Gas-venting path structure for die-casting

Abstract

To provide a gas-venting path structure for die-casting, capable of suppressing seizure, etc. of a closing piston.SOLUTION: A gas-venting path structure 1 for die casting equipped with a gas-venting path 10 connected to a cavity DC of a die casting mold DM includes: a pressure receiving piston 213, one end of which is exposed to the gas-venting path 10 and movable toward the other end; a closing piston 218 which is located downstream of the pressure receiving piston 213 in the gas-venting path 10 and is provided with a closing part 2182 that closes the gas-venting path 10 in conjunction with the movement of the pressure receiving piston 213 toward the other end; and a liquid supply device 5 that discharges a liquid into the gas-venting path 10 from a discharge port 33 formed downstream of the closing part 2182.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a gas venting path structure for die casting, which has a gas venting path connected to a cavity of a die casting mold. [Background technology]

[0002] Conventionally, a gas venting path structure for die casting having a gas venting path is known. The gas venting path is composed of a portion formed by a gas venting device (see, for example, Patent Document 1) arranged at the upstream end portion and a portion extending from that portion toward the downstream side. A vacuum pump is connected to the downstream end of the gas venting path. The gas venting device includes a fixed block and a movable block that approaches and moves away from the fixed block. The fixed block and the movable block form a portion of the gas venting path that is connected to the cavity of the die casting mold. The fixed block of the gas venting device includes 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 opening means that presses the opening / closing lever. The closing piston is arranged downstream of the pressure-receiving piston in the gas venting path. The opening / closing lever is pressed by the opening means to press the pressure-receiving piston and the closing piston toward an opening direction that releases the closing of the closing piston.

[0003] When casting is started using a die-casting mold provided with a gas venting path structure for die-casting, the cavity of the die-casting mold is filled with molten metal such as aluminum. At that time, the gas in the cavity is sucked into the gas venting path, which is made negative pressure by the vacuum pump, and is discharged to the outside through the gas venting path. After the cavity is filled with molten metal, the molten metal enters the gas venting path from the inlet (upstream end) side of the gas venting device for die-casting and pushes the pressure-receiving piston. As a result, the closing piston retreats in the closing direction, and the closing part closes the gas venting path. Note that the closing part here refers to a component part of the closing piston that moves to open and close the gas venting path, and refers to a part that closely contacts the valve seat and performs the closing function of the closing piston when the closing piston retreats. After casting is completed, the casting in which the molten metal has solidified is removed from the gas venting path and the die-casting mold. When the casting that was pushing the pressure-receiving piston is removed, the pressure-receiving piston and the closing piston are pushed forward by the opening means. When the closing piston advances, the gas venting path is opened and communicates with the downstream vacuum pump. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-213372 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in rare cases, due to the occurrence of leading-way melt, the molten metal may reach the closing piston before the closing piston retracts. When the molten metal reaches the closing piston before the closing piston retracts, the molten metal may adhere to the side surface of the closing part or the downstream side surface of the closing part, causing welding, seizure, or melting damage to the closing piston. Hereinafter, welding, seizure, or melting damage is referred to as seizure, etc. As a result of sincere research by the present inventor, it was found that in order to prevent seizure, etc. of the closing part, it is effective to apply a liquid such as a mold release agent to the side surface of the closing part or the downstream side surface of the closing part. However, since the liquid such as the mold release agent is usually applied from the opposing surfaces of the fixed block and the movable block, there are parts on the side surface of the closing part or the downstream side surface of the closing part where the liquid such as the mold release agent does not reach in normal application. For this reason, there is a risk of seizure, etc. occurring in those parts. If seizure, etc. occurs on the side surface of the closing part or the downstream side surface of the closing part, the closing piston cannot retract normally, and the gas venting path may not be opened while the gas venting path is closed, or the gas venting path may not be closed.

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

[0007] The gas venting path structure for die casting of the present invention which solves the above-mentioned object is as follows: A gas venting path structure for die casting, comprising a gas venting path connected to a cavity of a die casting mold, a pressure-receiving piston having one end exposed to the gas vent path and movable toward the other end; a closing piston disposed downstream of the pressure-receiving piston in the gas vent path and provided with a closing portion that closes the gas vent path in response to movement of the pressure-receiving piston toward the other end; and a liquid supply device that discharges liquid into the gas vent path from a discharge port formed on the downstream side of the closing portion.

