JP2010155381A - Undercutting treatment mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an undercutting treatment mechanism allowing easy mold removal even when a boss having a central hole inside a molding protrudes in a direction intersecting the direction of entire mold removal. <P>SOLUTION: An undercut molding core 30 contained in a holder 40 consists of a first core 31 moving in the direction of mold removal and a second core 32 arranged adjacent to the first core 31. The first and second cores 31 and 32 have adjacent and inclined side surfaces 33 and 34, respectively, and the side surfaces 33 and 34 are connected with each other in such a way that they can be pushed and pulled in the direction of mutual inclination in a relatively slidable state. In the holder 40, the first vertical groove 43 guiding the first core 31 in the direction of mold removal and the second lateral groove 44 guiding the second core 32, which is pushed or pulled so as to be interlocked with the movement of the first core 31 in the direction of mold removal, in such a direction as to be removable from an undercut part P1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an undercut processing mechanism that enables an undercut portion protruding in a direction intersecting with a die cutting direction of a molded product to be die-cut in a mold composed of a fixed die and a movable die.

  Conventionally, as this type of mold apparatus, for example, a loose core ejector apparatus described in Patent Document 1 is known. That is, it is locked to a mold core that forms the inner surface of the molded product, a movable loose core support rod that penetrates the core and is inclined with respect to the core surface, a movable mold plate, and a pedestal plate. And a slide base disposed in the slide path of the ejector plate so as to be slidable relative to the guide means rod, and the loose core support rod is interlocked with the movement of the slide base. .

  In such a loose core ejector device, one end of the guide means rod is locked to a holder that is tightly fitted in a recess formed in the lower surface of the movable side mold plate, and the loose core support rod is attached to the core. The insertion hole formed at substantially the same inclination angle as that of the guide means rod is slidably inserted, and this insertion hole is the only angle setting hole for setting the inclination angle of the loose core support rod.

JP 2002-326233 A

  However, in the conventional technology as described above, not only the loose core support rod but also the guide means rod are inclined, and the mechanism for moving each rod at the same inclination angle is an ejector plate and a movable side type. It is comprised so that it may disperse | distribute to a board. Therefore, a large installation space is required compared to the amount of movement of the piece with the undercut part shape necessary for die-cutting of the undercut part of the molded product, and the overall structure is complicated, requiring time and labor for assembly. There was a problem that it was difficult to reduce costs.

  In addition, it can only deal with the case where the undercut portion is in one direction outside or inside the molded product. For example, a boss having a center hole on the inside of the molded product is obliquely below the entire die cutting direction. In the case of projecting in the direction, it was impossible to die-cut such a molded product. Therefore, in addition to the shape of the undercut portion in the moldable molded product, there is a problem that the position and number are limited to a very narrow range.

  The present invention has been made paying attention to the problems of the prior art as described above, can be configured compactly, can meet the demand for space saving, and can be processed and incorporated into a mold. This makes it easy to cut costs, especially when a boss with a center hole on the inside of the molded product protrudes diagonally downward, intersecting the entire die cutting direction. An object of the present invention is to provide an undercut processing mechanism that can be used.

The gist of the present invention for achieving the object described above resides in the inventions of the following items.
[1] In a mold (11) composed of a fixed mold (12) and a movable mold (13), an undercut portion (P1) protruding in a direction intersecting with a mold cutting direction of the molded product (P) can be punched. An undercut processing mechanism,
An undercut molding core (30) for molding the undercut portion (P1), and the undercut molding core (30) can be moved inside the fixed mold (12) or the movable mold (13). Has a holder (40) to be stored
The undercut molding core (30) moves in the mold release direction from a molding position that fits within the holder (40) to a mold release position that is at least partially exposed outside the holder (40). And a second core (32) provided adjacent to the first core (31) and having a shape for forming the undercut portion (P1),
The first core (31) and the second core (32) have side surfaces (33, 34) that are adjacent to each other and are inclined in the direction in which the undercut portion (P1) protrudes. 34) are connected to each other so as to be able to push and pull while sliding relative to each other in an inclined direction,
In the holder (40), a first guide (43) for guiding the first core (31) in the die-cutting direction, and the first core (31) being pushed and pulled along with the movement in the die-cutting direction. An undercut processing mechanism, characterized in that a second guide (44) for guiding the interlocking second core (32) in a direction in which the second core (32) can be detached from the undercut portion (P1) is provided.

