JP2018103393A - Injection molding machine and injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine capable of suppressing a stringiness phenomenon and occurrence of a cold slug, and producing efficiently a resin molding.SOLUTION: An injection molding machine 1 for injecting a molten resin material 31 into a cavity of a predetermined mold to produce the resin molding comprises: a sprue lock pin 13 provided on a movable side metal mold 11 and disposed so that a part of a tip portion of the sprue lock pin protrudes into the cavity of a mold, and a valve pin 26 installed in a fixed side die 21 and having a part of the tip portion of the valve pin in order to open and close an injection port 21a for the molten resin material. The sprue lock pin and the valve pin are opposed to each other at the mating faces of the movable side mold and the fixed side mold, and the valve pin is disposed such that a part of the tip portion protrudes into the cavity of the mold when a part of the tip portion of the valve pin closes the injection port, as a result, a tip surface of the valve pin abuts against the tip surface of the sprue lock pin.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an injection molding machine and an injection molding method for producing a resin molded product by injecting a molten resin material into a cavity of a mold.

  Conventionally, in an injection molding machine that generates a resin molded product by injecting a molten resin material into a cavity (cavity) of a predetermined mold, after molding the predetermined resin molded product, the generated molded product is used as a mold. The mold is opened by moving the movable part for removal from the mold. Immediately before this mold opening, the injection port of the molten resin material is closed by the valve pin, and the tip of the valve pin protruding from the injection port is in close contact with a part of the resin molded product before solidification It has become.

  From this state, the movable part is moved to open the mold. At that time, when the movable mold (core side) moves away from the fixed mold (cavity side), the resin molded product before solidification In some cases, a phenomenon occurs in which the resin material before solidification extends so as to pull the yarn between one portion of the valve pin and the tip of the valve pin (hereinafter, this phenomenon is referred to as a “thread drawing phenomenon”).

  When such a stringing phenomenon has occurred, if a valve is opened and closed to inject a molten resin material (shot) to form the next molded product, the stringing due to the stringing phenomenon that occurred in the previous shot will occur. There is a possibility that the resin adheres to the next product. In this case, a production defect occurs. In addition, when the stringing resin adheres to a contact surface of the mold, there is a possibility that a malfunction occurs in the mold.

  In view of this, in the conventional injection molding machine, various ideas for suppressing the yarn drawing phenomenon during mold opening have been proposed and implemented. For example, measures such as adjusting the timing for opening the mold by securing a sufficient cooling time until the thread pulling phenomenon does not occur can be considered.

  However, in this case, there is a problem in that good productivity cannot be obtained because the cycle time is extended in order to ensure a sufficient cooling time. In addition, the long cooling time reduces the temperature at the tip of the valve pin, resulting in cooling of the molten resin at the tip of the nozzle, which clogs the flow path, There is a possibility that a so-called cold slug, such as flowing to the exterior, may occur.

  Further, various proposals have been made by, for example, Japanese Patent Application Laid-Open Nos. 2009-196242 and 2004-136575.

  In the injection molding machine disclosed in the above Japanese Unexamined Patent Publication No. 2009-196242 and the like, the tip of the valve pin on the movable part side enters the sprue bush connected to the hot bush provided with a heater when the mold is closed, and the pin at the time of injection The tip end surface is spaced apart from the sprue inlet to open the sprue inlet, and at the end of injection, the pin tip end surface contacts the sprue inlet and closes the sprue inlet. As a result, the tip of the valve pin comes into contact with the sprue inlet when the mold is closed, so that the temperature of the valve pin rises moderately, so that the stringing phenomenon when the mold is opened can be suppressed.

  The injection molding machine disclosed by the above Japanese Patent Application Laid-Open No. 2004-136575 or the like has a temperature that can deform a predetermined range around a position (thread drawing occurrence position) corresponding to a valve gate of a molded product (generation of a thread drawing phenomenon). Temperature adjusting means for adjusting the temperature to a temperature not to be adjusted.

JP 2009-196242 A JP 2004-136575 A

  However, in the conventional configuration disclosed in Japanese Patent Application Laid-Open No. 2009-196242, Japanese Patent Application Laid-Open No. 2004-136575, etc., it is necessary to provide a sprue bush and temperature adjusting means, which complicates and enlarges the apparatus. There is a problem.

