JP2008105329A - Lock pin bushing, runner lock pin and injection molding mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding mold which allows a reduction of the frequency of occurrence of resin flash and independent adjustment of the depth and the length of the vent. <P>SOLUTION: A runner lock pin 21 is inserted through a pin hole of a lock pin bushing 18 formed in a runner stripper plate 9, and a gas discharge passage 30 is formed between the pin hole and the lock pin 21. Two or more gas discharge grooves 31 discharging the gas in the runner 16 are formed in the inner peripheral surface of the pin hole, and one end of each gas discharge groove 31 is opened into the runner 16 while the other end communicates with the gas discharge passage 30. The outer peripheral surface of a flange portion 24 arranged on the lock pin 21, the gas discharge groove 31 constitute a narrow passage 33 having a cross-section of the passage smaller than that of the gas discharge passage 30, and the narrow passage 33 is opened directly into the runner 16. The depth of the gas discharge groove 31 is made the same as the depth of the bent, and the thickness of the flange 24 as the length of the bent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injection mold used for resin molding, and a lock pin bush and a runner lock pin provided in the injection mold.

  2. Description of the Related Art Conventionally, in an injection mold used for molding electronic parts and the like, resin molded bodies such as LED packages have recently been remarkably downsized and thinned, and the resin portion has been made thinner. In order to fill the resin part that has been made thinner without stress, there are many air vents that efficiently exhaust the exhaust gas (outgas) generated during resin injection from the cavity, and exhaust gas from the runner. Has been done.

  Conventionally, as shown in FIG. 9, there is an injection mold in which an air vent structure is provided at a portion of a runner lock pin 62 that is a terminal of resin flow in order to discharge exhaust gas in the runner 61 (see Patent Document 1 below). .

  According to this, a bush insertion hole 79 is formed in the runner plate 63, and a cylindrical lock pin bush 64 is provided in the bush insertion hole 79. The lock pin bush 64 is formed with pin holes 65 penetrating both end faces. A runner lock pin 62 that holds the resin in the runner 61 is inserted into the pin hole 65. A holder 66 projects from the end of the runner lock pin 62 facing the runner 61.

  As shown in FIG. 10, a lock pin notch 67 is formed on the end surface and the outer peripheral surface of the runner lock pin 62 facing the runner 61. The lock pin notch 67 includes a wide enlarged opening 68 formed on the end surface facing the runner 61, a narrow narrow part 69 continuous with the wide open part 68, an exhaust groove 70 continuous with the narrow part 69, and an exhaust groove. The outer opening 71 is continuous with the outer wall 70. The narrow portion 69 is formed narrower than the enlarged opening 68 and the exhaust groove 70.

  As shown in FIG. 11, a bush notch 73 is formed on the end surface and the outer peripheral surface of the lock pin bush 64 facing the runner 61. The bush notch 73 includes a wide enlarged opening 74 formed on the end face facing the runner 61, a narrow narrow part 75 continuous with the wide open part 74, an exhaust groove 76 continuous with the narrow part 75, and an exhaust groove 76. The outer opening 77 is continuous with the outer opening 77. The narrow portion 75 is formed narrower than the enlarged opening 74 and the exhaust groove 76.

Each of the enlarged openings 68 and 74 is composed of an inclined surface that inclines inward in the radial direction and expands in the circumferential direction closer to the runner 61.
When the filled resin travels in the runner 61, the exhaust gas in the runner 61 (gas generated from air or filled resin) is generated by the lock pin notch 67 and the lock pin bush 64 between the runner lock pin 62 and the lock pin bush 64. It flows through the bush notch 73 between the runner plate 63 and discharged to the outside of the injection mold.

In addition, according to the thinning of the resin part, the resin molding part of electronic parts such as connectors and optical semiconductor packages has PC (polycarbonate), POM (polyacetal), PPA (polyphthalamide), LCP (liquid crystal polymer), etc. A resin with high fluidity is used.
JP-A-2005-324529

  However, in the above-described conventional type, as shown in FIG. 10, the enlarged opening 68 of the lock pin notch 67 is inclined inward in the radial direction and enlarged in the circumferential direction as the side closer to the runner 61. The opening sectional area of 68 is larger than the channel sectional area of the narrowed portion 69. Therefore, when the resin with high fluidity is filled in the runner 61, a part of the resin is likely to enter the enlarged opening 68 of the lock pin notch 67, and therefore the frequency of occurrence of resin burrs increases. There's a problem. Such resin burrs may fall off when the resin in the runner 61 is collected, and production efficiency may be significantly reduced.

