JP5143616B2 - Mold for plastic injection molding and valve applied thereto - Google Patents

Description

  The present invention relates to a plastic injection mold provided with a gas vent hole, a valve applied to the mold, and a volatile gas emitted from a molten resin filled in a cavity defined by the mold or the cavity It is possible to discharge a gas such as air existing inside the cavity through the vent hole, and the molten resin supplied to the cavity flows out of the cavity through the vent hole. It relates to a valve that can be prevented.

  Conventionally, the gas is discharged through the vent hole, which is a discharge hole for the volatile gas emitted from the molten resin injected and supplied to the cavity of the plastic injection mold or the air existing in the cavity, and through the vent hole. A valve mechanism for preventing leakage of the molten resin is proposed (see Patent Document 1 below).

  In the conventional valve mechanism, the vent hole to which the valve mechanism is applied is provided in an ejector pin for projecting a molded product molded in the cavity from the mold to the outside when the mold is opened. Yes. The gas vent hole extends the ejector pin in the axial direction and opens to both ends of the ejector pin. One open end of the vent hole, one open end facing the cavity, is a recess having an inner diameter larger than the other part of the vent hole, and the valve mechanism is provided in the recess. .

  The valve mechanism moves between a closed position for closing the valve seat and a closed release position for releasing the valve seat with the open end of the recess forming a part of the vent hole as a valve seat. And a biasing force exerted on the valve body so that the valve body is in the closing release position, and the valve body receives the pressing force of the molten resin filled in the cavity. And a spring member allowing movement from the closed release position to the closed position.

  According to the conventional valve mechanism, when the molten resin is supplied into the cavity of the mold, the volatile gas generated by the molten resin and the air existing in the cavity are caused by the valve seat of the valve and the spring member. From the gap with the valve body biased to the closing release position, the gas is exhausted to the outside of the mold through the gas vent hole, thereby degassing. Further, when the valve body of the valve mechanism receives a pressing force exceeding the spring force of the spring member due to the molten resin supplied into the cavity, the valve body is in the closed position against the spring force of the spring member. To close the valve seat. Thereby, the outflow of the molten resin through the vent hole is prevented.

  In the valve mechanism, when the mold is opened, the ejecting action of the ejector pin on the molded product molded in the cavity of the mold is the valve body in a state where the valve seat is closed, that is, the This is done via a valve body in the closed position. For this reason, during the extrusion operation of the molded body, the communication between the cavity and the vent hole is blocked.

  By the way, if the outside air can be introduced into the cavity through the vent hole during the extrusion of the molded product, the negative pressure state in the cavity can be eliminated and the pressure of the introduced outside air can be exerted on the molded body. This can reduce the mold release resistance.

  In order to make this possible, for example, the gas vent hole is provided not in the ejector pin but in the mold itself, and a valve seat is further disposed in the gas vent hole. It is conceivable to arrange a valve body and a spring member that function in the same manner as in FIG.

  According to this alternative, when the molded product in the cavity of the mold has a protruding action, which causes the molded product to move, the spring force of the spring member is in a position to close the valve seat. The valve body in the receiving state moves to the closing release position that opens the valve seat. As a result, outside air can be introduced into the cavity through a gap formed between the valve seat and the valve body.

However, in this alternative, a part of the molten resin that inevitably enters the gap between the valve seat and the valve body is solidified during the molding of the molded product in the cavity. The valve body is fixed to the valve seat through the solidified material generated by the above. As a result, when there is a protrusion with respect to the molded product at the time of mold opening, the valve body does not move away from the valve seat despite receiving the spring force of the spring member. There is a problem that the introduction of can not be realized.
Japanese Patent Laid-Open No. 7-112659

  An object of the present invention is to provide a valve capable of introducing outside air into a cavity through a gas vent hole of a mold when the mold is opened, and a mold including the valve.

