JPH08216161A - Mold apparatus for molding resin - Google Patents

Abstract

PURPOSE: To enhance cooling capacity and to obtain a molded product having good dimensional accuracy by supporting a rotary core insert mold having in undulated stripe extending in the direction inclined with respect to an axial line provided to the molding surface composed of a circumferential surface thereof in a freely rotatable manner by a fixing member through a cross roller bearing. CONSTITUTION: In a mold apparatus for molding a resin, a rotary core insert mold 45 having an undulated stripe extending in the direction inclined with respect to an axial line provided to the molding surface composed of the circumferential surface centering around one axial line thereof is supported in a freely rotatable manner by a fixing member 40 through a cross roller bearing 35 so that a plurality of pieces are arranged between inner and outer wheels 35a, 35b so as to be allowed to cross each other at a right angle along a circumferential direction. Since the cross roller bearing 35 can receive loads in all directions, many bearings are not required as is conventional and the single cross roller bearing 35 may be used. Therefore, a rotary core insert mold system can be miniaturized to a large extent and the water pipes 38, 39 of a cooling circuit can be arranged at the position more approaching a cavity 22 as compared with a conventional mold apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding die device for molding the undulating surface of, for example, a helical gear, a bolt or a nut by using a rotary nest mold.

[0002]

2. Description of the Related Art Referring to FIG. 7, a helical gear 1 has a cylindrical outer peripheral surface 2 on which a plurality of tooth portions 5 whose teeth 3 are inclined with respect to an axial direction 4 are arranged. It has a constant pitch along the direction. As a method of removing the resin molded product of the helical gear 1 from the mold, there is a mold device that employs a rotary nesting method of rotating a nest for forming a tooth portion. For example, the mold device shown in FIG. Referring to the figure, 11 is a movable side mold plate, 10 is a fixed side mold plate, 9 is a runner stripper plate, and 8 is a fixed side mounting plate. The movable mold plate 11 is provided with a concave portion on the surface facing the fixed mold plate 10, and the first core block 25 and the second core for forming the movable mold side engraving surface of the cavity 22 are formed. The block 23 and the core pin 24 are accommodated. 27 is an eject pin. 6 is a locate ring, and 7 is a sprue bush.

The fixed mold plate 10 has a cavity 22.
The cavity block 18 for forming the fixed mold side engraving surface and the rotary nesting mold 26 for forming the teeth of the helical gear are housed. The rotary insert die 26 is supported in the radial direction in a rotatable state around the cavity block 18 via the radial roller bearing 17. In addition, the rotary nesting type 26 is used for the first thrust roller bearing 19
Also, it is supported in the axial direction in a relatively rotatable state with respect to the stationary mold plate 10 via the first thrust washer 32. Further, the second thrust roller bearing 16 and the thrust washer 31 are interposed between the rotary insert mold 26 and the upper runner plate 12. Rotary nesting type 26
The axial movement of the thrust roller bearings 16 and 19 and the thrust washers 31 and 32 is restricted in any of the upper and lower directions, and the fixed side mold plate 10 and the runner plate 12 do not hinder the rotation operation. It can be smoothly rotated around the cavity block 18.

After the resin is completely filled in the cavity 22, the water pipes 28, 2 for cooling the inside of the cavity 22.
9 and 30 are embedded in the runner stripper plate 9, the stationary mold plate 10 and the first core block 25, respectively. When molding is performed using the above mold, the molten resin flows from the primary sprue 13 to the runner while the fixed side mounting plate 8, the runner stripper plate 9, the fixed side mold plate 10 and the movable side mold plate 11 are in close mold contact with each other. It is injection-molded into the cavity 22 from the gate 20 through the secondary sprue 15 passing through the cavity block 18 and the runner 14 formed by the stripper 9 and the runner plate 12. Further, when the mold is opened, the rotary nest mold 26 rotates so that the molded product can be released from the mold.