  The present invention has been made in view of the above-described points, and an object of the present invention is to perform a yarn drawing phenomenon in an injection molding machine that generates a resin molded product by injecting a molten resin material into a cavity of a mold. It is another object of the present invention to provide an injection molding machine and an injection molding method that can reliably prevent the occurrence of cold slug and can efficiently produce a resin molded product.

  In order to achieve the above object, an injection molding machine according to an aspect of the present invention is an injection molding machine that generates a resin molded product by injecting a molten resin material into a cavity of a predetermined mold, and is provided on a movable side mold. And a sprue lock pin disposed so that a part of the tip part protrudes into the cavity of the mold, and a valve pin provided on the fixed side mold, and a part of the tip part opens and closes the injection port of the molten resin material And the sprue lock pin and the valve pin are arranged to face each other on the mating surface of the movable side mold and the fixed side mold, and a part of the tip of the valve pin serves as the inlet. When in the closed state, the valve pin is arranged so that a part of the tip protrudes into the cavity of the mold, and the tip surface of the valve pin and the tip surface of the sprue lock pin are in contact with each other. ing

  An injection molding method according to an aspect of the present invention is an injection molding method in which a molten resin material is injected into a cavity of a mold to generate a resin molded product, and a valve pin is moved backward to open an injection port. An injection pressure-holding step of extruding the molten resin material and injecting and filling the molten resin material into the cavity through the runner portion, and advancing the valve pin to close the inlet, and the runner portion and the above A cooling step of cooling and solidifying the molten resin filled in the cavity, and in the cooling step, the tip end surface of the valve pin protrudes toward the runner portion side and is disposed opposite to the tip end surface of the valve pin. The tip surface of the sprue lock pin formed at least in the diameter of the tip portion is smaller than the diameter of the injection port is brought into contact with the tip surface of the valve pin.

  According to the present invention, in an injection molding machine that generates a resin molded product by injecting a molten resin material into a mold cavity, the occurrence of stringing phenomenon and cold slug is surely suppressed, and the resin molded product can be efficiently used. An injection molding machine and an injection molding method that can be generated can be provided.

The principal part expanded sectional view which expands and shows the main components of the injection molding machine of one embodiment of the present invention. 1 is an enlarged cross-sectional view of the main part of the portion indicated by [2] in FIG. 1 during the mold clamping process (mold closed state) of the injection molding machine of FIG. The principal part expanded sectional view of the site | part shown by [2] of FIG. 1 at the time of the injection pressure holding process (mold closing state) of the injection molding machine of FIG. 1 is an enlarged cross-sectional view of the main part of the portion indicated by [2] in FIG. 1 during the cooling process (mold closed state) of the injection molding machine in FIG. The principal part expanded sectional view of the site | part shown by [2] of FIG. 1 at the time of the mold opening process (mold opening state) of the injection molding machine of FIG. 1 is an enlarged cross-sectional view of the main part of the portion indicated by [2] in FIG. 1 is an enlarged cross-sectional view of the main part of the portion indicated by [2] in FIG. 1 when the sprue lock pin is returned after the extrusion process of the injection molding machine in FIG. The principal part expanded sectional view which expands and shows the main component part of the injection molding machine of the modification of one Embodiment of this invention

  The present invention will be described below with reference to the illustrated embodiments. Each drawing used in the following description is schematically shown. In order to show each component in a size that can be recognized on the drawing, the dimensional relationship and scale of each member are different for each component. May be shown. Therefore, the present invention is only in the illustrated form with respect to the quantity of each component described in each drawing, the shape of each component, the ratio of the size of each component, the relative positional relationship of each component, and the like. It is not limited.

[One Embodiment]
1-7 is a figure which shows one Embodiment of this invention. Among these, FIG. 1 is an enlarged cross-sectional view of a main part showing an enlarged main component part of an injection molding machine according to an embodiment of the present invention. 2 to 7 are enlarged cross-sectional views of the main part showing the part indicated by [2] in FIG. Each of FIGS. 2 to 7 shows each step of the operation in the injection molding machine according to the embodiment of the present invention. That is, FIG. 2 shows the mold clamping process before the injection pressure holding process of the injection molding machine (mold closed state). FIG. 3 shows the injection pressure-holding process of the injection molding machine (mold closed state). FIG. 4 shows a cooling process after the injection pressure holding process of the injection molding machine (mold closed state). FIG. 5 shows the mold opening process after the cooling process of the injection molding machine (mold opening state). FIG. 6 shows an extrusion process of the molded product of the injection molding machine (mold open state). FIG. 7 shows a state in which the sprue lock pin is returned after the extrusion process of the injection molding machine (mold open state).

