JP2006272753A - Mold and molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold obtaining a molded product with a shape that is difficult to mold by a mold using the conventional rotary core or slide core. <P>SOLUTION: On one end of a rotary core 8 a projection 35 is formed and in its center a cam groove 37 consisting of a first groove 37a and a second groove 37b is formed. The projection 35 is the one for molding a L-shaped projection 15 (undercut part) of a molded product 14. The other end of the rotary core 8 is freely rotatably held by ejection plates 26, 27. The cam groove 37 is engaged with a fixed pin fixed on a striking plate 22. When the ejection plates 26, 27 are pushed by an ejection rod (not shown in Fig.), the rotary core 8 moves by sliding as shown in Fig. 5(B) and rotates as shown in Fig. 5(C). The projection 35 of the rotary core 8 is separated from the L-shaped projection 15 of the molded product 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold and a molding method for molding a resin molded product having an undercut portion.

  Conventionally, a mold for molding a resin molded product, for example, an injection mold is known. When the molded product has an undercut portion, the molded product cannot be taken out unless the undercut portion is released after molding. Therefore, it is necessary to devise the mold structure in order to release the undercut portion. As one of them, it is known that a core having a part for molding an undercut part of a molded product is incorporated in a mold, and the part is released from the undercut part by displacing the core after molding. . Examples of the core incorporated in the mold include a rotating core and a slide core.

  Patent Documents 1 and 2 describe a mold using a rotating core. The mold described in Patent Document 1 has a rotating core with a protruding gear, a cam ring with a gear that meshes with the gear of the rotating core and a cam ring in which a cam groove is formed, and a slidable with the cam groove of the cam ring. A cam ring guide member having a protrusion is formed, a cam ring guide member driving means for controlling the movement of the cam ring, and the like. After opening the mold, the cam ring guiding member is moved by the cam ring guiding member driving means, and the rotating core is rotated through each part.

  The mold described in Patent Document 2 includes a rotating core having a screw portion, an eject core, a separation operation mechanism for separating the rotation core from the eject core, and a rotation for rotating the rotation core in conjunction with driving of the separation operation mechanism. An operating mechanism is provided. After the mold is opened, the pulling operation mechanism is driven to rotate the rotating core through each part.

  In the metal molds described in Patent Documents 1 and 2, the rotating core only performs a rotating operation, and its use is limited when the undercut portion of the molded product has a screw shape or a spiral shape.

Patent Document 3 describes a mold using a slide core. The mold includes a slide core that slides in the protruding direction of the molded product and slides in a direction perpendicular to the protruding direction. After the mold is opened, the slide core is moved along with the protruding operation of the molded product to release the undercut portion of the molded product. In addition, the shape of the undercut part of a molded product is a convex shape.
JP 9-201827 A JP 2004-50523 A JP-A-9-155930

  In the mold described in Patent Document 3, when the convex undercut portion of the molded product becomes large, the slide amount of the slide core increases accordingly, and a large movement space of the slide core must be ensured. For this reason, when a part of the molded product is located in the moving direction of the slide core, the slide core and the molded product interfere with each other, so that molding is impossible.

  An object of the present invention is to provide a mold and a molding method capable of molding a molded product having a shape that has been difficult to mold with a mold using a conventional rotating core or slide core. The mold of the present invention has a simple structure and has a small space for movement, so that a large number of molded products can be obtained. In addition, as the shape of the molded product, which was difficult to mold with a conventional mold using a rotating core or slide core, the other part of the molded product is formed around the undercut part of the molded product. In addition, a shape in which the depth of the undercut portion is deep may be mentioned.

  The present invention relates to a mold for molding a molded product having an undercut portion, and is attached to a pair of mold plates each having a fixed side and a movable side that are separated from each other when the mold is opened, and the movable side mold plate. A rotary core having a portion for forming a cut portion, and after the mold is opened, the rotary core is slid in the direction in which the molded product is projected and then rotated to release the portion from the undercut portion of the molded product. And a rotary core displacement means.

