JP4847105B2 - Injection mold - Google Patents

Description

  The present invention has a structure for cooling a gear molded by a mold, and uniformly cools the gear (molded product), reduces local shrinkage difference, and reduces the occurrence rate of defects such as deformation. This is related to the metal mold.

When manufacturing a gear made of plastic or the like by injection molding, local temperature expansion causes local thermal expansion or contraction, which causes problems due to deformation or the like.
2. Description of the Related Art Conventionally, an injection mold having a cooling mechanism that uniformly cools a plastic gear (molded product) during molding, reduces a local shrinkage difference, and reduces a defect occurrence rate such as deformation is known (for example, Patent Documents 1 and 2).
FIGS. 9A and 9B are a front view and a plan view showing a gear molding injection mold having a cooling mechanism according to a conventional example. In the injection mold A having a cooling mechanism as shown in FIG. 9, when the cooling water pipe 4 is installed inside the thickness of the core plate 3 of the mold, the outer diameter side of the gear piece 2 on the core plate 3 is set. The cooling water pipe 4 is arranged. The cooling water pipe 4 is arranged in a U-shape or a square shape in addition to the linear shape as shown in FIG. By passing water through the cooling water pipe 4, the molded product located in the center is cooled.
JP 2001-113578 A JP 2003-326578 A

However, in the layout of the cooling water pipe 4 as shown in FIG. 9, the distance from each part of the gear as a molded product to the cooling water pipe varies, so even if water passes through the cooling water pipe, the gear piece 2 and the gear (molding) Product) is difficult to cool evenly. Therefore, the cooling efficiency to the gear piece 2 and the molded product in the central portion is lowered.
That is, since there is a distance between the cooling water pipe 4 and the gear piece 2, there is a problem that the cooling efficiency is poor, and as a result, the dimensional accuracy of the gear is lowered and the cycle time is increased.
Further, in the case of adopting a mechanism for rotating the gear piece 2 during molding with a mold for forming a helical gear or the like, the inside of the gear piece 2 and the gear piece 2 for the rotational operation of the gear piece 2 It was difficult to arrange the cooling water pipe 4 in the contact area.
In view of the above situation, an object of the present invention is to provide a groove for fitting the fixing piece inside the gear piece, to process a water pipe in the fixing piece, and to provide an O-ring for preventing water leakage. It is an object of the present invention to provide an injection mold that can directly cool a gear piece, facilitates temperature control, shortens cycle time, and makes it possible to manufacture a molded product with stable accuracy.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an injection mold having a gear piece having a molding surface for molding a gear-shaped molded product. , provided a recess for accommodating the fixing piece fixed to the backup plate, the the fixed frame is provided that water channel therein, which characterized in that the gear frame relative to the fixed piece is detachably .
According to a second aspect of the present invention, in the injection mold according to the first aspect, the water passage is formed in a cylindrical shape surrounding the gear piece on the outer diameter side thereof.
According to a third aspect of the present invention, in the injection mold according to the first or second aspect, the recess inner wall of the gear piece and the outer wall of the fixed piece are inclined surfaces that engage with each other in an aligned state. It is characterized by that.
According to a fourth aspect of the present invention, in the injection mold according to the first, second, or third aspect, the shape of the fixed piece is standardized.

  According to the present invention, in an injection mold having a cooling water passage inside the mold, a groove (recess) for fitting the fixing piece is provided inside the gear piece, and the water pipe (flow passage) is provided in the fixing piece. As a result, the gear piece can be directly cooled, temperature control becomes easy, cycle time is shortened, and a molded product having stable accuracy can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a first embodiment of a mold structure for improving the cooling of a gear piece by providing a fixed piece in the gear piece according to the present invention. 2 is an enlarged schematic cross-sectional view showing the left side of the mold structure of FIG. FIG. 3 is a schematic cross-sectional view showing how the fixed piece is fitted into the gear piece.
1 to 3, in this mold structure, the fixed piece 1 is provided inside the gear piece 2 so that the cooling of the gear piece 2 is improved. An injection mold having a cooling mechanism is provided with a groove (recess) 2 a for fitting the fixed piece 1 inside the gear piece 2.
A water pipe (water passage) 4 is processed in the thickness of the fixed piece 1, and an O-ring 8 is provided between the water pipe 4 and the backup plate 5 to prevent water leakage. The fixed piece 1 is configured to be fitted into the groove 2a of the gear piece 2 as shown in FIG.
That is, in the present embodiment, in the injection mold having the gear piece 2 having the molding surface 2A (cavity) for molding a gear-shaped molded product, the recess 2a provided in the thickness of the gear piece 2 is provided. The configuration is characterized in that the fixed piece 1 is accommodated therein and a water pipe (water passage) 4 is disposed in the fixed piece 1. Two water pipes 4 are arranged in the fixed piece 1, one water pipe 4 is a side into which cooling water is poured, and the other water pipe 4 is a side from which circulating cooling water is discharged. Each water pipe 4 communicates with passages 6 and 7 in the backup plate 5.
The backup plate 5 presses and fixes the end face of the fixed piece 1 mounted from the opening side of the recess 2a, and makes one end of each water pipe 4 communicate with each passage 6,7. Each of the passages 6 and 7 is connected to a water supply source by a water pipe plug 9 connected to each end thereof, so that cooling water can be poured into the fixed piece 1.
One water pipe 4 is a side through which cooling water flows, and the other water pipe 4 is a side from which circulating cooling water is discharged. Cooling water having a constant temperature always flows through the fixed piece 1. By installing them, the gear piece 2 can be directly cooled, temperature control becomes easy, cycle time can be shortened, and a gear (molded product) 12 (see FIG. 6) with stable accuracy can be provided. .

