JPH09155927A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deflection of the mold due to the injection pressure or mold clamping pressure by disposing the gate for generating pressure peak and spacer formed with an ejector space in superposition in the pressure operating direction. SOLUTION: The respective gates 10 each for generating pressure peak and spacer 5 forming an ejector space 13 are arranged in layers in the pressure operating direction. Even if large downward pressure is operated from each gate 10 and a movable side mold plate 3 and a support plate 4 are pressed in the same direction after the molten material of a resin and the like arrives at each gate 10 at the time of injecting, the spacer 5 is disposed at the lower side of the plate 4. Since it is not a space, it makes it possible to prevent the large deflection from being generated toward the circumferential direction at the plate 4. As a result, the deflection is scarcely generated at the mold toward the same direction. Accordingly, the flash of the thickness necessary for the intrinsic removing operation after the molding scarcely occurs to make it possible to improve the dimensional accuracy of the product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die used for injection molding.

[0002]

2. Description of the Related Art As shown in FIGS. 7 to 9, an injection mold has conventionally been provided with a plurality of ejector pins 51 for ejecting a molded product (not shown) when the mold is opened. An ejector plate 52 for actuating the pin 51 is arranged in the ejector space 55 between the movable side mounting plate 53 and the receiving plate 54. The ejector space 55 includes the movable-side mounting plate 53 and the receiving plate 5.
It is provided between both blocks 56 and 57 by interposing a pair of spacer blocks 56 and 57 between the four blocks, and as shown in FIG. In a direction (vertical direction in the figure) orthogonal to the left-right direction in the figure, the ejector space 55 is opened to the outside with the size of the interval w as it is between the blocks 56 and 57.

That is, as seen in a plan view as shown in FIG. 9, the ejector space 55 is set to have a relatively large occupied area, and thus the sprue 58, runner 59, gate 60 and cavity 61 for the ejector space 55 are arranged. Looking at the planar arrangement relationship, almost all of these are vertically overlapped with the ejector space 55. Therefore, the space formed by the ejector space 55 is below the sprue 58, the runner 59, the gate 60 and the cavity 61. (Cavity) is present.

On the other hand, the injection pressure (also referred to as filling pressure) or the mold clamping pressure (also referred to as holding pressure) applied by the mold may reach a value of 500 kgf / cm ² or more. When acting on the mold, since the space by the ejector space 55 exists below the sprue 58, the runner 59, the gate 60, and the cavity 61, the movable side mold plate 62 and the receiving plate 54 are bent in the same direction. May occur.

At present, in order to suppress this bending, a measure is taken in which a support pillar (not shown) is arranged in the ejector space 55 as a support. Even if such a measure is taken, the movable side mold plate is also used. A gap (not shown) having a size of 30 μm or more may occur on the parting surface 64 between the 62 and the fixed-side mold plate 63.

When a gap having a size of 30 μm or more is generated on the parting surface 64, a molten material such as resin flows into this gap, so that a thin film (also called a burr) made of the molten material is formed on the parting surface 64. It When the molten material flows into the gap generated on the parting surface 64, the injection pressure or the mold clamping pressure (or its reaction force, the same applies hereinafter).
Since the pressure receiving area for receiving the pressure increases and the pressure per unit area decreases, the gap between the parting surfaces 64 becomes large and burrs grow. Therefore, it is necessary to remove the burr after the molding, and this hinders the improvement of productivity. Further, when the pressure per unit area decreases, the internal pressure of the cavity 61 also decreases, so that the strength of the product decreases, which causes the improvement of the product strength to be hindered.

[0007]

In view of the above points, the present invention can effectively suppress the bending of the mold due to the injection pressure or the mold clamping pressure, and prevent a gap from being generated on the parting surface. It is an object of the present invention to provide an injection molding die that can be effectively suppressed and thus can improve productivity and product strength.

[0008]

In order to achieve the above object, the injection molding die according to claim 1 of the present invention has a pressure so that bending of the die due to injection pressure or mold clamping pressure can be suppressed. The gate where the peak occurs and the spacer with the ejector space formed are arranged to overlap in the pressure acting direction. An injection molding die according to claim 2 of the present invention is the injection molding die according to claim 1, wherein
In order to arrange the gate and the spacer so as to overlap each other in the pressure acting direction, the spacer has a pair of other block portions facing each other in the direction orthogonal to the facing direction in addition to the pair of block portions facing each other in the spacing direction. It was provided, and it was decided that four block parts would surround the ejector space. The injection molding die according to claim 3 of the present invention is the injection molding die according to claim 1, in which the runner leading from the sprue to the gate is curved because the gate and the spacer are arranged to overlap each other in the pressure acting direction. It was decided to be formed in a shape.

