JPH0957786A - Insert molding and molding thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insert molding in which finishing precision and outward appearance are good concerning a die of an insert molding. SOLUTION: An axial directional runner 32 is formed along an axial center of the upper end face of a metallic shaft 21 to the inside. A plurality of radial directional runners 33... are branched from the axial directional runner 32 and formed at equal adjacent angles. The radial directional runners 33 are opened on the surface of the metallic shaft 21 to form a gate 34. A cavity 35 for a gear 22 is positioned herein. When a molten resin 40 is poured from the end face of the metallic shaft 21, the resin is symmetrically spread from its axial center to the radial direction. When the resin is solidified, the gear 22 of a solidification state is formed in which uniform roundness is high. A remaining trace and a flow mark of the gate do not entirely exist on the surface of the gear 22. The resin in a radial directional runner 33 part which remains in the metallic shaft 21 fills the role of whirl-stop and come-out prevention of resin in the gear 22 part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to insert molding and a molded product thereof, and more particularly to an improved resin injection path into a cavity.

[0002]

2. Description of the Related Art Products in which metal parts and resin parts are integrated are generally produced by insert molding. In this method, a metal part is inserted into a cavity formed in a desired resin part shape and injection molding is performed to integrate the resin and the metal part. For example, a driver having a plastic handle is manufactured. Etc.

According to this method, there is no need for a secondary process of assembling the metal parts and the resin parts after forming the resin parts, as in the case of individually forming the resin parts, and the resin parts and the metal parts are not required. The integration of is also strong.

By the way, in not only the insert molding but also the injection molding in general, the gate which is the injection port of the resin into the cavity is provided on the cavity surface corresponding to the surface side when the resin is solidified, so that the mold After the mold release, when the runner and the product part are separated, irregularities and flow marks remain as gate marks on the surface of the solidified resin. In particular, when molding a cylindrical or spherical resin product, it is preferable to provide as many gates as possible at symmetrical positions on the cylindrical surface or the spherical cavity surface in order to improve the roundness, but in this case, However, many gate marks will remain.

[0005]

In the case of precision resin parts and the like, the above-mentioned gate marks remaining on the solidified resin have a great influence on the finishing accuracy of the parts, so the treatment of the gate marks is particularly careful. However, if there are many gates, the work will be very troublesome. In addition, the flow mark is a great obstacle in the case of products where the appearance is important.

Further, a die having many gates is complicated in processing and costly, and injection molding using such a die causes a large loss of resin.

[0007] Therefore, an object of the present invention is to reduce or eliminate the gate provided on the cavity surface corresponding to the surface of the target component in insert molding, and to obtain an insert molded product with good finish accuracy and appearance. Especially.

[0008]

In order to solve the above-mentioned problems, a first invention is to insert an insert part into a mold cavity having a desired shape, and insert the insert part and a resin part having a desired shape by injection molding. In the insert molding to be integrated, a runner continuous with the sprue of the mold is formed inside the insert part, and a downstream of the runner is opened on the surface of the insert part, and molten resin is passed from the sprue through the runner. The insert-molded product is obtained by injecting it into the cavity having the desired shape.

In this way, the molten resin flows into the cavity from a position corresponding to the back surface side (or inner surface side) of the solidified resin component.

A second aspect of the present invention is an insert-molded product in which an insert part and a resin part having a desired shape are integrated by injection molding, wherein the resin part includes a runner that opens through the inside of the insert part to the surface of the insert part. ,
That is, it is formed over the desired shape connected to the runner.

In this insert-molded product, the runner-shaped resin is not formed on the surface of the resin component having the desired shape.

A third aspect of the invention is an insert-molded article in which the insert part is a metal plate, and a resin part having a desired shape is integrated with the metal plate, wherein the resin part is provided on one surface side of the metal plate. The runner thus formed, the through hole which is continuous with the runner and penetrates through the metal plate, and the desired shape which is arranged on the other surface of the metal plate where the through hole opens are formed. .

In this insert-molded product, the runner-shaped resin is not formed on the surface of the resin component having the desired shape.

