Die casting apparatus and method for manufacturing cast product

Abstract

To provide a die casting apparatus capable of suppressing the occurrence of gas cavity in the cast product, and a method for manufacturing a cast produce.SOLUTION: A die casting apparatus 1 replaces an interior of a cavity 11A of a mold 11 with oxygen, fills the cavity 11A with molten metal A1, and manufactures cast products B1 to B3. A first chill block 81 having a first chill die surface 81A is provided on a fixed die 12, and a second chill block 82 having a second chill die surface 82A is provided on a movable die 13. In a state in which the mold 11 is clamped, the cavity 11A is partitioned between a fixed die surface 12A of the fixed die 12 and a movable die surface 13A of the movable die 13, and a chill-vent discharge passage 72 communicating with the cavity 11A is partitioned between the first chill die surface 81A and the second chill die surface 82A. In a state in which the mold 11 is clamped, one of the first chill block 81 and the second chill block 82 is configured to be movable toward and away from the other in a mold-clamping direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a die-casting machine and a method for manufacturing a casting. [Background technology]

[0002] Patent Document 1 discloses a conventional die-casting device. This die-casting device supplies oxygen into the cavity of a mold, and then replaces the gas inside the cavity with oxygen by discharging the gas outside through an exhaust path, and then fills the cavity with molten aluminum to produce a casting.

[0003] This die-casting machine is equipped with a chill vent in the exhaust path for discharging gas from the cavity. The chill vent discharges gases such as nitrogen contained in the molten aluminum to the outside via a chill vent exhaust path that communicates with the cavity. This prevents the formation of gas porosity in the casting.

[0004] At this time, when almost all of the gas in the cavity is discharged and the molten aluminum reaches the chill vent outlet, the molten aluminum that has flowed into the chill vent outlet is rapidly cooled and solidified, thereby preventing the molten aluminum from leaking out of the chill vent outlet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-223610 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional die-casting apparatus, solidified aluminum melt may remain stuck in the chill vent. This reduces the cross-sectional area of ​​the chill vent, potentially resulting in insufficient gas removal from the chill vent and insufficient oxygen replacement within the cavity. This may make it difficult to prevent gas porosity in the casting.

[0007] The present invention has been made in view of the above-mentioned conventional circumstances, and an object to be achieved is to provide a die-casting apparatus and a method for manufacturing a cast product that can suppress the generation of gas porosity in the cast product. [Means for solving the problem]

[0008] The die-casting apparatus of the present invention is a die-casting apparatus for producing a casting by supplying oxygen into a cavity of a mold and discharging gas inside the cavity to the outside through an exhaust path including a chill vent exhaust path, thereby replacing the atmosphere inside the cavity with oxygen, and filling the cavity with molten metal, The mold includes a fixed mold having a fixed mold surface and a movable mold having a movable mold surface and movable toward and away from the fixed mold in a mold clamping direction, the fixed mold is provided with a first chill block having a first chill mold surface; the movable mold is provided with a second chill block having a second chill mold surface; When the mold is clamped, the cavity is defined between the fixed mold surface and the movable mold surface, and the chill vent discharge path communicating with the cavity is defined between the first chill mold surface and the second chill mold surface, The mold is characterized in that, when the mold is clamped, one of the first chill block and the second chill block is movable forward and backward in the mold clamping direction relative to the other.

[0009] In the die-casting apparatus of the present invention, when the mold is clamped, one of the first chill block and the second chill block can move back and forth relative to the other in the mold clamping direction, and the flow path cross-sectional area of ​​the chill vent discharge channel defined between the first chill mold surface and the second chill mold surface is variable. Therefore, even if solidified molten metal remains stuck in the chill vent discharge channel, by moving one of the first chill block and the second chill block back relative to the other in the mold clamping direction to expand the flow path cross-sectional area of ​​the chill vent discharge channel, insufficient gas release from the chill vent discharge channel can be prevented. As a result, insufficient oxygen replacement in the cavity can be prevented.

[0010] Therefore, the die casting apparatus of the present invention can suppress the occurrence of gas porosity in the casting.

[0011] The fixed mold is preferably provided with a stationary release pin. The first chill block is preferably supported by the fixed mold so as to be movable back and forth in the mold clamping direction. The first chill block is preferably formed with an insertion hole that opens onto the first chill mold surface and through which the release pin slides. When the first chill block is in a forward position advanced in the mold clamping direction, the tip surface of the release pin inserted into the insertion hole preferably forms part of the first chill mold surface. When the first chill block is in a retracted position retracted in the mold clamping direction, the tip of the release pin preferably protrudes from the first chill mold surface.

[0012] In this case, for example, after casting, when the mold is opened, the first chill block in the advanced position can be moved to the retracted position, allowing the solidified molten metal on the first chill mold surface to be pushed out and removed with the mold release pin. Alternatively, when the molten metal filled in the cavity is in the middle of solidification and shrinkage, the first chill block in the advanced position can be moved to the retracted position, allowing the semi-solidified molten metal to be peeled off from the first chill mold surface with the mold release pin. This prevents the solidified molten metal from adhering to and remaining on the first chill mold surface. As a result, it is possible to more reliably prevent insufficient gas removal from the chill vent exhaust passage, resulting in insufficient oxygen replacement in the cavity.

[0013] The fixed mold preferably has a receiving hole that opens to the fixed mold surface. The first chill block is preferably received in the receiving hole and supported by the fixed mold so as to be movable back and forth in the mold clamping direction. The receiving hole preferably has a tapered inner surface that extends while gradually widening the distance therebetween as it moves away from the fixed mold surface in the mold clamping direction. The first chill block preferably has a tapered outer surface that comes into sliding contact with the tapered inner surface when it moves back and forth in the mold clamping direction.

[0014] If the sliding contact surface between the fixed mold and the first chill block when the first chill block moves forward or backward relative to the fixed mold extends parallel to the mold clamping direction, burrs adhering to the sliding contact surface can easily become trapped and impede the movement of the first chill block moving forward or backward in the mold clamping direction. In this regard, in this die-casting apparatus, the accommodation hole in the fixed mold surface that accommodates the first chill block so that it can slide widens in the direction in which the first chill block retreats. Therefore, even if burrs are adhering to the sliding contact surface, the first chill block can easily escape from the accommodation hole when it retreats. As a result, malfunctions of the first chill block due to burrs can be suppressed.

[0015] The die casting machine of the present invention preferably includes an air injection device for blowing air onto the tapered inner surface and the tapered outer surface.

[0016] In this case, after the casting process is completed and the mold is opened, for example, with the first chill block in the retracted position, the air injection device can blow air onto the tapered inner side surface and the tapered outer side surface, thereby blowing away burrs on the sliding surface between the tapered inner side surface and the tapered outer side surface and preventing burrs from adhering to the sliding surface, thereby further preventing malfunction of the first chill block due to burrs getting caught.

[0017] The die-casting apparatus of the present invention preferably includes a squeeze pin that locally pressurizes the molten metal filled in the cavity. The discharge path preferably includes a squeeze pin discharge passage formed in the squeeze pin. The squeeze pin discharge passage preferably communicates with the interior of the cavity when the squeeze pin has advanced into the cavity, thereby discharging gas from the cavity, and preferably blocks communication with the interior of the cavity when the squeeze pin has retracted from the cavity.

[0018] In this case, the squeeze pin discharge path formed in the squeeze pin communicates with the inside of the cavity when the squeeze pin is inserted into the cavity. Then, when oxygen is supplied into the cavity, the squeeze pin discharge path discharges gas from the cavity. Therefore, by locating the squeeze pin in a part of the cavity that is prone to stagnation, the part that is prone to stagnation can be more effectively replaced with oxygen.

[0019] The discharge path preferably includes an external discharge path connected to the chill vent discharge path. The die casting apparatus of the present invention preferably includes a control valve that can open and close the external discharge path. The control valve preferably closes the external discharge path when the squeeze pin discharge path communicates with the inside of the cavity.

[0020] In this case, a period can be set in which the gas in the cavity is discharged only through the squeeze pin discharge passage, so that the stagnant portion of the cavity can be more effectively replaced with oxygen.

[0021] The method for producing a casting of the present invention is a method for producing a casting using the die-casting apparatus of the present invention, an oxygen replacement step of replacing the inside of the cavity with oxygen by supplying oxygen into the cavity of the mold and discharging the gas inside the cavity to the outside through the exhaust path including the chill vent exhaust path; a casting step of filling the cavity with the molten metal to produce the casting, the oxygen replacement step includes a chill vent discharge step of discharging gas from the cavity through the chill vent discharge path while the mold is clamped and one of the first chill block and the second chill block is in a retracted position retracted in the mold clamping direction relative to the other chill block, The casting process is characterized by including a molten metal filling process in which molten metal is filled into the cavity while the mold is clamped and one of the first chill block and the second chill block is in an advanced position advanced in the mold clamping direction relative to the other.

