Air extraction device for casting mold

Abstract

The present invention provides an exhaust device for a casting mold. The exhaust device (10) of the casting mold (12) has an overflow portion (18), a suction path (22) and a stop valve (20). The stop valve has a housing portion (42) for housing a valve body. An upstream housing portion (42b) of the housing portion has an arc-shaped outer peripheral edge (P). The overflow portion has an inlet path (18b), which is connected to the upstream housing portion and is used to guide gas to the upstream housing portion. The inlet path is connected to the upstream housing portion at a specified position on the outer peripheral edge along the tangent direction of the outer peripheral edge. Accordingly, it is possible to suppress the adhesion and sticking of foreign matter to the stop valve, etc., and to perform efficient exhaust.

Description

Technical Field

[0001] The present invention relates to a gas extraction device for a casting mold for extracting gas from a mold cavity of the casting mold. Background Art

[0002] A reduced pressure casting system is known (for example, Japanese Patent Publication No. 3969137). In the reduced pressure casting system, after the gas in the mold cavity of the casting mold is sucked out by a vacuum device, molten metal is injected into the mold cavity for casting. The vacuum device removes the gas (air) in the mold cavity of the casting mold, and can reduce gas defects in the casting caused by the gas mixed into the molten metal.

[0003] However, foreign matter (e.g., mold release agent or molten metal powder) sucked into the system together with the gas may hinder the operation of the system. For example, in the casting system of Japanese Patent Gazette No. 3969137, foreign matter sometimes adheres to the shutoff valve on the suction path. Foreign matter attached to the shutoff valve reduces the sealing performance of the shutoff valve. Foreign matter attached to the shutoff valve is removed by maintenance. However, frequent maintenance reduces the actual utilization rate of the casting mold. Summary of the invention

[0004] As described above, a technical problem to be solved is how to prevent foreign matter from adhering to the stop valve on the suction path in the exhaust device of the casting mold and to perform efficient exhaust. The purpose of the present invention is to solve the above technical problem.

[0005] The exhaust device of the casting mold involved in a technical solution of the present invention comprises an overflow portion, a suction path and a stop valve, wherein the overflow portion is connected to the mold cavity portion of the casting mold and is formed along a specified surface; the suction path is used to suck the gas in the mold cavity portion via the overflow portion; the stop valve is connected between the overflow portion and the suction path and can block the suction path, the stop valve comprises a valve body and a receiving portion for receiving the valve body, the receiving portion comprises a valve seat portion, an upstream receiving portion on the upstream side of the valve seat portion, and a downstream receiving portion on the downstream side of the valve seat portion, the valve body comprises an abutment portion, an upstream valve portion and a downstream valve portion, wherein the abutment portion and the valve The seat portion abuts to block the suction path; the upstream valve portion is closer to the upstream side than the abutting portion; the downstream valve portion is closer to the downstream side than the abutting portion, the specified surface has an angle reference surface between the overflow portion and the position where the axis of the valve body intersects the specified surface, the angle between the axis of the downstream side receiving portion and the angle reference surface is an obtuse angle, the upstream side receiving portion has an arc-shaped outer peripheral edge on the specified surface, the overflow portion has an inlet path, the inlet path is connected to the upstream side receiving portion and is used to guide the gas to the upstream side receiving portion, and the inlet path is connected to the upstream side receiving portion at a specified position on the outer peripheral edge along the tangent direction of the outer peripheral edge.

[0006] According to the present invention, it is possible to provide an exhaust device for a casting mold that can efficiently exhaust air while suppressing adhesion of foreign matter to a stop valve on an exhaust path.

[0007] The above-mentioned objects, features and advantages will be easily understood through the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a diagram showing an exhaust device of a casting mold according to an embodiment of the present invention.

[0009] Figure 2 This is an enlarged view showing the stop valve and its vicinity.

[0010] Figure 3 This is a diagram showing a state where the stop valve is viewed from the movable mold side.

[0011] Figure 4 It is a diagram showing an enlarged view of a valve body of a stop valve according to a modified example.

[0012] Figure 5 It refers to the angle observed from the downstream direction along the axis of the valve body. Figure 4 Diagram of the state of the valve body. DETAILED DESCRIPTION

[0013] Next, an exhaust device for a casting mold according to an embodiment of the present invention will be described. Figure 1 It is a diagram showing an exhaust device 10 of a casting mold 12 according to an embodiment of the present invention.

