Degassing device for die casting

Abstract

To provide a degassing device for die casting capable of suppressing erosion or the like of a closing piston.SOLUTION: A degassing device 1 for die casting includes a groove-facing-surface 11a that defines a degassing path 10, a pressure-receiving piston 113 that retracts from a position where the pressure-receiving piston has advanced into the degassing path 10 by being pushed by molten metal, a closing piston 118 that is disposed on the downstream side of the pressure-receiving piston 113 and closes the degassing path 10 in conjunction with the retraction of the pressure-receiving piston 113, and a protrusion 119 that is formed on the upstream side of the pressure-receiving piston 113, protrudes in the advancing direction of the pressure-receiving piston 113, and has a front face forming a part of the groove-facing-surface 11a. The protrusion 119 includes an upstream surface 119a intersecting the flow direction of the molten metal entering the degassing path 10, and a downstream surface 119b formed between the upstream surface 119a and the pressure-receiving piston 113 and in the vicinity of the pressure-receiving piston 113.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a degassing device for die casting that degasss the cavity of a die casting mold. [Background technology]

[0002] A degassing device for die casting that degasses the cavity of a die casting mold is known (see, for example, Patent Document 1). The die casting mold is composed of a fixed mold and a movable mold that moves toward and away from the fixed mold. The degassing device includes a fixed block attached to the fixed mold and a movable block attached to the movable mold. When the fixed mold and the movable mold move toward each other to close the die casting mold, the fixed block and the movable block also move toward each other, closing the degassing device. The fixed block and the movable block have path-forming surfaces formed on their mating surfaces that define a degassing path. The path-forming surface is composed of a groove surface formed in one of the fixed block and the movable block and the surface of the other block that faces the groove. The fixed block of the degassing device is equipped with a pressure-receiving piston, a closing piston, an opening / closing lever that transmits the operation of the pressure-receiving piston to the closing piston, and an elastic member that presses the opening / closing lever. The closing piston is located downstream of the pressure-receiving piston in the degassing path. The opening / closing lever is pushed by the elastic member to press the pressure-receiving piston in the advancing direction into the gas vent path.

[0003] When casting begins using a die-casting mold, the cavity of the die-casting mold is filled with molten metal such as aluminum. At that time, the gas inside the cavity is discharged to the outside through the venting passage. After the cavity is filled with molten metal, the molten metal enters the venting passage and pushes the pressure-receiving piston in the backward direction, opposite to the forward direction. This causes the pressure-receiving piston to retreat, and in conjunction with this, the closing piston also retreats, closing the venting passage with its valve body. After casting is complete, the casting, in which the molten metal has solidified, is removed from the venting passage and the die-casting mold. When the casting that was pushing the pressure-receiving piston is removed, the pressure-receiving piston and closing piston are pushed forward by the elastic member. When the closing piston advances, the venting passage is unblocked. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-213372 Summary of the Invention [Problem to be solved by the invention]

[0005] When casting begins, molten metal is supplied to the die-casting mold, causing the die-casting mold to expand due to the heat of the molten metal. However, the molten metal reaches the degassing device only after the entire cavity is filled with molten metal, resulting in a difference in thermal expansion between the die-casting mold and the degassing device in the early stages of casting. Therefore, even if the fixed and movable halves of the die-casting mold are in close contact with each other at their mating surfaces, a gap may form between the mating surfaces of the fixed and movable blocks of the degassing device. If this gap exists and molten metal forcefully enters the degassing path, it may pass through the gap and reach the closing piston before the piston retracts. If the molten metal reaches the closing piston before the piston retracts, the molten metal may adhere to the sliding surface of the valve disc of the closing piston, causing welding or melting damage. Hereinafter, welding or melting damage is referred to as melting damage, etc. Melting damage, etc., on the sliding surface of the valve disc may prevent the closing piston from advancing or retracting normally, or a gap may form between the valve disc and the valve seat, preventing the degassing path from being closed.

