JP2012232558A - Injection device of foam injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly diffuse physical foaming agent to molten resin stored in a metering resin reservoir part, and to prevent the physical foaming agent supplied to the metering resin reservoir part from flowing to a screw body side.SOLUTION: A sleeve at least a part of which is formed by a porous material and has a center hole constituting a part of a resin passage in the portion formed by the porous material, is incorporated in a heating cylinder head. An introduction space for the physical foaming agent is formed in an outer peripheral portion of the sleeve. A physical foaming agent supply nozzle is mounted on the heating cylinder head. The physical foaming agent supplied from the nozzle is injected into the introduction space for the physical foaming agent. The physical foaming agent injected into the introduction space is supplied to the inside of the resin passage opened in the heating cylinder head through fine holes provided in the porous material.

Description

  The present invention relates to an injection apparatus of an injection molding machine for foam molding, and more particularly, to a configuration of a physical foaming agent introducing portion provided in a heating cylinder.

Conventionally, as an injection molding machine for foam molding using a supercritical fluid as a foaming agent, a screw having a check ring for backflow prevention attached to the front end side, and an injection in which the screw is rotatably and retractable Foam for injecting supercritical CO ₂ gas, N ₂ gas or the like (collectively referred to as “physical foaming agent” in this specification) into the cylinder for measurement and the metering resin reservoir of the injection cylinder. And an injection device for injecting a physical foaming agent into the weighing resin reservoir from a plurality of positions from the front side to the rear side of the weighing resin reservoir. (For example, refer to FIGS. 2 to 6 of Patent Document 1).

  The injection device described in Patent Document 1 injects a physical foaming agent into the metering resin reservoir in front of the set position of the check ring provided on the tip end side of the screw, so that it is behind the set position of the check ring. The diffusion of the physical foaming agent into the existing molten resin can be suppressed, and the homogeneity of the molded product molded for each shot can be improved as compared with the case where no check ring is provided.

JP 2008-1015 A

  By the way, in the injection molding machine for foam molding, the diffusion of the physical foaming agent to the molten resin stored in the metering resin reservoir is speeded up to shorten the shot cycle and thus improve the productivity of the foam molded product. In addition, it is particularly required to completely prevent the physical foaming agent from diffusing into the molten resin existing behind the set position of the check ring and to improve the homogeneity of the molded product.

  That is, the injection molding machine for foam molding has a longer time for uniformly diffusing the physical foaming agent in the molten resin than a normal injection molding machine (an injection molding machine other than the injection molding machine for foam molding). Since it takes extra, the shot cycle becomes longer. For this reason, in order to increase the productivity of the foam molded product, shortening the time for uniformly diffusing the physical foaming agent in the molten resin is one of the most important matters. However, the injection molding machine described in Patent Document 1 is configured to inject a physical foaming agent in a dotted manner from a plurality of positions from the front side to the rear side of the metering resin reservoir, and a large amount of physical foaming agent from one injection unit. Must be diffused into the molten resin, it is difficult to rapidly diffuse the physical foaming agent into the molten resin.

  Further, since the injection device described in Patent Document 1 includes a check ring, the physical foaming agent is less likely to diffuse into the molten resin present on the rear side of the screw as compared to a case where the check ring is not provided. However, since no consideration is given to the back flow of the molten resin and the physical foaming agent from the front side to the rear side of the check ring during suck back, the molten resin is present behind the set position of the check ring. The diffusion of the physical foaming agent cannot be completely prevented.

  Hereinafter, this point will be described in detail. A conventionally known general check ring for preventing backflow is capable of moving forward and backward by a predetermined amount on a small-diameter neck provided between a screw head and a screw body and rotating. The structure is loosely fitted. Then, by rotating the screw in the plasticizing direction of the resin, when the check ring is positioned forward due to the resin pressure of the molten resin fed forward from the screw main body side, the check ring is on the screw main body side. A molten resin passage is formed between the check ring and the check sheet, and the molten resin passes through this passage, and the molten resin passes through the metering resin on the front side of the screw head. It is sent into the reservoir. In addition, in the injection stroke after the completion of the metering, the screw is rapidly advanced to inject and fill the molten resin stored in the front side of the screw into the mold. Due to the differential pressure between the resin pressure on the side and the resin pressure on the screw body side that is lowered by the rapid advance of the screw, the check ring immediately moves backward, and the check ring moves to a closed state in close contact with the check sheet. The reverse flow of the molten resin from the front side of the screw to the screw body side is prevented.

