JPH08267520A - Injection mold assembly - Google Patents

Abstract

PURPOSE: To easily unload a molded resin product from a mold without damaging or deforming an undercut part. CONSTITUTION: An injection mold assembly 10 for molding a resin product having an undercut part is equipped with a pair of molds consisting of a fixed mold 11 and a movable mold 12, both of which can be opened and closed each other, an extruding core 15 for forming the undercut part of the resin product, which is elastically and biforkedly openably split by a slit 16 and, at the same time, which is provided extrudably in the mold opening and closing direction Z in the mold 12 and an extruding core biforkedly opening means 20 for biforkedly opening the extruding core 15 by pushing open the split 16. Since the extruding core 15 is biforkedly opened by the means 20 at extrusion, the undercut part is released from the extruding core 15 without being damaged and deformed, a product can easily be unloaded from the molds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die apparatus, and more particularly to an injection molding die apparatus for molding a resin product having an undercut portion.

[0002]

2. Description of the Related Art In an injection molding die apparatus for molding a resin product by injection molding, an undercut portion of the resin product, that is, a portion forming a negative angle with respect to a die opening direction of the die is formed. When it has, it is necessary to consider the die cutting process (undercut process) for the undercut portion.

FIG. 6 is a cross-sectional view showing an example of a resin product having such an undercut portion, showing a garnish used in a sliding roof of an automobile or the like in a cross section. Further, FIG. 7 is a perspective cross-sectional view showing a cross section taken along line XX of FIG. 6 when viewed obliquely.

As shown in FIGS. 6 and 7, a garnish indicated by 1 as a whole is formed in an elongated shape along a holding frame of a sliding roof, and its main body portion 1a has a design surface as an outer side in a cross section. It is formed in a substantially U shape. Then, inside the main body portion 1a, mounting claw portions 1b for mounting to the roof panel are provided at a number of locations at regular intervals in the longitudinal direction thereof (in FIGS. Only one place is shown). This mounting claw 1b
Is formed as a claw-shaped piece having a width m in the lengthwise direction of the main body portion 1a so as to project substantially at a right angle thereto, and an engaging portion is formed in a step shape on one side thereof. Therefore, the mounting claw portion 1b forms an undercut portion that becomes a catch in the mold opening direction of the mold, that is, in the mold opening / closing direction Z.

In the case of the garnish 1 having the mounting claw portion 1b forming such an undercut portion, the undercut treatment can be relatively easily performed by using the inclined slide extrusion core. That is, conventionally, the movable core of the injection molding die device is slidably assembled in a slanted state with the extrusion core forming the surface of the mounting claw 1b on the side having the undercut, and the product after the mold is opened. At the time of extrusion, the undercut treatment was performed by tilting the extrusion core so as to move in the direction perpendicular to the mold opening direction (to the right in FIG. 6) by the height of the undercut. Regarding the undercut process using such an inclined slide extrusion core, the specific shape of the undercut portion is different, but disclosed in, for example, Japanese Patent Application Laid-Open Nos. 4-189521 and 6-71703. Has been done.

Incidentally, in addition to the use of the inclined slide extrusion core which is movable obliquely with respect to the mold opening / closing direction Z, Japanese Patent Publication No. 1-59897 discloses a mold opening / closing direction Z.
A similar moveable extruded core is disclosed. More specifically, the extruded core includes a plurality of core blocks (extruded cores 16) that jointly define a cavity for forming an undercut portion (protrusion 10a) of a resin product, and each core block. An elastic support member (leaf spring 18) that is independently connected to the core push-out pin (17) is provided, and the movable side mold has a mold opening / closing direction Z.
Is extrudable. Then, in this injection molding die device, when the product is extruded after the mold is opened, the extruding core is extruded together with the ejector pin (extruding pin 15), then the extruding of the extruding core is stopped, and only the ejector pin is extruded. . As a result, the molded product is extruded together with the undercut portion, at which time the undercut portion opens the core block connected to each elastic supporting member against the elasticity and separates from the core block. . This publication also discloses a modification in which those supporting members are leaf springs that urge the core block to automatically open when the extruded core is extruded.

[0007]

FIG. 8 is a sectional view showing another garnish in which the shape of the mounting claw portion is different from that in FIGS. 6 and 7.