  First, a schematic configuration of an injection molding machine according to an embodiment of the present invention will be briefly described below with reference to FIG. Note that the basic configuration of the injection molding machine of the present embodiment is substantially the same as the conventional one. Therefore, in the following description, the same configuration as that of the conventional injection molding machine will be described briefly, and the characteristic configuration unique to the injection molding machine of this embodiment will be described in detail.

  The injection molding machine 1 of the present embodiment generates a resin molded product by injecting and injecting a resin material melted by heating into a cavity (cavity) of a predetermined mold, and cooling and solidifying it. It is a device to do.

  The injection molding machine 1 includes a movable unit 10 and a fixed unit 20. Among these, the movable part unit 10 includes a movable mold 11, an ejector pin 12, a sprue lock pin 13, an eject plate 14 that is a movable plate, a guide pin 15, a movable side fixed base 16, and a movable part unit 10. It is mainly composed of a side hydraulic cylinder 17 and a pressing mechanism 18 and the like.

  The fixed unit 20 includes a fixed mold (cavity plate) 21, a fixed fixed base 22, a hot runner block 23, a fixed hydraulic cylinder 24, a heater 25, a valve pin 26, a plastic pin, The main unit is composed mainly of a unit 27, a hopper 28, a motor 29, a cylinder 30, and the like.

  In the movable unit 10, the movable side mold 11 is a convex mold that is provided on the movable unit unit 10 side and forms a part (projection portion) of the injection mold. The shape of the product and the shape of the runner portion are defined by the shape of the convex portion and the shape of the concave portion of the fixed mold 21 of the fixed unit 20. Further, as will be described later, the movable mold 11 is formed with a plurality of through-holes 11a for allowing a plurality of ejector pins 12 and sprue lock pins 13 to penetrate at predetermined sites.

  The ejector pins 12 are a plurality of cylindrical rod-like members provided for extruding the molded product stuck to the mold during an extrusion process in which the molded product (product) is separated and taken out from the mold. As will be described later, one end of the ejector pin 12 is fixedly supported by the eject plate 14. Further, the other end of the ejector pin 12 is disposed so as to penetrate the movable mold 11 through the through hole 11a and to protrude from the movable mold 11 toward the fixed mold 21 side. Yes.

  The sprue lock pin 13 is a cylindrical bar-like member provided to attract a molded product during the mold opening process. The tip portion of the sprue lock pin 13 has a flat surface on the most distal surface and is formed in a substantially conical convex shape as a whole. In this case, the diameter of the flat surface of the foremost surface (reference numeral D1 in FIG. 7) is set to be a predetermined size as will be described later (details will be described later).

  The sprue lock pin 13 is formed of a member having good thermal conductivity, such as a metal member. The sprue lock pin 13 has its tip opposed to the tip of the valve pin 26 provided on the fixed unit 20 side on the mating surface of the movable side mold 11 and the fixed side mold 21, and each pin. Are arranged so that their central axes substantially coincide.

  The sprue lock pin 13 also has the same function as the ejector pin 12. The sprue lock pin 13 is also fixedly supported by the eject plate 14 at one end, as will be described later. The other end of the sprue lock pin 13 penetrates the movable mold 11 through the through hole 11a, and a part of the tip protrudes from the movable mold 11 toward the fixed mold 21 side. It is arranged.

  The eject plate 14, which is a movable plate, transfers the driving force of the movable hydraulic cylinder 17 to the plurality of ejector pins 12 and the sprue lock pins 13 during an extrusion process for extruding a molded product and separating the product from the mold. It is a plate-like member that transmits simultaneously and moves the ejector pin 12 and the sprue lock pin 13 simultaneously in a predetermined direction.

  For this purpose, the eject plate 14 is connected to the movable hydraulic cylinder 17 via a pressing mechanism 18 and is configured to fix and support each end of the ejector pin 12 and the sprue lock pin 13. ing.

  Here, the moving direction of the eject plate 14 is the arrow X direction shown in FIG. The plane of the eject plate 14 is disposed in parallel to a plane that is substantially orthogonal to the moving direction (arrow X direction). A plurality of pins such as the ejector pin 12 and the sprue lock pin 13 are arranged at a predetermined interval on the plane of the eject plate 14. In this case, the central axis of each pin of the ejector pin 12 and the sprue lock pin 13 is arranged along the moving direction of the eject plate 14, that is, substantially orthogonal to the plane of the eject plate 14. ing.