  By the way, if the resin pressure of the molten resin stored on the front side of the screw is high after the metering is completed, a drooling phenomenon in which the molten resin droops from the nozzle at the tip of the heating cylinder occurs. It is often performed to reduce the resin pressure on the front side of the screw by performing a suck-back operation of retreating to the front.

  However, when the suck back operation is performed, the resin pressure on the screw front side is reduced due to the forced retraction of the screw, and the check ring moves to the screw head side. The amount of resin that has been changed fluctuates in the weight of the molded product. In addition, in an injection molding machine of the type in which a physical foaming agent is injected into the front side of the screw head, the physical foaming agent flows back together with the molten resin through the molten resin passage to the screw body side. The physical foaming agent cannot be prevented from diffusing into the molten resin present in If the physical foaming agent diffuses into the molten resin existing on the screw body side, it becomes difficult to diffuse an appropriate amount of the physical foaming agent into the molten resin in the metering resin reservoir, and the physical foaming agent diffuses for each shot cycle. The amount becomes unstable, and it becomes difficult to stably mold a good product.

  The present invention has been made to solve such problems of the prior art, and its purpose is to expedite the diffusion of the physical foaming agent into the molten resin stored in the metering resin reservoir, and to perform foam molding. An injection device for foam molding that can improve the productivity of products and prevent the backflow of the physical foaming agent supplied to the metering resin reservoir to the screw body side and can stably mold high-quality foam molded products Is to provide.

  In order to solve the above-mentioned problems, the present invention provides a screw having a check ring mechanism for preventing a backflow on the tip side, a heating cylinder having a heating cylinder head at the tip, and an injection nozzle connected to the heating cylinder head. And a physical foaming agent supply nozzle for supplying a physical foaming agent into a resin passage established in the heating cylinder head, and stored in a weighing resin reservoir that extends from the tip of the screw to the tip of the injection nozzle. In an injection apparatus for molding a required foamed molded article by injecting and filling a mixture of the molten resin and the physical foamed material into a mold cavity, at least a part of the heating cylinder head has a porous material. A sleeve formed with a center hole forming a part of the resin passage is incorporated in a portion formed with the porous material, and a physical foaming agent is introduced into the outer peripheral portion of the sleeve. The physical foaming agent supply nozzle is attached to the heating cylinder head, the physical foaming agent supplied from the nozzle is sprayed into the physical foaming agent introduction space, and the physical foaming agent is sprayed into the introduction space. The physical foaming agent is supplied into a resin passage established in the heating cylinder head through fine pores of the porous material.

  When a sleeve having a center hole that forms part of the resin passage is built in the heating cylinder head and a space for introducing a physical foaming agent is formed in the outer peripheral portion of the sleeve, the physical foaming agent supplied from the physical foaming agent supply nozzle is formed. The foaming agent can be spread in the introduction space in the surface direction of the sleeve, and at least a part of the sleeve is formed from a porous material, and a center hole is opened in the portion formed with the porous material. The physical foaming agent spread in the surface direction of the sleeve in the space is uniformly ejected little by little through the fine holes of the porous material from the entire circumference of the center hole to the molten resin stored in the metering resin reservoir. Can be made. Therefore, the physical foaming agent can be diffused uniformly and easily into the molten resin, and the time required for the physical foaming agent to be diffused can be shortened. As a result, the shot cycle at the time of molding can be shortened, and the productivity of the foam molded product can be improved.

  According to the present invention, in the injection device having the above-described configuration, the sleeve includes a cylindrical portion and a flange portion formed at one end thereof, and the entire cylindrical portion is sintered with a porosity of 5% to 60%. It is formed with a metal material.

