JP2009274216A - Injection mould and injection molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out injection molding by simply adjusting the forming position of a direct sprue gate on the basis of a weld without manufacturing another fixed mold. <P>SOLUTION: A sprue bush 7 with the direct sprue gate 7a which is fixed attachably/detachably to the fixed mold 2 of an injection molding mold 1 and directly communicates with a cavity surface formed is composed of a plinth part 71 closely in contact with the nozzle of an injection molding machine, an engagement part 72 which is formed integrally with the plinth part 71 and can be engaged with the fixed mold 2, and a product part 73 which is formed integrally with the engagement part 72 and can be engaged with the fixed mold 2. The product part 73 of the sprue bush 7, to make its center be positioned on an imaginary line binding the centers of a plurality of direct sprue gates anticipated from the symmetrical shape of a molding, is formed to have an elliptic cross section which can open the direct sprue gate in a tip surface, and direct sprue gate 7a opening in the tip surface by being centered in a point on the imaginary line is formed in the sprue bush 7 to penetrate it. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection mold and an injection molding method.

  In general, an injection mold includes a fixed side mold and a movable side mold that can be clamped and opened with respect to the fixed side mold, and is formed into a molded product shape by the clamped fixed side mold and the movable side mold. Corresponding cavities are formed. A molded product corresponding to the cavity shape can be formed by injecting and filling molten resin into the cavity and solidifying it.

  By the way, when molding a molded product by injection molding, the molten resin is divided, such as the merging of the flow from two gates and the merging of the flow generated by the convex part of the mold to form the window of the molded product. After that, the resin joint when the molten resin joins from two directions is called a weld. When the resin temperature is low, the fusion of two or more molten resins is hindered, and the appearance of the line pattern is strong and weak coming out. If such a weld appears in a molded product, it becomes a defect in appearance and greatly affects the strength of the molded product, so it is preferably removed.

  For this reason, for welds, welds can be made as small as possible by adjusting the molding conditions such as increasing the resin temperature, raising the mold temperature, etc. Although measures are taken to devise the position and number of gates to move the position where the weld comes out to an inconspicuous position or a position that does not affect the strength, it cannot often be removed from the point of the product shape.

  On the other hand, when deciding the position of the gate of the molded product, the designer should use the flow length (L / T) determined by the thickness T of the molded product and the length L of the resin flow path as appropriate based on experience and intuition. The gate position was decided where it seemed. The determination of the gate position and the like based on the designer's experience and intuition has a large difference between individuals, and there is a limit in accuracy when the shape of the molded product is complicated.

In response to such a problem, an attempt to determine the gate position by flow analysis of molten resin has been proposed (see, for example, Patent Document 1).
JP-A-7-137109

  However, the gate position determined by the flow analysis is based on the given molding conditions, and the molding conditions are different between the prototype and the actual machine in the production line. Not exclusively. For example, when a molten resin is injected and filled through a sprue gate to form a molded product, the fixed side mold is manufactured so that the sprue gate opens at the expected position, and the sprue bushing is formed on the manufactured fixed side mold. The sprue gate is adjusted by adjusting the position of the sprue gate while confirming the weld by actually performing injection molding, and finally the optimum sprue gate is determined. Therefore, every time the sprue gate is changed, it is necessary to manufacture a fixed mold in which the position where the sprue bushing is mounted is manufactured, which increases costs and requires a lot of time until product development. It was.

  The present invention has been made in view of such a problem, and can perform injection molding by simply adjusting the formation position of the direct sprue gate based on the weld without newly manufacturing a fixed mold. A molding die and an injection molding method are provided.

  The injection mold of the present invention comprises a fixed side mold provided with a fixed side mold plate and a movable side mold provided with a movable side mold plate that can be opened with respect to the fixed side mold plate. A cavity corresponding to the molded product is formed by the movable side mold plate and the fixed side mold plate, and the sprue bush having the direct sprue gate is detachably fixed to the fixed side mold. In the injection mold, the sprue bushing is formed integrally with the pedestal portion that is in close contact with the nozzle of the injection molding machine, the fitting portion that can be fitted to the fixed side mold, and the fitting portion. And a product part that can be fitted to a fixed mold, and the product part is directly positioned so that its center is located on an imaginary line that connects the centers of a plurality of direct sprue gates expected from the shape of the molded product. Open the sprue gate at the tip It is formed on the ability minimal cross-sectional shape, and is characterized in that the direct sprue gate that opens to front end surface around a given point of a virtual line is formed through the sprue bushing.

