Patent Grant
11511335
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-057199 filed on Mar. 30, 2021, the contents of which are incorporated herein by reference.
The present invention relates to a gas suction device of a casting mold for sucking gas from a cavity portion of the casting mold.
Vacuum casting systems are known (for example, JP 3969137 B2). In the vacuum casting system, after the gas in the cavity of a casting mold is sucked by a gas suction device, molten metal is injected into the cavity to perform casting. The gas suction device can remove gas (air) in the cavity of the casting mold, thereby reducing gas defects in a cast product caused by the gas mixed into the molten metal.
However, foreign matter (for example, the mold release agent or molten metal powder) sucked into the system together with the gas may interfere with the operation of the system. For example, in the casting system disclosed in JP 3969137 B2, foreign matter may adhere to the shut-off valve on the suction path. Adhesion of foreign matter to the shut-off valve reduces the sealing performance of the shut-off valve. Foreign matter adhering to the shut-off valve can be removed by maintenance operations. However, frequent maintenance reduces the effective operating rate of the casting mold.
As described above, for a gas suction device of a casting mold, it is a task to suppress adhesion of foreign matter to the shut-off valve on the suction path and to efficiently suck gas. An object of the present invention is to achieve this task.
According to an aspect of the present invention, provided is a gas suction device of a casting mold, comprising: an overflow portion connected to a cavity portion of a casting mold and formed along a predetermined surface; a suction path configured to suck gas in the cavity portion via the overflow portion; and a shut-off valve connected between the overflow portion and the suction path and configured to allow the suction path to be blocked, wherein the shut-off valve includes a valve element and a housing section configured to house the valve element, the housing section includes a valve seat portion, an upstream-side housing portion located on an upstream side of the valve seat portion, and a downstream-side housing portion located on a downstream side of the valve seat portion, the valve element includes an abutment portion configured to abut against the valve seat portion to block the suction path, an upstream-side valve portion located on the upstream side of the abutment portion, and a downstream-side valve portion located on the downstream side of the abutment portion, the predetermined surface includes an angle reference surface between the overflow portion and a position where an axis of the valve element intersects the predetermined surface, an angle formed by an axis of the downstream-side housing portion and the angle reference surface is an obtuse angle, the upstream-side housing portion includes an outer peripheral edge having an arc shape on the predetermined surface, the overflow portion includes an introduction path continuous with the upstream-side housing portion and configured to guide the gas to the upstream-side housing portion, and at a predetermined location on the outer peripheral edge, the introduction path is connected to the upstream-side housing portion along a tangential direction of the outer peripheral edge.
According to the present invention, it is possible to provide a gas suction device of a casting mold, which can suppress adhesion of foreign matter to the shut-off valve on the suction path and can efficiently suck gas.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which a preferred embodiment of the present invention is shown by way of illustrative example.
Hereinafter, a gas suction device of a casting mold according to an embodiment of the present invention will be described.
The casting mold 12 is provided with the gas suction device 10. The casting mold 12 includes a movable mold 12a and a fixed mold 12b. The movable mold 12a is disposed on the left side of the fixed mold 12b in the drawing, and can move toward and away from the fixed mold 12b in the lateral direction (horizontal direction) in the drawing. The movable mold 12a and the fixed mold 12b respectively have a mating surface 12a1 and a mating surface 12b1 that face each other. The mating surface 12a1 and the mating surface 12b1 have a concave portion 14a and a concave portion 14b, respectively. The concave portion 14a and the concave portion 14b form a cavity portion 14. The movable mold 12a is moved toward the fixed mold 12b, and the mating surface 12a1 and the mating surface 12b1 are brought into contact with each other, whereby the casting mold 12 is closed. As the casting mold 12 is closed, the cavity portion 14 is formed in the casting mold 12.
The casting mold 12 includes a molten metal supply unit 16. The molten metal supply unit 16 is connected to the fixed mold 12b. The molten metal supply unit 16 supplies molten metal into the cavity portion 14. The fixed mold 12b includes an overflow portion 18 downstream of the cavity portion 14. The overflow portion 18 is connected to the cavity portion 14. The overflow portion 18 extends along the mating surface 12b1 (predetermined surface) of the fixed mold 12b. The molten metal supplied to the cavity portion 14 reaches the overflow portion 18 and then solidifies inside the cavity portion 14 and the overflow portion 18. The solidified molten metal is taken out from the casting mold 12 as a cast product.
