Degassing mechanism of a tilting gravity casting apparatus

Abstract

In tilting gravity casting, product quality is improved by efficiently discharging gas from inside the mold to the outside. [Solution] A degassing mechanism in a tilting gravity casting apparatus in which molten metal M is stored in a ladle 7 of a mold 2 and the mold 2 is tilted to pour the molten metal M into the cavity 6 of the mold 2 via a runner 5, wherein a degassing pin 70 is removably mounted in a pin mounting hole 71 of the mold 2 so that its tip surface faces the cavity 6, and multiple vent grooves 80 are formed on the outer peripheral surface 70a of the tip of the degassing pin 70 at intervals in the circumferential direction, extending to the tip surface 70a of the degassing pin 70, and between adjacent vent grooves 80 there are fitting surfaces 81 that fit into surface contact with the wall surface of the pin mounting hole 71, and an air vent 74 for degassing gas from the cavity 6 is formed by the vent grooves 80 and the wall surface of the pin mounting hole 71, and the vent grooves 80 are arc-shaped in cross-section.

Description

Technical Field

[0001] The present invention relates to a gas venting mechanism of a tilting gravity casting device.

Background Art

[0002] For example, as described in Patent Document 1 below, there is a tilting gravity casting device that has a ladle in a mold, stores molten metal in this ladle, and pours the molten metal into the cavity of the mold through a runner when the mold is tilted. In such a tilting gravity casting device, it is important to efficiently discharge the gas remaining in the mold to the outside in order to ensure the quality of the product. Therefore, further improvement of the gas venting structure is required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to improve product quality by efficiently discharging the gas in the mold to the outside in tilting gravity casting.

Means for Solving the Problems

[0005] The degassing mechanism for a tilting gravity casting apparatus according to the present invention is a degassing mechanism for a tilting gravity casting apparatus in which molten metal is stored in the ladle of the mold and poured into the cavity of the mold via a runner by tilting the mold. A degassing pin is removably mounted in the pin mounting hole of the mold so that its tip surface faces the cavity. Multiple vent grooves are formed on the outer circumferential surface of the tip of the degassing pin, extending to the tip surface of the degassing pin at circumferential intervals. Between adjacent vent grooves, fitting surfaces are formed that make surface contact with the wall surface of the pin mounting hole. The vent grooves and the wall surface of the pin mounting hole form an air vent for degassing gas from the cavity, and the vent grooves are arc-shaped in cross-section. Note that "arc-shaped in cross-section" refers to the cross-sectional view when the vent groove is crossed in the width direction, and means that the bottom surface of the vent groove is arc-shaped in that cross-sectional view.

[0006] In this configuration, a gas vent pin is installed in the pin mounting hole of the mold. A vent groove is formed on the outer circumference of the tip of the gas vent pin, and this vent groove forms an air vent. The air vent opens into the cavity forming wall of the mold. The cavity forming wall is the wall surface of the mold that defines the cavity. The air vent communicates with the cavity through the opening in the cavity forming wall, and the cavity communicates with the outside of the mold via the air vent. Therefore, gas in the cavity is discharged to the outside of the mold via the air vent. In addition, since the gas vent pin is installed in a removable manner, maintenance such as cleaning the air vent can be performed by periodically removing the gas vent pin from the mold. For example, clogging of the air vent can be resolved by removing burrs of molten metal adhering to the vent groove.

[0007] Furthermore, because the vent groove is formed in an arc shape in cross-section, the opening area of ​​the air vent can be easily secured without excessively increasing the circumferential dimensions (width) of the vent groove. When the vent groove is arc-shaped in cross-section, the bottom surface of the vent groove is a concave curved surface rather than a flat surface. On the other hand, when the vent groove is straight in cross-section, the bottom surface of the vent groove is flat. When the vent groove is straight in cross-section, that is, when it has a D-cut shape, it is not easy to secure the depth of the vent groove, and in order to secure the depth of the vent groove, it is necessary to increase the circumferential dimensions of the vent groove. Therefore, it is not easy to secure the opening area. In contrast, when the vent groove is formed in an arc shape in cross-section, the depth of the vent groove can be easily increased without excessively increasing the circumferential dimensions of the vent groove, and the opening area can be easily secured. Furthermore, because the opening area at both ends of the air vent in the circumferential direction can be increased, it is possible to reduce the likelihood of burr clogging, which tends to occur at both ends of the air vent in the circumferential direction, and even if burr clogging does occur, the burrs can be easily removed during maintenance.

[0008] Furthermore, on the outer circumferential surface of the tip of the gas vent pin, fitting surfaces are formed between adjacent vent grooves in the circumferential direction, so as to fit into surface contact with the wall surface of the pin mounting hole. As a result, the fitting surface of the gas vent pin can be brought into close contact with the wall surface of the pin mounting hole, resulting in a gap-free fit between the gas vent pin and the wall surface of the pin mounting hole. Moreover, since the vent grooves are arc-shaped in cross-section, it is not necessary to excessively enlarge the circumferential dimensions of the vent grooves, thus allowing for a large circumferential dimension of the fitting surface. As a result, the gas vent pin can be securely fitted into the pin mounting hole without any gaps.

