RU2810432C1 - Method for regulating rotation speed of ball mill rolls - Google Patents

Abstract

FIELD: rolling mill.

SUBSTANCE: method for rolling balls in the stand of a ball rolling mill. Provide a reduction in the rotation frequency of ball mill rolls with flanges by 20-50% of their operating frequency depending on the diameter of the rolled workpiece, gripping the workpiece with ball mill rolls, increasing the rotation speed of ball mill rolls to their operating frequency and reducing the specific contact pressure on the ball rolling flanges in the gripping zone rolls. Regulation to reduce or increase the rotation speed of ball mill rolls is provided in automatic mode by monitoring the position of the workpiece using two sensors. One of the sensors is located before the workpiece enters the operating zone of the ball mill rolls, and the other is located at the exit from the ball rolling mill stand. The specified increase in the rotation frequency of the ball mill rolls to their operating frequency is carried out after the workpiece is captured by the ball mill rolls, the start of its rotation and the passage of one working revolution of the ball mill rolls.

EFFECT: as a result, the service life of ball mill rolls increases.

1 cl, 1 dwg, 1 ex

Description

The invention relates to rolling production, in particular to methods for regulating the rotation speed of the rolls of a ball rolling mill.

There is a known method and device for equalizing moments on the working rolls of a rolling stand with an individual electric drive [1] (patent RU No. 2362641, MPK V21B37/46, published on July 27, 2009), including issuing a task for the rotation speed of the electric drives of the working rolls, comparing the moments for the upper and lower rolls, obtaining moment mismatch, issuing correction for a limited change in the rotation speed of the rolls if the permissible moment difference is exceeded. The advantage of the method is that to determine the correction for moment equalization, only the integral components of the roll speeds are used and only the rotation speeds of the electric drive of the most torque-loaded roll (upper or lower) are adjusted in turn, while the corrections are always aimed at reducing the electric drive torque of the most loaded roll.

The disadvantage of this invention is that this technology is applicable only to mills with individual roll drives.

There are known methods where variable roll frequency is used to equalize roll speeds online, in multi-stand mills to ensure minimal traction forces in the metal during uneven heating of the metal along the length [2] (RU patent No. 2075358, IPC B21B37/46, published 03/20/1997 ), or for stands with individual roll drives, patent RU No. 2362641, IPC B21B37/46, published on July 27, 2009 [1] to increase the stability of the rolling process at high speed, achieve high mill productivity and reduce the sorting of cold-rolled steel based on surface defects.

The disadvantage of this invention is that this technology is applicable only for multi-stand mills; ball rolling mills, in turn, are single-stand.

The closest (prototype) in technical essence to the claimed device, in terms of the number of similar features, is a method for regulating the rotation speed of rolls of ball rolling mills [3] (patent RU No. 2723342, IPC V21N1/14, published 06/09/2020, Bulletin No. 16) where An increase in the durability of the flanges of ball rolling rolls is ensured by the fact that in the period between rolling the workpiece and gripping the subsequent workpiece, when the load drops, the rotation speed of the rolls is reduced to 20-50% of the operating frequency, depending on the diameter of the rolled workpiece and the characteristics of the mill, and after gripping the subsequent workpiece and the appearance of the roll torque, the roll rotation speed is increased to the operating frequency, while the roll rotation speed is controlled automatically depending on the fixed load using a logical code.

The disadvantage of this invention is that the technology takes into account the change in the rotation speed of the rolls when gripping the workpiece only due to the appearance of a moment on the roll and its removal, but does not take into account the possibility of using other tracking systems when gripping the workpiece.

The technical result to which this invention is aimed is to increase the service life of ball rolling rolls through the use of technology for changing the rotation speed at the moment of gripping.

The specified technical result is achieved due to the fact that the method of regulating the rotation speed of ball rolling rolls of a ball rolling mill, including reducing the rotation speed of rolls 1 to 20-50% of the operating frequency, depending on the diameters of the rolled workpiece 2 and the characteristics of the ball rolling mill, and after gripping the subsequent workpiece 2 increase the rotation speed of the rolls to the operating frequency, after which in the gripping zone the specific contact pressure on the flanges of the ball rolling rolls is reduced; in accordance with the invention, automatic control is carried out to increase or decrease the rotation speed of the rolls, monitoring the position of the workpiece 3 using sensors 3.

In addition, automatic control to increase the rotation speed of the rolls is carried out after the start of its rotation and the passage of one working revolution of the rolls.

