents the backflow of the said resin material at the time of inject | pouring the resin material in the said cylinder ahead. By doing in this way, the backflow of the resin material in a cylinder can be suppressed and the pressure of the resin material in a resin flow path can be made high effectively.

  In the present invention, it is preferable to further include a source gas supply unit that supplies a source gas introduced into the introduction space, and the source gas supply unit preferably has a maximum pressure of 3 to 7 MPa of source gas that can be supplied. By doing in this way, since the maximum pressure of the source gas which can be supplied is comparatively low, control of the supply amount of source gas becomes easy, and the dispersion | variation in the quality of a molded product can be suppressed. Moreover, the cost of the apparatus can be reduced by eliminating the need for a booster pump or the like that increases the pressure of the source gas.

  In order to achieve the above object, a method for producing a foamed molded product according to another aspect of the present invention includes a cylinder, a screw accommodated in the cylinder, a screw driving unit that rotates and advances the screw forward and backward, A sleeve member embedded in a tip portion of the cylinder, and the sleeve member has a cylindrical portion that partially constitutes a resin flow path of the tip portion of the cylinder, and the cylindrical portion is Manufacture of a foam molded body for use in an injection molding machine having a porous portion through which gas can pass and the leading end of the cylinder having an introduction space for introducing a raw material gas around the cylindrical portion The method is characterized in that when the raw material gas is introduced into the introduction space, the screw is driven to make the pressure of the resin material in the resin flow path higher than the pressure of the raw material gas.

  According to the present invention, by increasing the pressure of the resin material in the resin flow path, the pressure of the raw material gas in the resin flow path also increases, so that it is possible to promote the impregnation and diffusion of the raw material gas into the resin material. Therefore, foam molding using a source gas having a relatively low pressure is possible, and quality variations and apparatus costs can be suppressed.

  According to the present invention, foam molding using a low-pressure source gas is possible.

It is principal part sectional drawing of the injection molding machine which concerns on one Embodiment of this invention. It is a perspective view of the sleeve member which the injection molding machine of FIG. 1 has. It is a figure which shows the control part of the injection molding machine of FIG. 1, and each function part controlled by it. It is a figure explaining the plasticization operation | movement in the injection molding machine of FIG. It is a figure explaining the pressure reduction operation | movement in the injection molding machine of FIG. It is a figure explaining the pressurization operation | movement in the injection molding machine of FIG. It is a figure explaining the injection operation in the injection molding machine of FIG. It is a figure explaining the product taking-out operation | movement in the injection molding machine of FIG.

  Hereinafter, an injection molding system according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view illustrating a main part of an injection molding machine according to an embodiment of the present invention. FIG. 2 is a perspective view of a sleeve member included in the injection molding machine of FIG. FIG. 3 is a diagram showing a control unit of the injection molding machine of FIG. 1 and each functional unit controlled thereby. 4 to 8 are diagrams for explaining operations in the injection molding machine of FIG. 1, and correspond to a plasticizing operation, a pressure reducing operation, a pressurizing operation, an injection operation, and a product taking-out operation in this order. In the following description, “upper and lower” corresponds to the upper and lower sides of FIGS. 1 and 4 to 8. Further, “front and rear” means the front end side and the rear end side of the cylinder, and corresponds to the left and right in FIGS. 1 and 4 to 8.

The injection molding machine 1 for foam molding according to the present embodiment impregnates and diffuses a source gas such as CO ₂ gas or N ₂ gas into a cavity C of a mold K having a moving mold K1 and a fixed mold K2. The resin material P is injected to produce a product S that is a foam molded article.

  As shown in FIG. 1, the injection molding machine 1 includes a cylinder 10, a sleeve member 20, a screw 30, an opening / closing mechanism 40, and a raw material gas supply unit 50.

  The cylinder 10 has a cylindrical cylinder main body 11 and a cylinder front end portion 12 attached to the front end of the cylinder main body 11 (left side in FIG. 1). On the outer peripheral surface of the cylinder body 11, for example, a heating device 13 including a plurality of band heaters is provided. The heating device 13 may also be provided at the cylinder tip 12. The cylinder front end portion 12 is formed with a resin flow path 14 communicating with the cylinder body 11. A sleeve member 20 shown in FIG. 2 is embedded in the cylinder tip portion 12.