[0014] The casting mold 12 has an exhaust device 10. The casting mold 12 has a movable mold 12a and a fixed mold 12b. The movable mold 12a is arranged on the left side of the fixed mold 12b in the figure, and can move forward and backward in the lateral direction (horizontal direction) in the figure relative to the fixed mold 12b. The movable mold 12a and the fixed mold 12b respectively have a mating surface 12a1 and a mating surface 12b1 facing each other. The mating surface 12a1 and the mating surface 12b1 respectively have a recess 14a and a recess 14b. The recess 14a and the recess 14b constitute a cavity portion 14. By moving the movable mold 12a forward toward the fixed mold 12b, the mating surface 12a1 and the mating surface 12b1 are brought into contact with each other, thereby closing the casting mold 12. As the casting mold 12 is closed, a cavity portion 14 is formed inside the casting mold 12.

[0015] The casting mold 12 has a molten metal supply portion 16. The molten metal supply portion 16 is connected to the fixed mold 12b. The molten metal supply portion 16 supplies molten metal into the cavity portion 14. The fixed mold 12b has an overflow portion 18 on the downstream side 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 (prescribed 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 of the casting mold 12 as a casting.

[0016] The casting mold 12 includes a stop valve 20, a suction path 22, and a suction path 24. The stop valve 20 is disposed between the overflow portion 18 and the suction path 22, and can block the suction path 22. The stop valve 20 is opened and closed by a valve drive portion 28 having a drive shaft 26, and is used to prevent molten metal from intruding from the overflow portion 18 into the suction path 22.

[0017] Typically, a plurality of overflow portions 18, stop valves 20, and suction paths 22 are connected between the cavity portion 14 and the suction path 24. That is, a plurality of overflow portions 18 are connected to the cavity portion 14. In addition, a plurality of suction paths 22 are connected to the suction path 24.

[0018] The suction path 24 is connected to the exhaust section 34 via the suction path 30 and the valve V arranged on the outside of the casting mold 12. The exhaust section 34 sucks the gas in the cavity section 14 via the valve V, the suction path 30, the suction path 24, the suction path 22 and the overflow section 18. A filter 36 is installed on the suction path 30. The filter 36 captures foreign matter in the gas in the suction path 30. The exhaust section 34 has a storage tank 34a and a pump 34b. The exhaust section 34 uses the storage tank 34a after the pressure is reduced by the pump 34b to suck the gas in the cavity section 14. Before the molten metal is supplied to the cavity section 14, the exhaust section 34 sucks and removes the gas in the cavity section 14. Accordingly, gas defects (such as pores) caused by gas mixing into the molten metal can be reduced. Furthermore, by capturing foreign matter in the gas by the filter 36 , it is possible to suppress a decrease in the sealing performance of the stop valve 20 due to adhesion of foreign matter between the valve body 40 and the valve seat portion 42 a of the stop valve 20 .

[0019] 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 so that the suction path 22 can suck gas in a vortex shape and suppress turbulence of the airflow near the valve body 40. This makes suction easy without accumulating foreign matter.

[0020] An exhaust section 34 and an air supply section 35 are connected to the valve V. The valve V switches the connection between the suction path 30 and the exhaust section 34 and the connection between the suction path 30 and the air supply section 35. When the casting mold 12 is opened, the air supply section 35 sends air to the suction path 30, thereby blowing the suction path 24, the suction path 22, the stop valve 20 and the overflow section 18. Accordingly, the suction path 24, the suction path 22 and the stop valve 20 can be cleaned. For example, the blowing can be performed when the casting mold 12 is opened after the casting is demolded. In addition, the air supply section 35 can be omitted, and air can be supplied to the suction path 30 from the pump 34b whose action is reversed via the storage tank 34a by the exhaust section 34.

[0021] Figure 2 2 is an enlarged view showing the stop valve 20 and its vicinity. The stop valve 20 includes a valve body 40 and a receiving portion 42 for receiving the valve body 40. In addition, the valve body 40 does not have a rib 40d ( Figure 4 and Figure 5). The housing portion 42 includes a valve seat portion 42a, an upstream housing portion 42b, and a downstream housing portion 42c. The upstream housing portion 42b is arranged upstream of the valve seat portion 42a. The downstream housing portion 42c is arranged downstream of the valve seat portion 42a. The valve body 40 includes an abutment portion 40a, an upstream valve portion 40b, and a downstream valve portion 40c. The abutment portion 40a blocks the suction path 22 by abutting against the valve seat portion 42a. The upstream valve portion 40b is arranged upstream of the abutment portion 40a. The downstream valve portion 40c is arranged downstream of the abutment portion 40a.

