RU2211126C2 - Method for restoring rotor of exhaust fan - Google Patents

Abstract

FIELD: machine engineering, namely restoration of machine parts such as rotors of exhaust fans. SUBSTANCE: method comprises steps of cutting off two arranged diametrically opposite blades in each half of disc in order to form in each disc half two diametrically opposite windows; placing in each window two screw braces for regulating clearance between disc and covers of impeller; then cutting out at one side of each window one additional blade and arranging at opposite side of each window one new blade by of tack welding of it; repeating cycle for cutting out and arranging one new blade in each window until removing all worn blades; arranging in each window two last new blades by tack welding of them; after arranging all blades welding them around by continuous welded joint; realizing tack welding and welded joints by means of gas-shield welding with use of austenite wire. EFFECT: elimination of heat treatment procedure at keeping geometry parameters of impeller, prevention of welding flaw occurring. 3 cl, 3 dwg

Description

 The invention is used in the mining industry. The exhauster is designed to suck air through the mixture and remove combustion products formed during sintering of the sinter. The exhauster rotor (see FIG. 1) has a shaft 1 and an impeller 2 mounted on it. The latter consists of a central disk 3 and two tires 4 with blades 5 welded to them, as shown in FIG. 1. During operation, the rotor blades quickly - after a few months - wear out and an expensive product (~ 1 million rubles) is sent to scrap.

The prior art. The replacement of worn blades with new ones in order to extend the service life of the rotors was not performed for the following reasons:
- According to the conditions of the Nevsky Plant manufacturing rotors, after welding, the impeller must undergo high-temperature processing, which cannot be carried out together with the shaft without spoiling the latter.

 - When cutting out worn and welded new blades, welding deformations reduce the clearance between the central disk and tires, i.e. make the wheel width uneven along the circumference.

 The closest analogue of the invention is a method of restoring the impeller of an exhauster, which provides for the separation of worn blades from the disk of the wheel and installation instead of them and fixing by welding new blades (RU 156682 C1, B 23 K 6/00, 09/27/2000). Its disadvantage is that it does not provide for the solution of the above issues: how to abandon post-weld heat treatment and how to prevent distortion of the impeller geometry by welding deformations.

 An object of the present invention is to restore an exhauster rotor by replacing worn blades with new ones without subsequent heat treatment and without distorting the impeller geometry with welding deformations.

 The task is achieved as follows. Two blades (1 and 2 in FIG. 2) are cut diametrically opposite in each half from the central disk, i.e. Only eight blades. This forms two diametrically opposite windows in each half (from the central disk). Two screw spacers 3 are installed in each of these four windows to control the clearance between the central disk and the tires. Then, one additional worn out blade is cut from one edge of the windows (4 — in FIG. 3), and one new blade 5 is installed on the welding edges of the windows from the opposite edges of the windows. The cycle — cutting out the worn out blade and installing a new one — continues in each of the four windows with the movement of tacks as the windows move in any one direction (for example, in the direction of the arrow in FIG. 3), until all old blades are removed. Then the last two new blades are installed on the tacks in the windows. After installing all the blades, they are scalded with a continuous seam.

 Welding the blades with a continuous seam should not be done immediately as they are installed, because this increases the reduction in clearance in the windows between the central disk and tires from 2 mm to 8 mm, which becomes impossible to eliminate with screw spacers.

 So that the rejection of the post-welding high-temperature heat treatment does not lead to the formation of cracks in the welded joints, the welds are made of austenitic steel.

Example. The rotor of the exhauster of the Kachkanarsky GOK with a diameter of ⌀2735 mm with a central disk made of steel 40X and tires made of steel 45 was repaired by the above method. Blades of steel 45 were welded (both with tacks and a continuous seam) by a semiautomatic device, wire SV-08X21N9G7T in a medium of СО ₂ . Production tests have shown that the service life of a repaired rotor is the same as that of a new one.

Claims (3)

 1. A method of restoring an exhauster rotor, comprising separating worn blades from the impeller disk, installing and fixing by welding new blades instead of them on the disks, characterized in that two blades are cut off diametrically opposite in each half of the disk, forming in each half of the impeller two diametrically opposite windows, two screw struts are installed in each of the windows to control the clearance between the disk and the tire covers, then one additional cut out from one edge of the windows the blade, and from the opposite edge of the windows, one new blade is installed on welded tacks, the cutting and installation cycle on the tacks one new blade is repeated in each window until all worn blades are removed, then the last two new blades are installed on the tacks , after installing all the blades they are scalded with a continuous seam.  2. The method according to p. 1, characterized in that cutting off two blades in each half of the disk, remove eight blades, forming four windows in the impeller.  3. The recovery method according to claim 1 or 2, characterized in that the tacks and seams are welded in shielding gas by an austenitic wire.

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