  The rotating core is formed in a columnar shape, and the rotating core displacing means slides with respect to the movable side mold plate when the molded product protrudes, and a protruding plate that rotatably supports the rotating core; A cam groove formed on a peripheral surface of the rotary core and including a first groove parallel to the central axis of the rotary core and a second groove having an angle with respect to the central axis, and engages with the cam groove. And it is preferable to comprise from the fixed pin fixed with respect to the said movable side template.

  The rotating core displacing means includes a protruding plate that slides relative to the movable side mold plate when the molded product is protruded, and one end portion fixed to the rotating core and the other end portion being freely rotatable on the protruding plate. An extrusion pin that is supported and pushes out the rotary core, a fixed core that is inserted through the extrusion pin and engages with the rotary core and is fixed to the movable side template, and a rotary core formed on the rotary core A side cam portion and a fixed core side cam portion which is formed on the fixed core and is combined with the rotary core side cam portion and guides the rotary core side cam portion when the rotary core is pushed out. .

  The portion is tapered such that the cross-sectional width when cut along the central axis of the rotating core decreases toward the direction away from the fixed-side template, and the rotating core is formed of the molded product. It is preferable to position the movable side mold plate by using the taper when returning toward the movable side mold plate after taking out.

  The present invention relates to a molding method for molding a molded product having an undercut portion using a mold, a pair of mold plates composed of a fixed side and a movable side, a core mounted on the movable side mold plate, and the core And forming a molded product by pouring a molten material into a space formed by a rotating core having a part that forms a part of the undercut portion of the molded product and a cavity formed in the fixed-side template. After the mold is opened, the rotary core is slid in the direction in which the molded product is projected and then rotated to release the part from the undercut portion of the molded product.

  According to the mold of the present invention, a pair of mold plates consisting of a fixed side and a movable side that are separated from each other when the mold is opened, and a rotating core having a portion that is mounted on the movable side mold plate and molds an undercut portion of a molded product, Since the rotary core is slid in the direction in which the molded product protrudes after the mold is opened and rotated, and the rotary core displacement means for releasing the part from the undercut portion of the molded product is provided. A molded product having a shape difficult to mold with a mold using a slide core can be molded. As the shape of the molded product that was difficult to mold with a mold using a conventional rotating core or slide core, the shape of the other part of the molded product formed around the undercut part of the molded product, A shape where the depth of the undercut part is deep is mentioned.

  The rotary core is formed in a columnar shape, and the rotary core displacement means is a projecting plate that slides relative to the movable mold plate when the molded product is ejected and rotatably supports the rotary core, and a peripheral surface of the rotary core And a cam groove formed of a first groove parallel to the central axis of the rotary core and a second groove having an angle with respect to the central axis, and a cam groove engaging with the cam groove and fixed to the movable side mold plate. Therefore, the number of components can be reduced and a simple structure can be obtained. Also, the rotating core does not take up a large space in the mold. Furthermore, it is possible to obtain a large number of molded products by incorporating a plurality of rotating cores in the mold.

  The rotating core displacing means includes a protruding plate that slides relative to the movable mold plate when the molded product is protruded, and one end portion fixed to the rotating core and the other end portion rotatably supported by the protruding plate. An extrusion pin to be extruded, a fixed core that is inserted through the extrusion pin and engages with the rotary core and is fixed to the movable mold plate, a rotary core side cam portion formed on the rotary core, and a rotation formed on the fixed core Since it is composed of a fixed core side cam portion that is combined with the core side cam portion and guides the rotary core side cam portion when the rotary core is pushed out, the number of components can be reduced and a simple structure can be achieved. Also, the rotating core does not take up a large space in the mold. Furthermore, it is possible to obtain a large number of molded products by incorporating a plurality of rotating cores in the mold.

  The part for forming the undercut portion of the molded product (a part of the rotating core) has a taper such that the cross-sectional width when cutting along the central axis of the rotating core decreases toward the direction away from the fixed side template. The rotary core is positioned with respect to the movable side mold plate by using a taper when returning to the movable side mold plate after taking out the molded product. Accurate positioning. Thereby, the manufacturing precision of a molded article is improved.

