JP3278197B2 - Inner diameter undercut processing type - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for molding a part having an undercut such as a helicoid screw, a cam groove or a rib on an inner peripheral surface of a cylindrical molded product.

[0002]

2. Description of the Related Art As a mold and a method relating to undercut processing, there is known a mold and a method disclosed in Japanese Patent Publication No. 59-14333 shown in FIGS. 13 and 14 (A view in FIG. 13). That is, the first side sliding member 102 and the second side sliding member 102
The first side sliding member 102 is formed along the slope of the angle α or β provided on the side sliding member 103 and the core rod 101, respectively.
And a second side sliding member 103, which is configured to engage and slide in the grooves 104, 105. Here, in order for the first side sliding member 102 and the second side sliding member 103 not to interfere with each other, a relationship of 2α ≦ β must be satisfied.

[0003]

However, the above prior art has the following problems. That is, the first side sliding member 102 and the second side sliding member 10
Since the relationship between the angles α and β provided on the core rod 3 and the core rod 101 satisfies 2α ≦ β, the thickness near the base (A) of the second side sliding member 103 is easily reduced, and the second side The strength of the partial sliding member 103 tends to be insufficient. In particular, as shown in FIG. 15, when the length L of the molded product increases, the second side sliding member 1
03 also becomes longer, the thickness near the root (part A) becomes thinner,
Especially the strength is insufficient.

[0004] The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a mold capable of undercut processing having sufficient strength.

[0005]

According to the inner diameter undercut processing type of the present invention, a plurality of cores A and C are arranged alternately around a central core, and a core B is superimposed on the core C. The side of the central core where the core A is disposed is a slope, and the core A and the core B have a molded product forming part, and the central core and the core A, the central core and the core C, The core B and the core C are respectively spliced and engaged, and the core A and the core C
Can slide along the side of the central core,
Can slide along the side of the core C, and when the mold is opened, the cores A and B move along the side of the central core,
The core C was configured to move in a direction opposite to that of the core B.

[0006]

According to the inner diameter undercut processing type, when the mold is opened, the relative movement distance between the core C and the core B becomes longer than the relative movement distance between the center core and the core A. Can make the angle of the surface contacting, that is, the thickness of the core B does not become thin.

[0007]

Embodiment 1 FIGS. 1 to 4 show an inner diameter undercut treatment type of this embodiment. FIG. 1 is a side sectional view including an AA 'sectional view of FIG. 2 shows a closed state of an injection molding die made of No. 2; FIG. 2 is a C-view of FIG.
FIG. 4 is a side sectional view including the CC ′ sectional view of FIG. 4 in a state where the mold is opened, and FIG. In addition, since the fixed die 1 uses a generally known injection molding die, detailed description thereof will be omitted.

The movable die 2 is provided with a center core 3, a core A4, a core B5, and a core C6. The center core 3 has a hexagonal cross section perpendicular to the mold opening direction, every other three sides of the six sides are at an angle α to the mold opening direction, and the other three sides are mold opening. Parallel to the direction (parallel plane). And the center core 3 is 9 below the stripper plate B
Are fixed on the stripper plate B 10.
Note that the lower 9 of the stripper plate B and the upper 10 of the stripper plate B are fastened (the stripper plate B
set).

The core C6 is slidable along the parallel plane of the center core 3. In a state where the core C6 and the center core 3 are combined (center core 3 + core C6), the slopes of the angle α and the angle β alternate. It has a shape with. The core C6 is fixed to the movable mounting plate 7 and the core C receiving plate 8. The movable mounting plate 7 and the core C receiving plate 8 are fastened (the movable mounting plate 7 + the core C receiving plate 8).

