JPH05147082A - Mold for bore undercut processing - Google Patents

Abstract

PURPOSE:To provide a mold for bore undercut processing mold of a relatively small size capable of keeping a high accuracy of a molded piece with a superior durability. CONSTITUTION:A first ejector core 20 having a cross section of a substantially trapezoid and a second ejector core 21 having a cross section of a substantially arc are alternately provided on the peripheral surface of a center core 19. The first ejector core 20 is connected to a first inclined rod inclined through an angle alpha2 to a mold open direction. The first inclined rod is provided movably at the angle alpha2. The second ejector core 21 is connected to a second inclined rod 26 inclined through an angle beta2 to a mold open direction. The second inclined rod 26 is provided so as to move at the angle beta2 after moving in a mold open direction. In this manner, firstly a molded piece is separated from the first ejector core 20 and next separated from the second ejector core 21.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a molding die for undercutting and a molding method using this type of molding die are disclosed, for example, in Japanese Patent Publication No. 59-14333 and Japanese Patent Laid-Open No. 62-156918.
It is disclosed in Japanese Patent Publication No. 1-46296. As shown in FIGS. 9 and 10, the molding die described in Japanese Patent Publication No. 59-14333 has, on the outer peripheral surface of the core rod 60, slopes having an angle α and an angle β respectively in the axial direction, which are alternately arranged in the circumferential direction. The first side sliding member 61 and the second side sliding member 61 and the second side sliding member 62 are alternately arranged in contact with the inclined surfaces of the angles α and β, respectively. The member 62 is engaged with the dovetail grooves 63 and 64 formed on each slope, and is provided slidably along the slope in the axial direction of the core rod 60. Then, the belt-shaped portions 65 and 66 provided on the outer sides of the first side sliding member 61 and the second side sliding member 62 are directly pushed up to the first side.
The side sliding member 61 and the second side sliding member 62 are slid along the respective slopes, and the first and second side sliding members 6
1, 62 can be moved inward in the radial direction of the core rod 60 to the mold open state.

A molding die used in the molding method described in Japanese Patent Laid-Open No. 62-156918 has a first side sliding member and a second side sliding member.
Except for the point that the side sliding member and the side sliding member are respectively slid through the connecting rod by utilizing the ejecting force of the molding machine, the above Japanese Patent Publication No.
It has the same structure as the molding die of 9-14333. Further, in the molding die used in the molding method described in Japanese Patent Publication No. 1-46296, the inner peripheral wall of the cavity is formed by a split die, and the split die can be moved inward by an angular pin.

[0004]

However, the Japanese Patent Publication No. 59-
In the molding die described in Japanese Patent No. 14333, the first side sliding member 61 and the second side sliding member 62 move inward at the same time, so the first and second side sliding members 61, 6
There is a problem that the gap when the 2 moves inward is small, the two interfere with each other and are easily bite, and the mold is easily damaged. Further, the slopes of the angles α and β or the dovetail grooves 63 and 64 are the first,
When the second side sliding members 61, 62 are worn by sliding, the positional accuracy of the first and second side sliding members 61, 62, that is, the accuracy of the molded product, is deteriorated.
Further, the molding die described in JP-A-62-156918 also has the same problems as described above. On the other hand, the mold described in Japanese Patent Publication No. 1-46296 requires a space for the angular pin around the cavity. For this reason, when it is attempted to form the outer periphery of the molded product by the slide insert, there is a problem that a space is further required for the angular pin of the slide insert on the outer periphery, and the mold becomes large. The present invention has been made in view of the above-mentioned conventional problems, and is excellent in durability that is unlikely to be damaged, has high accuracy of molded articles, and can provide an inner diameter undercut processing mold that does not become relatively large. To aim.

[0005]

To achieve the above object, the inner diameter undercut mold of the present invention has a first extruded core having a substantially trapezoidal cross section and a substantially arcuate cross section. A plurality of second and second projecting cores are alternately arranged around the central core, and the first projecting cores are connected to the first tilting rod provided at an angle α ₂ with respect to the mold opening direction. At the same time, the _second tilted rod holds the first tilted rod slidably in the angle α ₂ direction, while the second protruding core is tilted by the angle β ₂ with respect to the mold opening direction. In addition to the connection, the second inclined rod is held slidably in the mold opening direction and the angle β ₂ direction. Further, the first protruding core is in contact with the inclined surface of the central core provided with an inclination of an angle α ₁ with respect to the mold opening direction, and the angle α ₁ has a relationship of α ₁ ≧ α _2. good.