[0022] The suction path 22, the valve body 40 (the abutment portion 40a, the upstream valve portion 40b, and the downstream valve portion 40c), and the housing portion 42 (the valve seat portion 42a, the upstream housing portion 42b, and the downstream housing portion 42c) have a common axis C0. The axis C0 forms an obtuse angle θ2 with respect to the angle reference plane S. In order to serve as a reference for the angle θ2, the angle reference plane S is set on the mating surface 12b1 having the overflow portion 18. The angle reference plane S is substantially coplanar with the mating surface 12b1 (prescribed surface). Here, the angle reference plane S is set between the position Q and the overflow portion 18. The position Q is a position where the axis C0 of the valve body 40 intersects the mating surface 12b1. The overflow portion 18 is arranged on the mating surface 12b1 (vertical plane) along the plumb line Lp, basically along the plumb line Lp. That is, the angle θ2 is substantially the angle formed by the suction path 22 and the overflow portion 18. By setting the angle θ2 to an obtuse angle, the generation of turbulence caused by a sudden change in the gas flow direction can be suppressed. As a result, the adhesion and sticking of foreign matter to the valve body 40 , the accommodating portion 42 , and the suction path 22 are suppressed.

[0023] On the other hand, setting the angle θ2 to an acute angle tends to cause turbulence of gas near the stop valve 20. This turbulence causes foreign matter to collide with the surface of the stop valve 20 or the suction path 22, and as a result, the foreign matter may adhere to or stick to the surface. The adhered or stuck foreign matter may reduce the sealing performance of the stop valve 20. The adhered or stuck foreign matter may clog the stop valve 20 or the suction path 22. In addition, the reduction in sealing performance means that the closed stop valve 20 leaks.

[0024] Figure 3 1 is a diagram showing the state of the stop valve 20 viewed from the movable mold 12a toward the fixed mold 12b. For ease of understanding, the valve body 40 is represented by a virtual line. Figure 3As shown, here, the two overflow parts 18 are arranged roughly symmetrically on the left and right. The two overflow parts 18 are respectively arranged on the matching surface 12b1 (specified surface), and have an overflow part body 18a and an introduction path 18b. The overflow part body 18a has a plurality of flow paths 18c. The plurality of flow paths 18c are connected to the mold cavity part 14 and are connected to each other at each upper part. The introduction path 18b is connected to the upper part of the overflow part body 18a and is connected to the upstream side receiving part 42b. The introduction path 18b guides the gas from the overflow part body 18a to the upstream side receiving part 42b.

[0025] The overflow portion 18 of the present embodiment, in particular, the introduction path 18b has a relatively short straight shape. Unlike the present embodiment, when the introduction path 18b is extended in a manner that makes the introduction path 18b complexly meander, the molten metal is cooled in the introduction path 18b. Accordingly, the speed of the molten metal is reduced, and as a result, the molten metal can be prevented from being ejected from the introduction path 18b. In addition, foreign matter can be captured in the introduction path 18b. However, extending the introduction path 18b in a manner that makes the introduction path 18b meander will increase the capacity of the overflow portion 18, and as a result, the amount of molten metal that is not used to make the product itself increases. In the present embodiment, since the introduction path 18b has a relatively short straight shape, the waste of molten metal is reduced. On the other hand, since the amount of foreign matter captured in the introduction path 18b is reduced, the amount of foreign matter attached to the stop valve 20 is increased. In the present embodiment, as described later, by designing the shape near the stop valve 20, the gas is swirled near the stop valve 20. The swirling of the gas suppresses the gas from stagnating in the vicinity of the stop valve, and as a result, suppresses foreign matter from being caught (ultimately attached or adhered) in the stop valve 20 .