[0008] According to this gas venting path structure for die casting, liquid is discharged from the downstream side of the closing portion into the gas venting path, so that the liquid can be applied to the side surface of the closing portion and the downstream side surface of the closing portion, thereby suppressing the risk of the closing piston becoming seized.

[0009] Here, the liquid supplying device may be one that ejects liquid toward the upstream side of the degassing path. The liquid supplying device may also be one that ejects a liquid release agent as the liquid. The pressure-receiving piston may be disposed upstream of the closing piston in the degassing path. The pressure-receiving piston may be movable to a side retreating from the degassing path. A suction device may be provided that is connected to a downstream end of the degassing path and that creates a negative pressure in the degassing path. The suction device may have a vacuum pump.

[0010] In this die casting gas venting path structure, The system may further include a gas supply device that discharges gas from the downstream side of the closing portion into the gas vent path.

[0011] By discharging liquid from the liquid supply device and then discharging gas from the gas supply device, it is possible to prevent liquid from flowing into a device such as a suction device that is downstream of the closing piston in the gas vent path.

[0012] Here, the gas supply device may be configured to discharge gas through the discharge port into the gas vent path. Also, the gas supply device may be configured to discharge air as the gas.

[0013] In addition, in this gas venting path structure for die casting, The gas supply device may include an air pressure detection means for detecting the air pressure on the downstream side of the closing portion.

[0014] By detecting the air pressure downstream of the closing portion when the gas supply device discharges gas into the degassing path using the air pressure detection means, it is possible to determine whether the closing piston cannot move forward and the degassing path remains closed by the closing portion even when the casting is removed from the degassing path.

[0015] Furthermore, in this gas venting path structure for die casting, The liquid supply device may include a liquid tank in which the liquid is stored, and an on-off valve disposed between the liquid tank and the discharge port for controlling the amount of the liquid discharged into the gas vent path.

[0016] The on-off valve can prevent liquid from flowing into the gas vent path except when necessary. Here, the on-off valve may be an electrically operated valve. Effect of the Invention

[0017] According to the present invention, it is possible to provide a gas vent path structure for die casting that can suppress seizure of a closing piston and the like. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is an explanatory diagram of a gas venting path structure for die casting according to one embodiment of the present invention. [Diagram 2] 1A is an end view of the movable block of the degassing device provided in the degassing path structure for die casting shown in FIG. 1, as viewed from the fixed block side, and FIG. 1B is an end view of the fixed block of the degassing device provided in the degassing path structure for die casting shown in FIG. 1, as viewed from the movable block side. [Diagram 3] 2 is an explanatory diagram showing a state in which liquid is supplied to a gas venting path from a liquid supplying device provided in the gas venting path structure for die casting shown in FIG. 1. FIG. [Figure 4]10(a) is a system diagram of a liquid supplying device provided in a gas venting path structure for die casting of a first modified example, and FIG. 10(b) is a system diagram of a liquid supplying device provided in a gas venting path structure for die casting of a second modified example. [Diagram 5] FIG. 5 is an explanatory view similar to FIG. 3 of a gas venting path structure for die casting according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] Fig. 1 is an explanatory diagram of a gas venting path structure 1 for die casting corresponding to one embodiment of the present invention. Fig. 2(a) is an end view of a movable block of a gas venting device provided in the gas venting path structure for die casting shown in Fig. 1, seen from the fixed block side, and Fig. 2(b) is an end view of a fixed block of a gas venting device provided in the gas venting path structure for die casting shown in Fig. 1, seen from the movable block side. Note that an exhaust pipe 219 is omitted in Fig. 2(b).