  The guide pins 15 are a plurality of cylindrical rod-like members that regulate the movement direction of the eject plate 14 to be a predetermined direction (that is, the direction along the arrow X) and guide the movement of the eject plate 14. For this purpose, the eject plate 14 has a plurality of guide holes that penetrate the plurality of guide pins 15.

  Further, the plurality of guide pins 15 also have a function as a support member that supports the movable mold 11 so that the movable mold 11 is arranged at a predetermined position with a predetermined interval with respect to the movable fixed base 16. . For this purpose, the guide pin 15 is fixedly supported at one end with respect to the movable side fixed base 16 and the other end with respect to the movable side mold 11. In this case, the center axis of each guide pin 15 is arranged to be parallel to the arrow symbol X.

  The movable side fixed base 16 is a basic component of the movable unit 10. The movable side fixed base 16 is provided to support the movable side mold 11 with a predetermined interval via the guide pin 15. The movable side fixed base 16 supports a part of the pressing mechanism 18 (support shaft 18 a) for transmitting the driving force of the movable side hydraulic cylinder 17 to the eject plate 14.

  The movable hydraulic cylinder 17 is a drive unit for moving the eject plate 14 in the arrow X direction via the pressing mechanism 18. The movable hydraulic cylinder 17 is driven and controlled at a predetermined timing based on a control device (not shown) including a control circuit (not shown).

  The movable unit 10 configured as described above is movable in a direction parallel to the direction of the arrow X in FIG. 1 with respect to the fixed unit 20 by a drive unit (not shown) to open and close the mold. It is configured.

  On the other hand, in the fixed unit 20, the fixed side mold 21 is a concave mold that is provided on the fixed unit 20 side and for forming a part of the injection mold (recessed portion). The shape of the product and the shape of the runner portion are defined by the shape of the concave portion and the shape of the convex portion of the movable mold 11 of the movable unit 10. Further, as will be described later, a molten resin material 31 is applied to the fixed mold 21 toward a runner portion 33 in a cavity formed by the movable mold 11 and the fixed mold 21. There are a plurality of through-holes 21b for disposing an injection port 21a (see FIG. 2 and subsequent figures) for injection and injection, and a nozzle 23b that is connected to the injection port 21a and through which the valve pin 26 is inserted. Is formed.

  The fixed side fixed base 22 is a basic component of the fixed unit 20. The fixed-side fixed base 22 fixes and holds the fixed-side mold 21 and fixedly supports a part of the hot runner block 23 (near the nozzle 23b).

  The hot runner block 23 substantially coincides with the inlet 23a and the manifold 23a, which is a flow path when the molten resin material 31 flowing from the plasticizing unit 27 flows into the inlet 21a of the fixed mold 21. This is a structural block having a nozzle 23b provided with an injection port 23c (see FIG. 2 and subsequent figures), a heater 25, a valve pin 26, a plurality of fixed hydraulic cylinders 24, and the like.

  The fixed hydraulic cylinder 24 is a drive unit for opening and closing the injection port 23c and the injection port 21a by moving the valve pin 26 in a direction parallel to the arrow X in FIG. The fixed hydraulic cylinder 24 is driven and controlled at a predetermined timing based on a control device having a control circuit (not shown).

  The heater 25 is a heating device provided around the flow path (manifold 23a) of the molten resin material 31 and the nozzle 23b. In order to maintain a predetermined temperature of the molten resin material 31 inside the flow path (manifold 23a) and the nozzle 23b, the heater 25 is, for example, at a predetermined timing based on a control device including a control circuit (not shown). Drive controlled.

  The plasticizing unit 27 is a structural unit for performing a plasticizing action that melts the resin material by applying heat and pressure to make it substantially liquefied. The plasticizing unit 27 is provided with a cylinder 30 for plasticizing the resin material, a hopper 28 for charging the resin material, a motor 29 for driving the cylinder 30 and the like.

  The valve pin 26 is a plurality of cylindrical rod-shaped members for opening and closing the injection port 23c and the injection port 21a. The valve pin 26 is formed of a member having good thermal conductivity, such as a metal member. As described above, the valve pin 26 moves in a direction parallel to the arrow X in FIG. 1 by the driving force of the fixed hydraulic cylinder 24. Further, as described above, the tip of the valve pin 26 faces the tip of the sprue lock pin 13 provided on the movable unit 10 side on the mating surface of the movable mold 11 and the fixed mold 21. In addition, a plurality of pins are arranged so that the central axes of the pins substantially coincide. When the valve pin 26 is disposed at the closed position where the injection port 23c and the injection port 21a are closed (during the mold clamping process and the cooling process), a part of the tip of the valve pin 26 is a cavity ( In this state, the tip surface of the valve pin 26 is configured to come into contact with the tip surface of the sprue lock pin 13.