  If the entire cylindrical part is made of porous sintered metal material, the physical foaming agent can be jetted into the metering resin reservoir through the entire sleeve, so that the diffusion rate of the physical foaming agent into the molten resin stored in the metering resin reservoir is the fastest. And the productivity of the foamed molded product can be optimized. Further, the porosity of the sleeve is closely related not only to the permeation performance of the physical foaming agent but also to the mechanical strength of the sleeve. When the porosity of the sleeve is 5% or less, The mechanical strength of the sleeve becomes a problem when the physical foaming agent is not ejected quickly and sufficiently and exceeds 60 percent. For this reason, by forming with a sintered metal material having a porosity of 5% to 60%, the permeation performance and mechanical strength of the physical foaming agent can be balanced.

  In the injection device having the above-described configuration, the sleeve includes a cylindrical portion and a flange portion formed at one end thereof, and only a part of the cylindrical portion has a porosity of 5% to 60%. It is formed with a porous sintered metal material.

  If the entire cylindrical portion is made of a porous sintered metal material, the physical foaming agent can be diffused better into the molten resin. However, depending on the porosity, the mechanical strength of the sleeve is poor. It will be enough. On the other hand, when only a part of the sleeve is formed of the porous sintered metal material and the other part is formed of the bulk material, the part formed of the porous sintered metal material is formed of the bulk material. Therefore, the mechanical strength of the sleeve can be increased while maintaining good physical foaming agent permeability.

  In the injection device having the above-described configuration, the check ring mechanism includes a check sheet fixed to the screw, and a check ring movable in a direction in close contact with or away from the check sheet. In the closed state in which the ring is in close contact with the check sheet, the molten resin cannot pass through the check ring mechanism, and in the open state in which the check ring is separated from the check sheet, the molten resin passes through the check ring mechanism. And a lock mechanism for forcibly bringing the check ring into close contact with the check sheet when the screw is sucked back.

  As described above, when a check ring having a lock mechanism is used, the physical foaming agent exceeds the check ring by supplying the physical foaming agent into the weighing resin reservoir after the check ring is brought into close contact with the check sheet by the lock mechanism. Thus, diffusion into the molten resin stored on the screw body side can be prevented. Therefore, the diffusion state of the physical foaming agent in the mixture injected into the mold cavity for each shot can be made uniform, and a homogeneous molded body can be obtained. Further, by performing appropriate pressure management and temperature management, it is possible to easily increase the expansion ratio and reduce the average cell diameter.

  According to the present invention, in the injection device configured as described above, the screw includes a screw main body having a screw groove formed on an outer peripheral surface thereof, a screw head attached to a distal end portion of the screw main body, the screw main body, and the screw head. A small-diameter neck portion to which the check ring mechanism is attached, and the lock mechanism is provided at a rear end of the screw head and protrudes toward the check ring, The check ring includes a storage recess of the locking claw portion provided at an end of the screw head side of the check ring, and a locking portion that is continuous with the storage recess and protrudes toward the screw head. Is rotating in the direction of feeding the front, the locking claw is fitted into the storage recess, and the check When the cling is separated from the check sheet fixed to the tip end portion of the screw body and the screw is rotated backward by a predetermined amount from this state, the end surface of the locking claw portion rides on the end surface of the locking portion, The check ring is forcibly adhered to the check sheet.

  Suckback is an operation to retract the screw without rotating in any direction, so the end surface of the locking claw formed on the screw head is the locking formed on the end of the check ring on the screw head side. Even if the check ring rides on the end face of the part and the check ring is in close contact with the check sheet, the end face of the engaging claw part and the end face of the engaging part are maintained and the check ring is checked. Keeps in close contact with the sheet. For this reason, even if the resin pressure that presses the screw head forward from the screw main body side becomes larger than the resin pressure on the front side of the screw head, the screw main body is lowered by the suck back. The molten resin does not flow into the metered resin reservoir through the check ring from the side, and variations in the metered resin amount can be reduced. Further, the physical foaming agent can be prevented from diffusing from the metering resin reservoir to the screw body side.

