JPH10235651A - Positioning structure of mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the reliability of the positioning of split molds by means of bushings in positioning holes and positioning pins fitting to the holes for a long period of time. SOLUTION: Each positioning hole 11 opened in a portion in the neighborhood of each one of four corners of a split mold 10 has an elongated circle extending to the direction of a straight line passing through the center of the split mold 10. Both the inner surfaces in the direction of a short diameter of the elongated circle are planar parts 11a parallel to that straight line. To each positioning hole 11, a bushing 12 is fitted movably to the direction of that straight line under the state that its both side planar parts 121a come into close contact with the planar parts 11a of the positioning hole 11. As a result, at mold closing, even when the axis centers of the positioning pins 21 and of the bushings 12 of a split mold 20 shift each other due to the difference between the thermal expansions of the split molds 10 and 20, the bushings 12 move to the concentric positions of the split molds to the directions of the straight lines during the inserting process of the positioning pins 21 for self-alignment, resulting in developing no seizure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for forming a cavity with a plurality of divided dies used for molding a synthetic resin product or a rubber product. The present invention relates to a mold positioning technique for positioning.

[0002]

2. Description of the Related Art In a mold used for vulcanization molding of a rubber product, when a divided mold facing each other is abutted and closed, the cavity filled with a molding material has an abutment of the divided mold. So that they do not shift from each other on the surface (parting surface)
It is necessary to position the split molds accurately. Conventionally, for this positioning, a positioning hole is opened in one of the split dies, a bush is provided in this positioning hole, and a positioning pin is provided at a position corresponding to the bush in the other split mold, and when closing the die, The positioning pin and the bush are fitted to each other.

[0003]

The above prior art has the following problems. That is, since the mold is heated to a predetermined temperature by the hot platen, when the size of each split mold is different from each other, or between the upper and lower split molds that are always heated by the hot plate, In the case where an intermediate split mold is taken in and out, a difference in the amount of thermal expansion occurs due to a temperature change of the intermediate split mold. For example, as shown in FIG. The inner peripheral hole 102a and the positioning pin 104 provided on the other split mold 103 are slightly displaced in a straight line direction (radiation direction) passing through the center of the mold. As a result, when closing the mold, the bush 102 and the positioning pin 104 are displaced. Is "gnawing"
May cause premature wear and breakage.

The present invention has been made in view of the above circumstances, and a technical problem thereof is to improve the reliability of positioning of a split mold by a bush and a positioning pin fitted therein for a long time. It is to provide a positioning structure that can be maintained.

[0005]

Means for Solving the Problems The technical problems described above are:
This can be effectively solved by the present invention. That is, the positioning structure according to the present invention includes an opening-shaped positioning hole that is opened at three or more locations in one of the split dies and extends in a linear direction passing through the center of the die, and the positioning hole is slidably movable in the longitudinal direction. A bush fitted to the other split mold, and a positioning pin protruding in the mold closing direction corresponding to substantially the center of the positioning hole and capable of being inserted into the inner peripheral hole of the bush in a closely fitted state. . The relative displacement between the positioning hole and the positioning pin due to the difference in the amount of thermal expansion of each split mold occurs along a straight line passing through the center of the mold, but according to the present invention, in response to such a displacement, Since the bush is movable in the longitudinal direction (in the direction of the straight line) in the elongated positioning hole, "galling" with the positioning pin does not occur.

Further, since the three or more positioning holes into which the bush is fitted extend in mutually different directions, when the positioning pin and the bush are fitted together, the bush freely moves in the positioning hole together with the positioning pin. It cannot move, that is, the positioning function is not impaired by making the positioning hole into a long opening shape.

In the above configuration, it is more preferable that the bush and the positioning hole are in contact with each other on a plane parallel to a straight line passing through the center of the mold. That is, for example, when the bush has a cylindrical shape, the outer peripheral surface of the bush and the long hole-shaped positioning hole are in linear contact with each other. It is feared that the wear progresses early and the positioning function is impaired.However, if the contact area between the planes is increased to increase the contact area, the wear can be suppressed, so that a good positioning function can be provided for a long time. Will be maintained.