FIG. 4 is a schematic top view showing a second embodiment of the mold structure for improving the cooling of the gear piece by providing the fixed piece in the gear piece in the present invention. FIG. 5 is a longitudinal sectional front view showing a second embodiment of the mold structure of FIG.
4 and 5, in this injection mold, a cylindrical water pipe (cylindrical water passage) 10 is provided inside the fixed piece 1. The cylindrical water pipe 10 is configured in a cylindrical shape that surrounds the gear piece 2 on the outer diameter side.
By encircling most of the gear piece by the cylindrical water pipe 10, it becomes possible to pour cooling water into the entire inside of the gear piece 2 and to circulate it.
As a result, the cooling efficiency of the gear piece 2 is improved and the entire gear piece 2 has a uniform temperature distribution. Further temperature control of the gear piece 2, shortening of the cycle time, and stable precision gear (molded product) 12 (see FIG. 6). ) Can be provided.

FIG. 6 is a schematic cross-sectional view showing a third embodiment of the mold structure for improving the cooling of the gear piece by providing the fixed piece in the gear piece according to the present invention. In the third embodiment shown in FIG. 6, the outer wall of the fixed piece 1 and the inner wall of the groove 2 a of the gear piece 2 are each provided with a taper (inclined surface) 11.
The gear piece 2 also moves in the same direction as the gear (molded product) 12 due to the release resistance when the gear (molded product) 12 protrudes. Since the fixed piece 1 is fixed to the backup plate 5, if the fixed piece 1 and the gear piece 2 are aligned with the taper 11, a clearance is generated there, and the rotation of the gear piece 2 becomes smooth.
FIGS. 7A and 7B are a front view and a plan view showing a fixed piece whose shape is standardized. In the embodiment shown in FIG. 7, the shape of the fixed piece 1 is standardized. If the shape of the fixed piece 1 is standardized according to the size of the mold and gear (molded product) 12 (see FIG. 6), one fixed piece 1 can be used for several types of molds (recycled). And the resource usage rate can be reduced.
FIGS. 8A and 8B are a front view and a plan view of a fixed piece in which the shape of FIG. 7 using a steel material having high thermal conductivity is standardized. In the embodiment shown in FIG. 8, the fixed piece 1 is made of a steel material having high thermal conductivity. The cooling efficiency of the gear piece can be further increased by making the fixing piece 1 a steel material (for example, BeCu) having high thermal conductivity.

It is the schematic which shows 1st Embodiment of the metal mold | die structure for providing the fixed piece in this invention inside a gear piece, and improving the cooling of a gear piece. It is a schematic sectional drawing which expands and shows the left side of the metal mold | die structure of FIG. It is a schematic sectional drawing which shows a mode that a fixed piece is engage | inserted inside a gear piece. It is a schematic top view which shows 2nd Embodiment of the metal mold | die structure for providing the fixed piece in this invention inside a gear piece, and improving the cooling of a gear piece. It is a cross-sectional front view which shows 2nd Embodiment of the metal mold | die structure of FIG. It is a schematic sectional drawing which shows the 3rd Embodiment of the metal mold | die structure for providing the fixed piece in this invention inside a gear piece, and improving the cooling of a gear piece. It is a top view which shows the fixed piece with which the shape is standardized with a schematic sectional drawing. It is a top view which shows the fixed piece in which the shape of FIG. 7 using the steel material with high conductivity is standardized with a schematic sectional view. It is the schematic which shows the prior art example of the injection mold which has a cooling mechanism with a front view.

Explanation of symbols

1 Fixing piece 2 Gear piece 3 Core plate 4 Water pipe (cooling mechanism)
5 Back-up plate 6 Back-up plate water pipe outlet 7 Back-up plate water pipe inlet 8 O-ring 9 Water pipe plug 10 Cylindrical water pipe 11 Taper 12 Gear (molded product)

Claims (4)

In an injection mold having a gear piece with a molding surface for molding a gear-shaped molded product,
A recess for accommodating a fixed piece fixed to a backup plate is provided inside the thickness of the gear piece , and a water passage is provided in the fixed piece , and the gear piece is detached from the fixed piece. Injection mold characterized by being free.   The injection mold according to claim 1, wherein the water passage is formed in a cylindrical shape surrounding the gear piece on the outer diameter side thereof.   3. The injection mold according to claim 1, wherein the recess inner wall of the gear piece and the outer wall of the fixed piece are inclined surfaces that engage with each other in an aligned state.   The injection mold according to claim 1, 2, or 3, wherein the shape of the fixed piece is standardized.

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