[0021] As shown in FIG. 1, the gas venting path structure 1 for die casting includes a gas venting device 2, a junction block 3, a suction device 4, a liquid supply device 5, and a gas supply device 6. Among these, the gas venting device 2, the junction block 3, and the suction device 4 constitute a gas venting path 10 connected to a cavity DC of a die casting mold DM. FIG. 1 shows a state in which molten metal of a metal such as aluminum reaches an upstream portion of the gas venting path 10 and the gas venting path 10 is closed midway. In FIG. 1, the molten metal that has reached the upstream portion of the gas venting path 10 is shown in a dot pattern. In FIG. 1, the downstream portion of the gas venting path 10 from the junction block 3 is simplified and shown by a solid line. In the following description, the upstream side of the gas venting path 10 may be simply referred to as the upstream side, and the downstream side of the gas venting path 10 may be simply referred to as the downstream side. Gas that was in the cavity DC before casting and gas generated during casting are discharged to the outside of the die casting mold DM through this gas venting path 10.

[0022] The degassing device 2 is attached to the die-casting mold DM. In FIG. 1, a part of the die-casting mold DM is shown 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 becomes a cavity DC. In FIG. 1, the opposed surfaces of the movable mold DM2 and the fixed mold DM1 come into contact with each other to close the die-casting mold DM. The movable mold DM2 is configured to be movable in the direction of separation from the fixed mold DM1 (the left-right direction in FIG. 1). The degassing device 2 is composed of a fixed block 21 attached to the fixed mold DM1 and a movable block 22 attached to the movable mold DM2. When the die-casting mold DM is closed, the opposed surfaces of the fixed block 21 and the movable block 22 come into contact with each other to close the degassing device 2.

[0023] Between the fixed block 21 and the movable block 22, an upstream portion of the gas vent path 10 is formed. This upstream portion is mainly constituted by a groove 221 provided in the movable block 22. In FIG. 2(a), the groove 221 is indicated by cross-hatching. As shown in FIG. 2(a), the groove 221 extends continuously from an inlet 221a connected to the cavity DC (see FIG. 1) to a final destination 221b facing a closing piston 218 described later. Between the inlet 221a and the final destination 221b, a pressure-receiving facing portion 221c facing a pressure-receiving piston 213 described later is provided in the inlet 221a side portion. The gas discharged from the cavity DC flows from the inlet 221a into the groove 221 (gas vent path 10), and reaches the final destination 221b via the pressure-receiving facing portion 221c. Following the gas, the molten metal also flows into the groove 221 from the inlet 221a, passes through the pressure-receiving opposing portion 221c, and reaches the final destination portion 221b.

[0024] 1, the fixed block 21 has a block body 210, a cover body 211, a pressure-receiving sleeve 212, a pressure-receiving piston 213, an opening / closing lever 214, an urging pin 215, an urging mechanism 216, a closing sleeve 217, a closing piston 218, and an exhaust pipe 219. The block body 210 is the framework of the fixed block 21. The cover body 211 closes the surface of the fixed block 21 opposite to the surface facing the movable block 22.

[0025] The pressure-receiving sleeve 212 is fixed inside the block main body 210. The pressure-receiving piston 213 is disposed inside the pressure-receiving sleeve 212 and is supported by the pressure-receiving sleeve 212 so as to be movable in the left-right direction in FIG. 1. One end (the left end in FIG. 1) of the pressure-receiving piston 213 is exposed to the gas venting path 10. In addition, the other end (the right end in FIG. 1) of the pressure-receiving piston 213 is in contact with the opening / closing lever 214 when it is pushed by the molten metal and moved to the right in FIG. 1 as shown in FIG. 1. Hereinafter, the left side in FIG. 1 may be referred to as one end side, and the right side in FIG. 1 may be referred to as the other end side.

[0026] The opening / closing lever 214 is swingably supported on the block body 210 by a lever shaft 2141. The swing end portion of the opening / closing lever 214 passes through a sleeve notch 2171 formed on the other end side of the closing sleeve 217, and is inserted into a piston recess 2181 formed in the closing piston 218.

[0027] Two urging pins 215 are provided spaced apart in a direction perpendicular to the paper surface in Fig. 1. The number of urging pins 215 is not limited to two, and may be any number. Each of these urging pins 215 is provided on the block body 210 so as to be inserted into a hole formed in the block body 210 and to be guided by the hole and movable between one end side and the other end side.

