JPH09239510A - Apparatus for supplying molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oxidation of molten metal and to attain a continuous stable production of a formed product by bypassing the molten metal from a supplying pipe line to a holding furnace during time when the supplement of the molten metal into a cavity is not needed, in forming of the low m.p. molten metal. SOLUTION: A molten metal supplying apparatus 100 is provided with the holding furnace 10 for the molten metal M, a molten metal pump 20 for discharging the molten metal M from the holding furnace 10, a gate valve 50 for controlling communication and shut-off of the discharged molten metal M into a die cavity 2 and a pipe line 40 for connecting the molten metal supplying pump 20 and the gate valve 50. This apparatus is constituted to be provided also with a returning pipe line 60 for returning back the molten metal M flowing into the gate valve 50 to the holding furnace 10. When the molten metal M is not supplied and filled into the die cavity 2. In this case, the supplying pipe line 40 connecting the holding furnace 10 with the gate valve 50 and the returning pipe line 60 are made flexible only at near the gate valve 50 and the outsides are heat insulated with heaters 80b and the remaining parts are made to fixed type double pipe lines for passing the molten metal M in the inside and a heating medium on the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies molten metal of a low melting point alloy such as Sn-Bi alloy for molding a core used for resin injection molding to a mold cavity of a molding apparatus such as a die casting machine. The present invention relates to a hot water supply device, and particularly to a hot water supply device in which molten metal is prevented from being oxidized.

[0002]

2. Description of the Related Art Conventionally, low-melting-point metals such as Sn-Bi alloys, which are generally used for low-melting-point cores, are easily oxidized.
In a closed system, molten metal is supplied from a holding furnace into a mold cavity of a molding machine. At this time, the molten metal pipe from the holding chamber to the mold cavity is one system, and a device called a nozzle is provided at the connection part to the mold cavity, and the molten metal flows through the nozzle into the mold cavity. To be filled. This conventionally used nozzle is open to the atmosphere when the mold cavity is not filled with the molten metal.

[0003]

However, the above-mentioned nozzle system has the following problems. Oxidation of the molten metal is inevitable because the nozzle is open to the atmosphere. Therefore, there is much wear associated with the oxidation of metal, which greatly increases the cost of molded products and
Oxide causes damage to sliding parts and deterioration of core quality. Since the conduit from the molten metal holding chamber to the mold cavity has one system, if the molten metal is not filled in the mold cavity for a long time, the molten metal stays in the conduit. Therefore, it is necessary to keep the temperature of the pipe sufficiently warm so that the molten metal in the pipe does not solidify. Therefore, the pipeline including the heat insulating layer becomes very large, which causes a very large restriction on the attachment to the mold. When the mold cavity is not filled with molten metal, the nozzle is open to the atmosphere.To prevent overflow from the nozzle and to prevent metal oxidation due to lowering of the molten metal level, the nozzle mounting position should be the molten metal melt. It is limited to a position slightly higher than the surface, and it is necessary to minimize fluctuations in the molten metal surface. Since the nozzle is movable, the molten metal is supplied by double flexible hoses. The hose keeps the molten metal warm by passing the molten metal inside and the heat medium outside.
Since it is a double hose, the outer circumference of the inner hose and the inner circumference of the outer hose are rubbed and damaged by the lifting and lowering operation of the nozzle, and the molten metal or the heat medium may leak and be mixed with each other.

[0004]

