JP2011152778A - Venting pin in injection molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the problem that, in the conventional venting method of an ejector pin, for performing exhaust with the outer circumferential part as a passage, owing to the sticking of vaporized decomposed products generated from a gas and an additive, and burrs generated in the case a gas vent is large, the clearance of a sliding part is clogged, thus a working defect is produced. <P>SOLUTION: By locating the passage of venting inside an ejector pin not being close to a sliding part, the exhaust of a gas is performed without causing a problem of a working defect. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a degassing pin in injection molding that manufactures a product by filling a mold with a molten plastic molding material (hereinafter referred to as resin).

In the conventional gas venting method, a gas vent and a gap called gas nigue having a cross-sectional area larger than the cross-sectional area of the gas vent are provided in the divided part or parting surface of the mold part, and the air existing in the mold and The gas generated when the molding material is melted (hereinafter collectively referred to as gas) is discharged out of the mold.
Further, a gas vent and a gap called gas nigue are provided between the outer periphery of the ejector pin and the hole into which the ejector pin is incorporated to discharge the gas out of the mold.

  On the other hand, the Z pin used as a sprue lock pin has a Z-shaped step at the tip, so the effect cannot be achieved even if gas nigging is performed. Absent.

  Hereinafter, a conventional degassing method will be described with reference to FIGS. In the figure, the resin injected from the resin injection port 1 passes through the sprue 2, the sprue lock 3, the runner 4, and the gate 5 to fill the product portion 6. At that time, if the gas is not discharged out of the mold, the product part 6 is not completely filled, and short shots (incomplete shape due to insufficient filling) and gas burns (insufficient gas vents or gas concentration) This may lead to defects such as a phenomenon in which the gas is compressed before the gas vent 7 and becomes a high temperature and the molding material is burnt.

  In order to solve the problem due to insufficient degassing, gas stays in the gas nigue 8 through the gas vent 7 provided in the parting (mold opening / closing surface) 11 of FIG. Then, each time the resin is sequentially filled, gas is pushed out from each gas vent to the gas nigue and discharged out of the mold. (Arrow part a in Figure 1)

  If the above method is insufficient or cannot be divided easily, the gas stays in the gas nigue 15 through the gas vent 14 provided in the ejector pin (the pin that projects the product in the direction of the arrow after filling the resin) 13 in FIG. Every time the resin is filled, gas is pushed out from the gas vent to the gas nigue and discharged out of the mold. (Arrow part b in Fig. 1)

  However, when the dimensions of the gas vents 7, 9, and 14 are small, the effect of degassing is not achieved, or conversely, when the gas vents are large, the resin flows and burrs (thin-walled shape formed by the resin flowing into the gaps of the mold). Surplus).

“Plastic mold parts catalog 2007”, Punch Industry Co., Ltd., 2007, p. 96 “Plastic Mold Standard Parts Catalog 2008”, Misumi Co., Ltd., 2008, p. 60

  When the gas is discharged from the outer periphery of the ejector pin, the gas discharge path and the sliding surface of the ejector pin 13 are close to each other. The gas generated from the resin contains vaporized decomposition products and additives (added to promote the fluidity of the resin), and the mold passes through the gas vent 14 and the gas nigue 15 in FIG. When ejected to the outside, the ejector pin 13 contacts and is cooled, adheres to the outer periphery of the ejector pin 13, and reduces the clearance of the sliding portion, resulting in malfunction of the ejector pin 13.

  Also, when a burr occurs, the clearance of the sliding portion is blocked, resulting in a malfunction.

  The present invention is intended to solve the problem caused by degassing from the ejector pin 13, and it is possible to degas as usual and no malfunction occurs.

  In order to achieve the above object, the present invention engraves the tip of the gas vent ejector pin 16 of FIG. 4 and embeds gas vent pieces 17 and 18 provided with gas vents therein, thereby providing a gas venting path inside. It is provided.

  The degassing ejector pin of the present invention can solve the problem of causing malfunction by providing a degassing path inside.

