JPH07232258A - Casting method using electromagnetic pump - Google Patents

Abstract

PURPOSE:To provide a casting method, by which vacuum casting can be executed by forcedly evacuating the air in a cavity of a die, in the casting method supplying molten metal with an EMP device. CONSTITUTION:At the time of supplying the molten metal into an injection cylinder 6 with the electromagnetic pump 4, the cavity 13 of the die is communicated with the atmosphere system 21 to make the inner part of the cavity the atmospheric condition. As the inner part of the injection cylinder communicated with the cavity is made to be the atmospheric condition, too, the air having the vol. of the supplied molten metal is exhausted from the injection cylinder through the cavity accompanied with a supply of molten metal into the cavity. Therefore, the stable molten metal feeding force is displayed by the originality of the electromagnetic pump and the stable molten metal quantity can be supplied. At the time of injecting the molten metal into the cavity 13 with a plunger tip 7, the cavity is communicated with a vacuum evacuating system 22 and the inner part of the cavity is forcedly evacuated to execute the vacuum casting. Therefore, the entrapment of gas into the cast product is restrained to the min. limit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method using an electromagnetic pump.

[0002]

2. Description of the Related Art Casting is carried out by supplying molten metal into an injection cylinder and injecting it into a mold cavity communicating with the injection cylinder by a plunger tip. As a device for supplying hot water to an injection cylinder, a molten metal supply device (hereinafter referred to as “EMP device”) having an electromagnetic pump has been developed. This device is an electromagnetic pump (Elec
tro Magnetic Pump) is used to transfer conductive molten metal and supply it directly to the underside of the injection cylinder. EM
According to the P device, it is not necessary to drop the molten metal into the injection cylinder to supply the molten metal, and thus it is possible to prevent air from being entrained in the molten metal. Further, since the injection operation can be performed immediately after the hot water supply is completed, it is possible to suppress the generation of the solidified layer.

In the casting method, a vacuum casting method has also been developed in which the cavity is forcibly evacuated. According to the vacuum casting method, the gas in the mold cavity can be sufficiently discharged, so that the gas can be prevented from remaining inside the product.

Therefore, if hot water can be supplied to the injection cylinder and the mold cavity can be forcibly exhausted by the EMP apparatus, entrainment of gas into the product can be significantly reduced and a high quality product can be manufactured.

[0005]

However, when the molten metal is pressure-fed by the electromagnetic pump to the injection cylinder communicating with the mold cavity while the mold cavity is forcibly evacuated, the power output and vacuum of the electromagnetic pump are reduced. Together with the pulling, it acts on the molten metal, making it impossible to supply a stable amount of molten metal. For this reason, conventionally, it has been impossible to combine hot water supply by the EMP apparatus and vacuum casting.

The present invention has been made in order to solve the above problems, and an object thereof is a casting method for supplying hot water by an EMP apparatus, in which the inside of a mold cavity is forcibly evacuated to perform vacuum casting. It is to provide a casting method that can be performed.

[0007]

In order to achieve the above object, the present invention injects a molten metal supplied into an injection cylinder by an electromagnetic pump into a mold cavity connected to the injection cylinder by a plunger tip. In a casting method using an electromagnetic pump, when the molten metal is supplied into the injection cylinder (6) by the electromagnetic pump (4), the mold cavity (13) is communicated with an atmosphere system (21) and the plunger tip Mold cavity (13) according to (7)
Provided is a casting method using an electromagnetic pump, which is characterized in that, when the molten metal is injected into the inside, the die cavity (13) is communicated with a vacuum exhaust system (22) to perform vacuum casting.

[0008]

According to the casting method having the above steps, the atmosphere system and the vacuum exhaust system are switched between the hot water supply step to the injection cylinder and the injection step into the mold cavity. In the hot water supply process, the mold cavity is open to the atmosphere,
The inside of the injection cylinder communicating with the mold cavity is also open to the atmosphere. In such a state where the atmosphere is open, as the volume of molten metal that has been supplied is discharged from the injection cylinder through the mold cavity as the hot water is supplied into the injection cylinder, the stable molten metal feed output of the electromagnetic pump is maintained. It is demonstrated, and it becomes possible to supply a stable amount of hot water. On the other hand, in the injection step, since the inside of the mold cavity is forcibly evacuated, it is possible to minimize the entrainment of gas into the cast product when the molten metal is injected into the mold cavity.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a casting apparatus for carrying out the casting method of the embodiment of the present invention will be described with reference to FIGS.

The casting apparatus 1 of this embodiment comprises an EMP apparatus 2. The EMP device 2 has a holding furnace 3 in which the molten metal M is stored.
And a hot water supply path 5 whose one end is connected to the holding furnace 3, and an electromagnetic pump 4 provided around the hot water supply path 5. The other end of the hot water supply path 5 is connected to the bottom of the injection cylinder 6. When the electromagnetic pump 4 operates, the molten metal M having conductivity is transferred through the hot water supply path 5 and supplied into the injection cylinder 6. By operating the electromagnetic pump 4 for a predetermined time and transferring the melt for the predetermined time, a desired amount of the melt can be supplied to the injection cylinder 6.

