JP4659050B2 - Mold for resin molding - Google Patents

Description

  The present invention relates to a resin molding die, and particularly to a resin molding die provided with an ejector pin.

  Conventionally, as a resin molding die provided with an ejector pin, a synthetic resin molding die in which a molded product is extruded using a knockout pin that is an ejector pin, a through-hole for fitting the knockout pin is used. There is a molding die for synthetic resin characterized in that an inner wall is formed of a thermosetting resin (see Patent Document 1).

In particular, in the molding die, as shown in FIG. 2 of Patent Document 1, a molding die in which a separate sleeve 14 formed of a thermosetting resin is incorporated in the through hole 8 of the movable die 6. Is disclosed.
JP-A-52-78960

  However, in the above-described molding die, it is necessary to separately form the sleeve 14 with a thermosetting resin, but it is not easy to process the thermosetting resin material with higher dimensional accuracy than the metal material, and the sleeve It is difficult to form an optimal gap between the ejector pin and the ejector pin. For this reason, when the gap is too large, if a molten thermosetting resin having high fluidity is injected and filled, the resin leaks and a resin burr is likely to occur. Moreover, when the said clearance gap is too small, there exists a problem that the slidability of an ejector pin falls.

  In view of the above problems, an object of the present invention is to provide a mold for resin molding that is easy to process, ensures slidability of ejector pins, and does not generate resin burrs.

In order to solve the above problems, a mold for resin molding according to the present invention includes a mold body that forms at least a part of a cavity for injecting and filling a molten thermosetting resin, and the mold body. A resin molding die that is slidably inserted into a through-hole communicating with the cavity and that pushes out a molded product molded into the cavity, and is formed in the through-hole of the die body. The sliding portion of the ejector pin that slides is a disc-shaped first guide portion, and an inclined portion that is continuous with the first guide portion and has a truncated cone shape that decreases in outer diameter as the distance from the cavity increases. the gap between the second guide portion of cylindrical continuous to the inclined portion consists, inner peripheral surface and the outer circumferential surface of the inclined portion of the frustoconical provided on the ejector pin of the through hole, the cavity Injected heat In-resistant resin, with the thickness to form a not thick seal portion with distance from the end portion of the cavity side, finer than the surface roughness of the inner peripheral surface of the through hole a surface roughness of the outer peripheral surface of the ejector pin By doing so, the seal portion is held on the inner peripheral surface of the through hole.

  According to the present invention, instead of forming a separate seal portion with a thermosetting resin, it is injected into the cavity in the gap between the inner peripheral surface of the through hole of the mold body and the outer peripheral surface of the ejector pin. A thermosetting resin is intruded to form a seal portion. For this reason, it is not necessary to manufacture a special part with a thermosetting resin, and a seal part can be formed easily and a seal part with high dimensional accuracy can be formed. Generation of resin burrs due to leakage can be prevented.

  Further, according to the present invention, the seal portion does not fall into the cavity from the through hole.

  Furthermore, according to the present invention, even if the seal portion is formed in the gap between the inner peripheral surface of the through hole and the outer peripheral surface of the ejector pin, the seal portion is separated from the outer peripheral surface of the ejector pin due to the difference in sliding resistance. It peels off and continues to be held on the inner peripheral surface of the through hole.

According to the present invention , the seal portion can be formed by the truncated cone-shaped inclined portion, while the first and second guide portions support the ejector pin at two points, so that the sliding characteristics are stable.

As a different embodiment according to the present invention, the inclination angle of the inclined portion of the ejector pin is preferably 1 to 30 degrees, particularly 1 to 5 degrees.
According to the present embodiment, the molten thermosetting resin smoothly enters the gap formed between the inner peripheral surface of the through hole and the outer peripheral surface of the ejector pin to form a seal portion, and the ejector pin Smooth sliding characteristics can be secured.

As a new embodiment according to the present invention, the inclined portion of the ejector pin is connected to the first inclined portion and the first inclined portion, and the second inclined portion has a larger inclination angle than the first inclined portion. The structure which consists of may be sufficient.
According to this embodiment, since the inclination angle of the second inclined portion is large, the seal portion is shortened, while the second guide portion can be relatively enlarged, and the sliding characteristics of the ejector pin are further stabilized.