[0005]

In the above-mentioned conventional mold apparatus, in order to rotatably support the rotary nesting die 26, a radial roller bearing which is supported in the radial direction and a pair of thrust roller bearings which are supported in the axial direction are used. There is. Therefore, the rotary nest type 26 is increased in size in order to secure the supported surface by the plurality of roller bearings 16, 17, and 19, and the rotary nest type 26 and the three roller bearings 16, 1 supporting the rotary nest type 26 are provided.
The size of the rotary nesting system including 7, 19 becomes large.

By the way, the water pipes 28 constituting the cooling circuit,
It is preferable from the viewpoint of cooling efficiency that 29 and 30 are basically arranged at positions as close as possible to the cavity 22 in which the product is molded. However, in the above-described conventional mold apparatus having the large-sized rotary nesting system, it is impossible to arrange the water pipe 29 near the product part, particularly in the stationary mold plate 10, and as a result, an efficient cooling circuit cannot be provided. .
Therefore, when the molded product is cooled and solidified, unevenness occurs in the cooling shrinkage of the resin, which adversely affects the dimensional accuracy of the molded product. Therefore, there is a problem that the required accuracy cannot be ensured particularly for a molded product such as a helical gear that requires high accuracy.

The present invention has been made in view of the above problems, and provides a resin molding die apparatus capable of improving a cooling performance through miniaturization of a rotary nesting die and obtaining a molded article with good dimensional accuracy. The purpose is to

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 relates to an undulation extending in a direction inclined with respect to the above-mentioned axis on a molding surface composed of a circumferential surface having one axis as the center. A rotary nesting type having a strip is rotatably supported by a fixed member through a cross roller bearing in which a plurality of rollers are alternately arranged at right angles along the circumferential direction between an inner ring and an outer ring. It is a feature.

According to a second aspect of the present invention, in the resin molding die apparatus according to the first aspect, a plurality of ridges and ridges on the molding surface are provided at predetermined intervals in the circumferential direction. The present invention is characterized by comprising a groove for forming the tooth portion of the helical gear. The invention according to claim 3 is the mold apparatus for resin molding according to claim 1,
The ridges and ridges on the molding surface are characterized by comprising either a spiral groove for thread formation or a ridge for thread groove formation.

[0010]

According to the structure of the invention according to claim 1, the cross roller bearing supporting the rotary nest type receives a radial load, an axial load, a moment load resolved into these loads, and loads in all directions. You can Therefore, it is not necessary to use many roller bearings as in the conventional case, and a single cross roller bearing is sufficient.

According to the second aspect of the present invention, the tooth portion of the helical gear is formed by the recess provided on the molding surface of the rotary nest type. According to the configuration of the invention according to claim 3, the thread or the groove is formed by the concave or convex line of the spiral line provided on the forming surface of the rotary nest type.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resin molding die apparatus according to an embodiment of the present invention (hereinafter simply referred to as a die apparatus) will be described with reference to FIGS. The mold apparatus of this embodiment is for molding the helical gear of FIG. 7 described above. 1 to 3, parts having the same configurations as those of the prior art shown in FIG. 8 are designated by the same reference numerals and the description thereof is omitted.

Referring to FIG. 1, a fixed side mold plate 10 is provided with a concave portion on a surface facing the movable side mold plate 11, and a fixed mold side engraved surface of a cavity 22 is formed in the concave portion. A cavity block 40 serving as a fixing member and a rotary nesting mold 45 that supports the cavity block 40 via a cross roller bearing 35 and forms the tooth portion 5 of the helical gear are housed. .

Referring to FIGS. 4 and 5, in the cross roller bearing 35, a plurality of rollers 36 and 37 are alternately arranged along the circumferential direction between the inner ring 35a and the outer ring 35b. It has a known configuration. Referring to FIG. 2 showing an enlarged main part of FIG. 1, a recess 40a is formed in the lower surface of the cavity block 40, and the rotary nesting mold 45 and the cross roller bearing 35 are formed in the recess 40a. A rotating nesting system is included that includes

A fixed mold side engraving surface 22a of the cavity 22 is formed at the center of the inner upper surface of the recess 40a. Further, the inner upper surface of the recess 40a is the fixed mold side engraving surface 2
An annular pressing member 4 described later in a state of surrounding 2a.
2 and an annular groove 40b for accommodating 2
In the state of enclosing b, an annular step portion 40c for mounting the outer ring 35b of the cross roller bearing 35, and in an encircling state of the annular step portion 40c, an annular member for fastening an annular pressing member 43 described later. Fastening surface 40d
And have.