By the way, the garnish 1 shown in FIGS.
In this case, the mounting is performed by once mounting a metal clip on the mounting claw portion 1b and then assembling this to a roof panel or the like. Therefore, a metal clip is required as a separate component, and its attachment is troublesome. Therefore, it is considered to change the mounting claw 1b to obtain the mounting claw 1c as shown in FIG. That is, the mounting claw portion 1c is a pair of claw-shaped pieces 1d corresponding to the mounting claw portion 1b of FIGS. 6 and 7, and a space portion (meat steal portion) 1e for allowing elastic deformation therebetween. It corresponds to a space that is opposed to each other (therefore, each claw-shaped piece 1 of this mounting claw 1c
The planar shape of d is the same as that in FIG. 7), and the clip is formed by itself. Therefore, according to the mounting claw portion 1c, the garnish 1 can be directly assembled to the roof panel or the like without a metal clip.

However, such a pair of claw-shaped pieces 1
In the case of the mounting claw portion 1c made of d, the undercuts that form the engagement portion are provided on both sides thereof (outside each claw-shaped piece 1d), so that the undercut process becomes a problem.
That is, when the mounting claw portion 1c is formed by the slant slide extrusion core as in the conventional case, the slant slide extrusion cores that form the undercuts on both sides of the attachment slide claw portion of the claw portion 1c are extruded when the product after molding is extruded. It must be die-cut in the width direction (left-right direction in FIG. 7). That is, the inclined slide extrusion core has at least the width m of the mounting claw portion 1c (see FIG.
It is necessary to operate so as to move in the width direction by a distance corresponding to the width m) of the mounting claw portion 1b in FIG.

Such an undercut process is extremely difficult because it is not possible to provide a draft in the width direction on the mounting claw portion 1c itself which constitutes the undercut portion. Further, also in the die manufacturing, it is difficult to process the slide surface for guiding the inclined slide extrusion core so that the inclined slide extrusion core operates accurately in synchronization with the operation of the ejector pin, because it is taper processing. It is accompanied. Therefore, in the undercut process using this inclined slide extrusion core, it is impossible to perform die cutting because it is difficult to obtain the machining accuracy of the die.
There is a risk that the c or the main body portion 1a may be deformed or damaged.

Further, in this undercut processing,
The inclined slide extrusion core has to move a long distance in order to be die-cut from the mounting claw 1c.
A large space is required around the. However, depending on the specific product shape, reinforcing ribs or other bosses or walls may be set near the mounting claws 1c. Therefore, when such a rib or the like is set within the operating range of the inclined slide extrusion core, there is a problem that the inclined slide extrusion core itself cannot be applied.

Regarding this point, the above-mentioned Japanese Patent Publication No. 1
According to the technique disclosed in JP-A-59897, the extrusion core is extruded in the mold opening direction of the mold and is divided into a plurality of core blocks so that the legs can be opened. In the case of a section, the undercut process can be performed in a small space by opening the core block at right angles (in the left-right direction in FIG. 8) to the width direction of the mounting claw 1c. However, in the case of this extrudable core capable of opening legs, it is necessary that the elasticity of the support member is sufficiently high for the core block to be stably supported. Since this is done against the elasticity of the undercut, the undercut portion may be damaged during the die cutting. It should be noted that if this support member is pre-biased so as to open the legs during extrusion, this will not occur, but in that case, the extrusion core and the concave portion of the mold that houses the extrusion core always have a strong elastic force. They come into abutment and can themselves damage or wear each other. Further, this extruded core is one in which the core block, the support member and the core extruding pin are mutually coupled and assembled, so that it takes time and cost to manufacture and it is difficult to obtain accuracy.

As described above, in the case of the garnish 1 having the mounting claw portions 1c having undercuts on both sides, the undercut portion is not damaged or deformed by the conventionally known undercut processing means. It was difficult to die-cut.

Therefore, an object of the present invention is to provide an injection molding die apparatus which can easily take out a resin product after molding without damaging or deforming the undercut portion. .

[0015]

SUMMARY OF THE INVENTION An injection molding die device according to the present invention is an injection molding die device for molding a resin product having an undercut portion. A pair of molds including a mold and an extrusion core that forms the undercut portion, which are split and formed elastically by a slit so that the legs can be opened, and can be extruded into the mold in the mold opening / closing direction. It is provided with an extruded core provided and an extruded core leg opening means for expanding the slit to open the extruded core when the extruded core is extruded from the mold.