[0009] In particular, the gas vent pin comprises a cylindrical outer pin with a vent groove and a fitting surface formed on the outer circumferential surface of its tip, and an inner pin mounted radially inward of the outer pin. Multiple internal vent grooves extending to the tip surface of the gas vent pin are formed on the outer circumferential surface of the tip of the inner pin at circumferential intervals, and between adjacent internal vent grooves, internal fitting surfaces are formed that engage in surface contact with the inner circumferential surface of the outer pin. The internal vent grooves and the inner circumferential surface of the outer pin form an internal air vent for venting gas from the cavity, and preferably the internal vent grooves are arc-shaped in cross-section. With this configuration, the gas vent pin has a multilayer structure comprising an outer pin and an inner pin. Gas can be efficiently discharged to the outside through the air vent between the pin mounting hole and the outer pin, and the internal air vent between the outer pin and the inner pin.

[0010] Furthermore, it is preferable that an outer small-diameter portion, smaller in diameter than the outer circumferential surface of the tip of the outer pin, is formed on the base end side of the outer circumferential surface of the tip of the outer pin, so that gas is discharged to the outside through the outer annular gap between the outer small-diameter portion and the wall surface of the pin mounting hole from the air vent. With this configuration, the gas passing through the multiple air vents is collected in the outer annular gap before being discharged to the outside. Therefore, gas can be discharged efficiently. In addition, by providing the outer small-diameter portion, the axial length of the vent groove can be shortened, making it easier to machine the vent groove.

[0011] Furthermore, it is preferable that an inner small-diameter portion, smaller in diameter than the outer circumferential surface of the tip of the inner pin, is formed on the base end side of the outer circumferential surface of the tip of the inner pin, and that a lateral hole is formed in the inner small-diameter portion, as well as an axial hole that communicates with the lateral hole and extends axially toward the base end of the inner pin, so that gas is discharged to the outside from the inner air vent through the inner annular gap between the outer circumferential surface of the inner small-diameter portion and the inner circumferential surface of the outer pin, the lateral hole, and the axial hole. With this configuration, the gas passing through the multiple inner air vents is collected in the inner annular gap and then discharged to the outside through the lateral hole and the axial hole. Therefore, gas can be discharged efficiently.

[0012] Furthermore, the mold comprises an upper mold located on the upper side before tilting and a lower mold located on the lower side before tilting, and it is preferable that the gas venting pin is provided on the upper mold. With this configuration, gas that tends to accumulate on the upper mold side of the cavity can be efficiently discharged.

[0013] In particular, it is preferable that the upper mold is provided with a shutter that blocks the runner, and that the gas vent pin extends in the direction from the cavity toward the shutter. With this configuration, in the tilted state, the runner and shutter are located above the cavity, and the gas vent pin also extends upward from the cavity. Therefore, gas that tends to accumulate at the top of the cavity in the tilted state can be efficiently discharged upward from the upper mold by the gas vent pin.

[0014] Furthermore, the mold is provided with a pressure pin that presses the molten metal in the cavity in the clamping direction, and the casting has a main body formed at the location pressed by the pressure pin and an arm extending radially outward from the main body, and it is preferable that the gas venting pin is positioned at the location that forms the tip of the arm. With this configuration, the gas venting pin is positioned at the location that forms the tip of the arm, which is a place where the pressing force of the pressure pin does not easily reach and gas tends to accumulate, so gas can be effectively discharged and the quality of the tip of the arm can be improved.

[0015] In particular, the casting is a steering knuckle for a vehicle, the main body is a bearing support that rotatably supports the wheel hub, and the arm is a tie rod arm having a tie rod connecting portion at its tip to which a tie rod is connected. Preferably, the pressure pin is positioned at the location that forms the bearing support portion, and the gas vent pin is positioned at the location that forms the tie rod connecting portion. With this configuration, the quality of the tie rod connecting portion in the steering knuckle, which is an important safety component, can be improved. [Effects of the Invention]

[0016] As described above, the gas vent pin is removably attached to the mold, and a vent groove and a fitting surface having an arcuate cross-section are formed on the outer peripheral surface of the tip of the gas vent pin. Therefore, the gas in the cavity can be efficiently discharged to the outside, improving the quality of the product. In addition, the air vent is less likely to be clogged with molten metal burrs, improving the maintainability.

Brief Description of the Drawings

[0017] [Figure 1] Schematic perspective view for explaining a steering knuckle for a vehicle manufactured by a tilting gravity casting apparatus according to an embodiment of the present invention. [Figure 2] Front view of the same steering knuckle. [Figure 3] Perspective view of the same steering knuckle. [Figure 4] Cross-sectional view of the same tilting gravity casting apparatus. [Figure 5] Cross-sectional view showing a state where the mold is tilted 15 degrees in the tilting process of the same apparatus. [Figure 6] Cross-sectional view showing a state where the mold is tilted 45 degrees in the tilting process of the same apparatus. [Figure 7] Cross-sectional view showing a state where the molten metal in the cavity is pressurized by a pressure pin after the runner is blocked by a shutter. [Figure 8] Cross-sectional view showing a state where the tilting process of the same apparatus is completed. [Figure 9] Cross-sectional view showing a state where the molten metal in the runner is pressurized by an auxiliary pressure pin after the tilting process of the same apparatus is completed. [Figure 10] Schematic view of the upper mold of the same apparatus as seen from the lower mold side. [Figure 11] Cross-sectional view showing the periphery of the gas vent pin in the mold of the same apparatus. [Figure 12] Cross-sectional view showing the periphery of the gas vent pin in the mold of the same apparatus. [Figure 13] View of the periphery of the gas vent pin in the mold of the same apparatus as seen from the cavity side. [Figure 14] Showing the main part of the same gas vent pin, (a) is a front view, and (b) is a cross-sectional view. [Figure 15] The main parts of the outer pin of the gas vent pin are shown, with (a) being a front view and (b) being a cross-sectional view. [Figure 16] The main parts of the inner pin of the gas vent pin are shown, with (a) being a front view and (b) being a cross-sectional view. [Modes for carrying out the invention]