(Characteristics of the invention according to claim 1)
The invention according to claim 1 relates to a valve provided in a mold for plastic injection molding for opening and closing a gas vent hole communicating with the cavity of the mold, and a valve seat disposed in the gas vent hole; A valve body that is held by the valve seat and is movable between a closed position for closing the valve seat and a closed release position for releasing the valve seat; and A spring member that exerts a biasing force so as to be in the closed release position and allows the valve body to move from the closed release position to the closed position under the pressing force of the molten resin filled in the cavity of the mold. Including. In the present invention, the valve body includes a protrusion or a depression for forming an undercut in a molded product molded in the cavity of the mold, and the valve body is in the mold opening when the valve body is It is possible to entrain the molded product from the closed position to the closed release position via the protrusions or depressions, and to separate the valve body from the molded product without damaging the molded product. It is a thing to do.

  According to the first aspect of the present invention, in plastic injection molding, the cavity defined by the mold and the vent hole are placed in communication with each other by opening and closing the vent hole provided in the mold. Can be left out of communication. The opening and closing of the gas vent hole is performed by closing and releasing the valve seat arranged in the gas vent hole by the valve body. The valve body is held by the valve seat so as to be movable between a closed position for closing the valve seat and a closed release position for releasing the closed valve, and is in the closed release position by a spring member. Energized as follows. When the valve body is in the closed release position, a gap exists between the valve body and the valve seat, and the cavity of the mold and the gas vent hole communicate with each other through the gap. It is burned. When the molten resin is pressurized and supplied into the cavity and receives pressure or pressure from the molten resin, the valve body moves to the closed position against the spring force of the spring member, and moves the valve seat. Close. Until the valve seat is closed, a gas composed of a volatile gas emitted from the molten resin supplied into the cavity, air in the cavity, or the like passes through a gap between the valve body and the valve seat. It is guided to the vent hole and comes out of the mold. By discharging these gases, the molten resin can be easily distributed into the cavity. The molten resin supplied into the cavity is prevented from flowing out of the gas vent hole by closing the valve seat as the valve body moves to the closed position.

  In the present invention, the valve body includes a protrusion or a depression. When the molten resin is filled into the cavity, the protrusion is embedded in a molded product that is a solidified product of the molten resin, thereby forming a concave undercut in the molded product. The recess accepts a part of the molded product and forms a convex undercut on the outside of the molded product. Due to the formation of the undercut, the valve body is integrated with the molded product through the protrusions or depressions, and the molded product is moved relative to the mold by an ejecting operation using an ejector pin when the mold is opened. The valve body is entrained in the molded product. That is, it is moved together with the molded product. Accordingly, the valve body is forcibly moved from the closed position to the closed release position, and the valve body and the valve seat are in a state of being fixed by the molten resin that has entered and solidified between them. However, it is possible to create a gap between the valve body and the valve seat so that the outside air can be introduced into the cavity from the vent hole. By introducing outside air into the cavity and exerting the pressure on the molded product in the cavity, it is possible to reduce the mold release resistance of the molded product with respect to the mold. When the relative movement of the molded product with respect to the mold is continued, the concave undercut of the molded product is pulled away from the protrusion of the valve body without damaging the molded product, or the convex shape of the molded product is removed. An undercut can be extracted from the recess of the valve body.

(Characteristics of the invention according to claim 2)
The invention according to claim 2 comprises the component of the invention according to claim 1, and the gas vent hole of the mold has a recess in which the valve seat is disposed, which opens to the cavity. Features.

  According to the invention which concerns on Claim 2, a part of said degassing hole can be made into the recessed part opened to the cavity of the said metal mold | die, and this can be made into the arrangement | positioning space of the said valve seat.

(Characteristics of the invention according to claim 3)
The invention according to claim 3 is provided with the constituent elements of the invention according to claim 1 or 2, and the protrusion of the valve body has an outer shape spreading toward the cavity, and the recess of the valve body has It has a tapered wall surface toward the cavity.

  According to the invention of claim 3, the projection has a divergent outer shape toward the cavity, and the depression has a tapered wall surface toward the cavity. The undercut, which is a part of the molded product, can be formed so that separation from the valve body is impossible unless an external force is applied.

