JP3296844B2 - Mold for molding cylindrical objects with inner diameter undercut - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical member which must not have a taper like an optical lens barrel, and which has an undercut portion such as a lateral hole or a screw groove provided on an inner peripheral surface thereof. The present invention relates to a mold for forming a cylindrical object having an inner diameter undercut.

[0002]

2. Description of the Related Art Heretofore, as a molding die for molding a cylindrical object having an undercut portion on an inner peripheral surface, Japanese Patent Publication No. Sho 59-1 has been known.
No. 4333. The above mold is shown in FIG.
As shown in FIGS. 6 and 17, a frustum-shaped core pin 1 having a plurality of dovetail grooves formed in an axial direction of an outer peripheral surface is provided, and two types of divided slide cores forming an inner peripheral portion 2a of a molded product 2 are provided. 3 and 4 are alternately arranged on the outer periphery of the core pin 1 by dovetail engagement. The slide cores 3 and 4 are provided so as to be guided along the outer peripheral surface of the core pin 1 by dovetail grooves. After the molded product 2 is formed, the core pins 1 are moved in the axial direction so as to be pulled out from the slide cores 3 and 4. As a result, the slide cores 3 and 4 move in the diameter direction of the shaft, and the undercut portion of the molded product is removed.

[0003]

However, in the above-mentioned conventional mold, all the dovetail grooves of the core pin 1 which are dovetailedly engaged with the slide cores 3 and 4 are required to be aligned when machining. As the number of slide cores 3 and 4 increased, the number of processing steps increased. Since the slide cores 3 and 4 serve as a molding surface of the inner peripheral portion 2a of the molded product 2, this alignment operation is an indispensable process for preventing burrs and dimensional accuracy. Because of the quenching, there is a problem that an enormous amount of time is required for the aligning operation, and the cost of the mold is increased. In addition, since the dovetail grooves are used to bring the slide cores 3 and 4 into close contact with the core pins 1, when the molded product 2 having a small inner diameter and having an undercut is formed, the dovetail grooves are very small, which makes processing difficult. There was a problem. Further, depending on the size of the inner peripheral portion 2a of the molded product 2, there is a case where there is no space for forming the dovetail groove. Even if the dovetail groove can be formed, the dovetail groove becomes small. In addition, there is a problem that the processing takes an enormous amount of time, and the production cost of the mold increases. The present invention has been made in view of the above-described problems of the related art, and it is possible to obtain a molded product having a high finishing accuracy and a good appearance with less burrs, and having a low-cost inner diameter undercut without using a dovetail groove. An object of the present invention is to provide a mold for molding a cylindrical object.

[0004]

In order to achieve the above-mentioned object, a cylindrical mold having an inner diameter undercut according to the present invention has a conical outer surface as shown in FIGS. The first slide core 12 having a small outer circular arc surface and the second slide core 13 having a large outer circular arc surface forming the inner wall of the cavity every other outer surface of the core pin 11 are connected to the core pin 11.
Are disposed so as to be movable relative to the core pin 11 in the axial direction and are provided so as to be movable inward, and the portions below the portions 12a, 13a forming the cavity are closer to the first slide core 12 than the second slide core 13. Form a long,
And a taper 1 on each side surface of the end portion of the lower portion.
2b and 13b, and a sleeve 14 provided on the inner surface with a taper 14a in contact with the tapers 12b and 13b is provided so as to be movable in the axial direction of the core pin 11.

[0005]

According to the above construction, the core pin 11 moves the first and second slide cores 12 and 13 outwardly to bring the first and second slide cores 12 and 13 into close contact with each other (FIG. 4).
5). After injecting and cooling the molten resin, the mold is opened, the core pin 11 is moved downward, and the sleeve 14 is moved upward. At this time, the taper 12b of the first slide core 12
The portion slides on the tapered portion 14a of the sleeve 14, and each first slide core 12 moves inward, and the cavity molding surface 12a of each first slide core 12 separates from the inner diameter surface of the molded product (see FIGS. 6 and 7). Thereafter, when the sleeve 14 further rises, the taper 13b of the first slide core 13 slides on the taper 14a of the sleeve 14, and each second slide core 1
3, the cavity molding surface 13a of each second slide core 13 is separated from the inner diameter surface of the molded product (FIGS. 8, 9).
reference).

