JP4139127B2 - Molten metal holding furnace for casting - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molten metal holding furnace for casting having a function of press-fitting molten metal such as aluminum or aluminum alloy into a mold cavity of a casting machine.
[0002]
[Prior art]
In a casting machine that casts aluminum such as automobile parts and aluminum alloy, the configuration in which the molten metal is filled in the mold by applying pressure to the molten metal surface in the molten metal holding furnace is actual 2-35399 etc. It is known as follows.
Furthermore, a hot water pipe is connected to the lower part of the molten metal holding furnace, an inlet end of the hot water pipe is opened in the furnace, and a sealed pot communicating with the molten metal holding furnace is immersed therein. The mold cavity arranged at a position separated from the inside is communicated with the inside of the sealed pot by the tapping pipe, and the inlet end of the hot water pipe in the molten metal holding furnace and the inlet end of the tapping pipe in the sealed pot, respectively. Japanese Patent Application Laid-Open No. 2001-276964 discloses a configuration in which a predetermined amount of molten metal is supplied into a closed pot by opening / closing control using an on / off valve, and the molten metal is supplied into a mold cavity. .
[0003]
[Problems to be solved by the invention]
By the way, all the above-mentioned configurations relate to a configuration in which the molten metal is supplied into the mold cavity at a pressure of O.5 to 1.Okg / cm <2>. That is, in such a configuration, only the pressure in the above range can be applied to the molten metal due to the strength and porosity of the refractory material used in the molten metal holding furnace. That is, when the pressure is increased, the molten metal penetrates into the pores of the furnace wall refractory material and cracks and cracks are generated in the refractory material. On the other hand, when the applied pressure is low, the hot water in the mold cavity is not sufficiently performed. In particular, the more complicated the shape of the mold, the more uneven the pressure in each part of the cavity, causing shrinkage cavities, and indentations and thinning of the casting.
[0004]
Furthermore, in the molten metal holding furnace, a hot water supply pipe is connected to the lower part, an inlet pot end of the hot water pipe is opened in the holding furnace, and a sealed pot is arranged to communicate with the molten metal holding furnace. The mold cavity arranged outside the molten metal holding furnace is communicated with the inside of the sealed pot by the tapping pipe, and the inlet end of the hot water pipe and the inlet end of the tapping pipe are controlled to be opened and closed by the opening / closing control valves, respectively. This configuration is disclosed in Japanese Patent Laid-Open No. 2001-276964. After opening the inlet end of the hot water supply pipe and supplying the molten metal to the same level as the molten metal holding furnace in the sealed pot, the inlet end of the hot water pipe is closed and the inlet of the hot water pipe is further closed. After opening the end, after applying pressure in the sealed pot and supplying the molten metal into the mold cavity outside the furnace until the molten metal level sensor falls to a predetermined molten metal surface level required for one tapping, The entrance end of the tapping pipe is closed. And the amount of hot water is adjusted by this.
[0005]
In such a configuration, since the inside of the sealed pot is pressurized, the influence of pressure on the strength and porosity of the refractory material used in the molten metal holding furnace can be avoided. By the way, this structure is a structure which supplies the molten metal in an airtight pot to the casting machine arrange | positioned out of the molten metal holding furnace. That is, in the tapping pipe, it is necessary to always keep the molten metal filled in order to prevent oxidation in the pipe. For this reason, the amount of tapping is controlled by the mold level by controlling the level of the tapping water in the sealed pot. When it matches the volume of the cavity and reaches the predetermined hot water level (predetermined amount of hot water), the inlet end of the hot water pipe is closed, and the hot water pipe is always filled with molten metal to prevent the molten metal from returning. I am doing so.
[0006]
For this reason, this configuration has the following problems.
1) This configuration is to supply the molten metal in the sealed pot to the casting machine placed outside the molten metal holding furnace, and the length of the hot water discharge pipe is 1.Okg due to the shield limit at the joint of the pipe. It cannot supply hot water at a pressure of more than / cm2. That is, it is based on the structure which presupposes supplying a molten metal in a mold cavity with the pressure of O.5-1.Okg / cm <2>.
2) The structure is complicated by requiring devices such as an open / close control valve and a hot water level sensor for controlling the opening and closing of the inlet end of the tapping pipe.