  According to the molding method of the present invention, a pair of mold plates composed of a fixed side and a movable side, a core mounted on the movable side mold plate, and a portion forming a part of the core and forming an undercut portion of the molded product The molten material is poured into the space formed by the rotary core having the mold and the cavity formed in the fixed side mold plate to form a molded product, and after the mold is opened, the rotary core is slid in the direction in which the molded product is projected. Since the part is released from the undercut portion of the molded product, it is possible to mold a molded product having a shape that was difficult to mold with a mold using a conventional rotating core or slide core. .

[First Embodiment]
As shown in FIG. 1, an injection mold (hereinafter referred to as a mold) 2 includes a fixed side unit 3 and a movable side unit 4. A cavity 5 is formed between the fixed side unit 3 and the movable side unit 4. The movable unit 4 can move with respect to the fixed unit 3.

  The fixed side unit 3 has a fixed side template 6. The stationary side template 6 surrounds the cavity 5 together with the core 7 and the rotating core 8 described later. A nozzle 9 and a sprue 10 are formed on the fixed-side template 6, and molten resin is poured into the cavity 5 through the nozzle 9 and the sprue 10. A cavity for forming a cavity (space part) 5 is formed in the fixed-side template 6.

  A molded product formed by pouring molten resin into the cavity 5 is shown in FIG. The molded product 14 is, for example, a rectangular plate, and is formed with an L-shaped protrusion 15 and a protrusion 16 having a U-shaped cross section. The L-shaped protrusion 15 is an undercut portion. The U-shaped protrusion 16 is arranged so as to surround the L-shaped protrusion 15.

  As shown in FIG. 1, the movable side unit 4 includes a core 7, a rotating core 8, a movable side template 20, a protruding mechanism 21, a receiving plate 22, a spacer 23, a movable side mounting plate 24, and the like.

  The movable side template 20 holds the core 7. A receiving plate 22 is fixed to the back surface of the movable side template 20 (the surface opposite to the surface in contact with the fixed side template 6). The receiving plate 22 is fixed to the movable side mounting plate 24 via a spacer 23.

  The ejecting mechanism 21 has an ejecting pin 25 and two projecting plates 26 and 27. The protruding pin 25 is inserted into a through hole formed in the core 7, the movable side mold plate 20, and the receiving plate 22, and one end portion 25 a is in contact with the cavity 5. The other end 25b of the protrusion pin 25 is fixed to two protrusion plates 26 and 27 fixed to each other. The ejection pin 25 is used when a molded product is ejected when the mold is opened.

  The protruding plates 26 and 27 are slidably disposed in a hollow portion 28 formed in the central portion of the spacer 23. The protruding plates 26 and 27 are urged toward the movable side mounting plate 24 by a spring (not shown), and are pressed against the movable side mounting plate 24 in normal times. When a pressing force is received from a projecting rod (not shown) inserted from an opening 29 formed in the movable side mounting plate 24, the projecting plates 26 and 27 slide in a direction approaching the cavity 5.

  As shown in FIG. 3, the rotary core 8 is formed in a substantially cylindrical shape. A protrusion 35 is formed at one end of the rotary core 8 so as to protrude in the radial direction, and this protrusion 35 is a portion for forming the L-shaped protrusion 15 of the molded product 14, that is, the undercut portion. The other end portion of the rotary core 8 is an enlarged diameter portion 36 whose diameter is increased. A cam groove 37 is formed on the peripheral surface of the central portion of the rotary core 8. The cam groove 37 has the same groove depth in any region, and includes a first groove portion 37 a parallel to the central axis 40 of the rotary core 8, and a second groove portion 37 b having an angle with respect to the central axis 40. have.

  As shown in FIG. 1, the rotary core 8 is inserted into a through hole formed in the core 7, the movable side mold plate 20, and the receiving plate 22, and a position slightly separated from the protrusion 35 is held in the bearing portion 38. The enlarged diameter portion 36 is rotatably held by the protruding plates 26 and 27. Thereby, the rotary core 8 can move in the protruding direction (extrusion direction) and the return direction together with the protruding plates 26 and 27 and can rotate. The cam groove 37 of the rotary core 8 engages with a cylindrical fixing pin 39 fixed to the receiving plate 22. Since the receiving plate 22 is fixed to the movable side mold plate 20, the fixed pin 39 is fixed to the movable side mold plate 20. Before the rotary core 8 is pushed out, the fixing pin 39 is located at the end of the first groove portion 37a of the cam groove 37 on the fixed-side template side.