  According to the present invention, the sprue bush is formed with a direct sprue gate that opens to the tip surface around an arbitrary point on an imaginary line that connects the centers of a plurality of direct sprue gates expected from the shape of the molded product. Then, this sprue bushing is fixed to the fixed mold and injection molded, and the weld of the molded product is examined. If necessary, change the direct sprue gate. In other words, if it is necessary to adjust the position of the direct sprue gate due to the weld, the direct sprue gate that opens to the tip surface around the other imaginary line in the direction to cancel the weld generated by the previous injection molding is used. A new sprue bushing may be formed, and the new sprue bushing may be fixed to the stationary mold instead of the previous sprue bushing and injection molded.

  As a result, by forming an arbitrary direct sprue gate of the plurality of direct sprue gates expected from the shape of the molded product on the sprue bushing, the direct sprue gate based on the examination results of the weld of the molded product by the direct sprue gate It becomes possible to easily change to a new sprue bush with the gate adjusted, and the weld of the molded product can be easily adjusted. Therefore, there is no need to newly manufacture a fixed mold every time the direct sprue gate is changed, and the cost can be greatly reduced and the period required for product development can be greatly shortened.

  In the present invention, the product part preferably has an oval cross section. In other words, when the shape of the molded product is a left-right symmetric shape or a substantially left-right symmetric shape, it is not necessary to adjust the formation position of the direct sprue gate in the left-right direction, so the expected virtual line extends in the up-down direction. The product portion has an oval cross section so that the direct sprue gate can be opened at the tip surface so that the center is located from the upper limit to the lower limit of the line segment on the axis of symmetry.

  The injection molding method of the present invention is a molding method in which injection molding is performed using the injection mold according to claim 1 or 2, wherein a direct sprue gate that opens at a tip surface around one point on the imaginary line passes through the sprue bush. After the sprue bushing is fixed to the stationary mold and injection molded, if necessary, a direct sprue gate that opens to the front end surface around the other point on the imaginary line is passed through the sprue bushing. The new sprue bushing is fixed to a fixed side mold and injection molded.

  According to the present invention, the sprue bush is formed with a direct sprue gate that opens at the tip surface around a point that is determined to be most appropriate on the imaginary line that connects the centers of a plurality of direct sprue gates expected from the shape of the molded product. After that, the sprue bushing is fixed to the fixed mold and injection molded. Then, consider the weld of the injection-molded molded product, and when it is necessary to adjust the position of the direct sprue gate based on the examination result, other points on the virtual line in the direction to cancel the weld generated by the previous injection molding A direct sprue gate that opens to the front end surface as a center is newly formed on the sprue bush. Next, a new sprue bush in which the adjusted direct sprue gate is formed is fixed to a fixed mold instead of the previous sprue bush, and injection molding is performed.

  As a result, it is possible to easily manufacture and replace the sprue bush with the position of the direct sprue gate adjusted based on the results of the weld examination of the molded product, and newly manufacture a fixed mold to match the direct sprue gate. Thus, the cost can be greatly reduced and the period required for product development can be greatly shortened.

  As described above, according to the present invention, it is possible to easily adjust the formation position of the direct sprue gate based on the weld and perform injection molding without newly manufacturing a fixed mold.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an injection mold 1 of the present invention.

  The injection mold 1 includes a fixed-side mold 2 and a movable-side mold 3 that moves in the left-right direction with respect to the fixed-side mold 2 to perform mold clamping and mold opening. On the other hand, when the movable mold 3 is clamped, a cavity corresponding to the molded product 100 is formed on the mating surface of both.

  Here, the molded product 100 has a left-right symmetric shape with respect to the axis of symmetry in the left-right direction (the direction orthogonal to the paper surface in FIG. 1).

  The fixed-side mold 2 includes a fixed-side mounting plate 4 and a fixed-side mold plate 5 that is integrally connected to the fixed-side mounting plate 4. The fixed-side mounting plate 4 is provided with a locating ring 6. A sprue bush 7 is provided over the fixed side mounting plate 4 and the fixed side mold plate 5, and a guide pin 8 is provided on the fixed side mold plate 5.

  In this case, the fixed-side template 5 is formed in a shape corresponding to the cross-sectional shapes of the fitting portion 72 and the product portion 73 of the sprue bush 7 as will be described later. The product part 73 can be fitted. When the sprue bush 7 is attached to the fixed side mold 2, the tip of the sprue gate that communicates directly with the cavity surface, that is, the direct sprue gate 7a opens into the cavity.

