JP2008068286A - Vacuum die casting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the infiltration of foreign matter such as molten metal residue in a gas exhausted from a gas vent passage in a die casting mold to the outside into a space between a valve guide and a valve stem of a gas vent valve. <P>SOLUTION: The vacuum die casting apparatus is provided with a gas vent valve 34 for opening the opening part 29 of a gas vent passage 28 allowing a cavity to be communicated with the outside when the inside of the cavity is sucked under the reduced pressure and closing the opening part 29 of the gas vent passage 28 when the injection of molten metal is completed. The valve housing 35 of the gas vent valve 34 has an exhaust passage 41 communicated with the opening part 29 of the gas vent passage 28, and the tip of a valve stem 39 freely slidably mounted to a valve guide 36 at the inside is provided with a valve body 38 for opening/closing the gas vent passage 28. The valve stem 39 is provided with an annular member 61 as a shielding member for guiding foreign matter such as molten metal mist blown trough the gas vent passage 28 to the outer part in the radial direction of the exhaust passage 41. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum die casting apparatus for producing a cast product by injecting a molten metal into a cavity mold in a state where the cavity is sucked under reduced pressure.

  The die-casting device is a casting device that injects a molten metal material into a cavity formed in a shape corresponding to the product shape in the die-casting die at a high pressure, and includes a fixed die and a movable die that is abutted against the fixed die. A cavity is formed inside by abutting a fixed mold and a movable mold. Among die casting apparatuses, there is a vacuum die casting apparatus in which the inside of a cavity is sucked under reduced pressure when molten metal is poured in order to prevent defects such as blow holes and pin holes from occurring inside a product during casting. Die-casting equipment is mainly used to produce cast products made of light metals such as aluminum alloys.

As disclosed in Patent Document 1 and Patent Document 2, the vacuum die casting apparatus has a gas vent path that allows the cavity to communicate with the outside. The degassing path communicates with an external vacuum source via a degassing valve attached to the die cast mold, and the opening of the degassing path is opened and closed by the degassing valve. This degassing valve opens the opening of the degassing passage when suctioning the inside of the cavity under reduced pressure, and degassing is performed to prevent the molten metal from flowing out of the degassing passage when the molten metal injection is completed in the mold. Close the opening of the road.
Japanese Utility Model Publication No. 6-23653 Japanese Utility Model Publication No. 5-53762

  The degassing valve has a cylindrical valve housing attached to the opening of the degassing passage. The valve housing is formed with a vacuum port to which a vacuum pipe communicating with a vacuum source is connected, and the vacuum port communicates with a gas vent path in the die cast mold through an exhaust passage in the valve housing. A valve body that opens and closes the gas vent path is provided in the valve housing, and the valve body is provided at the tip of a valve stem that is slidably mounted on a valve guide in the valve housing. At the time of casting, the valve body opens the gas vent passage and releases the gas in the cavity. When the molten metal reaches the valve body, the valve body is closed by the dynamic pressure of the molten metal.

  However, the gas and the molten metal are not completely separated, and the gas containing the mold release agent and molten metal escapes to the degassing path first, and then the molten metal mist and the gas-liquid two-phase fluid escape. Later, the molten metal finally reaches the valve body, and the valve body is closed by the dynamic pressure. When gas escapes from the vent passage through the exhaust passage of the valve housing to the outside, mist-like molten metal in the gas flowing into the exhaust passage of the valve housing may adhere to the valve stem. If it is fixed to the outer peripheral surface of the valve stem, the fixed mist may enter the sliding surface of the valve guide. As described above, when mist adheres to the outer peripheral surface of the valve stem and enters the valve guide, the valve body opens and adheres to the valve guide, and the molten metal leaks to the outside without being closed. A hot water spraying phenomenon will occur.

  An object of the present invention is to prevent foreign matters such as molten metal in the gas discharged to the outside from a die-casting type gas vent path from entering between the valve guide and the valve stem of the gas vent valve.

  Another object of the present invention is to improve the durability of the gas vent valve by preventing foreign matters such as molten metal from entering between the valve guide and the valve stem.