[0006] In view of the above circumstances, an object of the present invention is to provide a gas venting device for die casting that can suppress melting damage to the closing piston. [Means for solving the problem]

[0007] The degassing device for die casting of the present invention, which solves the above-mentioned object, is A degassing device for die casting in which a degassing path leading to a cavity of a die casting mold is formed between a fixed block and a movable block, a channel-forming surface defining the vent channel; a pressure-receiving piston that is pushed by the molten metal that has entered the gas venting path and retreats from a position where it has advanced into the gas venting path; a closing piston that is disposed downstream of the pressure-receiving piston in the gas vent path and closes the gas vent path in conjunction with the retraction of the pressure-receiving piston; a protrusion formed upstream of the pressure-receiving piston in the gas vent path, protruding in the advancing direction of the pressure-receiving piston, the protrusion having a surface that forms a part of the path-forming surface, The protrusion has an upstream surface that intersects with the flow direction of the molten metal that has entered the degassing path, and a downstream surface that is formed between the upstream surface and the pressure-receiving piston and in the vicinity of the pressure-receiving piston.

[0008] With this die-casting gas venting device, the flow of molten metal is weakened by the upstream surface, thereby extending the time it takes for the molten metal to reach the closing piston. This makes it easier for the pressure-receiving piston to retreat before the molten metal reaches the closing piston. Even if a gap occurs between the fixed block and the movable block, the weakening of the flow of molten metal and the change in the direction of the flow of molten metal make it difficult for the molten metal to flow into the gap between the fixed block and the movable block. Furthermore, since the downstream surface is formed near the pressure-receiving piston, the flow of molten metal near the pressure-receiving piston changes to a direction that pushes the pressure-receiving piston backward, allowing the pressure-receiving piston to retreat quickly. These factors can prevent melting damage to the closing piston.

[0009] Here, the upstream surface may be a surface with which the molten metal entering the venting path collides. The upstream surface may also be an inclined surface located downstream of the venting path as it advances in the direction of advancement. The downstream surface may guide the molten metal that has passed the protrusion in a direction toward the pressure-receiving piston. The venting path may be configured such that a connecting portion connecting the pressure-receiving piston and the closing piston is a detour path that bypasses the shortest path connecting the pressure-receiving piston and the closing piston in the shortest distance. The protrusion may be located on a straight line connecting the pressure-receiving piston and the closing piston.

[0010] In this die-casting degassing device, A concave portion may be formed in a portion facing the protrusion across the gas vent path, and the concave portion is recessed toward the advancing direction.

[0011] According to this aspect, it is possible to prevent a decrease in the flow rate of the gas flowing through the gas vent path.

[0012] Here, the recess may be recessed in the advancing direction with respect to each of the path forming surfaces on the upstream and downstream sides of the recess in the venting path. The recess may also be disposed upstream of the pressure-receiving piston in the venting path. Additionally, the recess may have an upstream recess surface that intersects with the flow direction of the molten metal that has entered the venting path, and a downstream recess surface that is formed between the upstream recess surface and the pressure-receiving piston and in the vicinity of the pressure-receiving piston. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a gas venting device for die casting that can suppress melting damage to the closing piston. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram of a gas venting device for die casting according to one embodiment of the present invention. [Figure 2] 1A is an end view of the movable block of the degassing device for die casting shown in FIG. 1, as seen from the fixed block side, and FIG. 1B is an end view of the fixed block of the degassing device for die casting shown in FIG. 1, as seen from the movable block side. [Figure 3] 2 is a cross-sectional view of the degassing device for die casting shown in FIG. 1 along the line AA. [Figure 4] FIG. 2 is an explanatory diagram showing a gas venting device for die casting before molten metal enters. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] Fig. 1 is an explanatory diagram of a degassing device 1 for die casting corresponding to one embodiment of the present invention. Fig. 2(a) is an end view of the movable block 12 of the degassing device 1 for die casting shown in Fig. 1, seen from the fixed block 11 side, and Fig. 2(b) is an end view of the fixed block 11 of the degassing device 1 for die casting shown in Fig. 1, seen from the movable block 12 side. In other words, Fig. 2(a) is an end view of the mating surface of the movable block 12, and Fig. 2(b) is an end view of the mating surface of the fixed block 11.

[0017] As shown in Figure 1, the die-casting degassing device 1 is attached to a die-casting mold DM. In Figure 1, a part of the die-casting mold DM is indicated by a two-dot chain line. The die-casting mold DM is composed of a fixed mold DM1 and a movable mold DM2. The space between the fixed mold DM1 and the movable mold DM2 forms a cavity DC. Figure 1 shows the state in which the movable mold DM2 and the fixed mold DM1 are in contact with each other, closing the die-casting mold DM. The movable mold DM2 is configured to be movable in directions approaching and moving away from the fixed mold DM1 (left and right directions in Figure 1).