  Further, the exhaust performance as described above is determined by the vent depth A and the vent length B (bent land) of each narrow portion 69, 75 as shown in FIG. Here, the vent depth A of the lock pin notch 67 is a radial interval between the outer peripheral surface of the runner lock pin 62 and the inner peripheral surface of the lock pin bush 64 in the narrow portion 69, and The vent length B is the length of the narrow portion 69 in the lock pin axial direction 62a. The vent depth A of the bush notch 73 is a radial distance between the outer peripheral surface of the lock pin bush 64 and the inner peripheral surface of the bush insertion hole 79 in the narrow portion 75, and the vent length of the bush notch 73. B is the length of the narrow portion 75 in the lock pin axial direction 62a.

  The deeper the vent depth A or the shorter the vent length B, the lower the exhaust resistance and the smoother the exhaust. However, when the vent depth A becomes too deep or the vent length B becomes too short, the resin easily enters the narrow portions 69 and 75, and there is a concern about the occurrence of resin burrs. Further, when the vent depth A becomes too shallow or when the vent length B becomes too long, the narrow portions 69 and 75 are likely to be clogged.

  For this reason, it is necessary to individually adjust the vent depth A and the vent length B of the narrow portions 69 and 75 to optimum values. However, when the runner lock pin 62 is processed and the vent depth A of the lock pin notch 67 is adjusted, the value of the vent length B also changes as the value of the vent depth A changes. There is a problem that it is difficult to adjust only the vent depth A alone. For the same reason, there is a problem that it is difficult to adjust only the vent length B alone.

  Further, when the lock pin bush 64 is processed and the vent depth A of the bush notch 73 is adjusted, the value of the vent length B also changes as the value of the vent depth A changes. There is a problem that it is difficult to adjust only the depth A alone. For the same reason, there is a problem that it is difficult to adjust only the vent length B alone.

  It is an object of the present invention to provide a lock pin bush, a runner lock pin, and an injection mold that can reduce the occurrence frequency of resin burrs and can easily adjust the vent depth and the vent length independently. Objective.

In order to achieve the above object, the lock pin bush in the first invention is provided on the runner stripper plate,
It has a pin hole through which the runner lock pin that holds the resin in the runner is inserted,
A cylindrical lock pin bush in which a gas discharge passage for discharging gas in the runner is formed between the inner peripheral surface of the pin hole and the outer peripheral surface of the runner lock pin,
A gas discharge groove for discharging the gas in the runner is formed on the inner peripheral surface of the pin hole,
One end of the gas discharge groove opens into the runner and the other end communicates with the gas discharge flow path, and the length direction of the gas discharge groove is the same as the axial direction of the runner lock pin.
A narrow channel portion with a smaller channel cross-sectional area than the gas discharge channel is formed by the outer peripheral surface of the runner lock pin and the gas discharge groove,
The narrow channel part opens directly into the runner,
The depth of the gas discharge groove is the vent depth.

  According to this, gas (exhaust gas, air, etc.) in the runner flows into the narrow channel portion from the runner, flows from the narrow channel portion through the gas discharge channel, and is discharged outside the runner. At this time, since the narrow channel portion opens directly into the runner without passing through the conventional enlarged opening, the resin in the runner enters the enlarged opening to form a resin burr. Can be prevented. In addition, since the channel cross-sectional area of the narrow channel part is smaller than the channel cross-sectional area of the gas discharge channel, the resin in the runner is less likely to enter the narrow channel part, thereby generating resin burrs. The frequency can be reduced.

The runner lock pin in the second invention is a runner lock pin inserted through the pin hole of the lock pin bush described in the first invention,
At the tip that faces the runner, there is a resin holder that holds the resin in the runner and a flange that protrudes radially outward,
By the outer peripheral surface of the flange portion and the gas discharge groove, a narrow flow path portion having a flow path cross-sectional area smaller than the gas discharge flow path is formed,
The thickness of the buttocks is the vent length.