The casting mold 12 includes a shut-off valve 20, a suction path 22, and a suction path 24. The shut-off valve 20 is disposed between the overflow portion 18 and the suction path 22, and can block the suction path 22. The shut-off valve 20 is opened and closed by a valve drive unit 28 having a drive shaft 26, thereby preventing the molten metal from entering the suction path 22 from the overflow portion 18.
Typically, a plurality of sets of the overflow portion 18, the shut-off valve 20, and the suction path 22 are connected between the cavity portion 14 and the suction path 24. That is, a plurality of the overflow portions 18 are connected to the cavity portion 14. Further, a plurality of the suction paths 22 are connected to the suction path 24.
The suction path 24 is connected to a gas suction unit 34 through a suction path 30 and a valve V that are disposed outside the casting mold 12. The gas suction unit 34 sucks gas in the cavity portion 14 through the valve V, the suction path 30, the suction path 24, the suction path 22, and the overflow portion 18. A filter 36 is attached to the suction path 30. The filter 36 traps foreign matter in the gas in the suction path 30. The gas suction unit 34 includes a tank 34a and a pump 34b. The gas suction unit 34 sucks gas in the cavity portion 14 by the tank 34a depressurized by the pump 34b. Before supplying the molten metal to the cavity portion 14, the gas suction unit 34 sucks and removes the gas in the cavity portion 14. Thus, gas defects (for example, blow holes) caused by the mixing of gas into the molten metal can be reduced. In addition, trapping foreign matter in the gas by the filter 36 can suppress the reduction of the sealing performance of the shut-off valve 20 caused by adhesion of foreign matter between a valve element 40 and a valve seat portion 42a of the shut-off valve 20.
Here, the suction path 22 and the suction path 24 are connected at an obtuse angle θ1 in the casting mold 12. The angle θ1 is set to enable the suction path 22 to suck the gas in a spiral shape to suppress disturbance of the gas flow in the vicinity of the valve element 40. As a result, the gas can be easily sucked without the foreign matter being retained.
The gas suction unit 34 and an air supply unit 35 are connected to the valve V. The valve V switches between the connection between the suction path 30 and the gas suction unit 34, and the connection between the suction path 30 and the air supply unit 35. By feeding air into the suction path 30 by the air supply unit 35 when the casting mold 12 is opened, the suction path 24, the suction path 22, the shut-off valve 20, and the overflow portion 18 can be air-blown. As a result, the suction path 24, the suction path 22, and the shut-off valve 20 can be cleaned. For example, this air blowing can be performed at the time of opening of the casting mold 12 after the release of a cast product. Instead of using the air supply unit 35, the gas suction unit 34 may supply air to the suction path 30 through the tank 34a from the pump 34b whose operation is reversed.
The suction path 22, the valve element 40 (the abutment portion 40a, the upstream-side valve portion 40b, and the downstream-side valve portion 40c), and the housing section 42 (the valve seat portion 42a, the upstream-side housing portion 42b, and the downstream-side housing portion 42c) have a common axis C0. The axis C0 forms an obtuse angle θ2 with respect to an angle reference surface S. The angle reference surface S is set on the mating surface 12b1 having the overflow portion 18, in order to serve as a reference of the angle θ2. The angle reference surface S is substantially flush with the mating surface 12b1 (predetermined surface). Here, the angle reference surface S is set between a position Q and the overflow portion 18. The position Q is a position where the axis C0 of the valve element 40 and the mating surface 12b1 intersect. The overflow portion 18 is disposed on the mating surface 12b1 (vertical surface) along a vertical line Lp, and basically extends along the vertical line Lp. That is, the angle θ2 is substantially an angle formed by the suction path 22 and the overflow portion 18. Setting the angle θ2 to an obtuse angle suppresses the occurrence of turbulent flow due to a rapid change in the direction in which gas flows. As a result, adhesion and sticking of foreign matter to the valve element 40, the housing section 42, and the suction path 22 are suppressed.
On the other hand, setting the angle θ2 to an acute angle facilitates the occurrence of turbulent flow of gas in the vicinity of the shut-off valve 20. This turbulent flow may cause the foreign matter to collide with the surface of the shut-off valve 20 or the suction path 22, thereby causing the foreign matter to adhere or stick to this surface. The adhered or stuck foreign matter may reduce the sealing performance of the shut-off valve 20. The adhered or stuck foreign matter may clog the shut-off valve 20 or the suction path 22. The reduction in sealing performance means that leakage from the closed shut-off valve 20 occurs.
