JP2006192623A - Injection mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection mold capable of exhausting the gas, which is produced by the injection filling of a molten resin, to the outside without requiring maintenance work for removing the clogging of a gas exhaust passage even at a part where the gas is exhausted from a cavity space. <P>SOLUTION: The injection mold 1 is equipped with a fixed mold 3 and a movable mold 4 in order to form the cavity space 7 in which the molten resin is injected and filled. The recessed part 8 communicating with the cavity space 7 is formed to either one of the fixed mold 3 and the movable mold 4 and a gas passage 9 for allowing the gas produced by the injection filling of the molten resin to escape to the outside of the injection mold 1 from the cavity space 7 communicates with the bottom part 8a of the recessed part 8 and an on-off pin 19, which is movable between an opening position and a closing position, is provided to the gas passage 9 in order to open and close the gas passage 9 and moved to the closing position upon the reception of the pressure of the molten resin to constitute a part of the bottom part 8a at the closing position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mold used for injection molding, and more particularly to an injection mold that can release gas generated due to injection filling of molten resin from a cavity space to the outside of the mold.

  2. Description of the Related Art Conventionally, an injection mold having a fixed mold and a movable mold is known. The cavity space formed by the fixed mold and the movable mold is injected and filled with molten resin. When the resin is cooled and solidified, a molded product made of a cured resin formed into a shape that follows the cavity space can be obtained.

  Here, a gas such as a volatile gas component of the resin is generated in the cavity space during injection filling. This gas hinders the filling of the molten resin into the cavity space. In addition, when the gas is compressed to a high temperature, the molded product is burnt and burnt.

For this reason, an injection mold in which a porous material is used for a part of the fixed mold that forms the cavity space has been proposed (see, for example, Patent Document 1). In this injection mold, the gas in the cavity space can be discharged to the outside of the mold from the pores of the porous material.
Japanese Patent Laid-Open No. 10-034733 (page 2-6, FIG. 1)

  However, the pores of the porous material are easily clogged with molten resin. For this reason, in order to suppress the trouble caused by the gas, it is necessary to perform maintenance work of the fixed mold for removing the clogging of the holes. Along with this, the time and cost required for plastic molding increase.

  The present invention has been made in view of the above circumstances, and even in a portion where gas is discharged from the cavity space, the molten resin can be used without requiring maintenance work to remove clogging of the passage for discharging the gas. It is an object of the present invention to provide an injection mold that can discharge gas generated due to injection filling to the outside.

  In order to solve the above-described problems, an injection mold according to claim 1 is provided for injection molding including a fixed mold and a movable mold to form a cavity space into which molten resin is injected and filled. In the mold, either one of the fixed mold and the movable mold is formed with a recess communicating with the cavity space, and the bottom of the recess is caused by injection filling of the molten resin. A gas passage for allowing the generated gas to escape from the cavity space to the outside of the injection mold is communicated, and the gas passage has an open position and a closed position for opening and closing the gas passage. A movable opening and closing pin is provided, and the opening and closing pin receives the pressure of the molten resin and moves to the closed position, and forms a part of the bottom at the closed position.

  The injection mold according to claim 2 is the injection mold according to claim 1, wherein a conical fitting portion is provided at one end of the opening and closing pin, and the fitting is provided at the bottom portion. A taper-shaped receiving portion for receiving a joint portion is formed, and the opening / closing pin is fitted to the receiving portion at the closed position.

  The injection mold according to claim 3 is the injection mold according to claim 1 or 2, wherein the open / close pin releases the cured resin from the injection mold. It functions as an extrusion pin of an ejector ejecting mechanism.

  The injection mold according to claim 4 is the injection mold according to claim 3, wherein the open / close pin is moved to the open position by an extrusion operation to maintain the open position. It is characterized by that.

  According to the first aspect of the present invention, the gas in the cavity space is exhausted from the gas passage leading to the recess. The gas passage is opened and closed by an opening and closing pin that moves to the closed position under the pressure of the molten resin to be injected and filled. Since the open / close pin constitutes the bottom of the recess when in the closed position, the molten resin filled in the recess is prevented from entering the gas passage. For this reason, gas can be discharged | emitted from cavity space, without requiring the maintenance operation | work which removes clogging of a gas channel, and the malfunction which gas causes can be suppressed.