The core B5 is slidable along the inclined surface of the core C6 at an angle β, and has a molded product forming surface forming an inner peripheral portion of the molded product. The core A4 has an angle α of the central core 3.
It is slidable along a slope and has a molded product forming surface that forms an inner peripheral portion of the molded product. Core A4 and Core B5
Are alternately arranged around the center core 3 + core C6, and the core B5 is arranged so as to overlap the core C6.
The cores A4 and B5 are held by the lower stripper plate 11 and the upper stripper plate 12 so as to be slidable toward the center of the central core 3. The lower stripper plate A lower part 11 and the stripper plate A upper part 12 are fastened (set of stripper plate A). Note that the relationship between the angles α and β is α ≦ β.

Here, the central core 3 and the core A4, the core B5 and the core C6, and the central core 3 and the core C6 are respectively joined by grooves (4a and 3a, 6a and 5a, 6b and 3b). I have. The set of stripper plate A, the set of stripper plate B, and the center core 3 + core C6 are supported by guide pins (not shown), and are movable in the mold opening direction, but cannot be moved in other directions. A gear 13 is rotatably mounted on the stripper plate B 10. A rack A14 is provided on the lower part 11 of the stripper plate A and the upper part 12 of the stripper plate A.
Are fixed so as to mesh with the gear 13.

Fixed type 1 and lower part 11 of stripper plate A
Are provided with retainers 16, respectively, which are connected by a tension link 17. That is, the lower part 11 of the stripper plate A can be pulled by the fixed mold 1.
A stopper 29 is fixed to the movable mounting plate 7 with a screw 30, and the head of the stopper 29 hits the lower part 9 of the stripper plate B, so that the stripper plate B
The amount of separation between the set and the movable-side mounting plate 7 + core C receiving plate 8 is regulated.

Next, the operation of the above-described inner diameter undercut processing type of this embodiment will be described. First, when the mold is opened (the fixed mold 1 and the movable mold 2 are separated), the fixed mold 1 pulls the lower part 11 of the stripper plate A by the pulling link 17. Then, the set of stripper plates A tries to separate from the set of stripper plates B, and the set of stripper plates B tries to separate from the movable mounting plate 7 + core C receiving plate 8. Therefore, rack A14 and rack B15
While rotating gear 13, stripper plate A
Set and stripper plate B set, stripper plate B
The set and the movable-side mounting plate 7 + the core C receiving plate 8 are separated from each other. The amount of separation between the set of stripper plate B and the movable-side mounting plate 7 + core C receiving plate 8 is determined by the stopper 2
9

At this time, the rack A14 and the rack B15
And the gear 13, the amount L ₁ in which the stripper plate group A and stripper plate B group is separated, the amount L ₂ of the movable side mounting plate 7+ core C receiving plate 8 is separated from the stripper plate Group B, L ₁ = L ₂ (see FIG. 3). Accordingly, the core B5 apparently moves in the mold opening direction by a distance twice as long as the core A4. Further, since the angle relationship is α ≦ β, the core B5 moves at least twice the distance of the core A4 toward the center of the center core 3, and the core A4 and the core B5 contract as shown in FIG. be able to.

According to this embodiment, the angle relationship is α ≦ 2.
Even if it is not β, since core A4 and core B5 do not interfere,
The thickness of the base of the core B5 does not become too thin, and the strength is excellent.

[0016]

Embodiment 2 FIGS. 5 and 6 show an inner diameter undercut processing type in this embodiment. FIG. 5 is a side sectional view showing a state in which the mold is closed, and FIG. It is sectional drawing. In addition, except for the gear 13, the rack A14, and the rack B15 in the first embodiment (FIGS. 1 to 4), the first embodiment.
The same components are denoted by the same reference numerals, description thereof will be omitted, and different components will be mainly described.

A screw A1 is attached to the lower part 11 of the stripper plate A.
8 is fixed. On the stripper plate B 10, a screw receiver A19 is rotatably mounted.
When the screw A18 moves in the mold opening direction, the screw receiver A
19 rotates. A gear is provided on the outer periphery of the screw receiver A19. On the stripper plate B 10, a screw B20 is rotatably mounted. A gear is provided on the outer periphery of the screw B20, and a screw receiver A
Meshes with 19 gears. A screw receiver B21 that receives the screw B20 is fixed to the core C receiving plate 8.