[0028] The biasing mechanism 216 is composed of two springs 2161 and one pin plate 2162. The number of springs 2161 is not limited to two and may be any number. This spring 2161 corresponds to an example of a biasing member. The other end of the biasing pin 215 is in contact with the pin plate 2162. The spring 2161 is always compressed by being sandwiched between the pin plate 2162 and the bottom surface of the cover recess 2111 formed in the cover body 211. As shown in FIG. 2(b), the two springs 2161 are arranged at positions overlapping the two biasing pins 215, respectively, as viewed from one end side. The pin plate 2162 extends in the left-right direction in FIG. 2(b) across the positions where the two springs 2161 and the two biasing pins 215 are arranged. The pin plate 2162 and the biasing pin 215 are biased toward one end by the spring 2161, but when the degassing device 2 is in a closed state as shown in FIG. 1, the biasing pin 215 is pushed by the movable block 22 and moves toward the other end against the bias of the spring 2161. When the pin plate 2162 and the biasing pin 215 move toward the other end, the opening / closing lever 214 becomes swingable. When the molten metal reaches the pressure-receiving opposing portion 221c, the pressure-receiving piston 213 is pushed by the molten metal as shown in FIG. 1, and the opening / closing lever 214 is pushed toward the other end, and swings clockwise in FIG. 1 with the lever shaft 2141 as the swing center axis. Before being pushed by the molten metal, the opening / closing lever 214 is in a position swinging counterclockwise from the position shown in FIG. 1.

[0029] The closure sleeve 217 is fixed inside the block body 210. This closure sleeve 217 corresponds to an example of a valve seat. The closure piston 218 is disposed inside the closure sleeve 217 and is supported by the closure sleeve 217 so as to be movable between one end side and the other end side. The closure piston 218 has a shaft shape with a large diameter at one end side and a small diameter at the middle part. The large diameter one end side part becomes the closure part 2182. The outer diameter of the closure part 2182 is approximately the same as the inner diameter of the closure sleeve 217. The closure part 2182 is disposed downstream of the pressure receiving piston 213. The closure sleeve 217 and the closure piston 218 form a closure valve that closes and opens (uncloses) the gas vent path 10.

[0030] As described above, since the swing end portion of the opening / closing lever 214 is inserted into the piston recess 2181 of the closing piston 218, the closing piston 218 moves to one end side and the other end side in response to the swing of the opening / closing lever 214. That is, when the molten metal reaches the pressure-receiving facing portion 221c, the pressure-receiving piston 213 is pushed by the molten metal and moves to the other end side, and the opening / closing lever 214 swings clockwise in FIG. 1 in conjunction with this, the closing piston 218 moves to the other end side as shown in FIG. 1. When the closing piston 218 moves to the other end side, the closing portion 2182 enters the closing sleeve 217, and the gas venting path 10 is closed by the closing portion 2182. This prevents the molten metal from flowing beyond the closing portion 2182 to the downstream side of the gas venting path 10. The movement of the closing piston 218 to one end side corresponds to the forward movement of the closing piston 218, and the movement of the closing piston 218 to the other end side corresponds to the backward movement of the closing piston 218.

[0031] The exhaust pipe 219 is disposed downstream of the closing portion 2182. When the degassing path 10 is not closed by the closing portion 2182, the gas that flows from the cavity DC through the inlet 221a into the degassing path 10 and reaches the final destination portion 221b passes through the outer side surface of the closing portion 2182, reaches the small diameter portion of the closing piston 218, and then flows into the exhaust pipe 219. In FIG. 1, the flow direction of the gas flowing into the exhaust pipe 219 is indicated by a thick straight arrow.

[0032] The junction block 3 is connected to the downstream end of the exhaust pipe 219. The junction block 3 has a through hole 31 penetrating vertically and a branch hole 32 branching off from the through hole 31 formed therein. This through hole 31 becomes part of the gas venting path 10. The branch hole 32 is formed at an acute angle to the through hole 31 so as to approach the through hole 31 as it moves upstream. The connection between this through hole 31 and the branch hole 32 becomes the discharge port 33. A nozzle 34 capable of spraying liquid and gas toward the discharge port 33 is inserted into the end of the branch hole 32 opposite to the end connected to the through hole 31.