[0022] In the method for manufacturing a casting of the present invention, the casting process includes a molten metal filling process in which the cavity is filled with molten metal while the mold is clamped and one of the first chill block and the second chill block is in an advanced position advanced relative to the other. In this molten metal filling process, the molten metal is effectively prevented from leaking out of the cavity through the chill vent discharge passageway because one of the first chill block and the second chill block is in the advanced position. The oxygen replacement process includes a chill vent discharge process in which gas within the cavity is discharged through the chill vent discharge passageway while the mold is clamped and one of the first chill block and the second chill block is in a retracted position retreated relative to the other. In this chill vent discharge process, the cross-sectional area of ​​the chill vent discharge passageway is enlarged because one of the first chill block and the second chill block is in the retracted position. Therefore, even if solidified molten metal remains stuck to the chill vent discharge passageway, insufficient gas removal from the chill vent discharge passageway can be prevented. As a result, insufficient oxygen replacement within the cavity can be prevented.

[0023] Therefore, the method for manufacturing a casting of the present invention can suppress the occurrence of gas porosity in the casting.

[0024] In the molten metal filling process, it is preferable to move one of the first chill block and the second chill block, which are in the forward position, back toward the retracted position while the molten metal filled in the cavity is in the middle of solidification and shrinkage.

[0025] In this case, the solidified molten metal can be prevented from clinging to the first chill mold surface of the first chill block or the second chill mold surface of the second chill block as it retracts from the advanced position to the retracted position. This prevents the solidified molten metal from adhering to and remaining in the chill vent discharge passage. In this case, if a stationary release pin is provided on the fixed mold and the first chill block, which has an insertion hole through which the release pin slides, is movable forward and backward, the first chill block can be moved from the advanced position to the retracted position while the molten metal filled in the cavity is in the middle of solidification and shrinkage, allowing the release pin to peel off the semi-solidified molten metal from the first chill mold surface. This further prevents the solidified molten metal from clinging to the first chill mold surface.

[0026] The die-casting apparatus preferably includes a squeeze pin that locally pressurizes the molten metal filled in the cavity. The discharge path preferably includes a squeeze pin discharge passage formed in the squeeze pin. Furthermore, the oxygen substitution step preferably includes a squeeze pin discharge step of communicating the squeeze pin discharge passage with the inside of the cavity while the squeeze pin is inserted into the cavity, and discharging gas inside the cavity via the squeeze pin discharge passage.

[0027] In this case, the oxygen replacement step includes a squeeze pin discharge step of discharging gas inside the cavity through a squeeze pin discharge path formed in the squeeze pin with the squeeze pin inserted into the cavity. In this squeeze pin discharge step, the squeeze pin discharge path communicates with the inside of the cavity, and oxygen is supplied into the cavity, causing the squeeze pin discharge path to discharge the gas inside the cavity. Therefore, by locating the squeeze pin in a part of the cavity where gas is likely to stagnate, the part where gas is likely to stagnate can be more effectively replaced with oxygen.

[0028] The discharge path preferably includes an external discharge path connected to the chill vent discharge path, and the external discharge path is preferably blocked during the squeeze pin discharge step.

[0029] In this case, a period can be provided in the oxygen substitution step during which the gas in the cavity is discharged only through the squeeze pin discharge passage, so that the portion of the cavity that is prone to stagnation can be further substituted with oxygen. [Effects of the Invention]

[0030] The die-casting apparatus and the method for manufacturing a casting of the present invention can suppress the occurrence of gas porosity in a casting. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a schematic cross-sectional view of a die-casting apparatus according to an embodiment, showing the state in which the filling of molten metal is started in the casting process. [Figure 2] FIG. 2 is a partial schematic cross-sectional view of the die-casting apparatus of the embodiment, showing the molds in an open state. [Figure 3] FIG. 3 is a partial schematic cross-sectional view similar to FIG. 2, illustrating the oxygen substitution step. [Figure 4] FIG. 4 is a partial schematic cross-sectional view similar to FIG. 2, illustrating the oxygen substitution step. [Figure 5] FIG. 5 is a partial schematic cross-sectional view similar to FIG. 2, showing the state before the casting step is performed. [Figure 6] FIG. 6 is a partial schematic cross-sectional view similar to FIG. 2, showing a state in which the molten metal has been filled in the casting process. [Figure 7] FIG. 7 is a partial schematic cross-sectional view similar to FIG. 2, showing a state in which the filled molten metal is locally pressurized by a squeeze pin in the casting process. [Figure 8] FIG. 8 is a partial schematic cross-sectional view similar to FIG. 2, showing a state in which the first chill block has been moved to a separated position when the molten metal filled in the casting process is in the middle of solidification and shrinkage. [Figure 9] FIG. 9 is a partial schematic cross-sectional view similar to FIG. 2, showing the mold opened after the casting step. [Figure 10]FIG. 10 is a partial schematic cross-sectional view of the die-casting apparatus of the embodiment, showing the state in which the die is opened after the casting process and air is injected onto the tapered inner side surface and the tapered outer side surface. [Figure 11] FIG. 11 is a schematic side view of the base mold provided in the fixed mold, the mold release pin, and the piston shaft portion of the second piston, as viewed from the mold clamping direction, in the die casting apparatus of the embodiment. [Figure 12] FIG. 12 is a partial schematic plan view showing the shape of the casting in the die casting apparatus of the embodiment at the end of the casting process. [Figure 13] FIG. 13 is a diagram showing the first half of a flowchart illustrating a method for manufacturing a casting of the embodiment using the die-casting apparatus of the embodiment. [Figure 14] FIG. 14 shows the second half of a flowchart illustrating the method for manufacturing a casting of the embodiment using the die-casting machine of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0033] (Example) As shown in FIG. 1 , the die-casting apparatus 1 of the embodiment is an example of a specific embodiment of the "die-casting apparatus" of the present invention. The method for producing a casting B using the die-casting apparatus 1 is an example of a specific embodiment of the "method for producing a casting" of the present invention. The casting B produced by the die-casting apparatus 1 is a pressure-cast product, and in this embodiment, it is an aluminum die-cast product such as a housing or a movable part that constitutes various machines. The present invention is also applicable to castings made of metals other than aluminum.

[0034] 12 shows the shape of a casting A2 in the die-casting apparatus 1 at the end of the casting process. The casting B produced by the die-casting apparatus 1 includes three castings: a first casting B1, a second casting B2, and a third casting B3. That is, the die-casting apparatus 1 simultaneously produces the first to third castings B1 to B3. The die-casting apparatus 1 is provided with a first cavity for molding the first casting B1, a second cavity for molding the second casting B2, and a third cavity for molding the third casting B3, as well as a chill vent discharge passage 72 (described later) that joins the first to third cavities. Therefore, in the casting A2 at the end of the casting process, solidified aluminum C formed by solidification of molten metal A1 in the chill vent discharge passage 72 is connected to the first to third castings B1 to B3. 1 to 10 show cross-sectional views cut at the second cavity, but in the actual die-casting apparatus 1, the first to third cavities are lined up in the depth direction of the paper. Also, the shapes of the runners and the like are simplified in FIGS.

[0035] 1, the die-casting apparatus 1 includes a mold 11, a first hydraulic cylinder 5, a hydraulic control circuit 10C, a squeeze pin 4, a squeeze pin position detector 20, and a die-casting control unit 10. A product removal device 50 that operates in conjunction with the die-casting apparatus 1 is installed near the mold 11.

[0036] As shown in Figures 1 to 10, the mold 11 consists of a fixed mold 12 and a movable mold 13. The fixed mold 12 and the movable mold 13 are held by a mold clamping device (not shown). When the mold clamping device (not shown) is operated, the movable mold 13 moves forward and backward in a mold clamping direction (indicated by an arrow in Figures 1 to 10) relative to the fixed mold 12, bringing it into contact with and away from the fixed mold 12. As shown in Figures 1 and 3 to 6, a cavity 11A corresponding to the second cavity is formed between the fixed mold 12 and the movable mold 13. The cavity 11A is cup-shaped, and a dead-end-shaped portion 11F, which is a bottomed round hole, is formed in the center of the cup shape. Note that the first cavity and the third cavity are also cup-shaped with a dead-end shape, similar to the cavity 11A, which is the second cavity. Similarly to cavity 11A, which is the second cavity, the first cavity and the third cavity also communicate with the interior of plunger sleeve 15 (described later) via a gate and with chill vent discharge path 72.

[0037] As shown in Figure 1 etc., the fixed mold 12 is provided with a plunger sleeve 15 and an injection plunger 16. The plunger sleeve 15 is cylindrical and connected to the fixed mold 12. The injection plunger 16 is housed in the plunger sleeve 15 so as to be able to move forward and backward.

[0038] The internal space of the plunger sleeve 15 communicates with the cavity 11A via a gate 15G. The gate 15G is provided at the lower end of the cup-shaped periphery of the cavity 11A. A pouring port 15H and an oxygen supply hole 15B are formed to penetrate radially through the portion of the plunger sleeve 15 that protrudes from the fixed mold 12.

[0039] As shown in Fig. 3, injection plunger 16 moves back within plunger sleeve 15, thereby connecting the inside of plunger sleeve 15 with oxygen supply hole 15B while closing pouring port 15H. Also, as shown in Figs. 1 and 5, injection plunger 16 moves back further within plunger sleeve 15, thereby opening pouring port 15H. As shown in Fig. 1, with pouring port 15H open, molten metal A1 is supplied into plunger sleeve 15 by ladle 15A.

