JP3628778B2 - Undercut mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection mold that can efficiently produce a part having an undercut portion.
[0002]
[Prior art]
Conventionally, in forming a part having an undercut part, the slide piece is moved by sliding relative to a direction different from the mold opening and closing direction by an angular pin protruding at an arbitrary angle from the fixed side mold plate, In general, only a cavity part that forms the undercut portion is released independently.
In such a conventional method, for example, in the case of molding an extremely thin cylindrical shape and a shape having a relatively large release resistance on the inner diameter side in addition to the outer diameter undercut, Usually, a part having a large mold release resistance must be processed prior to opening the mold by using another mechanism that is not linked to the operation of the molding machine such as a motor.
[0003]
This is because if the mold release process on the inner diameter side, which has a relatively large resistance without the aid of the outer periphery of the molded product, is performed, the thickness of the molded product is extremely small, and therefore an excessive load is applied at the time of mold release. This is because the molded product itself may be damaged when it acts. However, providing such a separate mechanism increases the size of the work area, and it is difficult to time the mold release process because it is not directly linked to the operation of the molding machine.
[0004]
Therefore, in order to solve the above-mentioned drawbacks, the following known techniques (Misumi plastic type standard parts catalog 1993.5-1996.4 P525-P526 described angular cam catalog No. ANC) are widespread. .
As shown in FIG. 13, the structure of the undercut mold of the above technique is an angular structure in which an axis is formed in two directions, one of which is fixed to the fixed side mold plate so as to be in the same direction as the mold opening / closing direction. One of the cavities that form two axes in the same direction as the two axes of the cam a and the angular cam a, and are formed with an angular hole b so as to be slidable with the angular cam a, and further form an undercut portion of the molded product And a slide piece c provided with a portion.
[0005]
According to the above configuration, when the mold opening is started, the angular cam a and the slide piece c start to slide with each other. At this time, since the angular cam b and the slide piece c are portions where the angular holes b are formed in the same direction as the mold opening / closing direction, the slide piece c maintains the initial position. The outer periphery of the molded product is supported. In the meantime, in order to prevent a mold release failure, a part to be released first such as an inner diameter undercut is first released. Thereafter, as shown in FIG. 14, the axial direction of the sliding portion is switched to the other direction, and the slide piece c held at the fixed position until then starts moving in the direction of releasing.
[0006]
[Problems to be solved by the invention]
However, the known technique has the following drawbacks.
In other words, when guiding the behavior of the slide piece formed with the cam groove with the angular cam, the axial direction of the angular cam is limited to two directions, ie, the mold opening direction and an arbitrary direction. In particular, it is impossible to arbitrarily set a region where the mold release speed is desired to be slowed down or a region where the speed is desired to be shortened to shorten the cycle time.
Another drawback is that the rigidity is relatively low, as in the case of a conventional general angular pin system, when the mold clamping speed is particularly high, the impact resistance causes breakage or breakage. Raised as one.
[0007]
The object of claim 1 is to realize an operation of a desired slide piece by allowing the guide speed and direction of the slide piece formed with a cam groove to be freely combined when forming a product having an undercut. It is to be possible to set a release speed corresponding to the shape. Another problem is to eliminate the presence of angular pins and angular cams that were previously fixed to the fixed side mold plate, and to improve the mold opening and closing speed without causing problems such as damage or wear of the mold. One.
[0008]
The subject of claim 2 is to further simplify the mold structure and further reduce the mold cost by controlling the drive means of the guide pin by the ejecting mechanism of the molding machine.
[0009]
[Means for Solving the Problems]
The invention of claim 1 has a pair of mold plates composed of a fixed side and a movable side forming a cavity therebetween, and slides in a direction different from the mold opening / closing direction and forms an undercut portion of the molded product. In an undercut die having at least one slide piece fixed to a part of the inner wall surface of the cavity, the die has a plurality of directions from a movable side sliding surface of the slide piece to a fixed side plane which is an opposite surface thereof. a cam groove which penetrates, comprising the induction pin that slidably fitted match to the cam groove, an inductive pin driving means for rotatably driving the induction pins to the mold opening and closing direction, the induction pins, the The undercut die is provided on the movable side separately from the slide piece .