[0018] The following describes a tilting gravity casting apparatus (hereinafter simply referred to as casting apparatus 1) according to one embodiment of the present invention, but first, an overview of a general vehicle suspension system 100 will be described. Figure 1 shows an overview of a general suspension system 100. Figure 1 is a view of the suspension system 100 from inside the vehicle. The suspension system 100 is for the front wheels and is of the MacPherson strut type. The suspension system 100 includes a steering knuckle (hereinafter simply referred to as knuckle 101), which is a support member that rotatably supports a wheel hub (not shown), a disc rotor 103 that rotates integrally with the wheel 102, and a brake caliper 104.

[0019] The knuckle 101 is a casting (product) cast by the casting apparatus 1 shown in Figure 4, etc., and is manufactured by machining predetermined parts after casting. The knuckle 101 in this embodiment is shown in Figures 2 and 3. The knuckle 101 has a bearing support portion 110, a damper connecting portion 111, a lower arm connecting portion 112, a tie rod connecting portion 113, and a caliper connecting portion 114. The bearing support portion 110 is provided in the center of the knuckle 101. The bearing support portion 110 rotatably supports the wheel hub. The axial direction of the bearing support portion 110 is the direction of the center line of the wheel 102, and the radial direction of the bearing support portion 110 is the radial direction of the wheel 102. The bearing support portion 110 has a main hole 120 that penetrates in the axial direction of the bearing support portion 110. The main hole 120 is formed by post-processing (machining) after casting. The main hole 120 is aligned in the left-right direction of the vehicle. A hub bearing (not shown) is positioned in the main hole 120. Multiple first connecting holes 121 are formed around the main hole 120; in this embodiment, four first connecting holes 121 are formed. The first connecting holes 121 are through holes that penetrate the main hole 120 along its axial direction. Hub bolts (not shown) are screwed into the first connecting holes 121. The first connecting holes 121 are formed by post-processing.

[0020] The damper connecting portion 111 is located radially outward and above the bearing support portion 110. The damper connecting portion 111 is provided with a second connecting hole 122. A pair of second connecting holes 122 are provided, spaced apart in the vertical direction of the vehicle. The second connecting hole 122 is a through hole that penetrates in the left-right direction of the paper in Figure 2, i.e., along the front-rear direction of the vehicle. The second connecting hole 122 is formed by post-processing. The damper 105 is connected to the damper connecting portion 111 through the second connecting hole 122.

[0021] The lower arm connecting portion 112 is located radially outward and below the bearing support portion 110. The lower arm connecting portion 112 is located on the opposite side of the main hole 120 from the damper connecting portion 111. The lower arm connecting portion 112 is provided with a third connecting hole 123. The third connecting hole 123 is a through hole that extends vertically. The third connecting hole 123 is formed by post-processing. The lower arm 106 is connected to the lower arm connecting portion 112 through the third connecting hole 123.

[0022] The knuckle 101 has a tie rod arm 115. The tie rod arm 115 extends radially outward from the bearing support portion 110 and toward the rear of the vehicle. The tie rod arm 115 extends from the bearing support portion 110 in the left-right direction in Figure 2 and in a direction perpendicular to the damper connecting portion 111. The tie rod connecting portion 113 is provided at the tip of the tie rod arm 115. The tie rod connecting portion 113 is provided with a fourth connecting hole 124. The fourth connecting hole 124 is a through hole that penetrates in the vertical direction. The fourth connecting hole 124 is formed by post-processing. The tie rod 107 is connected to the tie rod connecting portion 113 through the fourth connecting hole 124.

[0023] The caliper connecting portion 114 is located radially outward from the bearing support portion 110 and towards the front of the vehicle. The caliper connecting portion 114 is located on the opposite side of the tie rod connecting portion 113 from the main hole 120. The caliper connecting portion 114 is provided with a fifth connecting hole 125. The fifth connecting hole 125 is provided in pairs, spaced apart vertically. The fifth connecting hole 125 is a through hole that penetrates the main hole 120 along its axial direction. The brake caliper 104 is connected to the caliper connecting portion 114 through the fifth connecting hole 125.

[0024] Next, the casting apparatus 1 of this embodiment will be described. First, the overall configuration of the casting apparatus 1 will be described with reference to Figures 4 to 9. Figure 4 shows the horizontal state before tilting. In the following description, the vertical direction will be based on the horizontal state. The casting apparatus 1 is equipped with a mold 2, which is equipped with a lower mold 3 located on the lower side in the horizontal state before tilting, and an upper mold 4 located on the upper side in the horizontal state. The lower mold 3 and the upper mold 4 define the runner 5 and the cavity 6. The runner-forming wall surface of the mold 2 that forms the runner 5 is formed by dividing it vertically by the lower mold 3 and the upper mold 4. Similarly, the cavity-forming wall surface 61 that forms the cavity 6 is formed by dividing it vertically by the lower mold 3 and the upper mold 4. A ladle 7 is fixed to the lower mold 3. Molten metal M such as aluminum alloy is supplied to and stored in the ladle 7. In this embodiment, the upper mold 4 is a movable mold and the lower mold 3 is a fixed mold, but the reverse may also be true.