The overflow portion 18, particularly the introduction path 18b, of the present embodiment has a relatively short linear shape. Unlike the present embodiment, when the introduction path 18b is made to meander in a complicated manner and to be longer, the molten metal is cooled in the introduction path 18b. Thus, the velocity of the molten metal is reduced, and as a result, it is possible to prevent the molten metal from blowing out from the introduction path 18b. Further, foreign matter can be trapped in the introduction path 18b. However, making the introduction path 18b meander and longer increases the capacity of the overflow portion 18, resulting in an increase in the amount of molten metal that is not used for producing the product itself. In the present embodiment, since the introduction path 18b has a relatively short linear shape, the waste of molten metal is reduced. On the other hand, since the amount of foreign matter trapped in the introduction path 18b is reduced, the amount of foreign matter adhering to the shut-off valve 20 increases. In the present embodiment, as will be described later, by devising the shape of the vicinity of the shut-off valve 20, the gas is swirled in the vicinity of the shut-off valve 20. Swirling of the gas suppresses the stagnation of the gas in the vicinity of the shut-off valve, and as a result, prevents the foreign matter from being caught in the shut-off valve 20 (eventually, adhering or sticking to the shut-off valve 20).
The upstream-side housing portion 42b has an arcuate outer peripheral edge P on the mating surface 12b1 (predetermined surface). At a predetermined location on the outer peripheral edge P, the introduction path 18b is connected to the upstream-side housing portion 42b along a tangential direction A of the outer peripheral edge P. As a result, the gas flowing from the introduction path 18b into the upstream-side housing portion 42b forms a swirling flow F. The swirling flow F is a flow of gas swirling along the outer peripheral edge P. While swirling around the axis C0 of the valve element 40 within the housing section 42, the swirling flow F moves downstream of the housing section 42. The gas swirling along the outer peripheral edge P flows along the surfaces of the upstream-side housing portion 42b and the upstream-side valve portion 40b. The swirling of the gas prevents foreign matter in the gas from adhering or sticking to the vicinity of the shut-off valve 20. The foreign matter that has adhered or stuck to the vicinity of the shut-off valve 20 is eventually caught in the seal portion of the shut-off valve 20. The vicinity of the shut-off valve 20 means, for example, the upstream-side housing portion 42b and the upstream-side valve portion 40b.
A central axis C1 of the introduction path 18b extends along the mating surface 12b1 (vertical surface) and forms a predetermined angle θ3 with respect to the vertical line Lp. The introduction path 18b on the left side of
The absolute value and the positive and negative signs of the angles ±θ3 relate to the swirling force and the swirling direction of the swirling flow F. When the absolute value of the angles ±θ3 is larger than 0, the gas swirls easily. The positive and negative signs of the angles ±θ3 relate to the swirling direction. The gas from the introduction path 18b on the left side of
Here, a width W0 of the introduction path 18b is smaller than a diameter R of the outer peripheral edge P (W0<R). Further, the introduction path 18b is connected to the outer peripheral edge P in such a manner that the center axis C1 of the introduction path 18b is shifted from the center of the outer peripheral edge P. As a result, the velocity of the gas flowing from the introduction path 18b into the upstream-side housing portion 42b increases, and consequently, the swirling force of the gas increases. The swirling force more strongly prevents foreign matter in the gas from adhering or sticking to the shut-off valve 20.
The introduction path 18b has a planar bottom surface 18b1 extending along the central axis C1 of the introduction path 18b. The mating surface 12b1 has a connecting portion on which the introduction path 18b and the outer peripheral edge P are connected to each other. A width W1 of the bottom surface 18b1 becomes smaller toward this connection portion. It is noted that, as the width W1 of the introduction path 18b becomes smaller, the depth of the bottom surface 18b1 becomes greater. That is, the cross-sectional area (eventually, the conductance) of the introduction path 18b is substantially constant. Thus, a rapid flow of the gas can be maintained.
