JP2007203361A - Casting method and casting equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a casting method and casting equipment which can securely actuate a molten metal sensor while assuring the depressurizing efficiency of a cavity. <P>SOLUTION: The casting equipment includes a depressurizing passage cross-sectional area adjusting unit 20 which performs a changeover of increasing or decreasing the cross-sectional area of a portion of the depressurizing passage 15 depending on the prescribed timing of casting, the portion being faced by the molten metal sensor 19. During an initial casting period, molten metal is poured at a low speed, with the cross-sectional area of the portion of the depressurizing passage increased. Then, as a changeover is made from low-speed pouring to high-speed pouring, the cross-sectional area of the portion is changed over from the increased state to the decreased state. During a final casting period, the molten metal is poured at a high speed, with the cross-sectional area of the portion decreased. Accordingly, during the initial casting period the molten metal is poured at the low speed, with the cross-sectional area of the portion of the depressurizing passage 15 increased, evacuating efficiency in the depressurizing passage 15 is enhanced when the cavity 8 is depressurized, whereby the depressurizing efficiency of the cavity 8 is enhanced. During the final casting period the molten metal is poured at the high speed, with the cross-sectional area of the portion of the depressurizing passage 15 decreased so that the molten metal is securely sensed by the molten metal sensor 19. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting method and a casting apparatus, and more particularly to a casting method and a casting apparatus in which a cavity of a casting mold is decompressed by a decompression device.

A casting apparatus using a casting mold is known in which molten metal (molten metal) is supplied to a cavity decompressed by a decompression device (see, for example, Patent Document 1). In this type of casting apparatus, the gas in which the air in the cavity, the release agent or the like is vaporized is exhausted from the cavity, and the casting failure of the product due to the inclusion of these gases in the molten metal is prevented. By the way, in this type of casting apparatus, a decompression valve is provided in a decompression path that communicates the decompression apparatus and the cavity, and the melt detection signal of the melt detection sensor provided facing the decompression path on the cavity side from the decompression valve On the basis of this, the pressure reducing valve is closed, and this makes it possible to continue the pressure reduction of the cavity until immediately before the final filling of the melt. However, in this type of casting apparatus, it is necessary to narrow the cross-sectional area in the vicinity of the molten metal detection sensor in the decompression path so that the molten metal detection sensor can reliably detect the molten metal. For this reason, in the conventional casting apparatus, the exhaust gas resistance during the decompression of the cavity is increased, the decompression efficiency of the cavity is lowered, and the ultimate ultimate decompression degree (vacuum degree) cannot be increased, and the expected cast hole The reduction effect cannot be obtained. In particular, the greater the casting weight, the shorter the injection speed and the shorter the pressure reduction time, so it is more difficult to increase the final ultimate pressure reduction degree (vacuum degree).
JP 2004-337932 A

Accordingly, the present invention has been made in view of the above circumstances, and a first object is to provide a casting method capable of reliably operating a molten metal detection sensor while ensuring the pressure reduction efficiency of a cavity. .
A second object is to provide a casting apparatus capable of reliably operating a molten metal detection sensor while ensuring the decompression efficiency of the cavity.

In order to achieve the first object, according to the first aspect of the present invention, the cavity of the casting mold is decompressed by the decompression device, and the melt detection sensor detects the melt flowing down the decompression path. The pressure reducing valve is closed in the casting method, wherein the cross-sectional area of the portion of the pressure reducing path facing the molten metal detection sensor is switched between an enlarged state and a reduced state at a predetermined casting timing.
According to a second aspect of the present invention, in the casting method according to the first aspect, at the initial stage of casting, the cross-sectional area of the portion of the decompression path facing the molten metal detection sensor is enlarged, and casting is performed. The cross-sectional area of the decompression path is switched to a reduced state at the timing of switching from the initial stage to the end of casting.
The invention according to claim 3 is the casting method according to claim 1 or 2, wherein, at the time of low speed filling, the cross-sectional area of the portion of the decompression path facing the molten metal detection sensor is enlarged, and casting is performed. The cross-sectional area of the decompression path is switched to a reduced state at the timing of switching from low speed filling to high speed filling.