(Characteristics of the invention according to claim 4)
The invention according to claim 4 comprises the constituent elements of the invention according to any one of claims 1 to 3, and is composed of a plurality of valve body parts arranged concentrically and adjacent to each other. The inner valve body portion can be seated on the outer valve body portion, the outermost valve body portion can be seated on the valve seat, and the plurality of valve body portions are The spring members may be engaged with each other so that a biasing force of the spring member is exerted from the inner valve body portion to the outer valve body portion.

  According to the invention of claim 4, the inner valve body portion can be seated on the outer valve body portion, and the outermost valve body portion can be seated on the valve seat. In addition to between the valve seat and the outermost valve body portion, a gap is also formed between the valve body portions so that the cavity and the gas vent hole communicate with each other. It is possible to obtain a gap having a larger area that enables gas discharge or introduction of a larger amount of outside air. The biasing force of the spring member for generating the gap is exerted on all the valve body parts by mutual engagement of the inner valve body part and the outer valve body.

(Characteristics of the invention according to claim 5)
The invention according to claim 5 is provided with the constituent elements of the invention according to claim 4, and at least one valve body portion has an inscription or an inscription for attaching a symbol to the surface of the molded product. And

  According to the fifth aspect of the invention, when the molten resin is filled in the cavity of the mold, the molten resin is pressed on the surface of the molded body after being released from the valve body part. The intaglio or positive impression remains. As the trace of the inscription or the inscription, for example, it can be set to be an arbitrary symbol made up of a number, a serial number, a code or the like representing a year or month.

(Invention of Claim 6)
The invention according to claim 6 relates to a mold for plastic injection molding, and includes the valve according to any one of claims 1 to 5.

  According to the invention according to claim 6, as in the case of the invention according to claim 1, in the plastic injection molding, the gas vent hole can be opened and closed with respect to the cavity defined by the mold. Is opened and closed by closing and releasing the valve seat disposed in the vent hole. The valve body is held by the valve seat so as to be movable between a closed position for closing the valve seat and a closed release position for releasing the closed valve, and is in the closed release position by a spring member. Energized as follows. Thereby, when the valve body is in the closed release position, a gap exists between the valve body and the valve seat, and the cavity of the mold and the gas vent hole communicate with each other through the gap. Put in condition. When the molten resin is pressurized and supplied into the cavity and receives pressure from the molten resin, the valve body moves against the spring force of the spring member to close the valve seat. . Until the valve seat is closed, the volatile gas generated by the molten resin supplied into the cavity, together with the air in the cavity, passes through the gap between the valve body and the valve seat and releases the gas. It is guided to the hole and comes out of the mold. By discharging these gases, the molten resin can be distributed into the cavity. The molten resin supplied into the cavity is prevented from flowing out of the vent hole due to the closing of the valve seat accompanying the movement of the valve body to the closing release position.

  In the present invention, the valve body includes a protrusion or a depression, and when the molded product is molded in the cavity, the projection is embedded in the molded product and a concave undercut is formed in the molded product. And the recess receives a portion of the molded product and forms a convex undercut on the exterior of the molded product. Due to the formation of the undercut, the valve body is integrated with the molded product through the protrusions or depressions, and when the mold product is opened, the valve body is moved relative to the mold. Entrained to the molded product, that is, moved together with the molded product. As a result, the valve body is forcibly moved from the closed position to the closed release position, and the valve body and the valve seat enter between them and are fixed by the solidified molten resin. However, it is possible to create a gap between the valve body and the valve seat so that the outside air can be introduced into the cavity from the vent hole. By introducing outside air into the cavity and exerting the pressure on the molded product in the cavity, it is possible to reduce the mold release resistance of the molded product with respect to the mold. By continuing the relative movement of the molded product with respect to the mold, the concave undercut of the molded product is pulled away from the protrusion of the valve body without damaging the molded product, or the convex of the molded product is A shaped undercut can be extracted from the recess of the valve body.

(Characteristics of the invention according to claim 7)
The invention according to claim 7 comprises the components of the invention according to claim 6 and is connectable to a gas suction device disposed outside the mold in the gas vent hole of the mold. It is characterized by.