3) It is necessary to install a heater around the long tapping pipe that reaches the mold cavity so that the molten metal in the tapping pipe drawn out of the furnace is not cooled and solidified, and the equipment becomes large.
[0007]
That is, the above-described configuration in which the closed pot according to Japanese Patent Laid-Open No. 2001-276964 is disposed in the furnace is for controlling the amount of hot water discharged into the mold cavity disposed outside the furnace, and is suitable for high-pressure hot water supply. However, the configuration is complicated and large.
[0008]
An object of the present invention is to provide a molten metal holding furnace for casting which has a simple structure and can supply molten metal at a high pressure to perform high-precision casting.
[0009]
[Means for Solving the Problems]
The invention of the present application has a closed pot formed in the furnace so that a molten metal inlet is formed in the lower part and the molten metal inlet is located below the molten metal surface,
A casting machine disposed immediately above the sealed pot;
Stokes, which is held in a liquid-tight manner on the closed pot, communicates with the mold cavity at the upper end and communicates with the inside of the closed pot,
A gas supply path for controlling the supply of pressurized gas to the sealed pot;
A molten metal inlet comprising a valve for opening and closing the molten metal inlet, a driving device for converting the valve into an open position and a closed position, and a valve rotating mechanism for rotating the valve with the molten metal inlet closed. An opening and closing control device for opening and closing,
When hot water is discharged to the mold cavity, the open / close control device is driven to close the molten metal inlet, the gas supply path is opened, and pressurized gas is supplied into the sealed pot. This is a molten metal holding furnace for casting.
[0010]
In such a configuration, the molten metal inlet is opened, the molten metal in the hot water supply chamber is introduced into the sealed pot, the molten metal inlet is closed, and then it is difficult to react with molten metal such as nitrogen gas or dry air. By sending a pressurized gas into the sealed pot and applying a high pressure to the molten metal surface, the molten metal is injected into the mold cavity from the Stokes in the sealed pot. When the molten metal is solidified in the mold cavity, the pressure application by the pressurized gas is released and the molten metal inlet is opened. As a result, the molten metal remaining in the Stokes descends, and the molten metal flows into the sealed pot, increasing the level of the molten metal.
[0011]
Further, in such a configuration, pressure is applied only in the sealed pot, and the hot water discharge pipe is not drawn out of the closed pot, and there is no pipe joint, so that a high pressure of 1. Okg / cm2 or more is required. Can be applied. As a result, the molten metal can flow smoothly into the cavity of the casting machine, the adhesion between the molten metal and the casting machine is improved, the casting surface is improved, and the casting product is dense, high in strength and has no nest. Obtainable.
[0012]
Further, since it is only necessary to apply pressure to the sealed pot, management of the amount of hot water is not required, and the control mechanism is simplified.
[0013]
Here, the open / close control device that opens and closes the molten metal inlet includes a valve that opens and closes the molten metal inlet, a drive device that converts the valve into an open position and a closed position, and a valve that rotates with the molten metal inlet closed. It consists of a moving valve rotation mechanism . By the rotation of the valve by the valve rotation mechanism, the molten metal solidified at the molten metal inlet is removed. Thereby, the adhesiveness with the periphery of a valve molten metal inlet improves, and the shielding property in a sealing pot increases. For this reason, even if a high pressure is applied to the closed pot, the molten metal does not leak out from the closed pot, and an open / close mechanism optimal for high pressure casting is obtained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIGS. 1, 2, and 4, the molten metal holding furnace 1 for casting according to the present invention includes a holding chamber 2 and a hot water supply chamber 3 communicating with the holding chamber 2.
[0015]
A hot water lid 4 is provided at the upper end of the holding chamber 2 and is driven to open and close by a lid opening / closing device 5. Then, the hot water lid 4 is opened almost regularly, and molten metal is injected and added into the holding chamber 2 from a separate melting furnace (not shown). A necessary number of heaters 6 are attached near the bottom of the holding chamber 2 to keep the molten metal at a predetermined temperature. The holding chamber 2 may be divided into a hot water dust removing chamber and a holding temperature control chamber by the filter 10 or the like.