Partial sectional view of a mold showing the background art of the present invention Parting and enlarged view of the degassing part of the split part (Detailed view of part A in [Fig. 1]) Partial sectional view when ejector pins are used instead of degassing the split part Partial sectional view showing an embodiment of the present invention Drawing of degassing ejector pin Drawing of gas vent piece 17 (two gas vents) Drawing of gas vent piece 18 (one gas vent) Detailed drawing of the structure of the gas vent piece Sectional drawing which shows a mode that a gas vent piece is embedded in a degassing ejector pin Top view after gas vent piece is embedded in vent pin ejector pin Cross-sectional enlarged view showing an embodiment of the degassing ejector pin (detailed view of section C in FIG. 4) Drawing of degassing Z pin Sectional drawing which shows a mode that a gas vent piece is embedded in a degassing Z pin Plan view after the gas vent piece is embedded in the vent pin Z pin Cross-sectional enlarged view showing an embodiment of a degassing Z pin (detailed view of portion D in FIG. 12) Cross section of the tip of the fine hole type degassing ejector pin Plan view of fine hole type degassing ejector pin Plan view of narrow groove type degassing ejector pin Drawing of degassing ejector pin with round engraving Drawing of gas vent holder Gradient processed gas vent piece (1) drawing Gradient processed gas vent piece (2) drawing Top view after embedding a gas vent piece in a round carved degassing ejector pin Sectional drawing which shows embodiment of the degassing ejector pin of circular engraving Drawing of sleeve pin to form product protrusion shape Drawing of a round-engraved degassing ejector pin that has been modified to be combined with a sleeve pin to form a product protrusion Sectional drawing which shows embodiment which combined the degassing ejector pin of the circular engraving additionally machined with the sleeve pin for forming the projection shape of a product

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 5, the length direction of the cylindrical portion and the gas nigue 20 communicating therewith are processed by a fine hole processing machine.

  The tip of the degassing ejector pin 16 is processed by a carving 19 in which a gas vent piece is embedded by an electric discharge machine.

  The gas vent piece 17 shown in FIG. 6 is manufactured by processing two gas vents at two locations, two side surfaces / one bottom surface, and two gas vents, and the gas vent piece 18 shown in FIG. 7 has one gas vent and two side surfaces. Process one gas nigue at the bottom and make one.

  Applying a heat-resistant adhesive to the side portions of the gas vent pieces 17 and 18, as shown in FIGS. 9 and 10, the gas vent piece 17 is arranged at the center and the gas vent pieces 18 are arranged at both ends so that the gas vent faces outward, It is embedded in the engraving 19 and bonded so that four gas vents can be formed.

  When this degassing ejector pin 16 is assembled in a mold and filled with resin, the resin injected from the resin injection port 1 is filled into the product part 6 through the sprue 2, sprue lock 3, runner 4 and gate 5, Is pushed into the back side of the product section 6.

  The gas pushed into the rear side of the product section 6 passes through the gas vent 21 and the gas niger 22 provided in the gas vent pieces 17 and 18 embedded in the gas vent ejector pin 16 shown in FIG. 11 and is provided in the gas vent ejector pin. When the gas stays in the gas nigue 20 and is sequentially filled with the resin, the gas is pushed out from the gas vent to the gas nigue 20 and is discharged from the die space portion shown in FIG.

  In the degassing Z pin, as shown in FIG. 12, the longitudinal direction of the cylindrical portion and the gas nigue 20 communicating therewith are machined by a narrow hole machine and an electric discharge machine.

  The tip of the degassing Z pin 23 is processed by engraving 19 in which a gas vent piece is embedded by an electric discharge machine.

  The gas vent piece 17 shown in FIG. 6 is made by processing two gas vents, two side faces / one bottom face gas nigue, and producing one, and the gas vent piece 18 shown in FIG. 7 has one gas vent and two side faces. Process one gas nigue at the bottom and make one.

  A heat-resistant adhesive is applied to the side portions of the gas vent pieces 17 and 18, and as shown in FIGS. 13 and 14, the gas vent of the gas vent piece 18 is arranged to face outward so that three gas vents can be formed. It is embedded in the engraving 19 and bonded.

  Finally, after filling the groove 24 that has been machined during the engraving process by laser welding, the surplus portion is restored to the state before the engraving process by grinding.

  When this degassing Z pin 23 is assembled in a mold and filled with resin, the resin injected from the resin injection port 1 is filled into the sprue 2 and sprue lock 3, and the gas accumulated in the sprue lock portion is shown in FIG. Gas vents 17 and 18 embedded in the gas vent Z pin 23 shown, gas vents 21 and gas nigues 22 are provided, gas is retained in the gas nigs 20 provided in the gas vent Z pins and gas vents are sequentially filled with resin each time. The gas is pushed out from the mold to the gas nigue and discharged from the mold space shown in FIG.