  According to the second aspect of the present invention, since the fitting portion has a conical shape and the receiving portion is formed in a tapered shape, the opening position can be reduced with a small movement distance from the closing position to the opening position of the opening / closing pin. The gap between the fitting portion and the receiving portion can be set to a desired size.

  According to the third aspect of the present invention, the open / close pin also serves as the push pin of the ejector ejecting mechanism. In general, since the extrusion pin is used for an injection mold, it is not necessary to provide a new part for opening and closing the gas passage.

  According to the fourth aspect of the present invention, since the opening / closing pin returns to the open position by the extrusion operation, gas can be discharged from the cavity space even when injection molding is continuously performed.

  Embodiments of an injection mold according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing an injection molding machine 2 to which an injection mold 1 according to the present invention is applied.

  The injection mold 1 includes a fixed mold 3 and a movable mold 4 that face each other. The movable mold 4 is located below the fixed mold 3 and includes a core mold 5 and a core insert 6 disposed inside the core mold 5. The core insert 6 forms a cavity space 7 in cooperation with the opposing fixed mold 3. The core insert 6 is formed with a recess 8 that communicates with the cavity space 7. A gas passage 9 communicates with the bottom 8 a of the recess 8.

  The gas passage 9 is formed through the core mold 5 and the core insert 6 and extends from the recess 8 toward the outside of the movable mold 4. A receiving portion 10 is formed in the gas passage 9. The receiving portion 10 is provided at the bottom portion 8 a of the recess 8 and has a tapered shape with a diameter gradually increasing toward the recess 8.

  The fixed mold 3 is attached to the fixed side mounting plate 11. The fixed mold 3 and the fixed-side mounting plate 11 are formed with sprues 12 that communicate with the cavity space 7.

  The movable mold 4 is attached to a plurality of spacer blocks 13, and each spacer block 13 is attached to a movable side attachment plate 14. The movable mold 4 and the movable side mounting plate 14 are provided at intervals from each other by the spacer blocks 13. The movable side mounting plate 14 is provided in parallel with each other so as to face the fixed side mounting plate 11, and is provided so as to be movable in the vertical direction while maintaining this opposing and parallel relationship.

  An ejector plate 15 is disposed between the movable mold 4 and the movable side mounting plate 14. The ejector plate 15 is provided so as to be movable between the movable mold 4 and the movable side mounting plate 14 in the vertical direction. The ejector plate 15 is configured by overlapping two upper and lower plates 15a and 15b.

  A recess 16 is formed in the upper plate 15a. The recess 16 is located in the extending direction of the gas passage 9 and on the surface facing the lower plate 15b of the upper plate 15a. The recess 16 forms a space 17 in cooperation with the lower plate 15b. A through hole 18 communicates with the space 17. The through hole 18 has a central axis equal to the gas passage 9 and is provided so as to penetrate the upper plate 15a.

  An opening / closing pin 19 is disposed in the gas passage 9. The open / close pin 19 includes an elongated cylindrical body portion 20, a fitting portion 21 provided at the upper end of the body portion 20, and a flange portion 22 provided at the lower end of the body portion 20. The body portion 20 is formed to have an outer diameter smaller than the inner diameter of the gas passage 9. The fitting portion 21 has a conical shape whose diameter gradually increases toward the upper end, and can be fitted to the receiving portion 10 of the recess 8. The flange portion 22 is formed in such a size that it can exist in the space 17 of the ejector plate 15 and cannot pass through the through hole 18.