[0040] 1 and other figures, a push-out pin 13B is provided in the movable mold 13 so as to be able to move forward and backward. Although not shown in the drawings, the push-out pin 13B is able to protrude into the cavity 11A when the movable mold 13 and the fixed mold 12 are in the mold open state.

[0041] As shown in FIG. 1 etc., the first hydraulic cylinder 5 is provided in the fixed mold 12. The first hydraulic cylinder 5 has a first cylinder chamber 5A and a first piston 5B. One end of a first hydraulic pipe 5C is connected to the side of the first cylinder chamber 5A opposite the cavity 11A. One end of a first hydraulic pipe 5D is connected to the side of the first cylinder chamber 5A facing the cavity 11A. The other end of the first hydraulic pipe 5C and the other end of the first hydraulic pipe 5D are connected to a hydraulic control circuit 10C shown in FIG. 1.

[0042] The hydraulic control circuit 10C includes a flow path switching valve, a hydraulic pump, a hydraulic oil tank, etc. (not shown). The first piston 5B is accommodated in the first cylinder chamber 5A so as to be able to move forward and backward. The first cylinder chamber 5A is divided into two by a front surface of the first piston 5B facing the cavity 11A and a back surface of the first piston 5B facing away from the cavity 11A.

[0043] A first stopper 5S is formed on a surface of the first cylinder chamber 5A that faces the front surface of the first piston 5B. The first stopper 5S has a cylindrical shape and protrudes toward the first piston 5B.

[0044] The squeeze pin 4 is a substantially cylindrical shaft body formed integrally with the first piston 5B. The squeeze pin 4 protrudes from the front surface of the first piston 5B toward the cavity 11A. The squeeze pin 4 is disposed at a position that allows it to enter the dead-end passage-shaped portion 11F in the cavity 11A.

[0045] As shown in FIG. 7, hydraulic oil is supplied to the space defined by the back surface of the first piston 5B and the first cylinder chamber 5A via the first hydraulic piping 5C, while hydraulic oil is discharged from the space defined by the front surface of the first piston 5B and the first cylinder chamber 5A via the first hydraulic piping 5D, causing the squeeze pin 4 to move forward and enter the dead-end-shaped portion 11F in the cavity 11A.

[0046] 2, hydraulic oil is further supplied to the space defined by the back surface of the first piston 5B and the first cylinder chamber 5A, while hydraulic oil is further discharged from the space defined by the front surface of the first piston 5B and the first cylinder chamber 5A, causing the squeeze pin 4 to move further forward. Then, when the front surface of the first piston 5B comes into contact with the first stopper 5S and stops, the squeeze pin 4 reaches its farthest point into the dead-end-shaped portion 11F in the cavity 11A, i.e., it has moved to its forward limit.

[0047] The squeeze pin 4 shown in FIGS. 3, 4 and 8 is also in a state where it has penetrated most deeply into the dead-end portion 11F in the cavity 11A, that is, has moved to its forward limit.

[0048] 5, hydraulic oil is supplied via the first hydraulic piping 5D to the space defined by the front surface of the first piston 5B and the first cylinder chamber 5A, while hydraulic oil is discharged via the first hydraulic piping 5C from the space defined by the back surface of the first piston 5B and the first cylinder chamber 5A, causing the squeeze pin 4 to retreat from the dead-end portion 11F in the cavity 11A. Then, the back surface of the first piston 5B comes into contact with and stops against the inner wall surface of the first cylinder chamber 5A that is located on the opposite side to the cavity 11A, causing the squeeze pin 4 to reach a state in which it has retreated most from the dead-end portion 11F in the cavity 11A, i.e., a state in which it has moved to its retreat limit.

[0049] The squeeze pin 4 shown in FIGS. 1 and 6 is also in a state where it is moved most backward from the dead-end portion 11F in the cavity 11A, that is, moved to the backward limit.

[0050] The squeeze pin 4 shown in FIGS. 7 to 9 is in a state where it has entered the dead-end portion 11F in the cavity 11A but has not yet moved to its forward limit.

[0051] 1 is a device separate from the die-casting control unit 10 in this embodiment, and is configured to be able to send and receive various signals to and from the die-casting control unit 10. It is also possible to configure the squeeze pin position detector 20 as a part of the die-casting control unit 10.

[0052] The squeeze pin position detector 20 detects whether the squeeze pin 4 is at the forward limit position shown in FIG. 2 etc., or whether the squeeze pin 4 is at the rear limit position shown in FIG. 1 etc., by means of a position detection sensor (not shown).

[0053] Furthermore, the squeeze pin position detector 20 detects the flow rate of the hydraulic oil circulating in the first hydraulic pipes 5C, 5D using a flow rate sensor 20S shown in FIG. 1, and indirectly detects how far the squeeze pin 4 has advanced from the rear limit position shown in FIG. 1 etc., and how far the squeeze pin 4 has retreated from the front limit position shown in FIG. 2 etc.

[0054] Information on the position of the squeeze pin 4 detected by the squeeze pin position detector 20 is transmitted to the die-casting control unit 10.

[0055] In this die-casting apparatus 1, a chill vent 80 is provided in the mold 11 downstream of the cavity 11A in the flow direction of the molten metal A1 to discharge gas within the cavity 11A and prevent the molten metal A1 from leaking out. Note that in Figures 1 to 10, the up-down direction corresponds to the flow direction of the molten metal A1, the upper side corresponds to the downstream side of the flow direction of the molten metal A1, and the lower side corresponds to the downstream side of the flow direction of the molten metal A1. The flow direction of the molten metal A1 coincides with the flow direction of the gas within the cavity 11A.

[0056] The chill vent 80 includes a first chill block 81, a second chill block 82, a plurality of stationary release pins 83, and a second hydraulic cylinder 6.

[0057] The first chill block 81 is provided on the fixed mold 12. The second chill block 82 is provided on the movable mold 13. The first chill block 81 and the second chill block 82 have a rectangular cross section perpendicular to the mold clamping direction.

[0058] The first chill block 81 has a first chill mold surface 81A on which multiple peaks and valleys are alternately formed. Similarly, the second chill block 82 has a second chill mold surface 82A on which multiple peaks and valleys are alternately formed. The first chill block 81 and the second chill block 82 are arranged so that the first chill mold surface 81A and the second chill mold surface 82A face each other. This forms a serpentine chill vent discharge channel 72 between the first chill mold surface 81A and the second chill mold surface 82A, which continuously extends in the direction of gas flow from the cavity 11A side toward the outside of the mold 11.

[0059] The fixed mold 12 is formed with a receiving hole 17 that opens to the fixed mold surface 12A of the fixed mold 12. The receiving hole 17 has a rectangular cross section perpendicular to the mold clamping direction. A first chill block 81 is received in the receiving hole 17. The first chill block 81 is supported by the fixed mold 12 so as to be movable back and forth in the mold clamping direction within the receiving hole 17. In other words, the first chill block 81 is movable back and forth in the mold clamping direction relative to the second chill block 82.

[0060] The movable die 13 has an accommodating recess 19 formed therein that opens to a movable die surface 13A of the movable die 13. The accommodating recess 19 has a rectangular cross section perpendicular to the die clamping direction. The second chill block 82 is accommodated in the accommodating recess 19. The second chill block 82 is fixed to the movable die 13.

[0061] 2, 10, etc., the accommodation hole 17 has tapered inner surfaces 17A that extend with the distance between them gradually increasing as they move away from the fixed mold surface 12A in the mold clamping direction. The tapered inner surfaces 17A face each other in the vertical direction within the accommodation hole 17. The first chill block 81 also has a tapered outer surface 81B that comes into sliding contact with the tapered inner surface 17A when the first chill block 81 moves back and forth in the mold clamping direction.

[0062] Furthermore, a hollow portion 120 is formed in the fixed mold 12. The hollow portion 120 is in communication with the accommodation hole 17. A block-shaped base mold 18 is accommodated in the hollow portion 120. The base mold 18 is fixed to the fixed mold 12. As shown in FIG. 11 , the cross section of the base mold 18 perpendicular to the mold clamping direction is rectangular.

[0063] 10 and 11, base mold 18 has a base portion 18B on the front surface facing chill vent discharge passage 72, with rectangular frame-shaped peripheral portion 18A remaining, and protruding toward chill vent discharge passage 72. That is, base portion 18B also has a rectangular cross section perpendicular to the mold clamping direction. A plurality of air outlets 92, which will be described later, open into the upper and lower frame portions of rectangular frame-shaped peripheral portion 18A.

[0064] The fixed mold 12 is also provided with a plurality of stationary release pins 83. As shown in FIG. 11, three release pins 83 are provided upstream of a piston shaft 62B (described later) in the gas flow direction, and three release pins 83 are provided downstream of the piston shaft 62B in the gas flow direction. Each release pin 83 is fixed to a base portion 18B of the base mold 18. As shown in FIGS. 2 and 10, the first chill block 81 is formed with a plurality of insertion holes 81C with which each release pin 83 slides. Each insertion hole 81C penetrates the first chill block 81 in the mold clamping direction. The number and positions of the release pins 83 may be changed as appropriate.