  The present invention incorporates a sleeve in which at least a part is formed with a porous material in the heating cylinder head, and a center hole that constitutes a part of the resin passage is formed in the part formed with the porous material, A space for introducing a physical foaming agent is formed in the outer peripheral portion of the sleeve, the physical foaming agent supply nozzle is attached to the heating cylinder head, and the physical foaming agent supplied from the nozzle is injected into the physical foaming agent introduction space. Therefore, the physical foaming agent injected into the introduction space can be supplied in a planar shape from the periphery of the center hole into the molten resin stored in the metering resin reservoir, and the physical foaming agent can be diffused into the molten resin. It can be performed uniformly and quickly. Therefore, the time required for the diffusion of the physical foaming agent can be shortened, the shot cycle at the time of molding can be shortened, and the productivity of the foamed molded product can be improved.

It is principal part sectional drawing of the injection device which concerns on embodiment. It is AA sectional drawing of FIG. It is the figure seen from the injection nozzle side of the injection device concerning an embodiment. It is a longitudinal cross-sectional view of the sleeve which concerns on embodiment. It is a perspective view which shows the other example of the sleeve which concerns on embodiment. It is principal part sectional drawing which shows the state at the time of the screw normal rotation of the check ring which concerns on embodiment. It is principal part sectional drawing which shows the state at the time of screw reversal of the check ring which concerns on embodiment.

  As shown in FIG. 1, the injection apparatus according to the embodiment is a so-called inline screw type injection apparatus, and includes a screw 1, a heating cylinder 2 that houses the screw 1 so as to be capable of moving forward and backward, and a heating cylinder 2. A physical foaming agent supply device 3 for supplying a physical foaming agent and an injection nozzle 4 connected to the tip of the heating cylinder 2 are provided.

  The screw 1 includes a screw main body 11 having a screw groove 11a formed in a spiral shape on the outer surface, a screw-type screw head 12 attached to the tip of the screw main body 11, and a space between the screw main body 11 and the screw head 12. It comprises a check ring 13 for backflow prevention that is loosely fitted in a small-diameter neck so as to be able to move forward and backward, and a check sheet 14 fixed to the end of the screw body 11.

  As shown in more detail in FIGS. 6 and 7, a locking claw portion 12 a that protrudes toward the check ring 13 is formed at the rear end portion of the screw head 12, and an axial direction is formed on the outer peripheral surface of the screw head 12. Parallel grooves 12b are formed. On the other hand, at the end of the check ring 13 on the screw head 12 side, there are a recess 13a capable of accommodating the locking claw portion 12a, a locking portion 13b projecting to the screw head 12 side connected to the recess 13a, and these recesses. A tapered surface 13c provided between 13a and the locking portion 13b, a flat sealing surface 13d that is in close contact with the check sheet 14, and a resin passage 13e that penetrates the check ring 13 in the axial direction are formed. The above-described locking claw portion 12a, recess 13a, and locking portion 13b constitute a lock mechanism that forcibly contacts the check ring 13 with the check sheet 14.

  That is, when the screw 1 is rotating in the direction in which the molten resin is fed forward, as shown in FIG. 6, the locking claw portion 12 a formed on the screw head 12 is formed in the concave portion 13 a formed on the check ring 13. The check ring 13 moves forward due to the pressure of the molten resin fed forward from the screw main body 11 side, so that the locking claw portion 12a of the screw head 12 is a concave portion of the check ring 13. It will be in the state fitted in 14a. In this state, since the check ring 13 is separated from the check sheet 14, a resin passage is formed between the seal surface 13 d of the check ring 13 and the check sheet 14.