In order to achieve the second object, the invention according to claim 4 of the present invention is such that the cavity of the casting mold is decompressed by the decompression device, and the melt detection sensor detects the melt flowing down the decompression path. The pressure reducing valve is closed, and the pressure reducing passage cross-sectional area variable device is provided, wherein the cross sectional area of the portion of the pressure reducing passage facing the molten metal detection sensor is switched between an enlarged state and a reduced state at a predetermined casting timing. It is characterized by doing.
According to a fifth aspect of the present invention, in the casting apparatus according to the fourth aspect of the present invention, the depressurization path cross-sectional area variable device is provided so as to be able to project and retract with respect to the depressurization path, and faces the molten metal detection sensor across the depressurization path. And a drive unit that drives the valve body to project / retract from the decompression path, and a control unit that controls the operation of the drive unit.
A sixth aspect of the present invention is the casting apparatus according to the fourth or fifth aspect, further comprising a plunger position detection sensor for detecting a plunger position of the injection device, wherein the pressure reducing path cross-sectional area varying device is detected by the plunger position detection sensor. The control unit controls the operation of the driving unit based on the signal.

Therefore, in the first aspect of the present invention, the cross-sectional area of the portion of the decompression path that the molten metal detection sensor faces is switched between the enlarged state and the reduced state at a predetermined casting timing.
In the invention according to claim 2, casting is performed in an enlarged state in a cross-sectional area of a portion of the decompression path facing the molten metal detection sensor at an initial stage of casting, and at a final stage of casting, the molten metal detection sensor is disposed in the decompression path. Casting is performed with the cross-sectional area of the facing portion being reduced.
According to the third aspect of the present invention, casting is performed in a state where the cross-sectional area of the portion of the decompression path facing the molten metal detection sensor is enlarged during low speed filling, and the molten metal detection sensor of the decompression path faces during high speed filling. Casting is performed with the cross-sectional area of the portion being reduced.

In the invention according to claim 4, the sectional area of the portion of the decompression path facing the molten metal detection sensor is switched between the expanded state and the contracted state by the decompression path variable area device.
According to a fifth aspect of the present invention, the depressurization path cross-sectional area varying device drives the drive unit under the control of the control unit to project / retreat the valve body with respect to the depressurization path, thereby detecting the molten metal detection sensor in the depressurization path. Reduce / enlarge the cross-sectional area of the part facing the.
In the invention according to claim 6, in the depressurization path cross-sectional area varying device, the control unit controls the operation of the drive unit based on the detection signal of the plunger position detection sensor, so that the valve body protrudes from the depressurization path. Evacuated.

  It is possible to provide a casting method and a casting apparatus capable of reliably operating the molten metal detection sensor while ensuring the decompression efficiency of the cavity.

  An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the present casting apparatus 1 includes a casting mold 4 including a fixed mold 2 and a movable mold 3, and the fixed mold 2 and the movable mold 3 are respectively connected to a fixed platen 5 and a movable platen 6. Fixed. Further, in the present casting apparatus 1, the movable platen 6 is guided by a plurality of (four in the present embodiment) tie bars 7 having one end fixed to the fixed platen 5, and the mold opening / closing direction (left-right direction in FIG. 1). Moved to. Then, the movable platen 6 is moved in the mold closing direction (rightward in FIG. 1) by driving the mold opening / closing mechanism, and the fixed mold 2 and the movable mold 3 are coupled to each other, so that the fixed mold 2 and the movable mold 3 are connected. The cavity 8 is formed in the (casting mold 4). The casting apparatus 1 includes a sleeve 9 attached to the stationary platen 5, and a plunger 11 from which molten metal (molten metal) injected into the sleeve 9 from the molten metal inlet 10 of the sleeve 9 is injected toward the cavity 8. The injection device 12 is provided.

  Further, as shown in FIG. 1, the casting apparatus 1 includes a decompression device 13 that evacuates the cavity 8 to decompress the cavity 8. The decompression device 13 is configured by connecting a vacuum tank 14 decompressed by a vacuum pump and a decompression path 15 formed in the casting mold 4 and communicating with the cavity 8 by a decompression hose 16. The casting apparatus 1 is provided with a pressure reducing valve 17 in the pressure reducing path 15, and the opening / closing operation of the pressure reducing valve 17 is controlled by a control device 18 (control unit) constituted by a microcomputer. Is structured to be opened and closed. Further, the casting apparatus 1 includes a molten metal detection sensor 19 which is embedded in the fixed mold 2 and whose detection portion faces a portion closer to the cavity 8 than the pressure reducing valve 17 of the pressure reducing path 15. In the casting apparatus 1, when the molten metal flowing down the pressure reducing path 15 is detected by the molten metal detection sensor 19, the pressure reducing valve 17 is closed by the control device 18, and the molten metal is prevented from entering the pressure reducing valve 17. It has become a structure.