As another embodiment according to the present invention, a seal portion formed of a thermosetting resin injected into the cavity is provided in an annular groove provided along the inner peripheral surface of the through hole of the mold body. It may be left.
According to this embodiment, since the thermosetting resin that has entered the annular groove from the cavity forms the seal portion, it is possible to easily form the seal portion that does not easily fall off, and to generate resin burrs while ensuring sliding characteristics. There is an effect that a mold for resin molding capable of preventing the above is obtained.

An embodiment according to the present invention will be described with reference to the accompanying drawings of FIGS.
1st Embodiment is a case where it applies to the metal mold | die for resin sealing mounted in a resin sealing apparatus, as shown in FIG. 1 thru | or FIG.

  The resin sealing device includes a lower fixed platen 11 fixed to a base 10, an upper fixed planten 13 fixed to upper end portions of four tie bars 12 erected at corners of the lower fixed platen 11, The movable platen 14 is assembled between the lower and upper fixed platens 11 and 13 through the tie bar 12 so as to be movable up and down.

  An upper mold base 20 (FIG. 2) is fixed to the lower surface of the upper fixed platen 13. The upper chess 21 has space blocks 23 fixed to both side edges of the upper surface of the upper holder base 22 and a large number of support pillars 24 protruding at a predetermined pitch on the entire upper surface. Further, the ejector plate 25 is disposed by fitting a through hole of the ejector plate 25 into the support pillar 24. The support pillar 24 and the space block 23 receive a load applied to the upper holder base 22.

  On the other hand, the movable platen 14 is supported so as to move up and down via a toggle mechanism 15. The toggle mechanism 15 rotates a ball screw 18 via a timing belt 17 in which a servo motor 16 rotates, thereby expanding and contracting a crank 19 to move the movable platen 14 up and down. Further, on the upper surface of the movable platen 14, a lower mold base 26 (FIG. 2) having a lower mold chess 30 slidably fitted on the upper surface is mounted.

  As shown in FIGS. 2 and 3, the lower chess 30 has a pot block 33 in which a plurality of pots 32 are provided at a predetermined pitch at the center of the upper surface of the lower holder base 31. Further, on both sides of the pot block 33, cavity blocks 35 in which cavities 34 are formed at a predetermined pitch are arranged in parallel. Further, the lower holder base 31 has a space block 36 fixed to both side edges of the lower surface, and a large number of support pillars 37 protruding at a predetermined pitch on the entire remaining lower surface. Then, after a pin plate 41 having a plurality of ejector pins 50 protruding and stacked is integrated on the upper surface of the ejector plate 40, the insertion holes 46 penetrating the ejector plate 40 and the pin plate 41 are inserted into the support pillars 37. And is disposed on the lower surface of the lower holder base 31. Further, the ejector plate 40 and the pin plate 4 can be moved up and down relative to the lower holder base 31 by screwing the bolts 44 to the lower surface of the lower holder base 31 via the cylindrical collar 42 and the washer 43. Prevent it from coming off. At this time, the vertical movement of the ejector plate 40 and the pin plate 41 is guided by the cylindrical collar 42. With this configuration, the support pillar 37 and the space block 36 receive a load applied to the lower holder base 31. Further, the pin plate 41 and the ejector plate 40 are urged downward through a plurality of coil springs 45 disposed between the lower holder base 31 and the pin plate 41.

  As shown in FIGS. 4 and 5, the cavity block 35 has an ejector pin 50 slidably inserted in a through hole 38 communicating with the cavity 34. The sliding portion 51 provided at the upper end of the ejector pin 50 includes a first guide portion 52 having a disc-shaped tip edge portion, a truncated cone-shaped inclined portion 53 continuous to the first guide portion 52, and The second guide portion 54 is adjacent to the inclined portion 53.