  The vacuum die casting apparatus of the present invention has a die cast mold that forms a cavity having a shape corresponding to a cast product and a gas vent passage that allows the cavity to communicate with the outside. A die casting apparatus for producing a cast product by injecting molten metal into the cavity, wherein when the vacuum is sucked into the cavity, the opening of the degassing path is opened, and when the molten metal injection is completed, the degassing path In the vacuum die casting apparatus provided with a degassing valve for closing the opening of the degassing, the degassing valve is a valve in which an exhaust passage communicating with the opening of the degassing passage and a vacuum port connected to a vacuum source are formed A housing, and a valve stem slidably mounted on a valve guide in the valve housing; A valve body that opens and closes, and a shielding member that is provided in the valve stem and guides foreign matter such as molten metal mist blown through the gas vent passage to the outside in the radial direction of the exhaust passage. Is prevented from entering between the valve stem and the valve guide.

  In the vacuum die casting apparatus of the present invention, the shielding member is an annular member having a tapered surface whose diameter increases from the valve body side toward the valve guide side.

  In the vacuum die casting apparatus of the present invention, the shielding member is a cylindrical member that covers an outer peripheral surface provided in the valve guide.

  According to the present invention, a valve stem provided with a valve body for opening and closing a gas vent path is slidably mounted on a valve guide provided in the valve housing, and the valve stem is provided with a gas vent path. A shielding member is provided to guide the gas containing foreign matter such as molten metal debris to the outside of the valve housing in the radial direction, preventing foreign matter contained in the gas from entering between the valve guide and the valve stem. Is done. Thereby, durability of a gas vent valve can be improved.

  The shielding member can be formed by an annular member having a tapered surface, and can also be a cylindrical member that covers the outer peripheral surface of the valve guide.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a state of a vacuum die casting apparatus according to an embodiment of the present invention before pouring molten metal, and FIG. 2 is a cross-sectional view showing a state after casting of the vacuum die casting apparatus shown in FIG. It is.

  As shown in FIG. 1, the vacuum die casting apparatus 10 includes a fixed mold 11 that is a first mold, and a movable mold 12 that is a second mold that is movable toward and away from the fixed mold 11. The die-casting mold 13 is formed by these molds 11 and 12. Nesting blocks 14 and 15 are incorporated in the fixed mold 11 and the movable mold 12, respectively. When the movable mold 12 and the fixed mold 11 are brought into contact with each other at the respective mold dividing surfaces 16 and 17, respectively. A cavity 18 having a shape corresponding to the shape of the cast product is formed in the die-cast die 13 by the recesses formed in the nesting blocks 14 and 15.

  A sleeve 20 is attached to the fixed mold 11, and a hot water supply port 21 through which molten metal is poured is formed in the sleeve 20. A plunger 23 is inserted into the injection chamber 22 in the sleeve 20 so as to be reciprocally movable in the axial direction. The plunger 23 is attached to a rod 23a of a hydraulic cylinder (not shown). The plunger 23 is axially moved by the hydraulic cylinder. To be driven. FIG. 1 shows a state in which molten metal M is supplied from the hot water supply port 21 into the injection chamber 22. Corresponding to the injection chamber 22, an injection hole 24 reaching the mold dividing surface 16 is formed in the fixed mold 11, and the die cast mold 13 has an injection hole 24 by a recess formed in each mold 11, 12. A communicating runway 25 is formed. Bypass blocks 26 and 27 are incorporated in the fixed mold 11 and the movable mold 12, respectively. When the movable mold 12 and the fixed mold 11 are brought into contact with each other at the respective mold dividing surfaces 16 and 17, respectively. A gas vent path 28 is formed by the recesses formed in the detour blocks 26 and 27, and the gas vent path 28 communicates with the outside through the opening 29.

  A valve raising / lowering cylinder 32 is attached to a support base 31 fixed to the fixed mold 11, and a gas venting valve for opening and closing a gas venting path 28 at the opening 29 portion of the piston rod 33 of the valve lifting / lowering cylinder 32. 34 is provided, and the gas vent valve 34 is attached to the die-cast die 13 with its tip end fitted into the opening 29. The gas vent valve 34 is also called a GF (gas free) valve.

  FIG. 3 is an enlarged cross-sectional view taken along line AA in FIG. The gas vent valve 34 has a valve housing 35 fixed to the piston rod 33. The valve housing 35 has a cylindrical drive part 35a with a bottom on the base end side, a cylindrical fitting part 35b on the distal end side, and a cylindrical guide part 35c with a flange disposed therebetween. These are fastened by bolts (not shown). The degassing valve 34 is attached to the fitting position 35b of the valve housing 35 as shown in FIG. 1 by the valve elevating cylinder 32, and to the opening position 29 of the degassing passage 28 as shown in FIG. The housing 35 reciprocates between the standby position away from the die-cast mold 13.

