JPH0726695U - Vacuum induction melting furnace - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a melting furnace capable of evenly dispensing the molten metal into each mold when the molten metal is dispensed into a plurality of small-volume molds in a vacuum induction melting furnace. To aim. [Structure] A small dispensing crucible 15 is provided between the induction melting furnace 14 and the mold 12, and a heater 16 is provided on the outer periphery of the small melting crucible 15, and the amount of molten metal is less than the amount of molten metal for one mold on the inner wall 18 of the small melting crucible 15. The level is provided with a step portion 18a, and the bottom portion 19 of the dispensing crucible 15 is provided with a small hole 19a.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention uses induction heating in vacuum or in an inert gas atmosphere, and all of them are high purity metals for semiconductors, metals easily reacting with oxygen, nitrogen or carbon such as Ti and Zr, and W, Mo and Ta. Vacuum induction melting furnace suitable for melting high melting point metals such as Nb, Nb and their alloys, especially when casting molten metal into a plurality of small molds The present invention relates to an improvement of a split-mold vacuum induction melting furnace for preventing a decrease in yield due to, for example, supplying molten metal and sticking the molten metal to an unrecoverable part due to a decrease in temperature.

[0002]

[Prior art]

 Conventionally, the following two types of vacuum induction melting furnaces have been used to melt the above-mentioned various metals to be melted in a vacuum or in an inert gas atmosphere and perform casting into several small molds. Was there. The first device tilts the induction melting furnace and directly casts it into individual molds. The second device was to install a small dispensing crucible with a hot water storage unit equipped with a heating device with a capacity larger than the capacity of one mold between the induction melting furnace and the mold. It is the one that comes out of the bath. In either case, a turntable carrying a plurality of molds is arranged in front of the tap hole of the induction melting furnace and operated by operating these from outside the vacuum vessel. In the first apparatus, the worker tilts the induction melting furnace to supply the molten metal to each mold while observing the situation where the worker is cast into the mold through the viewing window attached to the vacuum container. In the second device, the amount of molten metal that is larger than the capacity of one mold is first supplied to the dispensing crucible from the induction melting furnace, and then the dispensing crucible is tilted to supply the molten metal to the individual molds. As in the case of the first device, the worker also conducts monitoring from outside the vacuum container.

[0003]

[Problems to be Solved by the Invention] In the first device, the molten metal is melted in the induction melting furnace in an amount corresponding to the number of prepared molds. It is difficult to tilt the induction melting furnace without making it insufficient, and variations in the casting amount are likely to occur. In the second apparatus, as shown in the sectional elevation view of FIG. 3, by providing the dispensing crucible 1 provided with the heating apparatus 2, the above-mentioned drawbacks caused in the first apparatus are greatly improved, but The receiving part 3 for receiving the molten metal and the tapping part 5 for inclining by the tilting shaft 4 to inject the molten metal into the mold have a low temperature because they are far from the heating device, and are easily cooled, so that the molten metal solidifies. As a result, the supply amount may be insufficient, or the molten metal may be spilled due to the change in the shape of the receiving portion and the outlet portion due to solidification and adhesion. The present invention reduces the variation in the molten metal supply amount that occurs in a vacuum induction melting apparatus provided with such multiple molds, improves the yield, and supplies a fixed amount of molten metal to multiple molds easily and reliably. In addition, it is an object of the present invention to provide a vacuum induction melting apparatus for reducing the loss of molten metal.

[0004]

[Means for Solving the Problems]

 In the present invention, a heat insulating heat insulator is provided on the outer circumference between the induction furnace and the mold, a step portion is provided at a predetermined position on the inner wall, and a dispensing crucible having a tap hole on the bottom of the crucible is fixed. The above problems have been solved by.

[0005]

[Action]

 When the induction melting furnace is tilted and the molten metal is poured into the small crucible, the molten metal flows from the small hole at the bottom of the small melting crucible at a constant rate to the lower mold, and the molten metal level in the crucible rises and accumulates to the inner wall. Reach the step. If the tilting speed of the induction melting furnace is kept constant, the time it takes for the molten metal to reach the step of the dispensing crucible is constant, and therefore the amount of molten metal flowing down from the small hole at the bottom to the mold below is also constant. Therefore, this flow rate is calculated in advance, and a step is provided at the volume level equivalent to the amount obtained by subtracting the flow rate during tilting of the induction melting furnace from the required amount of molten metal to be poured into one mold, and as described above. By pouring the molten metal from the induction melting furnace to the step portion of the small crucible, a predetermined amount of molten metal is discharged from the small hole at the bottom of the crucible to the mold. During this period, the dispensing crucible is kept at a predetermined temperature by a heater, and the dispensing crucible is fixed and does not receive the molten metal directly from the induction furnace and is not tilted. Absent.