[0018] The die-casting degassing device 1 is composed of a fixed block 11 attached to the fixed mold DM1 and a movable block 12 attached to the movable mold DM2. When the die-casting mold DM closes, the fixed block 11 and movable block 12 come into contact and the die-casting degassing device 1 also closes. However, if there is a difference in the thermal expansion of the die-casting mold DM and the thermal expansion of the die-casting degassing device 1, the contact surfaces of the fixed block 11 and the movable block 12, which should normally come into contact, may not come into contact with each other, and a gap may form between the contact surfaces.

[0019] A degassing path 10 is formed between the fixed block 11 and the movable block 12, and is connected to the cavity DC of the die-casting mold DM. FIG. 1 shows how molten metal such as aluminum reaches the degassing path 10 formed by the die-casting degassing device 1, and how the degassing path 10 is closed midway by a closing piston 118 (described later). In FIG. 1, the molten metal that has reached the degassing path 10 is indicated by a dotted pattern. In the following description, the upstream side of the degassing path 10 will sometimes be simply referred to as the upstream side, and the downstream side of the degassing path 10 will sometimes be simply referred to as the downstream side. Gas that was in the cavity DC before casting and gas that is generated during casting is discharged to the outside of the die-casting mold DM through this degassing path 10.

[0020] As shown in FIG. 2(a), the movable block 12 has a groove 121 formed therein, which extends continuously from an inlet 10a connected to the cavity DC (see FIG. 1) to a molten metal arrival portion 121b, which is a portion facing the closing piston 118 (see FIG. 1). The upstream portion of the venting path 10 is defined by a groove defining surface 121a that defines the groove 121 and a groove opposing surface 11a (see FIG. 2(b)) of the fixed block 11 that faces the groove 121. In FIG. 2(b), the groove opposing surface 11a is indicated by the area surrounded by a two-dot chain line. The groove defining surface 121a and the groove opposing surface 11a correspond to an example of a path forming surface. During casting, gas flows in from the cavity DC, and then the molten metal enters the upstream portion of the venting path 10.

[0021] As shown in FIG. 2(a), a pressure-receiving facing portion 121c, which faces a pressure-receiving piston 113 (see FIG. 1), is provided on the movable block 12 between the inlet 10a and the molten metal arrival portion 121b on the inlet 10a side. Gas discharged from the cavity DC flows from the inlet 10a into the gas venting path 10 (groove 121) and reaches the molten metal arrival portion 121b via the pressure-receiving facing portion 121c. Slowly after the gas, the molten metal also flows from the inlet 10a into the gas venting path 10 and reaches the molten metal arrival portion 121b via the pressure-receiving facing portion 121c. Note that the gas venting path 10 has a connecting portion connecting the pressure-receiving facing portion 121c and the molten metal arrival portion 121b, which is configured as a detour path that bypasses the shortest path connecting the pressure-receiving facing portion 121c and the molten metal arrival portion 121b. In addition, the connecting portion branches into two at the pressure-receiving facing portion 121c, so that two detour paths are formed.

[0022] 1, the fixed block 11 has a block main body 110, a cover body 111, a pressure-receiving sleeve 112, a pressure-receiving piston 113, an opening / closing lever 114, an urging pin 115, an urging mechanism 116, a closing sleeve 117, a closing piston 118, and a protrusion 119. The block main body 110 is the body of the fixed block 11. The cover body 111 covers the surface of the fixed block 11 opposite to the mating surface with the movable block 12.

[0023] The pressure-receiving sleeve 112 is fixed inside the block main body 110. The pressure-receiving piston 113 is disposed inside the pressure-receiving sleeve 112 and is supported by the pressure-receiving sleeve 112 so as to be movable in an advancing direction (leftward in FIG. 1) advancing into the gas venting path 10 and in a retreating direction (rightward in FIG. 1) opposite to the advancing direction. Hereinafter, the leftward direction in FIG. 1 may be referred to as the advancing direction, and the rightward direction in FIG. 1 may be referred to as the retreating direction. The end face of the pressure-receiving piston 113 in the advancing direction is exposed to the gas venting path 10. The end face of the pressure-receiving piston 113 in the retreating direction is in contact with the opening / closing lever 114.

[0024] The opening / closing lever 114 is swingably supported on the block body 110 by a lever shaft 1141. The swing end portion of the opening / closing lever 114 passes through a sleeve notch 1171 formed on the rearward direction side of the closing sleeve 117 and is inserted into a piston hole 1181 formed in the closing piston 118.

