JPH0447599Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a gate valve for a vacuum furnace such as a vacuum induction melting furnace.

[Prior Art] A vacuum furnace such as a vacuum induction melting furnace is a device that induction-heats a material to be melted in a vacuum or an inert gas atmosphere and casts it into a mold or the like.

As shown in FIG. 4, a conventional vacuum induction melting furnace includes a carbon crucible 1, a molten metal 2 stored therein, a back stamp material 3, a tap hole 4, a tilting shaft 5,
Mold 6, induction coil 7, furnace tilting mechanism 8, material addition bucket 9, gate valve 10, bucket lifting mechanism 1
1. Material insertion door 12. Vacuum pump (not shown)
Connecting portions 13, 13 communicating with evacuation paths such as
', a vacuum chamber 14, and a door 14'.

The gate valve 10 is provided with a through hole through which the material addition bucket can pass, and although this through hole is normally closed, it can be opened when necessary to allow the bucket to move up and down. There is. In addition, a gate valve 10, a bucket lifting mechanism 1
1. Material insertion door 12, vacuum exhaust system connection part 13'
This constitutes a raw material input chamber 15.

When it is desired to perform semi-continuous melting work in this vacuum furnace, in order to introduce the material to be melted into the induction furnace without breaking the vacuum, the above-mentioned partition is used to shut off the vacuum inside the vacuum chamber 14 and the atmosphere. Valve 10 is required.

First, in the atmosphere, in a bucket 9 with an open bottom lid,
The material to be melted is placed in the raw material input chamber 15 and fixed to a bucket lifting jig, the chamber is evacuated, the valve 10 is opened, the bucket 9 is lowered under vacuum, and the bottom cover is opened. The material is put into the furnace as follows.

In this way, the material to be melted is set in the induction furnace and heated by induction to form a molten metal.

[Problem to be solved by the invention] By the way, when the molten metal is Fe-Ni, the temperature reaches over 1500℃, and the gate valve located directly above the furnace, that is, above the molten metal, receives heat side radiation and the sheet surface is heated. Ru. If this condition continues and the operation continues, the sheet surface will become thermally distorted and a vacuum leak will occur.

In addition, there are examples in which a shielding plate is placed to shield the molten metal from heat, but this is not preferable because of sudden side radiation when the shielding plate is opened and closed, and heating due to the atmosphere in the furnace.

Furthermore, there are some cases in which refractories are installed on the lower surface of the sheet (the part facing the furnace), but if the refractories are damaged, they may get mixed into the molten metal, and maintenance related to replacing the refractories is difficult.

Note that damage to the refractory refers to damage caused by the evaporation of impurities from the molten metal, bumps during gas evaporation, damage caused by the impact of molten metal splash due to bumps during material injection, and cracks due to heating and cooling of the refractory.

[Means for Solving the Problems] The present invention solves the above-mentioned problems of the conventional method by providing a water-cooled structure for the vacuum chamber and the gate valve located almost directly above the induction furnace disposed in the vacuum chamber. To provide a gate valve for a vacuum furnace that has a seat surface of the gate valve with less thermal distortion, can be used stably for a long period of time, does not generate vacuum leakage, and can withstand the impact of molten metal splash. purpose.

[Example] The present invention will be specifically described below with reference to an example shown in FIG. In the same figure, components equivalent to those in FIG. 4 are designated by the same reference numerals.

In FIG. 1, 16 is a vacuum pump for evacuating the vacuum chamber 14, 17 is a vacuum pump for evacuating the raw material input chamber 15, 18 and 19 are vacuum valves, and 20 is a check valve.

Second, as shown in an enlarged view of its internal structure, the gate valve 10 of the present invention has a double jacket structure, and a water passage H is formed in the middle part. The passage H has a flow path formed so that the cooling water can flow efficiently, and a flow plate may be attached thereto.

In addition, as shown in FIG. 3, the valve body 10A has:
an inlet/outlet 10b for supplying cooling water from the outside;
10c, and a fixing member 10d is provided for continuous feeding to the air cinder 21.

Driven by an air cylinder 21 which is an opening/closing means for the gate valve 10, it moves horizontally (in the X direction) and presses the O-ring 22 fixed to the connecting portion 10 of the valve with a downward force (in the Y direction). There are various methods for generating this force in the Y direction, but they will be omitted here.

If the induction furnace weighs about 10 kg, it is possible to feed the material from the tank side of vacuum chamber 1, but it is difficult to successfully feed material that weighs more than that into the furnace, so most of the material must be fed from the top of the furnace. I'm going.

[Operation] In the case of a vacuum furnace equipped with the gate valve of this proposal,
Even if the valve body is heated by secondary radiation heat transfer from the molten metal that has been inductively melted, the temperature of the valve body does not rise because the cooling water is efficiently cooled within the double structure jacket, and the temperature of the valve body remains constant. maintained at temperature.

As a result, the occurrence of distortion due to side radiation heat has almost completely disappeared.

Next, molten metal balls flying off the molten metal may collide with the valve seat surface directly above the furnace. There are cases where the hot water balls scatter, become pseudo-hardened and solidified on the sheet surface, and become non-adhesive. In these cases, when a gate valve is used in a semiconductor field, the distance between the surfaces (gear G) is small, making it impossible to open the valve.

In the vacuum furnace of the present invention, by widening the distance G between the surfaces and opening it by 5 mm or more according to the results of the examples, smooth opening and closing operations can be performed, and maintenance is easy and cleaning is also easy. It has been confirmed that.

[Effects of the invention] According to the invention, the gate valve seat surface adopts a water-cooled structure and the gap G is widened, thereby almost eliminating thermal distortion due to secondary radiation of molten metal heat, eliminating troubles caused by molten metal scattering, and providing long-term service life. Overall, it has excellent features such as improved safety and reliability, and no need to worry about vacuum leaks. Further, by setting the distance G between the surfaces to 5 mm or more, maintenance management can be made easier.

[Brief explanation of the drawing]

FIG. 1 is a vacuum system diagram of the vacuum furnace of the present invention, FIG. 2 is an enlarged vertical view showing the structure of the seat surface of the gate valve in detail, and FIG. 3 is a plan view of the seat surface. Also,
FIG. 4 is a longitudinal sectional front view showing a conventional example. 1... Crucible, 10... Gate valve, 10A... Valve body, H... Cooling water passage, 10b, 10c... Cooling water inlet/outlet, 14... Vacuum chamber, 15... Raw material input chamber, 21... Air cylinder.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A gate valve provided between a vacuum chamber and a raw material input chamber located almost directly above an induction furnace installed in the vacuum chamber has a double jacket structure,
A gate valve for a vacuum furnace, characterized in that a water passage is formed in the intermediate portion, and cooling water is supplied from the outside. 2. The gate valve for a vacuum furnace according to claim 1, wherein the gap between the valve surface and the flange when the valve body of the gate valve moves is at least 5 mm or more.