  The size settings of the tip surfaces of the sprue lock pin 13 and the valve pin 26 are as follows.

  That is, the diameter of the most distal portion of the sprue lock pin 13 (reference numeral D1 in FIG. 6) is formed to be smaller than the inner diameter (reference numeral D2 in FIG. 6) of the through hole 11a (D1 <D2). Further, the diameter (reference numeral D1 in FIG. 6) of the sprue lock pin 13 is formed to be smaller than the inner diameter (reference numeral D3 in FIG. 6) of the injection port 21a, that is, the outer diameter of the valve pin 26. (D1 <D3).

  Further, in the injection molding machine 1 of this embodiment, the sprue lock pin 13 and the valve pin 26 (that is, the through hole 11a, the injection port 23c, and the injection port 21a) are fixed to the movable mold 11 and the fixed portion. It arrange | positions in the runner part 33 among the cavities (cavity) formed with the side metal mold | die 21. FIG.

  As described above, in the injection molding machine 1 according to the present embodiment, the sprue lock pin 13 and the valve pin 26 are disposed opposite to each other on the mating surface of the movable mold 11 and the fixed mold 21 to clamp the mold. At the time of the process and the cooling process, the respective tip surfaces of both (the sprue lock pin 13 and the valve pin 26) are configured to contact each other. Therefore, by adopting this configuration, an unnecessary through hole 34 (see FIG. 7) is formed in the produced molded product.

  Therefore, in the present embodiment, the sprue lock pin 13 and the valve pin 26 are arranged in the runner portion 33 so that the through hole 34 is formed in the runner portion 33 that does not affect the resin molded product 32 (see FIG. 1). To be.

  Further, the arrangement of the sprue lock pin 13 and the valve pin 26 in the runner portion 33 can avoid the influence of heat on the molded product from the molten resin material filled in the cavity (cavity), and can dissipate heat. The effect of improving the properties can also be obtained. Other configurations are substantially the same as those of the conventional injection molding machine.

  The operation of the injection molding machine 1 of the present embodiment configured as described above will be briefly described below with reference to FIGS.

  First, an initial state when an injection molding process is started using the injection molding machine 1 of the present embodiment is shown in FIG. The initial state shown in FIG. 2 shows a mold clamping process in which the core-side movable mold 11 is brought into contact with the cavity-side fixed mold 21 (cavity plate) and clamped.

  In the injection molding machine 1 in this state (mold clamping process), as shown in FIG. 2, the valve pin 26 is disposed at a closed position where the injection port 23c and the injection port 21a are closed. That is, at this time, a part of the tip of the valve pin 26 closes the injection port 23c and the injection port 21a, and from the injection port 23c and the injection port 21a, the movable side mold 11 and the fixed side mold 21 are connected. Projecting into the cavity (cavity) formed by.

  On the other hand, in this state, a part of the tip of the sprue lock pin 13 also protrudes into the cavity (cavity) from the through hole 11a. The tip surface of the valve pin 26 and the tip surface of the sprue lock pin 13 are in contact with each other.

  Further, in this state, the inside of the cavity (cavity) formed by the movable side mold 11 and the fixed side mold 21 is not filled with anything and is in a simple gap state. On the other hand, the molten resin material 31 is filled in the nozzle 23 b of the hot runner block 23. At this time, the injection port 23 c of the nozzle 23 b is closed by the valve pin 26. Thereby, the molten resin material 31 in the nozzle 23b is not discharged from the injection port 23c.

  2, the stationary hydraulic cylinder 24 is driven by a control device (not shown), and the valve pin 26 moves in the direction indicated by the arrow X1 shown in FIGS. Then, the process proceeds to the state shown in FIG. 3, that is, the injection process and the pressure holding process (hereinafter simply referred to as the injection pressure holding process).

  In this state (injection pressure holding step), as shown in FIG. 3, the closed state of the injection port 23c and the injection port 21a by the valve pin 26 is released, and the injection port 23c and the injection port 21a are opened. Thereby, the molten resin material 31 is discharged from the injection port 23c of the nozzle 23b, and the molten resin material 31 flows into the runner part 33 in the cavity (cavity) (see the arrow sign [A] in FIG. 3). The portion up to where the resin molded product 32 (see FIG. 1) is formed is filled by the discharge pressure.