In order to solve the above problems, in the present invention, in the first invention, hot water is supplied to a mold cavity of a molding apparatus such as a die casting machine by supplying molten metal of a low melting point alloy. An apparatus comprising a molten metal holding furnace, a hot water pump for discharging the molten metal from the holding furnace,
It is equipped with a gate valve for controlling communication / cutoff of molten metal discharged from the hot water supply pump into the mold cavity, and a pipe line connecting the hot water supply pump and the gate valve, and melted in the mold cavity. The structure was provided with a return pipe for returning the molten metal flowing into the gate valve from the gate valve to the holding furnace when the metal was not filled. Further, in the second invention, the pipe connecting the holding furnace and the gate valve and the return pipe are formed of a flexible pipe only in the pipe in the vicinity of the gate valve, and the outside is kept warm by the heater, and the remaining pipe is placed inside. It was a fixed type double pipe through which the molten metal was passed and the heat medium was passed to the outside.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A hot water supply apparatus of the present invention is a hot water supply apparatus for supplying molten metal of a low melting point alloy to a mold cavity of a molding apparatus such as a die casting machine, which comprises a molten metal holding furnace and a molten metal. A hot water supply pump for discharging the molten metal from the holding furnace, and a gate valve for controlling connection / disconnection of the molten metal discharged from the hot water supply pump into the mold cavity,
A return line for returning the molten metal flowing to the gate valve to the holding furnace from the gate valve when the mold cavity is not filled with the molten metal. When the molten metal is not supplied into the mold cavity, the molten metal is always made to flow in the pipeline from the holding furnace to the gate valve and the return pipeline from the gate valve to the holding furnace. By circulating the molten metal in the route of holding furnace → gate valve → holding furnace, the molten metal is prevented from being exposed to the outside atmosphere and solidification of the molten metal in the pipeline is prevented. Therefore, in the second invention, the pipe connecting the holding furnace and the gate valve and the return pipe are formed of a flexible pipe only in the pipe in the vicinity of the gate valve, and the outside is kept warm by the heater, and the remaining pipe is placed inside. As a fixed double pipe through which molten metal is passed and a heat medium is passed to the outside, the molten metal was kept warm.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 are all related to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of a water heater, FIG. 2 is a structural diagram of a gate valve (when moving forward), and FIG. 3 is a structure of a gate valve (when moving backward). 4 and 5 are hydraulic circuit diagrams of the gate valve.

As shown in FIG. 1, a hot water supply apparatus 100 includes a holding furnace 10 for storing and holding molten metal M, a hot water supply pump 20 immersed in the holding furnace 10, a pump switching valve 30, and a molten metal M supply line. Supply pipe 40 and molten metal M
Gate valve 50 for controlling the communication and shutoff of the molten metal M and the return pipe 60 for returning the molten metal M from the gate valve 50 to the holding furnace 10.
And a communication cutoff valve 7 for the return pipe immersed in the holding furnace 10.
0 and a heat insulating device 80 for a pipeline.

The holding furnace 10 stores molten metal in a metal container, covers the upper opening, and heats and keeps the surroundings with a heating medium. A piston 20b is disposed so as to be slidable in the vertical direction via a servo motor 21 and a ball screw mechanism 22 in a cylindrical cylinder 20a which is disposed so as to be immersed in the molten metal and whose upper end is opened and whose lower end surface is sealed. The through hole 20c formed in the lower end surface of 20a is connected to the pump switching valve 30. The pump switching valve 30 includes a port that communicates with the holding furnace 10, a port that connects to the through hole 20c, and the supply conduit 4.
The valve body 36 at the lower end of the valve rod 34 which rises and falls in the vertical direction by the operation of the fluid pressure cylinder 32 is moved up and down inside the body 30a having a port communicating with the port 0 to communicate with each of these ports. Things.

The supply line 40 connected to one of the ports of the body 30a of the pump switching valve 30 is connected to the gate valve 5 via a fixed pipe and a flexible pipe connected to the fixed pipe.
Contact 0. As shown in FIG. 2, in the gate valve 50, a pressurizing plunger 50a, to which a piston rod of a pressurizing cylinder 50b is connected, is fitted in a through hole inside a cylindrical valve body 51, and is slidable in the axial direction. On the other hand, the entire gate valve 50 can be moved forward (upward) or backward (downward) by the operation of the hydraulic cylinder 52 connected to the valve body 51.
A pair of left and right openings are provided on the upper side surface of the valve body 51, and are connected to the supply conduit 40 and the return conduit 60, respectively.