[0065] As shown in Figures 1, 10, etc., a second hydraulic cylinder 6 is provided in the fixed mold 12. The second hydraulic cylinder 6 has a second cylinder chamber 6A and a second piston 6B. One end of a second hydraulic pipe 6C is connected to the side of the second cylinder chamber 6A opposite to the chill vent discharge passage 72. One end of a second hydraulic pipe 6D is connected to the side of the second cylinder chamber 6A facing the chill vent discharge passage 72. The other end of the second hydraulic pipe 6C and the other end of the second hydraulic pipe 6D are connected to the hydraulic control circuit 10C shown in Figure 1.

[0066] The second piston 6B is accommodated in the second cylinder chamber 6A so as to be able to move forward and backward. The second piston 6B has a disk-shaped piston base 61B and a substantially cylindrical piston shaft 62B formed integrally with the piston base 61B.

[0067] The second cylinder chamber 6A is divided into two by a front surface of the piston base 61B facing the chill vent discharge passage 72 and a back surface of the piston base 61B facing the opposite side from the chill vent discharge passage 72. A second stopper 6S is formed on the surface of the second cylinder chamber 6A facing the front surface of the piston base 61B. The second stopper 6S has a cylindrical shape and protrudes toward the piston base 61B. The piston shaft 62B protrudes from the front surface of the piston base 61B toward the chill vent discharge passage 72. The tip of the piston shaft 62B is exposed from the base portion 18B and is fixed to the back surface of the first chill block 81 facing the opposite side from the chill vent discharge passage 72.

[0068] As shown in FIG. 5 , hydraulic oil is supplied to the space defined by the back surface of the piston base 61B and the second cylinder chamber 6A via the second hydraulic piping 6C, while hydraulic oil is discharged from the space defined by the front surface of the piston base 61B and the second cylinder chamber 6A via the second hydraulic piping 6D, causing the second piston 6B to advance in the mold clamping direction toward the chill vent discharge passage 72. As a result, the piston shaft 62B of the second piston 6B advances the first chill block 81 in the mold clamping direction toward the second chill block 82. Then, when the front surface of the piston base 61B abuts against the second stopper 6S, the second piston 6B reaches its most advanced state toward the chill vent discharge passage 72, i.e., reaches its forward limit. The first chill block 81 reaches its most advanced position toward the second chill block 82. With first chill block 81 in the advanced position, the tip surface of release pin 83 inserted through insertion hole 81C forms part of first chill mold surface 81A. With first chill block 81 in the advanced position, the clearance of chill vent discharge path 72 defined between first chill mold surface 81A and second chill mold surface 82A is set to a desired set value.

[0069] In Figures 1, 2, 6 and 7, the second piston 6B is in its most advanced state toward the chill vent discharge passage 72, i.e., it has moved to its forward limit, and the first chill block 81 is in its most advanced position toward the second chill block 82.

[0070] As shown in FIG. 3 , hydraulic oil is supplied to the space defined by the front surface of the piston base 61B and the second cylinder chamber 6A via the second hydraulic piping 6D, while hydraulic oil is discharged from the space defined by the back surface of the piston base 61B and the second cylinder chamber 6A via the second hydraulic piping 6C, causing the second piston 6B to retract toward the side opposite the chill vent discharge passage 72. As a result, the piston shaft 62B of the second piston 6B retracts the first chill block 81 in the mold clamping direction toward the side opposite the second chill block 82. Then, the back surface of the piston base 61B abuts against the inner wall surface of the second cylinder chamber 6A located on the side opposite the chill vent discharge passage 72, causing the second piston 6B to move all the way back toward the side opposite the chill vent discharge passage 72, i.e., to the retract limit. Furthermore, the first chill block 81 is in a retracted position, the farthest retracted from the second chill block 82. As shown in FIG. 10, with the first chill block 81 in the retracted position, the tip of the release pin 83 inserted through the insertion hole 81C protrudes a predetermined amount from the first chill mold surface.

[0071] In Figures 4, 8, 9 and 10, the second piston 6B is in its most retracted position toward the opposite side of the chill vent discharge passage 72, i.e., it has moved to its most retracted position, and the first chill block 81 is in its most retracted position away from the second chill block 82.

[0072] 1, the die-casting apparatus 1 further includes an air supply device 90, an air passage 91, and a plurality of air outlets 92. The air supply device 90, the air passage 91, and the air outlets 92 constitute the "air injection device" of the present invention.

[0073] As shown in FIGS. 10 and 11 , an air passage 91 and air outlets 92 are provided in the base mold 18. Two air outlets 92 are arranged in the peripheral edge 18A above the base portion 18B, and two air outlets 92 are arranged in the peripheral edge 18A below the base portion 18B. The air passage 91 extends downward from an inlet 91A that opens to the outside of the mold 11 on the upper surface of the base mold 18, and extends in a roughly U-shaped frame shape around the peripheral edge 18A to surround the base portion 18B. The air passage 91 extends in the mold clamping direction from the U-shaped frame to each air outlet 92 at positions corresponding to the air outlets 92. An air supply device 90 is connected to the inlet 91A of the air passage 91. The number and positions of the air outlets 92 may be changed as appropriate.

[0074] In this way, air supplied from the air supply device 90 flows into the air passage 91 from the inlet 91A and is blown out from each air outlet 92. Then, from the two air outlets 92 arranged above the base 18B, air is blown out upward (downstream in the gas flow direction) toward the tapered inner side surface 17A and tapered outer side surface 81B. Also, from the two air outlets 92 arranged below the base 18B, air is blown out downward (upstream in the gas flow direction) toward the tapered inner side surface 17A and tapered outer side surface 81B.

[0075] The die-casting control unit 10 shown in FIG. 1 includes a processing unit such as a CPU, storage devices such as a ROM, a RAM, and a HDD, and a control device that controls an electric motor, a hydraulic pump, an electromagnetic valve, and the like.

[0076] The die-casting control unit 10 controls the clamping and mold opening operations of a clamping device (not shown), the forward and backward movement of the injection plunger 16, the pouring operation of the ladle 15A, the forward and backward movement of the ejection pin 13B, the forward and backward movement of the first chill block 81, and the air supply of the air supply device 90.

[0077] Furthermore, the die-casting control unit 10 operates the hydraulic control circuit 10C while referring to the position information of the squeeze pin 4 detected by the squeeze pin position detector 20, thereby controlling the advance and retreat movement of the squeeze pin 4.

[0078] 1, the die casting apparatus 1 further includes an oxygen supply control device 40, a squeeze pin discharge passage 71, a chill vent discharge passage 72, a squeeze pin connection discharge passage 73, an external discharge passage 74, an oxygen concentration measuring device 30, a ventilation control valve 73V, and a control valve 72V, all of which are used to perform a pore-free die casting method.

[0079] In this embodiment, the oxygen supply control device 40 is a separate device from the die-casting control unit 10, and is configured to be able to send and receive various signals to and from the die-casting control unit 10. It is also possible to configure the oxygen supply control device 40 as a part of the die-casting control unit 10.

[0080] The oxygen supply control device 40 includes a processing unit such as a CPU, a storage device such as a ROM, RAM, or HDD, and a solenoid valve that controls the supply of oxygen from an oxygen supply source (not shown). The oxygen supply control device 40 connects the oxygen supply source (not shown) to the oxygen supply hole 15B of the plunger sleeve 15 via an oxygen supply path 41.

[0081] As shown in Figures 3 and 4, the oxygen supply control device 40 supplies oxygen into the cavity 11A through the oxygen supply path 41 when the injection plunger 16 is retracted to close the pouring port 15H and the inside of the plunger sleeve 15 is connected to the oxygen supply hole 15B.

[0082] The squeeze pin discharge passage 71, the chill vent discharge passage 72, the squeeze pin connecting discharge passage 73, and the external discharge passage 74 constitute a discharge path for discharging the gas inside the cavity 11A to the outside of the mold 11.

[0083] The squeeze pin discharge passage 71 includes a plurality of linear grooves 71A and an annular groove 71B. Each linear groove 71A is recessed into the outer peripheral surface of the squeeze pin 4 and extends in the axial direction of the squeeze pin 4. The annular groove 71B is recessed so as to go around the entire outer peripheral surface of the squeeze pin 4 and is in communication with each linear groove 71A.

[0084] The end of each linear groove 71A of the squeeze pin discharge passage 71 on the cavity 11A side communicates with the inside of the cavity 11A when the squeeze pin 4 is fully inserted into the dead-end portion 11F in the cavity 11A, that is, when it has moved to its forward limit.

[0085] On the other hand, as shown in FIG. 1 etc., the end of each linear groove 71A of the squeeze pin discharge path 71 on the cavity 11A side is cut off from communication with the inside of the cavity 11A when the squeeze pin 4 is moved to the most retracted position from the dead-end-shaped portion 11F in the cavity 11A, that is, when it has moved to its retraction limit.

[0086] Although not shown, the connection and disconnection between the cavity 11A side end of each linear groove 71A and the cavity 11A is switched while the squeeze pin 4 is moving between the forward limit and the backward limit.