[0008]

1 to 5 show an embodiment of a mold positioning structure according to the present invention. In these figures, reference numerals 10 and 20 denote split dies which are arranged to face each other, and abut the opposing surfaces thereof to define a cavity (not shown) filled with a molding material therebetween. You. In FIG. 5, a region 10a surrounded by a two-dot chain line is a region where the cavity is formed.

The lower split mold 10 in the perspective views of FIGS. 1 and 2 has positioning holes 1 near its four corners.
1 has been established. As shown in FIG. 5, the positioning hole 11 has a cocoon-shaped opening shape corresponding to a movement trajectory when a circle is moved in a direction of a straight line L passing through the center O of the split mold 10. The inner surfaces on both sides in the short diameter direction are flat portions 11a parallel to the straight line L and perpendicular to the parting surface (upper surface) of the split mold 10. Preferably, the flat portion 11a is finished smoothly so as to have low friction.

A bush 12 made of a synthetic resin is fitted into each of the positioning holes 11. The bushing 12 is, H _R C48 to 53 about a metal material such as SK-5 was heat-treated to the hardness, A-A in FIG. 3 or FIG. 3
As shown in FIGS. 4 (A) and 4 (B), which are cut at the positions of the line and the line BB, the cylindrical portion 121 is slidably inserted in the positioning hole 11 in the longitudinal direction, and the upper and lower ends of the cylindrical portion 121 are prevented from coming off. Collar 1
22, 123. The flange 123 at the lower end
Is a product formed as a separate member, which is bonded after inserting the tubular portion 121 into the positioning hole 11, but when the bush 12 is made of a material having a certain degree of flexibility, the tubular portion 121 is used. Alternatively, they may be formed integrally.

On the outer peripheral surface of the cylindrical portion 121, flat portions 121a parallel to each other are formed, and are finished smoothly. The flat portion 121a is in close contact with the flat portions 11a on both sides of the positioning hole 11 in the minor diameter direction.

1 and 2, positioning pins 21 project downward in the vicinity of the four corners of the upper divided mold 20 corresponding to the center of the positioning hole 11 of the lower divided mold 10, respectively. Have been. The outer diameter of the positioning pin 21 is substantially the same as the inner diameter of the inner peripheral hole 124 of the bush 12, and the tip (lower end) 21a is formed in a spherical or tapered shape.

The plane portion 11 of the positioning hole 11
a is a straight line L from the flat portion 121 a of the bush 12.
Direction, the length of which is
It is appropriately set in consideration of the difference in the amount of thermal expansion that can occur at zero.

According to the above configuration, when the upper and lower split dies 10 and 20 are moved closer to each other to close the dies, the tip 21 a of the positioning pin 21 of the split dies 20 eventually becomes the inner peripheral hole 124 of the bush 12. Is inserted into the upper end opening portion 124a of the second member. At this time, the displacement amount of the bush 12 displaced in the direction of the straight line L in FIG. 5 together with the positioning holes 11 by the thermal expansion of the lower split mold 10 and the displacement of the bush 12 in the linear L direction by the thermal expansion of the upper split mold 20. Positioning pin 2
In the case where a slight displacement between the axis of the positioning pin 21 and the axis of the bush 12 occurs due to the difference in the amount of displacement of 1, the spherical or tapered tip 21 a of the positioning pin 21 Upper end opening 12 of inner peripheral hole 124
4a, the contact pressure between the outer peripheral surface of the positioning pin 21 and the inner peripheral surface of the bush 12 is unevenly distributed.
The bush 12 moves in the positioning hole 11 in the direction of the straight line L to a position concentric with the positioning pin 21, and is automatically aligned. For this reason, the positioning pin 21 is inserted smoothly without causing “galling” with the inner peripheral surface of the bush 12.