[0009]

In the above-mentioned conventional technique, the cause of the bending of the mold due to the injection pressure or the mold clamping pressure is that the space due to the ejector space exists below the sprue, runner, gate and cavity. This is because the "reception" against the injection pressure or the mold clamping pressure was insufficient, and by reinforcing this "reception", it is possible to effectively suppress the occurrence of bending of the mold. From this viewpoint, the invention according to claim 1 of the present application is
The spacer is actively used as this "reception".

That is, in order to suppress the bending of the mold due to the injection pressure or the mold clamping pressure, the gate where the pressure peak occurs and the spacer having the ejector space are arranged so as to overlap in the pressure acting direction. When,
The spacer acts as a direct "receiver" for the injection pressure or the mold clamping pressure, and there is no space due to the ejector space in the gate pressure acting direction. As a result, the mold is bent in the same direction. Less likely to occur.

[0011]

As described above, the ejector space is conventionally set to have a relatively large occupying area in the plane. Therefore, in relation to this, the spacer is relatively small in the plane. It is set.
Therefore, in order to arrange the gate and the spacer so as to overlap each other in the pressure acting direction, it is often necessary to devise some means, and the present invention proposes the following two as means for that. First example: In order to arrange the gate and the spacer in the pressure acting direction so as to overlap each other, in addition to the pair of block portions spaced apart and opposed to each other, the pair of spacers opposed to each other in the direction orthogonal to the opposing direction. The other block parts are provided so that the four block parts surround the ejector space for convenience (claim 2). The four block portions may be separated from each other, but it is preferable to form the four block portions into a single plate shape having a space acting as an ejector space at the center of the plane. Second example: In order to arrange the gate and the spacer so as to overlap each other in the pressure acting direction, a runner leading from the sprue to the gate is formed in a curved shape in a part or all of its length direction (claim 3). ).

The first example and the second example can be combined, as is the case with the following embodiments.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings.

First Embodiment: As shown in FIGS. 1 to 4, the injection molding die according to the embodiment is a four-piece injection molding die, and FIG.
In this order, the fixed side mounting plate 1, the fixed side template 2, the movable side template 3, the receiving plate 4, the spacer 5 and the movable side mounting plate 6 are laminated in this order from the top. A parting surface 7 is provided between the mold plates 3 as shown in FIG.
As shown in FIG. 4, four runners 9 radially extend around the sprue 8 and communicate with the cavities 11 through the gates 10. Each of the cavities 11 has four ejector pins 12 in the shape of a field. It is arranged. In the mold, each gate 10 in which a pressure peak is generated and the spacer 5 in which the ejector space 13 is formed have a pressure acting direction so that the bending of the mold due to the injection pressure or the mold clamping pressure can be suppressed. 1 in the up-down direction, and in FIGS. 2 to 4 in the directions orthogonal to the paper surface), and more specifically, they are configured as follows.

That is, first, as shown in FIGS. 3 and 4, the pair of block portions in which the spacers 5 are spaced apart from each other and face each other so that the gates 10 and the spacers 5 are arranged to overlap each other in the pressure acting direction. In addition to 5a and 5b, a direction orthogonal to the facing direction (horizontal direction in the drawing) (vertical direction in the drawing)
A pair of other block portions 5c, 5d facing each other with a space between them
And the four block parts 5a, 5
b, 5c, 5d are integrally formed into a plate-shaped body, and the ejector space 1 is formed at the center of the plane.
3 are provided. Corresponding to that the four cavities 11 are evenly arranged around the sprue 8, the ejector plate 14 is formed in a substantially x-shaped plane so as to overlap with the sprue 8. The ejector plate 14 can be operated. The ejector space 13 accommodated therein is provided in a substantially planar X shape that is slightly larger than the ejector plate 14. That is, the spacer 5 formed in the shape of a single plate
A substantially x-shaped ejector space 13 is provided at the center of the plane, and an ejector plate 14 also having a substantially x-shaped plane is housed in the ejector space 13 so as to be vertically movable in FIG.

As described above, four ejector pins 12 are arranged in a field shape on each of the four radial pieces of the ejector plate 14, and the ejector space 1 is also provided.
Through holes 17 and 18 are provided through which the support pillars 15 and 16 arranged in the housing 3 are slidably inserted. Ejector pins 19 (one) projecting the sprue part of the molded product and ejector pins 20 (one for each runner 9) projecting the runner part of the molded product are provided at the central intersection of the ejector plate 14. There is. Ejector plate 1
Reference numeral 4 denotes two plates 14a and 14b so that the ejector pins 12, 19 and 20 are fixed at their large-diameter base ends.
Are laminated and integrated.