In particular, the inclination angle of the inclined portion 53 is 1 to 30 degrees, preferably 1 to 5 degrees. This is because if the inclination angle is less than 1 degree, the annular seal portion 60 is difficult to peel from the inclination portion 53. In addition, when the inclination angle exceeds 30 degrees, the length dimension L1 of the annular seal portion 60 is shortened and the area in contact with the through hole 38 is reduced, so that the adhesion force of the annular seal portion 60 to the through hole 38 is reduced. It is because it is too much.
Further, the surface roughness of the sliding portion 51 is equal to the surface roughness of the through-hole 38 or finer than the surface roughness of the inner peripheral surface of the through-hole 38. For example, when the surface roughness Ra (centerline average roughness) of the sliding portion 51 is 0.8 μm and the surface roughness Ra of the through hole 38 is larger than 0.8 μm, the surface roughness is increased. Due to this difference, the adhesion force between the annular seal portion 60 and the through hole 38 can be made larger than the adhesion force between the annular seal portion 60 and the inclined portion 53. Further, even when the surface roughness Ra of the through hole 38 is 0.8 μm, the amount of contact between the annular seal portion 60 and the through hole 38 is reduced by the amount of the inclined portion 53 formed. It can be made larger than the adhesion force between 60 and the inclined portion 53.

  According to this embodiment, the annular seal portion 60 having the length L1 is formed in the through hole 38, and high sealing performance can be ensured. Further, since the two-point support structure is provided by providing the first and second guide portions 52 and 54, there is an advantage that the sliding characteristic of the ejector pin 50 is stabilized.

  In the present embodiment, the case where the outer peripheral surface of the inclined portion 53 of the ejector pin 50 has a truncated cone shape has been described. However, the present invention is not limited to this, and the ejector pin 50 has a cylindrical shape and the inner periphery of the through hole 38. The surface may be frustoconical. The outer peripheral surface of the ejector pin 50 and the inner peripheral surface of the through hole 38 may be frustoconical. Furthermore, although the case where the present invention is applied to the lower mold chess 30 has been described in the present embodiment, it is needless to say that the present invention may be applied to the case where an ejector pin is provided on the upper mold chess 21.

Next, the resin sealing process will be described.
First, by driving the toggle mechanism 15, the movable platen 14 is raised to join the upper surface of the lower die chess 30 to the lower surface of the upper die chess 21, and a lead frame (not shown) is sandwiched. Then, by pushing up the cylinder block 27 shown in FIG. 2, the tablet-shaped thermosetting resin (not shown) in the pot 32 is heated and pressed, and the molten thermosetting resin is injected into the cavity 34 and solidified. When molten thermosetting resin is injected into the cavity 34, the molten thermosetting resin enters and solidifies into the gap between the inner peripheral surface of the through hole 38 of the cavity block 35 and the outer peripheral surface of the ejector pin 50. As a result, a wedge-shaped annular seal portion 60 is formed. The ejector pin 50 erected on the pin plate 41 is driven by driving the toggle mechanism 15 in the reverse direction and pushing up the ejector plate 40 with the ejector rod 28 while lowering the lower die chess 30 (FIG. 2). The molded product is ejected from the cavity 34. At this time, due to the difference in sliding resistance, the annular seal portion 60 peels off from the outer peripheral surface of the ejector pin 50 and remains in the through hole 38, and thereafter functions as the annular seal portion 60. In particular, even if a part of the annular seal portion 60 is missing, a new thermosetting resin is replenished during the molding process, so that the sealing performance does not deteriorate.
In addition, the said seal part does not need to be a perfect annular | circular shape, and a discontinuous cross-sectional substantially C shape may be sufficient.

As shown in FIGS. 6 and 7, the second embodiment is the same as the first embodiment except that the shape of the sliding portion 51 of the ejector pin 50 is different. The same numbers are assigned and explanations are omitted.
The sliding portion 51 of the ejector pin 50 according to the present embodiment includes a first guide portion 52 provided at a tip edge portion, a first inclined portion 55 continuous with the first guide portion 52, and the first inclined portion 55. And a second inclined portion 56 having a large inclination angle, a narrow neck portion 57 continuing to the second inclined portion 56, and a second guide portion 54 adjacent to the narrow neck portion 57. Note that the inclination angle of the first inclined portion 55 is substantially the same as in the first embodiment described above.
According to this embodiment, the 1st inclination part 55 is short, and the cyclic | annular seal part 60 becomes the length dimension L2, and is short. For this reason, the 2nd guide part 54 can be formed long and there exists an advantage that a sliding characteristic improves further.