A fourth aspect of the present invention is an insert-molded article in which the insert part is a metal shaft, and a resin part having a desired shape is integrated with the metal shaft. Direction,
That is, it was formed over a runner opening on the surface of the metal shaft and a desired shape arranged in line with the runner.

In this insert-molded product, the runner-shaped resin is not formed on the surface of the resin component having the desired shape.

[0016]

1 to 3 show a first embodiment of the present invention. This is a substrate 10 of a rotating mechanism used in a facsimile, a cassette tape recorder, a video tape recorder, etc., and various resin parts 2, ... Are formed on a metal plate 1 which is an insert part, as shown in FIG. It is an insert molded product.

The surface of the metal plate 1 opposite to the surface on which the resin component 2 is formed (hereinafter referred to as the front surface 3) (hereinafter referred to as the rear surface 4) is shown in FIG. As shown, a resin plate 5 having a constant thickness and a predetermined planar shape is formed corresponding to each resin component 2, and each resin plate 5 has a predetermined diameter at a predetermined position in the planar shape. It vertically penetrates the metal plate 1 and is connected to the corresponding resin component 2. Mold 1 for substrate 10 of such a rotating mechanism
1 is configured as follows.

Before injection molding, in a state where the metal plate 1 which is an insert part is fixed to the mold 11 at a predetermined position, as shown in FIG. 3, the cavity 52 of the resin part 2 on the surface 3 thereof, The cavity 55 of the resin plate 5 on the back surface 4 is connected through a through hole 6 provided at a predetermined position of the metal plate 1. And
The gate 7 is placed at a predetermined position in the cavity 55 of the resin plate 5.
Is provided.

The molten resin 40 is added to the mold 11 having the above construction.
When the resin is injected, the molten resin 40 enters the cavity 55 of the resin plate 5 from the sprue 12 of the die 11 through the gate 7 as shown by the arrow in the figure, and the metal plate 1
It reaches the cavity 52 of the resin component 2 through the through hole 6.

That is, in this mold 11, the cavity 55 of the resin plate 5 and the through hole 6 become the runners 15 and 16 reaching the cavity 52 of the resin component 2, respectively, and a part of the runner is the metal plate 1 itself which is an insert component. It is in the form provided in. Thereby, as described above, the gate 7 is provided on the cavity 55 side of the resin plate 5 on the back surface 4 and avoiding the provision on the cavity 52 side of the resin component 2.

In this way, there are no gate marks or flow marks on the surface of the solidified resin component 2.
For example, as for the gear parts on the metal plate 1 shown in the drawing and the like, which is particularly required to have a high finishing accuracy, a very accurate one can be molded. Moreover, the resin plate 5 also serves as a retainer for the resin component 2.

In addition, providing the gate 7 on the resin plate 5 which can be set in a simple plane shape is different from forming the gate directly in the cavity 52 of the resin component 2 having an arbitrary complicated three-dimensional shape. The die shape is remarkably simplified, the processing is facilitated, the processing time is shortened, and the cost of the die processing is significantly suppressed. Since this resin plate 5 is a portion that is not visible to the outside, if the complexity and cost of die processing are taken into consideration, a large number of gates 7 are provided at symmetrical positions on the surface of the cavity 55 so that the resin flow path difference is eliminated. Therefore, the resin component 2 having a more uniform content can be molded.

Further, in the cavity 55 of the resin plate 5, the runner 15 which is a protrusion is formed on the back surface 4 of the metal plate 1. However, as shown in FIGS. 4 and 5, the groove 17 is formed on the back surface 4. If the groove 17 is provided and the groove 17 is used as the runner 18, the back surface 4 can be made completely flat after the resin is solidified, so that the back surface 4 can be attached to another flat surface.

Next, a second embodiment of the present invention is shown in FIGS. As illustrated, the gear shaft 20 is an insert-molded product in which a resin gear 22 is integrated with a metal shaft 21. In this case as well, the runner and gate, which are the constituent elements of the mold, are formed on the metal shaft 21 itself, which is the insert part, and the runner and gate of this insert part are incorporated into a part of the mold to perform insert molding.