[0087] 1 to 10, one end of a squeeze pin connecting discharge path 73 is connected to a portion of each linear groove 71A of the squeeze pin discharge path 71 that is spaced from the cavity 11A regardless of the advancement and retreat of the squeeze pin 4. The squeeze pin connecting discharge path 73 is formed inside the mold 11 so as to be connected in series to the squeeze pin discharge path 71, and extends to the outside of the mold 11.

[0088] 1, the oxygen concentration measuring device 30 is connected to the other end of the squeeze pin connecting discharge path 73. In this embodiment, the oxygen concentration measuring device 30 is a device separate from the die-casting control device 10, but it can also be configured as a part of the die-casting control device 10. Also, in this embodiment, the oxygen concentration measuring device 30 is a device separate from the oxygen supply control device 40, but it can also be configured as a part of the oxygen supply control device 40. The oxygen concentration measuring device 30 is configured to be able to send and receive various signals to and from the oxygen supply control device 40.

[0089] The oxygen concentration measuring device 30 measures the oxygen concentration M1 of the gas discharged to the squeeze pin connecting discharge path 73 via the squeeze pin discharge path 71. The oxygen concentration measuring device 30 can be appropriately selected from a number of types of oxygen sensors that measure oxygen concentration using various measurement principles. The configurations of these oxygen sensors are well known, so a description thereof will be omitted.

[0090] The ventilation control valve 73V is connected to the other end of the squeeze pin connecting discharge path 73. The ventilation control valve 73V opens and closes in response to a control signal from the oxygen supply control device 40, allowing the squeeze pin connecting discharge path 73 to be ventilated.

[0091] The opening and closing control of the ventilation control valve 73V is appropriately selected to improve the accuracy of oxygen concentration measurement by the oxygen concentration measuring device 30. In this embodiment, the ventilation control valve 73V temporarily opens to ventilate the squeeze pin connecting discharge path 73 before the oxygen concentration measuring device 30 measures the oxygen concentration M1 of the gas discharged to the squeeze pin connecting discharge path 73 via the squeeze pin discharge path 71.

[0092] Chill vent discharge path 72 is a passage formed between a first chill block 81 provided on fixed mold 12 and a second chill block 82 provided on movable mold 13 when mold 11 is clamped. The lower end of chill vent discharge path 72 is connected to the upper end of the cup-shaped periphery of cavity 11A. The upper end of chill vent discharge path 72 extends upward to the upper ends of fixed mold 12 and movable mold 13 and is connected to external discharge path 74. In other words, chill vent discharge path 72 and external discharge path 74 communicate between the inside of cavity 11A and the outside of mold 11, separately from squeeze pin discharge path 71 and squeeze pin connection discharge path 73.

[0093] The control valve 72V is connected to the external discharge path 74. The control valve 72V is controlled by the die-casting control unit 10, and is capable of opening and closing the external discharge path 74 in response to a control signal from the oxygen supply control device 40.

[0094] The opening and closing control of the control valve 72V is appropriately selected to improve the oxygen replacement efficiency in the cavity 11A when the oxygen supply control device 40 supplies oxygen into the cavity 11A. In this embodiment, the control valve 72V blocks the external discharge path 74 during a part of the period during which the squeeze pin discharge path 71 communicates with the inside of the cavity 11A.

[0095] The die-casting apparatus 1 configured as described above produces the first to third cast products B1 to B3 shown in FIG. 12 by the die-casting control unit 10 and the oxygen supply control device 40 working together to perform control in accordance with the flowcharts shown in FIGS. 13 and 14.

[0096] First, in step S101, the oxygen supply control device 40 performs initial settings for performing the pore-free die casting method. Specifically, the oxygen supply control device 40 sets a predetermined threshold value G1 of the oxygen concentration to be used in step S121, which will be described later. The oxygen supply control device 40 also sets a first supply time T1 and a second supply time T2. The sum of the first supply time T1 and the second supply time T2 is the supply time for supplying oxygen into the cavity 11A. In this embodiment, the first supply time T1 is a variable value. The second supply time T2 is a constant value. Furthermore, the oxygen supply control device 40 sets a lower limit value T1min of the first supply time T1 and a correction value Tcv for the first supply time T1.

[0097] Next, in step S102, the oxygen supply control device 40 temporarily opens the ventilation control valve 73V to ventilate the squeeze pin connection discharge passage 73.

[0098] Next, in step S103, the die-casting control unit 10 operates the hydraulic control circuit 10C to advance the squeeze pin 4. Then, as shown in Fig. 2, the die-casting control unit 10 brings the squeeze pin 4 into a state in which it has penetrated the most into the dead-end-shaped portion 11F in the cavity 11A, that is, moved to its forward limit, thereby connecting the inside of the cavity 11A with the squeeze pin discharge path 71.

[0099] Next, proceeding to step S104, as shown in FIG. 3, the die-casting control unit 10 operates the hydraulic control circuit 10C to retract the first chill block 81 to a retracted position, thereby expanding the flow path cross-sectional area (clearance) of the chill vent discharge passage 72.

[0100] Here, step S104 may be executed after step S112 (described later) and before step S113. That is, after the gas inside cavity 11A is discharged through squeeze pin discharge path 71, first chill block 81 may be moved to the retracted position to expand chill vent discharge path 72.

[0101] Next, proceeding to step S105, the die-casting control unit 10 sprays a release agent onto the opened fixed mold 12 and movable mold 13, and then controls a clamping device (not shown) to clamp the fixed mold 12 and movable mold 13.

[0102] Here, in step S105, the first chill block 81 may be moved back and forth while the release agent is being applied, so that the aluminum solidified material C remaining on the first chill mold surface 81A is pushed out from the first chill mold surface 81A by the release pin 83 and removed.

[0103] Next, in step S106, as shown in Figure 3, the die-casting control unit 10 moves the injection plunger 16 backward, closes the pouring port 15H, and places the inside of the plunger sleeve 15 in communication with the oxygen supply hole 15B. This connects the oxygen supply path 41 of the oxygen supply control device 40 to the plunger sleeve 15.

[0104] Next, in step S107, oxygen supply control device 40 controls control valve 72V to close external discharge path 74 and to close chill vent discharge path 72.

[0105] The following steps S111 to S116 are an example of an "oxygen replacement step" including a "squeeze pin discharge step" and a "chill vent discharge step" of the present invention. That is, in this embodiment, from the beginning to the end of the oxygen replacement step, the squeeze pin discharge step is carried out in which the squeeze pin discharge path 71 is brought into communication with the inside of the cavity 11A with the squeeze pin 4 inserted into the cavity 11A, and gas inside the cavity 11A is discharged via the squeeze pin discharge path 71. More specifically, only the squeeze pin discharge step is carried out in the first half of the oxygen replacement step, and the squeeze pin discharge step and the chill vent discharge step are carried out in the second half of the oxygen replacement step.

[0106] When the process proceeds to step S111, the oxygen supply control device 40 starts supplying oxygen into the cavity 11A and starts timer measurement, as shown in Fig. 3. The gas in the cavity 11A is pushed out by the oxygen that has reached the cavity 11A and is discharged through the squeeze pin discharge path 71 to the squeeze pin connecting discharge path 73.

[0107] Next, in step S112, the oxygen supply control device 40 determines whether the timer measurement time has passed the first supply time T1. If the answer is "No" in step S112, steps S111 and S112 are repeated. On the other hand, if the answer is "Yes" in step S112, the timer measurement is reset and the process proceeds to step S113. The first supply time T1 is also the time during which gas in the cavity 11A, particularly gas stagnating in the dead-end portion 11F, is discharged only through the squeeze pin discharge path 71.

[0108] When the process proceeds to step S113, oxygen supply control device 40 controls control valve 72V to open external discharge path 74 and chill vent discharge path 72, as shown in FIG.

[0109] Next, in step S114, oxygen supply control device 40 continues supplying oxygen into cavity 11A and restarts timer measurement. The gas in cavity 11A is pushed out by the oxygen that has further reached cavity 11A and is discharged through squeeze pin discharge path 71 to squeeze pin connection discharge path 73, and is also discharged to the outside of mold 11 through chill vent discharge path 72 and external discharge path 74.

[0110] Next, in step S115, the oxygen supply control device 40 determines whether the timer measurement time has passed the second supply time T2. If the answer is "No" in step S115, steps S114 and S115 are repeated. On the other hand, if the answer is "Yes" in step S115, the supply of oxygen into the cavity 11A is terminated, the timer measurement is reset, and the process proceeds to step S116. The second supply time T2 is also the time during which the gas in the cavity 11A is discharged via the squeeze pin discharge path 71 and the chill vent discharge path 72.

[0111] In step S116, oxygen supply control device 40 controls control valve 72V to close external discharge path 74 and thus close chill vent discharge path 72. Through steps S111 to S116, the gas in cavity 11A is replaced with oxygen.

[0112] The next step, S120, is an oxygen concentration measurement step. In step S120, the oxygen supply control device 40 transmits a control signal to the oxygen concentration measuring device 30, causing the oxygen concentration measuring device 30 to measure the oxygen concentration M1 of the gas discharged to the squeeze pin connecting discharge path 73 via the squeeze pin discharge path 71. The oxygen supply control device 40 then acquires information about the oxygen concentration M1 measured by the oxygen concentration measuring device 30.