[0025] The lower mold 3 is fixed to the upper surface of the base 8. The lower end of the guide shaft 9 is fixed to the base 8, and the upper end of the guide shaft 9 is fixed to the top plate 10. A first hydraulic cylinder 11 is fixed to the upper surface of the top plate 10, and the tip of the first cylinder rod 12, which passes through the top plate 10, is connected to a movable plate 13 disposed below the top plate 10. When the first hydraulic cylinder 11 is driven, the movable plate 13 is guided by the guide shaft 9 and moves vertically between the base 8 and the top plate 10 in Figure 1. A connecting member 14 is provided on the lower side of the movable plate 13, and the movable plate 13 and the upper mold 4 are connected by this connecting member 14. Therefore, the upper mold 4 moves vertically together with the movable plate 13.

[0026] The casting apparatus 1 is equipped with a tilting mechanism (not shown) for tilting the mold 2. The tilting mechanism causes the mold 2 to tilt (rotate) approximately 90 degrees in the forward direction indicated by the symbol α from the horizontal state shown in Figure 4 to the vertical state shown in Figure 8, and then rotate approximately 90 degrees in the reverse direction indicated by the symbol β from that vertical state back to the horizontal state shown in Figure 4. The casting apparatus 1 performs a reciprocating rotational operation between these horizontal and vertical states.

[0027] A second hydraulic cylinder 15 is fixed to the upper surface of the upper mold 4. The second cylinder rod 16 of the second hydraulic cylinder 15 is connected to a shutter 18. The shutter 18 is driven by the second cylinder rod 16 to open and close the runner 5. The shutter 18 is positioned relatively close to the exit of the runner 5. Driven by the second hydraulic cylinder 15, the shutter 18 moves downward, that is, toward the lower mold 3, to close the runner 5.

[0028] A third hydraulic cylinder 20 for pressurization is fixed to the underside of the base 8. The third cylinder rod 21 of the third hydraulic cylinder 20 is connected to a pressure pin 23. The pressure pin 23 is located in the center of the cavity 6. The pressure pin 23 penetrates the base 8, enters the lower mold 3, and reaches the cavity 6. When the third hydraulic cylinder 20 is driven, the tip of the pressure pin 23 enters the cavity 6 and pressurizes the molten metal M in the cavity 6 upwards, i.e., towards the upper mold 4. In other words, the pressure pin 23 pressurizes the molten metal M in the clamping direction.

[0029] A fourth hydraulic cylinder 50 for auxiliary pressurization is fixed to the underside of the base 8. The fourth cylinder rod 51 of the fourth hydraulic cylinder 50 is connected to an auxiliary pressurization pin 53. The auxiliary pressurization pin 53 penetrates the base 8. When the fourth hydraulic cylinder 50 is driven, the tip of the auxiliary pressurization pin 53 enters the runner 5 and pressurizes the molten metal M in the runner 5 upwards, i.e., towards the upper mold 4. Thus, the protruding direction of the auxiliary pressurization pin 53 and the protruding direction of the shutter 18 are opposite to each other. The auxiliary pressurization pin 53 is positioned near the exit of the runner 5, as shown in Figure 4. The auxiliary pressurization pin 53 is located between the shutter 18 and the cavity 6.

[0030] The tilting process will now be explained. Figure 5 shows the mold 2 tilted 15 degrees from the horizontal state shown in Figure 1, Figures 6 and 7 show the mold 2 tilted 45 degrees, and Figures 8 and 9 show the vertical state after the tilting operation is completed. First, in the horizontal state shown in Figure 4, molten metal M is accumulated in the ladle 7. The shutter 18 is in the open position, and the pressure pin 23 and auxiliary pressure pin 53 are in the retracted position.

[0031] Next, the casting apparatus 1 is tilted from the horizontal position shown in Figure 4 in the direction of symbol α (forward direction). As the casting apparatus 1 is tilted, the molten metal M in the ladle 7 is poured into the cavity 6 through the runner 5. As shown in Figure 6, when the casting apparatus 1 is tilted at a 45-degree angle, the shutter 18 closes and blocks the runner 5. Then, as shown in Figure 7, with the shutter 18 still closed, the pressure pin 23 protrudes and pressurizes the molten metal M in the cavity 6. Then, with the shutter 18 still closed and the pressure pin 23 still protruding, the casting apparatus 1 rotates further in the forward direction to a vertical position as shown in Figure 8. Then, in the vertical position, as shown in Figure 9, the auxiliary pressure pin 53 protrudes and pressurizes the molten metal M near the outlet of the runner 5.

[0032] After the molten metal M in cavity 6 has solidified, the mold opening process is performed. The molten metal M in cavity 6 solidifies most slowly near the pressure pin 23 and faster near the runner 5. Therefore, the auxiliary pressure pin 53 is first retracted from inside the runner 5, and then the pressure pin 23 is retracted from cavity 6. Then, the first hydraulic cylinder 11 is driven to move the upper mold 4 together with the movable plate 13 to the right in Figure 9, separating the upper mold 4 from the lower mold 3. Figure 10 is a view of the upper mold 4 in the open state, seen from the lower mold 3 side. Then, the cast product, the knuckle 101, is removed from the upper mold 4 using an ejector pin (not shown). After removing the knuckle 101, a release agent is applied to the runner forming wall and the cavity forming wall 61. Then, the first hydraulic cylinder 11 is driven to move the upper mold 4 together with the movable plate 13 to the left in Figure 9, performing a mold clamping process in which the upper mold 4 contacts the lower mold 3. After clamping, the casting apparatus 1 is rotated in the reverse direction β to return it to the horizontal position shown in Figure 4.