Inside the injection cylinder 6, there is provided a plunger 8 which is movable in the axial direction thereof. The movement of the plunger 8 causes the plunger tip 7 at the tip thereof to slide in the injection cylinder 6. A limit bar 9 is attached at a predetermined position of the plunger 8. The front end of the injection cylinder 6 has a movable mold 11 and a fixed mold 12.
Is communicated with the cavity 13 formed between. The movable mold 11 is supported by a movable platen 17, and the fixed mold 12 is supported by a fixed platen 18. With the movement of the movable platen 17, the cavity 13 can be opened.

The cavity 13 is formed with a gas vent passage 14 for discharging the gas inside. A molten metal detection sensor 15 for detecting molten metal is arranged in the gas vent passage 14. This molten metal sensor 15
Is provided with an electrode rod that protrudes into the gas vent passage 14 and electrically senses the presence of the molten metal by coming into contact with the conductive molten metal. The gas vent passage 14 is further provided with an exhaust valve mechanism 16 that can be opened and closed, and is selectively connected to the air path 19 via the exhaust valve mechanism 16. Here, specifically, the exhaust valve mechanism 16 includes an operating cylinder 16a, a piston 16c having a valve member 16b, an electromagnetic switching valve 16d, and a compressor 16e, as shown in FIG. The working cylinder 16a is
The piston 16c includes a front chamber 16f and a rear chamber 16g. The compressed air from the compressor 16e is sent to the front chamber 16f or the rear chamber 16g by the operation of the electromagnetic switching valve 16d, so that the piston 1
6c moves to the left and right in FIG. A valve seat 14a is formed in the gas vent passage 14. When the piston 16c moves to the left and the valve member 16b separates from the valve seat 14a, the valve mechanism 16 opens and connects the gas vent passage 14 to the air passage 19. Further, the piston 16c moves to the right to seat the valve member 16b on the valve seat 14a,
The valve mechanism 16 closes to open the gas vent passage 14 and the air passage 1.
Disconnect 9 connection. This valve closing operation prevents the molten metal from entering the air path 19 through the gas vent passage 14.

The air path 19 is switchably connected to an atmosphere path 21 and a vacuum path 22 via an atmosphere / vacuum switching electromagnetic valve 20. The atmosphere path 21 is branched and includes an atmosphere opening solenoid valve 23 and an air blow solenoid valve 24, respectively. The air-releasing electromagnetic valve 23 is open to the atmosphere after the latter, and the air-blowing electromagnetic valve 24 is connected to an air source 25. On the other hand, the vacuum path 22 is provided with a vacuum tank 26 and a vacuum pump 27.

The casting apparatus 1 of this embodiment is further provided with a valve control unit 28 for controlling the switching operation of the electromagnetic valves 20, 23, 24 and the electromagnetic switching valve 16d of the exhaust valve mechanism 16. The valve control unit 28 is connected to a melt limit sensor 15 and a vacuum limit switch 10 that can engage with a limit bar 9 attached to the plunger 8. When the vacuum limit switch 10 is engaged with the limit bar 9, the vacuum limit switch 10 sends a signal S1 to that effect to the valve control unit 28. Further, when the molten metal sensor 15 senses the molten metal, it sends a signal S2 to that effect to the valve controller 28.

Next, the casting method of the embodiment of the present invention performed by the casting apparatus 1 having the above-mentioned structure will be described.

In the initial state, the plunger tip 7
Is in the retracted position shown in FIG. The electromagnetic switching valve 16d is in the state shown in FIG. 2, and the exhaust valve 16 is in the open state.
The atmosphere / vacuum switching solenoid valve 20 is in the state shown in FIG. 1, and the air path 19 is connected to the atmosphere path 21.
The atmosphere opening solenoid valve 23 is in the open state shown in FIG. 1, and the air blowing solenoid valve 24 is in the closed state shown in FIG.

In this state, the electromagnetic pump 4 of the EMP device 2
Is operated to supply hot water into the injection cylinder 6. Here, since the injection cylinder 6 and the cavity 13 are open to the atmosphere, the atmosphere corresponding to the volume of the molten metal supplied into the injection cylinder 6 is discharged from the injection cylinder 6 through the cavity 13 and the degassing passage 14. To be done. Therefore, a stable molten metal amount can be supplied to the cylinder 6 by the original molten metal feeding output of the electromagnetic pump 4.