[0113] Next, in step S121, the oxygen supply control device 40 determines whether or not oxygen substitution was successfully performed in the oxygen substitution step. Specifically, the oxygen supply control device 40 determines whether or not the oxygen concentration M1 measured by the oxygen concentration measuring device 30 is greater than a predetermined threshold G1.

[0114] If the answer to step S121 is "Yes," it can be assumed that oxygen replacement has been successfully performed in the dead-end portion 11F of the cavity 11A, which is particularly prone to stagnation. In this case, the oxygen supply control device 40 determines that oxygen replacement has been successfully performed in the oxygen replacement step, and proceeds to step S122.

[0115] On the other hand, if the answer to step S121 is "No," it can be inferred that oxygen replacement was not performed well in the dead-end portion 11F of the cavity 11A, which is particularly prone to stagnation. In this case, the oxygen supply control device 40 determines that oxygen replacement was not performed well in the oxygen replacement process, and proceeds to step S124. The processing of step S124 will be described later.

[0116] When the process proceeds from step S121 to step S122, the oxygen supply control device 40 determines whether the first supply time T1 is equal to the lower limit T1min. If the answer is "No" in step S122, the process proceeds to step S123, where the correction value Tcv is subtracted from the first supply time T1, and then the process proceeds to step S131. This shortens the first supply time T1 in the next oxygen substitution process. As a result, the takt time can be shortened. On the other hand, if the answer is "Yes" in step S122, the process proceeds to step S131 while maintaining the first supply time T1 at the lower limit T1min.

[0117] The following steps S131 to S138 are an example of a "casting step" including a "molten metal filling step" of the present invention. When proceeding to step S131, as shown in Figure 5, the die-casting control unit 10 moves the injection plunger 16 backward to open the pouring port 15H.

[0118] Next, in step S132, the die-casting control unit 10 operates the hydraulic control circuit 10C to retract the squeeze pin 4. Then, the die-casting control unit 10 moves the squeeze pin 4 to the most retracted state from the dead-end-shaped portion 11F in the cavity 11A, i.e., to the retraction limit state, and blocks communication between the inside of the cavity 11A and the squeeze pin discharge path 71.

[0119] Next, in step S133, oxygen supply control device 40 controls control valve 72V to open external discharge path 74 and chill vent discharge path 72.

[0120] Next, in step S134, hydraulic control circuit 10C is activated to advance the first chill block to the forward position, as shown in Fig. 5. This reduces the flow path cross-sectional area of ​​chill vent discharge passage 72 defined between first chill mold surface 81A and second chill mold surface 82A, and the clearance of chill vent discharge passage 72 is set to the desired setting value.

[0121] Next, when the process proceeds to step S135, as shown in Fig. 1, the die-casting control unit 10 supplies the molten metal A1 from the pouring port 15H into the plunger sleeve 15 using the ladle 15A. At this time, the oxygen supply control device 40 blows a small amount of oxygen into the plunger sleeve 15. This blowing of a small amount of oxygen continues with the oxygen flow rate throttled until the supply of the molten metal A1 is completed, and is stopped when the process proceeds to step S135.

[0122] Next, in step S136, as shown in Fig. 6, the die-casting control unit 10 advances the injection plunger 16 within the plunger sleeve 15 toward the cavity 11A, thereby injecting the molten metal A1 into the cavity 11A. At this time, the molten metal A1 passing through the gate 15G turns into granular droplets, and the droplets are oxidized by oxygen in the cavity 11A, thereby reducing the pressure inside the cavity 11A. As a result, the molten metal A1 filled in the cavity 11A is prevented from containing bubbles that could cause gas voids.

[0123] Next, when the process proceeds to step S137, as shown in Fig. 7, the die-casting control unit 10 operates the hydraulic control circuit 10C to move the squeeze pin 4 forward, and locally pressurizes the molten metal A1 filled in the cavity 11A by the squeeze pin 4. At this time, the squeeze pin 4 particularly pressurizes the dead-end portion 11F in the cavity 11A, which further prevents the molten metal A1 filled in the dead-end portion 11F from entrapping air bubbles.

[0124] In step S137, the squeeze pin 4 is advanced while taking into consideration the progress of solidification of the molten metal A1 filled in the cavity 11A, thereby preventing the molten metal A1 from entering the squeeze pin discharge path 71.

[0125] Next, in step S138, the die-casting control unit 10 operates the hydraulic control circuit 10C to move the first chill block 81 from the forward position to the backward position while the molten metal A1 filled in the cavity 11A is in the middle of solidification and shrinkage, as shown in Fig. 8. This prevents the molten metal A1 from clinging to the first chill mold surface 81A of the first chill block 81.

[0126] In step S138, the first chill block 81 is retracted while taking into consideration the progress of solidification of the molten metal A1 filled in the cavity 11A, thereby preventing the molten metal A1 from clinging to the first chill mold surface 81A.

[0127] First to third cast products B1 to B3 are produced by steps S131 to S138. In this embodiment, for simplicity of explanation, if the oxygen supply control device 40 determines in step S121 that oxygen substitution has been successfully performed in the oxygen substitution step, it also determines that the casting step has been successfully performed. Note that after steps S131 to S138 are performed, a determination can also be made as to whether the casting step was successful.

[0128] Next, in step S141, the oxygen supply control device 40 transmits a non-defective product signal to the product removal device 50, indicating that the first to third cast products B1 to B3 that have been produced are non-defective products. Thereafter, the process proceeds to step S143.

[0129] When the process proceeds from step S121 to step S124, the oxygen supply control device 40 adds the correction value Tcv to the first supply time T1 to eliminate the oxygen substitution defect in the oxygen substitution process, and then proceeds to step S142. As a result, the first supply time T1 is lengthened in the next oxygen substitution process.

[0130] In step S142, the oxygen supply control device 40 determines that if the casting process is performed following the oxygen replacement process in which it has been determined that oxygen replacement was not performed satisfactorily, the resulting first to third cast products B1 to B3 will be defective.The oxygen supply control device 40 then transmits a defective product signal to the product removal device 50 without performing the casting process (steps S131 to S138).Then, the process proceeds to step S143.

[0131] When the process proceeds from step S141 or step S142 to step S143, as shown in Fig. 9, the die-casting control unit 10 controls the mold clamping device (not shown) to open the fixed mold 12 and the movable mold 13. If a non-defective product signal is transmitted to the product removal device 50 in step S141, the die-casting control unit 10 causes the ejector pin 13B to protrude into the cavity 11A to demold the first to third cast products B1 to B3. The product removal device 50 removes the demolded first to third cast products B1 to B3 and transfers them to a non-defective product storage area based on the received non-defective product signal. On the other hand, if a defective product signal is transmitted to the product removal device 50 in step S142, the ejector pin 13B and the product removal device 50 do not operate.

[0132] When the mold 11 is opened in step S143, the first chill block 81 is in the retracted position. That is, the tip of the immovable mold release pin 83 provided on the fixed mold 12 protrudes a predetermined amount in the mold clamping direction from the first chill mold surface 81A. Therefore, the mold release pin 83 can prevent the aluminum solidified material C from sticking to the first chill mold surface 81A.

[0133] Here, the mold 11 may be opened in step S143 with the first chill block 81 in the advanced position without moving the first chill block 81 to the retracted position in step S138. Alternatively, the first chill block 81 may be moved to the retracted position in step S138 to prevent the molten metal A1 from clinging to the first chill mold surface 81A, and then the first chill block 81 may be moved to the advanced position, and the mold 11 may be opened in step S143 with the first chill block 81 in the advanced position. In these cases, after the mold 11 is opened, the first chill block 81 in the advanced position may be retracted to the retracted position, whereby the aluminum solidified material C on the first chill mold surface 81A can be removed by the mold release pin 83 that protrudes from the first chill mold surface 81A as the first chill block 81 retracts.

[0134] Next, when the process proceeds to step S144, as shown in Fig. 10, the die-casting control unit 10 activates the air supply device 90 to blow air onto the tapered inner surface 17A and the tapered outer surface 81B from the air outlet 92. This makes it possible to blow away burrs D on the tapered inner surface 17A and the tapered outer surface 81B with the air, thereby making it possible to prevent the burrs D from getting caught in the tapered inner surface 17A and the tapered outer surface 81B.

[0135] Here, in step S144, the first chill block 81 may be moved back and forth while air is being blown onto the tapered inner surface 17A and the tapered outer surface 81B. This makes it easy to blow away burrs D on the sliding surface between the tapered inner surface 17A and the tapered outer surface 81B with air, and also makes it possible to push out and remove solidified aluminum C remaining on the first chill mold surface 81A with the release pin 83.

[0136] Next, in step S145, the die-casting control unit 10 determines whether or not to repeat the casting. If "Yes" in step S145, the process returns to step S102. On the other hand, if "No" in step S144, the manufacturing process of the casting B is terminated.