As shown in FIG. 7, the metal shaft 21 alone of the gear shaft 20 has a sprue 31, which is a molten resin injection port, formed at the center of its upper end surface. And
An axial runner 32 is formed inside the metal shaft 21 from the sprue 31 along the axis thereof. At a position where the axial runner 32 has advanced a predetermined distance, a plurality of radial runners 33, ... Branching from the axial runner 32 are formed in the radial direction. The radial runner 33 opens on the surface of the metal shaft 21 to form a gate 34,
As will be shown later, the cavity 35 for the gear wheel 22 is located at the position of the gate 34.

The plurality of radial runners 33, ... Are directed toward the surface of the metal shaft 21 with the same angle between adjacent ones in the circle of the cross section of the metal shaft 21. This is because the molten resin has a radial runner 33.
The position where each of the gates 34 is injected into the cavity 35, that is, the position of each of the gates 34 on the surface of the metal shaft 21 described above is symmetrically positioned within the cavity 35. By doing so, when the molten resin starts from the gate 34 and spreads in the cavity 35 under the same conditions, and when the resin is solidified, there is no unevenness in the solidified state due to the position of the gear 22.

The metal shaft 21 having the above-mentioned shape is
It is inserted into the cavity 35 for the gear wheel 22 having a predetermined size and shape. At this time, the opening of the radial runner 33, that is, the gate 34 is located at the position of the cavity 35 of the gear 22, and the axis of the metal shaft 21 and the axis of the cavity 35 of the gear 22 are aligned with each other. The metal shaft 21 is fixed so as to match. Thus, the mold 30 incorporating the metal shaft 21 that is an insert part
Is set.

In the die 30 set in this way, the sprue 31 on the end face of the metal shaft 21 described above is used.
When the molten resin 40 is injected from, the molten resin 40 moves along the axial runner 32 as shown by the arrow in the figure, passes through the radial runner 33, and is injected from the gate 34 on the surface of the metal shaft 21 into the cavity 35 of the gear 22. . When the molten resin 40 is solidified in the cavity 35, the gear shaft 20 in which the resin gear 22 is integrated with the metal shaft 21 is formed as shown in FIG.

When insert molding is performed using the mold 30 having the above-described structure, the gate 34 is formed on the surface of the metal shaft 21.
That is, since it exists at the position of the inner surface of the shaft hole of the gear 22,
Since there are no gates on the surface of the gear 22 and it is not necessary to treat the gate marks, the gear 22 can be manufactured with extremely high precision without trouble.

In particular, in the case of molding a cylindrical or spherical resin product such as this gear, in order to increase the roundness, as much as possible at symmetrical positions of the cylindrical surface or the spherical cavity surface. It is preferable to provide a gate to reduce the flow path difference so that the molten resin is evenly filled in the cavity under the same conditions, but this method does not require any consideration of the gate mark on the surface. Therefore, many gates can be provided on the inner surface side of the resin gear, and resin parts with high roundness can be molded, if the labor and cost of the processing are taken into consideration.

Furthermore, when the mold is released, the metal shaft 2
The resin of 32 axial runners in 1 is extracted to the outside,
The resin in the axial runner 32 part and the resin in the radial runner 33 part are automatically cut and separated. And the metal shaft 2
Since the resin in the radial runner 33 portion remaining in 1 and the resin in the gear 22 portion on the surface of the metal shaft 21 are connected to each other, the resin in the radial runner 33 portion prevents the resin in the gear 22 portion from rotating and coming off. Play a role.

In this die 30, as described above,
A runner (axial runner 32) is provided in the shaft from the upper end surface of the metal shaft 21 which is an insert part to form the molten resin 4
Since 0 is injected, as shown in FIG. 7, when the molten resin 40 is injected, the pressure of the molten resin 40 existing in the sprue space 36 may press the upper end surface of the metal shaft 21 toward the lower end surface. The lower end surface (not shown) can be pressed against the wall of the mold (not shown). Therefore, even if the length of the metal shaft 21 is shorter than the desired length,
The distance from the lower end surface (not shown) of the metal shaft 21 to the reference position of the gear 22 is always kept constant.