[0025] Two urging pins 115 are provided spaced apart in a direction perpendicular to the plane of the paper in Fig. 1. The number of urging pins 115 is not limited to two and may be any number. Each of these urging pins 115 is inserted into a hole formed in the block main body 110, and is held by the block main body 110 so as to be guided by the hole and movable in the forward and backward directions.

[0026] The biasing mechanism 116 is composed of two springs 1161 and one pin plate 1162. The number of springs 1161 is not limited to two and may be any number. The spring 1161 corresponds to an example of a biasing member. The end face of the biasing pin 115 in the retracting direction is in contact with the pin plate 1162. The spring 1161 is constantly compressed by being sandwiched between the bottom surface of the lid recess 1111 formed in the lid body 111 and the pin plate 1162. As shown in FIG. 2(b), the two springs 1161 are arranged in positions overlapping with the two biasing pins 115 in the advancing / retracting direction. The pin plate 1162 extends in the left-right direction in FIG. 2(b), straddling the positions where the two springs 1161 and the two biasing pins 115 are arranged. The pin plate 1162 and the biasing pin 115 are constantly biased in the advancing direction by the spring 1161. However, as shown in Fig. 1, when the die casting degassing device 1 is in a closed state, the pin plate 1162 and the biasing pin 115 are moved backward against the bias of the spring 1161 as the biasing pin 115 is pushed by the movable block 12. When the pin plate 1162 and the biasing pin 115 are moved backward, the opening / closing lever 114 is free to swing. Then, when the molten metal reaches the pressure-receiving piston 113 and the pressure-receiving piston 113 is pushed by the molten metal, the opening / closing lever 114 swings clockwise in Fig. 1 around the lever shaft 1141 as the swing center axis, as shown in Fig. 1. The action of the molten metal pushing the pressure-receiving piston 113 will be described in detail later.

[0027] The closure sleeve 117 is fixed within the block body 110. This closure sleeve 117 corresponds to an example of a valve seat. The closure piston 118 is disposed inside the closure sleeve 117 and is supported by the closure sleeve 117 so as to be movable in the advancement direction and the retreat direction. The closure piston 118 is disposed downstream of the pressure-receiving piston 113 in the gas vent path 10. The closure piston 118 has a shaft shape with large diameters in the advancement direction and the retreat direction portions and a small diameter in the middle portion. The advancement direction portion is the valve disc 1182, which is the closing portion, and the side surface of the valve disc 1182 is the sliding surface with the closure sleeve 117. The outer diameter of the valve disc 1182 is approximately the same as the inner diameter of the closure sleeve 117. When the closure piston 118 moves in the retreat direction, the valve disc 1182 closes the advancement direction portion of the closure sleeve 117. The closure sleeve 117 and the closure piston 118 form a closure valve that closes and opens (uncloses) the gas vent path 10.

[0028] As described above, the swinging end portion of the opening / closing lever 114 is inserted into the piston hole 1181 of the closing piston 118, so the closing piston 118 moves in the forward and backward directions in response to the swinging of the opening / closing lever 114. That is, when the molten metal reaches the pressure-receiving piston 113 from a position advanced into the gas vent path 10, the pressure-receiving piston 113 is pushed by the molten metal and moves in the backward direction, and in conjunction with this, the opening / closing lever 114 swings clockwise in FIG. 1 , and the closing piston 118 also moves in the backward direction in conjunction with this. When the closing piston 118 moves in the backward direction, the valve disc 1182 enters the closing sleeve 117, and the valve disc 1182 closes the gas vent path 10. This prevents the molten metal from flowing beyond the valve disc 1182 to the downstream side of the gas vent path 10.

[0029] When the gas venting path 10 is not closed by the valve body 1182, the gas that flows from the cavity DC through the inlet 10a into the gas venting path 10 and reaches the closing sleeve 117 passes between the side surface of the valve body 1182 and the closing sleeve 117, flows into an exhaust pipe (not shown), and is discharged to the outside of the gas venting device. In Figure 1, the flow direction of the gas flowing into the exhaust pipe is indicated by an outline arrow.