[0016]
The holding chamber 2 is provided with a molten metal shut-off valve 7, and an amount of molten metal necessary for casting is sent from the holding chamber 2 to the hot water supply chamber 3 by opening and closing the opening 8 with the hot water supply chamber 3. The molten metal shut-off valve 7 has a structure in which a die is attached to the lower part of the shaft, is connected to a cylinder 9 attached to the upper part, and is moved up and down by driving the cylinder 9 to open and close the opening 8.
[0017]
A heater 11 is provided near the bottom of the hot water supply chamber 3, and the molten metal is always maintained at a temperature suitable for casting. The main part of the present invention is that the sealed pot 12 that holds the straight tubular Stokes 19 at the center of the hot water supply chamber 3 is arranged so that the lower part is immersed under the hot water surface. The main part of the present invention will be described below.
[0018]
Here, the straight tubular Stokes 19 is held in a liquid-tight state directly above the sealed pot 12 , and the upper end communicates with the mold cavity 41 and the lower end communicates with the inside of the sealed pot 12. That is, the upper straight of the sealed pot 12, includes an upper mold S1 and the lower mold S2, casting machine 40 which form the mold cavity 41 is disposed therebetween. A connecting pipe 42 communicating with the mold cavity 41 is connected to the upper end of the Stokes 19.
[0019]
The sealed pot 12 is made of a ceramic material that does not break even when a pressure of about 10 kg / cm 2 is applied to the inside thereof, and that the molten metal does not enter the material of the sealed pot 12 . A molten metal inlet 13 communicating with the opening 12 a is formed in the lower portion of the sealed pot 12, and only a quantity of molten metal necessary for one casting is supplied from the hot water supply chamber 3 through the molten metal inlet 13. Introduced in.
[0020]
The molten metal inlet 13 is controlled to be opened and closed by an opening and closing control device shown in an enlarged manner in FIG. Here, the molten metal inlet 13 is opened and closed by a bowl-shaped valve 14 that is advanced and retracted by driving the cylinder 15. More specifically, the rod 16 of the cylinder 15 is pivotally supported at one end of the arm 16 supported at the center by the bearing 16 a so as to be tiltable, and the rotation holding portion 16 b provided at the other end of the arm 16. The upper end of the bowl-shaped valve 14 is rotatably held. This bowl-shaped valve 14 is formed in a lid body 20 that shields the hot water supply chamber 3, and is inserted into a guide 22 that produces an upward and downward guiding action. A spherical end surface 14a is formed at the lower end. When the rod 15a of the cylinder 15 is driven to advance, the arm 16 tilts clockwise around the bearing 16a, and along with this, the hook-like valve 14 moves downward along the guide 22, and the hook-like valve The spherical end surface 14 a of 14 is in pressure contact with the mouth portion 27 to shield the molten metal inlet 13. The mouth portion 27 of the molten metal inlet 13 is also subjected to spherical processing, so that the spherical end surface 14a is in surface contact with the molten metal inlet 13 in a uniform manner. Similarly, when the rod 15a of the cylinder 15 is retracted, the arm 16 tilts counterclockwise, the bowl-shaped valve 14 moves upward, and the molten metal inlet 13 is opened. Thus, the opening and closing of the molten metal inlet 13 is controlled by the control of the cylinder 15, and thereby the opening and closing control device 25 is configured. In such a configuration, the sealed pot 12 does not have a low pressure of 0.5 to 1.0 kg / cm 2 as in the prior art, but the above-mentioned 10 kg / cm 2 (the applicable range is 1.0 kg / cm 2 to A high pressure of about 11 kg / cm2) is applied. For this reason, a pressure contact force that can block the molten metal inlet 13 against such pressure is required.