  In the gas vent machining method, as shown in FIGS. 16 and 17, electric discharge machining was performed without penetrating the gas sink 20 of the gas vent ejector pin 25, and many fine holes were formed in the remaining plate-like portion. A micro-hole type degassing ejector pin is also possible.

  Further, as shown in FIG. 18, a hole (starting hole for wire cutting) 27 having a diameter of about 0.2 mm is formed by a fine hole processing machine instead of the fine hole, and the fine groove 28 is formed by using the wire cutting processing machine. A fine groove type degassing ejector pin which is processed and finally filled with the start hole 27 by laser welding and then ground and smoothed on the upper surface is also possible.

  The method described with reference to FIGS. 16 to 18 can also be applied to the gas vent Z pin 23, and the shapes and processing methods of the fine holes and the fine grooves are merely examples, and the present invention is not limited thereto.

  If burrs are generated unless the gas vent dimensions are reduced due to good resin flow depending on the type of resin, use a gas vent piece type that allows the gas vent dimensions to be set freely. It is preferable to use a fine hole or fine groove type.

  As shown in FIG. 19, in the round engraving degassing ejector pin 29, the length direction of the cylindrical portion and the gas nigue 20 communicating therewith are processed by a fine hole processing machine.

  The engraving 19 for embedding the gas vent piece is processed at the tip of the gas vent ejector pin 29 by a milling machine or an electric discharge machine.

  The chamfer 30 for laser welding is processed by an electric discharge machine.

  One gas vent holder 31 shown in FIG. 20, one drawing shape and one symmetrical shape of the gas vent piece 32 shown in FIG. 21, and one gas vent piece 33 shown in FIG. 22 are manufactured by a wire cutting machine.

  21. One gas vent piece 32 shown in FIG. 21 and one symmetrical shape, and one gas vent piece 33 shown in FIG. 22 can be smoothly discharged, and the gas vent piece processing can be eliminated. Gradient gas vent processing is performed on three surfaces by processing, and chamfering 30 for laser welding is performed.

  The gas vent holder 31 and the gas vent pieces 32 and 33 are inserted into the engraving 19 of the gas vent ejector pin 29, and laser welding is performed on the chamfer 30 in order to prevent the parts from being removed.

  Finally, in order to smooth the flat surface at the tip of the degassing ejector pin 29, grinding is performed.

  When this degassing ejector pin 29 is assembled in a mold and filled with resin, the resin injected from the resin injection port 1 is filled into the product portion 6 through the sprue 2, sprue lock 3, runner 4 and gate 5, Is pushed into the back side of the product section 6.

  The gas pushed into the rear side of the product section 6 passes through the gas vent 21 provided in the gas vent pieces 32 and 33 embedded in the gas vent ejector pins 29 shown in FIG. Each time gas is filled, gas is pushed out from the gas vent to the gas nigue and is discharged from the die space portion shown in FIG.

  In the sleeve pin 34 (hereinafter referred to as a sleeve pin) for forming the protrusion shape of the product, as shown in FIG. 25, the length direction of the cylindrical portion and the gas nigue 20 communicating therewith are processed by a narrow hole processing machine. .

  After a part of the projection shape 35 of the product is processed at the tip of the sleeve pin 34 by an electric discharge machine, a reverse-gradient engraving 36 for forming a space for the purpose of gas nigue is processed by the electric discharge machine.

  When the gas vent pin 29 shown in FIG. 26 is inserted inside, the catch portion 37 is ground so as not to come out.

  As shown in FIG. 26, in order to insert a round-engraved degassing ejector pin 29 into the sleeve pin 34, the brim portion 38 is ground.

  In order to provide the gas vent 39 between the tip end portion and the sleeve pin 34, the tip portion is thinly processed by a grinding process with a dimension corresponding to the type of resin used.

  As a gas nigue, a groove 40 is machined by grinding at a position equivalent to the depth of the reverse-gradient engraving 36 machined on the sleeve pin 34, and the gas nigue communicating with the gas nigue 20 machined inside by a narrow hole processing machine is used. Process.