[0026] The upstream housing portion 42b has an arc-shaped outer peripheral edge P on the mating surface 12b1 (prescribed surface). The introduction path 18b is connected to the upstream housing portion 42b at a prescribed position on the outer peripheral edge P along the tangent direction A of the outer peripheral edge P. Accordingly, the gas flowing from the introduction path 18b into the upstream housing portion 42b forms a swirl F. The swirl F is an airflow that swirls along the outer peripheral edge P. The swirl F flows toward the downstream of the housing portion 42 while swirling around the axis C0 of the valve body 40 in the housing portion 42. The gas swirling along the outer peripheral edge P flows along the surfaces of the upstream housing portion 42b and the upstream valve portion 40b. The swirling of the gas inhibits foreign matter in the gas from adhering or sticking to the vicinity of the stop valve 20. Foreign matter adhering or sticking to the vicinity of the stop valve 20 is eventually clamped in the sealing portion of the stop valve 20. The vicinity of the stop valve 20 refers to, for example, the upstream housing portion 42b and the upstream valve portion 40b.

[0027] The central axis C1 of the introduction path 18b extends along the mating surface 12b1 (vertical plane) and forms a predetermined angle θ3 with respect to the vertical line Lp. Figure 3The introduction path 18b on the left side forms a negative angle -θ3 with respect to the plumb line Lp. The introduction path 18b on the right side forms a positive angle +θ3 with respect to the plumb line Lp. Here, since the two introduction paths 18b are roughly bilaterally symmetrical, the absolute values ​​of the angles ±θ3 formed by the two introduction paths 18b with respect to the plumb line Lp are equal, but the positive and negative angles are different. The absolute values ​​of the angles ±θ3 may also be different depending on the different introduction paths 18b.

[0028] The absolute value and positive or negative of the angle ±θ3 are related to the rotational force and rotation direction of the swirl F. By making the absolute value of the angle ±θ3 greater than 0, the gas becomes easier to swirl. The positive or negative of the angle ±θ3 is related to the rotation direction. Figure 3 The gas from the left side of the inlet path 18b turns right along the outer periphery P. Figure 3 The gas in the right introduction path 18b rotates rightward along the outer periphery P. When the absolute value of the angle ±θ3 is, for example, 30° to 60°, it is possible to suppress the generation of an eddy current near the valve body 40. If an eddy current is generated near the valve body 40, foreign matter in the gas is drawn into the eddy current, and as a result, the foreign matter adheres to the valve body 40.

[0029] Here, the flow path width W0 of the introduction path 18b is smaller than the diameter R of the outer peripheral edge P (W0<R). In addition, the introduction path 18b is connected to the outer peripheral edge P in a manner that the central axis C1 of the introduction path 18b is offset from the center of the outer peripheral edge P. Accordingly, the speed of the gas flowing from the introduction path 18b into the upstream side housing portion 42b increases, and as a result, the swirling force of the gas increases. The swirling force more strongly suppresses foreign matter in the gas from being attached or adhered to the stop valve 20.

[0030] 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 connection portion where the introduction path 18b and the outer periphery P are connected to each other. The width W1 of the bottom surface 18b1 decreases as it approaches the connection portion. However, as the width W1 of the introduction path 18b decreases, the depth of the bottom surface 18b1 increases. That is, the cross-sectional area (and therefore the flow conductance) of the introduction path 18b is approximately constant. Accordingly, it is possible to maintain a rapid flow of gas.

[0031] Here, as the gas swirls, the foreign matter in the gas swirls, so that the foreign matter in the gas is subjected to centrifugal force. As a result, the heavier foreign matter in the gas (for example, powder burrs or solid release agents) may be separated from the airflow and fall into the upstream side receiving portion 42b. In most cases, the fallen foreign matter neither adheres to nor sticks to the surface of the upstream side receiving portion 42b. Therefore, most of the foreign matter that falls on the upstream side receiving portion 42b can be removed relatively easily. For example, by opening the casting mold 12 and blowing air to the casting mold 12 from the exhaust portion 34 side, the foreign matter on the upstream side receiving portion 42b can be discharged outside the casting mold 12. The upstream side receiving portion 42b is open downward (downward on the plumb line Lp). Therefore, the foreign matter on the surface of the upstream side receiving portion 42b can be removed and discharged relatively easily by blowing air.