[2] The undercut portion (P1) is an undercut boss having a center hole (P2),
The second core (32) has a recess (35) for forming the undercut boss and a core (36) for forming the center hole (P2) in the recess (35). The undercut processing mechanism according to [1].

[3] It has an ejector pin (20) which is driven in the die-cutting direction and operates to protrude, and the first core (31) is fixed to the tip of the ejector pin (20).
[1] or [2], wherein the holder (40) is installed in the movable mold (13) in a state in which a tip portion of the ejector pin (20) is guided to be movable. Undercut processing mechanism.

[4] A first vertical groove (43) extending in a die-cutting direction in which the first core (31) moves is provided on one of the inner wall of the holder (40) and the outer wall of the first core (31). The first vertical strip (37) that extends in the die-cutting direction and is slidably fitted into the first vertical groove (43) is provided on either one of the first vertical strips in the holder (40). The groove (43) or the first vertical strip (37) is the first guide (43),
A second lateral groove extending in a direction in which the second core (32) can be detached from the undercut portion (P1) in which the second core (32) moves, on either the inner wall of the holder (40) or the outer wall of the second core (32) (44) is provided, and the other side is provided with a second horizontal strip (38) that extends in the detachable direction and is slidably fitted into the second lateral groove (44), and is provided in the holder (40). The undercut processing mechanism according to [1], [2] or [3], wherein the second horizontal groove (44) or the second horizontal strip (38) in the second guide (44) is used.

[5] The first core (31) is designed to have a length corresponding to a stroke that can be punched out of the entire molded product (P) including the undercut portion (P1). [1] The undercut processing mechanism according to [2], [3] or [4].

[6] The holder (40) itself is configured as a part of the movable mold (13) or the fixed mold (12) provided with the holder (40), [1], [2], The undercut processing mechanism according to [3], [4] or [5].

The present invention operates as follows.
According to the undercut processing mechanism described in [1], the undercut molding core (30) accommodated in the holder (40) includes the first core (31) moving in the die-cutting direction and the first A second core (32) arranged adjacent to the core (31), the first and second cores (31, 32) each having an inclined side surface (33, 34) adjacent to each other, The side surfaces (33, 34) are connected so as to be capable of being pushed and pulled while being relatively slid in directions inclined with respect to each other.

  Here, in the holder (40), a first guide (43) for guiding the first core (31) in the die-cutting direction, and a push-pull as the first core (31) moves in the die-cutting direction. A second guide (44) is provided for guiding the second core (32) that is interlocked with the second core (32) in a direction in which the second core (32) can be detached from the undercut portion (P1). Accordingly, when the molded product (P) is die-cut, the first core (31) is guided by the first guide (43) and is at least partially outside the holder (40) from the molding position within the holder (40). Move to the mold release direction to the mold release position where the is exposed.

  As the first core (31) moves in the die-cutting direction, the second core (32) is pushed and pulled together. At this time, the second core (32) is guided to the second guide (44). Then, the molded product (P) moves in a direction in which it can be detached from the undercut portion (P1). In this way, the undercut molded core (30) can be divided into two parts and displaced in a state of being separated from the undercut part (P1) while interlocking one with the other. As a result, for example, as described in [2] above, various molded products (P) having undercut bosses protruding in a direction intersecting the die cutting direction of the molded product (P) can be easily punched. It becomes possible to do.

  According to the undercut processing mechanism as described above, the overall structure can be simplified, and the manufacturing cost can be greatly reduced. Further, the member that supports the undercut molding core (30) is not dispersed in the ejector base plate or the movable mold (13), and the fixed mold (12) or the movable mold (13) is inserted through the holder (40). It can be concentrated on either one of them. As a result, a compact configuration can be achieved, a space-saving request can be met, and processing and incorporation into the mold (11) are facilitated.

  The undercut processing mechanism described in [3] operates in accordance with the ejecting operation of the ejector pin (20) driven in the die-cutting direction when the molded product (P) is die-cut. When molding is finished and the fixed mold (12) is separated from the movable mold (13), the outside of the molded product (P) appears. Next, the ejector pin (20) is pushed out so as to separate the molded product (P) from the movable die (13) for die cutting, and the tip of the ejector pin (20) moves in the holder (40). To do.