  4 is a cross-sectional view of the periphery of the protrusion 35 when cut along the line IV-IV in FIG. 1. As can be seen from this figure, the protrusion 35 of the rotary core 8 is in a direction away from the fixed-side template 6. It is tapered so that the cross-sectional width becomes smaller as it goes. Further, the receiving portion 7 a of the core 7 that receives the protrusion 35 is tapered in accordance with the taper of the protrusion 35 of the rotating core 8. This is because the rotary core 8 is accurately positioned in the core 7 by using the taper of the protrusion 35 of the rotary core 8 and the taper of the receiving portion 7a of the core 7 when the rotary core 8 returns after the molded product 14 is taken out. This is to make it happen. In addition, the lower part of the receiving part 7a of the core 7 is also tapered (a drop gradient) so that the molded product 14 can be easily removed.

  Hereinafter, the operation of the above configuration will be described. After the mold clamping, injection, pressure holding, and cooling operations are performed using the mold 2, the movable side unit 4 moves away from the fixed side unit 3, and the mold is opened.

  When the mold opening is performed, the fixed-side mold plate 6 (see FIG. 1) is released from the molded product 14 as shown in FIG. The fixing pin 39 is located at the end of the first groove portion 37 a of the cam groove 37.

  As shown in FIG. 5 (B), when a protruding rod (not shown) starts pressing the protruding plates 26 and 27, the protruding operation of the molded product 14 is started by the protruding pin 25. At the same time, the fixing pin 39 relatively moves along the first groove portion 37a, and the rotary core 8 slides in the protruding direction without rotating. Thereby, the molded product 14 is released from the core 7. The rotary core 8 moves to a position where the rotation operation is not interfered, that is, a position where the movement of the protrusion 35 is allowed.

  As shown in FIG. 5C, when a protrusion rod (not shown) continues to press the protrusion plates 26 and 27, the molded product 14 is further protruded by the protrusion pin 25. At the same time, the fixing pin 39 moves from the first groove portion 37a to the second groove portion 37b and relatively moves along the second groove portion 37b, and the rotary core 8 moves in the protruding direction while rotating. Thereby, the protrusion 35 (see FIG. 5B) of the rotary core 8 is released from the L-shaped protrusion 15 of the molded product 14, that is, the undercut portion.

  Since each part is released from the molded product 14, the molded product 14 can be taken out. When the projecting rod (not shown) is retracted after the molded product 14 is taken out, the projecting plates 26 and 27 start to move back to the original position, that is, the position shown in FIG. 5 (A) by the biasing force of the spring (not shown). To do. Along with this, the ejection pin 25 also moves in the return direction. In addition, the fixing pin 39 relatively moves along the second groove portion 37b and the first groove portion 37a, and after the rotary core 8 moves in the return direction while rotating in the reverse direction, it does not rotate in the return direction. Move the slide. Here, when the protrusion 35 of the rotating core 8 returns to the receiving portion 7a (see FIG. 4) of the core 7, the protrusion 35 and the receiving portion 7a are tapered. Positioned.

  Thereafter, the movable side unit 4 moves in a direction approaching the fixed side unit 3 to perform mold clamping, and the above operations are repeated again.

  Thus, according to the mold of the present invention, it is possible to mold a molded product having a shape that is difficult to mold with a conventional mold using a rotary core or a slide core. For example, it is possible to mold a molded product having a shape in which another part of the molded product is formed around the undercut portion of the molded product or a shape having a deep depth of the undercut portion. The mold of the present invention has a simple structure. Since the rotary core does not take up space in the mold, a large number of molded products can be obtained by incorporating a plurality of rotary cores in the mold.

  In addition, the cam groove formed in the rotating core is not limited to the above-described shape as long as it has a shape in which the rotating core is slid to a rotatable position and then rotated.

[Second Embodiment]
A mold having a configuration different from the mold described in the first embodiment is shown in the second embodiment. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 6, in the metal mold | die 100 of 2nd Embodiment, the rotating core 101 is used instead of the rotating core 8 of 1st Embodiment. One end portion 105 a of the push pin 105 is fixed to the rotary core 101, and the enlarged diameter portion 105 b formed on the other end side of the push pin 105 is rotatably held by the push plates 102 and 103. As a result, the rotating core 101 can move in the protruding direction together with the pushing pin 105, and can rotate. The rotating core 101 is engaged with a fixed core 104, and the fixed core 104 is fixed to the movable side mold plate 20 and the receiving plate 22.