  According to the invention of claim 7, by operating a gas suction device connected to the gas vent hole of the mold, the molten resin is supplied from the inside of the cavity when being supplied into the cavity of the mold. The gas can be forcibly and more effectively discharged.

(Characteristics of the invention according to claim 8)
The invention according to claim 8 includes the components of the invention according to claim 6, and the vent hole of the mold can be connected to an air supply device arranged outside the mold. It is characterized by.

  According to the eighth aspect of the present invention, the air supply device connected to the vent hole of the mold is operated to forcibly supply the air into the cavity of the mold when the mold is opened. And more effectively.

  According to the present invention, it is possible to provide a valve that enables the introduction of outside air into the cavity through the vent hole of the mold when the mold is opened, and a mold including the valve.

  1 to 3, an example of an injection molding die attached to a plastic injection molding machine (not shown) and an example of a valve applied to the die are respectively denoted by reference numerals 1 and 3 as a whole. It is shown in

  The mold 1 includes a male mold 5 and a female mold 7 and has a cavity 9 defined by the male mold 5 and the female mold 7 when they are brought into contact with each other by a mold clamping operation of the injection molding machine. The male mold 5 is provided with an introduction path 13 for the molten resin 11 to be pressurized and filled into the cavity 9, and the female mold 7 is provided with a volatile gas emitted from the molten resin 11 introduced into the cavity 9 and the cavity 9. A vent hole 15 is provided that defines a passage for discharging the gas, such as existing air, out of the cavity 9.

  The gas vent holes 15 are opened to the outside of the cavity 9 and the mold 1 at both ends thereof. One end portion of the gas vent hole 15 opened to the cavity 9 is formed of a cylindrical concave portion 16 having a larger diameter than other portions other than the one end portion, and the valve 3 is disposed in the concave portion. The recess 16 in which the valve 3 is disposed is preferably located as far as possible from the introduction path 13 of the molten resin 11 so that the valve 3 is not immediately covered by the molten resin 11 supplied into the cavity 9. .

  The valve 3 opens and closes the gas vent hole 15. By opening and closing the gas vent hole 15, the cavity 9 and the gas vent hole 15 of the mold 1 are brought into a communication state (a state shown in FIG. 1) and a non-communication state (a state shown in FIG. 2). it can. When the cavity 9 and the gas vent hole 15 are in communication with each other, when the molten resin 11 is supplied into the cavity 9, the gas is discharged from the cavity 9 to the outside of the mold 1 through the gas vent hole 15. be able to. By discharging the gas, the molten resin 11 supplied into the cavity 9 can be more evenly distributed, whereby the filling degree of the molten resin 11 into the cavity 9 can be increased. For the gas discharge, instead of naturally discharging the gas, a gas suction device 17 such as a vacuum pump is disposed outside the mold 1 and connected to the gas vent hole 15. It can be forcibly performed by operating. Thereby, the gas can be discharged from the cavity 9 in a larger amount and in a shorter time. Further, when the cavity 9 and the gas vent hole 15 are not in communication with each other, leakage of the molten resin 11 supplied into the cavity 9 into the gas vent hole 15 is prevented.

  As shown in FIG. 2, after the molded product 19 (FIG. 3) is formed in the cavity 9 by solidification of the molten resin 11 filled in the cavity 9 of the mold 1, mold opening and molding by the injection molding machine are performed. The molded product 19 is taken out from the mold 1 through both operations of ejecting the product 19.

  As shown in FIG. 3, the mold opening is performed by translating the male mold 5 with respect to the female mold 7 so that the male mold 5 is separated from the molded product 19. Further, the protrusion of the molded product 19 is performed by advancing a plurality of ejector pins 20 arranged so as to penetrate the female mold 7 toward the cavity 9 and applying a pressing force to the molded product 19 in the cavity 9. . Since the cavity 9 is defined by the male mold 5 and the female mold 7, the space occupied by the molded product 19 after the mold opening cannot be accurately called a cavity. Is used. By the protrusion operation, the molded product 19 moves in the female mold 7 toward the male mold 5 and leaves the wall surface 21 of the female mold 7 that defines the cavity 9. As a result, a gap 23 is generated between the wall surface 21 of the female mold 7 and the molded product 19.