  Along with the ejecting operation of the ejector pin (20), the first core (31) fixed to the tip of the ejector pin (20) is moved by the first guide (43) provided in the holder (40). As it is, it is guided in the die-cutting direction. In conjunction with this, the second core (32) also moves reliably in the direction in which it can be detached from the undercut portion (P1), so that not only the main part of the molded product (P) but also the undercut portion (P1) It becomes a state which can be extracted, and the whole molded article (P) can be easily removed from the mold (11).

  Here, as described in [4] above, the first vertical length extending in the die-cutting direction in which the first core (31) moves on either the inner wall of the holder (40) or the outer wall of the first core (31). A groove (43) is provided, and a first vertical strip (37) that extends in the die-cutting direction and is slidably fitted in the first vertical groove (43) is provided on either one of the holders (40). The first longitudinal groove (43) or the first longitudinal strip (37) inside is defined as the first guide (43).

  On the other hand, a second lateral groove (44) extending in a direction in which the second core (32) can be detached from the inner wall of the holder (40) and the outer wall of the second core (32) from the undercut portion (P1) where the second core (32) moves. ) And a second horizontal strip (38) that extends in a detachable direction and fits slidably into the second lateral groove (44) is provided in either one of the holders (40). The second horizontal groove (44) or the second horizontal strip (38) is defined as a second guide (44).

  Thereby, the movement of each of the first and second cores (31, 32) is caused by the grooves (43, 44) and the strips (37) provided in the first and second cores (31, 32) themselves and the holder (40). , 38) is reliably and smoothly guided, and the load at the time of die-cutting is distributed without being concentrated in one place, so that durability is improved. In addition, since high accuracy at the time of design is eased, further cost reduction is possible.

  According to the undercut processing mechanism described in [5], the first core (31) is made to have a length corresponding to the stroke that can be punched out of the entire molded product (P) including the undercut portion (P1). design. Thereby, it can respond | correspond suitably from the big stroke in the die cutting of a molded article (P) to a small stroke.

  According to the undercut processing mechanism described in [6] above, the holder (40) itself is configured as a movable mold (13) or a fixed mold (12) provided with the holder (40). In other words, a hollow portion serving as a substitute for the internal space of the holder (40) is directly formed in the mold (11), and the first and second cores (31, 32) may be movably accommodated in the hollow portion. . As a result, the holder (40) part is not required, the number of parts is reduced, the configuration of the entire apparatus can be further simplified, and the cost can be further reduced.

  According to the undercut processing mechanism according to the present invention, even when there is a boss-shaped undercut portion having a center hole among molded products having an undercut portion protruding in a direction intersecting with the die cutting direction of the molded product. Can be easily punched out.

  In addition, it can be configured compactly, can meet the demands for space saving, can be easily processed and assembled into the mold, is simple in configuration, does not require time and effort for assembly, and costs Down can be realized.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment that represents the present invention will be described based on the drawings.
FIG. 1 and FIG. 2 are cross-sectional views for explaining the operation of the mold 11 and the undercut processing mechanism constituting the molding die apparatus 10 according to the present embodiment. FIG. 1 shows a state when the molded product P is molded, and FIG. 2 shows a state when the molded product P is released. The molding die apparatus 10 is an apparatus that molds a molded product P having an undercut portion P <b> 1 with a mold 11.

  As shown in FIG. 1, the molded product P according to the present embodiment is a plate-like member as a whole and has an undercut portion P1 on the inner surface side thereof. The undercut portion P1 is a tubular undercut boss having a center hole P2. The undercut portion P1 protrudes obliquely downward with respect to the horizontal inner surface of the molded product P, that is, in a direction intersecting the die cutting direction perpendicular to the horizontal plane. The material of the molded product P is not limited to a synthetic resin such as plastic, and a metal such as iron or copper is also applicable.

  As shown in FIGS. 1 and 2, the mold 11 of the molding die apparatus 10 molds the fixed mold 12 that molds the outer surface side of the molded product P and the inner surface side including the undercut portion P1 of the molded product P. And a movable mold 13. A movable mounting plate 14 is arranged below the movable mold 13, and an ejector base plate 15 made of a double-layered plate material can move between the movable mold 13 and the movable mounting plate 14 in the vertical direction. It is arranged.

  The undercut processing mechanism that forms the basis of the present invention enables the undercut portion P1 to be die-cut when the molded product P is die-cut. The ejector pin 20 that is driven in the die-pulling direction to perform an ejection operation, and the ejector A holder 40 in which the tip 23 of the pin 20 is slidably guided, and an undercut molding core 30 connected to the tip 23 of the ejector pin 20 and movably disposed in the holder 40, etc. Become.