  As shown in FIG. 3, the gas vent path 28 includes a straight path 28 a that communicates with the central portion of the opening 29, and a detour path 28 b that branches from the straight path 28 a and communicates with the inner peripheral surface of the opening 29. is doing.

  The guide portion 35c of the valve housing 35 has a valve guide 36 disposed on the inner peripheral surface of the fitting portion 35b via a gap, and a guide hole 37 formed in the valve guide 36 has a valve at the tip. A valve stem 39 provided with a body 38 is slidably mounted in the axial direction. When the valve body 38 comes into contact with a valve seat 40 formed on the distal end surface of the valve housing 35, the gas vent passage 28 is closed, When the valve seat 40 is separated, the gas vent passage 28 is opened. A gap between the valve guide 36 and the inner peripheral surface of the fitting portion 35b serves as an exhaust passage 41, and a vacuum port 42 communicating with the exhaust passage 41 has a vacuum pipe communicating with a vacuum tank (not shown) as a vacuum source. 43 is connected. Therefore, when a molten metal material is injected into the cavity 18 to produce a cast product, the valve body 38 is separated from the valve seat 40 and the gas vent passage 28 is opened as shown in FIG. When the exhaust passage 41 is evacuated, the gas vent passage 28 is in a negative pressure state lower than the atmospheric pressure, that is, a vacuum state.

  A piston 44 is fixed to the base end portion of the valve stem 39, and the piston 44 is slidable in a cylinder chamber 45 formed in a drive portion 35 a of the valve housing 35. A supply / discharge port 48 connected to the air pressure source 46 via the air supply pipe 47 is formed in the drive unit 35 a so as to communicate with the cylinder chamber 45. The air supply pipe 47 receives compressed air from the air pressure source 46. An electromagnetic valve 49 for operating to a position for supplying the cylinder chamber 45 and a position for discharging the air in the cylinder chamber 45 to the outside is provided. FIG. 3 shows a state where the compressed air from the air pressure source 46 is supplied into the cylinder chamber 45. When the compressed air is supplied into the cylinder chamber 45, the piston 44 is pressurized and passed through the valve stem 39. Thus, the valve body 38 moves forward and the gas vent path 28 is opened.

  In order to detect that the valve body 38 is opened by the compressed air supplied into the cylinder chamber 45, a small diameter conducting portion 51 is formed in the valve stem 39, and the valve housing 35 is shown in FIG. Thus, when the valve body 38 is in the opened state, the air supply hole 52 facing the conduction portion 51 is formed and the communication hole 53 is formed facing the air supply hole 52. An air supply pipe 55 connected to an air pressure source 46 is connected to an air supply passage 54 formed in the valve housing 35 so as to communicate with the air supply hole 52, and the air supply pipe 55 is compressed from the air pressure source 46. An electromagnetic valve 56 that operates at a position where air is supplied to the air supply hole 52 and a position where air is discharged is provided. In addition, a communication pipe 59 that guides air to the pressure switch 58 is connected to a communication passage 57 formed in the valve housing 35 so as to communicate with the communication hole 53. Accordingly, when the valve body 38 is separated from the valve seat 40 and the gas vent path 28 is opened, the conducting portion 51 is in a position where the air supply hole 52 and the communication hole 53 are communicated, and the compressed air from the air pressure source 46 is supplied. It flows into the communication pipe 59 and the pressure switch 58 detects that the valve body 38 has been opened.

  The valve stem 39 is provided with an annular member 61 as a shielding member. The annular member 61 is formed integrally with the valve body 38 and is attached to the tip of the valve stem 39. A contact surface 38 a that contacts the valve seat 40 is formed on the back surface of the valve body 38, and a tapered surface 38 b that has a small diameter toward the valve stem 39 is formed on the back surface of the valve body 38 in connection with the contact surface 38 a. Has been. The annular member 61 is connected to the tapered surface 38b via a straight portion 62, and has a tapered surface 63 whose diameter increases from a small diameter portion having substantially the same diameter as the straight portion 62 toward the valve guide 36 side.