[0016]

In the injection molding die apparatus according to the present invention,
After clamping a pair of molds consisting of a movable mold and a fixed mold, the molten resin material is injected into the product cavity formed by them, and the pressure is appropriately maintained, followed by the usual process of solidifying by cooling. , A resin product is molded. Further, in this case, the undercut portion of the resin product is also molded by the extrusion core forming the undercut portion.

The molded resin product is taken out by opening the pair of molds and then extruding the extrusion core in the mold opening / closing direction to release the resin product from the mold and the extrusion core. It is done by letting. At the time of this extrusion, the extrusion core forming the undercut portion of the resin product is divided and formed elastically by the slit so that the extrusion core can be opened and the extrusion core is opened to open the extrusion core. Since the leg means is provided, the extrusion core is opened by the extrusion core opening means and removed from the undercut portion.

In this way, the die cutting of the extrusion core from the undercut portion is performed by opening the extrusion core by the extrusion core opening means, so that the undercut is attached on both sides as shown in FIG. Even in the case of the claw portion 1c, the extrusion core can be easily die-cut by opening the extrusion core in both lateral directions (left and right directions in FIG. 8) by the height of the undercut, and at this time, No excessive force is applied to the undercut part. That is, the resin product after molding can be easily taken out without damaging or deforming the undercut portion.

[0019]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing a main part of an injection molding die apparatus according to an embodiment of the present invention. 2 is a cross-sectional view showing the essential parts of the movable mold shown in FIG. 1 in a further enlarged manner, and FIG. 3 is a plan view showing the essential parts of the movable mold shown in FIG. 2 corresponds to the sectional view taken along the line AA of FIG. 3.)
Further, FIGS. 4 and 5 are sectional views showing the state of the resin product after molding at the time of extrusion, FIG. 4 is a sectional view showing the state at the intermediate stage of extrusion, and FIG. 5 shows the state at the end of extrusion. It is sectional drawing shown.

This injection molding die apparatus is applied to the injection molding of a resin product having an undercut portion,
Specifically, it is embodied as a device for molding the garnish 1 having the mounting claw portion 1c shown in FIG.

As shown in FIG. 1, the injection molding die apparatus of the present embodiment, which is generally designated by 10, is similar to a conventional die apparatus of this type. Mold 12
It has and. That is, the pair of molds 11 and 12
Can be clamped together in the mold opening / closing direction Z to open the mold,
When the mold is clamped, the product cavity c corresponding to the garnish 1 is jointly formed. And fixed side mold 11
In order to inject the molten resin material into the cavity c, a gate, a sprue, a runner, etc., which are not shown, are formed in the. Further, the movable side mold 12 is specifically, a movable side mold plate 13 and a product part insertion piece 1 that is integrally coupled to the movable side mold plate 13 and forms a core surface of a product cavity c.
And 4 are formed.

Here, the injection mold apparatus 10 of the present embodiment.
In order to form the mounting claw portion 1c of the garnish 1 that forms the undercut portion, the movable mold 12 is provided with the elastically openable extruded core 15 whose tip portion is divided by the slit 16. It is provided so as to be extrudable in the mold opening / closing direction Z by being guided by a guide hole 17 formed through the movable side mold plate 13 and the product part insertion piece 14.
Then, the rear end of the extrusion core 15 is interlocked with the movable side mold 12 or by a separate actuator, in the mold opening / closing direction Z.
The ejector plate 18 is operated by a bolt 19. Therefore, the extrusion core 15 is extruded from the position where the tip of the extrusion core 15 coincides with the core surface of the product part insertion piece 14 until the ejector plate 18 comes into contact with the movable side metal plate 13, that is, for the extrusion stroke s. Further, in the movable side mold 12, the slit 16 of the extrusion core 15 is spread to open the extrusion core 15, and the attachment claw portion 1c is formed in cooperation with the extrusion core 15 and the product portion insertion piece 14. An insert core 20 which forms a part of the core surface is fixedly attached to the product portion insertion piece 14 by a bolt 21.

The shapes and structures of these extruded core 15 and insert core 20 are shown in more detail in FIGS. Note that FIG. 2 shows a state when the mold is opened after molding, and therefore the molded garnish 1 is also shown.