As the set of stripper plate A and the set of stripper plate B are separated, the screw receiver A19 rotates and the screw B20 also rotates. At this time, the screw B and the screw receiver B21 are configured so that the rotation of the screw B20 causes the screw receiver B21, that is, the movable-side mounting plate 7 + the core C receiving plate 8 to move in a direction to separate from the stripper plate B set. Further, the amount L ₁ in which the stripper plate group A and stripper plate B group is separated, the relationship between the amount L ₂ of the movable side mounting plate 7+ core C receiving plate 8 is separated from the stripper plate Group B, and the angle of α The angle is appropriately set according to the relationship with β (the angle between α and β is appropriately set according to the relationship between L ₁ and L ₂ ). For example, when α = β, the lead and gear diameter of each screw are set so that L ₁ ≦ L ₂ .

Next, the operation of the above-described inner diameter undercut processing type of this embodiment will be described. First, when the mold is opened, the fixed mold 1 pulls the lower part 11 of the stripper plate A by the pulling link 17, and the set A of the stripper plate and the set B of the stripper plate are separated while the screw A18 rotates the screw receiver A19. The screw B20 is rotated by the rotation of the screw receiver A19. Then, rotation of the screw B20 causes the screw receiver B21, that is, the movable-side mounting plate 7+
The core C receiving plate 8 is separated from the stripper plate B set.

As described above, the set of stripper plate A and the set of stripper plate B are separated by L1, and the set of stripper plate B and the movable side mounting plate 7 + core C
The receiving plate 8 is separated by L2. Thereafter, in the same manner as in the first embodiment, the core A4 and the core B as shown in FIG.
5 can shrink.

According to this embodiment, in addition to the effects of the first embodiment, L and L are set by setting the lead and gear diameter of each of the screws A18, A19, B20 and B21.
It is possible to change the _first and L ₂ relations, it can be appropriately set to a slope of the relationship between the slope and β angle alpha. That is, the degree of freedom in designing the center core 3, the core A4, the core B5, and the core C6 increases.

[0022]

Third Embodiment FIGS. 7 to 10 show an inner diameter undercut processing type according to the present embodiment. FIG. 7 is a side sectional view including a cross section taken along line EE 'of FIG. 8 is an arrow F view of FIG. FIG. 9 is a side sectional view including a sectional view taken along the line GG ′ of FIG. 10 in a state where the mold is opened, and FIG. 10 is an H view of FIG. 9. The first embodiment (FIGS. 1 to 4) and the second embodiment (FIGS. 5 and 6) correspond to the center core 3, the core A4, and the core B.
5, except for the shape of the core C6, other configurations are the same as those of the first or second embodiment. The same portions are denoted by the same reference numerals, and the description thereof will be omitted. explain.

The center core 22 has a shape obtained by shaving three places from a truncated cone in parallel with the mold opening direction. Core C25
Is slidable along a plane parallel to the mold opening direction of the center core 22, and forms a truncated cone in a state where the core C25 and the center core 22 are combined (center core 22 + core C25). The core B24 is slidable along the slope of the core C25.
The core A23 is slidable along the slope of the central core 22. The cores A23 and B24 are alternately arranged around the central core 22 + core C25 alternately,
4 is arranged so as to overlap the core C25. The core A23 and the core B24 are held by the lower stripper plate 11 and the upper stripper plate 12 so as to be slidable in the center direction of the central core 22. Here, the central core 22
And core A23, core B24 and core C25, central core 22
And the cores C25 are each joined by a groove.

The operation of the above-described inner diameter undercut processing type of the present embodiment is the same as that of the above-described first or second embodiment, so that the description thereof will be omitted. According to this embodiment, the same effects as those of the first or second embodiment can be obtained, and the thickness of the base of the core B24 can be further increased.