  The sleeve member 20 includes a cylindrical tubular portion 21 and circular flange portions 22 and 22 provided at both ends of the tubular portion 21. The cylindrical portion 21 is inserted in the middle of the resin flow path 14 so that the inner space 23 becomes a part of the resin flow path 14 of the cylinder tip portion 12. That is, the cylindrical portion 21 partially configures the resin flow path 14.

  The sleeve member 20 is obtained by laser processing metal powder (including alloy powder). When the metal powder is irradiated with a high level laser, the metal powder is completely dissolved and becomes a bulk material after solidification. On the other hand, when a low level laser is irradiated, only a part of the metal powder is melted and becomes a porous sintered metal after solidification.

  For example, a metal powder layer having a ring shape in a plane shape and a predetermined thickness is formed on a work table, and laser processing is performed. Then, by repeating the lamination of the metal powder layer in the thickness direction and the laser processing, the sleeve member 20 having a desired structure and shape can be obtained. Specifically, the metal powder layer is irradiated with a high level laser along the circumferential direction to make the entire circumferential direction a bulk material, or by irradiating a low level laser with the entire circumferential direction being a porous sintered metal. Can be. Alternatively, by alternately switching between a high level laser and a low level laser, the bulk material portion and the porous sintered metal portion can be formed so as to be alternately arranged in the circumferential direction. It can be set as a reinforcement structure by connecting to a direction or the circumferential direction. The porosity of the porous sintered metal can be adjusted by changing the laser power.

  In the present embodiment, the cylindrical portion 21 of the sleeve member 20 is formed by integrating a lattice-shaped bulk material portion 24 and a porous portion 25 made of a porous sintered metal disposed in the lattice of the bulk material portion 24. Have. By increasing the porous portion 25, the source gas can be efficiently supplied to the inner space 23 which is a part of the resin flow path 14. The porosity of the cylindrical portion 21 is 60%. The porosity of the cylindrical portion 21 is preferably 5% to 80%. If the porosity is less than 5%, the passage of the raw material gas is hindered and the raw material gas cannot be supplied sufficiently. Further, when the porosity is higher than 80%, the mechanical strength becomes a problem. The flange portions 22 and 22 are entirely bulk materials.

  The cylinder leading end portion 12 is provided with a cylindrical introduction space 15 into which the source gas is introduced around the cylindrical portion 21 of the sleeve member 20. Further, the cylinder front end portion 12 is provided with a pipe line 16 communicating with the introduction space 15. One end of the pipe line 16 is open to the upper surface of the cylinder front end portion 12, and a raw material gas supply unit 50 described later is connected thereto. An injection port 17 that is an outlet of the resin flow path 14 at the cylinder tip 12 communicates with a runner R formed in the fixed mold K2.

  As shown in FIG. 1, the screw 30 includes a screw main body 31 and a screw head 32 attached to the tip of the screw main body 31.

  The screw body 31 has a cylindrical shape, and a screw flight is provided on the outer peripheral surface. The rear end of the screw main body 31 (the end on the right side in FIG. 1, not shown) is connected to a screw drive unit 60 described later.

  The screw head 32 includes a conical (tapered) head portion 33, a cylindrical shaft portion 34 that is coaxially connected to the rear end of the head portion 33, a backflow prevention ring 35 for preventing backflow, a shaft portion 34, and a screw. And a circular sheet 36 provided between the main body 31 and the main body 31.

  The backflow prevention ring 35 has a cylindrical shape, and is formed so that the outer diameter is substantially the same as the inner diameter of the cylinder body 11 and the inner diameter is larger than the outer diameter of the shaft portion 34. The backflow prevention ring 35 has a shaft portion 34 inserted therein, and is movable in the front-rear direction with respect to the shaft portion 34. In other words, the backflow prevention ring 35 is fitted to the shaft portion 34 with play.

  The backflow prevention ring 35 forms an annular flow path 37 between the shaft portion 34. When the backflow prevention ring 35 moves forward with respect to the shaft portion 34, a gap is formed between the backflow prevention ring 35 and the seat 36. Thereby, the resin material can flow in the annular flow path 37. Further, when the backflow prevention ring 35 moves rearward with respect to the shaft portion 34, the backflow prevention ring 35 comes into contact with the seat 36 and there is no gap. Thereby, the flow (reverse flow) of the resin material to the rear in the annular flow path 37 is regulated. That is, the screw 30 has a backflow prevention function.