[0137] In the die-casting apparatus 1 and the method for manufacturing the casting B of the embodiment, the mold 11 is clamped and the first chill block 81 is in the advanced position, i.e., the chill vent discharge passage 72 defined between the first chill mold surface 81A and the second chill mold surface 82A is set to a desired clearance, and the molten metal A1 is filled into the cavity 11A, thereby suitably preventing the molten metal A1 from leaking out through the chill vent discharge passage 72. Furthermore, if oxygen replacement is performed in the cavity 11A when the mold 11 is clamped and the first chill block 81 is in the retracted position, i.e., when the flow path cross-sectional area of ​​the chill vent discharge passage 72 is expanded, even if solidified aluminum C remains stuck to the chill vent discharge passage 72, it is possible to prevent insufficient gas removal from the chill vent discharge passage and prevent insufficient oxygen replacement in the cavity 11A.

[0138] Furthermore, in the die-casting apparatus 1 and the manufacturing method of the casting B according to the embodiment, the first chill block 81 is moved from the advanced position to the retracted position while the molten metal A1 filled in the cavity 11A is in the middle of solidification and shrinkage, thereby preventing the semi-solidified molten metal A1 from sticking to the first chill mold surface 81A. As the first chill block 81 retracts, the release pins 83 protrude from the first chill mold surface 81A, allowing the semi-solidified molten metal A1 to be peeled off from the first chill mold surface 81A by the release pins 83. Furthermore, in the casting process, if the first chill block 81 is not retracted but the mold 11 is opened with the first chill block 81 in the advanced position, by moving the first chill block 81 from the advanced position to the retracted position after mold opening, the aluminum solidified material C can be removed from the first chill mold surface 81A by the release pins 83 protruding from the first chill mold surface 81A as the first chill block 81 retracts. This further prevents the aluminum solidified material C from clinging to the first chill mold surface 81A, thereby more reliably preventing insufficient gas removal from the chill vent discharge path 72 and insufficient oxygen replacement in the cavity 11A.

[0139] Therefore, the die-casting apparatus 1 and the method for manufacturing the casting B of the embodiment can suppress the occurrence of gas porosity in the casting B.

[0140] Furthermore, in the die-casting apparatus 1 and the manufacturing method for casting B of the embodiment, the sliding surface of the first chill block 81 when it moves forward and backward relative to the fixed mold 12 is a predetermined tapered surface. Therefore, even if burrs D are attached to the sliding surface, the first chill block 81 can easily come out of the accommodation hole 17 when it moves backward. As a result, malfunction of the first chill block 81 due to burrs D getting caught can be suppressed.

[0141] Furthermore, in the die-casting apparatus 1 and the manufacturing method of the casting product B of the embodiment, after the casting process is completed, the mold 11 is opened and the first chill block 81 is in the retracted position, or while the first chill block 81 is being moved back and forth, air is blown from the air supply device 90 onto the tapered inner side surface 17A and the tapered outer side surface 81B, thereby blowing away burrs D on the sliding surface between the tapered inner side surface 17A and the tapered outer side surface 81B with the air, and preventing burrs D from getting caught in the sliding surface. Therefore, malfunction of the first chill block 81 due to burrs D getting caught can be further prevented.

[0142] Furthermore, in the die-casting apparatus 1 and the method for manufacturing cast product B of the embodiment, in the oxygen substitution step (steps S111 to S116), first, a squeeze pin discharge step is carried out in which gas inside cavity 11A is discharged via squeeze pin discharge path 71 while chill vent discharge path 72 is blocked by control valve 72V. As a result, gas inside cavity 11A, particularly in dead-end-shaped portion 11F where gas is likely to stagnate, is discharged via squeeze pin discharge path 71 to squeeze pin connecting discharge path 73. Then, chill vent discharge path 72 is subsequently opened by control valve 72V, and gas inside cavity 11A is discharged to the outside of mold 11 via chill vent discharge path 72 in addition to squeeze pin discharge path 71 and squeeze pin connecting discharge path 73. In this way, in the squeeze pin discharge step, the portion of cavity 11A where gas is likely to stagnate, i.e., dead-end-shaped portion 11F, can be further replaced with oxygen.

[0143] As described above, in the die-casting apparatus 1 and the method for manufacturing the casting B according to the embodiment, the squeeze pin discharge step effectively discharges gas from the cavity 11A, improving oxygen replacement efficiency. As a result, even when casting multiple first to third castings B1 to B3, gas can be discharged through a single chill vent discharge path 72 in the chill vent discharge step, thereby enabling a compact and simplified apparatus structure. However, in this case, if aluminum solidified material C remains stuck to the single chill vent discharge path 72, this can be a direct cause of insufficient oxygen replacement. In this regard, the die-casting apparatus 1 and the method for manufacturing the casting B can address the problem of aluminum solidified material C sticking to the chill vent discharge path 72, thereby enabling a compact and simplified apparatus structure while achieving optimal oxygen replacement through the single chill vent discharge path 72.

[0144] Although the present invention has been described above with reference to the examples, it goes without saying that the present invention is not limited to the above examples and can be modified and applied as appropriate within the scope of the invention.

[0145] In the embodiment, when the mold 11 is clamped, the first chill block 81 provided on the fixed mold 12 can be moved back and forth in the mold clamping direction relative to the second chill block 82 provided on the movable mold 13, but the present invention is not limited to this, and when the mold 11 is clamped, the second chill block 82 provided on the movable mold 13 can also be moved back and forth in the mold clamping direction relative to the first chill block 81 provided on the fixed mold 12.

[0146] In the embodiment, the die-casting apparatus 1 is equipped with a squeeze pin 4, and the molten metal A1 filled in the cavity 11A is locally pressurized by the squeeze pin 4 to produce a pressure-cast product, but the present invention is not limited to this, and a cast product may be produced without locally pressurizing using a die-casting apparatus that does not have a squeeze pin 4.

[0147] In the embodiment, in the squeeze pin discharge step in which gas is discharged from cavity 11A via squeeze pin discharge path 71, chill vent discharge path 72 is closed by control valve 72V until first supply time T1 has elapsed, and then, after first supply time T1 has elapsed, chill vent discharge path 72 is opened by control valve 72V until the end of the oxygen substitution step, but this is not limited to this. For example, chill vent discharge path 72 may be opened by control valve 72V in the first half of the oxygen substitution step and closed by control valve 72V in the second half of the oxygen substitution step. Also, chill vent discharge path 72 may be temporarily closed by control valve 72V during the oxygen substitution step. Furthermore, a configuration in which chill vent discharge path 72 is always open without control valve 72V is also included in the present invention.

[0148] In the embodiment, the squeeze pin discharge step of discharging gas from cavity 11A via squeeze pin discharge path 71 is performed from the start to the end of the oxygen replacement step (steps S111 to S116), but is not limited to this. For example, after performing the squeeze pin discharge step via squeeze pin discharge path 71 in the first half of the oxygen replacement step, the squeeze pin 4 may be moved to its rear limit, and then a chill vent discharge step of discharging gas from cavity 11A to the outside of mold 11 only via chill vent discharge path 72 may be performed in the second half of the oxygen replacement step. Alternatively, the oxygen replacement step may be started with the squeeze pin 4 moved to its rear limit, and after performing the chill vent discharge step of discharging gas from cavity 11A to the outside of mold 11 only via chill vent discharge path 72 in the first half of the oxygen replacement step, the squeeze pin 4 may be moved to its forward limit, and then a squeeze pin discharge step of discharging gas from cavity 11A via squeeze pin discharge path 71 may be performed in the second half of the oxygen replacement step.

[0149] In the embodiment, a die-casting apparatus 1 for casting first to third castings B1 to B3 and a manufacturing method for casting B are described, but the present invention is not limited to this, and the number of castings cast by the die-casting apparatus of the present invention may be one, or multiple castings such as two, four, or more.

[0150] In the embodiment, a die-casting apparatus 1 having one chill vent 80 will be described, but the present invention is not limited to this, and the die-casting apparatus may have two or more chill vents 80. Furthermore, the chill vent 80 may be provided with a cooling mechanism using cooling water or the like.

[0151] The following technical ideas can be extracted from the disclosure of the specification, drawings, etc.

[0152] (Appendix 1) A die-casting apparatus that supplies oxygen into a cavity of a mold and discharges gas in the cavity to the outside via an exhaust path including a chill vent exhaust path, thereby replacing the atmosphere in the cavity with oxygen, and fills the cavity with molten metal to manufacture a casting, The mold includes a fixed mold having a fixed mold surface and a movable mold having a movable mold surface and movable toward and away from the fixed mold in a mold clamping direction, the fixed mold is provided with a first chill block having a first chill mold surface; the movable mold is provided with a second chill block having a second chill mold surface; When the mold is clamped, the cavity is defined between the fixed mold surface and the movable mold surface, and the chill vent discharge path communicating with the cavity is defined between the first chill mold surface and the second chill mold surface, A die-casting apparatus characterized in that, when the mold is clamped, one of the first chill block and the second chill block is movable back and forth in the clamping direction relative to the other.