[0010]
In the invention of claim 1, when the mold opening is started, the movable side mold plate and the fixed side mold plate are first separated, and the molded product is released only from the cavity formed in the fixed side mold plate. At the same time, the guide pin driving means starts to operate in the mold opening / closing direction, and the guide pin separate from the slide piece, which was initially located closest to the fixed side in the slide piece cam groove, is the cam groove. Start moving in the mold opening direction while sliding against each other. At this time, there is a part with particularly large release resistance other than the outer diameter undercut, and when it is desired to release this part first, the cam groove of the slide piece is formed in the same direction as the mold opening direction in the initial area. By doing so, the slide piece can be held at the initial position when the mold is clamped even if the guide pin is operating.
[0011]
If the slide piece is at a level that can be kept relatively low without stopping, the cam groove angle is made gentle relative to the mold opening direction, and further in the region where the mold release is completed. What is necessary is just to give the angle of a cam groove.
As described above, since the guide pin moves in the mold opening / closing direction, the cam groove is formed with a plurality of directions, so the behavior of the slide piece corresponds to the cam groove shape. Therefore, the behavior of the slide piece is changed by adjusting the cam groove shape, and the processing of the undercut portion is performed at a desired timing or speed.
[0012]
A second aspect of the present invention is the undercut die according to the first aspect, wherein the guide pin driving means is controlled by an ejection mechanism of an injection molding machine.
[0013]
In the invention of claim 2, the guide pin driving means is controlled by the ejection mechanism of the injection molding machine, and the movement of the guide pin in the mold opening direction is performed by pulling back the ejection mechanism that was initially projected. Others are the same as in the first aspect.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
1 to 7 show the present embodiment, FIG. 1 is a schematic configuration diagram, FIG. 2 is a sectional view of a slide piece, FIG. 3 is a side view thereof, FIG. 4 is a perspective view of a guide pin, and FIGS. It is sectional drawing which shows the behavior at the time of mold opening.
The mold according to the present embodiment has a thin and cylindrical shape, a strip-like undercut on the outer periphery, and a cavity 14 that can have an orientation taper of 0 ° on the inner diameter side.
[0015]
A fixed-side mold plate 1 and a movable-side mold plate 2 that form a cavity 14 are disposed. A stripper plate 7 is provided on the movable side back surface of the movable side mold plate 2 so that the stripper plate 7 and the movable side mold plate 2 can be brought into close contact with each other with a load smaller than the molding machine platen driving load. A parting lock 12 is fixedly attached to the side end. Reference numeral 4 denotes a movable side mounting plate, which is fastened to the stripper plate 7 with the spacer 5 interposed therebetween, and is fixed to the movable side platen 101.
[0016]
Reference numeral 15 denotes an eject plate, which is fastened so as to be interlocked with the molding machine ejector rod 102, and holds the opposite end portion of the core 14a that forms the inner diameter side of the cavity 14 at the center. Further, the core 14 a penetrates the stripper plate 7 and the movable side mold plate 2 to form a cavity 14 by the end portion on the cavity side.
The parting lock 12 is a catalog No. made by MISUMI Corporation. This is a diversion of PLM components.
[0017]
The fixed-side template 1 is fastened to the fixed-side mounting plate 3, and the fixed-side mounting plate 3 is positioned at the injection position by the locate ring 17 and is fixed to the fixed-side platen 100. Further, a tension link 6 is provided between the fixed side mold plate 1 and the movable side mold plate 2 so as to lock both mold plates when a desired mold opening amount L is reached.
The tension link 6 is a rectangular shape in which one bolt is screwed to each of the fixed side mold plate 1 and the movable side mold plate 2 and the length thereof is adjusted so that both bolts can be locked with a desired mold opening amount L. The catalog No. made by MISUMI Corporation. This is a diversion of TLK components.
[0018]
Next, the structure around the undercut processing mechanism will be described.