[0030] The protrusion 119 is formed upstream of the pressure-receiving piston 113 in the venting path 10. The protrusion 119 is a trapezoidal protrusion formed on the movable block 12 so as to protrude beyond the parting line PL formed by the mating surfaces of the fixed block 11 and the movable block 12, and is formed on the block main body 110. That is, the protrusion 119 protrudes in the advancing direction of the pressure-receiving piston 113. The surface of this protrusion 119 forms part of the path-forming surface that defines the venting path 10. The protruding height of this protrusion 119 is preferably 50% or more of the height of the venting path 10 in the advancing direction, such as the inlet 10a, upstream of the position where the protrusion 119 is formed. Note that the protrusion 119 may be formed separately from the block main body 110, as long as it is fixed to the block main body 110.

[0031] An upstream surface 119a of the protrusion 119, which is the surface on the upstream side of the venting path 10, intersects with the flow direction (upward in FIG. 1 ) of the molten metal that has entered the venting path 10 immediately upstream of the protrusion 119. The upstream surface 119a is the upstream surface of the protrusion 119 that connects the base of the protrusion 119 in the retreating direction to the protruding end of the protrusion 119 in the advancing direction. Therefore, the molten metal that has entered the venting path 10 collides with the upstream surface 119a. The upstream surface 119a is an inclined surface that is positioned downstream of the venting path 10 as it approaches the protruding end of the protrusion 119. This makes it easier to remove the solidified metal (cast product) and prevents the flow of the molten metal from suddenly weakening, thereby smoothing the flow of gas and molten metal at the upstream surface 119a.

[0032] A downstream surface 119b, which is the surface of the protrusion 119 on the downstream side in the venting path 10, is formed between the upstream surface 119a and the pressure-receiving piston 113 and in the vicinity of the pressure-receiving piston 113. The downstream surface 119b is the downstream surface of the protrusion 119 that connects the protruding end of the protrusion 119 to the base of the protrusion 119. The downstream surface 119b is an inclined surface located downstream of the venting path 10 as it moves from the protruding end of the protrusion 119 to the base of the protrusion 119. This makes it easier to remove the casting, and the downstream surface 119b can guide the molten metal in the direction toward the pressure-receiving piston 113.

[0033] A recess 1211 recessed in the advancing direction is formed in a portion of the groove 121 formed in the movable block 12 facing the protrusion 119 across the venting path 10. The surface of this recess 1211 forms part of the path forming surface that defines the venting path 10. The height from the edge of the recess 1211 to the bottom surface (the distance in the advancing / retracting direction) is lower than the protruding height of the protrusion 119. The height from the edge of the recess 1211 to the bottom surface is preferably 90 percent to 100 percent of the protruding height of the protrusion 119.

[0034] Fig. 3 is a cross-sectional view taken along the line AA of the degassing device 1 for die casting shown in Fig. 1. In Fig. 3, components of the fixed block 11 other than the block body 110 are not shown.

[0035] 3, in the AA cross section, the gap between the side surface of the protrusion 119 and the groove defining surface 121a of the portion where the recess 1211 is formed is narrow, making it difficult for the molten metal to pass through this gap. For this reason, most of the molten metal that passes through the portion where the recess 1211 is formed flows between the protruding end surface of the protrusion 119 and the bottom surface of the recess 1211.

[0036] When the movable mold DM2 moves away from the fixed mold DM1 shown in FIG. 1, the movable block 12 moves away from the fixed block 11, and the biasing pin 115 and pin plate 1162 move in the advancing direction due to the spring 1161. The opening / closing lever 114 is also pushed by the pin plate 1162 to swing counterclockwise in FIG. 1, and the pressure-receiving piston 113 and the closing piston 118 move in the advancing direction. This causes the valve element 1182 to move away from the inner circumferential surface of the closing sleeve 117, establishing communication between the closing sleeve 117 and the valve element 1182. The casting is then removed from the upstream portion of the degassing path 10. The die-casting degassing device 1 is then closed for the next casting.

[0037] Next, the operation of the degassing device for die casting 1 when molten metal enters the degassing path 10 will be described.

[0038] 4 is an explanatory diagram showing the degassing device for die casting 1 before the molten metal is introduced. In FIG. 4, the die casting mold DM shown in FIG.

[0039] As shown in Figure 4, when the degassing device for die casting 1 is closed and the molten metal has not yet reached the degassing device for die casting 1, the opening / closing lever 114 is in a position swung counterclockwise from the position shown in Figure 1. The pressure-receiving piston 113 and the closing piston 118 are each advanced into the degassing path 10. The biasing pin 115 is pushed by the movable block 12 and moves backward together with the pin plate 1162 against the biasing force of the spring 1161. This allows the opening / closing lever 114 to swing freely.