  The opening / closing mechanism 40 includes a valve body 41, a swing member 42, and an air cylinder 43. The valve body 41 is provided in the resin flow path 14 of the cylinder front-end | tip part 12 so that a movement in the front-back direction is possible. The swinging member 42 is pivotally attached to the cylinder front end portion 12 by a connecting pin 44 and has an upper end abutted against the rear end of the valve body 41 and a lower end portion connected to the air cylinder 43 by a connecting pin 45. The drive shaft 46 is rotatably attached. When the drive shaft 46 is pulled into the air cylinder 43, the valve body 41 is pushed by the upper end of the swing member 42 and moves forward, and the injection port 17 is closed. When the drive shaft 46 is pushed out from the air cylinder 43, the upper end portion of the swing member 42 moves rearward. The valve body 41 moves rearward by applying resin pressure as the screw 30 moves forward by the injection operation, and the injection port 17 is opened. In the configuration in which the mold K is provided with a gate valve, the opening / closing mechanism 40 may be omitted.

The source gas supply unit 50 is connected to the introduction space 15 through the pipe line 16 of the cylinder tip 12 and supplies a source gas such as CO ₂ gas or N ₂ gas to the introduction space 15. The source gas supply unit 50 includes a pressure adjustment unit 51 that adjusts the pressure of the source gas to be supplied, and a supply amount adjustment unit 52 that adjusts the supply amount of the source gas.

  The pressure adjusting unit 51 adjusts the pressure of the source gas so as to be a predetermined pressure. For example, when the pressure of the raw material gas stored in the gas cylinder is low, the pressure adjusting unit 51 is configured by a booster pump that raises the pressure to a predetermined pressure, or when the pressure of the raw material gas is high, the predetermined pressure is set. The configuration of the pressure adjusting unit is arbitrary, such as a pressure reducing valve that depressurizes the pressure. In the present embodiment, the pressure adjusting unit 51 is configured by a booster pump that increases the pressure of the source gas to 5 MPa. In the pressure adjusting unit 51, the maximum pressure of the source gas that can be supplied is preferably 3 to 7 MPa, and the maximum pressure is more preferably 5 MPa. For example, in the case of a booster pump, one having a boosting capacity of 3 to 7 MPa is preferable. By doing in this way, since the maximum pressure of the raw material gas which can be supplied is comparatively low, control of the supply amount of the raw material gas in the supply amount adjustment part 52 becomes easy, and the dispersion | variation in the quality of a molded product can be suppressed. In addition, the cost of the apparatus can be reduced by eliminating the need for a booster pump or the like that makes the raw material gas into a supercritical state. Note that the gas cylinder in which the source gas is stored may be directly connected to the introduction space 15. In this case, the gas cylinder valve corresponds to the source gas supply unit 50.

  As shown in FIG. 3, the injection molding machine 1 includes a screw drive unit 60, a mold clamping drive unit 70, and a control unit 80.

  The screw drive unit 60 includes, for example, a motor, a speed reduction mechanism, a ball screw mechanism, and the like. The screw drive unit 60 rotates and advances the screw 30 in the cylinder 10.

  The mold clamping drive unit 70, for example, bends and stretches a toggle link mechanism included in a mold clamping device (not shown), thereby moving a movable die plate (not shown) to which the movable mold K1 is attached to a movable die plate (not shown) to which the fixed mold K2 is attached. Advance and retract with respect to the fixed die plate. As a result, the movable mold K1 and the fixed mold K2 are closed and opened.

  The controller 80 controls the operation of the entire injection molding machine 1. The control unit 80 includes, for example, a microcomputer for an embedded device having a CPU, ROM, RAM, EEPROM, various I / O interfaces, and the like. The control unit 80 is connected to the heating device 13, the air cylinder 43, the source gas supply unit 50 (the pressure adjustment unit 51 and the supply amount adjustment unit 52), the screw drive unit 60, and the mold clamping drive unit 70. The control unit 80 controls each function unit in various operations such as a mold closing operation, a plasticizing operation (metering operation), a pressure reducing operation, a raw material gas supply operation, a pressurizing operation, an injection operation, a mold opening operation, and a product removing operation. Control.

  Next, an example of operation | movement which concerns on the manufacturing method of the foaming molding in the injection molding machine 1 of this embodiment is demonstrated.

  As a preparatory operation, the control unit 80 of the injection molding machine 1 controls the heating device 13 and the screw driving unit 60 to perform a purge operation until the molten resin material P stably flows out of the injection port 17.