A runner 9 leading from the sprue 8 to each gate 10 is formed in a curved shape in a part thereof so that each gate 10 and the spacer 5 are arranged to overlap each other in the pressure acting direction. That is, as described above, the four runners 9 are evenly arranged around the sprue 8 and alternately with the cavities 11 in correspondence with the four cavities 11 being equally arranged around the sprue 8. Each runner 9 is formed in a substantially J shape in a plane with a straight-line portion (no reference numeral) on the upstream side and a curved portion 9a on the downstream side, and the gate 10 is provided at the tip of the curved portion 9a. Are arranged.
The planar shape of the four runners 9 is generally a substantially inverted swastika shape.
It should be noted that the runners 9 are made substantially J-shaped in plan view because the runners 9 are detoured in order to arrange the gates 10 and the spacers 5 in the pressure acting direction so as to be overlapped. Is.

Since the injection molding die according to the present embodiment is provided with the above-mentioned structure, each gate 10 where a pressure peak is generated and the spacer 5 having the ejector space 13 are overlapped in the pressure acting direction. Are arranged. Therefore, after the molten material such as resin reaches each gate 10 during injection, a large pressure acts downward from each gate 10 in FIG. 1, and this pressure presses the movable side mold plate 3 and the receiving plate 4 in the same direction. However, since the spacer 5 is arranged below the receiving plate 4 and is not a space as in the conventional case, the movable side mold plate 3 and the receiving plate 4 are largely bent in the same direction. According to a comparative test conducted by the inventors of the present application, the amount of bending can be suppressed to 10 μm or less. Therefore, since a large gap reaching 30 μm or more does not occur on the parting surface 7 as in the conventional case, the following effects can be obtained.

That is, first of all, the productivity can be improved because thick burrs, which require a unique removing operation after molding, do not occur. This also improves the dimensional accuracy of the product. Secondly, since the internal pressure of the cavity 11 does not decrease, the strength of the product can be improved.

Second and Third Embodiments The first embodiment described above was a four-cavity injection mold, but the present invention is not limited to a four-cavity injection mold. Widely applied to injection molding dies for multi-cavity production of two, three or more than five. Of these, FIG. 5 shows an example of taking two pieces and FIG. 6 shows an example of taking three pieces. For the reference numerals in both figures, refer to the first embodiment.

[0021]

The present invention has the following effects.

That is, first, in common with the first to third aspects, a gate having a pressure peak and a spacer having an ejector space are formed so that the bending of the mold due to the injection pressure or the mold clamping pressure can be suppressed. Since and are arranged in the pressure acting direction, the spacer acts as a direct “reception” for the injection pressure or the mold clamping pressure, and there is no space due to the ejector space in the pressure acting direction of the gate. As a result, it becomes difficult for the mold to bend in the same direction. Therefore, since a thick burr that requires a unique removing operation after molding does not occur, it is possible to improve the productivity and also improve the dimensional accuracy of the product. Moreover, since the internal pressure of the cavity does not decrease, the strength of the product can be improved. Further, according to the second and third aspects, it becomes easy to arrange the gate and the spacer so as to overlap each other in the pressure acting direction.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of an injection molding die according to the first embodiment of the present invention, which is a cross-sectional view taken along the line CC in FIG. 2 or FIG.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a sectional view taken along line BB in FIG. 1;

FIG. 4 is a partially enlarged view of FIG. 3;

FIG. 5 is a cross-sectional view of an injection molding die according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of an injection molding die according to a third embodiment of the present invention.

7 is a vertical cross-sectional view of an injection molding die according to a conventional example, which is a cross-sectional view taken along line FF in FIG. 8 or FIG.

FIG. 8 is a sectional view taken along line DD in FIG.

9 is a sectional view taken along line EE in FIG.

[Explanation of symbols]

 1 Fixed Side Mounting Plate 2 Fixed Side Mold Plate 3 Movable Side Mold Plate 4 Receiving Plate 5 Spacers 5a, 5b, 5c, 5d Block Part 6 Movable Side Mounting Plate 7 Parting Surface 8 Sprue 9 Runner 9a Curved Part 10 Gate 11 Cavity 12 , 19,20 Ejector pin 13 Ejector space 14 Ejector plate 14a, 14b Plate 15,16 Support pillar 17,18 Through hole

Claims (3)

[Claims] 1. A gate (10) where a pressure peak is generated and a spacer (5) having an ejector space (13) are pressured so that the bending of the mold due to the injection pressure or the mold clamping pressure can be suppressed. An injection-molding die characterized by being arranged in a stack in the direction of action. 2. The injection molding die according to claim 1, wherein a pair of spacers (5) are spaced apart from each other and face each other in order to arrange the gate (10) and the spacer (5) so as to overlap each other in the pressure acting direction. In addition to the block parts (5a) and (5b), a pair of other block parts (5c) and (5d) facing each other in a direction orthogonal to the facing direction are provided, and four convenient block parts (5a) ( A mold for injection molding, characterized in that 5b), (5c) and (5d) surround the ejector space (13). 3. The injection mold according to claim 1, wherein the sprue (8) leads to the gate (10) in order to arrange the gate (10) and the spacer (5) so as to overlap each other in the pressure acting direction. (9) is formed in a curved shape, an injection mold.