[0006]

In the inner diameter undercut processing type configured as described above, the first protruding core and the first inclined rod move along the inclination of the first inclined rod, and the second protruding core and The second tilted rod first moves in the mold opening direction and then moves along the tilt of the second tilted rod, and the first protruding core and the second protruding core are released from the molded product. By setting α ₁ ≧ α ₂ , the first protruding core and the first inclined rod move at the angle α ₂ and do not slide on the surface at the angle α ₁ .

[0007]

Embodiment 1 FIGS. 1 to 5 show Embodiment 1 of an inner diameter undercut processing type (hereinafter referred to as a processing type) according to the present invention. FIG. 1 is a cross section of the processing type, FIG. 2 and FIG. Is a cross-sectional view of the processing die showing the state of the molded product at the time of releasing the mold, FIG. 4 is a plan view of the central core and the first and second protruding cores seen from the direction of arrow A in FIG. 1, and FIG. FIG. 4 is a plan view of the central core and the first and second protruding cores as seen from the direction of arrow B in FIG. 3. The processing mold 1 of this embodiment is composed of a fixed mold part 2 and a movable mold part 3 as in the case of a general injection molding mold, and both mold parts 2 and 3 are parting surfaces (P, L) is fixedly joined and can be separated.

In the fixed mold section 2, a fixed side mounting plate 4, a fixed side stripper plate 5 and a fixed side mold plate 6 are arranged in a stacked state from the injection molding machine (not shown) side.
A locating ring 7 is attached to the fixed side mounting plate 4, and a sprue bush 8 communicating with the locating ring 7 penetrates the fixed side template 4 and the fixed side stripper plate 5 and a movable metal via a runner 9 and a gate 10. Cavity 11 of mold 3
Is in communication with. An accommodating portion 13 that accommodates the multi-divided slide inserts 12 forming the outer peripheral wall of the cavity 11 is formed in the fixed-side template 6, and the angular pins 14 protruding from the accommodating part 13 are the same number as the slide inserts 12. However, they are integrally fixed by a fastening member (for example, a bolt, the same applies hereinafter) not shown.

The movable mold part 3 includes a movable side mold plate 15, a movable side receiving plate 16, a spacer block 17, and a movable side mounting plate 1.
8 are arranged. A central core 19 is integrally fixed to the movable receiving plate 16 by a fastening member (not shown) in a state of protruding in the direction of the fixed mold portion 2. Central core 19
Has a hexagonal cross section as shown in FIG.
Around the central core 19 is in contact with each side and slidably
The protruding cores 20 and the second protruding cores 21 are alternately arranged. Each side of the central core 19 on which the first protruding core 20 slides is formed as an inclined surface at an angle α ₁ with respect to the mold opening direction (the horizontal direction in FIGS. 1 to 3),
Each side on which the second protruding core 21 slides is formed on a slope having an angle β ₁ with respect to the mold opening direction, and the first protruding core 20 and the second protruding core 21 are formed.
Are respectively arranged at angles of α ₁ and β ₁ with respect to the mold flat opening direction.

The first extruded core 20 has a substantially trapezoidal cross-sectional shape, and the second extruded core 21 has a substantially arcuate cross-sectional shape. Each second protruding core 21
A rectangular guide 22 is integrally formed over the entire length of the second protruding core 21 on the string (the surface in contact with the central core 19) of each of the central cores 19 in contact with the second protruding core 21. A rectangular guide groove 23 corresponding to the guide 22 is formed in the piece over the entire area in the longitudinal direction. A helicoid 2 that forms an undercut portion at the outer peripheral tip portions of the first protruding core 20 and the second protruding core 21.
4 is formed, and the cavity 11 is formed by the inner wall surface of each of the slide inserts 12 arranged in the peripheral portion of the portion. Each slide insert 12 is slidably installed on the movable mold plate 15 by the angular pin 14 in the direction orthogonal to the mold opening direction.