[0033] The suction device 4 is disposed downstream of the junction block 3, and its upstream end is connected to the junction block 3. The suction device 4 has a vacuum pump 41 and a vacuum switching valve 42. The vacuum pump 41 and the vacuum switching valve 42 are controlled by a control device (not shown) and operate in conjunction with the operation of the die-casting mold DM. The vacuum pump 41 is a pump for reducing the pressure in the degassing path 10. By opening the vacuum switching valve 42, the degassing path 10 is reduced in pressure, and the gas in the cavity DC is discharged through the degassing path 10.

[0034] The liquid supplying device 5 supplies liquid such as a liquid release agent or water to the nozzle 34, and discharges the liquid from the discharge port 33 to the degassing path 10 through the nozzle 34 and the branch hole 32. In FIG. 1, the liquid flow path in the liquid supplying device 5 is simplified and shown by solid lines. The liquid supplying device 5 has a pressure tank 51, a first solenoid valve 52, and a check valve 53. The pressure tank 51 corresponds to an example of a liquid tank. The first solenoid valve 52 corresponds to an example of an opening / closing valve. The pressure tank 51 stores liquid therein, and pressure-feeds the stored liquid toward the nozzle 34 side at a predetermined pressure. This liquid is specifically a water-soluble release agent or an oil-based release agent. However, water may be used instead of the release agent, or a liquid other than water may be used. The first solenoid valve 52 is a valve that controls the amount of liquid pumped from the pressure tank 51 to the nozzle 34, i.e., the amount of liquid pumped from the liquid supply device 5 to the degassing path 10. The first solenoid valve 52 is controlled by a control device (not shown) and operates in conjunction with the operation of the die-casting mold DM. In detail, the first solenoid valve 52 is opened when the mold release agent is applied to the die-casting mold DM. The first solenoid valve 52 prevents liquid from flowing into the degassing path 10 except when necessary, and can arbitrarily adjust the amount of liquid supplied to the degassing path 10. The check valve 53 is a valve that prevents the liquid that has passed toward the nozzle 34 from returning to the pressure tank 51.

[0035] The gas supply device 6 supplies gas such as air to the nozzle 34 and discharges the gas from the discharge port 33 to the degassing path 10 through the nozzle 34 and the branch hole 32. Inside the nozzle 34, the flow path of the liquid sent out from the liquid supply device 5 and the flow path of the gas sent out from the gas supply device 6 merge inside. This allows the nozzle 34 to spray either the liquid or the gas from the tip toward the discharge port 33. The gas supply device 6 has a gas compressor 61, a second solenoid valve 62, and an air pressure detection means 63. In FIG. 1, the gas flow path in the gas supply device 6 is simplified and shown by solid lines. The gas compressor 61 compresses the gas. When the second solenoid valve 62 is opened, the compressed gas is supplied toward the nozzle 34 and discharged into the degassing path 10. The second solenoid valve 62 is controlled by a control device (not shown) and is opened for a predetermined time in conjunction with the first solenoid valve 52 being closed after being opened. The vacuum pump 41 and the gas compressor 61 may be a shared one. The air pressure detection means 63 measures the air pressure in the gas path of the gas supply device 6. If the gas vent path 10 remains closed due to a malfunction of the closing piston 218, which will be described in detail later, the air pressure in the gas vent path 10 downstream of the closing part 2182 rises when gas is discharged from the gas supply device 6, and the air pressure in the gas path of the gas supply device 6 also rises. Therefore, the air pressure detection means 63 can detect the malfunction of the closing piston 218. The air pressure detection means 63 may be disposed anywhere between the gas supply device 6 and the closing part 2182 of the closing piston 218, other than the gas path of the gas supply device 6. In other words, the air pressure detection means 63 may be disposed anywhere as long as it is possible to measure the part where the air pressure is equivalent to the air pressure in the gas vent path 10 downstream of the closing part 2182. In other words, the air pressure detection means 63 may be placed anywhere so long as it is possible to measure the air pressure at a position where the air pressure increases due to the gas discharged by the gas supply device 6 when the closing piston 218 operates normally, while suppressing an increase in air pressure, and when the closing piston 218 malfunctions.

[0036] Fig. 3 is an explanatory diagram showing a state in which liquid is supplied to a degassing path from a liquid supplying device provided in the degassing path structure for die casting shown in Fig. 1. In Fig. 3, the die casting mold DM shown in Fig. 1 is omitted.