As shown in FIGS. 2 and 3, the extruded core 15 formed of a single rod-shaped member is made of a metal material having a relatively high toughness, and a certain range on the tip side is formed by a slit 16. It is formed as having a pair of extruded core leg pieces 15a that are split and thereby elastically open each other. And each extruded core leg piece 15
The tip of a is the undercut surface on both sides of the mounting claw 1c,
That is, it is formed as an undercut forming portion 15b having a carving corresponding to the outer surface of each claw-shaped piece 1d. Therefore, these opposing undercut forming portions 15b form the surfaces on both sides of the mounting claw portion 1c that undercut in the mold opening / closing direction Z.

Also, the pair of extruded core leg pieces 15a.
When the extrusion core 15 is extruded, the slit 16 is opened and opened. Therefore, this extruded core 15
In order to allow or smooth the spread of the legs, the guide hole 17 for guiding the same in the mold opening / closing direction Z has a side surface on the side of the opening in the opening 17a extending over a certain depth range. Taper is formed. Corresponding to this taper, each extruded core leg piece 15a of the extruded core 15 is also formed with a tapered outer surface at the tip portion (FIG. 2). Since the tip end portion of the extruding core 15 has a taper shape that widens toward the tip end side as described above, its retreat is restricted, and when the extruding core 15 is most retracted and is not extruding, the extruding core 15 has a taper tip end. Part is guide hole 17
Is close to the opening 17a. And the extruded core 15
The tip of the is aligned with the core surface of the product part insertion piece 14 when it is not extruded, and forms a continuous flat surface.

More specifically, the slit 16 is formed in the same width as the straight portion 16a within a certain length range from the tip, and is formed as the tapered portion 16b so that the width gradually decreases thereafter. And stress relief hole 1
It is terminated at 6c.

The extrusion core opening means for expanding the slit 16 to open the extrusion core 15 is formed as an insert core 20 in this embodiment. This insert core 20 is attached to the movable mold 12 by the bolt 2
1. A fixed base portion 20a fixedly attached by 1, a widened portion 20b protruding into the guide hole 17 and arranged in the slit 16 of the extrusion core 15, and a core portion 20c integral with the widened portion 20b. There is. Specifically, the fixed base 2
0a is formed in a shape corresponding to the accommodating recess 14a formed in the product part insertion piece 14, and when it is fitted into this accommodating recess 14a and then fixed by the bolt 21, the surface thereof is the product part insertion piece 14a. It is formed so as to form a core surface continuous with the surface. Therefore, the insert core 20
After the extruded core 15 is inserted into the guide hole 17 and assembled, the fixed base portion 20a is fitted into the accommodating recess 14a and then the bolt 21 is tightened, so that the movable side die 12 is easily assembled from the front surface side. , It can be fixed again.

The expanded portion 20b and the core portion 20c are formed so as to protrude from the fixed base portion 20a into the guide hole 17 by the length corresponding to the width thereof, and are arranged in the slit 16 of the extrusion core 15. The widened portion 20b is formed as a wedge-shaped portion having a thickness equal to the width of the straight portion 16a of the slit 16 in this embodiment. Therefore, in the process of extruding the extruded core 15, the expanded portion 20b simply slides in the range of the straight portion 16a, but acts as a wedge in the tapered portion 16b to spread the slit 16. The pair of extrusion core leg pieces 15a of the extrusion core 15 are opened. Further, the core portion 20c provides a core surface for forming the space portion 1e (FIG. 8) of the mounting claw portion 1c. Therefore, the pair of undercut forming portions 15 b of the extrusion core 15 and the insert core 20
This core portion 20c is the opening portion 17a of the guide hole 17.
A cavity for forming the whole of the mounting claw portion 1c of the garnish 1 is defined in cooperation with the side surface of the above.

The extruding core 15 and the insert core 20 are formed in this way, and are respectively provided at the positions where the mounting claws 1c of the movable die 12 are to be formed. And
In the injection molding die apparatus 10 of the present embodiment for molding the garnish 1 having many mounting claws 1c, a large number of extrusion cores 15 are provided accordingly, and therefore it is generally used for extruding products after molding. No ejector pin (protruding pin) is provided. However, the further provision of the ejector pin can be appropriately performed as necessary in order to equalize and disperse the pushing force. In this case, the ejector pin may be connected to the ejector plate 18 to operate with the extrusion core 15, or may be connected to another ejector plate or the like to operate independently of the extrusion core 15.

