JP2544595Y2 - Cross type leaf spring forming mold - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention has a thin portion crossing in an X-shape and a thick connecting portion on both sides thereof, for example, like a cross-type leaf spring for tracking and supporting an objective lens in an objective lens actuator. The present invention relates to a cross-shaped leaf spring forming die used for resin-forming a symmetrical cross-shaped leaf spring.

[0002]

2. Description of the Related Art As an intersecting leaf spring for supporting the tracking of an objective lens, a thin portion 1 (1a, 1b, 1c, 1d) intersecting in an X-shape as shown in FIG. An intersecting leaf spring 4 having a symmetrical shape with respect to the axis of symmetry L having the connecting portions 2 and 3 is used. One joint 3 of the cross-type leaf spring 4 is joined to the objective lens holder, and the other joint 2 is joined to a parallel leaf spring composed of two parallel upper and lower sheets for focusing support. A conventional mold used for injection molding of this type of intersecting leaf spring 4 is shown in FIG.
As shown in FIG. 6, the gates 7, 8, runners 9, 10 and sprue 11 of the mold 6 are formed in the cavity 1 (use the same reference numerals as those of the cross-type leaf spring 1 as a molded product)
Are disposed asymmetrically with respect to the axis of symmetry L. In addition,
In FIG. 6, 6A indicates a fixed mold, and 6B indicates a movable mold.

[0003]

When the resin is molded using the mold 6 having the above structure, the gates 7 and 8 and the runners 9 and 10 are asymmetrical. Each of the four thin portions 1a, 1b,
The timing at which the resin flows into 1c and 1d is different, so that shear stress remains as residual stress in one of the four thin portions 1a, 1b, 1c and 1d. That is,
Of the four thin portions 1a, 1b, 1c, 1d, 1c, 1d
Is filled evenly, but in 1a and 1b, filling of 1a is performed first and 1b is delayed, so even if the resin is filled in 1a, the portion of 1b is still filled. The pressure during injection continues to be applied to the part. Therefore, a residual stress is generated in the portion 1a during the curing process. If the residual stress is relaxed after molding, there is a problem that the leaf spring is deformed.

In particular, the cross-type leaf spring of the objective lens actuator has a small overall length of, for example, about 2 cm and an extremely thin thickness of, for example, about 0.2 mm. Filling is not always easy. In addition, as the resin material, a polyester elastomer having a high elasticity is often used because of the requirement for the function as a leaf spring. However, since this polyester elastomer has poor fluidity, it is difficult to form an extremely thin portion in this respect. The above problem is likely to occur.

The present invention has been made in order to solve the above-mentioned conventional disadvantages. When a cross-type leaf spring having a thin portion is molded with a resin, the occurrence of residual stress at the time of molding is prevented to prevent deformation after molding. The purpose is to prevent occurrence.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. The present invention relates to a method of forming a bilaterally symmetrical cross type leaf spring having a thin portion crossing in an X-shape and a thick connecting portion on both sides thereof. Wherein the sprue is arranged on the axis of symmetry of the cavity, and the runner and the gate are arranged symmetrically with respect to the axis of symmetry of the cavity.

The invention according to claim 2 is characterized in that the gate is disposed so as to open to a cavity corresponding to the joint.

[0008]

In the above construction, the molten resin injected from the nozzle of the molding machine passes through the sprue, passes through the runner, and is injected into the cavity from the gate. Since both the runner and the gate are arranged symmetrically with respect to the axis of symmetry of the cavity, the molten resin is filled into the thin portion of the cavity at the same time, so that the occurrence of residual stress during molding can be avoided. In addition, the occurrence of deformation after molding can be eliminated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The cross-type leaf spring to be formed in this embodiment is as shown in FIG. A mold 20 for injection-molding the intersecting leaf spring 4 has an axis of symmetry of a cavity 4 of a molded product which is symmetrical in the left and right direction (the cavity in the mold also uses the same reference numeral as the intersecting leaf spring 4 which is a molded product). L, and two runners 22 and 23, which extend symmetrically in a U-shape from both sides of the sprue 21 and reach the left and right side portions of the joint 2 far from the sprue 21, and the sprue 21. The axis of symmetry L
Runners 24 extending along the center of the joint 3 closer to the sprue 21 and each runner 22, 23,
Gate 2 communicating with cavity 4 at the tip of 24
5, 26, and 27. That is, sprue 2
1 is on the axis of symmetry L of the cavity 4 and the runner 2
2, 23, 24 and gates 25, 26, 27 are symmetric about the axis of symmetry L of the cavity 4. FIG. 2, FIG.
In the figure, 20A indicates a fixed mold, and 20B indicates a movable mold.

When performing injection molding of the intersecting leaf spring 4 by the above-described mold 20, molten resin injected from a nozzle of an injection molding machine (not shown) passes through a sprue 21 and passes through runners 22 and 23 on the left and right sides thereof. Is injected into the cavity 4 from the gates 25 and 26 on the left and right side portions of the connection portion 2 which is farther away,
And, it is injected into the cavity 4 from the gate 27 at the center of the joint 3 which is closer through the runner 24. In this case, the runners 22, 23, 24, gates 25, 26, 2
7 are symmetrical with respect to the axis of symmetry L of the cavity 4, the molten resin contains four thin portions 1 a of the cavity 4,
1b, 1c and 1d are filled at the same timing, so that the occurrence of residual stress during molding can be avoided,
The occurrence of deformation after molding can be eliminated.

The shape of the intersecting leaf spring is not necessarily limited to the illustrated shape, but may be any symmetrical shape having a thin portion intersecting in an X-shape and thick connecting portions on both sides thereof.

Further, the structure of the mold is not limited to the structure shown in the drawing. For example, both the joints 2 and 3 may have a structure in which a resin is injected from both side surfaces thereof. It is sufficient that the arrangement of the runners is symmetric.

[0013]

According to the present invention, the sprue is arranged on the axis of symmetry of the cavity, and the runner and the gate are arranged symmetrically with respect to the axis of symmetry of the cavity. When molding resin,
It has become possible to prevent the occurrence of deformation after molding by preventing the occurrence of residual stress during molding.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view of a main part showing an embodiment of a cross-type leaf spring forming die of the present invention.

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

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

FIG. 4 is a perspective view showing an example of a cross-type leaf spring to be formed by the mold of the present invention.

FIG. 5 is a horizontal sectional view of a main part of a conventional mold for forming a cross-type leaf spring.

FIG. 6 is a sectional view taken along line CC in FIG.

[Description of References] 1, 1a, 1b, 1c, 1d Thin portion of cross-type leaf spring (thin portion of molded product in mold cavity is also denoted by the same reference numeral) 2, 3 Joint of cross-type leaf spring ( 4 The crossing type leaf spring (the cavity of the mold is also represented by the same reference numeral) 20 the mold 21 sprue 22, 23, 24 runner 25, 26, 27 gate L cavity symmetry axis

Claims (2)

(57) [Scope of request for utility model registration] 1. A cross-shaped leaf spring forming die used for resin molding of a bilaterally symmetrical cross-shaped leaf spring having a thin portion intersecting in an X-shape and thick connecting portions on both sides thereof. A cross-shaped leaf spring forming die, wherein the sprue is arranged on the axis of symmetry of the cavity, and the runner and the gate are arranged symmetrically with respect to the axis of symmetry of the cavity. 2. The mold for forming a cross-type leaf spring according to claim 1, wherein the gates are arranged so as to open to cavities corresponding to the respective joints.