On the other hand, in the other opening of the gate valve 50, a return pipe 60 is connected to the molten metal consisting of a flexible pipe and a fixed pipe connected to the flexible pipe, and the holding furnace 1
Through the communication shut-off valve 70 immersed in the holding furnace 10
Communicates with the molten metal inside. The gate valve 50 is provided with a temperature control pipe 80a through which the heat medium supplied by the temperature control device 80 passes. The gate valve 50 is
It is controlled by the hydraulic circuit shown in FIG. Communication shutoff valve 7
0 is the same as that of the pump switching valve 30 described above.
A port connected to the return pipe 60 and a port communicating with the molten metal in the holding furnace are bored in the body 70a fixed to a, and the fluid pressure cylinder 72 is operated to move up and down in the middle thereof. The valve body 76 at the lower end of the valve rod 74 is moved up and down so as to disconnect this port. Further, in the supply pipeline 40 and the return pipeline 60, the fixed pipe is a double pipe through which the molten metal is passed inside and the heat medium is passed outside, and the flexible pipe which is difficult to be a double pipe is a single pipe. The outside thereof is heated and kept warm by the flexible heater 80b. The hydraulic cylinder 32 and the hydraulic cylinder 72 usually use pneumatic cylinders rather than hydraulic cylinders.

The hot water supply apparatus 1 of the present invention thus configured
The operation of 00 will be described step by step below. (1) First, the valve body 36 in the pump switching valve 30 is lowered to the lower limit, the port of the supply pipe 40 is closed, and the inside of the holding furnace and the through hole 2 are closed.
After opening the port connecting 0c, the servo motor 21 is driven to raise the piston 20b of the hot water supply pump 20 via the ball screw mechanism 22 to take in a prescribed amount of molten metal M into the cylinder 20a. The communication cutoff valve 70 also lowers the valve body 76 to the lower limit, and cuts off the communication between the return line 60 and the holding furnace 10. (2) Next, the gate valve 50 is advanced in the mold cavity direction, the tip (upper end) of the gate valve 50 is pressed against the runner portion of the mold cavity, and the gate valve 50 is brought into close contact with the mold. (3) The pressurizing plunger 50a of the gate valve is retracted. (4) Raise the valve body 36 of the pump switching valve 30 to the upper limit,
The piston 20b of the hot water supply pump 20 is lowered to lower the cylinder 20.
The molten metal M in a is filled into the mold cavity via the supply pipe 40 and the gate valve 50. After the completion of filling, the state is maintained for a fixed time of about several seconds. (5) The pressurizing plunger 50a is pressurized in the forward direction (upward) by a force equivalent to the holding pressure to perform curing, and the valve body 76 of the communication cutoff valve 70 is raised to connect the return pipe 60 to the holding furnace 10. The molten metal is circulated in communication. (6) When the gate valve 50 is higher than the level of the holding furnace (in the case of FIG. 1), the pump switching valve 30 is closed (the valve body 36). (Downward) while keeping the communication cutoff valve 70 in the connected state (the valve body 76 is raised), the pressurizing plunger 50a is lowered, and the unsolidified metal in the runner portion is naturally dropped in the return pipe line 60 by its own weight into the holding furnace 10. return. (7) When the gate valve 50 is lower than the level of the holding furnace, the method of recovering the unsolidified metal in the runner portion of the mold cavity is to close the communication cutoff valve 70 and raise the valve body 36 of the pump switching valve 30. The supply pipe 40 and the hot water supply pump 20 are communicated with each other, the pressurizing plunger 50a is lowered, the piston 20b is raised, and a suction force is exerted on the supply pipe 40 to supply the supply pipe 40.
Through the holding furnace 10. (8) When the molten metal M is not supplied to the mold cavity, the supply pipe 40 and the return pipe 60 are used to forcibly circulate the molten metal. In that case, the pump switching valve 30
The valve body 36 of the cylinder 20 is raised to bring the communication cutoff valve 70 into the communication state, and the pressure plunger 50a is kept in the forward movement state.
The molten metal M taken in a is made to flow into the holding furnace 10 in the order of the supply pipe 40 → gate valve 50 → return pipe 60 by lowering the piston 20b. (9) When one shot is completed and the molten metal M is to be circulated during the waiting time such as opening the mold to take out the product or applying the release agent for the next shot, the gate valve 50 After retracting the mold from the mold, the pressure plunger 50a is held at the forward position, and the molten metal M is held in the order of the supply pipe 40 → gate valve 50 → return pipe 60 in the same manner as (8). Pour into 10. (10) In addition, in (8) and (9), the piston 20
When b reaches the lower limit and the transportation capacity is lost, the circulation of the molten metal M is temporarily stopped and the piston 20b is raised to take the molten metal into the cylinder 20a by the same procedure as in (1). In this case, when the molten metal in the cylinder is taken in, the molten metal in the holding furnace may be taken in through the route of the return pipe 60 → gate valve 50 → supply pipe 40. However, there is a risk that the air will be sucked from the seal portion by the suction in the opposite direction, and the molten metal may be oxidized by the contact with the air. Therefore, the circulation by the reverse flow is not performed. However, if there is no such concern due to the structure of the gate valve 50, it is also possible to perform reverse flow circulation during suction of the molten metal in the cylinder.