Referring to FIG. 6 which is a perspective view of the rotary nesting die, the inner peripheral surface of the rotary nesting die 45 is a circumferential surface having the rotation axis m of the rotary nesting die 45 as a center, and a molding surface 45a.
Is composed. On the molding surface 45a, a concave strip 4 as an undulating strip extending in a direction inclined with respect to the rotation axis m.
5G is formed, and the tooth portion 5 of the helical gear 1 is formed by this recess 45G. Further, a step portion 45c is provided on the outer peripheral surface 45b of the rotary nesting mold 45.
Are formed. A bolt 41 (see FIG. 2) for mounting the pressing member 42 is provided on the upper end surface of the rotary nesting mold 45.
The screw holes 45d into which the reference (see) is screwed are formed at equal intervals on the circumference.

Referring to FIG. 5, the inner ring 35a of the cross roller bearing 35 includes a pressing member 42 fixed to the upper surface of the rotary nesting die 45 by a plurality of bolts 41 and the step portion 45c of the rotary nesting die 45. It is fixed to the rotary nesting mold 45 while being sandwiched between them. The pressing member 42 and the plurality of bolts 41 are housed in the annular groove 40b of the cavity block 40.

On the other hand, the outer ring 35b of the cross roller bearing 35 has a holding member 4 fastened to the fastened surface 40d of the cavity block 40 by a plurality of bolts 44.
3 and the annular stepped portion 40c of the cavity block 40 are fixed to the cavity block 40. A water pipe 39 as a cooling pipe is embedded in the cavity block 40 at a position substantially above the bolt 41. Further, the fixed side template 10 has the water pipe 39.
A water pipe 38 is buried at a position substantially above. These water pipes 38 and 39 are arranged at positions much closer to the cavity 22 than the conventional water pipes 28 and 29 of FIG.

When molding is performed using the above mold, the molten resin is the primary sprue when the fixed side mounting plate 8, the runner stripper plate 9, the fixed side mold plate 10 and the movable side mold plate 11 are in close mold contact with each other. Injection molding is performed from the gate 20 to the inside of the cavity 22 through the secondary sprue 15 passing through the cavity block 40 from the runner stripper plate 9 and the runner 14 formed by the fixed-side mold plate 10.

After the resin is completely filled in the cavity 22, it is cooled and solidified by the water pipes 38, 39, 30. As shown in FIG. 3, first, the runner stripper plate 9 and the fixed side mold plate 10 are opened, and the secondary mold plate is opened. The resin in the sprue is the cavity 2
The gate portion of the product P formed in 2 is torn off and the product P is separated from the cavity block 40. At the same time, the mold opening of the fixed mold plate 10 and the movable mold plate is started. When the product P in the cavity 22 is released from the cavity block 40 and the mold opening is started, the product P is released from the core block 23 to
The fixed side template 1 together with the movable side template 11 while being fixed to 25
Although the tooth portion 5 of the product P having a tilt angle with the mold opening direction exerts a force on the rotary nesting mold 45 in the mold opening direction and a direction perpendicular thereto, the rotary nesting mold 45 is moved away from 0. While rotating, it is released from the rotary nesting mold 45. After the product P is completely released from the stationary mold plate 10,
The product P is ejected by the ejector pin 27, released from the core blocks 23 to 25, and taken out.