Also, the inner surface of the positioning hole 11 and the bush 1
2 is in contact with the flat portions 11a and 121a, so that the contact surface pressure is significantly lower than in the case of line contact. Effectively suppressed.

In the closed state of the split dies 10 and 20, that is, with the positioning pins 21 fitted in the bushes 12 in the positioning holes 11, for example, the split dies 10 and 2
When a load is applied so as to relatively displace 0 in the direction indicated by the arrow X in FIG. 5, the positioning holes 1 in the direction orthogonal to the X direction, ie, the upper right and lower left in FIG.
Since the bush 12 in 1 cannot move in the X direction, the split dies 10 and 20 are not relatively displaced from each other. This is the same for loads in all directions other than the X direction. Therefore, the positioning function is not impaired by making the positioning hole 11 long and the bush 12 movable.

The present invention is not construed as being limited to the illustrated embodiment. For example, in the above-described embodiment, the positioning holes 11 and the positioning pins 21 are provided in the vicinity of the four corners (four places) of the split dies 10 and 20, but the positions and numbers thereof are particularly three or more in the vicinity of the outer periphery of the dies. Not specified. Further, the positioning hole 11 and the bush 12 may have a shape that slides between flat surfaces, and the flange portions 122 and 1 may be used.
The shape of 23, the shape of both ends of the positioning hole 11 in the longitudinal direction, and the like are not particularly limited to those shown in the drawings. Further, chamfering the upper end opening 124a of the inner peripheral hole 124 of the bush 12 is also preferable as a means for further facilitating the insertion of the positioning pin 21 and the self-aligning operation.

[0018]

According to the present invention, the following effects are realized. (1) Since the bush fitted with the positioning pin can move in a straight line passing through the center of the mold, the displacement between the positioning pin and the bush due to the difference in the amount of thermal expansion of the split mold is automatically eliminated when the mold is closed. In addition, "galling" of the positioning pin does not occur. (2) Since the bush and the positioning hole are in contact with each other on a plane parallel to a straight line passing through the center of the mold, wear due to mutual sliding of the two is suppressed, and a good positioning function is maintained for a long period of time. . (3) Due to the reasons (1) and (2), the split molds are positioned with high accuracy, so that a high quality molded product can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part showing a preferred embodiment of a mold positioning structure according to the present invention.

FIG. 2 is a schematic perspective view showing the embodiment.

FIG. 3 is a schematic sectional view showing a fitting state of a positioning hole and a bush in the embodiment.

4A and 4B show a fitting state of a positioning hole and a bush in the embodiment, wherein FIG. 4A is a cross-sectional view taken along the line AA in FIG. 3, and FIG. 4B is a line BB in FIG. It is sectional drawing cut | disconnected in the position.

FIG. 5 is a schematic plan view of a lower split mold showing the embodiment.

FIG. 6 is a schematic plan view showing a mold positioning structure according to the related art.

DESCRIPTION OF SYMBOLS 10 Lower split mold 11 Positioning hole 11a Flat part 12 Bush 121 Tubular part 121a Flat part 122,123 Flange part 124 Inner peripheral hole 124a Upper end opening 20 Upper split type 21 Positioning pin 21a Tip part

Claims (2)

[Claims] 1. A mold comprising a plurality of split dies (10, 20) arranged to face each other and opposed to each other, wherein one of the split dies (10) is opened at three or more places and passes through a straight line (O). An opening-shaped positioning hole (11) extending long in the L) direction; a bush (12) slidably fitted in the positioning hole (11) in the longitudinal direction; and the other split mold (20). The bush (1) is provided in the mold closing direction so as to correspond substantially to the center of the positioning hole (11).
And a positioning pin (21) that can be inserted into the inner peripheral hole (121b) in a close fitting state. 2. The bush (12) and the positioning hole (11) according to claim 1, wherein the bush (12) and the positioning hole (11) are parallel to a straight line (L) passing through the mold center (O).
1a) A positioning structure of a mold, wherein the positioning structure is formed by contacting each other.