  When the preparation operation is completed, as shown in FIG. 4, the control unit 80 controls the air cylinder 43 of the opening / closing mechanism 40 to move the valve element 41 forward by pulling the drive shaft 46 into the air cylinder 43. The injection port 17 is closed. Further, the control unit 80 controls the mold clamping drive unit 70 to clamp the movable mold K1 and the fixed mold K2 in a stacked manner (mold closing operation). In this state, the molten resin material P stays in the resin flow path 14 of the cylinder tip 12. Then, the control unit 80 controls the screw driving unit 60 to move the screw 30 backward while rotating it, and to plasticize (melt) the resin material P, the amount necessary for one injection is stored in the cylinder 10. To the space in front of the screw 30 (plasticizing operation). In this plasticizing operation, the screw 30 is retracted to the plasticizing end position L1 with respect to the reference position L0. In the present embodiment, the reference position L0 is defined as the boundary between the cylinder body 11 and the cylinder tip 12. However, for example, the previous injection end position may be set as the reference position L0, and the reference position L0 is optional depending on the device configuration. is there. In the present embodiment, the pressure of the resin material P in the resin flow path 14 at the end of the plasticizing operation is 10 to 15 MPa.

  Next, as shown in FIG. 5, the control unit 80 controls the screw driving unit 60 so that the pressure of the resin material P in the resin flow path 14 is the pressure of the source gas supplied from the source gas supply unit 50. The screw is driven so as to be lower (pressure reduction operation). In this decompression operation, the control unit 80 moves the screw 30 backward by the screw drive unit 60 so that the predetermined decompression target pressure is obtained while monitoring the pressure of the resin material P. As a result, the screw 30 is retracted from the plasticization end position L1 to the decompression position L2. In this embodiment, the pressure (target decompression pressure) of the resin material P in the resin flow path 14 at the end of the decompression operation is 2 to 3 MPa.

  Next, the control unit 80 controls the source gas supply unit 50 to increase the pressure of the source gas stored in a gas cylinder (not shown) by the pressure adjustment unit 51 and is necessary for one injection by the supply amount adjustment unit 52. A certain amount of source gas is measured and injected (supplied) into the introduction space 15 (source gas supply operation). In the present embodiment, the pressure adjusting unit 51 increases the pressure of the source gas to 5 MPa. The raw material gas injected into the introduction space 15 passes through the porous portion 25 of the cylindrical portion 21 of the sleeve member 20 and enters the resin flow path 14 (that is, the inner space 23). The raw material gas that has entered the resin flow path 14 contacts the resin material P staying in the resin flow path 14.

  Next, as shown in FIG. 6, when the control unit 80 controls the screw driving unit 60 to introduce the raw material gas into the introduction space 15, the pressure of the resin material P in the resin flow path 14 is changed to the raw material. The screw 30 is driven so as to be higher than the gas pressure (pressurizing operation). In this pressurizing operation, the control unit 80 advances the screw 30 by the screw driving unit 60 so as to reach a predetermined pressurization target pressure while monitoring the pressure of the resin material P. The pressurizing operation is performed before the injection operation (before opening the injection port 17). Thereby, the screw 30 is advanced from the decompression position L2 to the pressurization position L3. In the present embodiment, the pressure (target pressurization pressure) of the resin material P in the resin flow path 14 at the end of the pressurization operation is 20 to 40 MPa.

  In the pressurizing operation, when the raw material gas is introduced into the introduction space 15, the injection molding machine 1 drives the screw 30 to change the pressure of the resin material P in the resin flow path 14 of the cylinder tip 12 to the raw material. Set higher than gas pressure. When the pressure is increased in a state where the raw material gas is in contact with the resin material P, the pressure of the raw material gas is also increased, and impregnation and diffusion into the resin material P are promoted. In particular, by setting the pressure of the resin material P to 20 to 40 MPa, the raw material gas is brought into a supercritical state or a state close thereto in the resin flow path 14, and further impregnation and diffusion into the resin material P are promoted. In addition, it is preferable that the screw drive part 60 drives the screw 30 so that the pressure of the resin material P in the resin flow path 14 becomes a pressure at which the raw material gas becomes a supercritical state in the resin flow path 14. By doing in this way, source gas will be in a supercritical state in resin flow path 14, and it can further accelerate that source gas impregnates and diffuses in resin material P.