[0033] The knuckle 101 described above is cast using such a casting apparatus 1. The knuckle 101 in its cast state is a semi-finished product. The knuckle 101 shown in Figure 10 is a semi-finished product. The semi-finished knuckle 101 is removed from the upper mold 4 and then further processed to become the final product. The knuckle 101 shown in Figures 2 and 3 has a first surface 101a that faces inward when mounted on a vehicle, and a second surface 101b that is opposite to the first surface 101a and faces outward when mounted on a vehicle. Figures 2 and 3 are views of the knuckle 101 from the first surface 101a side. The runner 5 and shutter 18 are shown in Figures 2 and 3 by dashed lines.

[0034] The knuckle 101 is cast such that the axial direction of the main hole 120 is the direction of the mold opening and closing. The first surface 101a of the knuckle 101 is formed by the upper mold 4, and the second surface 101b of the knuckle 101 is formed by the lower mold 3. Furthermore, the knuckle 101 is cast such that the upper part of the knuckle 101 on the vehicle is on the lower side of the mold 2 in the vertical state, i.e., the cavity 6 side relative to the shutter 18, and the lower part of the knuckle 101 on the vehicle is on the upper side of the mold 2 in the vertical state, i.e., the shutter 18 side relative to the cavity 6. Therefore, the bearing support portion 110 of the knuckle 101 is formed in the central part of the cavity 6, the damper connecting portion 111 is formed in the part of the cavity 6 furthest from the runner 5, and the lower arm connecting portion 112 is formed in the part of the cavity 6 closest to the runner 5. Furthermore, the location where the tie rod connection portion 113 is formed is the part of the cavity 6 furthest to the side from the center. Figure 11 shows a cross-section of the cavity 6 where the tie rod connection portion 113 is formed. The tie rod connection portion 113 is mostly formed by the upper mold 4.

[0035] As shown in Figures 4 to 9, the upper mold 4 has a cylindrical projection 60 that protrudes toward the lower mold 3. The cylindrical projection 60 is located in the center of the cavity 6 and protrudes into the cavity 6. The cylindrical projection 60 is coaxial with the main hole 120 of the knuckle 101, and this cylindrical projection 60 forms a first circular recess (not shown) on the first surface 101a of the knuckle 101 after casting. The pressure pin 23 described above is coaxially positioned opposite the cylindrical projection 60 and presses on the area that will become the second surface 101b of the knuckle 101. As shown in Figure 7, the pressure pin 23 enters the cavity 6, so a second circular recess 62 is formed on the second surface 101b of the knuckle 101 after casting, at a position coaxial with the first circular recess and opposite to it (see Figure 10). In post-casting processing, the main hole 120 is formed by penetrating the space between the bottom surface of the first circular recess and the bottom surface of the second circular recess 62.

[0036] A gas venting pin 70 is provided in the upper mold 4. A pin mounting hole 71 is formed in the upper mold 4. The pin mounting hole 71 opens into the cavity forming wall surface 61 of the upper mold 4 and also opens into the end face of the upper mold 4 on the shutter 18 side. The pin mounting hole 71 has a circular cross-section and is formed in a straight line from the end face of the upper mold 4 on the shutter 18 side to the cavity 6. The gas venting pin 70 is inserted into the pin mounting hole 71. The gas venting pin 70 is removable from the mold 2. Therefore, during maintenance of the mold 2, the gas venting pin 70 is removed from the pin mounting hole 71. The gas venting pin 70 is inserted into and removed from the opening on the shutter 18 side of the upper mold 4.

[0037] As shown in Figures 2, 3, 10, and 11, the gas vent pin 70 is positioned facing the portion of the cavity 6 that forms the tie rod connecting portion 113. The tip surface 70a of the gas vent pin 70 constitutes part of the cavity forming wall surface 61 and faces the portion that forms the lower surface of the tie rod connecting portion 113. The gas vent pin 70 is aligned with the vehicle's vertical direction along the tie rod connecting portion 113. The gas vent pin 70 is positioned coaxially with the fourth connecting hole 124 of the tie rod connecting portion 113, which is formed by post-processing.

[0038] Figures 12 and 13 show the vicinity of the tip of the vent pin 70 in the mold 2. Figure 12 is a cross-sectional view, and Figure 13 is a view of the tip surface 70a of the vent pin 70 as seen from the cavity 6 side. Figure 14 shows details of the vent pin 70. In this embodiment, the vent pin 70 has a two-layer structure. That is, the vent pin 70 comprises an outer pin 72 and an inner pin 73. The inner pin 73 is mounted coaxially inside the outer pin 72. Figure 15 shows the outer pin 72, and Figure 16 shows the inner pin 73.