[0153] (Appendix 2) The fixed mold is provided with a stationary release pin, the first chill block is supported by the fixed mold so as to be movable back and forth in the mold clamping direction, The first chill block has an insertion hole that opens to the first chill mold surface and with which the release pin slides, When the first chill block is at an advanced position advanced in the mold clamping direction, a tip surface of the release pin inserted into the insertion hole forms a part of the first chill mold surface, 2. The die-casting apparatus according to claim 1, wherein the tip of the mold release pin protrudes from the first chill mold surface when the first chill block is in a retracted position retracted in the mold clamping direction.

[0154] (Appendix 3) the fixed mold has a receiving hole that opens to the fixed mold surface, the first chill block is accommodated in the accommodation hole and supported by the fixed mold so as to be movable back and forth in the mold clamping direction; The receiving hole has a tapered inner side surface that extends while gradually widening the distance therebetween as it moves away from the fixed mold surface in the mold clamping direction, 3. The die-casting apparatus according to claim 1, wherein the first chill block has a tapered outer surface that is in sliding contact with the tapered inner surface when the first chill block moves back and forth in the mold clamping direction.

[0155] (Appendix 4) 4. The die-casting apparatus according to claim 3, further comprising an air injection device that blows air onto the tapered inner surface and the tapered outer surface.

[0156] (Appendix 5) a squeeze pin that locally applies pressure to the molten metal filled in the cavity; the discharge path includes a squeeze pin discharge path formed in the squeeze pin, 5. The die-casting apparatus according to any one of appendixes 1 to 4, wherein the squeeze pin discharge path is in communication with the inside of the cavity when the squeeze pin has advanced into the cavity, thereby discharging gas from the cavity, and is in communication with the inside of the cavity when the squeeze pin has retracted from the cavity.

[0157] (Appendix 6) the exhaust path includes an external exhaust path connected to the chill vent exhaust path; the die-casting machine includes a control valve that can open and close the external discharge path; 6. The die casting apparatus according to claim 5, wherein the control valve blocks the external discharge path when the squeeze pin discharge path communicates with the inside of the cavity.

[0158] (Appendix 7) A method for manufacturing a casting using the die-casting apparatus according to any one of appendices 1 to 6, an oxygen replacement step of replacing the inside of the cavity with oxygen by supplying oxygen into the cavity of the mold and discharging the gas inside the cavity to the outside through the exhaust path including the chill vent exhaust path; a casting step of filling the cavity with the molten metal to produce the casting, the oxygen replacement step includes a chill vent discharge step of discharging gas from the cavity through the chill vent discharge path while the mold is clamped and one of the first chill block and the second chill block is in a retracted position retracted in the mold clamping direction relative to the other chill block, The casting process is characterized by including a molten metal filling process of filling the cavity with molten metal while the mold is clamped and one of the first chill block and the second chill block is in an advanced position advanced in the mold clamping direction relative to the other.

[0159] (Appendix 8) 8. The method for manufacturing a casting according to claim 7, wherein in the molten metal filling step, one of the first chill block and the second chill block, which is in the forward position, is retracted toward the retracted position while the molten metal filled in the cavity is in the middle of solidification shrinkage as it begins to solidify.

[0160] (Appendix 9) the die-casting machine includes a squeeze pin that locally applies pressure to the molten metal filled in the cavity, the discharge path includes a squeeze pin discharge path formed in the squeeze pin, 9. The method for manufacturing a casting according to claim 7 or 8, wherein the oxygen replacement step includes a squeeze pin discharge step of communicating the squeeze pin discharge path with the inside of the cavity in a state where the squeeze pin has advanced into the cavity, and discharging gas inside the cavity via the squeeze pin discharge path.

[0161] (Appendix 10) the exhaust path includes an external exhaust path connected to the chill vent exhaust path; 10. The method for producing a casting according to claim 9, wherein the squeeze pin discharge step blocks the external discharge path. [Industrial Applicability]

[0162] The present invention is applicable to die casting equipment and castings. [Explanation of symbols]

[0163] 1...Die-casting equipment 4...Squeeze pin 11...Mold 11A...cavity 12…Fixed type 12A…Fixed type surface 13…Movable type 13A…Movable surface 17...Housing hole 17A...Tapered inner surface 71...Squeeze pin discharge path (discharge path) 72... Chill vent exhaust (exhaust route) 72V...Control valve 73...Squeeze pin connection discharge path (discharge path) 74...External exhaust path (exhaust path) 81...1st Chill Block 81A...First chill type surface 81B...Tapered outer surface 81C...Through hole 82...Second Chill Block 82A...Second chill type surface 83...Release pin 90...Air supply device (air injection device) 91...Air passage (air injection device) 92...Air outlet (air injection device) A1...molten metal B1...First casting (casting) B2: Second casting (casting) B3: Third casting (casting) S111 to S116: Oxygen substitution process S131~S138...Casting process

Claims

1. A die-casting apparatus that supplies oxygen into a cavity of a mold and discharges gas in the cavity to the outside via an exhaust path including a chill vent exhaust path, thereby replacing the atmosphere in the cavity with oxygen, and fills the cavity with molten metal to manufacture a casting, The mold includes a fixed mold having a fixed mold surface and a movable mold having a movable mold surface and movable toward and away from the fixed mold in a mold clamping direction, the fixed mold is provided with a first chill block having a first chill mold surface; the movable mold is provided with a second chill block having a second chill mold surface; When the mold is clamped, the cavity is defined between the fixed mold surface and the movable mold surface, and the chill vent discharge path communicating with the cavity is defined between the first chill mold surface and the second chill mold surface, A die-casting apparatus characterized in that, when the mold is clamped, one of the first chill block and the second chill block is movable back and forth in the clamping direction relative to the other.

2. The fixed mold is provided with a stationary release pin, the first chill block is supported by the fixed mold so as to be movable back and forth in the mold clamping direction, The first chill block has an insertion hole that opens to the first chill mold surface and into which the release pin slides, When the first chill block is at an advanced position advanced in the mold clamping direction, a tip surface of the release pin inserted into the insertion hole forms a part of the first chill mold surface, The die casting apparatus according to claim 1 , wherein a tip of the mold release pin protrudes from the first chill mold surface when the first chill block is in a retracted position retracted in the mold clamping direction.

3. the fixed mold has a receiving hole that opens to the fixed mold surface, the first chill block is accommodated in the accommodation hole and supported by the fixed mold so as to be movable back and forth in the mold clamping direction; The receiving hole has a tapered inner side surface that extends while gradually widening the distance therebetween as it moves away from the fixed mold surface in the mold clamping direction, 2. The die casting apparatus according to claim 1, wherein the first chill block has a tapered outer surface that is in sliding contact with the tapered inner surface when the first chill block moves back and forth in the mold clamping direction.

4. 4. The die casting machine according to claim 3, further comprising an air injection device for blowing air onto the tapered inner surface and the tapered outer surface.

5. a squeeze pin that locally applies pressure to the molten metal filled in the cavity; the discharge path includes a squeeze pin discharge path formed in the squeeze pin, 5. The die casting apparatus according to claim 1, wherein the squeeze pin discharge path is in communication with the interior of the cavity when the squeeze pin has advanced into the cavity, thereby discharging gas from the cavity, and is closed off from the interior of the cavity when the squeeze pin has retracted from the cavity.

6. the exhaust path includes an external exhaust path connected to the chill vent exhaust path; the die-casting machine includes a control valve that can open and close the external discharge path; 6. The die casting apparatus according to claim 5, wherein the control valve blocks the external discharge path when the squeeze pin discharge path communicates with the inside of the cavity.

7. A method for manufacturing a casting using the die-casting apparatus according to any one of claims 1 to 4, an oxygen replacement step of replacing the inside of the cavity with oxygen by supplying oxygen into the cavity of the mold and discharging the gas inside the cavity to the outside through the exhaust path including the chill vent exhaust path; a casting step of filling the cavity with the molten metal to produce the casting, the oxygen replacement step includes a chill vent discharge step of discharging gas from the cavity through the chill vent discharge path while the mold is clamped and one of the first chill block and the second chill block is in a retracted position retracted in the mold clamping direction relative to the other chill block, The casting process is characterized by including a molten metal filling process in which molten metal is filled into the cavity while the mold is clamped and one of the first chill block and the second chill block is in an advanced position advanced in the mold clamping direction relative to the other.

8. 8. The method for manufacturing a casting according to claim 7, wherein in the molten metal filling step, one of the first chill block and the second chill block, which is in the forward position, is retracted toward the retracted position while the molten metal filled in the cavity is in the middle of solidification shrinkage as it begins to solidify.

9. the die-casting machine includes a squeeze pin that locally pressurizes the molten metal filled in the cavity, the discharge path includes a squeeze pin discharge path formed in the squeeze pin, 8. The method for manufacturing a casting according to claim 7, wherein the oxygen substitution step includes a squeeze pin discharge step of communicating the squeeze pin discharge path with the inside of the cavity in a state where the squeeze pin has advanced into the cavity, and discharging gas inside the cavity through the squeeze pin discharge path.

10. the exhaust path includes an external exhaust path connected to the chill vent exhaust path; The method for manufacturing a casting according to claim 9, wherein the squeeze pin discharge step includes blocking the external discharge path.

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