  After the predetermined diffusion time has elapsed, as shown in FIG. 7, the control unit 80 controls the air cylinder 43 of the opening / closing mechanism 40 to push the drive shaft 46 out of the air cylinder 43, thereby causing the swinging member 42. The upper end portion of the valve body 41 is moved rearward so that the valve body 41 can be moved rearward. The diffusion time is appropriately set according to the resin material P, the raw material gas, the target pressurization pressure, and the like. And the control part 80 controls the screw drive part 60, advances the screw 30, and injects the resin material P into the cavity C of the metal mold K (injection operation). As the screw 30 advances, resin pressure is applied to the valve body 41, the valve body 41 moves rearward, and the injection port 17 opens. In this injection operation, the screw 30 is advanced from the pressurization position L3 to the injection end position L4.

  Then, after the cavity C is filled with the resin material P by the injection operation, the control unit 80 controls the air cylinder 43 of the opening / closing mechanism 40 and pulls the drive shaft 46 into the air cylinder 43, whereby the valve body 41. Is moved forward to close the injection port 17. In this state, it waits for a predetermined curing time to elapse. After the resin material P is cured, as shown in FIG. 8, the control unit 80 controls the mold clamping drive unit 70 to open the movable mold K1 and the fixed mold K2 (mold opening operation), and an eject pin (not shown). To take out the product S from the cavity C (product take-out operation).

  Thereafter, the product S is molded by repeating the mold closing operation to the product taking-out operation.

  As described above, according to the injection molding machine 1 of the present embodiment, the sleeve member 20 embedded in the cylinder tip portion 12 has the cylindrical portion 21 that partially configures the resin flow path 14 of the cylinder tip portion 12. have. The cylindrical portion 21 has a porous portion 25 through which gas can pass, and the cylinder tip portion 12 is provided with an introduction space 15 into which the source gas is introduced around the cylindrical portion 21. . When the raw material gas is introduced into the introduction space 15, the screw 30 is driven so that the pressure of the resin material P in the resin flow path 14 becomes higher than the pressure of the raw material gas. Thus, by increasing the pressure of the resin material P in the resin flow path 14, the pressure of the raw material gas in the resin flow path 14 also increases, so that the raw material gas impregnates and diffuses in the resin material P. Can be promoted. Therefore, foam molding using a source gas having a relatively low pressure is possible, and quality variations and apparatus costs can be suppressed.

  Further, when the raw material gas is introduced into the introduction space 15, the screw driving unit 60 drives the screw 30 so that the pressure of the resin material P in the resin flow path 14 becomes 20 to 40 MPa. By doing in this way, source gas will be in a supercritical state or the state close | similar to it in the resin flow path 14, and it can further promote that a source gas impregnates and spread | diffuses in a resin material.

  In addition, the screw driving unit 60 drives the screw 30 so that the pressure of the resin material P in the resin flow path 14 is lower than the pressure of the raw material gas before the raw material gas is introduced into the introduction space 15. By doing in this way, the source gas introduced into the introduction space 15 can easily pass through the porous portion of the cylindrical portion 21 of the sleeve member 20, and the source gas can be effectively supplied to the resin flow path 14. it can.

  In addition, an opening / closing mechanism 40 for opening / closing the injection port 17 of the resin flow path 14 is further provided. The opening / closing mechanism 40 closes the injection port 17 before the pressure of the resin material P in the resin flow path 14 is increased from the pressure of the raw material gas by driving the screw 30 by the screw driving unit 60. By doing in this way, it can suppress that the resin material P in the resin flow path 14 flows out from the injection port 17, and can raise the pressure of the resin material P in the resin flow path 14 efficiently.

  Further, the screw 30 has a backflow preventing function for preventing backflow of the resin material P when the resin material P in the cylinder 10 is injected forward. By doing in this way, the back flow of the resin material P in the cylinder 10 can be suppressed during the pressurizing operation, and the pressure of the resin material P in the resin flow path 14 can be effectively increased.

  Moreover, it has further the raw material gas supply part 50 which supplies the raw material gas introduce | transduced into the introduction space 15, and the maximum pressure of the raw material gas which can supply the raw material gas supply part 50 is 5 MPa. By doing in this way, since the maximum pressure of the source gas which can be supplied is comparatively low, control of the supply amount of source gas becomes easy, and the dispersion | variation in the quality of a molded product can be suppressed. Moreover, the cost of the apparatus can be reduced by eliminating the need for a booster pump or the like that increases the pressure of the source gas.