  In this way, when the filling of the molten resin material into the cavity (cavity) is completed in the injection boosting process of FIG. 3, the control device (not shown) then drives the fixed hydraulic cylinder 24 to drive the valve pin 26. Is moved in the direction of the arrow X2 shown in FIGS. Then, the state shown in FIG.

  In this state (cooling step), as shown in FIG. 4, the injection port 23 c and the injection port 21 a are closed by the valve pin 26. Then, by maintaining this state for a predetermined time, the molten resin material filled in the cavity (cavity) is cooled, and the resin material is solidified.

  As described above, in this state (cooling process), as shown in FIG. 4, the tip ends of the sprue lock pin 13 and the valve pin 26 are in the same manner as in the mold clamping process shown in FIG. The tip surfaces of the two (the sprue lock pin 13 and the valve pin 26) are in contact with each other at the contact surface 40.

  Here, the valve pin 26 is in the channel (manifold 23a) and the nozzle 23b in the hot runner block 23, and the channel (manifold 23a) and the nozzle 23b are melted by the heater 25 as described above. The material 31 is heated to an appropriate temperature that maintains a predetermined temperature. As a result, the valve pin 26 is always heated.

  Here, in the present embodiment, at the time of the cooling process, as shown in FIG. 4, a part of the tip of the valve pin 26 protrudes into the cavity, and the tip surface of the valve pin 26 is the sprue lock pin 13. It is comprised so that the contact surface 40 (refer FIG. 4) may contact | abut to the front end surface.

  With this configuration, the tips of the sprue lock pin 13 and the valve pin 26 are disposed in the molten resin material filled in the runner portion 33 during the cooling process in the injection molding machine 1 of the present embodiment. The molten resin material in the region is removed, and the tip surfaces of the sprue lock pin 13 and the valve pin 26 come into direct contact with each other.

  As described above, the sprue lock pin 13 is formed of a metal member having good thermal conductivity. Therefore, as described above, since the tip surfaces of the sprue lock pin 13 and the valve pin 26 are in direct contact with each other, the heat held on the valve pin 26 side is easily transferred to the sprue lock pin 13 side having no heat source. Will be conducted. Thereby, cooling of the tip portion of the valve pin 26 is promoted.

  In this state (cooling process), after a predetermined time has elapsed, the control device (not shown) drives the movable unit 10 by a drive unit (not shown), and moves the movable unit 10 to the fixed unit 20. In contrast, it is moved in the direction of arrow X3 in FIG. Then, the state shown in FIG.

  In this state (die opening process), as shown in FIG. 5, the movable part mold 10 and the fixed side mold 21 are moved by moving the movable part unit 10 in the arrow X3 direction with respect to the fixed part unit 20. Are separated and the mold is opened, and the sprue lock pin 13 and the valve pin 26 are separated from each other.

  Subsequently, when in this state (die opening process), the control device (not shown) drives the movable hydraulic cylinder 17 and moves the eject plate 14 in the direction of arrow X4 in FIG. Move. Then, the state shown in FIG.

  In this state (extrusion step), as shown in FIG. 6, the sprue lock pin 13 moves in the same direction as the eject plate 14 moves in the arrow X4 direction. Although not shown in FIG. 6, at this time, the plurality of ejector pins 12 are simultaneously moved in the same direction. Thereby, the solidified molded product (shown as the runner portion 33 in FIG. 6) is pushed out of the movable mold 11 and separated from the movable mold 11. Thereafter, the control device (not shown) drives the movable hydraulic cylinder 17 to move the eject plate 14 in the direction of arrow X5 in FIG. As a result, the sprue lock pin 13 moves in the same direction and returns to the original position as shown in FIG. Along with this, the molded product is detached from the sprue lock pin 13. Thus, the molded product is taken out from the injection molding machine 1.

  After the molded product is taken out in this manner, the control device (not shown) then drives the movable unit 10 by a drive unit (not shown) so that the movable unit 10 faces the fixed unit 20 side. To move. Thereby, the injection molding machine 1 returns to the state shown in FIG.