  By the way, the gap 23 generated by the protruding operation forms a sealed space under a negative pressure because the valve 3 is in a closed state. In the present invention, at this time, the valve 3 is opened to allow the cavity 9, that is, the gap 23 and the gas vent hole 15 to communicate with each other. It is possible to eliminate the state, apply external air pressure to the molded product 19, and make it easier to peel the molded product 19 from the female mold 7. Introducing outside air into the gap 23 is not natural, but an air supply device (not shown) such as a compressor is disposed outside the mold 1 and connected to the gas vent 15. However, it can be forcibly performed by operating the air supply device. Thereby, a larger amount of high-pressure air can be introduced into the gap 23.

  4 and 5 are enlarged sectional views, and FIGS. 6 and 7 are perspective views, and FIG. 8 is an exploded perspective view. And a valve body 27 held inside the valve seat 25 so as to be movable in the axial direction thereof, and a spring member 29.

  The valve seat 25 has an outer diameter and a height dimension that can be press-fitted into a recess 16 that forms one open end of the vent hole 15 of the mold 1 (female mold 7). The valve seat 25 is fixed to the female die 7 by press-fitting into the recess 16 so that one end surface (the upper end surface in FIG. 1) is flush with the wall surface 21 of the female die 7. The valve seat 25 has a seat surface 31 that defines the upper end surface thereof. The seat surface 31 is composed of a conical surface spreading toward the cavity 9 when the valve seat 25 is fixed to the female die 7.

  In addition, the valve body 27 is concentrically or coaxially within the valve seat 25 and is arranged to be movable in the axial direction of the valve seat 25 (three in the illustrated example) valve body portions 33, 35, 37. The central valve body portion 33 is composed of a rod-shaped body having a cylindrical shape as a whole, and the other two valve body portions 35 and 37 are each composed of a cylindrical body. The central valve body portion 33 is located on the axis of the valve seat 25, and the other two cylindrical valve body portions 35 and 37 are respectively surrounded by the central valve body portion 33 and the cylindrical valve body portion 35. Surrounding around.

  In these valve body portions 33, 35, and 37, the inner valve body portion 33 of the two adjacent valve body portions 33 and 35 can be seated on the outer valve body portion 35 and adjacent to each other. Of the two valve body portions 35, 37, the inner valve body portion 35 can be seated on the outer valve body portion 37, and the outermost valve body portion 37 can be seated on the valve seat 25. When the inner valve body portions 33 and 35 are respectively seated on the outer valve body portions 35 and 37 and the outermost valve body portion 37 is seated on the valve seat 25, these valve body portions 33 to 37 as a whole. It is located in the closed position which closes the valve seat 25 (refer FIG.2 and FIG.5). On the other hand, when the inner valve body portions 33 and 35 are separated from the outer valve body portions 35 and 37 and the outermost valve body portion 37 is separated from the valve seat 25, these valve body portions 33 to 37 are entirely formed. As shown in FIG. 1, FIG. 3, and FIG.

  Referring to FIGS. 4, 5, and 8, the central valve body portion 33 includes one end portion on which a seat surface 39 formed of a conical surface spreading toward the cavity 9 is formed, and a pair of notch surfaces facing each other. 41 is provided. The valve body portion 35 surrounding the valve body portion 33 has an inner and outer end portions provided with inner and outer seat surfaces 43 and 45 each having a conical surface spreading toward the cavity 9, and a pair of notches facing each other. And a side portion provided with a surface 47. Further, the outermost valve body portion 37 surrounding the valve body portion 35 has one end portion provided with inner and outer seating surfaces 49 and 51 each having a conical surface spreading toward the cavity 9 inside and outside thereof, and And side portions provided with a pair of opposed notch surfaces 53.