Here, in accordance with the swirling of the gas, the foreign matter in the gas swirls, whereby a centrifugal force is applied to the foreign matter in the gas. As a result, there is a possibility that a relatively heavy foreign matter (for example, a powder burr or a solid release agent) in the foreign matter in the gas is separated from the flow of the gas and falls into the upstream-side housing portion 42b. In many cases, the fallen foreign matter does not adhere or stick to the surface of the upstream-side housing portion 42b. Therefore, most of the foreign matter falling on the upstream-side housing portion 42b can be removed relatively easily. For example, by opening the casting mold 12 and air-blowing the casting mold 12 from the gas suction unit 34, the foreign matter on the upstream-side housing portion 42b can be discharged out of the casting mold 12. The upstream-side housing portion 42b is opened downward (downward along the vertical line Lp). Therefore, the foreign matter on the surface of the upstream-side housing portion 42b can be relatively easily removed and discharged by air blowing.
Referring back to
Further, on a plane perpendicular to the axis C0 of the downstream-side housing portion 42c, a gap Gb is defined between the downstream-side housing portion 42c and the downstream-side valve portion 40c. At least when the shut-off valve 20 is in the open state, the cross-sectional area of the gap Gb becomes larger toward the drive shaft 26 within a certain distance from the abutment portion 40a. Thus, occurrence of turbulent flow in the downstream-side housing portion 42c is suppressed. As a result, the swirling flow F of the gas is maintained, and stagnation of the gas in the valve element 40 and the housing section 42 (in this case, the downstream-side valve portion 40c and the downstream-side housing portion 42c) is suppressed. Therefore, separation and adhesion of the foreign matter due to a decrease in the flow rate of the gas are suppressed, and as a result, the foreign matter is prevented from being caught in the shut-off valve 20. Here, the downstream-side valve portion 40c has a truncated cone shape whose diameter decreases toward the drive shaft 26. Thus, the cross-sectional area of the gap Gb becomes larger toward the downstream side of the abutment portion 40a.
In this manner, the gas flowing from the introduction path 18b into the upstream-side housing portion 42b forms the swirling flow F. The swirling flow F swirls along the outer peripheral edge P of the upstream-side housing portion 42b. The swirling flow F flows into the downstream-side housing portion 42c from the upstream-side housing portion 42b. It is noted that, in the downstream-side housing portion 42c according to the present embodiment, the valve element 40 may not include the rib 40d as shown in
Here, when the valve element 40 is viewed in the downstream direction, the angle θ4 is set to be a negative angle (angle of clockwise rotation). As a result, the clockwise swirling flow F is maintained when the valve element 40 is viewed in the downstream direction. That is, the positive and negative signs of the angle θ3 formed by the introduction path 18b and the upstream-side housing portion 42b correspond to the positive and negative signs of the angle θ4 formed by the extending direction of the rib 40d and the reference line L0. As a result, the swirling flow F generated in the upstream-side housing portion 42b is maintained. In addition, the inclination of the rib 40d in the swirling direction of the swirling flow F viewed from the axial direction (X direction) makes it easier to maintain the swirling flow F.
Here, three ribs 40d are arranged along the outer peripheral surface of the downstream-side valve portion 40c. However, the number of the ribs 40d may be an appropriate number of two or more. Thus, providing the ribs in the valve element 40 makes it easier to maintain the swirling flow F of the gas in the downstream-side housing portion 42c.
As described above, in the present embodiment, the gas swirls in the vicinity of the shut-off valve 20. Therefore, the foreign matter in the gas sucked from the cavity portion 14 basically passes through the suction path 22 without adhering or sticking to the shut-off valve 20. Eventually, the foreign matter in the gas is trapped by the filter 36. As a result, the gas suction device 10 can maintain a satisfactory state for a long period of time. As described above, the centrifugal force generated by the swirling of the gas may cause a relatively heavy foreign matter in the gas to fall into the upstream-side housing portion 42b. However, this foreign matter does not adhere or stick to the upstream-side housing portion 42b. Therefore, the foreign matter can be easily removed by air blowing from the gas suction unit 34. Note that the present invention is not limited to the embodiments described above, and various configurations can be adopted therein without departing from the gist of the present invention.
The invention that can be grasped from the above embodiments will be described below.