Slide pieces 18 are attached to the cavity side surface of the movable side mold plate 2 so as to be slidable in the direction perpendicular to the mold opening direction, and are attached at two positions on opposite sides of the cavity 14. As shown in FIGS. 2 and 3, the slide piece 18 has a taper 18 c formed on one surface of the block, and an undercut portion serving as a part of the cavity 14 is provided on the surface facing the surface. . Further, a backup 8 is fixed to the fixed-side template 1 so that the slide piece 18 can surely form the cavity 14 and clamp the resin pressure of the molded product 22 when the mold is clamped.
[0019]
The backup 8 has a taper 8a which is the same as the angle of the taper portion 18c of the slide piece 18, and both the taper portions 18c and 8a of the slide piece 18 and the backup 8 are just before mold clamping (0.01 to 0.02 mm). Are assembled so that a force acts on the slide piece 18 in a direction perpendicular to the mold opening direction (direction in which the cavity 14 is to be formed). Reference numeral 19 denotes a guide pin. As shown in FIG. 4, a cylindrical projection 19 a is projected from two long axis surfaces at one end of a rectangular parallelepiped block. The stripper plate 7 grips one end of the guide pin 19 that slidably penetrates the movable side mold plate 2 and is opposite to the projection 19a formation side. Similarly to the slide piece 18 and the backup 8, the guide pins 19 are provided symmetrically at two positions with the cavity 14 interposed therebetween.
[0020]
Reference numeral 20 denotes a cam groove for slidably fitting the protrusion 19 a of the guide pin 19, and the cam groove 20 is provided symmetrically at two locations with the cavity 14 in between. Each cam groove 20 is formed in the same direction as the mold opening direction by a depth H from the fixed side surface 18a of the slide piece 18 (hereinafter, cam groove parallel portion 20a), and the movable side slide of the slide piece 18 from the depth H is formed. The moving surface 18b is formed so as to be inclined toward the cavity 14 (hereinafter, cam groove inclined portion 20b). That is, the cam groove inclined portion 20b of the cam groove 20 is formed to extend in the 5 o'clock direction and the 7 o'clock direction, respectively, when the direction of the fixed side surface 18a of the cam groove parallel portion 20 is 12 o'clock. .
[0021]
Further, the cross-sectional shape perpendicular to the mold opening / closing direction of the cam groove 20, that is, the cross-sectional shape corresponding to the layout of FIG. 3 is the projection surface shape of the projection 19 a of the guide pin 19, ie, It has the same shape as the projection surface in the direction of the arrow, and the protrusion 19a is slidable without play. In addition, an escape groove 21 is provided at the center position of the cam groove 20 so as to avoid at least the behavior range of the shaft portion 19b of the guide pin 19.
[0022]
A series of behaviors when the mold having the above-described structure is opened will be described with reference to FIGS.
FIG. 5 shows the clamped state.
The protrusion 19 a of the guide pin 19 is positioned closest to the fixed side of the cam groove parallel portion 20 a formed on the slide piece 18, whereby the slide piece 18 is held at the position where the cavity 14 is formed. In this state, the clamping force on the mating surface of the taper portion 8a of the backup 8 and the taper portion 18b of the slide piece 18 is converted from the mold opening / closing direction to the direction in which the slide piece 18 suppresses the resin pressure, and the cavity 14 is It is in a state where the shape can be reliably maintained.
[0023]
FIG. 6 shows a state in which the mold is further opened by H after the mold opening is started and the parting lock 12 is released.
When mold opening is started, first, the movable side mold plate 2 and the fixed side mold plate 1 are detached, and the molded product 22 is released only from the fixed side mold plate 1. At this time, the movable side mold plate 2 and the stripper plate 7 disposed on the back side of the movable side are simultaneously operated in close contact with each other by the action of the parting lock 12. This behavior is realized by the fact that the adhesion force of the parting lock 12 is smaller than the molding machine platen driving load and larger than the resistance when the mold is opened (sprung release resistance, tensile link friction resistance, etc.). is there.