  When the screw 1 is rotated backward by a predetermined amount from this state, the locking claw portion 12a of the screw head 12 is guided by the tapered surface 13c of the check ring 13 and rides on the locking portion 13b of the check ring 13. As a result, the check ring 13 is pushed backward, and as shown in FIG. 7, the check ring 13 is in close contact with the check sheet 14, and the resin passage formed in the screw head 12 and the check ring 13 is blocked. The check ring 13 is held between the screw head 12 and the check sheet 14 and is restrained from moving in the front-rear direction.

  In a state where the locking claw portion 12a of the screw head 12 rides on the locking portion 13b of the check ring 13, the locking claw portion 12a of the screw head 12 and the check ring 13 are shown in FIG. Since the locking portions 13b are in contact with each other on the flat surfaces, even if the axial thrust due to the resin pressure acts on the check ring 13, the rotational direction relative to the check ring 13 There is no risk of component force acting. Accordingly, the suck back is performed from the state shown in FIG. 7, the resin pressure on the front side of the screw head 12 is lowered, and the resin pressure that presses the screw head 12 forward from the screw body 11 side is the resin on the front side of the screw head 12. Even if the pressure becomes larger than the pressure, the check ring 13 rotates and the locking portion 13b of the check ring 13 does not come off from the locking claw portion 12a of the screw head 12, and the check ring 13 is securely in contact with the check sheet 14. Maintained.

  The heating cylinder 2 includes a heating cylinder main body 21 that accommodates the screw 1 so as to be capable of moving forward and backward and rotatable, and a heating cylinder head 22 attached to a distal end portion of the heating cylinder main body 21. A sheathed heater 23 is wound around the outer surface of the heating cylinder head 22, and the molten resin that is melted by rotating the screw 1 and transferred to the front end side of the heating cylinder body 21 can be kept at a predetermined temperature. It is like that. Reference numeral 23 a in FIG. 2 indicates a power cord connected to the sheathed heater 23. A band heater 33 is wound around the outer surface of the heating cylinder main body 21 so that the raw material resin pellets supplied into the heating cylinder main body 21 from a hopper (not shown) can be heated. The raw material resin pellets supplied from the hopper into the heating cylinder body 21 are melted by the heating by the band heater 33 and the shearing heat generated by rotating the screw 1.

  As shown in FIG. 1, the heating cylinder head 22 is formed in a cylindrical shape, and one end of the heating cylinder head 22 is screwed to the distal end portion of the heating cylinder main body 21. A conical screw head insertion portion 24 for inserting the tip portion of the screw head 12 and a resin passage extending from the tip portion (bottom portion) to the other end side of the heating tube head 22 at the center of the heating tube head 22. 25, a sleeve insertion portion 26 having a diameter larger than that of the resin passage 25, a space forming portion 27 having a diameter larger than that of the sleeve insertion portion 26, and an injection nozzle screwing portion 28 having a diameter larger than that of the space formation portion 27 in this order. Is formed. Further, a sensor mounting hole 29 communicating with the resin passage 25 is formed in the radial direction of the heating cylinder head 22, and a resin pressure detection sensor for detecting the resin pressure in the resin passage 25 is formed in the sensor mounting hole 29. 30 is attached. The injection nozzle screwing portion 28 is provided with a female screw for screwing the injection nozzle 3, and a male screw formed at one end of the injection nozzle 4 is screwed into the injection nozzle screwing portion 28.

  A sleeve 31 illustrated in FIGS. 4 and 5 is inserted into the sleeve insertion portion 26. As shown in these drawings, the sleeve 31 includes a cylindrical portion 31a and flange portions 31b and 31c formed at both ends thereof, and the distal end portion of the cylindrical portion 31a is inserted into the sleeve insertion portion 26, and the flange 31 By inserting the outer peripheral surface of the portion 31 b into the space forming portion 27, it is stably held in the sleeve 31. Thereby, an annular physical foaming agent introduction space 32 is formed on the outer periphery of the cylindrical portion 31a. The diameter of the through hole 31 c opened in the sleeve 31 is the same as the diameter of the resin passage 25 opened in the heating cylinder head 22, and the through hole 31 c constitutes a part of the resin passage 25.