  As described above, according to the above-described embodiment, when the injection port 23c and the injection port 21a are closed by the valve pin 26 (during the mold clamping process and the cooling process), a part of the tip of the valve pin 26 is used. Is configured to protrude into a cavity formed by the movable mold 11 and the fixed mold 21. At the same time, the valve pin 26 and the sprue lock pin 13 are arranged to face each other on the mating surface of the movable side mold 11 and the fixed side mold 21, and both (sprue lock pin 13, valve pin) during the mold clamping process and the cooling process. 26) is configured such that the respective front end surfaces abut on the abutment surface 40. By adopting such a configuration, cooling of the tip end portion of the valve pin 26 can be promoted, and therefore the stringing phenomenon can be suppressed.

  Further, at the time of the mold clamping process and the cooling process, the tip of the sprue lock pin 13 is also configured to protrude into a cavity (cavity) formed by the movable mold 11 and the fixed mold 21. Yes. With this configuration, the working distance of the valve pin 26 can be reduced, thereby contributing to a reduction in the manufacturing cost of the device.

  Further, the tip of the valve pin 26 and the sprue lock pin 13 is configured to protrude into the cavity during the cooling process, thereby reducing the amount of resin in the cavity by the occupied area. Can do. Accordingly, the time required for cooling and solidifying the resin can be shortened and the cycle time can be shortened, so that the occurrence of cold slug can be suppressed and the productivity can be improved.

  In addition to this, the tip shape of the sprue lock pin 13 is further devised to form a substantially conical convex shape as a whole with a flat surface on the foremost surface, and the size of the tip surface is set to D1 <D2 and D1. By using <D3 (see FIG. 6), it is possible to secure a flow path of the molten resin material in the cavity (cavity). Therefore, this enables efficient production without adversely affecting the quality of the molded product.

  Further, since the sprue lock pin 13 and the valve pin 26 are arranged in the runner portion 33, unnecessary through holes 34 formed in the molded product by the respective tip surfaces of the sprue lock pin 13 and the valve pin 26 coming into contact with each other during the cooling process. Can be a region not affected by the resin molded product 32 (see FIG. 1). At the same time, by arranging the sprue lock pin 13 and the valve pin 26 in the runner portion 33, it is possible to avoid the influence of heat on the molded product from the molten resin material filled in the cavity (cavity). , Heat dissipation can be improved.

  In the above-described embodiment, an example is shown in which the movable hydraulic cylinder 17 is applied as a drive unit for moving the eject plate 14 in the direction indicated by the arrow X in FIG. Moreover, the example which applied the fixed side hydraulic cylinder 24 as a drive unit which moves the valve pin 26 in the direction parallel to the arrow symbol X of FIG. 1 is shown. However, each of the drive units is not limited to the above example (hydraulic cylinder), and other constituent units may be applied.

  Further, in the injection molding machine 1 of the above-described embodiment, as a mechanism for separating the valve pin 26 and the sprue lock pin 13, the sprue lock pin 13 is fixedly supported on the eject plate 14, and the eject plate 14 is pressed. Although the structure which is moved by the movable hydraulic cylinder 17 via the mechanism 18 is shown, the structure of the mechanism is not limited to the structure shown in the above-described embodiment. For example, a configuration as shown in FIG.

[Modification 1]
FIG. 8 is an enlarged cross-sectional view showing a main part of an injection molding machine, showing a modification of the embodiment of the present invention.

  The modification shown in FIG. 8 shows a different example of a mechanism for separating the valve pin and the sprue lock pin. The basic configuration of the injection molding machine 1A of this modification is substantially the same as the injection molding machine 1 of the above-described embodiment. Accordingly, the same components described in the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and only different portions are described in detail below.

  As shown in FIG. 8, in this modification, as a drive unit for moving the sprue lock pin 13 in the direction indicated by the arrow X in FIG. 8, a sprue lock is provided separately from the movable hydraulic cylinder 17 in the above embodiment. The only difference is that the pin driving hydraulic cylinder 41 is provided for each sprue lock pin 13.

  The sprue lock pin drive hydraulic cylinder 41 is a drive unit that is driven and controlled by a control device (not shown) and moves the sprue lock pin 13 forward and backward in the direction of the arrow X in FIG. 8 at a predetermined timing. Other configurations are the same as those of the above-described embodiment.

  Even with the configuration of Modification 1 described above, the same effects as those of the above-described embodiment can be obtained.

[Modification 2]
Further, as a configuration different from the configuration shown in the embodiment and the modification 1, a configuration in which the movable unit 10 is moved in a predetermined direction with respect to the fixed unit 20 by a drive unit (not shown) is used. May be.