The first protruding core 20 and the second protruding core 21 are integrally formed with the end portions of the first slant rod 25 and the second slant rod 26 on the lower outside by fastening members (not shown). It is fixed to. The first tilt rod 25 and the second tilt rod 26 penetrate through the movable side receiving plate 16 and the float plate 27 arranged between the movable side receiving plate 16 and the movable side mounting plate 18, respectively, to mount the movable side. On the protruding plate 2 placed near the plate 18
8 and the lower part 29 of the protruding plate. The first inclined rod 25 is held by a hole formed in the movable side receiving plate 16 so as to be movable back and forth in the mold opening direction at an angle of α ₂ with respect to the mold opening direction. That is, the first inclined rod 25
Is inserted so that it cannot move in the direction orthogonal to the mold opening direction with respect to the movable side receiving plate 16. Also, the first
The inclined rod 25 is loosely fitted to the float plate 27 so as to be movable in a direction orthogonal to the mold opening direction.

On the other hand, the second inclined rod 26 is held at an angle of β ₂ with respect to the mold opening direction by a hole formed in the float plate 27 so as to be movable back and forth only in the mold opening direction with respect to the float plate 27. There is. In addition, the second inclined rod 26
Is loosely fitted to the fixed-side mold plate 15 and the movable-side receiving plate 16 so as to be movable by a predetermined amount in the direction orthogonal to the mold opening direction. Where the angles α ₁ and α ₂ are α ₁ ≧ α
_Although there is a relation of ₂ , the angles β ₁ and β ₂ are not necessarily β ₁ ≧
It is not necessary to satisfy the relationship of β ₂ . Each first tilted rod 2
Pins 30 and 31 are attached to the ends of the second inclined rod 26 and the second inclined rod 26, respectively. Each of the pins 30 and 31 is held in a groove 32 and a groove 33 formed on the surface of the protruding plate 28 facing the lower protruding plate 29, and the lower protruding plate 29 causes the upper plate 28 and the protruding plate 29 to move. The relative movement in the mold opening direction is restricted. On the other hand, the grooves 32 and 33 are formed to have a diameter larger than that of the pins 30 and 31 in the direction orthogonal to the mold opening direction, and the pins 30 and 31, that is, the first inclined rod 25,
The end of the second inclined rod 26 is attached so as to be movable in a direction orthogonal to the mold opening direction.

The upper protruding plate 28, the lower protruding plate 29 and the float plate 27 are guided by guide pins 34 and are movably provided in the mold opening direction. Both ends of the guide pin 34 are fixed to the movable side receiving plate 16 and the movable side mounting plate 18, and are provided parallel to the mold opening direction.
A puller bolt 35 is slidably provided on the protruding plate upper portion 28 and the protruding plate lower portion 29 in parallel with the mold opening direction,
The end surface of the puller bolt 35 is fixed to the float plate 27. A puller bolt 35 is wound and a spring 36 is disposed between the upper protruding plate 28 and the float plate 27, and constantly biases the upper protruding plate 28, the lower protruding plate 29, and the float plate 27 so as to keep them away from each other. That is, when opening the mold,
Until the float plate 27 contacts the movable side receiving plate 27,
The distance between the float plate 27 and the lower and upper projections 28 and 29 is kept constant, and then the upper and lower projections 28 and 29 are fixed.
Both come close to the float plate 27.

Next, the operation of the processing die 1 of this embodiment will be described. First, in the state shown in FIG. 1, an injection molding machine (not shown)
After injecting a molten resin (not shown) into the cavity 11 to cool it, the mold is opened to separate the fixed mold part 2 and the movable mold part 3 at the parting surface. At this time, slide nest 12
Moves on the movable side mold plate 15 in the direction orthogonal to the mold opening direction by the angular pin 14 and releases from the molded product 37. After that, an ejecting rod (not shown) of the molding machine is inserted into the through hole 38 formed in the movable side mounting plate 18, and the lower extruding plate 29 is pushed to receive the lower extruding plate 29 and the upper extruding plate 29 together with the float plate 27. Move in the direction of plate 16. At this time, the first protruding core 20 moves in the mold opening direction (rightward in the drawing, the same applies hereinafter) together with the first inclined rod 25, while the first protruding core 12 moves in the central direction of the central core 19. .. As a result, the first protruding core 20 is separated from the molded product 37 (see FIG. 2). However, since the float plate 27 moves in the mold opening direction together with the second inclined rod 26, the second protrusion core 21 moves only in the mold opening direction together with the molded product 37, and does not move in the center direction of the central core 19. (See Figure 2).

