Patent Application
20070017320
1. Field of the Invention
The present invention relates to a method and a device for removing slag, which is generated on a surface of molten metal in a metal furnace.
2. Description of the Related Art
When a metal material is liquidized in a liquidizing furnace by heating in a vacuum atmosphere so as to form a molten metal and cast into a mold for precise casing, slag is generated on a surface of the molten metal. Since it is difficult to remove the slag, the molten metal is cast in the mold with the slag, the slag affects the quality of the produced cast products. Particularly in producing precise cast products (for example, parts for air and space industry), any slag is not allowed to be contained. Thus, any contaminant of the slag significantly affects the yield of the cast products particularly in the precise cast products field.
Heretofore, when the molten metal is cast into the mold, slag is conventionally prevented from entering into the mold by the following methods: One method is to remove the slag by tilting the furnace to the other side of the mold for removing the slag before pouring the molten metal into the mold. Another method is to remove the slag by installing a filter at an entrance of the mold for filtering the slag.
However, even though the slag can be removed by tilting the furnace to the other side of the mold before pouring the hot melt into the mold, it is difficult to remove the slag perfectly. By installing a filter at entrance of the mold for filtering the slag, it is easy to remove a larger size of the slag, but it is difficult to remove a smaller size of the slag. If trying to remove the smaller size of the slag by the filter, it is required to make the filter finer, however when making the filter finer, it causes slower of flowing speed of the molten metal into the mold and generates bad products because of lack of the molten metal flowing into the mold. Further, the filter chips easily, and when chip of the filter is entered into the mold with hot melt, it generates bad products because of contaminants of filter chip.
Further, a method of removing slag, which is floating on a surface of the molten metal, in air atmosphere is known as Japanese laid-open patent publication No. H5-240588.
It is therefore an object of the present invention to provide a method and a device for removing slag, which is capable of removing slag efficiently in a liquidizing furnace for precise-casting, in which any contaminant of slag is not allowed.
To achieve the above object, there is provided in accordance with the present invention, a method and a device for removing slag comprises traveling a filter of heat-resistant porous ceramics along a surface of the molten metal and removing the slag, which is generated by liquidizing metal material by heating and floating on the surface of the molten metal in the furnace.
According to the present invention, since the filter passes the molten metal and catches slag only, therefore, by traveling the filter along a surface of the molten metal, on which slag is floating, the filter can catch slag and remove slag from the molten metal effectively. Thus, by pouring the molten metal without any contaminants of slag into a mold directly, precise cast products can be produced with high yield.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, which illustrate a preferred embodiment of the present invention by way of example.
Preferred embodiments will be described with referring to the attached drawings. Like or corresponding parts are denoted by the same reference characters throughout views, and will not repetitively be described.
When temperature of the molten metal A reaches to a predetermined temperature, induction heating is stopped and molten metal A becomes settled down to be a quiet state. Then, since the specific gravity of the slag is lower, the slag becomes floating on the surface of the molten metal A. As shown in
Molten metal A, from which slag has been removed, is poured directly (without passing through filter) to mold 15 as shown in
One end of arm 22 is rotatably fixed to the lower end of cylinder 32. Arm 22 is provided with a long-width hole 26, and a pin 24 disposed at the lower end of rod 31 is engaged to long-width hole 26 and then arm 22 is slidably fixed to rod 31. Another end of arm 22 is fixed to filter 21 by fixing element 23. Therefore, by moving rod 31 vertically relatively against cylinder 32, arm 22 can be rotated around pin 26 and radial position of filter 21 in crucible 12 is determined. Moving rod 31 and cylinder 32 vertically as one unit, vertical position of filter 21 in crucible 12 is determined. Rotating rod 31 and cylinder 32 around rod 31 as one unit, filter 21 travels rotating (in circumference direction) around rod 31 on the surface of hot melt A in crucible 12.
The device for traveling filter and removing slag can be operated at air atmosphere or at vacuum atmosphere. Also, the device can be operated manually or automatically by pre-inputting total quantity of metal to be liquidized and size of crucible, for example. In vacuum liquidizing and casting process, the process roughly comprises liquidizing metal, measuring temperature of the molten metal, settling down of the molten metal, removal of slag, measuring temperature of the molten metal, and casting the molten metal into a mold to produce cast products. The device can be operated alone or in combination with a temperature measuring equipment (thermo-couple thermometer, radiation thermometer) and switching each process in several seconds while keeping vacuum atmosphere.
Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-212916 | Jul 2005 | JP | national |