[0024]
Thereafter, when the mold opening amount L is reached, the tension link 6 locks the fixed-side mold plate 1 and the movable-side mold plate 2, and the fixed-side mold plate 1 and the stripper plate 7 are brought into close contact with each other by the driving load on the molding machine platen. The parting lock 12 that has been released is released. Thereafter, the stripper plate 7 starts to detach from the movable side mold plate 2 in the mold opening direction, and the guide pins 19 fixed to the stripper plate 7 are cams formed on the slide piece 18 through the movable side mold plate 2. Sliding with the cam groove parallel portion 20a of the groove 20 starts.
[0025]
In this state, since the protrusion 19a of the guide pin 19 still exists within the cam groove parallel portion 20a, the slide piece 18 is held at the initial position without breaking the shape of the cavity 14. During this time, the eject plate 15 starts to operate, and the core 14a is pulled out while being assisted by the slide piece 18 so as not to break the shape of the molded product 22.
[0026]
FIG. 7 shows a state where the mold opening is completed.
When the projection 19a of the guide pin 19 reaches the region of the cam groove inclined portion 20b, the slide piece 18 starts to operate in the mold release direction. After all the molds are opened, the molded product 22 is taken out of the mold.
[0027]
According to the present embodiment, when forming a part having an undercut, the cam groove in the slide piece is formed in an appropriate shape, and the guide speed and direction of the slide piece can be freely combined. Operation of the desired slide piece was realized. In addition, since there is no angular pin or angular cam that has been conventionally fixed to the fixed-side mold plate, there is no inconvenience such as breakage or wear of the mold, and the mold opening / closing speed can be improved. . Therefore, it can contribute to a dramatic improvement in production efficiency.
[0028]
(Embodiment 2)
8 and 9 show the present embodiment, FIG. 8 is a schematic configuration diagram, and FIG. 9 is a sectional view in a state where the mold opening is completed.
The present embodiment is different from the first embodiment in that the stripper plate, the lock mechanism, and the tension link are eliminated, and the other components are composed of the same components, and the same components are denoted by the same reference numerals. The description is omitted.
[0029]
In the present embodiment, the movable side mold plate 2 is fastened to the movable side mounting plate 4 directly via the spacer 5. Further, there is no restriction on the amount of mold opening between the fixed side mold plate 1 and the movable side mold plate 2 by the tension link 6 as in the first embodiment. Further, the guide pin 19 and the core 14a are directly gripped so as to be interlocked with the eject plate 15.
[0030]
After the mold opening is started, the mold having the above configuration starts to move in the direction in which the eject plate 15 is pulled back, and the core 14a starts to be pulled out from the molded product 22. Then, when the eject plate 15 moves in the same direction by H, the projection 19a of the guide pin 19 starts sliding with the cam groove inclined portion 20b, and the slide piece 18 is guided in the mold release direction.
[0031]
According to the present embodiment, the projecting mechanism of the molding machine is diverted to the guide pin driving means, so that the structure can be made simpler than the mold shown in the first embodiment, and the cost can be reduced. However, it is possible to provide a mold having the same function as in the first embodiment.
[0032]
(Embodiment 3)
10 to 12 show this embodiment, FIG. 10 is a partial cross-sectional view showing the structure around the undercut processing mechanism, FIG. 11 is a partial cross-sectional view immediately after opening the same mold, and FIG. It is a fragmentary sectional view.
In the present embodiment, only portions different from those of the second embodiment will be described.
[0033]
The core 52a has an extraction taper 52b formed of 1 ° to 2 ° at a portion where the cavity 52 is formed. Therefore, the inner diameter side of the molded product 53 has a shape obtained by transferring the extraction taper 52b.
[0034]
In addition, each of the cam grooves 51 formed in the two slide pieces 50 provided symmetrically with the cavity 52 interposed therebetween is inclined toward the cavity 52 with a gentle slope by a depth H from the fixed-side surface 50a of the slide piece 50. Formed (hereinafter referred to as cam groove first inclined portion 51a), and formed from the depth H to the movable side sliding surface 50b of the slide piece 50 with a strong inclination toward the cavity 52 (hereinafter referred to as cam groove second inclined portion 51b). ing. That is, when the mold opening / closing direction fixed side is set to 12:00, the cam groove first inclined portion 51a is formed to extend in the direction of 5:50 and 6:10, and the cam groove second inclined portion 51b is 4 It is formed to extend in the direction of 30:30 and 7:30.