Further, when the lower pushing plate 29 is pushed by the pushing rod of the molding machine, the float plate 27 comes into contact with the movable side receiving plate 16 and the subsequent movement in the mold opening direction is restricted. After that, if you push the bottom plate 29 of the protrusion further, the second
The second protruding core 21 moves in the mold opening direction together with the inclined rod 26 of FIG. As a result, the second protruding core 21 is formed into the molded product 37.
And the release of the undercut portion (helicoid screw) of the molded product 37 is completed.

At the time of mold clamping, the lower push-out plate 29 and the upper push-up plate 28 are first returned by a quick return pin (not shown) provided on the fixed-side mold plate 6, and the first push-out core 2
The 0 and second protruding cores 21 move in the direction opposite to the central direction of the central core 19 while moving backward. Further, when the lower protruding plate 29 and the upper protruding plate 28 are returned, the puller bolt 35 hits the lower protruding plate 29 and the float plate 27 is also returned, and the first protruding core 20 moves further backward and is opposite to the central direction of the central core 19. , While the second protruding core 21 moves only backward. This allows
Mold clamping is completed.

According to this embodiment, the first protruding core 2
Since 0 the angle alpha ₁ and the relationship between the angle alpha ₂ of the first inclined rod 25 is α ₁ ≧ α _2, when the first protruding core 20 and the first inclined rod 25 moves the angle alpha ₂ It slides on the slope of and does not slide on the slope of angle α ₁ . Also,
The second projecting core 21 and the second slanting rod 26 first move in the mold opening direction, and the slope of the second projecting core 21 and the central core 19 at the angle β ₁ are separated from each other. It is designed to slide on the surface of angle β ₂ . As described above, the positioning of the first protruding core 20 and the second protruding core 21 during molding (during mold clamping) is performed on the slopes of the angles α ₁ and β ₁ , and the first protruding core 20
And the first inclined rod 25 and the second protruding core 21.
Also, sliding when the second tilted rod 26 moves is performed on the slopes with angles α ₂ and β ₂ . Therefore, the angles α ₁ , β
The slope ₁ is not worn, and the positioning accuracy of the first protruding core 20 and the second protruding core 21 during molding (during mold clamping) can be maintained. Also, the first protruding core 2
Until 0 moves a certain amount toward the center of the central core 19,
Since the second protrusion core 21 does not move toward the center of the center core 19, the gap between the first protrusion core 20 and the second protrusion core 21 becomes large, and the molds are damaged without interference between them and biting. Hateful. Further, since the members that drive the first protruding core 20 and the second protruding core 21 are not arranged on the fixed-side mold plate 6 or the movable-side mold plate 15, the slide insert 12 and the angular pin 14 are arranged. There are no restrictions and the mold does not grow in size.

[0018]

[Embodiment 2] FIG. 6 is a cross-sectional view showing Embodiment 2 of the inner diameter undercut mold according to the present invention, showing the time of releasing the undercut portion of the molded product. Processing type 39 of this embodiment
Is provided with a pin 40 on the second inclined rod 26, and a cam 41 corresponding to the pin 40 is provided on the movable side receiving plate 16. The cam 41 is composed of a C portion and a D portion as shown in the drawing. The C portion is formed in the mold opening direction, that is, parallel to the axis of the central core 19, and the D portion is inclined at an angle β ₂ with the mold opening direction. It is configured. Other configurations are the same as those of the processing die 1 of the first embodiment except that the float plate 27, the puller bolt 35 and the spring 36 arranged in the processing die 1 of the first embodiment are not necessary.

Next, the operation of the processing mold 39 of this embodiment will be described. First, the ejecting rod lower (not shown) 29 and the protruding plate upper 28 by the ejecting rod (not shown) of the molding machine (not shown).
push. Then, the first protruding core 20 and the first inclined rod 25 move toward the center of the central core 19. As a result, the first protruding core 20 is separated from the molded product 37. At this time, since the pin 40 is engaged with the C portion of the cam 41, the action of the pin 40 and the cam 41 causes the second protruding core 21 and the second inclined rod 26 to first advance only. After that, when the pin 40 and the D portion of the cam 41 engage with each other by moving forward, the second protruding core 21 and the second inclined rod 26 move toward the center of the center core 19.
As a result, the second protruding core 21 is separated from the molded product 37. Then, the release of the undercut portion of the molded product 37 is completed. According to this embodiment, it is possible to obtain the same effect as that of the first embodiment.

