SU968082A1 - Method for heat treating magnetic circuits - Google Patents

Description

(54) METHOD OF THERMAL PROCESSING OF MAGNETIC WIRES

one

The invention relates to metallurgy, in particular, to methods of heat treatment of sheets of magnetic conductors of electrical steel used in mechanical engineering and electrical engineering.

In modern engineering and electrical engineering, low-carbon steels are used to manufacture the magnetic circuits of electric motors, the thermal treatment of which consists in annealing and oxidation.

A known method of heat treatment of magnetic core sheets of low carbon steel, which consists in annealing them at 750-950 ° C in carbon dioxide-purified to less than 4% and dried to the dew point (+5) - (+ 10) ° C exothermic controlled atmosphere containing up to 0, carbon monoxide, up to 1% hydrogen, aged at this temperature, controlled cooling followed by thermovalent oxidation in a separate chamber at an initial temperature of 480-520 ° C and 380-420 ° C at the end of the oxidation process

The disadvantages of this method are the use of an exothermic atmosphere, purified from carbon dioxide to a content of less than 4 / o, the use of additional electrothermal equipment to perform thermal air oxidation, increased consumption of carbon gases for the preparation of an exothermic controlled atmosphere, increased consumption of electricity per unit of output and the inability to conduct a regulated process of oxidation. The closest to the proposed

10 of the technical essence and the achieved effect is a method of heat treatment of magnetic conductors made of electrical steel, including annealing at 750-950 ° C and oxidation in a controlled atmosphere, while annealing and oxidation are carried out in a continuous process in one chamber with a controlled atmosphere of 0.5- 2% carbon monoxide, 4.2-8% carbon dioxide, 1-2% hydrogen, nitrogen - the rest, with humidity (-10) - (+ 20) ° С with

2 changes in carbon dioxide from 4.2 to 8% and humidity (-10) - (+ 20) ° С 2.

The disadvantages of this method are the use of hydrocarbon gas (methane, propane-butane, etc.) to prepare an exothermic controlled atmosphere, the use of special equipment for preparing an exothermic controlled atmosphere, increased costs of electricity per unit of production, the use of production space to accommodate equipment for the preparation exothermic controlled atmosphere.

The purpose of the invention is to reduce the consumption of hydrocarbon gas by using waste oxygen produced from technical nitrogen and carbon dioxide.

To achieve this goal, sheets of magnetic carbon steel, including electrical, magnetic cores are heated to a temperature of 750-950 ° C, annealed and oxidized, and annealing and oxidation are carried out in a continuous process in one chamber with a controlled atmosphere of% -97% nitrogen, 0 , 2-1% carbon dioxide, the rest is oxygen, at a humidity of 40–20 ° C at the beginning of the process and (-40) - (-50) ° C during the period of exposure and slow cooling.

Example. The process of heat treatment of the stator sheets of electric motors of the 4A series made of steel 2013 or 2011.

Lightly unfolded sheets of magnetic cores placed on mandrels in special pallets are loaded into a passing-through roller-bed furnace consisting of an oil kiln, a heating chamber, an extract and a controlled cooling. After oil is burned, the sheets enter through the prechamber into the heating chamber, holding and controlled cooling, where heating, exposure, controlled cooling and oxidation are carried out in a continuous process in an atmosphere containing 96-97% nitrogen, 1% carbon dioxide, the rest is oxygen and humidity, corresponding to a dew point temperature of + 40 ° C in the heating zone and (-40) - (- 50) ° C in the exposure and controlled cooling zones, with carbon dioxide being supplied to the exposure zone in order to control the thickness of the oxide film on the treated products. Then, through the prechamber, the magnetic core sheets enter the accelerated chamber.

cooling with air, where they are cooled to room temperature.

Using the proposed method of heat treatment of sheets of low carbon steel magnetic cores provides, in comparison with the known, saving of hydrocarbon gas (methane, propane-butane, etc.) used to prepare an exothermic controlled atmosphere, the use of waste oxygen

0 production (technical nitrogen and carbon dioxide) to obtain a controlled atmosphere, there is no need to use special equipment for preparing an exothermic controlled atmosphere, saving production space, reducing energy consumption per unit of processed products, reducing operating costs and reducing water consumption used to cool electrothermal equipment .

The economic effect of using the proposed method is 163.3 thousand rubles. in year.

Claims (2)

1. USSR author's certificate number 475400, cl. C 21 D 9/46, 1975. 2. USSR author's certificate for application number 2714369/02, cl. C 21 D 1/74, 1978.