  According to this, only the vent length can be easily adjusted independently by processing the runner lock pin and changing the thickness of the collar portion. Moreover, only the vent depth can be easily adjusted independently by processing the lock pin bushing and changing the depth of the gas discharge groove.

  The injection mold according to the third invention is provided with the lock pin bush described in the first invention and the runner lock pin described in the second invention.

  As described above, according to the present invention, the narrow channel portion opens directly into the runner without using the conventional enlarged opening, so that the resin in the runner enters the enlarged opening. Thus, the formation of resin burrs can be prevented. In addition, since the channel cross-sectional area of the narrow channel part is smaller than the channel cross-sectional area of the gas discharge channel, the resin in the runner is less likely to enter the narrow channel part, thereby generating resin burrs. The frequency can be reduced.

  Furthermore, only the vent length can be easily adjusted independently by processing the runner lock pin and changing the thickness of the collar portion. Moreover, only the vent depth can be easily adjusted independently by processing the lock pin bushing and changing the depth of the gas discharge groove.

Embodiments of the present invention will be described below with reference to FIGS.
As shown in FIGS. 1 and 2, reference numeral 1 denotes an injection mold used for resin molding, and a movable side mounting plate 3 that can be moved up and down is disposed below the fixed side mounting plate 2 so as to face the movable side. A receiving plate 4, a movable side plate 5, and the like are provided on the mounting plate 3. Further, a plastic bolt 6 and a support pin 7 are suspended from the fixed side mounting plate 2, and a runner plate 8 and a runner stripper plate 9 are supported on the fixed side mounting plate 2 via the plastic bolt 6. Each of the runner plate 8 and the runner stripper plate 9 is guided by the support pins 7 and can be moved up and down.

  A runner 16 is formed on the runner plate 8. As shown in FIG. 3, a bush insertion hole 17 is formed in the runner stripper plate 9. The bush insertion hole 17 has a small-diameter portion 17a that opens into the runner 16 and a large-diameter portion 17b that opens to the fixed-side mounting plate 2 side. An internal thread is formed on the inner peripheral surface of the large diameter portion 17b.

  A lock pin bush 18 is inserted into the bush insertion hole 17. As shown in FIG. 4, the lock pin bush 18 is a cylindrical member having a pin hole 19. A runner lock pin 21 that holds the resin 20 filled in the runner 16 is inserted into the pin hole 19.

  As shown in FIG. 4 (a), the pin hole 19 of the lock pin bush 18 is formed on the small diameter portion 19 a formed on the distal end side facing the runner 16 and on the proximal end portion side opposite to the runner 16. And a large diameter portion 19b.

  As shown in FIG. 5, the runner lock pin 21 has a resin holder 23 that holds the resin 20 in the runner 16 and a flange portion 24 that projects outward in the radial direction at the tip portion facing the runner 16. A large-diameter portion 25 is provided on the opposite base end portion. Further, in the intermediate portion between the flange portion 24 and the large diameter portion 25, a small diameter portion 26 processed to be thinner than the flange portion 24, and a medium diameter portion that is thicker than the small diameter portion 26 and thinner than the large diameter portion 25. 27 is formed.

  As shown in FIG. 2, the runner stripper plate 12 pushes the resin 20 held by the resin holder 23 of the runner lock pin 21 downward to release it from the resin holder 23. Further, as shown in FIG. 3, the large-diameter portion 25 of the runner lock pin 21 is fitted and fixed to the fixed-side mounting plate 2.

  As shown in FIGS. 3 and 6, the gas in the runner 16 (exhaust gas generated from air, resin 20, etc.) is formed between the inner peripheral surface of the pin hole 19 and the outer peripheral surface of the small diameter portion 26 of the runner lock pin 21. ) Is formed over the entire circumference.

  As shown in FIG. 4, a plurality of gas discharge grooves 31 for discharging the gas in the runner 16 are formed on the inner peripheral surface of the small diameter portion 19 a of the pin hole 19. Each gas discharge groove 31 has a concave cross-sectional shape perpendicular to the axis 21 a of the runner lock pin 21. The length direction of each gas discharge groove 31 is the same as the direction of the axis 21a. As shown in FIG. 3, one end of each gas discharge groove 31 opens into the runner 16 and the other end is the first. It communicates with the gas discharge channel 30.