[0039] The outer circumferential surface of the outer pin 72 constitutes the outer circumferential surface of the gas vent pin 70. As shown in Figures 13 and 15, numerous vent grooves 80 are formed on the outer circumferential surface 82 of the tip of the outer pin 72 at regular intervals in the circumferential direction. The vent grooves 80 are arc-shaped in cross-section. The bottom surface of the vent grooves 80 is not a flat surface, but a concave curved surface that curves toward the center of the outer pin 72. The vent grooves 80 extend linearly along the axial direction of the outer pin 72. As a result of the formation of numerous vent grooves 80 on the outer circumferential surface 82 of the tip of the outer pin 72, numerous air vents 74 are formed between the outer circumferential surface 82 of the tip of the outer pin 72 and the wall surface of the pin mounting hole 71. In this embodiment, 15 air vents 74 are formed, but the number is arbitrary. The air vents 74 open into the cavity forming wall surface 61. Furthermore, between adjacent vent grooves 80 in the circumferential direction on the outer circumferential surface 82 of the tip of the outer pin 72, fitting surfaces 81 are formed that contact and engage with the wall surface of the pin mounting hole 71. The fitting surfaces 81 are tightly fitted to the wall surface of the pin mounting hole 71 without any gaps.

[0040] An outer small-diameter portion 83 is formed on the base end side of the outer peripheral surface 82 of the tip of the outer pin 72. The outer small-diameter portion 83 is continuous with the base end side of the outer peripheral surface 82 of the tip of the outer pin 72. That is, the outer small-diameter portion 83 is formed continuously with the base end side of the vent groove 80 and the fitting surface 81. The outer small-diameter portion 83 has a smaller diameter than the outer peripheral surface 82 of the tip of the outer pin 72. That is, the outer small-diameter portion 83 has a smaller diameter than the diameter of the fitting surface 81. An annular outer gap 76 is formed between the outer small-diameter portion 83 and the wall surface of the pin mounting hole 71. The outer annular gap 76 communicates with the outside of the upper mold 4, and the air vent 74 communicates with the outer annular gap 76. In addition, an outer large-diameter portion 84 is formed on the base end side of the outer small-diameter portion 83. The outer large-diameter portion 84 has a larger diameter than the outer small-diameter portion 83. The outer pin 72 is cylindrical, and an inner pin mounting hole 85 into which the inner pin 73 is inserted is formed extending to the tip surface. The inner pin 73 is inserted into the inner pin mounting hole 85.

[0041] The outer circumferential surface of the inner pin 73 overlaps the inner circumferential surface of the outer pin 72. As shown in Figures 13 and 16, numerous internal vent grooves 90 are formed on the outer circumferential surface 92 of the tip of the inner pin 73 at regular intervals in the circumferential direction. The internal vent grooves 90 are arc-shaped in cross-section, similar to the vent grooves 80. The bottom surface of the internal vent grooves 90 is not a flat surface, but a concave curved surface that curves toward the center of the inner pin 73. The internal vent grooves 90 extend linearly along the axial direction of the inner pin 73. As a result of the formation of numerous internal vent grooves 90 on the outer circumferential surface 92 of the tip of the inner pin 73, numerous internal air vents 75 are formed between the outer circumferential surface 92 of the tip of the inner pin 73 and the inner circumferential surface of the tip of the outer pin 72. In this embodiment, eight internal air vents 75 are formed, but the number is arbitrary. The internal air vents 75 open into the cavity forming wall surface 61. Furthermore, between adjacent inner vent grooves 90 in the circumferential direction on the outer peripheral surface 92 of the tip of the inner pin 73, inner fitting surfaces 91 are formed that contact and fit with the inner peripheral surface of the tip of the outer pin 72. The inner fitting surfaces 91 are tightly fitted to the inner peripheral surface of the tip of the outer pin 72 without any gaps.

[0042] An inner small-diameter portion 93 is formed on the base end side of the outer peripheral surface 92 of the tip of the inner pin 73. The inner small-diameter portion 93 is continuous with the base end side of the outer peripheral surface 92 of the tip of the inner pin 73. That is, the inner small-diameter portion 93 is formed continuously with the base end side of the inner vent groove 90 and the inner fitting surface 91. The inner small-diameter portion 93 has a smaller diameter than the outer peripheral surface 92 of the tip of the inner pin 73. That is, the inner small-diameter portion 93 has a smaller diameter than the diameter of the inner fitting surface 91. An annular inner gap 77 is formed between the outer peripheral surface of the inner small-diameter portion 93 and the inner peripheral surface of the outer pin 72.

[0043] A first inner large-diameter portion 94 is formed at the base end of the inner small-diameter portion 93. The first inner large-diameter portion 94 has a larger diameter than the inner small-diameter portion 93. Furthermore, a second inner large-diameter portion 95 is formed at the base end of the first inner large-diameter portion 94. The second inner large-diameter portion 95 has a larger diameter than the first inner large-diameter portion 94.

[0044] A lateral hole 96 is formed in the inner small-diameter portion 93. The lateral hole 96 is perpendicular to the axial direction of the inner pin 73 and penetrates the inner small-diameter portion 93. Therefore, the lateral hole 96 is a through hole passing through the center of the inner small-diameter portion 93. The lateral hole 96 opens at two locations on the outer circumferential surface of the inner small-diameter portion 93, opposite each other at 180 degrees.

[0045] Furthermore, an axial hole 97 is formed in the inner pin 73. The axial hole 97 is formed on the center line of the inner pin 73, communicates with the lateral hole 96, and extends from the lateral hole 96 toward the base end of the inner pin 73. Therefore, the inner pin 73, including the inner small diameter portion 93, is mostly cylindrical toward the base end.

[0046] As described above, in the casting apparatus 1 of this embodiment, a gas venting pin 70 is detachably attached to the mold 2, and an air vent 74 is formed by forming a vent groove 80 on the outer circumferential surface of the tip of the gas venting pin 70. Therefore, the gas in the cavity 6 can be efficiently discharged to the outside of the mold 2 through the air vent 74, thereby improving the quality of the product.

