SU1659139A1 - Method of asymmetric rolling in stands with individual roll drives - Google Patents

Abstract

This invention relates to rolling production. The purpose of the invention is to increase productivity by imparting a predetermined curvature and bending direction to the front end of the rolled stock by stabilizing the speed asymmetry of the rolls. The goal is achieved by preloading the rolls with moments equal to the moments during the established rolling process, which allows stabilizing the magnitude of the speed asymmetry when the strip is caught by the rolls and obtaining the specified curvature of the front end, thereby eliminating the bandwidth and reducing the stands. 1 il.

Description

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The invention relates to rolling production and can be used for asymmetric rolling in cages with individual drive rollers.

The purpose of the invention is to increase productivity by imparting a predetermined curvature and bending direction to the front end of the rolled stock by stabilizing the speed asymmetry of the work rolls.

The drawing shows the kinematic and power parameters of the work rolls in the capture strip, where 1.2 is the angular velocity of the upper and lower work rolls, with 1, 3 - the value of the speed asymmetry. work rolls,%; 4, 5 - moments on the upper and lower engines, MNm; 6, 7 - moments of technological resistance forces (rolling moments) on the upper and lower

rolls, MNm; 8 - the required value of the speed asymmetry of the work rolls. %

Preloading the work rolls with moments equal to the rolling moments in stationary conditions of asymmetric rolling leads to the same phenomena that are observed during the period of metal capture by rolls, namely uneven due to the different elastic-mass parameters of the main drive transmissions of the upper and lower working wheels. rolls decrease their speed and, consequently, the deviation of the value of the speed asymmetry from the set. The beginning of the capture of the strip is made to eliminate the influence of deviations of the speed asymmetry from the given on the nature of the flow of the technological process during the formation of the front end of the roll

ABOUT

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When the speed asymmetry of the work rolls reaches a predetermined value and stabilizes, the process of metal capture by the rolls begins.

The process of filling the deformation zone and the formation of a rigid front end is accompanied by an increase in the moment of resistance on the work rolls. In order for this process to take place at a constant value of the moment of resistance on the work rolls, the oscillation of which adversely affects the magnitude of the speed asymmetry, the preloading moment is reset at a speed equal to the rate of increase of the rolling moment. Thus, the process of metal capture by rolls and deformation of the front end of the strip takes place under conditions as close as possible to steady-state, the fluctuation of the speed asymmetry of the work rolls is eliminated and the shape of the front end of the roll is stabilized.

Example. The strips 10.9x2340 from 09PFB steel were rolled in the finishing stand of mill 3000.

Before the start of rolling, the total rolling moment and its distribution between the driving (rotating at a higher angular velocity) and driven rollers is determined.

For the strip under consideration, the total rolling moment is equal to 1.472 MNm, on the leading roll - 0.774 MNm, on the driven roll - 0.7 MNm (curves 6.7), at their rotational speeds, respectively, 9.5 and 8.75 s.

After reversing the rolls and accelerating them at idle to the required speed, the work rolls load with braking torques to the given values. When the work rolls are loaded, the rotational speeds of the motor cores decrease, the current and driving moments increase (curves 1, 2, 4, 5). However, due to the different rigidity of the transmissions of the main drive of the work rolls. (stiffness of the upper St 0,723-10 ° Nm / rad of the lower Cn 0, Nm / rad) the speed drop of the upper and lower rolls is different

(curves 1, 2), which leads to a deviation of the value of the speed asymmetry from the given one (curve 3). The speed sensors measure the speeds of the work rolls and compare them. As soon as the fluctuation of the magnitude of the speed asymmetry is stabilized, i.e. the difference between the previous and subsequent measurements does not exceed the permissible value;

metal rolls and reset braking torque. In this case, this happens in 0.5-0.6 s (curve 3).

So that the work roll overload interval does not mention the kinematic parameters of rolling, the braking torque decays at a speed equal to the rolling torque moment growth. In this case, the value of the speed asymmetry preserves the given (or close to it) value and.

therefore, the curvature and direction of bending of the front end of the roll are within a predetermined interval.

Claims (1)

The proposed method makes it possible to stabilize the magnitude of the speed asymmetry at the time of the formation of the front end of the roll and to obtain the specified value and direction of its bending, to eliminate strip cleaning, to reduce mill stalls. Invention Formula Method of asymmetric rolling in cages with an individual drive of rolls, including preliminary determination of rolling moment, loading of working rolls and measurement of their speeds rotational speed setting, asymmetry of the rolls, characterized in that, in order to increase productivity by imparting a given curvature and bending direction to the front end of the rolling stock by stabilizing the speed asymmetry of the work rolls, prior to the start of rolling, the rolls are loaded to a value equal to the rolling moment on each of them, and after the metal task of the rolls, the preload loading times are reduced with a speed equal to the rolling moment growth speed on the respective rolls. “O s-N 001 w eion s C “O Cb cb4