Molding of the garnish 1 by the injection molding die apparatus 10 of this embodiment is the same as the usual case. That is, after the fixed side mold 11 and the movable side mold 12 are clamped as shown in FIG. 1, the molten resin material is supplied to the product cavity c formed by these, and the pressure is appropriately maintained and cooled. The garnish 1 is molded as shown in FIG. In this case, the ejector plate 18 is most retracted with respect to the movable-side metal plate 13, and the extruding core 15 is positioned so that the tip thereof coincides with the core surface of the movable-side mold 12 (product part insertion piece 14). . The molten resin material is also filled in the cavity defined by the pair of undercut forming portions 15b of the extruded core 15, the core portion 20c of the insert core 20, and the side surface of the opening 17a of the guide hole 17. Then, the mounting claw portion 1c of the garnish 1 is molded at the same time.

The garnish 1 thus formed is taken out by extruding the extrusion core 15 as follows. 2, FIG. 4, and FIG. 5 sequentially show the process of extruding the extruded core 15.

First, the movable mold 12 is moved in the mold opening / closing direction Z to open the mold. This state is shown in FIG. 2, in which the stationary mold 11 is released from the molded garnish 1,
The movable side mold 12 is separated from the surface side by a sufficient distance. Then, in this state in which the mold has been sufficiently opened, the ejector plate 18 is operated toward the movable-side metal plate 13 to extrude the extrusion core 15 from the surface of the movable-side mold 12. At this time, the extrusion core 15 has a guide hole 17 formed in the mold opening / closing direction Z.
Since it is guided by, it is extruded in the mold opening / closing direction Z. The operation of the ejector plate 18 is the same as the case of the push-out by the ejector pin, and by pressing the ejector plate 18 against the moving movable die 12, or by using a separate actuator or the like. It can be performed appropriately.

The garnish 1 formed by extruding the extruded core 15 from the movable die 12 is
The mounting claw portion 1c that engages with or abuts the extrusion core 15
The lower surface of the main body portion 1a is lifted, and is separated from the core surface of the product portion insert piece 14 of the movable die 12 and the core portion 20c of the insert core 20. Further, in this case, in the first certain range of the process in which the extrusion core 15 is extruded, the slit 16 is
Since the width of the straight portion 16a is formed to be equal to the thickness of the expanded portion 20b of the insert core 20, the extrusion core 15 is extruded as it is without being opened. This state is shown in FIG. 4, and the garnish 1 after molding has the mounting claw portion 1c.
Is held by the extruding core 15, and is lifted from the core surface of the product portion insertion piece 14 by the length of the straight portion 16a. Therefore, by extruding the extruding core 15 in this way, not only the extruding operation is smoothly performed, but also the garnish 1 after molding is not subjected to stress other than the mold opening / closing direction X, so that the movable side metal mold The die 12 can be smoothly demolded from the core surface.

Thus, in the initial stage of extrusion of the extrusion core 15, a sufficient gap is formed between the pair of extrusion core leg pieces 15a of the extrusion core 15 and the tapered opening 17a of the guide hole 17 (FIG. 4). Then, when the extruded core 15 is further extruded subsequently, the expanded portion 20b of the insert core 20 is brought into sliding contact with the tapered portion 16b of the slit 16 and spreads it. As a result, the pair of extruded core leg pieces 15a open so that their tips are separated from each other around the portion where the stress relief holes 16c are formed. Therefore, the undercut forming portion 15b is separated from each of the claw-shaped pieces 1d of the mounting claw portion 1c and released from the mold.

In FIG. 5, the ejector plate 18 is a movable side mold plate 1
3 shows a state in which the extruding core 15 is extruded until it abuts against No. 3, and in this state, the extruding core 15 is fully opened and its undercut forming portion 15b is completely removed from the undercut of the mounting claw portion 1c. . In this case, since the undercut forming portion 15b moves in a direction substantially perpendicular to the mold opening / closing direction X, no unreasonable stress is applied to the mounting claw portion 1c. Therefore, the mounting claw 1c can be easily demolded without being deformed to cause damage or dimensional failure.