[0032] return Figure 2 , the action of the gas after flowing from the introduction path 18b into the upstream side receiving portion 42b is described. On a plane perpendicular to the axis C0 of the upstream side receiving portion 42b, a gap Ga is defined between the upstream side receiving portion 42b and the upstream side valve portion 40b. At least when the stop valve 20 is in an open state, the cross-sectional area of ​​the gap Ga decreases as it approaches the abutment portion 40a. Therefore, the speed of the gas flowing from the introduction path 18b into the upstream side receiving portion 42b increases as it approaches the abutment portion 40a. As a result, foreign matter in the gas is less likely to adhere to the valve body 40 and the receiving portion 42 (here, the upstream side valve portion 40b, the upstream side receiving portion 42b). Here, the upstream side valve portion 40b has a truncated cone shape whose diameter increases as it approaches the abutment portion 40a. Accordingly, the cross-sectional area of ​​the gap Ga decreases as it approaches the abutment portion 40a.

[0033] In addition, a gap Gb is defined between the downstream side housing portion 42c and the downstream side valve portion 40c on a plane perpendicular to the axis C0 of the downstream side housing portion 42c. At least when the stop valve 20 is in an open state, the cross-sectional area of ​​the gap Gb increases as it approaches the drive shaft 26 within a certain interval from the abutment portion 40a. Accordingly, the occurrence of turbulence in the downstream side housing portion 42c is suppressed. As a result, the swirl F of the gas can be maintained, thereby suppressing the gas from being retained in the valve body 40 and the housing portion 42 (here, the downstream side valve portion 40c and the downstream side housing portion 42c). Therefore, the separation and attachment of foreign matter caused by the decrease in the flow rate of the gas is suppressed, and as a result, foreign matter is prevented from being caught in the stop valve 20. Here, the outer diameter of the downstream side valve portion 40c has a truncated cone shape that becomes smaller as it approaches the drive shaft 26. Accordingly, the cross-sectional area of ​​the gap Gb increases as it approaches the downstream side of the abutment portion 40a.

[0034] In this way, the gas flowing from the introduction path 18b into the upstream receiving portion 42b forms a swirl F. The swirl F rotates along the outer peripheral edge P of the upstream receiving portion 42b. The swirl F flows from the upstream receiving portion 42b into the downstream receiving portion 42c. Here, in the downstream receiving portion 42c involved in this embodiment, the valve body 40 may not have, for example, Figure 4 However, in order to maintain and strengthen the swirl flow F, it is more preferable that the valve body 40 has the rib 40d.

[0035] Figure 4 This is a diagram showing an example of an enlarged view of a valve body 40 of a stop valve 20 according to a modified example. Figure 5 is a graph showing the valve body 40 viewed from the downstream direction along the axis C0. Figure 4 The valve body 40 has a rib 40d extending along the flow direction of the swirl flow F on the downstream valve portion 40c. The valve body 40 may not have the rib 40d. As described above, this embodiment corresponds to the case where the rib 40d is not provided. Figure 4 and Figure 5 As shown in FIG. 1 , the rib 40d extends along the line L1 (extension line). The line L1 forms an angle θ4 with respect to the reference line L0. The reference line L0 is set in a manner that extends from the axis C0 along the surface of the downstream valve portion 40c. That is, the rib 40d is inclined radially outward of the valve body 40 along the swirl direction of the swirl F (inclined relative to the radial direction). Therefore, the radial outer end 40do of the rib 40d is located downstream of the swirl F in the circumferential direction of the valve body 40 relative to the radial inner end 40d i of the rib 40d. Furthermore, the rib 40d is inclined radially outward along the swirl direction of the swirl F. Figure 4 The rib 40d is inclined in the direction of the arrow X (inclined relative to the axial direction). The arrow X direction is the direction along the axial direction of the drive shaft 26 side of the valve body 40 and toward the downstream side. Therefore, the root 40dr of the rib 40d is located on the upstream side of the swirl F in the circumferential direction of the valve body 40 relative to the top 40dt of the rib 40d (the protruding end protruding from the downstream side valve portion 40c).

[0036] Here, when the valve body 40 is observed from the downstream direction, the angle θ4 is set to the negative direction (rotating to the right). Accordingly, the swirl F rotating to the right when the valve body 40 is observed from the downstream direction can be maintained. That is, the positive and negative angles θ3 formed by the introduction path 18b relative to the upstream side receiving portion 42b correspond to the positive and negative angles θ4 formed by the extension direction of the rib 40d relative to the reference line L0. Accordingly, the swirl F generated in the upstream side receiving portion 42b can be maintained. Moreover, the rib 40d is inclined in the axial direction (X direction) along the swirling direction of the swirl F, thereby making it easier to maintain the swirl F.