On the other hand, if the cavity 35 of the gear 22 is provided with the gate itself, a mechanism for fixing the metal shaft 21 in the length direction must be provided separately, and even in that case, the finished length of the metal shaft 21 is also increased. When the molten resin 40 is injected, the metal shaft 21 swings in the axial direction by the pressure of the resin when the molten resin 40 is injected, and the lower end surface of the metal shaft 21 floats up from the mold wall, and the lower end surface of the metal shaft 21 of the gear 22. Fixed position from can not be constant.

[0034]

As described above, according to the present invention, a runner is formed in the insert part in insert molding, and the downstream opening of the runner is connected to the cavity of the desired resin part. Since the runner has a mold structure that connects to the back side of the solidified resin component,
No gate mark or flow mark appears on the surface of the solidified resin component, and an insert molded product excellent in accuracy and appearance can be obtained.

In particular, the present invention is applied to an axially symmetric insert molded product such as a gear shaft in which the insert part is a metal shaft and a resin gear is fitted in the metal shaft, and the shaft in the metal shaft is If an axial runner is provided along the core, radial runners branching from the axial runner and forming the same adjoining angle are opened on the shaft surface, and a cavity for the gear portion is provided at that position to form a mold structure connected to this.
Since many gates can be provided on the inner surface of the gear without considering the gate marks on the surface of the gear at all, a molded product having a high roundness can be obtained.

Since the resin solidified by the runner in the insert part is connected to the corresponding resin part,
After releasing the mold, it can play the role of preventing the resin part from coming off from the insert part and preventing the resin part from rotating, which can significantly improve the efficiency of the design and manufacturing process.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of the above.

FIG. 3 is a sectional view showing a first embodiment of the present invention.

FIG. 4 is a perspective view of an essential part of the above.

FIG. 5 is a sectional view of a main part of the above.

FIG. 6 is a perspective view of an essential part showing a second embodiment of the present invention.

FIG. 7 is a sectional view of an essential part showing the injection molding of the above.

[Explanation of symbols]

 1 Metal Plate 2 Resin Part 3 Front Surface 4 Back Surface 5 Resin Plate 6 Through Hole 7, 34 Gate 10 Substrate 11 Mold 12, 31 Sprue 15, 16, 18 Runner 17 Groove 20 Gear Shaft 21 Metal Shaft 22 Resin Gear 32 32 Axial Runner 33 radial runner 35, 52, 55 cavity 36 sprue space 40 molten resin

Claims (4)

[Claims] 1. In insert molding in which an insert part is inserted into a mold cavity of a desired shape and the insert part and a resin part of a desired shape are integrated by injection molding, a runner continuous with a sprue of the mold is the insert. The insert is formed inside the part, and the downstream of the runner is opened to the surface of the insert part, and the molten resin is injected from the sprue, through the runner, and into the cavity of the desired shape to obtain an insert molded product. Insert molding characterized by. 2. An insert-molded article in which an insert part and a resin part having a desired shape are integrated by injection molding, wherein the resin part includes a runner that opens into the surface of the insert part through the inside of the insert part and the runner. An insert-molded product, characterized in that it is molded over a series of the desired shapes. 3. An insert molded article in which the insert part is a metal plate and a resin part having a desired shape is integrated with the metal plate, wherein the resin part is a runner formed on one surface side of the metal plate. And an insert formed through the through hole penetrating the metal plate in a row with the runner and a desired shape arranged on the other surface of the metal plate where the through hole opens. Molding. 4. The insert part is a metal shaft,
In an insert-molded product in which a resin component having a desired shape is integrated with the metal shaft, the resin component is connected to the runner, which extends axially in the metal shaft from its end face and opens on the metal shaft surface, and the runner. An insert-molded product characterized by being molded over a desired shape that is arranged in a line.