  Note that the center of the opening of the tip of the direct sprue gate 7a of the sprue bush 7 is located on the axis of symmetry corresponding to the shape 100 of the molded product 100 being bilaterally symmetric.

  The movable die 3 is integrally connected to a movable plate 9 that is connected to an actuator (not shown), a receiving plate 11 that is integrally connected to the movable plate 9 via a spacer block 10, and a receiving plate 11. The movable side mold plate 12 and the projecting plate 14 provided slidably with respect to the movable side mounting plate 9 and provided with the projecting pins 13 are provided. A guide hole 12a is formed so as to face the guide pin 8 provided in 5, and a guide bush 15 having an inner diameter corresponding to the diameter of the guide pin 8 is disposed in the guide hole 12a. 8 is inserted into the guide bush 15 when the mold is clamped, and is relatively slid along the guide bush 15 when the mold is opened.

  On the other hand, the protruding pin 13 provided on the protruding plate 14 extends through the receiving plate 11 to the movable side mold plate 12 and is set so that the tip thereof faces the cavity of the movable side mold plate 12. Yes. Further, the eject rod 16 provided on the protruding plate 14 is fitted in a fitting hole 9a formed in the movable mounting plate 9, and is set so as to face an actuator (not shown) when the mold is opened.

  2 and 3, the sprue bush 7 is formed integrally with the pedestal portion 71 and the pedestal portion 71 that are in close contact with the nozzle of an injection molding machine (not shown). A fitting portion 72 that can be fitted to the plate 5, and a product portion 73 that is formed integrally with the fitting portion 72 and can be fitted to the fixed-side mold plate 5 of the fixed-side mold 2. 73 is formed in a minimum cross-sectional shape that allows the direct sprue gate 7a to open to the front end surface so that the center is located on a virtual line connecting the centers of the plurality of direct sprue gates 7a expected from the shape of the molded product 100. ing. The sprue bush 7 has a direct sprue gate 7 a that opens with a point on the imaginary line of the tip surface of the product portion 73 as the center and has a drop gradient gradually increasing from the pedestal portion 71 toward the product portion 73. The pedestal portion 71, the fitting portion 72 and the product portion 73 are formed so as to penetrate therethrough.

  In the present embodiment, the product portion 73 of the sprue bush 7 is formed in an oval cross-sectionally symmetrical shape. That is, since the molded product 100 has a left-right symmetrical shape, it is not necessary to adjust the position of the direct sprue gate 7a in the left-right direction of the product portion 73 (the direction orthogonal to the paper surface in FIG. 1), An imaginary line that connects the centers of the direct sprue gates is a line segment on the axis of symmetry extending in the vertical direction, and an oval cross-sectional shape that allows the direct sprue gate 7a to open to the tip surface so that the center is located from the upper limit to the lower limit Is formed.

  Next, the operation of the injection mold 1 configured as described above will be described.

  First, the direct sprue that opens at the tip surface so that the center is located at the most suitable point on the imaginary line connecting the centers of a plurality of direct sprue gates expected from the shape of the molded product 100 to the sprue bush 7. It is formed through the gate 7a. Then, the sprue bush 7 is fixed to the fixed mold 2 and, as shown in FIG. 1, with the movable mold 3 clamped to the fixed mold 2, the molten resin is injected into the cavity and solidified. Then, the movable side mold 3 is opened. That is, when the movable side mounting plate 9 is moved in a direction away from the fixed side mold 2 via an actuator (not shown), the receiving plate 11 connected to the movable side mounting plate 9 and the movable side mold plate connected to the receiving plate 11 12 follows and moves. As a result, the molded product 100 is released from the fixed-side mold plate 5 while being held by the movable mold plate 12, and the sprue integrated with the molded product 100 is detached from the sprue bush 7 (see FIG. 4).

  Next, when an actuator (not shown) is operated and the eject rod 16 is pushed out through the fitting hole 9 a of the movable side mounting plate 9, the molded product 100 having the sprue is separated from the movable side template 12 via the protruding pins 13. (See FIG. 5).