  As shown in FIGS. 1 and 2, the ejector pin 20 is formed of a round bar member, and is erected in a vertical state on the ejector base plate 15. A base end portion 22 of the ejector pin 20 is fixed to the ejector base plate 15 via a knock pin 21. As the ejector base plate 15 moves upward, the ejector pin 20 is driven in the die-cutting direction to project. The tip 23 of the ejector pin 20 is slidably inserted into the holder 40. The movable die 13 is provided with a vertical hole 13a through which the ejector pin 20 passes, and such a part may be combined as a separate block 13b.

  The holder 40 is integrally provided in the movable mold 13 while being accommodated in the movable mold 13. As shown in FIGS. 3 to 6, the holder 40 is formed by combining two components, and is formed in a box shape including an internal space 41 having an open upper end surface. A vertical hole 42 through which the ejector pin 20 is inserted is formed on one end side of the lower end surface of the holder 40, and the ejector pin 20 is separated from the molding position (see FIG. 1) on one end side of the inner space 41 of the holder 40. It is slidably inserted into the mold position (see FIG. 2). Moreover, the undercut molding core 30 is accommodated in the holder 40 in a movable state.

  The undercut molding core 30 is adjacent to the first core 31 and the first core 31 that moves in the mold release direction from the molding position that fits in the holder 40 to the mold release position that is partially exposed outside the holder 40. And a second core 32 having a shape for forming the undercut portion P1. As shown in FIGS. 4 and 5, the first and second cores 31, 32 are formed from the illustrated piece-shaped members, and are side surfaces 33, which are inclined adjacent to each other in the direction in which the undercut portion P <b> 1 protrudes. 34. Here, the side surfaces 33 and 34 are connected so as to be capable of being pushed and pulled while relatively sliding in directions inclined with respect to each other.

  Specifically, a dovetail groove 33a extending in the inclined direction is provided on the side surface 33 inclined obliquely downward on the left end side of the first core 31. On the other hand, a side surface 34 inclined obliquely upward on the right end side of the second core 32 is provided with a protrusion 34a extending in the inclination direction and slidably fitted in the dovetail groove 33a. With the side surface 33 of the first core 31 riding on the side surface 34 of the second core 32, the protrusion 34 a on one side surface 34 is slidably fitted in the dovetail groove 33 a on the other side surface 33.

  The tip 23 of the ejector pin 20 is fixed to the lower end side of the first core 31 by screwing. The upper end side of the second core 32 is provided with a recess 35 for forming the boss shape of the undercut portion P1 and a core 36 for forming the center hole P2 in the recess 35. Yes. As shown in FIG. 5, the core 36 is a member that is originally configured as a separate body from the second core 32 and is later incorporated into the recess 35.

  As shown in FIG. 5, a first guide that guides the first core 31 in the die-cutting direction when the molded product P is die-cut is provided on the inner wall of the inner space 41 of the holder 40. The first guide has a concave groove cross-sectional shape that guides the first core 31 from the molding position (see FIG. 4) to the mold release position (see FIG. 7) in the die-cutting direction which is the vertical direction in FIG. One vertical groove 43 is provided. The first vertical grooves 43 are provided so that a pair of the first vertical grooves 43 are opposed to both front and rear wall surfaces of the holder 40.

  On the other hand, on the front and rear of the right end side of the first core 31, first vertical strips 37 are provided so as to be slidably fitted in first vertical grooves 43 in the holder 40. Here, the first vertical stripe 37 may be provided on either the outer wall of the first core 31 or the inner wall of the holder 40, and the first vertical groove 43 is provided on either one of them. In short, any configuration may be adopted as long as the first core 31 is guided so as to be movable in the die-cutting direction as it is during the die-cutting operation.

  Further, the second core 32 that is pushed and pulled in conjunction with the movement of the first core 31 in the die-cutting direction on the inner wall of the inner space 41 of the holder 40 in a direction in which the second core 32 can be detached from the undercut portion P1. A second guide for guiding is provided. The second guide is a recess that guides the second core 32 from the molding position (see FIG. 4) to the release position (see FIG. 7) in the holder 40 along the horizontal direction in FIG. It is provided as a second transverse groove 44 having a rectangular cross section. In addition, like the second horizontal groove 44 and the first vertical groove 43, a pair is provided to face both front and rear wall surfaces of the holder 40.