[1] A gas suction device (10) of a casting mold (12) comprises: an overflow portion (18) connected to a cavity portion (14) of the casting mold and formed along a predetermined surface (mating surface 12b1); a suction path (22) configured to suck gas in the cavity portion via the overflow portion; and a shut-off valve (20) connected between the overflow portion and the suction path and configured to allow the suction path to be blocked, wherein the shut-off valve includes a valve element (40) and a housing section (42) configured to house the valve element, the housing section includes a valve seat portion (42a), an upstream-side housing portion (42b) located on an upstream side of the valve seat portion, and a downstream-side housing portion (42c) located on a downstream side of the valve seat portion, the valve element includes an abutment portion (40a) configured to abut against the valve seat portion to block the suction path, an upstream-side valve portion (40b) located on the upstream side of the abutment portion, and a downstream-side valve portion (40c) located on the downstream side of the abutment portion, the predetermined surface includes an angle reference surface (S) between the overflow portion and a position where an axis (C0) of the valve element intersects the predetermined surface, an angle (θ2) formed by an axis (C0) of the downstream-side housing portion and the angle reference surface is an obtuse angle, the upstream-side housing portion includes an outer peripheral edge (P) having an arc shape on the predetermined surface, and the overflow portion includes an introduction path (18b) continuous with the upstream-side housing portion and configured to guide the gas to the upstream-side housing portion. At a predetermined location on the outer peripheral edge, the introduction path is connected to the upstream-side housing portion along a tangential direction (A) of the outer peripheral edge. As a result, the introduction path of the overflow portion is connected to the upstream-side housing portion of the housing section for housing the valve element and to the arc-shaped outer peripheral edge of the upstream-side housing portion, along the tangential direction of the outer peripheral edge. Therefore, the gas flowing from the introduction path into the upstream-side housing portion forms a swirling flow that swirls along the outer peripheral edge. As a result, it is possible to prevent foreign matter in the gas from colliding with the shut-off valve 20 or the like and adhering or sticking to the shut-off valve 20 or the like. Further, the angle formed by the axis of the downstream-side housing portion and the predetermined surface (angle reference surface) where the overflow portion is formed is set to be an obtuse angle, whereby generation of turbulent flow caused by rapid change of the direction in which the gas flows can be suppressed, and adhesion and sticking of the foreign matter to the shut-off valve or the like can be further suppressed.
[2] A width (W1) of the introduction path is smaller than a diameter (R) of the outer peripheral edge, and the introduction path is connected to the outer peripheral edge in a manner that a central axis (C1) of the introduction path is shifted from a center of the outer peripheral edge. As a result, the swirling force of the gas flowing from the introduction path into the upstream-side housing portion is increased, whereby it is possible to more strongly prevent the foreign matter in the gas from adhering or sticking to the shut-off valve or the like.
[3] The predetermined surface is along a vertical line (Lp), and a central axis of the introduction path is along the predetermined surface and forms a predetermined angle (θ3) with respect to the vertical line. Thus, it is possible to set the swirling force and the swirling direction of the swirling flow.
[4] The introduction path includes a bottom surface (18b1) having a planar shape and extending along a central axis of the introduction path, and a width of the bottom surface becomes smaller toward the predetermined location. This makes it possible to increase the velocity of the gas flowing from the introduction path into the upstream-side housing portion and thus the swirling force, thereby preventing the stagnation of the gas in the vicinity of the valve element, and thus more strongly preventing the foreign matter in the gas from adhering to the shut-off valve or the like and being caught therein.
[5] At least when the shut-off valve is in an open state, a cross-sectional area of a gap (Gb) between the downstream-side housing portion and the downstream-side valve portion on a plane perpendicular to the axis (C0) of the downstream-side housing portion increases from the abutment portion toward the downstream side within a certain distance from the abutment portion. As a result, it is possible to prevent turbulent flow from occurring in the downstream-side housing portion and to prevent the foreign matter in the gas from adhering or sticking to the shut-off valve or the like.
[6] The downstream-side valve portion has a truncated cone shape whose diameter decreases from the abutment portion toward the downstream side. As a result, within a certain distance from the abutment portion, the cross-sectional area of the gap between the downstream-side housing portion and the downstream-side valve portion can be increased with distance from the abutment portion.
[7] The gas flowing from the introduction path into the downstream-side housing portion forms a swirling flow that swirls along the outer peripheral edge, and the downstream-side valve portion includes a rib (40d) extending along a swirling direction of the swirling flow. By adding the rib, the swirling flow of the gas can be further maintained and enhanced.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2021-057199 | Mar 2021 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4852634 | Kawai | Aug 1989 | A |
| Number | Date | Country |
|---|---|---|
| 11-057968 | Mar 1999 | JP |
| 3969137 | Sep 2007 | JP |
| 6765401 | Oct 2020 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20220314309 A1 | Oct 2022 | US |
