SU44279A1 - Hermetic shutter in electric ovens - Google Patents

Description

Nitriding of steel products due to its positive qualities with regard to the possibility of obtaining a uniform surface solid layer has a large rasprostranennaya.

For nitriding, electric furnaces with hermetically closed crucibles are usually used.

All of these furnaces make it impossible to easily open the crucible, the lid of which is screwed onto the bolts.

The invention consists in the use in a furnace for nitriding a hermetic seal, which operates according to the principle of a liquid shutter, which uses a low-melting alloy as a sealant. This latter is maintained in the molten state by a separate electrical heating element.

In FIG. 1 shows an electric furnace with the proposed valve in longitudinal section; FIG. 2 in plan.

The furnace is sovtoit from the outer iron casing 32, mounted on the squares 35. In the lower part, the casing 32 has a bottom 37 with legs. The casing and bottom are welded to ensure tightness.

(266)

Inside the casing 32 there is a laying of heat insulating heat resistant brick 34 and heat insulating backfill 3. In the laying of pz heat insulating brick 34, a nichrome resistance 27 is fixed, attached through the fireclay insulators 33 to the heat resistant frame 28-29.

The ends of the resistance 27 through the chamotte sleeves 17 are taken out to the outside, where they are connected to the hermetic clips 38, which are covered by the protective box 39. A nichrome crucible 26 is fitted with a resistance box and equipped with an ammonia supply tube 25 attached to it.

There are ears for removing the crucible 7.

From above, the furnace is covered with a metal sheet 3, having a recess on the inner side in which crucible 26 is fastened with screws 5. Asbestos pads 4 are used to cut the insulation.

The furnace is supplied with a lifting and waste w; a lid 2 with thermal insulation I and a bead 12 is installed in its direction. In the middle of the lid an engine 9 is installed

a rotary fan for the air circulation inside the crucible. The motor is hermetically sealed with the housing 10.

The cover is lifted by means of a handle 8 having, at the other end, an eccentric 13 acting on the lever 16 connected to the center of the cover. Springs 20 and 22 contain a cover in the ipodone of the half of the field.

The lever 16 is firmly connected to the rod, which enters rack 30, reinforced with bolts 36 on the stand of the outer casing of the furnace.

Such a design allows the raised lid to be easily laid aside.

Over the entire upper part of the furnace there is a bead 14 welded and bent to the outside, on the outside of which is placed a heating element 21, protected by thermal insulation 19 and closed by a casing 18. The board is filled with a fusible alloy 23 maintained in a molten state by the heating element 21.

In the curved end of the bead 14, a tube 15 is fixed with holes arranged along its length to cool the molten alloy remaining on the bead of the lid during its lifting. Cooling is performed by passing air through the openings of the tube 15.

A lid 6 for supplying ammonia and a tube 11-for its removal are placed in the lid.

The subject matter of the invention.

Claims (2)

1. Hermetic shutter in electric circuits, operating on the principle of a liquid shutter, characterized by the use of a low-melting alloy supported as a locking fluid, maintained in the molten state by a separate electrical heating element. 2. Use of a tube with air inlets in the gate according to claim 1 at the moment of raising the lid to cool the molten alloy on its sides, in order to avoid alloy falling onto the workpiece when the lid is moved to the side. fig