  On the other hand, at the intermediate portion of the front and rear end surfaces of the second core 32, second horizontal strips 38 are provided so as to be slidably fitted into the second horizontal grooves 44 in the holder 40, respectively. Here, the second horizontal stripe 38 may be provided on either the outer wall of the first core 31 or the inner wall of the holder 40, and the second horizontal groove 44 is provided on either one of them. In short, any configuration may be used as long as the second core 32 is guided so as to be able to move away from the undercut portion P1 in conjunction with the movement of the first core 31 during the die cutting operation.

Next, the operation of this embodiment will be described.
As shown in FIG. 1, a molded product P is molded by a molding die apparatus 10. At this time, in the holder 40 in the movable mold 13, the first core 31 and the second core 32 constituting the undercut molding core 30 are overlapped in a state where the upper end surfaces are horizontally connected, as shown in FIG. 4. Overall, it has a cubic shape. The undercut part P1 of the molded product P is molded by the second core 32 of the undercut molded core 30 having such a shape.

  As shown in FIG. 2, when the molding is finished and the fixed mold 12 is separated from the movable mold 13, the ejector base plate 15 is driven upward. Then, the ejector pin 20 erected on the ejector base plate 15 projects straightly in the mold release direction (upward) while passing through the vertical hole 13a in the movable mold 13.

  In the holder 40, the first core 31 fixed to the tip portion 23 of the ejector pin 20 moves together with the ejector pin 20 in the mold release direction (upward). Here, the first core 31 is guided in the mold release direction (upward) while the first vertical line 37 slides in the first vertical groove 43 which is the first guide in the holder 40.

  On the other hand, the second core 32 connected to the first core 31 is pushed and pulled as the first core 31 moves in the mold release direction (upward). Here, the moving direction of the second core 32 is restricted by the second guide 44 in the holder 40. That is, the second core 32 is in a direction in which the second horizontal stripe 38 can be detached from the undercut portion P1 while sliding in the second horizontal groove 44 as the second guide in the holder 40 in FIG. It will move to the right along the horizontal direction.

  In this way, the undercut molded core 30 can be divided into two, and the first and second cores 31 and 32 can be displaced in a state of separating from the undercut portion P1 while interlocking in different directions. Accordingly, even a molded product P having a boss-like undercut portion P1 having a center hole P2 projecting in a direction intersecting with the die cutting direction of the molded product P can be easily molded or die-cut. .

  Further, according to the fitting relationship between the grooves 43 and 44 forming the first and second guides in the holder 40 and the strips 37 and 38 in the first and second cores 31 and 32, the first and second cores 31 and 32 can be reliably and smoothly guided from the respective molding positions to the release positions. In addition, since the load at the time of punching out the molded product P is also distributed without being concentrated in one place, the durability is improved. In addition, since high accuracy at the time of design is eased, further cost reduction is possible.

  Furthermore, the first and second cores 31 and 32 can be concentrated on the movable mold 13 via the holder 40 without being dispersed on the ejector base plate 15 and the movable mold 13. As a result, the entire molding die apparatus 10 can be configured in a compact manner, and a space-saving request can be met, and processing and incorporation into the die 11 are facilitated. In particular, the undercut processing mechanism can be configured as a unit in the form of being previously incorporated in the holder 40.

  In FIG. 2, when the molded product P is removed, as the ejector pin 20 returns to the molding position, the first and second cores 31 and 32 return to the initial position. Further, the fixed mold 12 also returns to the molding position, and the next molded product P is molded. By the way, the 1st core 31 is designed by the length according to the stroke which can carry out die cutting of the whole molded article P including the undercut part P1. Thereby, it can respond | correspond suitably from the big stroke in the die cutting of the molded article P to a small stroke.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to the above-described embodiments, and the present invention can be changed or added without departing from the scope of the present invention. Included in the invention. For example, the shapes of the molded product P and the first and second cores 31 and 32 are not limited to those specifically illustrated.

  In the embodiment, the holder 40 is integrally provided in the movable mold 13. However, the holder 40 may be integrated in the fixed mold 12 instead of the movable mold 13. Furthermore, the holder 40 itself may be configured as a part surrounding the hollow portion of the movable mold 13 (or the fixed mold 12).

