Exhaust device for vacuum die casting mold

Abstract

An exhaust device for a vacuum die-casting mold includes a bushing, an ejection pin, and an exhaust pin. The bushing defines a sliding slot extending along an axial direction thereof. The ejection pin includes a head portion and an extension pin portion slidably inserted into the sliding slot. The extension pin portion cooperates with the bushing to define at least one exhaust groove extending along the axial direction in the sliding slot. The exhaust pin includes a head portion and a pin body portion. The head portion defines at least one vent groove extending along a radial direction thereof. The pin body portion defines at least one groove extending along an axial direction thereof. The head portion is pushed by molten metal and gas, and the at least one groove allows only gas to pass therethrough without allowing molten metal to pass therethrough. The passing gas is then exhausted to the outside through the at least one vent groove and the at least one exhaust groove, thereby avoiding the formation of pores on a die-cast product.

Description

Technical Field

[0001] This invention relates to an exhaust device, and more particularly to an exhaust device for a vacuum die-casting mold. Background Technology

[0002] Die casting is a metal casting process that involves injecting molten metal into a mold cavity under high pressure and maintaining that pressure until the metal solidifies. Because the molten metal is injected under high pressure, it easily traps outside air during entry into the mold cavity, leading to porosity and defects in the finished casting. To mitigate this, vacuum die casting technology exists, which extracts air from the mold cavity to reduce air trapping. This technology requires a vacuum valve on the die casting mold, along with a vacuum tank, vacuum pump, vacuum piping, controller, and signal lines. The vacuum pump creates a vacuum environment in the vacuum tank, and when the vacuum valve opens, the negative pressure in the vacuum tank draws air out of the mold cavity. However, vacuum valves have disadvantages such as high manufacturing costs and large size, and also make mold design difficult, thus leaving room for improvement. Summary of the Invention

[0003] The purpose of this invention is to provide a low-cost, small-sized exhaust device that is easy to integrate into a mold.

[0004] The present invention discloses a venting device for a vacuum die-casting mold, comprising a bushing having an inner wall surface, an ejector pin, and a venting pin. The inner wall surface defines a groove extending along its own axial direction. The ejector pin includes a top abutment portion located on one side of the bushing along its axial direction, and an extension pin portion extending from the top abutment portion along its own axial direction and slidably inserted into the groove. The outer peripheral surface of the extension pin portion cooperates with the inner wall surface of the bushing to define at least one venting groove extending axially in the groove. The venting pin includes a head located on the other side of the bushing along its axial direction, and a pin body portion extending from the head along its own axial direction. The head has at least one venting groove extending radially, and the outer peripheral surface of the pin body portion is recessed to form at least one groove extending axially.

[0005] Preferably, in the aforementioned venting device for vacuum die casting molds, the extended pin portion cooperates with the bushing to define a plurality of venting grooves arranged in annular intervals.

[0006] Preferably, in the aforementioned venting device for vacuum die casting mold, the extended pin portion has a plurality of convex surfaces arranged in annular intervals, and a plurality of cross-sections arranged interlaced with and connected to the convex surfaces, each cross-section cooperating with two adjacent convex surfaces and the bushing to define one of the venting grooves.

[0007] Preferably, in the aforementioned venting device for vacuum die casting mold, the bushing includes a tubular enclosure having the inner wall surface, and a fixed wall extending radially outward from one end of the enclosure adjacent to the ejector pin.

[0008] Preferably, in the aforementioned venting device for vacuum die casting mold, the head of the venting pin has a plurality of venting grooves, the venting grooves being arranged in a circumferential ring at intervals, each venting groove having one end facing outwards through the head and one end facing inwards connected to the slide groove.

[0009] Preferably, in the aforementioned venting device for vacuum die casting molds, the pin body of the venting pin has a plurality of grooves arranged in a circumferential ring.

[0010] Preferably, in the aforementioned venting device for vacuum die casting molds, the depth of each groove in the pin portion is 0.1 mm to 0.4 mm.

[0011] Preferably, in the aforementioned venting device for vacuum die casting mold, the head recess forms a positioning groove surrounding the pin portion, and the venting device further includes a sealing ring engaged in the positioning groove.