  The body 20 of the open / close pin 19 is slidably held by the through hole 18 and is inserted into the gas passage 9. The opening / closing pin 19 is arranged so that the fitting portion 21 is located in the recess 8 and the flange portion 22 is located in the space 17. The movement range of the open / close pin 19 is restricted by the movement range of the flange portion 22 in the space 17. The flange portion 22 is movable inward of the space 17 between a position in contact with the lower plate 15b and a position in contact with the upper plate 15a. When the opening / closing pin 19 is in the lowest position, the fitting portion 21 is fitted into the receiving portion 10 of the recess 8 to close the gas passage 9. The open / close pin 19 opens the gas passage 9 when the fitting portion 21 is at a position spaced from the receiving portion 10. The open / close pin 19 is biased upward by a spring (not shown) provided in the space 17. The opening / closing pin 19 is in the open position before the molten resin R is filled into the cavity space 7. The urging means may be any means that urges the opening / closing pin 19 upward, and may be, for example, an air spring configured by increasing the pressure of air in the space 17.

  In the present embodiment, the flange portion 22 is provided with a screw portion 22a as shown in FIG. The flange portion 22 can be fastened to the lower end of the trunk portion 20 via the screw portion 22a. For this reason, the open / close pin 19 inserts the barrel 20 having the fitting portion 21 from the recess 8 of the movable mold 4 into the gas passage 9 and the through hole 18, and from the recess 16 of the upper plate 15 a to the lower end of the barrel 20. By attaching the flange portion 22 to the gas passage 9, the gas passage 9 and the through hole 18 can be inserted.

  Next, the operation of the injection mold 1 during injection filling will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view showing the operation at the time of injection filling of the injection mold 1 according to the present invention in order (a) to (c).

  Molten resin R is injected from the sprue 12 into the cavity space 7 (see FIG. 3A). At this time, gas such as a volatile component and a gas component of the resin R is generated from the molten resin R in the cavity space 7. In addition, air exists in the cavity space 7. The open / close pin is in the open position, and the gas and air pass between the fitting portion 21 and the receiving portion 10 and are discharged to the outside of the injection mold 1 through the gas passage 9 (FIG. 3 ( a) See arrow A).

  When the molten resin R is further injected and the molten resin R reaches the upper end of the fitting portion 21, the fitting portion 21 is pushed by the molten resin R, and the open / close pin 19 is biased by a spring (not shown). And move toward the closed position (see arrow B in FIG. 3B).

  When the molten resin R reaches the bottom 8a of the recess 8, the open / close pin 19 reaches the closed position (see FIG. 3C), and the gas passage 9 is closed. The molten resin R is filled in the cavity space 7 and the recess 8. At this time, the molten resin R is prevented from entering the gas passage 9 by the opening / closing pin 19 in the closed position. When the filled molten resin R is cooled and solidified, a molded product P made of a cured resin formed into a shape following the cavity space 7 and the recess 8 is formed.

  Next, the operation of the injection molding machine 2 when the molded product P is released from the injection mold 1 will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view showing the mold release operation of the injection molding machine 2 in order (a) to (c).

  The movable side mounting plate 14 is moved downward (see arrow C in FIG. 4A).

  Thereafter, the ejector plate 15 is moved upward (see arrow D in FIG. 4B). Along with this movement, the collar portion 22 is pushed by the lower plate 15b, and the open / close pin 19 moves to the open position (see arrow E in FIG. 4B). The molded product P is pushed out of the cavity space 7 by the open / close pin 19 (see arrow F in FIG. 4B). Therefore, the ejector plate 15 and the opening / closing pin 19 function as an ejector pushing mechanism for releasing the molded product P from the injection mold 1.

  The ejector plate 15 is moved downward (see arrow G in FIG. 4C), and the movable side mounting plate 14 is moved upward (see arrow H in FIG. 4C). The opening / closing pin 19 is in the open position regardless of the movement of the ejector plate 15 by the biasing of a spring (not shown). For this reason, the gas can be discharged from the cavity space 7 even if injection molding is continuously performed.