[0037] When the movable die DM2 is separated from the fixed die DM1 shown in Fig. 1, the movable block 22 is separated from the fixed block 21 as shown in Fig. 3, and the biasing pin 215 and the pin plate 2162 are moved to one end side by the spring 2161. Accordingly, the opening / closing lever 214 is pushed by the pin plate 2162 to swing counterclockwise in Fig. 3, and the pressure-receiving piston 213 and the closing piston 218 are moved to the one end side. As a result, the closing by the closing piston 218 is released and the gas vent path 10 is opened. Specifically, the closing piston 218 moves to the one end side, and the closing portion 2182 is separated from the inner peripheral surface of the closing sleeve 217, and the closing sleeve 217 and the closing portion 2182 are communicated with each other.

[0038] After the movable block 22 is separated from the fixed block 21, the molten metal (cast product) is taken out from the upstream part of the degassing path 10. Then, for the next casting, a mold release agent is applied to the inner surface of the die-casting mold DM that defines the cavity DC shown in FIG. 1 and the inner surfaces of the fixed block 21 and the movable block 22 that define the upstream part of the degassing path 10 by an inner surface application device (not shown). In this embodiment, at that time, a control device (not shown) opens the first solenoid valve 52 and the second solenoid valve 62, so that the liquid is supplied from the liquid supply device 5 and the compressed gas is supplied from the gas supply device 6 at the same time. The supply time of the liquid and the gas can be set arbitrarily, for example, 0.1 seconds. At this time, the vacuum switching valve 42 is closed. The liquid supplied by the liquid supply device 5 is accelerated in the nozzle 34 by the gas supplied from the gas supply device 6 and is discharged from the discharge port 33 to the degassing path 10 together with the gas through the branch hole 32. Because the discharge port 33 opens toward the upstream side, the liquid and gas discharged into the gas venting path 10 flow toward the upstream side, as shown by the white arrow in Fig. 3. The liquid and gas then pass through the through hole 31 and the exhaust pipe 219, reach the small diameter part of the closing sleeve 217 and the closing piston 218, flow toward the closing part 2182, and flow out toward the movable block 22. At that time, part of the liquid adheres evenly to the downstream side (other end side) of the closing part 2182 and the side of the closing part 2182.

[0039] Then, the first solenoid valve 52 is closed. As a result, the supply of liquid from the liquid supply device 5 is stopped, and only gas is supplied from the gas supply device 6. The time for supplying only gas can be set arbitrarily, for example, 0.9 seconds. The gas supplied by the gas supply device 6 is discharged from the discharge port 33 to the degassing path 10 via the nozzle 34 and the branch hole 32. Then, the gas passes through the through hole 31 and the exhaust pipe 219 to reach the small diameter part of the closing sleeve 217 and the closing piston 218, flows to the closing part 2182 side, and is ejected to the one end side through the other end side of the closing part 2182 or the side of the closing part 2182. This prevents excess liquid from remaining in the degassing path 10, and prevents the liquid remaining in the degassing path 10 from flowing into the vacuum pump 41 even when the suction device 4 reduces the pressure in the degassing path 10. In addition, the remaining liquid can be more evenly applied to the downstream side surface of closing portion 2182 and the side surface of closing portion 2182, and excess liquid that has adhered to these areas can be removed.

[0040] As described above, when compressed gas is supplied from the gas supply device 6, the air pressure detection means 63 measures the air pressure in the gas path of the gas supply device 6. If seizure or the like occurs on the side surface of the closing part 2182 or the downstream side surface of the closing part 2182, the movement of the closing piston 218 may be hindered by the seizure or the like. Even if the casting is removed from the upstream part of the gas venting path 10, the closing piston 218 may be unable to move to the one end side while closing the gas venting path 10. In that case, when gas is discharged from the gas supply device 6, the air pressure in the gas venting path 10 downstream of the closing part 2182 and the gas path of the gas supply device increases, so that the air pressure detection means 63 measures the air pressure to detect that the closing piston 218 cannot move.

[0041] According to this embodiment, the liquid is applied from the downstream side of the closing portion 2182 toward the closing portion 2182, so that the liquid can be applied to the portion of the closing piston 218 that faces the vent path 10, such as the side surface of the closing portion 2182 or the downstream side surface of the closing portion 2182. This can reduce the risk of the closing piston 218 becoming seized. In addition, the liquid is evenly applied to the portion of the closing sleeve 217 that faces the vent path 10, so that the risk of the portion becoming seized can also be reduced.