[0021]
Here, in order to completely seal the molten metal inlet 13 with the valve 14, the spherical end surface 14 a of the bowl-shaped valve 14 is pressed against the molten metal inlet 13, and then the valve 14 is rotated and tightened by the valve rotating mechanism 17. ing. As shown in an enlarged view in FIG. 3, the rotation mechanism 17 rotatably supports the upper end of the bowl-shaped valve 14 in a concave groove of a rotation holding portion 16 b provided at the other end of the arm 16. The rod 24a of the cylinder 24 is linked to the rod-shaped valve 14 via the link 26 in the tangential direction, and the rod-shaped valve 14 is reciprocally rotated by the forward / backward drive of the rotating cylinder 24. It is. In order to make the operation of the mechanism smooth, play is provided in each of the connecting portions. Thus, when the spherical end surface 14 a of the bowl-shaped valve 14 is in close contact with the inner peripheral edge of the molten metal inlet 13, the bowl-shaped valve 14 is rotated by the drive of the rotating cylinder 24, and the molten metal inlet 13 is connected. The closeness is ensured, the molten metal inlet 13 is sealed, and the blocking property in the sealed pot 12 is improved. Therefore, as described above, even if a high pressure is applied to the sealed pot 12, molten metal from a sealed pot 12 within, it does not leak.
[0022]
The opening of the sealed pot 12 is shielded by the housing 30, and the upper end of the straight tube-shaped Stokes 19 is held in a liquid-tight state by the housing 30, and the lower end of the Stokes 19 is opened downward inside the sealed pot 12. ing. A heater 31 for heating the Stokes 19 is held by the housing 30. The heater 31 has a short heat insulation length and a high ambient atmosphere as compared with the structure in which the molten metal from the sealed pot is supplied to the mold cavity of the casting machine outside the molten metal holding furnace by the discharge pipe. Therefore, there is an excellent advantage that a simple structure can be obtained and temperature control is simple. In some cases, the heater may be omitted.
[0023]
In addition, a gas supply path 18 is connected above the sealed pot 12, and when casting, the molten metal inlet 13 is sealed by the bowl-shaped valve 14, and nitrogen, dry air, etc. of about 10 kg / cm 2 are not used. A pressurized gas composed of an active gas is sent to pressurize the molten metal surface. When the molten metal is pressurized, the lower end opening of the Stokes 19, the molten metal is injected into the formed mold cavity 41 between the upper mold S 1 and the lower mold S2, which is placed in a closed pot 12 upward.
[0024]
Next, an operation example of the molten metal holding furnace 1 for casting according to the present invention will be described with reference to the drawings. When the molten metal is transported to the holding furnace 1 by a ladle or the like, the lid opening / closing device 5 is operated to open the hot water lid 4, and after the molten metal is injected into the holding chamber 2, the hot water lid 4 is closed again. And the molten metal is uniformly heated by the heater 6, and temperature unevenness is eliminated. Although the molten metal shut-off valve 7 normally closes the opening 8, when the ongoing casting operation is completed, the cylinder 9 is operated to raise the molten metal shut-off valve 7, and the opening 8 is opened so that only the amount necessary for the next casting is obtained. The molten metal is moved to the hot water supply chamber 3. When a level sensor (not shown) or the like detects that a certain amount of molten metal has moved to the hot water supply chamber 3, the molten metal cutoff valve 7 is lowered and the opening 8 is closed.
[0025]
With the configuration described above, a certain level of molten metal is always stored in the hot water supply chamber 3. When casting into the mold cavity 41 of the molds S1 and S2 is started, the cylinder 15 is first operated to raise the valve 14 and open the molten metal inlet 13. Thereby, the molten metal enters the sealed pot 12 from the hot water supply chamber 3 until it becomes equal to the level of the hot water in the hot water chamber 3, and the molten pot necessary for at least one casting is supplied into the sealed pot 12. In this case, the molten metal may be forcibly sucked into the sealed pot 12 using a suction pump (not shown) or the like. When the amount of molten metal necessary for the hot water enters the sealed pot 12, the cylinder 15 is operated, the bowl- shaped valve 14 is lowered via the arm 16, and the spherical end face 14a is pressed against the molten metal inlet 13 to be in a closed state. . In order to make the sealed state of the molten metal inlet 13 complete, thereafter, the bowl-shaped valve 14 is rotated by the rotating mechanism 17 to enhance the adhesion.
[0026]
Next, an inert gas is fed into the sealed pot 12 through the gas supply path 18 by a pressure pump, and a pressure of about 10 kg / cm 2 is applied to the molten metal surface. Nitrogen or dry air is used as the inert gas. By this pressurization, the molten metal flows through the Stokes 19 into the mold cavity 41 constituted by the upper mold S1 and the lower mold S2, and casting is performed. During casting , a constant pressure is continuously applied to the sealed pot 12. At this time Stokes 19 is heated by the heaters 31, solidification of the molten metal is prevented. When the casting operation is completed, the inert gas is discharged from the gas supply path 18 to release the pressure in the sealed pot 12. Thereby, the molten metal remaining in the Stokes 19 flows down. Then, the valve 14 is separated from the molten metal inlet 13 again, and the molten metal necessary for the next time is introduced into the sealed pot 12. The casting operation is continued while repeating the above operation.