  Further, the central valve body portion 33 can move in the axial direction of the valve body portion 35 under the guiding action of the surrounding valve body portion 35, and the valve body portion 35 is the outermost valve body portion 37. The valve body portion 37 can be moved in the axial direction under the guiding action of the valve seat 25, and the outermost valve body portion 37 can be moved in the axial direction of the valve seat 25 under the guiding action of the valve seat 25. Accordingly, the valve body portions 33 to 37 can be moved in the axial direction of the valve seat 25 as a whole.

  The seat surface 39 of the valve body portion 33, the outer seat surface 45 of the valve body portion 35, and the outer seat surface 51 of the valve body portion 37 are respectively connected to the valve seat 25 in the axial direction. When moving in a direction away from the cavity 9, the inner seat surface 43 of the valve body portion 35, the inner seat surface 49 of the valve body portion 37, and the seat surface 31 of the valve seat 25 are brought into contact. By this contact, the valve body 33 is seated on the valve body 35, the valve body 35 is seated on the valve body 37, the valve body 37 is seated on the valve seat 25, and the valve bodies 33 to 37 are seated. Sits on the valve seat 25 as a whole.

  On the contrary, the seat surface 39 of the valve body portion 33, the outer seat surface 45 of the valve body portion 35, and the outer seat surface 51 of the valve body portion 37 are respectively connected to the valve seat portions 33 to 37. When moved toward the other of the 25 axial directions, that is, toward the cavity 9, the inner seat surface 43 of the valve body portion 35, the inner seat surface 49 of the valve body portion 37, and the seat surface 31 of the valve seat 25 The contact is released, and the valve body portions 33 to 37 leave the seat surface 31 of the valve seat 25 as a whole. At this time, between the seat surface 39 of the valve body portion 33 and the inner seat surface 43 of the valve body portion 35, the outer seat surface 45 of the valve body portion 35 and the inner seat surface 49 of the valve body portion 37. And gaps 55, 57, 59 are formed between the outer seating surface 51 of the valve body 37 and the seating surface 31 of the valve seat 25, respectively. The clearances 55 to 59 between these seating surfaces are the clearance 61 between the notch surface 41 of the valve body part 33 and the side part of the valve body part 35, the notch surface 47 of the valve body part 35, and the valve body part, respectively. 37 and the gap 65 between the notch surface 53 of the valve body 37 and the inner peripheral surface of the valve seat 25, and the cavity 9 and the gas vent hole 15 are passed through these gaps 55 to 65. Communicate with each other.

  An end portion 67 of a spring member 29 made of a coil spring surrounding the valve body portion 33 is fixed to the other end portion of the central valve body portion 33, and a C ring 69 partially surrounding the other end portion of the valve body portion 35. A C ring 71 is attached to the other end of the outermost valve body 37. Here, the end portion 67 of the spring member 29 can contact the other end surface of the adjacent valve body portion 35, and the C ring 69 can contact or engage the other end surface of the adjacent valve body portion 37, The C ring 71 can contact or engage with a stepped portion 73 provided on the inner peripheral surface of the valve seat 25.

  The spring member 29 is disposed in the valve seat 25 between the central valve body portion 33 and the female die 7 and is compressed in the axial direction of the valve seat 25. For this reason, the central valve body 33 always receives a spring force that is an elastic return force of the spring member 29 toward the cavity 9. A part of the spring force is transmitted to the adjacent valve body portion 35 through the end portion 67 of the spring member 29, and is transmitted to the outermost valve body portion 37 through the C ring 69. Thereby, these valve body parts 33-37 receive the biasing force which is a forward forcing force toward the cavity 9 as a whole. On the other hand, the C ring 71 surrounding the outermost valve body portion 37 can be brought into contact with or engaged with the stepped portion 73 of the valve seat 25, whereby the valve body portions 33 to 37 are closed. It is held in the valve seat 25 so as to be in the release position. In the example shown in FIGS. 1 to 5, the spring member 29 is arranged such that one end face facing the cavity 9 is aligned with the wall surface 21 of the female die 7 when the valve body portions 33 to 37 are in the closing release position. The attachment positions of the end 67 and the C rings 69 and 71 are set such that there is a step in the axial direction of the valve seat 25.