[0020]

[Embodiment 3] FIGS. 7 and 8 show Embodiment 3 of the inner diameter undercut processing mold according to the present invention. FIG. 7 is a cross-sectional view of the processing mold, and FIG. It is a cross-sectional view of a processing type showing a state. In the processing mold 42 of this embodiment, a movable stripper plate 43 is arranged between the movable mold plate 15 and the movable receiving plate 16. The movable side stripper plate 43 has an opening 43a formed in the central portion thereof, and is disposed in contact with the movable side mold 15 to form a spacer 44.
It is sandwiched between the movable side receiving plate 16 and the movable side receiving plate 16.

A float plate 45 is provided between the spacers 44 so as to be movable in the mold opening direction and sandwiched between the movable side stripper plate 43 and the movable side receiving plate 16.
The central core 19 is inserted through the central portion. A spring 46 wound around the central core 19 is elastically mounted between the float plate 45 and the movable-side receiving plate 16 to constantly urge the float plate 45 toward the movable-side strip plate 43. A stopper 47 is attached to the central core 19 at a position of the opening 43a of the movable stripper plate 43, and the float plate 4
The movement of 5 is regulated within a certain range. The central core 19 is integrally fixed to the movable side receiving plate 16 by a fastening member (not shown).

The first inclined rod 25 and the second inclined rod 26 are provided so as to penetrate the float plate 45 and the movable side receiving plate 16, respectively, and their ends are free ends. The first inclined rod 25 has an angle α with respect to the mold opening direction.
It is held so as to be movable back and forth only in the mold opening direction by a hole formed in the movable side receiving plate 16 at an angle of ₂ . The first inclined rod 25 is loosely fitted to the float plate 43 so as to be movable in a direction orthogonal to the mold opening direction. On the other hand, the second inclined rod 26 has a β ₂
Is held by the hole formed in the float plate 43 so as to be movable back and forth only in the mold opening direction with respect to the float plate 43. In addition, the second inclined rod 26 is used for the fixed-side template 1
5 and the movable mold receiving plate 16 are loosely fitted so as to be movable by a predetermined amount in the direction orthogonal to the mold opening direction.
Further, the first inclined rod 25 and the second inclined rod 26 are integrally formed with collars 25a and 26a, respectively, and the collars 25a and 26a are sandwiched between the movable side template 15 and the movable side stripper plate 43, respectively. ..

A retainer 48 and a retainer 49 are planted on the respective side surfaces of the fixed side 6 and the movable side stripper plate 43. A tension link 50 having a groove (long hole) is provided between the retainers 48 and 49 by engaging the retainers 48 and 49 with the groove.
When the movable mold part 3 is separated from the retainer 48, 49
Respectively come into contact with both ends of the groove of the tension link 50, and the movable side stripper plate 43, the spacer 44, and the float plate 45 can be separated from each other. The other structure is the float plate 2 arranged in the processing mold 1 of the first embodiment.
7. The processing mold 1 has the same configuration as that of the first embodiment except that the puller bolt 35 and the spring 36 are not required.

Next, the operation of the processing die 42 of this embodiment will be described. First, in the state shown in FIG. 8, a molten resin is injected into the cavity 11 by an injection molding machine (not shown) and cooled, and then the mold is opened on the parting surface.
The retainers 48 and 49 are locked to both ends of the groove, pull the movable stripper plate 43 and the movable template 15, and the first tilt rod 25 and the second tilt rod 26 follow. Then, the first inclined rod 25 moves toward the center of the central core 19 while moving forward. As a result, the first protruding core 20 is separated from the molded product 37. Moreover, at this time, since the float plate 45 holding the second inclined rod 26 is pushed by the spring 46, the second projecting core 21 and the second inclined rod 27 together with the float plate 45 move in the right direction in the drawing. Central core only by moving forward to 19
Does not move toward the center of. Further, when the movable side stripper plate 43 and the movable side mold plate 15 are pulled by continuing the mold opening, the float plate 45 hits the stopper 47 and its forward movement is restricted. Then the second protruding core 2
The first and second inclined rods 26 move toward the center of the central core 19 while advancing to the right in the figure. As a result, the second protruding core 21 is separated from the molded product 37 (see FIG. 8).
reference). As a result, the release of the undercut portion of the molded product 37 is completed. At the time of mold clamping, when the movable side stripper plate 43 and the movable side mold plate 15 are first returned by the quick return pins (not shown) provided on the fixed side mold plate 6,
First protrusion core 20 and second protrusion core 21
Moves in a direction opposite to the central direction of the central core 19 while moving backward. Further, when the movable side stripper plate 43 and the movable side template 15 are returned, the float plate 45 is also returned by the movable side stripper plate 43, and the first protruding core 20 moves backward and remains opposite to the central direction of the central core 19. Moving in the direction, the second protruding core 21 moves only backward. This completes the mold clamping.