  In the sleeve 31 shown in FIG. 4, the entire cylindrical portion 31a is formed of a porous sintered metal material having a porosity of 5% to 60%, and the flange portion 31b is formed of a bulk material. In FIGS. 4 and 5, the porous sintered metal material is represented by a dot pattern. Thus, if the whole cylindrical part 31a is formed with a porous sintered metal material, the physical foaming agent can be jetted into the metered resin reservoir through the entire cylindrical part 31a, so that the molten resin stored in the metered resin reservoir can be discharged. The diffusion speed of the physical foaming agent can be maximized, and the productivity of the foamed molded product can be optimized. Further, since the porosity of the cylindrical portion is 5% to 60%, the physical foaming agent can be quickly and sufficiently ejected into the molten resin, and the mechanical strength of the sleeve 31 can be kept appropriate. Can do.

  On the other hand, the sleeve 31 shown in FIG. 5 has a reinforcing portion 31d formed of a bulk material in the length direction and the circumferential direction of the cylindrical portion 31a, and only a portion surrounded by the reinforcing portion 31d is a hole. It is formed of a porous sintered metal material having a rate of 5% to 60%. In the sleeve 31 of this example, the reinforcing portion 31d made of a bulk material is formed on the cylindrical portion 31a. Therefore, the mechanical strength of the sleeve 31 is high and the durability is excellent.

  The sleeve 31 shown in FIGS. 4 and 5 can be manufactured by laser processing. That is, when high-level laser is irradiated to metal powder (including alloy powder), the metal powder is completely melted by the heat and solidified to become a bulk material, and when irradiated with low-level laser, the metal powder is heated by the heat. Since only a part of the metal powder is melted and becomes a porous sintered metal after solidification, the metal powder layer having a predetermined thickness is formed in a ring shape on the work table, and then the circumferential direction of the metal powder layer By irradiating a laser at an appropriate level along the line, the entire circumferential direction of the metal powder layer can be made into a porous sintered metal, or can be made into a bulk material. In addition, by appropriately switching the laser power with respect to the circumferential direction of the metal powder layer, it is possible to alternately form the porous sintered metal portion and the bulk material portion in the circumferential direction. Therefore, by repeating the lamination of the metal powder layers in the thickness direction and the laser irradiation of each metal powder layer, and finally performing a required finishing process, the sleeve 31 having a required shape can be manufactured. The porosity of the porous sintered metal can be adjusted by changing the laser power.

As shown in FIG. 1, the physical foaming agent supply device 4 includes a gas cylinder 41 for storing a source gas such as CO ₂ gas and N ₂ gas, and a source gas supplied from the gas cylinder 41 at a high temperature and a high pressure to perform physical processing in a supercritical state. A supercritical fluid generator 42 as a foaming agent, a physical foam material supply nozzle 43 that injects a physical foaming agent supplied from the supercritical fluid generator 42 into the introduction space 32, a supercritical fluid generator 42, and physical foaming. It comprises an on-off valve 45 provided in a pipe line 44 connecting the material supply nozzle 43.

  As shown in FIG. 2, the physical foam material supply nozzle 43 is attached at two locations around the sleeve 31. As is apparent from this figure, the two physical foam material supply nozzles 43 and the resin pressure detection sensor 30 are equally arranged with an angular interval of 120 °. The on-off valve 45 is opened and closed once for each shot of the injection molding machine provided with the injection apparatus according to the embodiment, and supplies a predetermined amount of physical foaming agent into the introduction space 32 through the physical foam material supply nozzle 43.

  The injection nozzle 5 includes a shut-off nozzle 51 that is screwed to the tip of the heating cylinder head 22 and a nozzle body 52 that is screwed to the tip of the shut-off nozzle 51. The shut-off nozzle 51 is for preventing drooling of the molten resin from the nozzle body 52 at the time of measurement. The shut-off nozzle 51 includes a valve body 54 built in the resin passage 53 and the valve body 54 at a predetermined timing. It has the valve body drive part 55 which drives to a direction. As shown in FIGS. 1 and 2, the valve body driving unit 55 is attached to the outer surface of the shut-off nozzle 51 with a downward U-shaped mounting bracket 57 and a lower end portion of the mounting bracket 57. The air cylinder 58 and the intermediate portion are rotatably connected to the shut-off nozzle 51 via the connecting pin 59, the upper end portion is in contact with the valve body 54, and the lower end portion is connected to the air via the connecting pin 60. The swing member 61 is rotatably connected to the drive shaft 58a of the cylinder 58.

