JP6541466B2 - Injection molding equipment - Google Patents

Description

  The present invention relates to an injection molding apparatus, and more particularly to an injection molding apparatus suitable for releasing large resin parts such as automobile bumpers.

    In recent years, bumpers for automobiles tend to be integrally molded by injection molding as resin parts from the viewpoint of manufacturing cost and design freedom. Molded articles of this type are very large, and form a very complex three-dimensional shape from the viewpoint of safety and design. Therefore, in most cases, an extrusion pin is often provided in this type of injection molding apparatus for the purpose of reliably releasing the molded product from the molding die (see, for example, Patent Document 1). In this case, it is general to arrange an injection unit having a movable mold as a core and a fixed mold as a cavity, an extrusion mechanism having an extrusion pin on the core side, and an injection nozzle on the cavity side (for example, Patent Document 1, FIG. 4, paragraph 0027).

  As described above, in the molding die used for this type of molding apparatus, although it is general to arrange the extrusion mechanism and the injection unit in separate dies, the injection unit and the extrusion mechanism are separately provided. As a matter of course, when it is arranged in a mold, the injection molding apparatus itself becomes very large, which leads to an increase in the occupied space. In this case, the result contradicts the space saving of the facility, which is increasingly demanded in recent years, and it is necessary to immediately take measures to miniaturize the injection molding apparatus.

  Therefore, in order to solve the above-mentioned problems, the present inventors have proposed an injection molding apparatus capable of achieving both downsizing and improvement in releasability (see Patent Document 2). That is, this injection molding apparatus includes an extrusion mechanism disposed on the side of the core, and the extrusion mechanism has a plurality of elastic support portions elastically supported in a fixed mold, and the plurality of elastic support portions are At the time of mold clamping, by pushing into the cavity, the end face on the core side of the molded product is configured to be movable to a position that can be molded.

Unexamined-Japanese-Patent No. 2004-106220 JP, 2014-124931, A

  By the way, in large resin parts such as automobile bumpers, a portion (so-called undercut portion) having a negative angle with respect to the mold opening direction is often provided on the side of the cavity. As an example of the processing method of this undercut portion, for example, a structure in which negative angle processing is performed using a hydraulic cylinder before mold opening can be considered, but installation of the hydraulic cylinder or the like may lead to complication and enlargement of the mold. Yes, not preferable. Therefore, for example, a mechanism for pulling out the pin can be considered by sliding the pin for forming the undercut portion using a mold opening operation.

  Here, the operation of the pin drawing-out mechanism will be described based on the drawings together with the operation of the above-described extrusion mechanism. First, as shown in FIG. 6, at the time of molding (during mold clamping), the elastic support portion 42 pressed on the parting line PL of the cavity 12 is simultaneously restored by the elastic force of the elastic member 41 at the start of the mold opening operation. It starts to move in the mold release direction a (here, the same direction as the mold opening direction), and starts extruding the molded article 1 in the mold release direction a (see FIG. 8). Since this operation is a minute distance from the start of the mold opening operation, thereafter, as shown in FIG. 11, the molded article 1 maintains the state of being held on the side of the core 11 and continues the mold opening operation. Do. Accordingly, after the molded product 1 moves from the core 11 in the mold release direction a by a minute distance, it moves away from the cavity 12 while maintaining the positional relationship with the core 11 constant.

  On the other hand, as shown in FIG. 13 for example, the pin drawing out mechanism 150 causes the pin 151 which can be inserted into and ejected from the injection space 13 between the core 11 and the cavity 12 to project into the injection space 13 at the time of mold clamping. Then, the undercut portion 4 can be formed on the molded article 1. At this time, the pin 151 is integrally provided on the slide portion 153 elastically supported by the core 11 via the elastic member 152. Here, at the time of mold clamping, the slide portion 153 is pushed into the cavity 12 on the parting line PL, thereby moving the undercut portion 4 of the molded product 1 to a moldable position by the pin 151. The pin 151 can be moved from the undercut portion 4 of the molded article 1 in the direction b of pulling out by the restoring force of the elastic member 152.

  As described above, when the extrusion mechanism 40 having the elastic support portion 42 and the pin drawing mechanism 150 shown in FIG. 13 are adopted together with the injection molding apparatus, the molded article 1 is elastic at the same time as the mold opening operation starts. While the movement in the mold release direction a is started by being extruded to the support portion 42, the slide portion 153 which constitutes the pin pulling out mechanism 150 does not move in the mold release direction a with respect to the core 11, and It slides only in the direction of retracting from the cut portion 4 (in the direction b where the pin 151 is pulled out of the undercut portion 4). In this case, since the pin 151 and the undercut portion 4 interfere with each other (refer to FIG. 14), the mold opening operation is continued as it is, resulting in an unreasonable removal state, which is not acceptable to the undercut portion 4 of the molded article 1 in particular. There is a risk that scratches and deformation may remain.