  The outer diameter of the rear end face 64 of the annular member 61 is substantially the same as the outer diameter of the valve guide 36, and the rear end face 64 faces the tip end face of the valve guide 36 and covers the guide hole 37. Is provided. As a result, when the molten metal is injected into the cavity 18 to manufacture a cast product, as shown by an arrow in FIG. 3, the molten waste, molten metal mist, etc. from the detour path 28 b toward the opening 29 of the gas vent path 28. When a fluid (gas, gas-liquid two-phase fluid) containing foreign matter flows out, the fluid flows into the exhaust passage 41 in a vacuum state. The fluid flowing into the exhaust passage 41 flows toward the radial center of the exhaust passage 41 along the tapered surface 38 b on the back surface of the valve body 38, and then the fitting portion 35 b along the tapered surface 63 of the annular member 61. The gas is guided radially outward so as to collide with the inner peripheral surface of the gas and then discharged from the exhaust passage 41 to the external vacuum tank by the vacuum pipe 43.

  Therefore, foreign matter such as molten metal mist contained in the fluid is prevented from entering between the valve guide 36 and the valve stem 39, and the phenomenon that the valve stem 39 is fixed to the valve guide 36 through the foreign matter is prevented. Can be suppressed.

  In order to manufacture a cast product by the vacuum die casting apparatus 10 described above, as shown in FIG. 1, the movable mold 12 is moved toward the fixed mold 11 so that the molds 11 and 12 are separated from each other. The molds 16 and 17 are matched with each other, and the tip of the valve housing 35 of the gas vent valve 34 is fitted into the opening 29 of the die-cast die 13 by the valve lift cylinder 32. When the solenoid valves 49 and 56 are operated to the positions shown in FIG. 3 to supply the compressed air from the air pressure source 46 to the cylinder chamber 45 and the air supply passage 54, the valve body 38 is vented as shown in FIG. The pressure switch 58 detects that the passage 28 is open and the valve body 38 is open.

  Further, under the state where the cavity 18 and the gas vent passage 28 are evacuated from the vacuum source through the exhaust passage 41, as shown in FIG. 1, the molten metal M heated in the molten state is supplied to the hot water supply port 21. Into the injection chamber 22 and the injection hole 24. Next, when the rod 23 a is driven by a hydraulic cylinder (not shown) and the plunger 23 is driven forward, the molten metal M flows into the cavity 18 from the runner 25 and flows toward the gas vent path 28. Due to the inflow of the molten metal M, gas containing foreign matters such as a mold release agent and molten metal enters the gas vent passage 28 first, and then molten mist and gas-liquid two-phase fluid enter the exhaust gas. It flows into the passage 41 and is discharged to the external vacuum tank by the vacuum pipe 43. When the molten metal M reaches the valve body 38, the dynamic pressure causes the valve body 38 to move backward to a position where it comes into contact with the valve seat 40, the gas vent path 28 is closed, and the molten metal M is prevented from leaking outside.

  During casting, fluid containing foreign matter flows through the exhaust passage 41 until the valve body 38 is closed by the dynamic pressure of the molten metal M, but the fluid is guided by the tapered surface 63 of the annular member 61 to guide the valve stem 39. Therefore, the valve stem 38 is prevented from malfunctioning due to the valve stem 39 being fixed to the valve guide 36, and the durability of the gas vent valve 34 can be improved. . Further, hot water spraying due to the valve opening fixing of the gas vent valve 34 caused by the valve stem 39 being fixed to the valve guide 36 and casting defects due to gas trapping in the cavity 18 during casting due to valve opening fixing are prevented. be able to. When the valve body 38 is closed, the pressure of the compressed air is not applied to the pressure switch 58, so that it is automatically detected that the valve body 38 is closed by a signal from the pressure switch 58.

  4 and 5 are cross-sectional views showing the main part of a vacuum die casting apparatus 10 according to another embodiment of the present invention. FIGS. 4 and 5 correspond to FIG. 3 of the vacuum die casting apparatus 10. A part of the portion is shown, and in FIGS. 4 and 5, members that are the same as those shown in FIG. 3 are given the same reference numerals.

  An annular member 61 as a shielding member is fixed to the valve stem 39 of the gas vent valve 34 shown in FIG. 4 by welding. As described above, the annular member 61 shown in FIG. 3 is formed integrally with the valve body 38, whereas the annular member 61 shown in FIG. The annular member 61 has a tapered surface 63 having a large diameter from the straight portion 62 toward the valve stem 39. Therefore, in the vacuum die casting apparatus 10 shown in FIG. 4 as well, foreign matter contained in the gas discharged to the outside from the gas vent path 28 is prevented from entering the guide hole 37, and the durability of the gas vent valve 34 is improved. Can be made.