  On the other hand, when the molten resin 11 is filled in the cavity 9, the valve body portions 33 to 37 receive the pressing force of the molten resin 11 at one end face thereof, and the magnitude of the pressing force is the spring force of the spring member 29. When the size of the valve seat is exceeded, the valve seat 25 is retracted to the closed position. The magnitude of the spring force of the spring member 29 is determined in consideration of the type and viscosity of the molten resin 11. In the example shown in FIGS. 1 to 5, the retraction distance of the central valve body portion 33 is the largest, and then the retraction distance of the valve body portion 35 and the retraction distance of the valve body portion 37 are set to gradually decrease. .

  In the present invention, the central valve body 33 is provided with a protrusion 75 for forming an undercut 77 (see FIGS. 2 and 3) on the molded product 19 molded in the cavity 9. The protrusion 75 extends from the one end face of the valve body 33 on the axis thereof into the cavity 9 at the closing release position. The protrusion 75 has an outer shape that widens toward the cavity 9. More specifically, it consists of a truncated cone. Instead of this example, the protrusion 75 can be formed of, for example, a cylindrical body having a constriction.

  As shown in FIG. 3, the protrusion 75 embedded in the molded product 19 and defining the undercut 77 in the molded product 19 has a gap 23 between the female mold 7 and the molded product 19 by the protruding operation after the mold opening. When formed, it moves with it without slipping out of the molded product 19. Accordingly, the central valve body portion 33, the valve body portion 35, and the outermost valve body portion 37 that are in the closed position are sequentially entrained by the molded product 19 until the closed release position is reached. During this time, the gap 23 and the vent hole 15 communicate with each other, and outside air is introduced into the gap 23 through the vent hole 15. This is because the molten resin 11 filled in the cavity 9 enters the gaps 55 and 57 between the valve body parts 33 to 37 and the gap 59 between the valve body part 37 and the valve seat 25 and solidifies. Thus, even when the valve body portions 33 to 37 and the valve body portion 37 and the valve seat 25 are fixed to each other, it is possible to forcibly peel them off.

  The protrusion 75 is released from the molded product 19 due to the elastic deformation of the molded product 19 due to further movement of the molded product 19, and preferably, the molded product 19 is not cracked to damage the molded product 19 at this time. The size, shape, etc. are set so that the undercut 77 which is a recess remaining in the molded product 19 is not conspicuous.

  Instead of providing the protrusion 75, the central valve body portion 33 can be provided with a recess (not shown) opened at one end face thereof. For example, the depression may have a wall surface formed of a tapered conical surface toward the cavity 9. According to this, when the molten resin 11 with which the cavity 9 is filled also fills the dent and this is solidified, a convex undercut is formed. When the molded product is moved so that a gap is generated between the female die 7 and the molded product 19, the valve body 33, the valve body 35, and the valve body 37 are interposed through the convex undercut. Sequentially, a tensile force is exerted, and these are entrained by the molded product 19.

  An indentation or an engraving (not shown) for attaching a symbol to the surface of the molded product 19 can be formed on at least one of the one end faces of the valve body portions 33 to 37. According to this, when the molten resin 11 is filled in the cavity 9, the molten resin 11 is pressed against the indentation or inscription of the valve body parts 33 to 37, and the intaglio or inscription on the surface of the molded product 19 after mold release. The trace of remains. For example, it can be set to be an arbitrary symbol made up of a number, a serial number, a code, etc. representing a year or month, as an imprint or positive mark.

  As shown in FIGS. 9 and 10, when the valve body portions 33 to 37 are in the closing release position (position shown in FIG. 9), one end surface of the valve 3 includes the opening surface of the valve seat 25. When protruding from the wall surface 21 of the female mold 7 into the cavity 9 and in the closed position (position shown in FIG. 10), the one end surfaces of the valve body portions 33 to 37 are in a plane including the wall surface 21. can do. Therefore, in this example, the attachment position of the end portion 67 of the spring member 29 with respect to the valve body portion 33, the attachment position of the C ring 69 with respect to the valve body portion 35, and the attachment position of the C ring 71 with respect to the valve body portion 37 are described above. In the closing release position, the valve seat 25 is set at the same position in the axial direction so that the step does not exist.