  In view of the above-mentioned circumstances, in the present specification, even in the case of using an extrusion mechanism for extruding a molded product by an elastic support portion provided on the core side, the injection molding apparatus can be miniaturized and an undercut portion is achieved. It is the technical task to be solved to safely release the molded product without damaging the

  The solution to the above problems is achieved by the injection molding apparatus according to the present invention. That is, this apparatus comprises a core and a cavity, one of which is a fixed mold and the other of which is a movable mold, and an extrusion mechanism that extrudes a molded article formed between the core and the cavity by injection molding in a mold release direction by mold opening. In an injection molding apparatus provided with a pin drawing mechanism in which an undercut portion of a molded product is molded with a pin at the time of mold clamping and the pin is pulled out from the undercut portion with mold opening. The pin is integrally provided on the slide portion elastically supported on the side of the cavity, and the elastic support portion extrudes the molded product in the mold release direction simultaneously with the start of the mold opening operation. The movement of the orientation is initiated and the slide is characterized by the point of initiating the movement of the pin in the direction of withdrawal of the pin from the undercut.

  As described above, in the present invention, the elastic support portion of the extrusion mechanism is provided on the core side, and the pin for forming the undercut portion is integrally provided on the slide portion elastically supported on the cavity side, and the mold opening operation is performed. At the same time, the elastic support portion starts moving in the direction of pushing the molded product in the mold release direction, and the slide portion starts moving in the direction of pulling out the pin from the undercut portion. According to this structure, immediately after the start of the mold opening operation, the molded product moves in the mold release direction with respect to the core by the extrusion of the elastic support portion, while the slide portion of the pin drawing mechanism also separates from the core. While moving in the mold direction, the pin is moved in the direction of pulling out from the undercut portion (see FIG. 9 described later). As a result, interference between the pin and the undercut portion can be avoided, and the entire molded product can be safely released from the core while the pin is pulled out from the undercut portion. In addition, both the extrusion mechanism and the pin withdrawal mechanism are configured to operate the elastically supported members (elastic support portion, slide portion) using the clamping force, thereby simplifying the respective configurations and making the injection molding possible. It is possible to make the entire device compact.

  Also, when the molded product is a large resin part such as an automobile bumper, even if a part of the molded product is extruded in the mold release direction by the extrusion mechanism, it is still separated from the extrusion mechanism with the core. It is also conceivable that the close contact state has not been resolved. At this time, according to the pin drawing-out mechanism according to the present invention, the undercut portion of the molded product still in close contact with the core as the pin moves in the direction of releasing from the core immediately after the start of the mold opening operation. Engage and press the undercut portion in the mold release direction (see FIG. 10). As a result, the intimate contact between the undercut portion and the core is eliminated, and the effect of the undercut portion starting to move in the mold release direction following the main body of the molded article can also be expected. Therefore, the entire molded article can be reliably lifted up from the core, and smooth release operation can be achieved. Of course, at the stage where the mold opening operation has advanced to some extent, the pin is pulled out from the undercut portion with certainty, so the pin extrudes the undercut portion in the mold release direction more than the amount of extrusion of the molded product by the extrusion mechanism There is no concern that the parts will be damaged or deformed unnecessarily.

  As described above, according to the injection molding apparatus of the present invention, the injection molding apparatus can be miniaturized even if the extrusion mechanism for extruding a molded product is used by the elastic support portion provided on the core side. And, it becomes possible to release the molded article safely without damaging the undercut portion.