According to this embodiment, it is possible to obtain the same effect as that of the first embodiment. Also, the first protruding core 2
Since the ejection mechanism of the molding machine is not used for releasing the 0 and the second ejection cores 21, for example, the molded article 37 is ejected by the ejector pin after the first ejection core 20 and the second ejection core 21 are released. It is possible.

[0026]

According to the present invention, the positioning of the first protruding core and the second protruding core during molding (during mold clamping) is performed on the slopes of the angles α ₁ and β ₁ , and the first protruding core and Sliding of the first tilted rod with the second protruding core and the second tilted rod is performed with angles α ₂ and β ₂ respectively.
On the slope of. Further, by setting α ₁ ≧ α ₂ , the first protruding core and the first inclined rod slide at the angle α ₂ and do not slide on the surface at the angle α ₁ . Therefore, the angles α ₁ and β ₁ are not worn, and the angles α ₂ and β _{2 are}
Even if the sloped surface is worn, the positioning accuracy of the first protruding core and the second protruding core during molding (during mold clamping) is not affected. Further, after the first protrusion moves toward the center of the central core, the second protrusion core moves toward the center of the central core.
There is no risk of the protruding core of the die interfering with it and the durability of the mold is improved. Further, even if the outer periphery of the molded product is formed by the slide insert, the mold does not become large.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view showing a first embodiment of an inner diameter undercut processing mold according to the present invention.

FIG. 2 is a cross-sectional view showing the inner diameter undercut treatment mold of Example 1 during mold release.

FIG. 3 is a cross-sectional view showing the inner diameter undercut treatment mold of Example 1 at the time of mold release.

FIG. 4 is a plan view of the central core and the first and second protruding cores as seen from the direction of arrow A in FIG.

5 is a plan view of the central core and the first and second projecting cores as seen from the direction of arrow A in FIG.

FIG. 6 is a transverse cross-sectional view showing a second embodiment of an inner diameter undercut treatment mold according to the present invention, showing a mold release time.

FIG. 7 is a cross-sectional view showing a third embodiment of the inner diameter undercut processing type according to the present invention.

FIG. 8 is a cross-sectional view showing the inner diameter undercut treatment mold of Example 3 at the time of mold release.

FIG. 9 is a plan view showing a main part of a conventional molding die.

10 is a sectional view taken along line WW in FIG.

[Explanation of symbols]

 1, 39, 42 Inner-diameter undercut processing type 19 Central core 20 1st protrusion core 21 2nd protrusion core 25 1st inclination rod 26 2nd inclination rod

Claims (2)

[Claims] 1. A plurality of first projecting cores having a substantially trapezoidal cross section and second projecting cores having a substantially arcuate cross section are alternately arranged around the central core, and the first projecting core is provided. The protruding core of No. 1 is connected to a first tilting rod inclined at an angle α ₂ with respect to the mold opening direction, and
While holding the slant rod of the slidable rod in the direction of the angle α ₂ while connecting the second projecting core to the second slant rod which is slanted at the angle of β ₂ with respect to the mold opening direction. An inner diameter undercut mold characterized by holding two inclined rods slidably in the mold opening direction and the angle β ₂ direction. 2. The first protruding core is in contact with the inclined surface of the central core that is inclined at an angle α ₁ with respect to the mold opening direction,
The inner diameter undercut processing mold according to claim _{1, wherein the} angle α ₁ has a relationship of α ₁ ≧ α ₂ .