[0012] The beneficial effects of this invention are as follows: This invention is applicable to vacuum die-casting molds capable of forming boss features. The venting device is disposed within a groove in the vacuum die-casting mold. The front end of the groove has an inner diameter smaller than the groove itself, allowing molten metal from the mold cavity to flow into the feature groove formed as a boss. The bushing is fixed in the groove. The head of the venting pin is located inside the groove and outside the bushing, while the pin body extends through the groove and into the feature groove. When the vacuum die-casting mold is evacuated, the head seals the connection between the groove and the feature groove, preventing external gas from entering the mold cavity through the groove. When molten metal fills the mold cavity, the air and molten metal entering the feature groove push the head towards the bushing, allowing gas to pass through the connection between the groove and the feature groove, then sequentially through at least one groove and at least one venting groove into the slide. Finally, the gas leaves the slide through at least one venting groove and is discharged outwards, achieving the effect of venting gas and preventing porosity in the die-cast part. The molten metal cannot pass through the at least one groove, so it will only fill the space behind the vent pin and will not enter the chute, thus preventing molten metal loss or pipe blockage. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating an embodiment of the venting device for the vacuum die-casting mold of the present invention;

[0014] Figure 2This is an incomplete three-dimensional schematic diagram, which further illustrates the configuration of the various components of the exhaust device;

[0015] Figure 3 This is a perspective view illustrating the bushing of the described embodiment;

[0016] Figure 4 This is a perspective view illustrating the ejector pin of the described embodiment;

[0017] Figure 5 This is a perspective view illustrating the exhaust pin of the described embodiment; and

[0018] Figures 6 to 8 All are sectional views illustrating the operation of the described embodiments. Figures 6 to 8 The sealing ring is not shown. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] See Figure 1 This is an embodiment of the venting device 2 of the vacuum die-casting mold 1 of the present invention. The vacuum die-casting mold 1 includes a mold foot 11 defining an ejection space 111, an ejector plate 12 movably located within the ejection space 111, a movable side mold 13 abutting against the mold foot 11, and a fixed side mold 15 cooperating with the movable side mold 13 to define a mold cavity 14. The mold foot 11 forms a push groove 112 communicating with the ejection space 111, and the movable side mold 13 forms a through groove 131 communicating with the push groove 112, and a feature groove 132 communicating with the through groove 131 and the mold cavity 14. The inner diameter of the through groove 131 is larger than the inner diameter of the feature groove 132, thereby forming a shoulder 133 at the connection between the two. It should be noted that the vacuum die-casting mold 1 may also have multiple push grooves 112, multiple through grooves 131, and multiple feature grooves 132, depending on the number of protrusions to be formed. This necessitates the provision of multiple venting devices 2. Furthermore, this invention relates to venting devices for vacuum die-casting molds; therefore, the vacuum die-casting mold is equipped with a vacuum valve B, as is known to those skilled in the art.

[0021] See Figure 1 , Figure 2 ,and Figure 3 The exhaust device 2 includes a bushing 21 fixed in the through groove 131, an ejector pin 22 with one end located in the ejector space 111 and the other end passing through the pusher groove 112 and inserted into the bushing 21, an exhaust pin 23 slidably located in the through groove 131 and confined between the bushing 21 and the shoulder 133, and a sealing ring 24 disposed on the exhaust pin 23 and facing the shoulder 133 (see Figure 5 The bushing 21 includes a tubular enclosure 211 disposed within the through slot 131, and a fixed wall 212 extending radially outward from one end of the enclosure 211 adjacent to the ejector pin 22. The enclosure 211 has an inner wall surface 213 that defines a groove 214 extending axially around itself. The length of the enclosure 211 is less than the length of the through slot 131, so the enclosure 211 does not touch the shoulder 133 and maintains a distance from the shoulder 133. The fixed wall 212 is locked to the movable side mold 13 by bolts (not shown) or other fasteners, thereby securing the bushing 21.