It is sectional drawing of the injection molding apparatus which concerns on one Embodiment of this invention. It is a front view of the injection molded article shape | molded by the injection molding apparatus shown in FIG. It is sectional drawing of the injection | spray nozzle mechanism of the injection molding apparatus shown in FIG. It is the figure which looked at the gate block which comprises the injection | emission nozzle mechanism shown in FIG. 3 from the nozzle side. It is sectional drawing of the injection | emission nozzle mechanism shown in FIG. It is sectional drawing of the extrusion mechanism of the injection molding apparatus shown in FIG. It is sectional drawing of the pin drawing-out mechanism of the injection molding apparatus shown in FIG. It is sectional drawing of the extrusion mechanism immediately after the start of mold opening operation. It is sectional drawing which shows the one aspect | mode of the pin drawing-out mechanism immediately after the start of type | mold opening operation | movement. It is sectional drawing which shows the other aspect of the pin drawing-out mechanism immediately after the start of type | mold opening operation | movement. It is sectional drawing of the extrusion mechanism after progress of die-opening operation | movement. It is sectional drawing of the pin drawing-out mechanism after progress of type | mold opening operation | movement. It is sectional drawing at the time of mold clamping of the pin drawing-out mechanism relevant to this invention. FIG. 14 is a cross-sectional view immediately after the start of the mold opening operation of the pin drawing out mechanism shown in FIG. 13;

  Hereinafter, an injection molding apparatus according to an embodiment of the present invention will be described based on FIGS. 1 to 12. Here, the case of injection molding an automobile bumper with the above-mentioned injection molding apparatus will be described as an example.

  FIG. 1 is a view showing an injection molding apparatus 10 according to an embodiment of the present invention. The injection molding apparatus 10 includes a core 11, a cavity 12, an injection space 13 formed between the core 11 and the cavity 12 at the time of mold clamping, and an injection unit 20 for injecting and supplying a molten resin to the injection space 13. A gate block 30 disposed between the injection space 13 and the injection unit 20, an extrusion mechanism 40 for extruding the molded article 1 (see FIG. 2) in the mold release direction a with mold opening, and the molded article 1 And a pin extraction mechanism 50 for extracting the pin 51 from the undercut portion 4 of FIG.

  Here, the pushing mechanism 40 is disposed on the side of the core 11, and the pin drawing mechanism 50 is disposed on the side of the cavity 12. In the present embodiment, both the injection unit 20 and the gate block 30 are disposed on the side of the cavity 12. Further, in the present embodiment, the core 11 is a fixed type and the cavity 12 is a movable type. Therefore, in this case, the injection unit 20, the gate block 30, and the pin drawing mechanism 50 move integrally with the cavity 12 in the mold release direction a, and the pushing mechanism 40 is always fixed.

  The injection unit 20 is, as shown in FIG. 3, an injection machine 21, a hot runner 22 for supplying the molten resin injected from the injection machine 21 to the injection space 13, and a tip of the hot runner 22 integrally or separately. The valve pin 25 for opening and closing the nozzle portion 23 by inserting or removing it from the nozzle portion 23 provided on the side, the band heater 24 disposed around the hot runner 22, and the inner periphery of the nozzle portion 23. And.

  The gate block 30 defines a part of the injection space 13 and abuts on the nozzle portion 23 of the injection unit 20 to constitute an injection gate mechanism. Specifically, as shown in FIG. 3, the gate block 30 is opened at the nozzle abutment surface 31 that allows the nozzle portion 23 of the ejection unit 20 to abut, and the nozzle abutment surface 31 and is adjacent to the ejection space 13 And a gate 32. In the present embodiment, the gate 32 has a shape corresponding to the rib 2 (broken line in FIG. 2) erected on the back surface of the molded product 1 and is disposed at one or more locations adjacent to the injection space 13 Be done. Here, as shown in FIG. 2, the shape and arrangement of the gate 32 so that the rib 2 is erected on the back surface 1b along the character line 1c formed on the surface 1a of the molded product 1 to be the design surface. The setting position is set.

  Further, when viewed in relation to the nozzle portion 23, the thickness dimension of the gate 32 is smaller than the opening diameter of the nozzle portion 23 as shown in FIG. 4, and the longitudinal dimension thereof is the outer diameter of the nozzle portion 23. Greater than. In other words, the rib-shaped gate 32 extends in the diameter direction of the nozzle portion 23 beyond the outer peripheral surface position of the nozzle portion 23. Further, as shown in FIG. 5, this gate 32 has a flat contact portion with the nozzle portion 23, and the height of the standing from the back surface of the rib 2 gradually decreases toward both sides in the longitudinal direction It has a shape.