[0037] Here, three ribs 40d are arranged along the outer peripheral surface of the downstream valve portion 40c. However, the number of ribs 40d may be set to an appropriate number of two or more. In this way, the valve body 40 has ribs, which makes it easy to maintain the swirl flow F of the gas in the downstream receiving portion 42c.

[0038] As described above, in the present embodiment, the gas swirls in the vicinity of the stop valve 20. Therefore, foreign matter in the gas sucked out from the cavity portion 14 basically passes through the suction path 22, and neither adheres to nor sticks to the stop valve 20. Finally, the foreign matter in the gas is captured by the filter 36. As a result, the exhaust device 10 can maintain a good state for a long time. As described above, the centrifugal force generated by the swirl of the gas can cause the heavier foreign matter in the gas to fall into the upstream side receiving portion 42b. However, the foreign matter neither adheres to nor sticks to the upstream side receiving portion 42b. Therefore, the foreign matter can be easily removed by blowing from the exhaust portion 34. In addition, the present invention is not limited to the above-mentioned embodiment, and various structures can be adopted without departing from the main purpose of the present invention.

[0039] [Technical solution obtained from implementation method]

[0040] The following describes technical solutions that can be grasped from the above-mentioned embodiments.

[0041] [1] A vacuum device (10) for a casting mold (12), comprising an overflow portion (18), a suction path (22) and a stop valve (20), wherein the overflow portion is connected to a cavity portion (14) of the casting mold and is formed along a specified surface (matching surface 12b1); the suction path is used to suck gas in the cavity portion via the overflow portion; the stop valve is connected between the overflow portion and the suction path and is capable of blocking the suction path, the stop valve comprising a valve body (40) and a receiving portion (42) for receiving the valve body, the receiving portion comprising a valve seat portion (42a), an upstream receiving portion (42b) on the upstream side of the valve seat portion, and a downstream receiving portion (42c) on the downstream side of the valve seat portion, the valve body having a stop valve portion (40) and a stop valve portion (40) for receiving the valve body. A contact portion (40a), an upstream valve portion (40b) and a downstream valve portion (40c), wherein the contact portion contacts the valve seat portion to block the suction path; the upstream valve portion is on the upstream side of the contact portion; the downstream valve portion is on the downstream side of the contact portion; the prescribed surface has an angle reference surface (S) between the overflow portion and the position where the axis (C0) of the valve body intersects the prescribed surface; the angle (θ2) formed by the axis (C0) of the downstream receiving portion and the angle reference surface is an obtuse angle; the upstream receiving portion has an arc-shaped outer peripheral edge (P) on the prescribed surface; the overflow portion has an introduction path (18b) connected to the upstream receiving portion and used to guide the gas to the upstream receiving portion. The introduction path is connected to the upstream receiving portion at a prescribed position on the outer peripheral edge along the tangent direction (A) of the outer peripheral edge. Accordingly, since the introduction path of the overflow portion is connected to the upstream side housing portion of the housing portion that accommodates the valve body and the arc-shaped outer peripheral edge of the upstream side housing portion along the tangent direction of the outer peripheral edge, the gas flowing from the introduction path into the upstream side housing portion forms a swirl that swirls along the outer peripheral edge. As a result, it is possible to prevent foreign matter in the gas from colliding with the stop valve 20 and the like and attaching or sticking to it. In addition, by setting the angle formed by the axis of the downstream side housing portion and the specified surface (angle reference surface) where the overflow portion is formed to an obtuse angle, it is possible to prevent the occurrence of turbulence caused by a sudden change in the gas flow direction, thereby further preventing foreign matter from attaching or sticking to the stop valve and the like.

[0042] [2] The flow path width (W1) of the introduction path is smaller than the diameter (R) of the outer periphery, and the introduction path is connected to the outer periphery in a manner that the central axis (C1) of the introduction path deviates from the center of the outer periphery. Accordingly, the swirling force of the gas flowing from the introduction path can be increased, thereby more effectively suppressing the adhesion of foreign matter in the gas to the stop valve, etc.

[0043] [3] The predetermined plane is along the vertical line (Lp), and the central axis of the introduction path is along the predetermined plane and forms a predetermined angle (θ3) with respect to the vertical line. Thus, the rotational force and the rotational direction of the swirl flow can be set.