[0027]
In such a casting operation, the ceramic pot 12 is provided and pressure is applied to the pot 12 so that the molten metal does not enter the pores of the furnace wall refractory material due to the pressure. In addition, since the hot water discharge pipe is not drawn out of the sealed pot and there is no connecting portion of the pipe, a high pressure of 1.Okg / cm 2 to 11 kg / cm 2 or more can be applied. For this reason, while applying a high pressure to the molten metal, it can flow from the Stokes 19 into the mold cavity 41 and can be maintained in a pressing state at a high pressure. As a result, the adhesion between the molten metal and the inner surface of the mold cavity 41 is improved. Therefore, the solidification control of the molten metal in the mold cavity 41 can be appropriately performed. And the fine shrinkage nest | generation which generate | occur | produces in a casting skin surface layer will be improved. In addition, since the hot metal power is increased, the shrinkage nest caused by insufficient supply of molten metal can be eliminated and the strength is improved.
[0028]
【The invention's effect】
As described above, according to the present invention, a closed pot in which Stokes is disposed in the center is provided in the furnace, a casting machine is disposed immediately above the closed pot, and the mold cavity and Stokes are connected. Thus, pressure is applied to the inside of the sealed pot, and there is a hot water outlet pipe that is drawn out to the outside without fear that the molten metal will enter the pores of the furnace wall refractory material and damage the furnace wall. Since it is not a thing, it becomes possible to apply a high pressure of 1.Okg / cm2 or more in the sealed pot. For this reason, by flowing the metal from the Stokes into the mold cavity while applying a high pressure to the molten metal , the adhesion between the molten metal and the mold surface is improved and the thermal conductivity is improved. In addition, high-precision casting can be performed at low cost without changing or complicating the furnace wall structure of the molten metal holding furnace for casting.
Furthermore, a device such as an open / close control valve for controlling opening / closing of the inlet end of the hot water pipe is not required, and temperature management in the hot water pipe drawn out of the furnace is not required, so that the equipment is simple and inexpensive.
[0029]
Here, since the opening / closing control device for opening and closing the molten metal inlet is provided with a valve rotating mechanism for rotating the valve for opening and closing the molten metal inlet while the molten metal inlet is closed , the valve and the molten metal inlet The sealing edge in the closed pot is improved, and even when a high pressure is applied to the closed pot, the molten metal does not leak from the closed pot, providing an optimal opening / closing mechanism for high pressure casting. .
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a molten metal holding furnace 1 for casting according to an embodiment of the present invention.
FIG. 2 is a vertical side view of a hot water supply chamber 3;
FIG. 3 is an enlarged vertical side view of a main part.
FIG. 4 is a plan view of a molten metal holding furnace 1 for casting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Molten metal holding furnace for casting 2 Holding chamber 3 Hot water supply chamber 12 Sealed pot 13 Intake 14 Valve 15 Cylinder 18 Gas supply path 19 Stokes 40 Casting machine 41 Mold cavity

Claims (1)

A sealed pot is formed in the furnace such that a molten metal inlet is formed in the lower part and the molten metal inlet is located below the molten metal surface,
A casting machine disposed immediately above the sealed pot;
Stokes, which is held in a liquid-tight manner on the closed pot, communicates with the mold cavity at the upper end and communicates with the inside of the closed pot,
A gas supply path for controlling the supply of pressurized gas to the sealed pot;
A molten metal inlet comprising a valve for opening and closing the molten metal inlet, a driving device for converting the valve into an open position and a closed position, and a valve rotating mechanism for rotating the valve with the molten metal inlet closed. An opening and closing control device for opening and closing,
When the hot water is discharged into the mold cavity, the open / close control device is driven to close the molten metal inlet, the gas supply path is opened, and the pressurized gas is supplied into the sealed pot. A molten metal holding furnace for casting.

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