  Further, as shown in FIG. 1, the present casting apparatus 1 includes a pressure reducing path cross-sectional area variable device 20 that is provided on the movable mold 3 and is disposed to face the molten metal detection sensor 19 across the pressure reducing path 15. . As shown in FIGS. 2 and 3, the pressure reducing path cross-sectional area varying device 20 is accommodated in an accommodating portion 21 formed in the movable die 3, and a valve body 23 formed in a truncated cone shape is accommodated in the accommodating portion. 21 is formed in a partition wall 22 between the pressure reducing path 15 and is engaged with a tapered hole 24 whose inner diameter is reduced from the accommodating portion 21 toward the pressure reducing path 15. In the casting apparatus 1, the taper angle of the taper hole 24 is 5. And an inclination angle with respect to the center line of the bus bar of the valve body 23 is also 5. Set to The pressure reducing path cross-sectional area varying device 20 includes a hydraulic cylinder 25 (driving unit) that moves the valve body 23 in the approaching / separating direction (left-right direction in FIG. 2) with respect to the molten metal detection sensor 19. Is attached to a lid member 26 fixed to the partition wall 22 via a spacer 27.

  In the casting apparatus 1, the control device 18 controls the operation of the hydraulic cylinder 25, so that the valve body 23 is driven and protrudes / retreats with respect to the decompression path 15. As a result, the portion of the decompression path 15 facing the molten metal detection sensor 19, more specifically, the portion of the decompression path 15 between the detection surface 19 a of the molten metal detection sensor 19 and the end surface 23 a of the valve body 23 is broken. The area is expanded (the valve body 23 is retracted from the decompression path 15, see FIG. 2) and the contracted state (the valve body 23 protrudes from the decompression path 15 and the cross-sectional area is expanded) 50% of the state (see FIG. 3)). As shown in FIGS. 2 and 3, the variable pressure passage cross-sectional area changing device 20 has a 0-ring 28 provided on the mounting surface 26a of the lid member 26 in contact with the partition wall 22 and a piston rod insertion hole 26b. The 0-ring 29 provided on the piston member 25a is slidably contacted with the piston rod 25a, whereby the inner space (decompression passage 15) and the outer space (accommodating portion 21) of the lid member 26 are separated from each other while ensuring airtightness. ing.

  The casting apparatus 1 also includes a plunger position detection sensor that detects a magnet embedded in the plunger 11 and detects the position of the plunger 11. In the casting apparatus 1, in the initial casting stage (during low-speed filling where the plunger 11 is driven at a low speed), as shown in FIG. 2, the decompression path cross-sectional area varying device 20 retracts the valve body 23. Is in a state. When the plunger 11 reaches a position 40 mm before the casting timing at which the low-speed filling is switched to the high-speed filling, the plunger 11 is detected by the plunger position detection sensor, thereby reducing the pressure as shown in FIG. The variable road cross-sectional area device 20 projects the valve body 23, and the cross-sectional area of the portion between the detection surface 19a of the molten metal detection sensor 19 and the end surface 23a of the valve body 23 in the decompression path 15 is reduced from the expanded state. In this state, filling is performed at the end of casting (at the time of high speed filling in which the plunger 11 is driven at high speed).