  According to the injection molding machine 1 of the present embodiment, foam molding using a low-pressure source gas is possible.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these examples. Those in which those skilled in the art appropriately added, deleted, and changed the design of the above-described embodiments, and combinations of the features of the embodiments as appropriate, also include the present invention as long as they include the gist of the present invention. It is included in the scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Injection molding machine, 10 ... Cylinder, 11 ... Cylinder main body, 12 ... Cylinder front-end | tip part, 13 ... Heating device, 14 ... Resin flow path, 15 ... Introduction space, 16 ... Pipe line, 17 ... Injection port, 20 ... Sleeve 21: cylindrical part, 22 ... flange part, 23 ... inner space, 24 ... bulk material part, 25 ... porous part, 30 ... screw, 31 ... screw body, 32 ... screw head, 33 ... head part, 34 DESCRIPTION OF SYMBOLS ... Shaft part, 35 ... Backflow prevention ring, 36 ... Seat, 37 ... Annular flow path, 40 ... Opening / closing mechanism, 41 ... Valve body, 42 ... Swing member, 43 ... Air cylinder, 44, 45 ... Connecting pin, 46 ... Drive shaft 50 ... Raw material gas supply unit 51 ... Pressure adjustment unit 52 ... Supply amount adjustment unit 60 ... Screw drive unit 70 ... Mold clamping drive unit 80 ... Control unit K ... Mold, K1 ... Moving mold Mold, K2 ... fixed mold, C ... mold I, R ... runner, P ... resin material, S ... products, L0 ... reference position, L1 ... plasticized end position, L2 ... decompression position, L3 ... pressing position, L4 ... injection end position

Claims (8)

An injection molding machine for foam molding,
A cylinder,
A screw housed in the cylinder;
A screw drive for rotating and moving the screw forward and backward,
A sleeve member embedded in the tip of the cylinder,
The sleeve member has a cylindrical portion that partially configures the resin flow path at the tip of the cylinder,
The cylindrical portion has a porous portion through which gas can pass,
The leading end of the cylinder is provided with an introduction space into which the source gas is introduced around the cylindrical portion,
When the source gas is introduced into the introduction space, the screw driving unit drives the screw so that the pressure of the resin material in the resin flow path becomes higher than the pressure of the source gas. Injection molding machine.   When the raw material gas is introduced into the introduction space, the screw driving unit is configured such that the pressure of the resin material in the resin flow path becomes a pressure at which the raw material gas becomes a supercritical state in the resin flow path. The injection molding machine according to claim 1, wherein the screw is driven.   The screw drive unit drives the screw so that a pressure of a resin material in the resin flow path becomes 20 to 40 MPa when a raw material gas is introduced into the introduction space. The injection molding machine described in 1.   The screw driving unit drives the screw so that the pressure of the resin material in the resin flow path is lower than the pressure of the raw material gas before the raw material gas is introduced into the introduction space. The injection molding machine according to any one of claims 1 to 3. An opening / closing mechanism for opening / closing the outlet of the resin flow path;
The opening / closing mechanism closes the outlet before the pressure of the resin material in the resin flow path is increased above the pressure of the raw material gas by driving the screw by the screw driving unit. The injection molding machine according to claim 4.   The said screw has a backflow prevention function which prevents the backflow of the said resin material at the time of inject | pouring the resin material in the said cylinder forward, The any one of Claims 1-5 characterized by the above-mentioned. The injection molding machine described in 1. A source gas supply unit for supplying a source gas to be introduced into the introduction space;
The injection molding machine according to any one of claims 1 to 6, wherein the source gas supply unit has a maximum pressure of 3 to 7 MPa of source gas that can be supplied. A cylinder, a screw housed in the cylinder, a screw driving unit that rotates and advances the screw, and a sleeve member embedded in a tip portion of the cylinder, the sleeve member including the cylinder It has a cylindrical part that partially constitutes the resin flow path of the tip part, the cylindrical part has a porous part through which gas can pass, and the tip part of the cylinder is around the cylindrical part A method for producing a foam molded article used in an injection molding machine provided with an introduction space into which a raw material gas is introduced,
When the raw material gas is introduced into the introduction space, the screw is driven to make the pressure of the resin material in the resin flow path higher than the pressure of the raw material gas. .

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