Preheating method for preventing cold rolling broken strip of high-grade non-oriented silicon steel

Abstract

The invention relates to a preheating method for preventing cold rolling broken strip of high-grade non-oriented silicon steel. A friction heating roller is arranged in front of a cold rolling mill, and the friction heating roller and a steel strip generate heat through friction to preheat the steel strip through a heat conduction mode; the rotating tangential direction of the friction heating roller at the contact position of the friction heating roller and the steel strip is opposite to the running direction of the steel strip, or the rotating tangential direction of the friction heating roller at the contact position of the friction heating roller and the steel strip is the same as the running direction of the steel strip but the friction heating roller and the steep strip are differentfrom each other in the running speed; and the friction heat is generated through relative movement, and the heating temperature is controlled by controlling the roughness of the surface of the friction heating roller, the running speed of the friction heating roller and the steel strip and the pressure of the friction heating roller on the steel strip. With the method provided by the invention, at ambient temperature of minus 15 DEG C to 20 DEG C, the strip breakage rate is less than 5%.

Description

technical field [0001] The invention relates to the technical field of cold-rolled non-oriented silicon steel production, in particular to a preheating method for avoiding high-grade non-oriented silicon steel cold-rolled strip breakage. Background technique [0002] Non-oriented silicon steel, especially the non-oriented silicon steel of medium grade or above, with the increase of silicon content, the plasticity at room temperature is poor, and the rolling force in cold rolling is obviously increased. Yield and production efficiency of silicon steel cold rolling process. [0003] Using twenty-high Sendzimir rolling mill for cold rolling and preheating the steel strip before cold rolling is an effective method to reduce the rate of strip breakage, provided that the steel strip must be heated above the ductile-brittle transition temperature. Steel strip preheating methods include: 1. Water bath heating. This method is to put the steel coil as a whole into hot water for heati...

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Problems solved by technology

Therefore, the heating time of this method is longer

In addition, because hot water is used for heating, it cannot be heated to a higher temperature, and there is nothing that can be done to the steel whose brittle transition temperature is close to 100 degrees; 2. Induction heating, this method is to use the eddy current heating steel strip formed by high-frequency AC power supply, the existing problems, First of all, this method requires a large current and has high requirements on the power grid; secondly, because high-grade silicon steel silicon steel contains high silicon, it has a greater effect on suppressing eddy currents, so the heating efficiency of this method is low; thirdly, this method needs to be increased. frequency power supply and other equipment, the capital investment is relatively high; in addition, this method also requires a large space to store equipment

3. Flame heating, that is, the open flame heating method of pure oxygen plus coal gas in recent years, existing problems: First, the flame directly heats the steel strip, and it is easy to cause the steel strip to oxidize under the action of pure oxygen

Second, changes in gas pressure can easily cause changes in the flame core to affect heating efficiency

The third is to increase the heating efficiency. This method adopts the method of rolling the steel strip to more distributed burners. If there are operations such as breaking and changing the leader belt, the burners need to be lifted up, which is difficult to operate.

Fourth, a larger site is required to store equipment, and existing rolling mills cannot be installed if there is no reserved space

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