[0025]

Embodiment 4 FIGS. 11 and 12 show an inner diameter undercut processing type in this embodiment. FIG. 11 is a side sectional view in a state where the mold is closed, and FIG. 12 is a side sectional view in a state where the mold is opened. FIG. The same parts as those in the first embodiment (FIGS. 1 to 4), the second embodiment (FIGS. 5 and 6), and the third embodiment (FIGS. 7 to 10) are denoted by the same reference numerals, and description thereof will be omitted. Then, the different parts will be mainly described.

The sliding surface between the center core 25 and the core C28 is inclined in the opposite direction to the sliding surface between the core B27 and the core C28. The core C28 is attached to the movable mounting plate 7 and the core C receiving plate 8 so as to be movable toward the center of the center core 25.

The operation of the above-described inner diameter undercut processing mold of this embodiment will be described. When the mold is opened and the set of stopper plates B is separated from the movable mounting plate 7 and the core C receiving plate 8, the core C28 becomes the inclined surface of the central core 25. Is moved toward the center of the central core 25 while sliding. Other operations are the same as those in the above-described first, second, and third embodiments, and a description thereof will be omitted. According to this embodiment, the thickness of the base of the core B27 can be further increased, and the strength is excellent.

In each of the above-described embodiments, the case where three cores (core A, core B, and core C) are provided has been described. However, the present invention is not limited to this.
One or four can be used as needed. Further, the present invention is not limited to a cylindrical molded product, and can be used for a molded product having a polygonal prism shape such as a quadrangular prism.

[0029]

As described above, according to the inner diameter undercut treatment type of the present invention, it is possible to obtain a mold with sufficient strength and capable of undercut treatment.

[Brief description of the drawings]

FIG. 1 is a side sectional view including an AA ′ sectional view of FIG. 2 of an inner diameter undercut processing type according to a first embodiment of the present invention.

FIG. 2 is a diagram viewed from an arrow C in FIG.

FIG. 3 is a cross-sectional view taken along the line CC ′ of FIG. 4 with the mold of FIG. 1 opened;
It is a side sectional view including a sectional view.

FIG. 4 is a view taken in the direction of arrow D in FIG. 3;

FIG. 5 is a side sectional view of an inner diameter undercut processing type according to a second embodiment of the present invention.

FIG. 6 is a side sectional view in a state where the mold of FIG. 5 is opened.

FIG. 7 is a side sectional view including an EE ′ sectional view of FIG. 8 of an inner diameter undercut processing type according to a third embodiment of the present invention;

FIG. 8 is a view as viewed in the direction of arrows F in FIG. 7;

FIG. 9 is a sectional view taken along line G- in FIG.
It is side sectional drawing including G 'sectional drawing.

FIG. 10 is an H view of FIG. 9;

FIG. 11 is a side sectional view of an inner diameter undercut processing type according to a fourth embodiment of the present invention.

FIG. 12 is a side sectional view in a state where the mold of FIG. 11 is opened.

FIG. 13 is a side sectional view of a conventional inner diameter undercut processing type.

FIG. 14 is a diagram viewed from the arrow A in FIG. 13;

FIG. 15 is a side sectional view of a conventional inner diameter undercut processing type.

FIG. 16 is a diagram viewed from an arrow B in FIG. 15;

[Explanation of symbols]

 Reference Signs List 1 fixed type 2 movable type 3 center core 4 core A 5 core B 6 core C 3a provided groove 3b provided groove 5a provided groove 4a provided 6a provided 6b provided 13 gear 14 rack A 15 rack B

──────────────────────────────────────────────────の Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 33/44 B29C 39/34 B29C 45/44

Claims (1)

(57) [Claims] 1. A plurality of cores A and C are arranged alternately around a central core, a core B is arranged so as to overlap the core C, and the core A of the central core is arranged. The core A and the core B have a molded product forming part, and the central core and the core A, the central core and the core C, and the core B and the core C are respectively spliced and engaged. A and core C
Can slide along the side of the central core,
Can slide along the side of the core C, and when the mold is opened, the cores A and B move along the side of the central core,
The core C moves in a direction opposite to that of the core B.