[0022] See Figure 1 , Figure 2 ,and Figure 4 The ejector pin 22 includes a top abutment portion 221 located on one side of the bushing 21 along the axial direction of the bushing 21, and an extension pin portion 222 extending axially from the top abutment portion 221 and slidably inserted into the slide groove 214. A portion of the top abutment portion 221 is located within the ejection space 111, and another portion extends into the push groove 112. The top abutment portion 221 can be pushed by the ejector plate 12 to drive the extension pin portion 222 to slide within the slide groove 214. The extension pin portion 222 extends through the push groove 112 and is inserted into the slide groove 214. The extension pin portion 222 has four convex surfaces 223 arranged circumferentially at intervals and abutting against the inner wall surface 213, and four cross-sections 224 arranged alternately with and connected to the convex surfaces 223. Each facet 224, in conjunction with two adjacent convex faces 223 and the inner wall surface 213, defines an exhaust groove 225 extending within the slide groove 214. The four exhaust grooves 225 are arranged in a circumferential ring. It should be noted that the facet 224 and the convex faces 223 extend beyond the bushing 21 and partially reside within the push groove 112, allowing the exhaust groove 225 to communicate with the outside. The number and length of the exhaust grooves 225 can be adjusted according to actual needs or the structure of the vacuum die-casting mold 1, and are not limited to the form disclosed in this embodiment. Furthermore, the design of the convex facet 223 abutting against the inner wall surface 213 restricts radial freedom and allows the extension pin 222 to move stably within the slide groove 214. The facet 224 is planar, simplifying processing; however, the facet 224 can also be concave as needed to increase the depth of the exhaust groove 225.

[0023] See Figure 1 , Figure 2 ,and Figure 5The exhaust pin 23 includes a head 231 located on the other side of the bushing 21 along the axial direction of the bushing 21, and a pin portion 232 extending axially from the head 231 and passing through the through groove 131 into the feature groove 132. The head 231 is located within the through groove 131 and confined between the enclosure portion 211 and the shoulder portion 133. The head 231 has four radially extending vent grooves 233 on one surface facing the enclosure portion 211, and the vent grooves 233 are arranged in a circumferentially spaced ring. Each vent groove 233 extends from the outer edge of the head 231 toward the central axis, and its extension length is such that the vent groove 233 is not completely blocked by the enclosure portion 211, but partially communicates with the slide groove 214. The head 231 has a recessed groove 234 on one side facing the shoulder 133, surrounding the pin 232 and into which the sealing ring 24 is engaged. The outer peripheral surface of the pin 232 has recessed grooves 235 extending axially and arranged circumferentially. Each groove 235 has a depth of 0.1 mm to 0.4 mm, a depth that prevents molten metal from passing through but allows gas to pass. The sealing ring 24 is made of silicone, but can also be made of other materials with good airtightness.

[0024] See Figure 2 , Figure 5 ,and Figure 6 When the movable side mold 13 and the fixed side mold 15 are closed, the position in this embodiment is as follows: Figure 6 As shown, at this time, the head 231 is close to the shoulder 133, and the sealing ring 24 is tightly pressed against the shoulder 133 (for ease of illustration and explanation). Figures 6 to 8 (The sealing ring 24 is not shown in the image), thereby sealing the connection between the through groove 131 and the feature groove 132. When the vacuum die-casting mold 1 is evacuated, the outside air flowing out from the slide groove 214 is blocked by the head 231 and the sealing ring 24, thus preventing it from flowing into the feature groove 132. Furthermore, the inward flow of gas causes the head 231 to press even closer to the shoulder 133. This ensures that during vacuuming, outside air will not flow into the mold cavity 14 through the feature groove 132 (see image). Figure 1 ).

[0025] See Figure 1 , Figure 2 ,and Figure 7When molten metal fills the cavity 14, molten metal and air enter the feature groove 132. Since the molten metal cannot pass through the groove 235, as the molten metal gradually fills the feature groove 132 and touches the pin portion 232, the molten metal pushes the pin portion 232 outward. At the same time, the air that can pass through the groove 235 flows along the groove 235 and pushes the head 231 outward. Both of the aforementioned force application methods will cause the head 231 to move towards the enclosure portion 211 and away from the shoulder portion 133. Finally, the head 231 will... Figure 2 and Figure 7 As shown, the pin 23 abuts against the bushing 21 and stops moving. At this time, air first flows into the space between the head 231 and the shoulder 133, then flows into the slide groove 214 through the vent groove 233, and finally flows out of the slide groove 214 through the exhaust groove 225 and is directly discharged to the outside (or discharged to the outside through the push groove 112). This avoids the formation of pores on the die-cast part. The molten metal only fills the space where the exhaust pin 23 moves, but does not pass through the groove 235, achieving the effect of venting without causing the molten metal to leak out. In addition, the molten metal filling the feature groove 132 will eventually form a boss A.