  As shown in FIG. 6, the pushing mechanism 40 has a plurality of elastic support portions 42 elastically supported by the core 11 via an elastic member 41 such as a spring. The elastic support portion 42 has a mold contact surface 43 in contact with the cavity 12 and a molding surface 44 for molding the surface of the molded product 1 (here, for example, the end surface 1 d shown in FIG. 8). Then, at the time of mold clamping, by being pushed into the cavity 12, the elastic support portion 42 is moved to a position where the end face 1d of the molded product 1 can be molded (a position shown in FIG. 6). In this state, the elastic support portion 42 receives an urging force (elastic restoring force) from the elastic member 41 in the releasing direction a. A guide surface 15 (for example, a tapered surface as illustrated) for guiding the outer surface of the elastic support portion 42 in the mold release direction a is formed in the accommodation hole 14 of the core 11 for accommodating the elastic support portion 42. At the same time, the elastic support portion 42 is made movable in the mold release direction a while maintaining the contact state with the end face 1 d of the molded article 1. At this time, the rigidity (elastic coefficient) of the elastic member 41 is equal to or less than the extent to which the elastic support portion 42 can move the end face 1 d to a position where the end face 1 d can be formed by pushing the cavity 12 accompanying the clamping operation. It is preferable that the size is set and set to a size that can partially cancel the adhesion of the molded product 1 to the core 11 by the elastic restoring force stored at the time of mold clamping.

  In the present embodiment, at least a portion of the plurality of elastic support portions 42 is formed around the opening such as the grille portion 3 (FIG. 2) formed in the molded product 1 by pressing by the cavity 12 at the time of mold clamping. The end face including the end face is disposed at a position where the end face in the opposite direction to the mold opening direction in the peripheral portion of the molded article 1 can be formed. In this illustrated example, the shape and size thereof are set such that the end face 1 d provided at the lower end of the molded product 1 can be pushed out by one elastic support portion 42 (the molding surface 44).

  As shown in FIG. 7, the pin drawing-out mechanism 50 forms the molded article 1 in the injection space 13 by causing the pin 51 which can be inserted into the injection space 13 to protrude into the injection space 13 at the time of mold clamping. At the same time, the molded product 1 is a mechanism for molding the undercut portion 4 located closer to the cavity 12 than the parting line PL between the core 11 and the cavity 12. More specifically, the pin drawing-out mechanism 50 is elastically supported by the cavity 12 through the elastic member 52, and in a direction intersecting the mold opening direction with the mold opening operation (in the embodiment, the direction orthogonal to the mold release direction a) The slide unit 53 slides on the A pin 51 is integrally provided at one end (the lower end in FIG. 7) of the slide portion 53 in the sliding direction. Further, a cam surface 54 engaged with the core 11 is provided at the other longitudinal end (upper end in FIG. 7) of the slide portion 53 on the opposite side to the pin 51. Then, when the cam surface 54 is pressed into the core 11 at the time of mold clamping, the pin 51 protrudes into the injection space 13 and the engagement between the cam surface 54 and the core 11 is released as the mold opens. The sliding portion 53 can move the pin 51 from the undercut portion 4 of the molded article 1 in the direction b of pulling out by the elastic restoring force stored in the elastic member 52 (see FIG. 10 etc. described later). In this embodiment, as a mechanism for pulling out the pin 51 for forming the hole as the undercut portion 4 in the ridge portion standing on the back surface 1b side in the upper end portion (upper side in FIG. 2) of the molded product 1 , And a pin pullout mechanism 50 is provided.

  Hereinafter, an example of the injection molding method using the injection molding apparatus 10 of the said structure is mainly demonstrated based on FIGS. 6-12.

  First, as shown in FIG. 1, the molten resin is supplied to the injection space 13 by the injection unit 20 in a state where the cavity 12 as a movable mold is brought close to the core 11 and clamped. At this time, as shown in FIG. 3, the molten resin is injected and supplied into the injection space 13 through the rib-shaped gate 32 provided on the gate block 30 in contact with the nozzle portion 23 of the injection unit 20. . Thereby, the injection space 13 and the gate 32 are filled with the molten resin. Then, the valve pin 25 is fitted to the nozzle portion 23 to cool the filled molten resin in a state where the nozzle portion 23 is closed, whereby the molten resin is solidified, for example, a molded article 1 having a shape shown in FIG. (Bumper for automobile) is molded. At this time, since the molten resin filled in the gate 32 having a rib shape continuously with the main body of the molded article 1 is also integrally molded, as shown in FIG. Are integrally formed in a standing condition. Further, an undercut portion 4 (hole) vertically penetrating through the flange portion is formed by a pin 51 projected from the upper end portion of the molded product 1 to the back surface 1b side by a pin 51 projected into the injection space 13 It is integrally formed with 1 (FIG. 2, FIG. 7).