[0006]

[Embodiment 1] FIG. 10 is a longitudinal sectional view showing a movable mold portion of a molding die according to Embodiment 1 of the present invention. In the figure, 20
Is a core pin with a conical outer surface from the center to the tip,
The base end is fixed to the upper and lower core pin mounting plates 21 and 22 and is provided movably in the axial direction (vertical direction in the figure) together with the upper and lower core pin mounting plates 21 and 22. A small outer circular arc surface around the conical outer surface of the core pin 20 is formed such that the inner surface is formed at the same inclination as the outer surface of the conical shape, and the inner wall surface of the cavity is formed on the outer surface of the tip (hereinafter referred to as a cavity forming surface). First slide core 2 having
The second slide cores 24 each having a large outer peripheral arc surface are arranged alternately with each other and are movably provided in a direction orthogonal to the axis of the core pin 20. First
Cavity forming surface 23 of second slide cores 23 and 24
A flange 23b, 24b is formed at the same position from the tip on the lower outer side surface of each of the flanges 23b, 2a by the movable side mold plates 25a, 25b, 25c laminated in three layers.
4b is slidably held in the above direction. Tsuba 23
In a portion below b and 24b, the first slide core 23 is formed to be longer than the second slide core 24, and tapered ends 23c and 24c having the same inclination angle are provided on the outer end surface of the first slide core 23, respectively.

Below the first and second slide cores 23 and 24, a sleeve 26 is provided movably in the axial direction of the core pin 20 with the sleeve 26 inserted through the core pin 20. The distal end of an ejector rod 27 is connected to the lower end of the sleeve 26, and the base end of the ejector rod 27 is located between the upper and lower movable ejector rod mounting plates disposed below the core pin mounting plate lower 22 and between the lower and upper 28, 29. It is fixed to. On the inner surface of the sleeve 26, the tapers 23c, 24
A taper 26a having the same inclination angle as the tapers 23c and 24c is provided so as to be in contact with the taper 23c.

A template 30 is arranged between the sleeve 26 and the core pin mounting plate 23 so as to be vertically movable. Around the sleeve 26, a spacer block 31 attached to the movable mold plate 25c is arranged. Stop pins 32 are attached to the spacer block 31 so as to penetrate the upper and lower core plates 21 and 22 and the template 30. Through hole 3 of stop pin 32 provided in template 30
0a, a spring 3 is provided so as to wind the stop pin 32.
3 are provided to urge the upper and lower core pins 21 and 22 in the direction away from the spacer block 31.

Next, the operation of the molding die of this embodiment will be described with reference to FIG.
This will be described with reference to FIG. After the molten resin is injected and cooled, the movable side mold part is lowered to open the mold, and the core pin 20 is lowered by lowering the upper and lower core pin mounting plates 21 and 22 together with the template 30 by the spring 33 mounted by compression. Then, the conical outer surface of the core pin 20 and the inner surfaces of the first and second slide cores 23 and 24 are released (FIG. 11). Next, the ejector rod 27 is moved upward, and the sleeve 26 is pushed up. At this time, the taper 23 of the first slide core 23
The portion c slides on the tapered portion 26a of the sleeve 26, the first slide core 23 moves inward, and releases the cavity molding surfaces 23a of the first slide cores 23 from the inner diameter surface of the molded product M (see FIG. 12). .

Further, when the sleeve 26 is pushed up, the tapered portion 24c of the second slide core 24 comes into contact with the tapered portion 26a of the sleeve 26. Thereafter, the tapered portion 24c slides on the tapered portion 26a, and the second slide core 24 is moved inward. Then, the cavity molding surface 24a of each second slide core 24 is released from the inner diameter surface of the molded product M (see FIG. 13). As described above, the cavity molding surfaces 23a and 24a of the first and second slide cores 23 and 24 are completely separated from the undercut formed on the entire inner circumference of the molded product M, and the molded product M can be taken out.

According to the present embodiment, the first and second slide cores 23 and 24 which are opened outward by the core pin 20 and are in close contact with each other are moved inward by the sleeve 26, respectively. A dovetail groove and a dove for dovetail engagement between the core pin 20 and the first and second slide cores 23 and 24 become unnecessary. Therefore, the space for forming the dovetail groove and the dovetail becomes unnecessary, so that the core pin 20 and the first and second slide cores 23 and 24 can be reduced, and a small product having an undercut in the inner diameter can be formed. Further, the molding of the core pin 20 and the first and second slide cores 2324 is facilitated, and the production cost of the molding die is reduced. Also, the first and second slide cores 2 forming the cavity
In the removal of the molded product M compared with the conventional example, the components 3 and 24 do not require the clearance or the like of each part, so that they can adhere to each other and maintain the mutual positional relationship with high accuracy. Good appearance M with little appearance
Can be obtained.