  Next, the present casting method will be described. First, as shown in FIG. 1, the fixed mold 2 and the movable mold 3 are combined to close the casting mold 4, and the cavity 8 is formed inside the casting mold 4. Next, molten metal (molten metal) is injected from the molten metal injection port 10 into the sleeve 9 of the injection device 12. At this time, the plunger 11 is positioned at the initial position where the molten metal inlet 10 of the sleeve 9 is opened. In this state, the pressure reducing valve 17 is closed, and the vacuum degree of the vacuum tank 14 is increased toward the pressure reduction of the cavity 8. Further, the valve body 23 of the decompression path cross-sectional area varying device 20 is in a retracted state with respect to the decompression path 15 shown in FIG. 2, and the cross-sectional area of the portion of the decompression path 15 facing the molten metal detection sensor 19 is It is in a state (enlarged state) equal to the cross-sectional area of the other part of the decompression path 15. After the molten metal injection is completed, the plunger 11 of the injection device 12 is driven to the forward side (right side in FIG. 1) at a low speed, and the pressure reducing valve 17 is opened when the molten metal inlet 10 of the sleeve 9 is closed by the plunger 11. It is. As a result, the cavity 8 is rapidly decompressed while the low-speed filling (initial casting) is continued.

  Next, when it is detected by the plunger position detection sensor that the plunger 11 has reached a position 40 mm before the casting timing at which the low-speed filling is switched to the high-speed filling, the pressure reducing path cross-sectional area is variable from the control device 18 (control unit). A pressure reducing path cross-sectional area switching signal is output to the device 20, and the pressure reducing path cross-sectional area changing device 20 moves the valve body 23 toward the pressure reducing path 15 as shown in FIG. Make it protrude. As a result, the cross-sectional area of the portion of the decompression path 15 facing the molten metal detection sensor 19 is reduced to 50% of the enlarged state and is in the reduced state. Then, the speed (filling speed) of the plunger 11 is switched to a high speed, and during the high speed filling (end of casting), the molten metal detecting sensor 19 detects the molten metal flowing down the pressure reducing path 15 from the cavity 8 toward the pressure reducing valve 17. Then, a valve closing operation signal is output from the control device 18 to the pressure reducing valve 17, thereby closing the pressure reducing valve 17.

This embodiment has the following effects.
The casting apparatus 1 includes a pressure reducing path cross-sectional area variable device 20 that switches a cross-sectional area of a portion of the pressure reducing path 15 facing the molten metal detection sensor 19 between an enlarged state and a reduced state at a predetermined casting timing. The cross-sectional area is changed from the enlarged state to the reduced state at the casting timing when the cross-sectional area is expanded and the low-speed filling is performed, and the low-speed filling is switched to the high-speed filling. High speed filling is performed.
Therefore, compared with the conventional casting apparatus 1 in which the cross-sectional area of the portion of the decompression path 15 facing the molten metal detection sensor 19 is fixedly reduced, the present casting apparatus 1 has an initial stage of the decompression path 15. Among them, since the low-speed filling is performed in an enlarged state where the cross-sectional area of the portion facing the molten metal detection sensor 19 is equal to the cross-sectional area of the other portion, the exhaust efficiency in the decompression path 15 when the cavity 8 is decompressed, The decompression efficiency is increased. In addition, at the end of casting, high-speed filling is performed in a reduced state in which the cross-sectional area is reduced to 50% with respect to the initial stage of casting.
This makes it possible to efficiently depressurize the cavity 8 in a short time, and it is possible to obtain a high-quality product with very few cast holes even when casting a casting with a large casting weight. Further, it is possible to reliably prevent the molten metal from entering the pressure reducing valve 17 and improve the reliability of the casting apparatus 1.

In addition, embodiment is not limited above, For example, you may comprise as follows.
In the reduced state, the cross-sectional area of the portion of the decompression path 15 facing the molten metal detection sensor 19 is reduced to 50% with respect to the enlarged state, but the cross-sectional area is reduced to 40% or 60% as necessary. The decompression path cross-sectional area variable device 20 may be configured to be reduced, or the degree of reduction may be variable.
In the present casting apparatus 1, when the plunger 11 of the injection apparatus 12 reaches a position 40 mm before the casting timing at which the low-speed filling is switched to the high-speed filling, the valve body 23 of the decompression path cross-sectional area variable device 20 is driven. The cross-sectional area of the portion of the decompression path 15 facing the molten metal detection sensor 19 is shifted from the enlarged state to the reduced state. The timing of the transition is 30 mm, which is the casting timing at which the plunger 11 is switched from low speed filling to high speed filling. Or it is good also as a time of reaching | attaining the position of 50 mm near.