[0044] [4] The introduction path has a planar bottom surface (18b1) extending along the central axis of the introduction path, and the width of the bottom surface decreases as it approaches the specified position. Accordingly, the speed of the gas flowing from the introduction path into the upstream receiving portion can be increased, thereby increasing the swirl force, preventing the gas from being retained near the valve body, and more effectively preventing foreign matter in the gas from being attached and being caught in the stop valve, etc.

[0045] [5] At least when the stop valve is in an open state, the cross-sectional area of ​​the gap (Gb) between the downstream side receiving portion and the downstream side valve portion on a plane perpendicular to the axis (C0) of the downstream side receiving portion increases as it moves from the abutment portion toward the downstream side within a certain interval from the abutment portion. Therefore, it is possible to suppress the generation of turbulence in the downstream side receiving portion, thereby suppressing the adhesion and sticking of foreign matter in the gas to the stop valve.

[0046] [6] The downstream valve portion is in the shape of a truncated cone whose diameter decreases as it moves from the abutment portion toward the downstream side. Thus, the cross-sectional area of ​​the gap between the downstream accommodating portion and the downstream valve portion can be increased as it moves away from the abutment portion within a certain interval from the abutment portion.

[0047] [7] The gas flowing from the introduction path into the downstream receiving portion forms a swirl flow rotating along the outer periphery, and the downstream valve portion has a rib (40d) extending along the rotation direction of the swirl flow. By adding the rib, the swirl flow of the gas can be further maintained and strengthened.

Claims

1. A vacuum device for a casting mold, characterized in that: It has an overflow portion (18), a suction path (22) and a stop valve (20), wherein: The overflow portion is connected to the cavity portion (14) of the casting mold (12) and is formed along a predetermined surface (12b1); The suction path is used to suck the gas in the mold cavity portion through the overflow portion; The shutoff valve is connected between the overflow portion and the suction path and is capable of blocking the suction path. The stop valve comprises a valve body (40) and a receiving portion (42) for receiving the valve body. The housing portion includes a valve seat portion (42a), an upstream housing portion (42b) located upstream of the valve seat portion, and a downstream housing portion (42c) located downstream of the valve seat portion. The valve body comprises an abutment portion (40a), an upstream valve portion (40b) and a downstream valve portion (40c), wherein the abutment portion abuts against the valve seat portion to block the suction path; the upstream valve portion is closer to the upstream side than the abutment portion; and the downstream valve portion is closer to the downstream side than the abutment portion. The predetermined surface has an angle reference surface (S) between the overflow portion and the position where the axis (C0) of the valve body intersects the predetermined surface. The angle (θ2) formed by the axis (C0) of the downstream side receiving portion and the angle reference plane is an obtuse angle, The upstream side receiving portion has an arc-shaped outer peripheral edge (P) on the predetermined surface, The overflow portion has an introduction path (18b) connected to the upstream side receiving portion and used to guide the gas to the upstream side receiving portion. The introduction path is connected to the upstream accommodation portion at a predetermined position on the outer peripheral edge along a tangential direction (A) of the outer peripheral edge.

2. The exhaust device for a casting mold according to claim 1, characterized in that: The flow path width (W1) of the introduction path is smaller than the diameter (R) of the outer peripheral edge, The introduction path is connected to the outer periphery in such a manner that a central axis (C1) of the introduction path is offset from a center of the outer periphery.

3. The exhaust device for a casting mold according to claim 1 or 2, characterized in that: The prescribed surface is along the plumb line (Lp), The central axis of the introduction path is along the predetermined plane and forms a predetermined angle (θ3) with respect to the vertical line.

4. The exhaust device for a casting mold according to claim 1 or 2, characterized in that: The introduction path has a planar bottom surface (18b1) extending along the central axis of the introduction path, The width of the bottom surface decreases toward the predetermined portion.

5. The exhaust device for a casting mold according to claim 1 or 2, characterized in that: At least when the stop valve is in an open state, the cross-sectional area of ​​the 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 within a certain interval from the abutment portion as it moves from the abutment portion toward the downstream side.

6. The exhaust device for a casting mold according to claim 5, characterized in that: The downstream valve portion has a truncated cone shape whose diameter decreases as it moves from the contact portion toward the downstream side.

7. The exhaust device for a casting mold according to claim 1 or 2, characterized in that: The gas flowing from the introduction path into the downstream side storage portion forms a swirl flow rotating along the outer peripheral edge. The downstream valve portion has a rib (40d) extending along the rotation direction of the swirl flow.

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