According to this embodiment, a single cross roller bearing 3 is not required, unlike the conventional one, which requires many roller bearings.
5, the rotary nesting system including the rotary nesting mold 45 and the structure supporting the rotary nesting mold 45 can be significantly downsized. As a result, the water pipes 38 and 3 that form the cooling circuit
The degree of freedom in selecting the arrangement position of 9 is significantly increased, and the water pipe can be arranged at a position closer to the molding cavity 22 as compared with the conventional case. Therefore, the cooling efficiency of the mold after injection and filling is improved during molding, so that uneven shrinkage of the resin in the molded product is eliminated, and the desired dimensional accuracy of the helical gear as the molded product can be secured. It was That is, in the above-described conventional example, the tolerance range of up to about 90 μm had to be allowed as the variation in the dimension of the molded product, but in the present embodiment, the dimensional accuracy within the tolerance range of up to about 30 μm was achieved. It was possible to achieve the accuracy of three times that of the conventional method.

Further, the improvement of the cooling efficiency shortens the molding cycle, and the molding productivity can be remarkably improved. That is, the molding cycle was 50 seconds / cycle in the above-mentioned conventional example, but was 4 in this example.
It was possible to shorten the time to 2 seconds / cycle by about 20%. Further, since a single cross roller bearing 35 is sufficient as the bearing, the manufacturing cost can be reduced by reducing the number of parts.

The present invention is not limited to the above-described embodiment, and for example, the ridges and ridges on the molding surface of the rotary nest type are formed as spiral ridges for thread forming of bolts. It may be present, or may be formed by a ridge for forming the thread groove of the nut. Besides, various modifications can be made within the scope of the present invention.

[0024]

According to the first aspect of the present invention, a single cross roller bearing is not required as many roller bearings as in the prior art, and therefore a rotary nest and a structure for supporting the rotary nest are included. The nesting system can be significantly downsized. As a result, the degree of freedom in selecting the arrangement position of the water pipe forming the cooling circuit is significantly increased, and the water pipe can be arranged at a position closer to the molding cavity as compared with the conventional case. Therefore, the cooling efficiency of the mold after the injection filling is completed at the time of molding is improved, so that the uneven shrinkage of the resin in the molded product is eliminated, and the desired dimensional accuracy of the molded product can be secured. Further, the improvement of the cooling efficiency shortens the molding cycle, and the molding productivity can be improved. Further, since a single cross roller bearing is sufficient, the manufacturing cost can be reduced by reducing the number of parts.

According to the second aspect of the present invention, it is possible to form a helical gear having a high dimensional accuracy, a low manufacturing cost, and an excellent productivity.
According to the third aspect of the invention, it is possible to obtain a mold apparatus that can mold bolts and nuts with high dimensional accuracy, is inexpensive in manufacturing cost, and is excellent in productivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold apparatus according to an embodiment of the present invention in a mold clamped state.

FIG. 2 is an enlarged view of a main part of the mold device of FIG.

FIG. 3 is a cross-sectional view of the mold device in a mold open state.

FIG. 4 is a partially cutaway perspective view of a cross roller bearing.

FIG. 5 is a vertical cross-sectional view of a cross roller bearing.

FIG. 6 is a schematic perspective view of an inner peripheral surface of a rotary nest type.

FIG. 7 is a perspective view of a helical gear.

FIG. 8 is a cross-sectional view of a conventional mold device.

[Explanation of symbols]

 1 Helical gear 5 Teeth 35 Cross roller bearing 35a Inner ring 35b Outer ring 36,37 Rollers 40 Cavity block (fixing member) 45 Rotating nest type 45a Forming surface 45G Recessed line (rotation line) m Rotation axis

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Claims (3)

[Claims] 1. A rotary nesting mold having a ridged ridge extending in a direction inclined with respect to the axis on a molding surface composed of a circumferential surface centering on one axis, and a rotating nest type between the inner ring and the outer ring. A mold device for resin molding, which is rotatably supported by a fixed member via a cross roller bearing in which a plurality of rollers are arranged so as to be alternately orthogonal to each other. 2. The resin molding die apparatus according to claim 1, wherein a plurality of ridges and valleys on the molding surface are provided in a state in which they are spaced apart from each other by a predetermined distance in the circumferential direction. A resin molding die device comprising a recess for molding a tooth portion. 3. The resin molding die apparatus according to claim 1, wherein the ridge of the molding surface comprises one of a spiral concave groove for screw thread molding and a convex groove for screw groove molding. A mold apparatus for resin molding, characterized in that