  As shown in FIG. 7, a plurality of narrow channel portions 33 surrounded by the outer peripheral surface of the flange portion 24 of the runner lock pin 21 and the gas discharge grooves 31 are formed. The channel cross-sectional area of each narrow channel portion 33 is smaller than the channel cross-sectional area of the first gas discharge channel 30 (see FIGS. 3 and 6), and as shown in FIG. The road portion 33 opens directly into the runner 16. As shown in FIG. 7, the depth of each gas discharge groove 31 is a vent depth A, and the thickness of the flange 24 is a vent length B as shown in FIG. 5.

  As shown in FIG. 3, a stop member 35 that fixes the lock pin bush 18 inserted into the bush insertion hole 17 is screwed into the large diameter portion 17 b of the bush insertion hole 17. The stop member 35 is formed in a cylindrical shape having through holes 36 penetrating both end faces, and the medium diameter portion 27 of the runner lock pin 21 is inserted into the through hole 36. A second gas discharge passage 38 is formed over the entire circumference between the inner peripheral surface of the through hole 36 of the stop member 35 and the outer peripheral surface of the medium diameter portion 27 of the runner lock pin 21. Note that the lower end portion of the second gas discharge passage 38 communicates with the upper end portion of the first gas discharge passage 30.

  As shown in FIGS. 1 to 3, a third gas discharge channel 40 is formed in the fixed-side mounting plate 2, and one end of the third gas discharge channel 40 is connected to the bush insertion hole 17. The large diameter portion 17b communicates with the other end portion and communicates with the outer surface of the fixed side mounting plate 2.

Hereinafter, the operation of the above configuration will be described.
When the mold is closed as shown in FIG. 1 and the resin 20 is injected into the cavity 11, as shown in FIGS. 3, 7, and 8, the gas (exhaust gas, air, etc.) in the runner 16 From the inside to the narrow channel portion 33, and from the narrow channel portion 33 through the first gas exhaust channel 30, the second gas exhaust channel 38 and the third gas exhaust channel 40, the injection molding metal It is discharged outside the mold 1.

  At this time, the narrow flow path portion 33 opens directly into the runner 16 without passing through the conventional enlarged opening portion, so that the resin in the runner 16 enters the enlarged opening portion and the resin burrs are formed. The formation can be prevented. Further, since the channel cross-sectional area of each narrow channel portion 33 is smaller than the channel cross-sectional area of the first gas discharge channel 30, the resin 20 in the runner 16 enters the narrow channel portion 33. This makes it difficult to reduce the occurrence frequency of resin burrs.

  5 and 8, only the vent length B can be easily adjusted independently by processing the runner lock pin 21 and changing the thickness of the flange 24. Further, as shown in FIGS. 7 and 8, only the vent depth A can be easily adjusted independently by processing the lock pin bush 18 to change the depth of the gas discharge groove 31.

  After the injection molding, as shown in FIG. 2, the movable side mounting base 3 is lowered to open the mold, whereby the runner plate 8 is separated below the runner stripper plate 9 and the movable side mold plate 5 is moved to the runner. The runner stripper plate 9 is spaced below the plate 8, and further, the runner stripper plate 9 is spaced below the fixed side mounting plate 2. Thereby, the runner stripper plate 9 pushes the resin 20 held by the resin holder 23 of the runner lock pin 21 downward, and the resin 20 is released downward from the resin holder 23.

  Below, the selection method of the vent depth A and the vent length B is demonstrated using following Table 1. FIG. Table 1 shows combinations of the depth of the gas discharge groove 31 corresponding to the vent depth A (see FIG. 7) and the thickness of the flange 24 corresponding to the vent length B (see FIG. 5). .