[0012]

Embodiment 2 FIG. 14 is a sectional view showing a movable mold portion of a molding die according to Embodiment 2 of the present invention. The sleeve 26 of the present embodiment is arranged such that the base end is fixed between the upper sleeve mounting plate 35 and the lower sleeve mounting plate 36. The upper and lower sleeve mounting plates 35 and 36 are penetrated by the core pin 20, and the upper core pin mounting plate 21 and the movable side mounting plate 25c.
Are provided movably in the up-down direction.

Between the upper core pin mounting plate 21 and the lower sleeve mounting plate 36, an upper cam mounting plate 37 and a lower cam mounting plate 38 penetrated by the core pins 20 are provided so as to be vertically movable. A notch 37a is formed on a side surface of the upper cam mounting plate 37, and a cam 39 is provided in the notch 37a.
Is arranged. The cam 39 has a pin 4
The cam 39 is attached to the upper cam mounting plate 37 so as to be freely rotatable in the vertical direction, and the lower surface of the lower sleeve mounting plate 36 can be pushed upward by one end 39a of the cam 39.
Note that the cam 39 has a short upper cam mounting plate 37,
It may be attached to a projection provided on the lower portion 38 of the cam attachment plate.

A spacer block 41 is arranged around the upper and lower sleeves 35 and 36 and the upper and lower cams 37 and 38 of the cam mounting plate. A template 42 is disposed between the spacer block 41 and the movable template 25c, and the spacer block 41 and the template 42 are provided so as to be able to move up and down separately from the movable template 25c. A notch 41 a into which the other end 39 b of the cam 39 is inserted is formed on a side surface of the spacer block 41. Further, below the sleeve mounting plate 36, the movable mold plate 25 is moved from the fixed mold.
a, 25b, 25c, a lower end portion of a stop pin 43 provided through the upper and lower portions 35, 36 of the mold plate 42 and the sleeve mounting plate, and a large-diameter lower end portion of the stop pin 43 and a sleeve when the mold is opened. The lower surface of the lower mounting plate 36 is locked,
The upper and lower portions 35 and 36 of the sleeve mounting plate are prevented from lowering by a certain amount or more. The stop pin 43 is provided with a spring 44 that urges the upper and lower sleeves 35 and 36 in a direction away from the template 42 so as to be wound. In addition, the core pin 20, the first and second slide cores 22, 2
3, the configuration of the sleeve 26 and the like are the same as those in the first embodiment, and the description thereof is omitted.

Next, the operation of the molding die of this embodiment will be described. After injecting and cooling the molten resin, the movable mold section is lowered to open the mold. When the movable mold section is lowered by a predetermined amount, the movable mold plates 25a and 25
b, 25c, the lowering of the sleeve mounting plate, the lower 35, 36 and the lowering of the cam mounting plate, 37, 38, are stopped.
The upper and lower core pins 21 and 22, the spacer block 41 and the mold 42 are continuously lowered. As a result, the core pin 20 is connected to the first and second slide cores 23 and 24.
It moves downward so as to be pulled out from the inside, and
And the inner surfaces of the first and second slide cores 23 and 24 are separated from each other.

Further, upper and lower core pin mounting plates 21 and 21
2. The spacer block 41 or the like is lowered, and the upper surface of the notch 41a of the spacer block 41 is
When the cam 39 rotates downward about the pin 40, the one end 39a of the cam 39 pushes the upper and lower sleeves 35 and 36 upward. As a result, the sleeve 26 moves upward, as in the first embodiment, first moving the first slide core 23 inward, and then moving the second slide core 24
Move inward. As described above, molded products (not shown)
First and second from the undercut formed around the entire inner diameter of
Cavity forming surfaces 23a, 2 of slide cores 23, 24
4a is completely separated, and the molded product can be taken out.

According to this embodiment, the same effect as in the first embodiment can be obtained, and the molded product M is released by utilizing a mold opening force in a series of mold opening operations. be able to.