After the extruding core 15 is completely removed from the mounting claw 1c in this manner, the garnish 1 is operated by a conventional means, that is, by ejecting ejector pins or air jets. Alternatively, a manipulator or the like can be used to discharge the mold apparatus 10.

Here, the slit 16 is formed of a straight portion 16a having a width equal to the thickness of the expanded portion 20b of the insert core 20 and a tapered portion 16b having a reduced width, but the straight portion 16a is omitted. Taper part 1
It can be formed only from 6b. In addition, the expansion portion 20
It is also possible to form only the straight portion 16a having a width smaller than the thickness of b. However, in these cases, since the opening of the extrusion core 15 is started simultaneously with the extrusion of the extrusion core 15,
The opening 17a of the guide hole 17 needs to be formed with a sufficiently inclined taper. Therefore, the slit 16
Is the straight portion 16a and the tapered portion 1 as in the present embodiment.
It is preferable that it is formed from 6b from the viewpoint of mold production.

It is also conceivable to fabricate the extrusion core 15 so that the pair of extrusion core leg pieces 15a are pre-biased so as to open. In this case, the expanded portion 20b of the insert core 20 is unnecessary, and the slit 16 has the straight portion 16a having the same width as the core portion 20c.
Will be formed as. However, in this case, the tip portion of the extruding core 15 is guided by the elastic force of the guide hole 1.
The opening 17a of No. 7 always comes into contact with a strong force,
As a result, the extrusion core 15 and the guide hole 17 may be damaged or worn. Therefore, it is not preferable to form the extruded core 15 in this way, and the insert core 2 having the expanding portion 20b as in this embodiment is not preferable.
It is preferable to open the extruded core 15 by 0 in terms of the reliability of its operation.

As described above, the injection molding die apparatus 10 of this embodiment is an injection molding die apparatus for molding the garnish 1 which is a resin product having the mounting claw portions 1c forming the undercut portions, and is mutually A pair of molds including a fixed mold 11 and a movable mold 12 that can be opened and closed, and an extrusion core 15 that forms a mounting claw portion 1c thereof. At the same time, the extrusion core 15 guided by the guide hole 17 of the movable mold 12 and provided to be extrudable in the mold opening / closing direction Z, and the slit 16 when the extrusion core 15 is extruded from the movable mold 12. And an insert core 20 which is a push-out core opening means for opening and pushing out the push-out core 15.

Therefore, according to the injection molding die apparatus 10 of the present embodiment, when the garnish 1 after molding is extruded,
The extrusion core 15 forming the mounting claw portion 1c is opened by the slit 16 being pushed and spread by the insert core 20, and thus is easily removed from the mounting claw portion 1c, and an excessive force is applied at this time. There is no such thing. for that reason,
Even if there are undercuts on both sides like the mounting claw 1c,
The garnish 1 after molding can be easily taken out without damaging or deforming the undercut portion.

Further, in this case, since the extruded core 15 needs to be opened by an amount corresponding to the distance from the undercut portion, that is, the height of the undercut, a wide space is not required for its operation. Therefore, it is possible to design the product shape more freely, and it is possible to appropriately set ribs or the like for reinforcement around the mounting claw portion 1c forming the undercut portion.

Further, since the extruding core is extruded in the mold opening / closing direction Z, bending stress or the like does not act on itself, and the extruding core is easily extruded and a guide hole for guiding the extruded core. Since 17 may also be formed in the mold opening / closing direction Z, it can be manufactured easily and accurately.

Further, since the extruded core 15 is formed as a single member and only the slit 16 and the portion forming the undercut portion (undercut forming portion 15b) need be processed, it is easy and labor-free. Further, it can be manufactured with high precision and accuracy. And
The injection molding die device 10 including the extrusion core 15 and the insert core 20 as the extrusion core opening means can be manufactured at low cost because of easy processing.

By the way, the injection molding die apparatus 1 of this embodiment
0 is embodied as a product for molding the garnish 1 of FIG. 8. However, the injection molding die device of the present invention having the extrusion core capable of opening legs is not limited to such a resin product, and By changing the shape of the undercut forming portion of the extrusion core and the shape of the insert core as the extrusion core opening means, it can be applied to the molding of resin products having other various undercut portions and can be embodied. it can.