[0042] Next, modified examples of the gas venting path structure 1 for die casting that have been described thus far will be described, focusing on the points that differ from the configurations that have been described thus far.

[0043] FIG. 4(a) is a system diagram of a liquid supplying device provided in a gas venting path structure for die casting of a first modified example, and FIG. 4(b) is a system diagram of a liquid supplying device provided in a gas venting path structure for die casting of a second modified example.

[0044] In these modified examples, the gas venting path structure 1 for die casting includes a plurality of gas venting devices 2 (see FIG. 1) and a junction block 3 (see FIG. 1). The gas venting devices 2 and the junction block 3 are arranged in one die casting mold DM (see FIG. 1). In FIG. 4(a) and FIG. 4(b), the liquid supply device 5, the gas supply device 6, and the nozzles 34 of each junction block 3 in the gas venting path structure 1 for die casting of the modified example are shown. The configuration other than that shown in FIG. 4(a) and FIG. 4(b) is the same as that of the previous embodiment, so that illustrations and detailed explanations are omitted in the description of these modified examples. Note that FIG. 4(a) and FIG. 4(b) show an example in which four gas venting devices 2 and four junction blocks 3 are arranged in the die casting mold DM, but the number of gas venting devices 2 and the number of junction blocks 3 may be arbitrary.

[0045] 4(a), in the gas venting path structure 1 for die casting of the first modified example, a liquid flow path is formed that supplies liquid from a pressure feed tank 51 to four nozzles 34. The liquid flow path branches into four paths beyond a first solenoid valve 52. The branched liquid flow paths are connected to the respective nozzles 34 via check valves 53.

[0046] In addition, gas compressor 61 is also formed with a gas flow path that supplies gas from one gas compressor 61 to four nozzles 34. The gas flow path branches into four paths beyond second solenoid valve 62 and air pressure detection means 63. The branched gas flow paths are connected to the respective nozzles 34.

[0047] The gas venting path structure 1 for die casting of this first modified example also has the same effect as the gas venting path structure for die casting of the previous embodiment. In addition, since only one pressure tank 51, one first solenoid valve 52, and one gas supply device 6 are required for multiple gas venting devices 2 and junction blocks 3, the gas venting path structure for die casting 1 can be constructed at low cost.

[0048] As shown in FIG. 4(b), the gas venting path structure 1 for die casting of the second modified example also has a liquid flow path formed to supply liquid from one pressure tank 51 to four nozzles 34. The liquid flow path branches into four paths between the pressure tank 51 and the four nozzles 34. The first solenoid valve 52 is disposed on the pressure tank 51 side of the nozzles 34 in each of the four branched liquid flow paths. In this second modified example, a check valve 53 is not provided. The gas flow paths from the gas compressor 61 to each nozzle 34 in the gas supply device 6 of the second modified example are similar to those in the first modified example, and therefore will not be described.

[0049] The gas venting path structure 1 for die casting of the second modified example also has the same effect as the gas venting path structure for die casting of the first modified example 1. In addition, since it is possible to spray liquid separately for each nozzle 34, the spray pressure of the liquid sprayed from each nozzle 34 can be increased by spraying the liquid from the nozzles 34 individually.

[0050] Next, a gas venting path structure 1 for die casting according to a second embodiment will be described. In the following description, components having the same names as those described so far will be assigned the same reference numerals as those used so far, and duplicate descriptions may be omitted.

[0051] Fig. 5 is an explanatory view of the gas venting path structure for die casting according to the second embodiment, similar to Fig. 3. In Fig. 5, the movable block 22 shown in Fig. 3 is omitted.

[0052] 5 differs from the gas venting path structure for die casting 1 shown in the previous embodiment mainly in the shape of the junction block 3, the arrangement of the suction device 4, and the arrangement of the gas supply device 6. The gas venting device 2 and the liquid supply device 5 have the same structures as those in the previous embodiment.