  Even with such a configuration, the same effect as that of the above-described embodiment can be obtained.

[Modification 3]
Furthermore, as a configuration different from the configuration shown in the embodiment and the first and second modifications, the plasticizing unit 27 may be separated from the stationary mold 21, for example. In this case, the plasticizing unit 27 is configured to be driven and controlled by a predetermined driving unit.

  Even with such a configuration, the same effect as that of the above-described embodiment can be obtained.

  The present invention is not limited to the above-described embodiments, and it is needless to say that various modifications and applications can be implemented without departing from the spirit of the invention. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if several constituent requirements are deleted from all the constituent requirements shown in the above-described embodiment, if the problem to be solved by the invention can be solved and the effect of the invention can be obtained, this constituent requirement is deleted. The configured structure can be extracted as an invention. Furthermore, constituent elements over different embodiments may be appropriately combined. The invention is not limited by the specific embodiments thereof, except as limited by the appended claims.

DESCRIPTION OF SYMBOLS 1,1A ... Injection molding machine 10 ... Movable part unit 11 ... Movable side metal mold 11a ... Through-hole 12 ... Ejector pin 13 ... Sprue lock pin 14 ... Eject plate 15 ... Guide pin 16 ... Movable side fixed base 17 ...... Moveable side hydraulic cylinder 18 ...... Pressing mechanism 18 a ...... Support shaft 20 ...... Fixed part unit 21 ...... Fixed side mold 21 a ...... Injection port 21 b ...... Penetration part 22 ...... Fixed side Fixed base 23 ... Hot runner block 23a ... Manifold 23b ... Nozzle 23c ... Injection port 24 ... Fixed hydraulic cylinder 25 ... Heater 26 ... Valve pin 27 ... Plasticizing unit 28 ... Hopper 29 ... ... Motor 30 ... Cylinder 31 ... Molten resin 32 ... Resin molded product 33 ... Runner part 34 ... Through hole 40 ... Contact surface 41 ... Sprue lock pin Driving hydraulic cylinder

Claims (7)

In an injection molding machine for producing a resin molded product by injecting a molten resin material into a cavity of a predetermined mold,
A sprue lock pin provided on the movable side mold and disposed so that a part of the tip projects into the cavity of the mold;
A valve pin that is provided on the stationary side mold, and a part of the tip part opens and closes the injection port of the molten resin material;
Comprising
The sprue lock pin and the valve pin are disposed opposite to each other on the mating surface of the movable mold and the fixed mold,
When a part of the tip of the valve pin closes the inlet, the valve pin is disposed so that a part of the tip protrudes into the cavity of the mold, and the tip surface of the valve pin and the sprue An injection molding machine configured to be in contact with a front end surface of a lock pin.   When a part of the tip of the valve pin closes the inlet, a part of the tip of the valve pin is disposed so as to protrude from the runner part of the cavity of the mold. The injection molding machine according to claim 1, characterized in that: The sprue lock pin has a diameter at the tip that comes into contact with the valve pin.
So as to have a smaller diameter than the inner diameter of the through-hole inserted through the movable mold, and
The injection molding machine according to claim 1, wherein the injection molding machine is formed to have a smaller diameter than an inner diameter of the injection port. The sprue lock pin
The diameter D1 of the tip portion on the side in contact with the valve pin,
When the inner diameter D2 of the through hole inserted through the movable mold,
D1 <D2
And when the inner diameter D3 of the inlet is
D1 <D3
The injection molding machine according to claim 1, wherein the injection molding machine is formed as follows.   2. The injection molding machine according to claim 1, wherein the sprue lock pin also serves as an ejector pin for taking out a molded product.   The injection molding machine according to any one of claims 1 to 3, wherein the sprue lock pin is made of a heat conductive member. In an injection molding method for injecting a molten resin material into a mold cavity to produce a resin molded product,
An injection pressure holding step of retracting the valve pin to open the injection port, extruding the molten resin material from the injection port, and injecting and filling the molten resin material into the cavity through the runner part,
A cooling step of advancing the valve pin to close the inlet, cooling the solidified resin filled in the runner part and the cavity, and solidifying;
Have
In the cooling step, the tip surface of the valve pin protrudes toward the runner part,
The front end surface of the sprue lock pin, which is disposed to face the front end surface of the valve pin and at least the diameter of the front end portion is smaller than the inlet, is brought into contact with the front end surface of the valve pin. Injection molding method.

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