For example, the injection molding die apparatus of the present invention can be applied to the molding of the garnish 1 having the mounting claw portions 1b as shown in FIGS. In this case, specifically, the undercut forming portion 15b is formed on one side of the pair of extruding core leg pieces 15a of the extruding core 15 in the above embodiment, and the tip end portion of the other extruding core leg piece 15a has its mounting claws. It is formed on a flat core surface corresponding to the portion 1b. When undercuts are provided on both sides of the mounting claw portion 1b, the undercut forming portion 15b is also formed on the other extruded core leg piece 15a. Further, the insert core 20 is formed so that the core portion 20c is omitted and only the expanding portion 20b is provided. However, the operation and effect in this case are similar to those in the above-mentioned embodiment.

Further, not only such a claw-shaped protrusion, but also a protrusion such as an insertion pin or a screw having a locking portion, a flange-shaped protrusion, a recess, an opening, or other undercut portion is used. The injection molding die apparatus of the present invention can be similarly applied to various kinds of resin products.

In these cases, the extruded core may be divided into three or more pieces, depending on the specific shape of the undercut portion. Further, as for the extrusion core leg opening means, any means may be used as long as it can spread the slit of the extrusion core and open the leg. For example, in the expanding portion 20b in the above-mentioned embodiment. It can be a wedge-shaped means consisting of only corresponding parts. Further, such an extrusion core opening means is not only fixedly arranged in the slit of the extrusion core, but also movable means operated so as to be inserted into the slit when the extrusion core is extruded. Can also be Furthermore,
Depending on the resin product to be molded, the extrusion core and the extrusion core opening means can be provided not only on the movable mold but also on the fixed mold.

[0049]

INDUSTRIAL APPLICABILITY As described above, the injection molding die apparatus of the present invention is an injection molding die apparatus for molding a resin product having an undercut portion. A pair of molds including a mold and an extrusion core that forms the undercut portion, which are split and formed elastically by a slit so that the legs can be opened, and can be extruded into the mold in the mold opening / closing direction. It is provided with an extruded core provided and an extruded core leg opening means for expanding the slit to open the extruded core when the extruded core is extruded from the mold.

Therefore, according to this injection molding die device, the undercut portion of the resin product is molded by the extrusion core, and at the time of extruding the resin product after molding, the extrusion core is opened by the extrusion core opening means. Therefore, even in the case of the undercut part where the undercut is on both sides, the extrusion core is easily released from the undercut part,
Die cut. For this reason, since an unreasonable stress is not applied to the undercut portion, the resin product after molding can be easily taken out without damaging or deforming the undercut portion.

Further, since the extruding core is formed as a single member, it can be manufactured easily, accurately and accurately, and the extruding core can be extruded in the mold opening / closing direction. Since it is provided, the means (guide hole) for guiding it can be easily and accurately processed. Therefore, there is an effect that a die device including the extrusion core can be easily and accurately manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of an injection molding die device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view corresponding to a cross section taken along the line AA of FIG. 3, showing a further enlarged main part of the movable-side mold of FIG.

FIG. 3 is a plan view showing a main part of the movable mold shown in FIG. 2 as viewed from the upper surface side.

FIG. 4 is a sectional view showing a state in an intermediate stage during extrusion of a resin product after molding.

FIG. 5 is a cross-sectional view showing a state at a final stage of extrusion of a resin product after molding.

FIG. 6 is a cross-sectional view showing a garnish which is an example of a resin product having an undercut portion.

7 is a perspective cross-sectional view of a cross section taken along line XX of FIG. 6 as viewed obliquely.

FIG. 8 is a cross-sectional view showing another garnish in which the shape of the mounting claw portion is different from that in FIGS. 6 and 7.

[Explanation of symbols]

 1 Garnish (Resin Product) 10 Injection Mold Device 11 Fixed Side Mold 12 Movable Side Mold 15 Extrusion Core 16 Slit 20 Insert Core (Extrusion Core Opening Means)

Claims (1)

[Claims] 1. An injection molding die apparatus for molding a resin product having an undercut portion, a pair of dies including a fixed-side die and a movable-side die that can be opened and closed, and opening and closing of the die. The extrusion core that is provided so as to be extrudable in any direction and is elastically divided by a slit so that the extrusion core can be opened. When the extrusion core is extruded from the mold, the slit is spread to open the extrusion core. An injection molding die apparatus comprising: an extrusion core opening means.