  Further, as shown in FIGS. 11 and 2, the valve body 27 can be composed of a single valve body portion 81. This single valve body portion 81 is formed of the same valve body portion as the central valve body portion 33 in the valve shown in FIGS. The valve body portion 81 can abut on the seat surface 31 of the valve seat 25 at the seat surface 39, thereby closing the valve seat 25.

It is sectional drawing which shows the metal mold | die for injection shaping, and the valve | bulb applied to this, Comprising: It is sectional drawing in the state which started supply of the molten resin in the cavity of a metal mold | die. It is sectional drawing of the metal mold | die and valve | bulb in the state with which the molten resin was filled in the cavity. It is sectional drawing of the metal mold | die and valve | bulb in the state in which the molded article shape | molded in the cavity is performed. It is an expanded sectional view of a valve in the state where a valve element exists in a closure release position. It is an expanded sectional view of a valve in the state where a valve element exists in a closed position. It is an expansion perspective view of a valve in the state where a valve element exists in a closure release position. It is an expansion perspective view of a valve in the state where a valve element exists in a closed position. It is an exploded perspective view of a valve. It is an expanded sectional view of other examples of a valve in the state where a valve element exists in a closure release position. It is an expanded sectional view of other examples of a valve in the state where a valve element exists in a closed position. FIG. 10 is an enlarged cross-sectional view of still another example of the valve in a state where the valve body is in the closed release position. It is an expanded sectional view of the further another example of a valve in the state where a valve element exists in a closed position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 3 Valve 9 Cavity 11 Molten resin 15 Degassing hole 16 Recessed part 17 Gas suction device 19 Molded product 25 Valve seat 27 Valve body 29 Spring member 33 Valve body part 35 Valve body part 37 Valve body part

Claims (7)

A valve for opening and closing a vent hole provided in a mold for plastic injection molding and communicating with a cavity of the mold,
A valve seat disposed in the vent hole, and a valve body that is movable between a closed position that is held by the valve seat and closes the valve seat, and a closed release position that releases the valve seat. A biasing force is exerted on the valve body so that the valve body is in the closed release position, and the valve body receives a pressing force of a molten resin filled in a cavity of the mold from the closed release position. A spring member allowing movement to the closed position;
The valve body includes a protrusion or a recess for forming an undercut in a molded product molded in the cavity of the mold, and the undercut is configured so that the valve body is moved from the closed position when the mold is opened. It is possible to be taken to the molded product through the protrusion or depression to the closing release position, and to separate the valve body from the molded product without damaging the molded product. The
The valve body is composed of a plurality of concentrically arranged valve body portions, and among the valve body portions adjacent to each other, the inner valve body portion can be seated on the outer valve body portion, and the outermost valve body portion The portion can be seated on the valve seat,
Wherein the plurality of valve body, the valve characterized by engageable der Rukoto each other as the biasing force of the spring member is exerted on the valve body portion of the outer from the inner side of the valve body.   2. The valve according to claim 1, wherein the gas vent hole of the mold has a concave portion that is open to the cavity and in which the valve seat is disposed. 3.   3. The valve according to claim 1, wherein the protrusion of the valve body has an outer shape spreading toward the cavity, and the recess of the valve body has a tapered wall surface toward the cavity. 4. . At least one valve body portion has an inscription or an inscription for attaching a symbol to the surface of the molded article;
The valve according to any one of claims 1 to 3, wherein Providing a valve according to any one of claims 1-4,
A mold for plastic injection molding. The gas vent hole of the mold can be connected to a gas suction device arranged outside the mold.
The mold according to claim 5 , wherein The vent hole of the mold can be connected to an air supply device arranged outside the mold.
The mold according to claim 5 , wherein

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