[0018]

Third Embodiment FIG. 15 is a sectional view showing a movable mold portion of a molding die according to a third embodiment of the present invention. The sleeve 26 of this embodiment is mounted on a receiving plate 45. Receiving plate 45
Are mounted on the core pin mounting plate 21 and the core pin 2
0 is penetrated. The spacer block 31 is provided between the receiving plate 45 and the movable mold plate 25c,
6 can be moved upward. Below the receiving plate 45, the first ejector rod 4 that pushes up the receiving plate 45
6 is disposed through the upper and lower core pin mounting plates 21 and 22, and the base end of the first ejector rod 46 is disposed at a position below the spacer block 31 and is movable vertically.
The ejector rod is fixed between the upper and lower 47, 48 on the mounting plate. Further, below the sleeve 26, a sleeve 2 is provided.
A second ejector rod 49 for pushing up the second ejector rod 6 is disposed so as to penetrate the upper and lower core pins 21 and 22 and the receiving plate 45. On board, below 50, 51
It is fixed in between. In addition, since the configuration of the core pin 20, the first and second slide cores 23 and 24, the sleeve 26, and the like are the same as those in the first embodiment, description thereof will be omitted.

Next, the operation of the molding die of this embodiment will be described. After injecting and cooling the molten resin, the fixed mold section (not shown) and the movable mold section are separated from each other and the mold is opened.
The ejector rod 46 is moved upward to push up the receiving plate 45, the first and second slides 23 and 24 and the like are moved upward, and the core pin 20 is moved to the first and second slide cores 23 and 24.
And the inner surfaces of the first and second slide cores 23 and 24 are separated from each other. next,
The second ejector rod 49 is moved upward to
6, the first slide core 23 is first moved inward, and then the second slide core 2 is moved in the same manner as in the first embodiment.
Move 4 inward. As described above, molded products (not shown)
First and second from the undercuts formed around the entire inner diameter of
The cavity molding surfaces 23a and 24a of the slide core are completely separated, and the molded product can be taken out. According to this embodiment, the same effect as that of the first embodiment can be obtained.

[0020]

As described above, according to the present invention, the process of dovetail-engaging the core pin and the first and second slide cores is not required, so that the production of the core pin and both slide cores is facilitated. The production cost of the mold can be reduced. In addition, the first and second slide cores that form the cavities do not require clearance or the like for each component in taking out the product as compared with the conventional example, so that they are closely attached to each other,
Since the mutual positional relationship can be maintained with high precision, it is possible to obtain a molded product with high finish precision and good appearance with few burrs.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a main part of a mold for molding a cylindrical object having an inner diameter undercut according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an exploded perspective view showing a main part of a molding die of the present invention.

FIG. 4 is a cross-sectional view showing a state during injection molding of a molding die of the present invention.

FIG. 5 is a plan view of FIG. 4;

FIG. 6 is a cross-sectional view of the molding die of the present invention when the first slide core is released.

FIG. 7 is a plan view of FIG. 6;

FIG. 8 is a cross-sectional view of the molding die of the present invention when the second slide core is released.

FIG. 9 is a plan view of FIG. 8;

FIG. 10 is a sectional view showing a molding die according to Example 1 of the present invention.

FIG. 11 is a sectional view showing a state in which a core pin is lowered in a molding die according to the first embodiment of the present invention.

FIG. 12 is a cross-sectional view of the molding die according to the first embodiment of the present invention when the first slide core is released.

FIG. 13 is a cross-sectional view of the molding die according to the first embodiment of the present invention when the second slide core is released from the mold.

FIG. 14 is a sectional view showing a molding die according to a second embodiment of the present invention.

FIG. 15 is a sectional view showing a molding die according to a third embodiment of the present invention.

FIG. 16 is a plan view showing a main part of a conventional molding die.

FIG. 17 is a sectional view showing a main part of a conventional molding die.

[Explanation of symbols]

 11, 20 Core pin 12, 23 First slide core 12a, 23a Cavity forming surface 12b, 23c Taper surface 13, 24 Second slide core 13a, 24a Cavity forming surface 13b, 24c Taper 14, 26 Sleeve 14a, 26a Taper

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 33/00-33/76 B29C 39/26-39/36 B29C 41/38-41/44 B29C 43 / 36-43/42 B29C 43/50 B29C 45/26-45/44 B29C 49/48-49/56 B29C 49/70 B29C 51/30-51/40 B29C 51/44

Claims (1)

(57) [Claims] 1. A first slide core having a small outer circular arc surface and a second slide core having a large outer circular arc surface forming an inner wall of a cavity every other outer surface of a core pin having a conical outer surface in the axial direction of the core pin. The first slide core is formed so as to be relatively movable with respect to the core pin and is provided so as to be movable inward, the lower part of the first slide core is formed longer than the second slide core, and the lower part of the lower part of the cavity is formed. A molding die for a cylindrical object having an inner diameter undercut, wherein a taper is provided on each of the side surfaces of the end portion, and a sleeve provided on the inner surface with a taper in contact with the taper is movably provided in the axial direction of the core pin. Type.