According to this injection mold 1, the following effects can be obtained.
(1) Since the open / close pin 19 pushed by the molten resin R closes the gas passage 9 to prevent the molten resin R from entering the gas passage 9, the filling of the molten resin R into the cavity space 7 is performed. The clogging of the gas passage 9 due to is prevented. For this reason, gas can be discharged | emitted from the cavity space 7 without requiring the maintenance operation | work of the metal mold | die for removing clogging, and the time and expense which plastic molding requires can be suppressed.
(2) Since the opening / closing pin 19 has a structure for opening and closing the gas passage 9 according to the interval between the tapered receiving portion 10 and the conical fitting portion 21, the opening and closing pin 19 can be moved from the recessed portion 8 to the gas passage 9 with a small movement range. It is possible to secure a gas exhaust passage.
(3) The open / close pin 19 also serves as an extrusion pin for releasing the molded product P. Since the extrusion pin is generally applied to an injection molding machine, it is not necessary to provide a new part in order to prevent the molten resin R from entering the gas passage 9.
(4) The open / close pin 19 moves to the closed position as the molten resin R is filled, and also moves to the open position as the molded product P is released. It can be discharged from the cavity space 7.
(5) The opening / closing pin 19 closes the gas passage 9 by the fitting portion 21 being pushed by the molten resin R and fitting into the receiving portion 10 provided on the bottom portion 8a of the recess 8, so that the molten resin Gas can be discharged from the cavity space 7 until R reaches the bottom 8a. Since the cavity space 7 is substantially filled with the molten resin R when the molten resin R reaches the bottom 8a of the recess 8, the gas can be discharged until just before the cavity space 7 and the recess 8 are filled. It is possible to more effectively suppress the problems caused by.

  In the above-described embodiment, the concave portion 8, the gas passage 9 leading to the concave portion 8, and the open / close pin 19 for opening and closing the concave portion 8 are provided in the movable mold 4, but may be provided in the fixed mold 3. However, the present invention is not limited to the examples.

  If the gas passage 9 and the open / close pin 19 are provided, the gas can be discharged from the cavity space 7 and the molten resin R can be prevented from entering the gas passage 9. May not be provided.

  Furthermore, since it is sufficient that the gas can be discharged from the cavity space 7 and the molten resin R can be prevented from entering the gas passage 9, the opening / closing pin 19 does not have to serve as an extrusion pin.

1 is a cross-sectional view schematically showing an injection molding machine to which an injection mold according to the present invention is applied. It is typical sectional drawing for demonstrating the structure of an opening-and-closing pin. It is typical sectional drawing for demonstrating operation | movement of the opening / closing pin at the time of resin injection filling, (a) shows the state by which injection filling of molten resin was started, (b) is an opening / closing pin by molten resin. (C) has shown the state which injection filling of the molten resin was completed. It is typical sectional drawing for demonstrating operation | movement of the injection molding machine at the time of mold release of a molded article, and its opening-and-closing pin, Comprising: (a) shows the state by which the movable side mounting plate was moved below, (b ) Shows a state in which the ejector plate has been moved upward, and (c) shows a state in which the release operation has been completed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection mold 3 Fixed mold 4 Movable mold 7 Cavity space 8 Recess 9 Gas passage 10 Receiving part 19 Opening / closing pin 21 Fitting part R Molten resin

Claims (4)

In order to form a cavity space into which molten resin is injected and filled, an injection mold having a fixed mold and a movable mold,
A recess communicating with the cavity space is formed in one of the fixed mold and the movable mold, and a gas generated due to injection filling of the molten resin is formed in the bottom of the recess. A gas passage is formed to escape from the space to the outside of the injection mold. The gas passage has an opening / closing pin that can move between an open position and a closed position to open and close the gas passage. An injection mold, wherein the opening / closing pin is moved to the closed position under the pressure of the molten resin and constitutes a part of the bottom at the closed position.   A conical fitting portion is provided at one end of the opening and closing pin, a tapered receiving portion for receiving the fitting portion is formed at the bottom portion, and the opening and closing pin is in the closed position and the fitting portion is in the closed position. The injection mold according to claim 1, wherein the injection mold is fitted to the receiving portion.   The injection mold according to claim 1, wherein the open / close pin functions as an extrusion pin of an ejector ejecting mechanism that releases the cured resin from the injection mold. The injection mold according to claim 3, wherein the open / close pin is moved to the open position by an extrusion operation to maintain the open position.

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