  As shown in FIG. 7, the rotating core 101 is formed in a cylindrical shape. A protrusion 108 similar to the protrusion 35 of the first embodiment is formed at one end of the rotary core 101. Two cam protrusions 109 are provided on the other end side of the rotary core 101 so as to protrude in the axial direction. The cam protrusions 109 are arranged to face each other with the central axis 110 of the rotary core 101 interposed therebetween. A guide surface 109a, a guide surface 109b, and a guide surface 109c are formed on the cam protrusion 109 in order from the end. The guide surface 109 a and the guide surface 109 c are parallel to the central axis 110, and the guide surface 109 b has an angle with respect to the central axis 110. A guide surface 109d is formed on the cam projection 109 on the side opposite to the side on which the guide surfaces 109a, 109b, 109c are formed. The guide surface 109 d has an angle with respect to the central axis 110. One end portion 105 a of the push pin 105 is inserted and fixed in the groove portion 111 of the rotary core 101.

  As shown in FIG. 8, the fixed core 104 is formed in a cylindrical shape. Two cam protrusions 115 are provided on one end side of the fixed core 104 so as to protrude in the axial direction. The cam protrusion 115 is disposed so as to face the central axis 116 of the rotary core 101. On the cam projection 115, a guide surface 115a, a guide surface 115b, and a guide surface 115c are formed in the order toward the end. The guide surface 115 a and the guide surface 115 c are parallel to the central axis 116, and the guide surface 115 b has an angle with respect to the central axis 116. A guide surface 115d is formed on the cam projection 115 on the other side of the side where the guide surfaces 115a, 115b, and 115c are formed. The guide surface 115 d has an angle with respect to the central axis 116. The fixed core 104 is formed with an insertion hole 117 through which the push pin 105 is freely inserted.

  As shown in FIG. 9A, the rotating core 101 and the fixed core 104 are installed so that their cam protrusions are combined.

  Hereinafter, the operation of the above configuration will be described with reference to FIG. Here, for the sake of convenience, only the rotating core 101, the fixed core 104, and the push pin 105 are illustrated and described. FIGS. 9A, 9B, and 9C correspond to FIGS. 5A, 5B, and 5C of the first embodiment, respectively.

  When the mold opening is performed, the fixed-side template 6 (see FIG. 6) is released from the molded product 14. As shown in FIG. 9A, the rotating core 101 and the fixed core 104 are in a state of being closest to each other. The guide surface 109 a of the cam protrusion 109 is in contact with the guide surface 115 a of the cam protrusion 115.

  As shown in FIG. 9B, when the protruding plates 102 and 103 (see FIG. 6) are pressed, the guide surface 109a of the cam projection 109 slides on the guide surface 115a of the cam projection 115, and the rotary core 101 is moved. Slide and move in the protruding direction without rotating. The rotary core 101 moves to a position where the rotation operation is not interfered, that is, a position where the movement of the protrusion 108 is allowed.

  As shown in FIG. 9C, when the protruding plates 102 and 103 are further pressed, the guide surface 109b of the cam projection 109 slides on the guide surface 115b of the cam projection 115, and the rotary core 101 rotates. Move in the protruding direction. Thereby, the protrusion 108 of the rotary core 101 is released from the L-shaped protrusion 15 of the molded product 14 (see FIG. 6), that is, the undercut portion.

  After the molded product 14 is taken out, when the protruding plates 102 and 103 are moved in the return direction by the spring biasing force, the guide surface 109d of the cam projection 109 slides on the guide surface 115d of the cam projection 115 and rotates. The core 101 moves in the return direction while rotating in the reverse direction. Here, when the protrusion 108 of the rotating core 101 returns to the receiving portion 7a (see FIG. 4) of the core 7, the protrusion 108 and the receiving portion 7a are tapered. Positioned.

  By using the mold of the second embodiment, the same effect as when using the mold of the first embodiment can be obtained.