  When a round-engraved degassing ejector pin 29 processed so as to be inserted inside the sleeve pin 34 is inserted into the sleeve pin 34 as shown in FIG. The injected resin passes through the sprue 2, the sprue lock 3, the runner 4, and the gate 5 and is filled into the product part 6, and the gas is pushed into the back side of the product part 6.

  The gas pushed into the back side of the product part 6 passes through the gas vent 21 provided in the gas vent pieces 32 and 33 embedded in the gas vent ejector pin 29 shown in FIG. 29 is processed and passes through the gas vent 41 provided between the sleeve pin 34 and the gas stays in the gas nigue, and the gas is pushed out from the gas vent to the gas nigue each time the resin is sequentially filled, and the bottom surface or the gas nigue 20 And discharged from the mold space shown in FIG. 1 to the outside of the mold.

DESCRIPTION OF SYMBOLS 1 Resin injection port 2 Sprue 3 Sprue lock 4 Runner 5 Gate 6 Product part 7 Gas vent provided in parting 8 Gas nigue provided in parting 9 Gas vent 10 provided in divided part Gas nigue 11 provided in divided part 11 Parting 12 Divided part 13 Ejector pin 14 Gas vent 15 provided on the ejector pin Gas vent 16 provided on the ejector pin Gas vent ejector pin 17 Gas vent piece 18 Gas vent piece 19 Engraving embedded in the gas vent piece 20 Gas nigue 21 provided on the gas vent ejector pin Gas vent provided on the gas vent piece 22 Gas Nige 23 provided on the Gas Vent Piece Degassing Z Pin 24 Groove 25 Processed and Restored When Carving is Processed 25 Fine Hole Type Degassing Ejector Pin 26 Fine Hole Type Gas vent hole 27 provided in the gas vent ejector pin of the present invention Wire cut machining start hole 28 provided in the fine groove type gas vent ejector pin 28 Gas vent groove 29 provided in the fine groove type gas vent ejector pin 29 Circular engraving gas vent ejector Pin 30 Chamfer 31 for Laser Welding Gas Vent Holder 32 Gas Vent Piece 33 Gradient Processed Gas Vent Part Gas Vent Piece 34 Gradient Processed Gas Vent Part 34 Sleeve Pin 35 for Forming Product Protrusion Shape Product Protrusion Shape 36 Inverse engraving 37 for forming a desired space portion A round-engraved degassing ejector pin 29 that is processed so as to be inserted inside the sleeve pin 34 is a catch portion 38 that prevents it from coming out. Part 39 Gas for engraving Gas vent 40 provided on the vented ejector pin Gas vent groove 41 provided on the gas vented ejector pin engraved in a round shape and gas vent provided between the sleeve pin 34

Claims (7)

In the vent pin for discharging the gas generated by injection molding to the outside,
A gas vent having at least one fine hole extending in a longitudinal direction from a top surface of the cylindrical portion to a predetermined position in the length direction is provided, communicated with the gas vent, and more than a cross-sectional area of the gas vent; A gas nigue having a large cross-sectional area and extending from the predetermined position to the bottom surface of the cylindrical portion or the outer peripheral surface below the predetermined position is provided, and gas is introduced into the gas nigue from the upper surface side through the gas vent, A degassing pin, wherein the degassing pin is discharged out of the mold from the bottom surface or the gas nigue without any other device for assisting the discharge. In claim 1,
In the gas vent, the gas vent is processed into a gradient in order to smoothly discharge the gas. In claim 1 or claim 2,
A gas vent pin, wherein a recess extending from the upper surface to the predetermined position and communicating with the hole is provided, and a gas vent forming component for forming the gas vent is embedded in the recess. In claim 3,
The gas vent pin is characterized in that the gas vent forming part is composed of a plurality of pieces. In claim 1,
As the gas vent, a fine hole or a fine groove is processed in a length portion from the upper surface to the predetermined position.   A degassing pin characterized by combining a degassing pin for discharging a gas generated by injection molding to the outside with a sleeve pin for forming a part of a protruding shape of a product manufactured by injection molding. In any one of Claims 1 thru | or 6.
An ejector pin for extruding a product manufactured by injection molding, or a degassing pin that is a jet pin for sprue lock in injection molding, or a part of the protrusion shape of a product manufactured by injection molding Degassing pin for forming.

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