[0006]

【Example】

 FIG. 1 is a vertical partial elevation view of a vacuum induction melting furnace equipped with a dispensing crucible according to the present invention, and FIG. A turntable 11 is rotatably installed in a cylindrical vacuum container 10, and a plurality of (20 in this example) small molds 12 are annularly placed on the turntable 11. An induction melting furnace 14 that is arranged and tilts about a tilt axis 13 is provided, and a dispensing crucible 15 is fixed between the induction melting furnace 14 and the mold 12 to the vacuum container 10 by a bracket 10a (see FIG. 2). To be done. The outer periphery of the dispensing crucible 15 is surrounded by, for example, a carbon heater 16, and a heat insulating material 17 surrounds the outside thereof. A step portion 18a is provided on the inner wall 18 of the dispensing crucible 15 and a small hole 19a is provided on the bottom portion 19. The height of the stepped portion 18a from the bottom portion 19 is such that when the induction melting furnace 14 is tilted and the molten metal is transferred to the dispensing crucible, the molten metal poured into the dispensing crucible reaches the height of the stepped portion 18a. The sum of the amount of the molten metal flowing down from the small hole 19a and cast into the mold 12 and the amount of the molten metal at the height of the stepped portion 18a remaining in the dispensing crucible is equivalent to the required molten metal amount of one of the molds 12. Is preset to the position.

Next, the operation of this vacuum induction melting furnace will be described. The molten metal M melted in the induction melting furnace 14 is moved to a position indicated by a chain double-dashed line by tilting the induction melting furnace 14 around the tilt axis 13. When reaching, the injection into the dispensing crucible 15 is started, and the injection is continued as it is further tilted. On the other hand, in the small dispensing crucible 15, while the molten metal M is being injected, the molten metal M further flows down from the small hole 19a to the mold 12 directly below, and the molten metal level rises, so the operator monitors the situation through the peephole 20 and When the molten metal reaches the step portion 18a, the tilting is slightly returned to stop the molten metal discharge. In this state, the operation is stopped for a certain period of time and waits until all the molten metal M remaining in the dispensing crucible 15 flows down into the mold. Next, the turntable 11 is rotated to position the next mold 12 directly below the dispensing crucible 15, the induction melting furnace 14 is tilted again, and the above-mentioned work is repeated. During this time, the dispensing crucible 15 is heated by the carbon heater 16 and kept at a predetermined temperature. When replacing the mold 12 with another type having a different internal volume, a dispensing crucible corresponding to the new mold is used.

[0008]

[Effect of device]

 By setting a step in the dispensing crucible, an extremely accurate amount of molten metal is poured into multiple casting molds and there is no variation in the casting amount.Because the dispensing crucible has a small hole for tapping at the bottom, the hot water receiving part Since the tapping part can be omitted and the temperature drop of the molten metal is prevented, the yield can be improved and high quality casting can be performed.

[Brief description of drawings]

FIG. 1 is a vertical partial elevation view of a vacuum induction melting furnace equipped with a dispensing crucible according to the present invention.

FIG. 2 is a plan view taken along arrow A in FIG.

FIG. 3 is a sectional elevation view of a dispensing crucible used in a conventional vacuum induction melting furnace (second device).

[Explanation of symbols]

 10 vacuum container 11 turntable 12 mold 14 induction melting furnace 15 small dispensing crucible 16 carbon heater 18 inner wall 18a step 19 bottom 19a small hole

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location F27B 14/06 14/18 F27D 3/14 Z 7141-4K

Claims (1)

[Scope of utility model registration request] 1. An induction melting furnace capable of pouring molten metal by tilting, a turntable, and a plurality of small molds placed on the induction melting furnace in a container that maintains a vacuum or an inert gas atmosphere. In a vacuum induction melting furnace including, between the mold and the induction melting furnace, below the tilted pouring port of the induction melting furnace above the mold, the outer periphery is a heating carbon heater or the like. Surrounded by a step on the inner wall
A small dispensing crucible having a small hole in the bottom and insulated and kept warm is provided, and when the molten metal is supplied to the small dispensing crucible by tilting of the induction melting furnace, the molten metal is supplied to the mold from the small hole of the small dispensing crucible. In addition, by supplying the molten metal to the stepped portion of the dispensing crucible as it is, a fixed amount of molten metal can be supplied to each of the plurality of molds.