[0047] In particular, in this embodiment, the venting pin 70 is provided on the upper mold 4. Therefore, gas that tends to accumulate in the cavity 6, especially on the upper mold 4 side, can be efficiently discharged from the venting pin 70. Also, the venting pin 70 extends from the cavity 6 toward the shutter 18 side. Therefore, when the mold 2 tilts to a vertical state as shown in Figures 8 and 9, the venting pin 70 extends upward from the cavity 6 to the end face of the upper mold 4. Consequently, in the vertical state, gas accumulated in the upper part of the cavity 6 can be efficiently discharged upward from the end face of the upper mold 4 by the venting pin 70.

[0048] Furthermore, the tie rod arm 115 extends radially outward and laterally from the bearing support portion 110. Therefore, the area in the cavity 6 where the tie rod arm 115 is formed is an area where molten metal M does not easily spread when the mold 2 is tilted. The tie rod connecting portion 113 is at the tip of the tie rod arm 115, and the area where the tie rod connecting portion 113 is formed is far from the pressure pin 23. Therefore, by placing the gas vent pin 70 at the area where the tie rod connecting portion 113 is formed, gas at the area where the tie rod connecting portion 113 is formed can be efficiently discharged, and the quality of the tie rod connecting portion 113 can be improved. Consequently, the quality of the knuckle 101, which is an important safety component, can be improved. In particular, in this embodiment, since most of the tie rod connecting portion 113 is formed by the upper mold 4, it is susceptible to the effects of gas accumulation, but since the gas vent pin 70 is placed at that location, the quality of the tie rod connecting portion 113 can be easily improved.

[0049] Furthermore, the gas release pin 70 is detachably attached to the upper mold 4. Therefore, the gas release pin 70 can be periodically removed from the upper mold 4 to perform maintenance such as cleaning the air vent 74. In particular, removing burrs of molten metal adhering to the vent groove 80 can eliminate blockages in the air vent 74.

[0050] Furthermore, the vent groove 80 is formed in an arc shape when viewed in cross-section. That is, the bottom surface of the vent groove 80 is not flat, but a curved surface that curves concavely toward the center of the gas vent pin 70. Therefore, the opening area of ​​the air vent 74 can be easily secured without excessively widening the width of the vent groove 80. If the vent groove 80 were formed by a D-cut, the bottom surface of the vent groove 80 would be flat, making it difficult to secure the depth of the vent groove 80 and thus difficult to secure a large opening area. In contrast, by forming the vent groove 80 in an arc shape when viewed in cross-section, the depth of the vent groove 80 can be easily increased, and the opening area can be easily secured.

[0051] Furthermore, by making the vent groove 80 arc-shaped in cross-section, the opening area at both circumferential ends of the air vent 74 can be increased. As a result, the occurrence of burr clogging at both circumferential ends of the air vent 74 can be suppressed, and even if burr clogging occurs, the burr can be easily removed during maintenance.

[0052] Furthermore, between adjacent vent grooves 80 in the circumferential direction, a fitting surface 81 is formed that fits into surface contact with the wall surface of the pin mounting hole 71. As a result, the fitting surface 81 of the gas vent pin 70 can be brought into close contact with the wall surface of the pin mounting hole 71, resulting in a gap-free fitting state between the gas vent pin 70 and the wall surface of the pin mounting hole 71. Moreover, since the vent groove 80 has an arc shape in cross-section, it is not necessary to excessively enlarge the circumferential dimensions of the vent groove 80, so that a large circumferential dimension of the fitting surface 81 can be secured. As a result, the gas vent pin 70 can be firmly in surface contact with the pin mounting hole 71 without any gaps.

[0053] Furthermore, the gas vent pin 70 has a double-layer structure, with an inner air vent 75 provided radially inside the air vent 74. As a result, gas can be efficiently discharged to the outside by the air vent 74 and the inner air vent 75.

[0054] The inner pin 73 can be removed from the outer pin 72. Therefore, after removing the gas vent pin 70 from the upper mold 4, the inner pin 73 can be further removed from the outer pin 72 for maintenance. Because the inner vent groove 90 has an arc shape in cross-section, the opening area at both circumferential ends of the inner air vent 75 can be increased, which suppresses the occurrence of burr clogging at both circumferential ends of the inner air vent 75, and even if burr clogging occurs, the burr can be easily removed during maintenance.

[0055] Similar to the vent groove 80, the inner vent groove 90 is also formed in an arc shape in cross-section. Therefore, the opening area of ​​the inner air vent 75 can be easily secured without excessively increasing the width of the inner vent groove 90. In addition, since an inner fitting surface 91 is formed between adjacent inner vent grooves 90 in the circumferential direction, the inner fitting surface 91 can be brought into close contact with the inner circumferential surface of the tip of the outer pin 72, resulting in a gap-free fitting state between the outer pin 72 and the inner pin 73. Moreover, because the inner vent groove 90 is arc-shaped in cross-section and does not require excessive enlargement of its circumferential dimensions, the circumferential dimensions of the inner fitting surface 91 can be made larger, allowing the inner pin 73 to be firmly attached to the outer pin 72 in gap-free surface contact.