尚、ガス排出用溝３１の深さ（＝ベント深さＡ）を深くするほど或いは鍔部２４の厚さ（＝ベント長さＢ）を薄くするほど、排気の抵抗が減少する。また、ガス排出用溝３１の深さ（＝ベント深さＡ）を浅くするほど樹脂バリの発生が抑制される。さらに、鍔部２４の厚さ（＝ベント長さＢ）を分厚くするほど、樹脂２０がランナーロックピン２１の樹脂ホルダー２３側から小径部２６側へ回り込む回込現象の発生を抑制することができる。

Note that the exhaust resistance decreases as the depth of the gas discharge groove 31 (= vent depth A) increases or the thickness of the flange 24 (= vent length B) decreases. In addition, the generation of resin burrs is suppressed as the depth of the gas discharge groove 31 (= vent depth A) is decreased. Further, as the thickness of the flange portion 24 (= the vent length B) is increased, the occurrence of the wrapping phenomenon in which the resin 20 turns from the resin holder 23 side to the small diameter portion 26 side of the runner lock pin 21 can be suppressed. .

  According to Table 1, first, resin molding is performed with the combination 1 in which the depth of the gas discharge groove 31 is set to be deep and the thickness of the flange portion 24 is set to be thick. At this time, the state of the generated resin burrs is confirmed, and when the amount of generated resin burrs is large, the gas discharge groove 31 is set to a shallow depth while the thickness of the flange 24 is set to be thick. In step 2, resin molding is performed.

  If the amount of resin burrs generated is within an allowable range, the depth of the gas discharge groove 31 is set to the middle, and the thickness of the flange 24 is set to the middle to reduce the gas exhaust resistance. In combination 5, resin molding is performed. In this way, the depth (= The ideal combination of the vent depth A) and the thickness of the flange 24 (= the vent length B) is sought.

  In the above embodiment, the flange portion 24 is formed on the runner lock pin 21 and the gas discharge groove 31 is formed on the inner peripheral surface of the lock pin bush 18, but the flange portion 24 is formed on the runner 16 of the lock pin bush 18. The gas discharge groove 31 may be formed on the inner peripheral surface of the small diameter portion 17 a of the bush insertion hole 17.

  The present invention is useful for exhaust during molding of an injection mold, and is particularly suitable for molding a high fluidity resin used for injection molding of electronic parts such as connectors and optical semiconductor packages.

The figure which closed the injection mold in embodiment of this invention The same figure showing an injection mold opened Figure of lock pin bush and runner lock pin assembled in the same injection mold (A) is a partially cutaway front view of the lock pin bush, (b) is a view taken along line XX in (a). Runner lock pin illustration XX arrow view in FIG. YY arrow view in FIG. The enlarged view of the end of the injection mold that faces the runner of the runner lock pin and lock pin bush Illustration of lock pin bush and runner lock pin assembled in conventional injection mold Front view of the runner lock pin of the injection mold Front view of lock pin bush of injection mold Same as above, vertical section showing vent depth and vent length of injection mold

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection mold 9 Runner stripper plate 16 Runner 18 Lock pin bush 19 Pin hole 20 Resin 21 Runner lock pin 21a Shaft center 23 Resin holder 24 Gutter part 30 First gas discharge flow path 31 Gas discharge groove 33 Narrow flow path Part A Vent depth B Vent length

Claims (3)

Provided on the runner stripper plate,
It has a pin hole through which the runner lock pin that holds the resin in the runner is inserted,
A cylindrical lock pin bush in which a gas discharge passage for discharging gas in the runner is formed between the inner peripheral surface of the pin hole and the outer peripheral surface of the runner lock pin,
A gas discharge groove for discharging the gas in the runner is formed on the inner peripheral surface of the pin hole,
One end of the gas discharge groove opens into the runner and the other end communicates with the gas discharge flow path, and the length direction of the gas discharge groove is the same as the axial direction of the runner lock pin.
A narrow channel portion with a smaller channel cross-sectional area than the gas discharge channel is formed by the outer peripheral surface of the runner lock pin and the gas discharge groove,
The narrow channel part opens directly into the runner,
A lock pin bushing characterized in that the depth of the gas discharge groove is the vent depth. A runner lock pin inserted into the pin hole of the lock pin bush described in claim 1,
At the tip that faces the runner, there is a resin holder that holds the resin in the runner and a flange that protrudes radially outward,
By the outer peripheral surface of the flange portion and the gas discharge groove, a narrow flow path portion having a flow path cross-sectional area smaller than the gas discharge flow path is formed,
A runner lock pin characterized in that the thickness of the buttocks is the vent length. An injection mold comprising the lock pin bush according to claim 1 and the runner lock pin according to claim 2.

Images