  On the other hand, when the movable side mold 3 is clamped, the movable side mounting plate 9 may be retracted so as to approach the fixed side mold 2, contrary to the above. That is, the receiving plate 11 and the movable mold plate 12 may be moved in conjunction with the movable mounting plate 9 by pulling the movable mounting plate 9. When the movable side mold plate 12 comes into contact with the fixed side mold plate 5, the movement of the movable side mold plate 12 is prevented and the mold is clamped (see FIG. 1).

  By the way, regarding the molded product 100 made of the sprue bush 7 in which the direct sprue gate 7a described above is formed, the size, thickness and thickness of the weld, the generated position, and the like are examined. Then, as a result of the examination, if it is determined that the weld needs to be adjusted, a sprue bush in which a new direct sprue gate 7a is formed at a position where the weld generated in the molded product 100 by the previous injection molding is canceled. 7 is made. For example, the direct sprue gate 7a ′ whose center is located at a position spaced apart from the front opening position of the direct sprue gate 7a of the previous sprue bush 7 by a set interval above and below the predicted imaginary line is opened at the front end surface. A new sprue bushing 7 'is formed by penetrating through the sprue bushing. Then, a new sprue bush 7 'may be attached to the stationary mold 2 in place of the previous sprue bush 7 and injection molded again. Then, the molding result by the new sprue bush 7 'is examined again. Such adjustment work is performed until an optimum molding result is obtained.

  In this case, as described above, since the direct sprue gate 7a ′ of the sprue bush 7 ′ is opened at the front end surface on the line segment extending vertically, the direct sprue gate 7a ′ is inverted by 180 degrees and attached to the fixed mold 2. It is possible to adjust the direct sprue gate 7a ′ on the upper and lower one side and the other side.

  As described above, the weld generated in the molded product 100 can be dealt with by manufacturing a sprue bush with a direct sprue gate adjusted, as compared to a case where a fixed side mold including a fixed side mold plate is newly manufactured. The cost can be greatly reduced and the time required for product development can be greatly shortened.

  In the above-described embodiment, the sprue bush 7 having the specific direct sprue gate 7a is manufactured and injection-molded, and a new direct sprue gate 7a ′ is formed corresponding to the weld generated in the molded product 100. Although the case where the sprue bush 7 ′ is manufactured has been described, a plurality of sprue bushes 7 in which direct sprue gates whose centers open to the front end surface at different positions on the expected line can be prepared in advance.

It is sectional drawing which shows the clamping state of the injection mold of this invention. It is a perspective view which shows the sprue bush of the injection mold of FIG. FIG. 3 is a front view and a side view showing the sprue bush of FIG. It is sectional drawing explaining the mold opening process of the injection mold of FIG. It is sectional drawing explaining the protrusion process of the injection mold of FIG. It is the front view and side view which show the other sprue bush which formed the different direct sprue gate partly fractured. It is sectional drawing which shows the clamping state of the injection mold which attached the sprue bush of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection molding die 2 Fixed side type | mold 3 Movable side type | mold 5 Fixed side type | mold plate 7,7 'Sprue bush 7a, 7a' Direct sprue gate 71 Base part 72 Fitting part 73 Product part 12 Movable side type | mold template 100 Molded article

Claims (3)

  A movable side mold plate comprising a fixed side mold having a fixed side mold plate and a movable side mold having a movable side mold plate that can be opened with respect to the fixed side mold plate; In the injection mold in which the cavity corresponding to the molded product is formed by the fixed side mold plate of the fixed side mold, and the sprue bush having the direct sprue gate is detachably fixed to the fixed side mold, the sprue bush Is formed in one piece with the pedestal, which is in close contact with the nozzle of the injection molding machine, and can be fitted into the fixed-side mold, and is formed integrally with the fitting, and is fitted into the fixed-side mold. The product part can be opened to the front end surface so that the center is located on an imaginary line connecting the centers of a plurality of direct sprue gates expected from the shape of the molded product. Minimal cross-sectional shape Made is, injection mold, characterized in that the direct sprue gate that opens to front end surface around a given point of a virtual line is formed through the sprue bushing.   2. The injection mold according to claim 1, wherein the product part has an oval cross section.   3. A molding method for injection molding using the injection mold according to claim 1 or 2, wherein a direct sprue gate that opens at a front end surface around one point on the imaginary line is formed through the sprue bush, and the sprue bush After fixing to the fixed mold and injection molding, if necessary, a new direct sprue gate that opens to the tip surface around the other point on the imaginary line is formed through the sprue bush. An injection molding method, wherein the bushing is fixed to a fixed mold and injection molding is performed.

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