  The valve stem 39 of the gas vent valve 34 shown in FIG. 5 is provided with a cylindrical member 65 as a shielding member. A front end portion 65 a of the cylindrical member 65 is fitted and fixed to a large diameter fixing portion 66 formed at the front end portion of the valve stem 39, and a rear end portion 65 b of the cylindrical member 65 is formed in the valve guide 36. It is a shielding part slidably fitted to the straight outer peripheral surface 67. A projection 65 c that contacts the valve stem 39 is provided inside the cylindrical member 65. When the shielding member is the cylindrical member 65, the flow area of the exhaust passage 41 can be made larger than that of the annular member 61, so that the gas flow resistance can be reduced and the degree of vacuum in the mold such as the cavity 18 is improved. Can be made.

  Accordingly, in the vacuum die casting apparatus 10 shown in FIG. 5, the foreign matter contained in the gas discharged to the outside from the gas vent path 28 is prevented from entering the guide hole 37, and the durability of the gas vent valve 34 is improved. Can be made.

  FIG. 6 is a cross-sectional view showing a main part of a vacuum die casting apparatus in which a shielding member is not provided on the valve stem 39 of the gas vent valve 34 as a comparative example. As shown in FIG. 6, in a vacuum die casting apparatus without a shielding member, foreign matter enters the guide hole 37 of the valve guide 36 when an operation of manufacturing 1000 to 1500 shots, that is, a cast product is performed. As a result, the valve guide 36 and the valve stem 39 are fixed, and the valve body 38 may not be closed. If the valve body 38 is not closed, there is a risk that molten metal will leak into the exhaust passage 41, and the gas vent valve 34 has to be replaced before the hot water is generated. On the other hand, in the vacuum die casting apparatus 10 shown in FIG. 3, the valve body 38 is not fixed even after 7093 shots, and the life of the gas vent valve 34 can be greatly extended. .

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the die-casting device includes a hot chamber type in which a molten metal heat-retaining furnace is incorporated, and a cold chamber type in which the heat-retaining furnace is separated. The illustrated die-casting apparatus is a cold chamber type. The present invention can also be applied. The die-cast mold 13 is composed of a fixed mold 11 and a movable mold 12. However, if the two molds 11 and 12 can move relative to and away from each other, both molds 11 can be moved. , 12 may be moved.

It is sectional drawing which shows the state before molten metal injection | pouring of the vacuum die-casting apparatus which is one embodiment of this invention. It is sectional drawing which shows the state after casting of the vacuum die-casting apparatus shown in FIG. It is an expanded sectional view which follows the AA line in FIG. It is sectional drawing which shows the principal part of the vacuum die-casting apparatus which is other embodiment of this invention. It is sectional drawing which shows the principal part of the vacuum die-casting apparatus which is other embodiment of this invention. It is sectional drawing which shows the principal part of the vacuum die-casting apparatus as a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vacuum die-cast apparatus 11 Fixed metal mold | die 12 Movable metal mold | die 13 Die-casting mold 18 Cavity 28 Gas vent path 29 Opening part 34 Gas vent valve 35 Valve housing 36 Valve guide 37 Guide hole 38 Valve body 39 Valve stem 41 Exhaust passage 42 Port 61 Annular member (shielding member)
63 Tapered surface 65 Cylindrical member (shielding member)

Claims (3)

It has a die-cast mold that forms a cavity corresponding to the cast product and a gas vent passage that allows the cavity to communicate with the outside, and the molten metal is injected into the cavity under a vacuum suction state. A vacuum die casting apparatus for manufacturing a cast product, comprising: a degassing valve that opens an opening of the degassing passage when suctioning the inside of the cavity under reduced pressure, and closes the opening of the degassing passage when molten metal injection is completed. In the vacuum die casting equipment provided,
The degassing valve is
A valve housing in which an exhaust passage communicating with an opening of the gas vent passage and a vacuum port connected to a vacuum source are formed;
A valve body that is provided at the tip of a valve stem slidably mounted on a valve guide in the valve housing and opens and closes the gas venting path;
A shielding member that is provided on the valve stem and guides foreign matter such as molten metal mist blown through the gas vent passage to the outside in the radial direction of the exhaust passage;
The vacuum die casting apparatus, wherein the shielding member prevents the foreign matter from entering between the valve stem and the valve guide.   2. The vacuum die casting apparatus according to claim 1, wherein the shielding member is an annular member having a tapered surface whose diameter increases from the valve body side toward the valve guide side.   2. The vacuum die casting apparatus according to claim 1, wherein the shielding member is a cylindrical member that covers an outer peripheral surface provided in the valve guide.

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