  Thus, after the injection molding of the molded article 1 is completed, a mold opening operation for moving the cavity 12 away from the core 11 is started, and the molded article 1 is released and taken out. Here, the core 11 is provided with a plurality of elastic support portions 42 as the extrusion mechanism 40 of the molded product 1. Then, as shown in FIG. 8, with the start of the mold opening operation, the cavity 12 moves away from the elastic support portion 42 in the direction away from the elastic support portion 42 (here, the mold release direction a), thereby being stored in the elastic member 41 at the time of mold clamping. The elastic restoring force is released, and the restoring force is applied to each elastic support portion 42 as a biasing force in the mold release direction a. As a result, each elastic support portion 42 presses the end face 1 d of the molded article 1 in the mold release direction a, and at least the peripheral part of the end face 1 d of the molded article 1 floats up from the core 11 (FIG. 8).

  On the other hand, since the pin drawing-out mechanism 50 is provided on the side of the cavity 12, with the start of the mold opening operation, movement with the cavity 12 is started in the mold release direction a (see FIG. 9). Further, when the pushing state of the cam surface 54 by the core 11 is released, the slide portion 53 elastically supported by the cavity 12 starts to move the pin 51 from the undercut portion 4 in the direction b (FIG. 9) . Here, as described above, when the entire molded product 1 moves in the mold release direction a by the plurality of elastic support portions 42 pushing the molded product 1 in the mold release direction a, the molded product 1 is formed. The undercut portion 4 also starts moving in the mold release direction a, but the slide portion 53 integrally provided with the pin 51 also starts moving in the mold release direction a together with the cavity 12 (FIG. 9) The pin 51 gradually moves in the pulling direction b without interference with the undercut portion 4.

  Alternatively, although the plurality of elastic support portions 42 extrude the molded product 1 in the mold release direction a, a portion far away from the installation location of the extrusion mechanism 50 (for example, the undercut portion on the upper part of the molded product 1 shown in FIG. When 4) still maintains the close contact with the core 11, the undercut portion 4 remains at the same position as at the time of mold clamping even immediately after the start of the mold opening operation. Here, since the slide portion 53 in which the pin 51 is integrally provided starts to move in the mold release direction a together with the cavity 12, as shown in FIG. It engages in the mold release direction a, and while moving the undercut portion 4 in the mold release direction a, it gradually moves in the pull direction b. Therefore, the intimate contact state between the undercut portion 4 or its peripheral portion and the core 11 is eliminated, and the undercut portion 4 or its peripheral portion starts moving in the mold release direction a following the molded product 1 (FIG. 10). ).

  Then, for example, after the time when the pin 51 is completely pulled out from the undercut portion 4, the extrusion operation of the molded article 1 by the elastic support portion 42 is completed, and then only the pin drawing mechanism 50 provided in the cavity 12 and the cavity 12 Continues to move in the mold release direction a. In other words, when the extruding operation of the molded article 1 by the elastic support portion 42 is completed, when the pin 51 is completely pulled out from the undercut portion 4, the cavity 12 and the pin pulling out mechanism 50 do not interfere with each other. The movement is continued in the direction away from the core 11 and the molded article 1 without being generated. During this time, the molded product 1 does not move from the position shown in FIG. 8, and the positional relationship with the core 11 is kept constant (see FIG. 11). Further, the pin drawing mechanism 50 moves to a position at a sufficient distance from the core 11 and the molded article 1 while maintaining the state in which the pin 51 is completely drawn from the undercut portion 4 as the mold opens. (See Figure 12). Thus, the cavity 12 is stopped at a stage where a gap sufficient to take out the molded product 1 is formed between the core 11 and the cavity 12, and from this state, for example, the transfer means such as a material hand is used as the core 11 and The molded article 1 is taken out from the inside of the injection molding apparatus 10 by inserting it into the cavity 12 and holding the molded article 1. Thereby, the release operation of the molded article 1 is completed.

  Thus, in the injection molding apparatus 10 according to the present invention, the elastic support portion 42 of the extrusion mechanism 40 is provided on the core 11 side, and the pin 51 for forming the undercut portion 4 is elastically supported on the cavity 12 side. The elastic support portion 42 starts moving in the direction of extruding the molded product 1 in the mold release direction a simultaneously with the start of the mold opening operation, and the slide portion 53 is an undercut portion 4. The movement of the direction b from which the pin 51 is pulled out is started. According to this structure, immediately after the start of the mold opening operation, the molded product 1 moves in the mold release direction a with respect to the core 11 by the extrusion of the elastic support portion 42, while the slide portion 53 of the pin drawing mechanism 50 also While moving in the mold release direction a with respect to the core 11, the pin 51 is moved in the direction b from which the undercut portion 4 is pulled (FIGS. 8 and 9). Thereby, even when the undercut portion 4 remains on the side of the cavity 12 beyond the parting line PL, the interference between the pin 51 and the undercut portion 4 is avoided, and the pin 51 is pulled out from the undercut portion 4 The entire molded article 1 can be safely released from the core 11. In addition, both the extrusion mechanism 40 and the pin withdrawal mechanism 50 are configured to operate the elastically supported members (elastic support portion 42, slide portion 53) using the clamping force, thereby simplifying the respective configurations. Thus, the entire injection molding apparatus 10 can be made compact.