As described above, in the present invention, in order to control the passage and interruption of the molten metal M supplied from the hot water supply pump 20 by the gate valve 50 into the mold cavity, the molten metal M is introduced into the mold cavity. Since the gate valve 50 can be closed in the case where the molten metal M is not filled, the molten metal M is not exposed to the atmosphere. Further, since the molten metal M is circulated in the order of the holding furnace 10 → the gate valve 50 → the holding furnace 10, the internal pressure of the pipeline can be generally maintained higher than the atmospheric pressure, and air flows in from the sealing portion of the gate valve. Nothing. Therefore, the molten metal M is not oxidized, and wear due to oxidation of the metal, damage to the sliding portion due to the oxide, deterioration of the quality of the core, and the like can be minimized. Further, when the molten metal M is not filled in the mold, the molten metal M is circulated in the route of the holding furnace 10 → the gate valve 50 → the holding furnace 10. Therefore, the heat insulation equipment for the pipe lines 40 and 60 to the gate valve 50 is provided. Is greatly simplified compared to the conventional one. Therefore, restrictions such as the mounting position of the gate valve 50 on the mold are greatly eased. By circulating the molten metal M, it is possible to prevent the metal from being overheated and deteriorated by the heater. Furthermore, when the molten metal M is not filled in the mold cavity, the gate valve 50 can be closed and the molten metal M is not exposed to the atmosphere. Therefore, the position of the gate valve 50 and the holding furnace level There is no relational restriction, and there is no need to control the fluctuation of the molten metal level, which has been performed conventionally.

[0013]

As described above, in the hot water supply apparatus of the present invention, it is possible to inexpensively obtain a high-quality molded product of a low-melting point alloy in a wide range of molds without complicated control.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a hot water supply device according to an embodiment of the present invention.

FIG. 2 is a structural diagram of a gate valve (during forward movement) of the hot water supply device according to the embodiment of the present invention.

FIG. 3 is a structural diagram of a gate valve (when retracted) of the hot water supply device according to the embodiment of the present invention.

FIG. 4 is a hydraulic circuit of a gate valve of the hot water supply device according to the embodiment of the present invention.

[Explanation of symbols]

 1 mold 2 mold cavity 10 holding furnace 10a crucible 20 hot water supply pump 20a cylinder 20b piston 20c through hole 21 servo motor 22 ball screw mechanism 22a ball screw 22b ball nut 30 pump switching valve 30a body 32 fluid pressure cylinder 34 valve rod 36 valve body 40 Supply pipe 50 Gate valve 50a Pressurizing plunger 50b Pressurizing cylinder 51 Valve body 52 Hydraulic cylinder 60 Return pipe 70 Communication cutoff valve 72 Fluid pressure cylinder 74 Valve rod 76 Valve body 80 Temperature control device 80a Temperature control pipe 80b Flexible heater 100 Water heater M Molten metal

Claims (2)

[Claims] 1. A hot water supply apparatus for supplying molten metal of a low melting point alloy to a mold cavity of a molding apparatus such as a die casting machine, the holding furnace for the molten metal, and a hot water supply pump for discharging the molten metal from the holding furnace. , A gate valve for controlling communication / interruption of molten metal discharged from the hot water supply pump into the mold cavity, and a pipe line connecting the hot water supply pump and the gate valve are provided. A water heater comprising a return pipe for returning the molten metal flowing into the gate valve from the gate valve to the holding furnace when the molten metal is not filled. 2. The pipe connecting the holding furnace and the gate valve and the return pipe are formed of a flexible pipe only in the pipe in the vicinity of the gate valve, and the outside is kept warm by a heater, while the remaining pipe is filled with molten metal inside. The hot water supply apparatus according to claim 1, wherein the hot water supply device is a fixed double pipe through which a heat medium is passed to the outside.