[0056] Furthermore, an outer small-diameter portion 83 is formed on the base end side of the outer peripheral surface 82 of the tip of the outer pin 72. As a result, the gas in the cavity 6 passes through numerous air vents 74, is collected in the outer annular gap 76, and then discharged to the outside of the upper mold 4. By providing the outer small-diameter portion 83 in this way, the axial length of the vent groove 80 can be shortened, making it easier to machine the vent groove 80.

[0057] Similarly, by providing an inner small-diameter portion 93 in the inner pin 73, gas can be concentrated in the inner annular gap 77 before being discharged. In addition, by providing the inner small-diameter portion 93, the length of the inner vent groove 90 can be shortened, making it easier to machine the inner vent groove 90. Furthermore, since gas is discharged to the outside through the lateral hole 96 and the axial hole 97, gas can be discharged efficiently. [Explanation of symbols]

[0058] 1. Casting apparatus 2 molds 3 Lower mold 4 Upper mold 5 Yudo 6 Cavity 7 Ladle 8 Base 9 Guide axis 10 Top Plate 11. First hydraulic cylinder 12. First Cylinder Rod 13 Movable Plate 14 Connecting members 15. Second hydraulic cylinder 16. Second Cylinder Rod 18 shutters 20 Third hydraulic cylinder 21 Third Cylinder Rod 23 Pressure pin 50. Fourth hydraulic cylinder 51. Fourth Cylinder Rod 53 Auxiliary pressure pin 60 Cylindrical protrusions 61 Cavity-forming wall 62. Second circular recess 70 Gas release pin 70a Tip surface 71 pin mounting holes 72 Outer pin 73 Inner Pin 74 Air vents 75 Internal air vent 76 Outer ring gap 77 Inner annular gap 80 Bent grooves 81 Mating surface 82 Tip outer circumferential surface 83 Outer small diameter section 84 Outer large diameter section 85 Inner pin mounting holes 90 Internal vent groove 91 Inner mating surface 92 Tip outer circumferential surface 93 Inner small diameter section 94 First inner large diameter section 95 Second inner large diameter section 96 Horizontal hole 97 Axial hole 100 Suspension system 101 Knuckle 101a 1st page 101b 2nd page 102 wheels 103 Disc rotor 104 Brake caliper 105 Damper 106 Lower Arm 107 Tie Rod 110 Bearing support section (main body) 111 Damper connection section 112 Lower arm connection 113 Tie rod connection 114 Caliper connection part 115 Tie rod arm (arm section) 120 Main hole 121 1st connection hole 122 2nd connection hole 123 3rd connection hole 124 4th connecting hole 125 5th connecting hole M molten metal

Claims

1. A degassing mechanism in a tilting gravity casting apparatus in which molten metal is stored in the ladle of the mold and poured into the cavity of the mold through the runner by tilting the mold, A gas venting pin is removably mounted in the pin mounting hole of the mold, with its tip facing the cavity. The outer circumferential surface of the tip of the gas vent pin has multiple vent grooves formed at circumferential intervals, extending to the tip surface of the gas vent pin, and between adjacent vent grooves, there are fitting surfaces that engage with the wall surface of the pin mounting hole. The vent groove and the wall surface of the pin mounting hole form an air vent for releasing gas from the cavity. The vent groove is a gas venting mechanism for a tilting gravity casting apparatus, and its cross-sectional view is arc-shaped.

2. The gas vent pin comprises a cylindrical outer pin with a vent groove and a fitting surface formed on the outer circumference of its tip, and an inner pin mounted radially inward of the outer pin. Multiple internal vent grooves are formed on the outer circumferential surface of the tip of the inner pin, extending to the tip of the gas vent pin, and are spaced apart in the circumferential direction. Between adjacent internal vent grooves, internal fitting surfaces are formed that make surface contact with the inner circumferential surface of the outer pin and engage with it. An internal air vent is formed by the internal vent groove and the inner circumferential surface of the outer pin, allowing gas to escape from the cavity. The gas venting mechanism of the tilting gravity casting apparatus according to claim 1, wherein the internal vent groove is arc-shaped in cross-section.

3. A gas venting mechanism for a tilting gravity casting apparatus according to claim 2, wherein an outer small-diameter portion is formed on the base end side of the outer circumferential surface of the tip of the outer pin, and gas is discharged to the outside through an annular gap between the outer small-diameter portion and the wall surface of the pin mounting hole from the air vent.

4. The mold comprises an upper mold located on the upper side before being tilted, and a lower mold located on the lower side before being tilted. A venting pin is provided in the upper mold, in the venting mechanism of the tilting gravity casting apparatus according to any one of claims 1 to 3.

5. The upper mold is equipped with a shutter that blocks the runner. The degassing pin extends along the direction from the cavity toward the shutter side, the degassing mechanism of the tilting gravity casting apparatus according to claim 4.

6. The mold is equipped with pressure pins that press the molten metal in the cavity in the clamping direction. The casting has a main body formed at the point where the pressure pin presses, and an arm extending radially outward from the main body towards the pressure pin. The gas venting mechanism of the tilting gravity casting apparatus according to claim 1, wherein the gas venting pin is positioned at the location that forms the tip of the arm portion.

7. The casting is a steering knuckle for a vehicle. The main body is a bearing support that rotatably supports the wheel hub, and the arm is a tie rod arm having a tie rod connecting part at its tip to which a tie rod is connected. The pressure pin is positioned at the location that forms the bearing support. The gas venting mechanism of the tilting gravity casting apparatus according to claim 6, wherein the gas venting pin is positioned at the location forming the tie rod connection.

Images