[0026] See Figure 1 , Figure 6 ,and Figure 8 When the mold is opened and the mold is ejected after molding, the ejector plate 12 pushes the top abutment 221 inward, causing the extension pin 222 to move inward along the slide groove 214. This pushes the head 231, causing the vent pin 23 to reset, which in turn causes the sealing ring 24 to press tightly against the shoulder 133 again, and ejects the boss A. When the mold is closed again for the next molding operation, the ejector plate 12 resets outward, causing the ejector pin 22 to return to its original position. Figure 6 The position is repeated to follow the steps described above.

[0027] In summary, the present invention can prevent external air from entering the mold cavity 14 during vacuuming, and can prevent the molten metal from flowing out and allow the gas in the mold cavity 14 to be discharged to the outside during molten metal filling, thereby reducing the gas content of the die-cast parts and improving the yield. In addition, the present invention has a simple structure that can reduce costs, and its small size makes it less susceptible to space limitations of the vacuum die-casting mold 1. It is also easy to manufacture and install, thus effectively achieving the purpose of the present invention.

Claims

1. A venting device for a vacuum die-casting mold, the vacuum die-casting mold comprising a mold foot defining an ejection space, a movable side mold abutting against the mold foot, and a fixed side mold cooperating with the movable side mold to define a cavity, the mold foot forming a push groove communicating with the ejection space, the movable side mold forming a through groove communicating with the push groove, and a feature groove communicating with the through groove and the cavity, the inner diameter of the through groove being larger than the inner diameter of the feature groove, thereby forming a shoulder at the connection between the two, characterized in that: The venting device includes a bushing fixed in the through groove and having an inner wall surface, an ejector pin, an venting pin slidably located in the through groove and confined between the bushing and the shoulder, and a sealing ring. The inner wall surface defines a slide groove extending axially therefrom. The ejector pin includes a top abutment located on one side of the bushing along the axial direction of the bushing, and an extension pin portion extending axially from the top abutment portion and slidably inserted into the slide groove. The outer peripheral surface of the extension pin portion mates with the inner wall surface of the bushing to define an axially extending section in the slide groove. The vent pin includes at least one vent groove extending from the bushing, the vent pin comprising a head located on the other side of the bushing along the axial direction of the bushing, and a pin body extending from the head along its own axial direction, the head having at least one vent groove extending radially, the head having a recessed positioning groove forming a locating groove surrounding the pin body on a face facing the shoulder, the outer peripheral surface of the pin body having a recessed plurality of grooves extending along its own axial direction and arranged in a circumferential ring, each groove having a depth of 0.1 mm to 0.4 mm, and the sealing ring being engaged in the locating groove.

2. The venting device for the vacuum die-casting mold according to claim 1, characterized in that: The extended pin cooperates with the bushing to define a plurality of annularly spaced venting grooves.

3. The venting device for the vacuum die-casting mold according to claim 2, characterized in that: The extension pin has a plurality of convex surfaces arranged in a ring at intervals, and a plurality of cross-sections arranged interlaced with and connected to the convex surfaces. Each cross-section cooperates with two adjacent convex surfaces and the bushing to define one of the exhaust grooves.

4. The venting device for the vacuum die-casting mold according to claim 1, characterized in that: The bushing includes a tubular enclosure portion having the inner wall surface, and a fixed wall portion extending radially outward from one end of the enclosure portion adjacent to the ejector pin.

5. The venting device for the vacuum die-casting mold according to claim 1, characterized in that: The head of the exhaust pin has multiple ventilation slots, which are arranged in a circumferential ring. The outer end of each ventilation slot extends outward through the head, and the inner end connects to the slide groove.

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