[0035]
After the mold opening is started, the mold having the above configuration starts to move in the direction in which the core 52a is pulled back, and the molded product 53 starts to be released from the core 52a. At the same time, the slide piece 50 starts to be detached from the molded product 53. Since the moving speed of the slide piece 50 at this time corresponds to the cam groove first inclined portion 51a, the moving speed becomes a relatively slow speed and suppresses deformation or cracking of the molded product at the time of mold release. In addition, since the resistance when the molded product 53 is released from the core 52a is relatively small due to the extraction taper 52b provided in the core 52a, the molding is performed by the release behavior of the core 52a even if the molded product 53 is not supported. The product 53 is not deformed or cracked.
[0036]
Then, as shown in FIG. 12, when the eject plate 15 moves in the same direction by H, the projection 19a of the guide pin 19 starts sliding with the cam groove second inclined portion 51b, and is relatively faster than before. The slide piece 50 moves in the release direction.
[0037]
According to the present embodiment, since the cam groove shape is formed so that the slide piece moves slowly at the time of mold release and then moves quickly thereafter, the molded product is not deformed or cracked. In addition, the undercut process and take-out of the molded product can be performed without any special delay in time compared with a normal undercut process mold.
[0038]
【The invention's effect】
The effect of claim 1 is that when molding a part having an undercut, a guide pin separate from the slide piece is arranged on the movable side, and the guide speed and direction of the slide piece can be freely combined. Thus, a desired slide piece operation can be realized. Also, since there is no angular pin that has been fixed to the fixed side mold plate in the past, the mold opening and closing speed can be improved without causing problems such as damage to the molded product, damage to the mold, or wear. it can.
[0039]
According to the second aspect of the present invention, a simple mold structure can be obtained by diverting the ejecting mechanism of the molding machine to the guide pin driving means, and the mold having the same function as that of the first aspect can be achieved at low cost. Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment.
FIG. 2 is a cross-sectional view showing the first embodiment.
FIG. 3 is a side view showing the first embodiment.
4 is a perspective view showing Embodiment 1. FIG.
FIG. 5 is a cross-sectional view showing the first embodiment.
FIG. 6 is a cross-sectional view showing the first embodiment.
FIG. 7 is a cross-sectional view showing the first embodiment.
FIG. 8 is a schematic configuration diagram showing a second embodiment.
FIG. 9 is a cross-sectional view showing a second embodiment.
FIG. 10 is a partial cross-sectional view showing a third embodiment.
FIG. 11 is a partial cross-sectional view showing a third embodiment.
12 is a partial sectional view showing Embodiment 3. FIG.
FIG. 13 is a partial cross-sectional view showing a conventional form.
FIG. 14 is a partial cross-sectional view showing a conventional form.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed side mold plate 2 Movable side mold plate 3 Fixed side mounting plate 4 Movable side mounting plate 5 Spacer 6 Pull link 7 Stripper plate 8 Backup 12 Parting lock 14 Cavity 14a Core 15 Eject plate 17 Locating ring 18 Slide piece 19 Guide pin 19 20 Cam groove 22 Molded product 100 Fixed side platen 101 Movable side platen 102 Molding machine ejector rod

Claims (2)

A part of the inner wall surface of the cavity that has a pair of mold plates composed of a fixed side and a movable side that form a cavity therebetween, slides in a direction different from the mold opening and closing direction, and forms an undercut portion of the molded product. In an undercut mold having at least one slide piece fixed,
A cam groove penetrating in a plurality of directions from the movable side sliding surface of the slide piece to the fixed side plane which is the opposite surface;
And induction pins that match slidably fitted into the cam groove,
A guide pin driving means for freely driving the guide pin in the mold opening and closing direction ;
The undercut die , wherein the guide pin is disposed on the movable side separately from the slide piece . 2. The undercut die according to claim 1, wherein the guide pin driving means is controlled by an ejection mechanism of an injection molding machine.

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