  In the case where the molded product 1 is a large-sized resin component such as an automobile bumper as in the present embodiment, a part of the molded product 1 is extruded in the mold release direction a by the plurality of extrusion mechanisms 50. Also, it is conceivable that the adhesion state with the core 11 is not canceled yet at the part separated from the pushing mechanism 50, such as the undercut part 4, and the part remains at the mold clamping position (for example, the position shown in FIG. 7). Even in this case, according to the pin drawing-out mechanism 50 according to the present invention, the pin 51 still moves closely to the mold release direction a from the core 11 immediately after the start of the mold opening operation, so the core 11 still adheres. The undercut portion 4 is engaged with the undercut portion 4 of the molded product 1 in the state, and the undercut portion 4 is pressed in the mold release direction a. As a result, the adhesion between the undercut portion 4 and the core 11 is eliminated, and the effect of the undercut portion 4 starting to move in the mold release direction a following the main body of the molded article 1 can also be expected. Therefore, the entire molded article 1 can be reliably lifted up from the core 11, and smooth release operation can be achieved. Of course, at the stage where the mold opening operation has advanced to a certain extent, the pin 51 is pulled out of the undercut portion 4 with certainty. Therefore, the pin 51 releases the undercut portion 4 more than the amount of extrusion of the molded product 1 by the extrusion mechanism 50 There is no concern that the undercut portion 4 may be damaged or deformed unnecessarily.

  As mentioned above, although one embodiment of the present invention was described, the present invention can also adopt composition other than the above in the range which does not deviate from the meaning.

  For example, although the case where the core 11 is a fixed type and the cavity 12 is a movable type is illustrated in the above embodiment, it is of course possible to apply the present invention to the case where the configuration is reversed. That is, even when the core 11 is a movable type and the cavity 12 is a fixed type, the undercut portion 4 can be provided by providing the extrusion mechanism 50 according to the present invention on the core 11 side and the pin drawing mechanism 50 on the cavity 12 side. Safe removal of the molded article 1 including

  Moreover, although the case where the bumper for motor vehicles was shape | molded as the molded article 1 was illustrated in the above description, of course, this invention is applicable also to injection molding of the molded article other than this. That is, the invention can be applied to various resin parts such as exterior parts such as bumpers and interior parts such as instrument panels. Of course, it is possible to apply not only to large parts but also to small parts.

DESCRIPTION OF SYMBOLS 1 Molded product 1 d End face 2 Rib 3 Grille part 4 Undercut part 10 Injection molding device 11 Core 12 Cavity 13 Injection space 14 Housing hole 15 Guide surface 20 Injection unit 21 Injection machine 22 Hot runner 30 Gate block 32 Gate 40 Extrusion mechanism 41 Elasticity Member 42 elastic support portion 43 mold contact surface 44 molding surface 50 pin extraction mechanism 51 pin 52 elastic member 53 slide portion 54 cam surface 150 structure 151 pin 152 elastic member 153 slide portion a release direction b pin extraction direction PL parting line

Claims (1)

A core and a cavity, one of which is a fixed mold and the other of which is a movable mold, an injection space formed between the core and the cavity at the time of mold clamping , and a molded article formed in the injection space by injection molding a pushing mechanism for pushing in the release direction by, during the mold clamping, molding the undercut portion of the molded article with a pin, with the mold opening comprises a pin withdrawal mechanism to pull the pin from the undercut portion In the injection molding apparatus
The extrusion mechanism has an elastic support portion elastically supported on the side of the core,
The pin is integrally provided on a slide portion elastically supported on the side of the cavity,
At the same time as the start of the mold opening operation, the elastic support portion starts moving in a direction for pushing the molded product in the releasing direction, and the slide portion starts moving in a direction for pulling out the pin from the undercut portion. An injection molding apparatus characterized by

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