  Further, as shown in FIG. 4, a decompression path 31 where the molten metal detection sensor 19 is installed (a decompression path 31 where molten metal is detected by the molten metal detection sensor 19), a decompression path 32 where the molten metal detection sensor 19 is not installed, The two decompression paths 31 and 32 are configured in the casting mold 4, and the cavity 8 is decompressed by using both decompression paths 31 and 32 for low-speed filling (filling initial stage), and molten metal is detected for high-speed filling (filling final stage). The casting apparatus 1 may be configured to decompress the cavity 8 using only the decompression path 31 on which the sensor 19 is installed. In this case, at the time of low speed filling, the pressure of the cavity 8 is reduced by using both the pressure reducing paths 31 and 32, and the pressure reducing efficiency of the cavity 8 is increased. At the time of high speed filling, the molten metal detection sensor 19 reliably detects the molten metal. The

  Further, as shown in FIG. 5, one section of the decompression path 15 is divided into a decompression path 15a and a decompression path 15b, a shutoff valve 33 is provided in one decompression path 15a, and the other decompression path 15b is connected to one side. The melt detection sensor 19 is installed with a small cross-sectional area with respect to the decompression path 15a, and for low-speed filling (the initial stage of filling), the shutoff valve 33 is opened and the cavity 8 is used by using both decompression paths 15a and 15b. The casting apparatus 1 is configured so that the cavity 8 is decompressed using only the decompression path 15b on which the molten metal detection sensor 19 is installed by closing the shut-off valve 33 during high-speed filling (end of filling). May be. In this case, at the time of low speed filling, the pressure of the cavity 8 is reduced by using both pressure reducing passages 15a and 15b, and the pressure reduction efficiency of the cavity 8 is increased. At the time of high speed filling, the molten metal detection sensor 19 reliably detects the molten metal. The

It is explanatory drawing of this casting apparatus, and is the front view which showed a part in cross section. It is explanatory drawing of a pressure-reduction-path cross-sectional area variable apparatus, and is a figure which shows an enlarged state especially. It is explanatory drawing of a pressure-reduction-path cross-sectional area variable apparatus, and is a figure which shows a reduction state especially. It is explanatory drawing of other embodiment which has two pressure reduction paths. It is explanatory drawing of other embodiment by which a part of decompression path was divided | segmented.

Explanation of symbols

1 casting device, 4 casting molds, 11 plunger, 12 injection device, 13 pressure reducing device, 15 pressure reducing passage, 17 pressure reducing valve, 18 control device (control unit), 19 molten metal detection sensor, 20 pressure reducing passage cross-sectional area variable device, 23 Valve body, 25 hydraulic cylinder (drive unit)

Claims (6)

  A casting method in which a cavity of a casting mold is decompressed by a decompression device, and a decompression valve is closed by detecting a melt flowing down the decompression path by a melt detection sensor, and the melt detection sensor faces the decompression path. A casting method, wherein the cross-sectional area of the portion is switched between an enlarged state and a reduced state at a predetermined casting timing.   In the initial stage of casting, the cross-sectional area of the portion of the decompression path facing the molten metal detection sensor is expanded and casting is performed, and the cross-sectional area of the decompression path is reduced at the timing of switching from the initial casting stage to the final casting stage. The casting method according to claim 1, wherein the casting method is switched to a state.   During low-speed filling, the cross-sectional area of the decompression path facing the molten metal detection sensor is expanded and casting is performed, and the cross-sectional area of the decompression path is reduced at the timing of switching from low-speed filling to high-speed filling. The casting method according to claim 1, wherein the casting method is switched to.   The casting mold cavity is decompressed by a decompression device, and the melt detection sensor detects the melt flowing down the decompression path, whereby the decompression valve is closed. A casting apparatus comprising: a pressure reducing path cross-sectional area variable device capable of switching a cross-sectional area of a portion to be enlarged and reduced at a predetermined casting timing.   The depressurization path cross-sectional area variable device is provided so as to be able to appear in and out of the depressurization path, and is arranged to face the molten metal detection sensor across the depressurization path, and to drive the valve body to The casting apparatus according to claim 4, further comprising: a drive unit that protrudes / withdraws from the decompression path; and a control unit that controls an operation of the drive unit. A plunger position detection sensor for detecting a plunger position of the injection device is provided, and the pressure reducing path cross-sectional area variable device is configured such that the control unit controls the operation of the drive unit based on a detection signal of the plunger position detection sensor. The casting apparatus according to claim 4 or 5.

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