  That is, it is only necessary to form a hollow portion directly in place of the inner space of the holder 40 in the mold 11 and accommodate the undercut molding core 30 and the like in the hollow portion. Thereby, the number of parts regarding the holder 40 can be reduced, the configuration of the entire molding die apparatus 10 can be further simplified, and the cost can be reduced.

It is sectional drawing explaining the operation | movement at the time of shaping | molding of the shaping die apparatus which concerns on embodiment of this invention, and an undercut process mechanism. It is sectional drawing explaining the operation | movement at the time of die-cutting of the shaping die apparatus which concerns on embodiment of this invention, and an undercut process mechanism. It is a perspective view showing the appearance of the whole undercut processing mechanism concerning an embodiment of the invention. It is a perspective view which removes a part of holder of the undercut processing mechanism which concerns on embodiment of this invention, and shows an inside. It is a perspective view which decomposes | disassembles and shows the undercut process mechanism which concerns on embodiment of this invention. It is a perspective view which shows the external appearance of the whole at the time of die cutting of the undercut processing mechanism which concerns on embodiment of this invention. It is a perspective view which removes a part of the holder at the time of die cutting of the undercut processing mechanism which concerns on embodiment of this invention, and shows an inside.

Explanation of symbols

P ... Molded product P1 ... Undercut portion P2 ... Center hole 10 ... Molding die device 11 ... Mold 12 ... Fixed die 13 ... Moving die 13a ... Vertical hole 13b ... Block 14 ... Moving mounting plate 15 ... Ejector base plate 20 ... Ejector pin 21 ... Knock pin 22 ... Base end 23 ... Tip 30 ... Undercut molded core 31 ... First core 32 ... Second core 33, 34 ... Side 33a ... Dovetail groove 34a ... Projection 35 ... Recess 36 ... Middle Child 37 ... 1st vertical strip 38 ... 2nd horizontal strip 40 ... Holder 41 ... Internal space 42 ... Vertical hole 43 ... 1st vertical groove (1st guide)
44 ... Second lateral groove (second guide)

Claims (6)

In a mold composed of a fixed mold and a movable mold, an undercut processing mechanism that enables a mold to be removed from an undercut portion that protrudes in a direction that intersects with the mold-cutting direction of a molded product,
An undercut molding core for molding the undercut portion, and a holder that is provided in the fixed mold or the movable mold and accommodates the undercut molding core in a movable state,
The undercut molding core is disposed adjacent to the first core, which moves in a mold release direction from a molding position that fits in the holder to a mold release position that is at least partially exposed outside the holder. A second core having a shape for forming the undercut portion.
The first core and the second core are adjacent to each other and have side surfaces inclined in the direction in which the undercut portion protrudes, and the side surfaces are pushed and pulled in a state of sliding relative to each other in the inclined direction. Concatenated,
A first guide for guiding the first core in the die-cutting direction in the holder, and the second core pushed and pulled in conjunction with the movement of the first core in the die-cutting direction from the undercut portion. An undercut processing mechanism, characterized in that a second guide is provided for guiding in a detachable direction. The undercut portion is an undercut boss having a center hole,
2. The undercut processing mechanism according to claim 1, wherein the second core includes a recess for forming the undercut boss and a core for forming the center hole in the recess. Having an ejector pin that is driven in the die-cutting direction and protrudes, and the first core is fixed to the tip of the ejector pin;
The undercut processing mechanism according to claim 1, wherein the holder is provided in the movable mold in a state in which a tip portion of the ejector pin is guided so as to be movable. Either one of the inner wall of the holder and the outer wall of the first core is provided with a first vertical groove extending in the die-cutting direction in which the first core moves. A first longitudinal groove that is slidably fitted into one longitudinal groove, and the first longitudinal groove or the first longitudinal line in the holder is the first guide;
Either one of the inner wall of the holder and the outer wall of the second core is provided with a second lateral groove extending in a direction capable of being detached from the undercut portion where the second core moves, and the other side is also removable. The second horizontal groove extending in the direction and slidably fitted in the second horizontal groove is provided, and the second horizontal groove or the second horizontal stripe in the holder is used as the second guide. The undercut processing mechanism according to 1, 2 or 3. 5. The undercut processing mechanism according to claim 1, wherein the first core is designed to have a length corresponding to a stroke in which the entire molded product including the undercut portion can be punched. . The undercut processing mechanism according to claim 1, 2, 3, 4, or 5, wherein the holder itself is configured as a part of the movable type or the fixed type provided with the holder.

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