  An insertion portion 62 of the valve body 54 and a nozzle hole 63 having a smaller diameter than that are concentrically formed in the nozzle body 52, and a connecting portion between the insertion portion 62 and the nozzle hole 63 has a valve body 54. A valve seat 64 to which the tip portion is pressed is formed.

  In the measuring step, the air cylinder 58 is driven, the drive shaft 58a of the air cylinder 58 is drawn into the main body, the swinging member 61 is rotated counterclockwise in the figure, and the valve body 54 is left in the figure. Moved in the direction. Thereby, the front-end | tip part of the valve body 54 is pressed against the valve seat 64, and the drooling from the nozzle main body 52 of the molten resin collected in the resin channel | path is prevented. In the injection process after the metering process, the air cylinder 58 is driven, the drive shaft 58a of the air cylinder 58 is projected out of the main body, the swinging member 61 is rotated clockwise in the figure, and the valve body 54 is shown in FIG. It is moved in the upper right direction. At this time, the valve body 54 moves to the right in the figure by the resin pressure in the insertion portion 62. Thereby, the front-end | tip part of the valve body 54 leaves | separates from the valve seat 64, and the molten resin stored in the resin reservoir part can be inject | poured and filled in the mold cavity which is not shown in figure by driving a screw forward.

  Hereinafter, the operation after suck back of the injection apparatus configured as described above will be described.

  When the suck back is completed, the air cylinder 58 is driven and the valve body 54 is pressed against the valve seat 64 to prevent drooling of the molten resin from the nozzle body 52. Therefore, the molten resin necessary for one-shot injection molding is stored in the molten resin reservoir formed by the resin passage from the tip of the screw head to the valve seat 64.

  After the screw is sucked back, the machine controller (not shown) opens the on-off valve 45 and supplies a predetermined amount of the physical foaming agent into the physical foaming agent introduction space 32 from the physical foaming material supply nozzle 43. Since the physical foaming agent supplied in the introduction space 32 spreads in the surface direction of the sleeve 31 in the introduction space 32, it passes through the fine holes of the porous material and enters the metering resin reservoir from the entire circumference of the center hole. A small amount is uniformly ejected into the stored molten resin. As a result, the physical foaming agent diffuses into the molten resin stored in the molten resin reservoir, and a raw material resin for foam molding is generated.

  Next, after the air cylinder 58 is driven to separate the valve element 54 from the valve seat 64, the screw is driven forward so that the raw material resin for foam molding in which the physical foaming agent is uniformly diffused into a mold cavity (not shown) is obtained. Injection and filling. Thereby, a required foaming molded product is injection-molded.

  As described above, in the injection device according to the embodiment, a part of the molten resin passage is formed of a porous material, and the physical foaming agent introduction space 32 is formed on the outer periphery thereof, so that it is stored in the molten resin reservoir. Further, the physical foaming agent can be diffused uniformly and easily into the molten resin, and the time required for the physical foaming agent to be diffused can be shortened. As a result, the shot cycle at the time of molding can be shortened, and the productivity of the foam molded product can be improved.

  The present invention can be used in an injection molding machine equipped with a screw type injection device.