In the third embodiment, as shown in FIGS. 8 and 9, an annular notch groove 39 is formed in the vicinity of the opening edge of the inner peripheral surface of the through hole 38, and the heat that has entered the notch groove 39 at the time of molding is formed. This is a case where the annular seal portion 60 is formed of a curable resin.
According to this embodiment, the through hole 38 of the cavity block 35 is processed into a cylindrical shape, and the annular notch groove 39 is formed in the vicinity of the opening edge of the through hole 38, while the ejector pin 50 is formed into a cylindrical shape. All you need to do is process it. For this reason, there exists an advantage that the shape of the ejector pin 50 becomes simple and processing becomes easy.
In addition, after separately producing a part having the notch groove 39, the part may be incorporated into a step provided on the bottom surface of the cavity block 34.

In addition, by combining Embodiment 3 with Embodiment 1 or Embodiment 2 described above, a resin molding die having a seal portion that has higher sealing performance and is less likely to drop off is obtained.
Further, if a vertical escape groove is formed in the second guide portion of the first and second embodiments, even if the seal portion is missing, it can be discharged to the outside through the escape groove. There is an advantage that it does not adversely affect.

  The resin molding die according to the present invention is not limited to the case where it is applied to the above-described resin sealing device, but can be applied to other thermosetting resin molding die.

It is a schematic front view which shows the resin sealing apparatus which mounts the metal mold for resin molding which concerns on 1st Embodiment of this invention. It is a principal part disassembled perspective view of the resin sealing apparatus shown in FIG. It is sectional drawing of the metal mold | die for resin molding shown in FIG. It is an expanded sectional view before operation | movement of the A section shown in FIG. It is an expanded sectional view after the operation | movement of the A section shown in FIG. It is an expanded sectional view before operation which shows a 2nd embodiment concerning the present invention. It is an expanded sectional view after operation showing a 2nd embodiment concerning the present invention. It is an expanded sectional view before operation which shows a 3rd embodiment concerning the present invention. It is an expanded sectional view after operation showing a 3rd embodiment concerning the present invention.

20: Upper mold base 21: Upper mold chess 22: Upper holder base 24: Support pillar 26: Lower mold base 30: Lower mold chess 31: Lower holder base 32: Pot 33: Pot block 34: Cavity 35: Cavity block 40: Ejector plate 41: Pin plate 42: Cylindrical collar 43: Washer 44: Bolt 45: Coil spring 50: Ejector pin 51: Sliding part 52: First guide part 53: Inclined part 54: Second guide part 55: First 1 inclined portion 56: second inclined portion 57: narrow neck portion 60: annular seal portion

Claims (3)

A mold body that forms at least a portion of a cavity for injecting and filling molten thermosetting resin;
A mold for resin molding comprising: an ejector pin which is slidably inserted into a through hole communicating with the cavity of the mold body and pushes out a molded product molded in the cavity;
The ejector pin sliding portion that slides in the through hole of the mold body is continuous with the disc-shaped first guide portion and the first guide portion, and the outer diameter decreases as the distance from the cavity increases. An inclined portion that is a truncated cone shape, and a cylindrical second guide portion that is continuous with the inclined portion,
The gap between the inner peripheral surface and the outer circumferential surface of the inclined portion of the frustoconical provided on the ejector pin of the through hole, a thermosetting resin injected into the cavity, wall thickness from the end portions of the cavity side to form a not thick seal portion increasing distance, by the surface roughness of the outer peripheral surface of the ejector pin finer than the surface roughness of the inner peripheral surface of the through hole, the inner periphery of the through hole of the seal portion A mold for resin molding characterized by being held on a surface. The mold for resin molding according to claim 1 , wherein an inclination angle of the inclined portion of the ejector pin is 1 to 30 degrees. The inclined portion of the ejector pin, and the first inclined portion, continuous with the first inclined portion, and, according to claim 1, characterized in that it consists of a second inclined portion having a large inclination angle than said first inclined portion Or the metal mold for resin molding of 2 .

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