[0040] The molten metal that enters the degassing path 10 splits once immediately after entering through the inlet 10a, then merges slightly upstream of the protrusion 119, and flows upward in FIG. 4 toward the protrusion 119. When the molten metal reaches the protrusion 119, it collides with the upstream surface 119a of the protrusion 119, causing the flow direction of the molten metal to tilt toward the forward direction and weaken. After passing between the protruding end face of the protrusion 119 and the bottom surface of the recess 1211, the molten metal now flows along the downstream surface 119b of the protrusion 119, tilting toward the backward direction. In FIG. 4, the flow of the molten metal near the protrusion 119 is indicated by thick arrows. The molten metal then reaches the forward end of the pressure-receiving piston 113 and pushes the pressure-receiving piston 113 in the backward direction, causing the pressure-receiving piston 113 to retreat. In conjunction with the retreat of the pressure-receiving piston 113, the opening / closing lever 114 swings clockwise in FIG. 4, and the closing piston 118 also moves in the retreating direction, causing the valve body 1182 to close the gas vent path 10.

[0041] According to this embodiment, the flow of the molten metal that has entered the vent path 10 is weakened by the collision of the molten metal with the upstream surface 119a of the protrusion 119, so the time it takes for the molten metal to reach the closing piston 118 can be extended compared to when the protrusion 119 is not present. The extension of the time it takes for the molten metal to reach the closing piston 118 makes it easier for the closing piston 118 to retract before the molten metal reaches the closing piston 118. Furthermore, if a gap exists between the fixed block 11 and the movable block 12, the fixed block 11 and the movable block 12 thermally expand, reducing the gap before the molten metal reaches the closing piston 118. Furthermore, the weakening of the flow of the molten metal makes it difficult for the molten metal to flow into the gap between the fixed block 11 and the movable block 12. Furthermore, because the direction of the flow of the molten metal changes from a straight line toward the closing piston 118, the molten metal can be prevented from flowing in a straight line toward the closing piston 118 through the gap between the fixed block 11 and the movable block 12 downstream of the portion where the protrusion 119 is formed. In addition, since the downstream surface 119b is formed in the vicinity of the pressure-receiving piston 113, the flow direction is inclined toward the backward direction along the downstream surface 119b of the protrusion 119, and the flow of the molten metal makes it easier to push the pressure-receiving piston 113 in the backward direction. Therefore, the pressure-receiving piston 113 can be quickly and reliably moved backward. As a result, the closing piston 118 can be moved backward before the molten metal reaches the closing piston 118, and therefore, damage such as melting of the valve body 1182 of the closing piston 118 can be suppressed.

[0042] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, in this embodiment, the recess 1211 is formed, but the recess 1211 may be omitted. In the gas vent path 10, the connecting portion connecting the pressure-receiving facing portion 121c and the molten metal arrival portion 121b is branched into two, but it may be formed as a single branch or as three or more branches.

[0043] Even if a constituent element is included only in the description of each of the modified examples described above, that constituent element may be applied to the modified example. [Explanation of symbols]

[0044] 1. Die-casting degassing equipment 10 Gas venting route 11 Fixed Block 11a Groove facing surface (path forming surface) 12 Movable Blocks 113 Pressure-receiving piston 118 Closed Piston 119 protrusion 119a Upstream surface 119b Downstream surface 121a Groove defining surface (path forming surface) DC Cavity DM die-cast mold

Claims

1. A degassing device for die casting in which a degassing path leading to a cavity of a die casting mold is formed between a fixed block and a movable block, a channel forming surface defining the vent channel; a pressure-receiving piston that is pushed by the molten metal that has entered the gas venting path and retreats from a position where it has advanced into the gas venting path; a closing piston that is disposed downstream of the pressure-receiving piston in the gas vent path and closes the gas vent path in conjunction with the retraction of the pressure-receiving piston; a protrusion formed upstream of the pressure-receiving piston in the gas vent path, protruding in the advancing direction of the pressure-receiving piston, the protrusion having a surface that forms a part of the path-forming surface, a downstream surface formed between the upstream surface and the pressure-receiving piston and in the vicinity of the pressure-receiving piston;

2. 2. The gas venting device for die casting according to claim 1, further comprising a recess formed in a portion facing the protrusion across the gas venting path and recessed toward the advancing direction.

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