When the electromagnetic pump 4 is operated for a predetermined time to supply a desired amount of molten metal into the injection cylinder 6, the electromagnetic pump 4 is stopped. After this, the plunger tip 7 is advanced from the retracted position. When the plunger tip 7 reaches a predetermined set position, the limit bar 9 engages with the vacuum limit switch 10. Upon receiving the signal S1 from the vacuum limit switch 10, the valve control unit 28 switches the atmosphere / vacuum switching electromagnetic valve 20 to set the air path 19 to the vacuum path 22.
Connect to. As a result, the gas vent passage 14 of the cavity 13 communicates with the vacuum passage 22, and the air in the cavity 13 is forcibly sucked by the vacuum pump 27. At this stage, the electromagnetic valve 23 for opening to the atmosphere is maintained in the open state, and the electromagnetic valve 24 for blowing air is also maintained in the closed state. By continuously advancing the plunger tip 7, the molten metal is injected into the cavity 13 and vacuum casting is performed. Here, since the gas in the cavity 13 is sufficiently discharged by the vacuum pump 27, the gas is not compressed and remains inside the product.

When the molten metal enters the degassing passage 14 immediately before the completion of filling the molten metal in the cavity 13, the molten metal detection sensor 15 detects the molten metal. Upon receiving the signal S2 from the molten metal detection sensor 15, the valve control unit 28 changes the electromagnetic switching valve 1
6d is switched to send compressed air from the compressor 16e to the piston front chamber 16f of the cylinder 16a. The piston 16c retracts to the right in FIG.
6b is seated on the valve seat 14a and the valve mechanism 16 is closed. As a result, the connection between the gas vent passage 14 and the air passage 19 is cut off, and the molten metal is prevented from flowing into the air passage 19.

When the vacuum casting is completed after a predetermined time has passed since the signal S1 was received, the valve control unit 28 returns the atmosphere / vacuum switching solenoid valve 20 to the switching source position (the position shown in FIG. 1). Then, the air path 19 is connected to the atmosphere path 21. Then, the movable platen 17 is moved to open the cavity 13 and take out the casting.

Next, the valve controller 28 controls the electromagnetic switching valve 16
Switch d to return to the original position (position in FIG. 2). Compressed air from compressor 16e is cylinder 16a
Sent to the piston rear chamber 16g of the piston 16c
2 moves leftward in FIG. 2 to separate the valve member 16b from the valve seat 14a, open the valve mechanism 16 and connect the gas vent passage 14 to the air passage 19. At this point, the operation of the air blow device 25 starts. At the same time, the control unit 2
8 switches the atmosphere opening solenoid valve 23 to the closed state, switches the air blow solenoid valve 24 to the open state, and opens the atmosphere path 21.
Is connected to the air blow device 25. In this way, the air blow cleaning of the exhaust valve mechanism 16 is performed.

When a predetermined time has passed after the start of the air blow cleaning and the air blow cleaning is completed, the air blow device 25
To stop. At the same time, the valve control unit 28 switches the air blow solenoid valve 24 to the closed state (state of FIG. 1) and the atmosphere opening solenoid valve 23 to the open state (state of FIG. 1) to open the atmosphere path 21 to the atmosphere. Let The plunger tip 7 is returned to the retracted position shown in FIG. 1, is returned to the initial state, and enters the standby state for the next casting.

The present invention is not limited to the casting method of the above embodiment, and various modifications can be made without departing from the spirit of the present invention. Further, the casting apparatus for carrying out the casting method of the present invention is not limited to the above example.

[0024]

According to the casting method of the present invention described in detail above, hot water can be supplied to the injection cylinder by the EMP device, and the mold cavity can be used when the molten metal is injected into the mold cavity. Since the inside can be sufficiently exhausted, a stable hot water supply amount can be secured, and gas entrainment inside the product can be significantly reduced, and a high quality product can be cast.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a casting apparatus for carrying out a casting method according to an embodiment of the present invention.

FIG. 2 is an enlarged detailed view of a portion A of the casting apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casting apparatus 2 EMP apparatus 3 Holding furnace 4 Electromagnetic pump 5 Molten metal path 6 Injection cylinder 7 Plunger chip 13 Cavity 14 Gas vent passage 15 Molten metal detection sensor 16 Exhaust valve mechanism 19 Air path 20 Air / vacuum switching solenoid valve 21 Air path 22 Vacuum path 23 Solenoid valve for opening to the atmosphere 24 Solenoid valve for air blow 25 Air blow device 27 Vacuum pump 28 Valve control unit

Claims (1)

[Claims] 1. A casting method using an electromagnetic pump, wherein a molten metal supplied into the injection cylinder by an electromagnetic pump is injected into a mold cavity communicated with the injection cylinder by a plunger tip. When supplying the molten metal into the cylinder, the mold cavity is communicated with the atmosphere system, and when the molten metal is injected into the mold cavity by the plunger tip, the mold cavity is communicated with a vacuum exhaust system for vacuum casting. A casting method using an electromagnetic pump characterized by the above.