  Note that the cam protrusions formed on the rotating core and the fixed core are not limited to the above-described shape, as long as the cam protrusion is rotated after the rotating core is slid to a rotatable position.

  In the above-described embodiments (first and second embodiments), the ejector pin is used when the molded product is ejected after the mold is opened. However, only the rotating core may be ejected without using the ejector pin.

  In the above-described embodiment, the protruding plate and the cam mechanism are used as the rotating core displacing means. For example, the rotary core may be slid using a solenoid and then rotated using a motor.

  In the above embodiment, the present invention has been described using a general mold. However, the present invention can also be applied to a cassette mold as described in JP-A-9-155930. Since the present invention has a simple configuration, it can be easily incorporated into a cassette mold.

  In the above embodiment, the description has been given using the injection mold, but the present invention can also be applied to other molds for molding a molded product having an undercut portion, for example, a compression mold. .

It is a schematic sectional drawing of the metal mold | die for injection molding. It is an external appearance perspective view of a molded article. It is an external appearance perspective view of a rotation core. It is explanatory drawing explaining the taper of the protrusion of a rotation core. It is explanatory drawing explaining operation | movement when releasing the processus | protrusion of a rotary core from the undercut part of a molded article. It is a schematic sectional drawing of the metal mold | die for injection molding of 2nd Embodiment. It is an external appearance perspective view of a rotation core and an extrusion pin. It is an external appearance perspective view of a fixed core. It is explanatory drawing explaining operation | movement when releasing the processus | protrusion of a fixed core from the undercut part of a molded article.

Explanation of symbols

2,100 Injection mold 5 Cavity 6 Fixed side mold plate 7 Core 7a Receiving part 8, 101 Rotating core 14 Molded product 20 Movable side mold plate 25 Extrusion pin 26, 27 Extrusion plate 35, 108 Protrusion 37 Cam groove 37a First 1 groove part 37b 2nd groove part 102, 103 Ejection plate 104 Fixed core 105 Extrusion pin 109, 115 Cam protrusion

Claims (5)

In a mold for molding a molded product having an undercut part,
A pair of mold plates consisting of a fixed side and a movable side that are separated from each other when the mold is opened;
A rotating core that is mounted on the movable side template and has a portion for molding an undercut portion of the molded product,
Rotating core displacing means for rotating the rotating core after sliding the mold in the direction in which the molded product is projected after opening the mold, and releasing the part from the undercut portion of the molded product. Mold to be used. The rotating core is formed in a columnar shape,
The rotating core displacing means slides with respect to the movable side mold plate at the time of protruding the molded product and supports the rotating core rotatably.
A cam groove formed on a circumferential surface of the rotary core, and comprising a first groove parallel to the central axis of the rotary core and a second groove having an angle with respect to the central axis;
2. The mold according to claim 1, comprising a fixed pin that engages with the cam groove and is fixed to the movable side mold plate. The rotating core displacing means includes an ejection plate that slides with respect to the movable side mold plate when the molded product is ejected;
One end is fixed to the rotating core and the other end is rotatably supported by the protruding plate, and an extruding pin that pushes out the rotating core;
A fixed core that is inserted into the push pin to engage the rotating core and is fixed to the movable side mold plate;
A rotating core side cam portion formed on the rotating core;
2. The fixed core side cam portion formed on the fixed core and combined with the rotary core side cam portion to guide the rotary core side cam portion when the rotary core is pushed out. Mold.   The portion for molding the undercut portion of the molded product is tapered so that the cross-sectional width when cut along the central axis of the rotating core decreases toward the direction away from the fixed-side template, 4. The rotary core is positioned with respect to the movable side mold plate by using the taper when returning toward the movable side template after taking out the molded product. The mold according to claim 1. In a molding method for molding a molded product having an undercut portion using a mold,
A pair of stencils consisting of a fixed side and a movable side; a core mounted on the movable side stencil; a rotating core having a portion that constitutes a part of the core and forms an undercut portion of a molded product; The molten material is poured into the space formed by the cavity formed on the stationary side mold plate, and a molded product is formed.
After the mold opening, the rotary core is slid in the direction in which the molded product is projected and then rotated to release the part from the undercut portion of the molded product.

Images