  DESCRIPTION OF SYMBOLS 1 ... Screw, 2 ... Heating cylinder, 3 ... Physical foaming agent supply apparatus, 4 ... Injection nozzle, 11 ... Screw main body, 11a ... Screw groove, 12 ... Screw head, 12a ... Locking claw part, 12b ... Groove, 13 ... Check ring, 13a ... concave portion, 13b ... locking portion, 13c ... tapered surface, 13d ... sealing surface, 13e ... resin passage, 14 ... check sheet, 21 ... heating cylinder body, 22 ... heating cylinder head, 23 ... band heater, 24 ... Screw head insertion portion, 25 ... Resin passage, 26 ... Sleeve insertion portion, 27 ... Space forming portion, 28 ... Injection nozzle screwing portion, 29 ... Mounting hole of resin pressure detection sensor, 30 ... Resin pressure detection sensor, 31 ... Sleeve, 31a ... Cylindrical part, 31b ... Flange part, 31c ... Through hole, 32 ... Space for introducing physical foaming agent, 41 ... Gas cylinder, 42 ... Supercritical fluid generator, 43 ... Physical Foam material supply nozzle, 44 ... pipe, 45 ... open / close valve, 51 ... shutoff nozzle, 52 ... nozzle body, 53 ... resin passage, 54 ... valve body, 55 ... valve body drive unit, 56 ... bolt, 57 ... attachment Metal fitting, 58 ... Air cylinder, 59 ... Connection pin, 60 ... Connection pin, 61 ... Swing member, 62 ... Insertion part of valve body, 63 ... Nozzle hole, 64 ... Valve seat

Claims (5)

Screw having a check ring mechanism for backflow prevention on the tip side, a heating cylinder having a heating cylinder head at the tip, an injection nozzle connected to the heating cylinder head, and a resin established in the heating cylinder head A physical foaming agent supply nozzle for supplying a physical foaming agent into the passage, and mixing the molten resin and the physical foaming material stored in the weighing resin reservoir from the tip of the screw to the tip of the injection nozzle In an injection apparatus for injecting and filling a body into a mold cavity to form a required foamed molded body,
A sleeve in which at least a part is formed with a porous material in the heating cylinder head, and a center hole constituting a part of the resin passage is formed in the part formed with the porous material, is built in the sleeve. A physical foaming agent introduction space is formed in an outer peripheral portion of the heating cylinder head, the physical foaming agent supply nozzle is attached to the heating cylinder head, and the physical foaming agent supplied from the nozzle is injected into the physical foaming agent introduction space. The injection device is characterized in that the physical foaming agent injected into the introduction space is supplied into a resin passage established in the heating cylinder head through fine pores of the porous material.   The sleeve is composed of a cylindrical portion and a flange portion formed at one end thereof, and the entire cylindrical portion is formed of a sintered metal material having a porosity of 5% to 60%. 2. The injection device according to 1.   The sleeve is composed of a cylindrical portion and a flange portion formed at one end thereof, and only a part of the cylindrical portion is formed of a porous sintered metal material having a porosity of 5% to 60%. The injection device according to claim 1.   The check ring mechanism has a check sheet fixed to the screw, and a check ring that can move in a direction in close contact with or away from the check sheet, and in a closed state in which the check ring is in close contact with the check sheet, Disabling the flow of the molten resin that passes through the check ring mechanism, and in the open state in which the check ring is separated from the check sheet, enables the flow of the molten resin through the check ring mechanism, The injection device according to any one of claims 1 to 3, further comprising a lock mechanism that forcibly contacts the check ring with the check sheet during suck back.   The screw is formed between a screw main body having a screw groove formed on an outer peripheral surface, a screw head attached to a tip portion of the screw main body, the screw main body and the screw head, and the check ring mechanism The locking mechanism is provided at the rear end of the screw head, and is provided with a locking claw that protrudes toward the check ring, and an end of the check ring on the screw head side. A storage recess of the provided locking claw portion, a locking portion that is continuous with the storage recess and protrudes to the screw head side, and when the screw rotates in a direction to feed the molten resin forward, The locking claw is fitted into the storage recess, and the check ring is fixed to the tip of the screw body. When the screw is separated from the check sheet, and the screw is rotated backward by a predetermined amount from this state, the end surface of the locking claw portion rides on the end surface of the locking portion, and the check ring is forcibly applied to the check sheet. The injection device according to claim 4, wherein the injection device is in close contact.

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