[0053] The through hole 31 of the junction block 3 branches into a T-shape within the junction block 3. The suction device 4 is connected to the end of the part of the through hole 31 that branches at a substantially right angle to the part extending vertically. The gas venting path 10 in the junction block 3 of the second embodiment extends from the part connected to the exhaust pipe 219 to the part connected to the suction device 4. The gas supply device 6 is connected to the upper end of the part extending vertically of the through hole 31. The gas supplied from the gas supply device 6 is discharged from the upper end of the through hole 31 through the branching part toward the upstream side into the gas venting path 10 as shown by the thick arrow pointing downward.

[0054] Nozzle 34 has a simple configuration in which only the flow path of the liquid sent out from liquid supply device 5 is connected, and there is no junction with the flow path of the gas. Also, the connection angle of branch hole 32 to the upper and lower extending parts of through hole 31 is slightly larger than that of the previous embodiment.

[0055] The gas venting path structure 1 for die casting of the second embodiment has the same effect as the gas venting path structure 1 for die casting of the previous embodiment. In addition, the gas venting path structure 1 for die casting of the second embodiment has the effect of more reliably preventing liquid from entering the suction device 4. Furthermore, the gas venting path structure 1 for die casting of the second embodiment has the effect of eliminating the need for the special nozzle 34 used in the previous embodiment where the liquid from the liquid supply device 5 and the gas from the gas supply device 6 join together.

[0056] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims. For example, in this embodiment, the liquid from the liquid supply device 5 is discharged to the degassing path 10 via the nozzle 34 and the branch hole 32, but the branch hole 32 may be omitted and the liquid may be discharged from the nozzle 34 to the degassing path 10. In that case, the injection hole of the nozzle 34 becomes the discharge port 33. Also, the nozzle 34 and the branch hole 32 may be omitted and the liquid may be directly discharged from the liquid supply device 5 to the degassing path 10. In that case, the boundary between the liquid supply device 5 and the degassing path 10 becomes the discharge port 33. Also, the position where the liquid is supplied from the liquid supply device 5 may be anywhere downstream of the closing portion 2182, and for example, the discharge port 33 may be provided in the exhaust pipe 219. Similarly, the gas supply device 6 may discharge gas from the nozzle 34 to the degassing path 10, or may directly discharge gas from the gas supply device 6 to the degassing path 10. Furthermore, the position at which gas is supplied from the gas supply device 6 may be anywhere downstream of the closing portion 2182. However, it is preferable that the position is the same as or downstream of the position at which liquid is discharged from the liquid supply device 5 to the gas degassing path 10 so that excess liquid remaining in the gas degassing path 10 can be blown away toward the upstream side. Note that the gas supply device 6 may be omitted if liquid remaining in the gas degassing path 10 does not easily flow into the vacuum pump 41 or if the liquid flowing into the vacuum pump 41 does not affect the vacuum pump 41.

[0057] Although each embodiment and each variant example have been described above, even if a constituent element is included only in the description of each of the described embodiments and variant examples, that constituent element may be applied to other embodiments or other variant examples. [Explanation of symbols]

[0058] 1. Gas venting path structure for die casting 5 Liquid supply device 10 Gas venting route 33 Discharge port 213 Pressure Piston 218 Closed Piston 2182 2182 DC Cavity DM Die-casting mold

Claims

1. A gas venting path structure for die casting, comprising a gas venting path connected to a cavity of a die casting mold, a pressure-receiving piston having one end exposed to the gas vent path and movable toward the other end; a closing piston disposed downstream of the pressure-receiving piston in the gas vent path and provided with a closing portion that closes the gas vent path in response to movement of the pressure-receiving piston toward the other end; a liquid supply device that discharges liquid into the gas venting path from a discharge port formed on the downstream side of the closing portion.

2. 2. The gas venting path structure for die casting according to claim 1, further comprising a gas supplying device for discharging gas from the downstream side of the closing portion into the gas venting path.

3. 3. The gas venting path structure for die casting according to claim 2, wherein the gas supply device has an air pressure detection means for detecting an air pressure on the downstream side of the closing portion.

4. 4. A gas venting path structure for die casting according to claim 1, characterized in that the liquid supply device comprises a liquid tank in which the liquid is stored, and an on-off valve arranged between the liquid tank and the discharge port for controlling the amount of the liquid discharged into the gas venting path.

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