In addition, automatic control to reduce the rotation speed of the rolls is carried out automatically after monitoring the loss of the last half of the ball from the ball rolling mill using ball counting sensor 3.

In addition, a non-contact or contact sensor for monitoring the position of objects is used as position sensor 3.

According to the proposed method, it is proposed to control the rotation speed of the rolls in automatic mode depending on the input from the workpiece position sensors and the ball counting sensor. After rolling the workpiece, when the last half falls out of the mill stand, reduce the frequency of rotation of the rolls by 20-50% of the working one, depending on the diameter of the workpiece being rolled and the characteristics of the mill, and after grabbing the next workpiece, begin its rotation and complete one working revolution of the rolls, increase to working level (FIG 1). This will ensure a drop in the specific contact pressure on the most worn flanges (in the gripping zone) and will increase the service life of the rolls by up to 20%.

The technical essence of the invention is illustrated by the drawing, which shows:

FIG.1. Presence and location of sensors when gripping a workpiece

Description of reference position numbers:

1- Ball rolls

2- workpiece

3- workpiece (ball) position sensors

The essence of the proposed method is carried out as follows. During the rolling of balls, the greatest wear occurs along the flanges of the rolls, in particular in the workpiece gripping area. Based on the condition of gripping the workpiece, the determining parameter is the circumferential acceleration Ω. On operating ball rolling mills, the workpiece is placed into rolls with zero circumferential acceleration and rotation is imparted to it by the rolls after gripping, so the acceleration will be the square of the speed. Because of this, the greatest pressure falls on the flanges where the rolls grip the workpiece. Depending on the diameter of the workpiece, the diameter of the rolls and other parameters, a slight decrease in the rotation speed of the rolls can lead to a significant decrease in the specific contact pressure on the rolls in the gripping zone. In a stable process, the specific contact pressure on the rolls changes insignificantly when the rotation speed changes.

Example.

The proposed method was tested and implemented on the ball rolling mill of the rail and beam shop of JSC EVRAZ Nizhny Tagil Metallurgical Plant.

When producing a ball with a nominal diameter of 100 mm, billet 2 with a nominal diameter of 100 mm and a length of 6.5 m is used. Billet 2 is heated in a furnace to a temperature of 1040⁰C and placed in the axial direction into the working stand of a 60-120 KOCH AMT ball rolling mill, with ball rolling rolls 1 nominal diameter 700 mm. In this case, the rolls rotate into the cage at a frequency of 75 rpm before the task. Before the workpiece enters the roll operation zone, it passes through a non-contact optical position sensor (DOG-M18-76K-1113-SA), after which the signal from the sensor enters the logic circuit of the thyristor converter, and the logical time relay begins to operate, which is designed for gripping the workpiece and passing one rotation of the roll after gripping, after which the return signal is automatically transmitted and the rotation speed of the rolls increases to 100 rpm. The entire workpiece is rolled. A non-contact optical sensor (DOG-M18-76K-1113-SA), located on the back side of the rolls - at the exit from the stand, transmits a signal about the number of balls dropped from the workpiece, the ball count counts 86 full balls, which means the completion of rolling the entire workpiece, and transmits a signal to the converter to automatically slow down the rolls to 75 rpm. After which the next workpiece is set and the cycle repeats again

Analysis of patents and scientific and technical information did not reveal the use of new essential features used in the proposed solution for their functional purpose. Therefore, the proposed invention meets the “inventive step” criterion.

It has been confirmed that the use of this invention gives the following effect:

- with the use of this technology, the service life of rolls on the 60-120 RBC mill, equipped with position sensors, was increased by an average of 10%;

- it is proposed to use variable rotation speed with automatic adjustment depending on the position of the workpiece in the mill.

Information sources

[1] Patent RU No. 2362641, IPC V21B37/46, published 07.27.2009;

[2] Patent RU No. 2075358, IPC B21B37/46, published 03/20/1997;

[3] RU patent No. 2723342, IPC V21N1/14, published 06/09/2020, bulletin No. 16.

Claims (3)

1. A method of rolling balls in a ball rolling mill stand, including reducing the rotation frequency of ball rolling rolls with flanges by 20-50% of their operating frequency depending on the diameter of the workpiece being rolled, gripping the workpiece with ball rolling rolls, increasing the rotation speed of ball rolling rolls to their operating frequency and reducing in the roll gripping zone, the specific contact pressure on the flanges of the ball rolling rolls, characterized in that regulation to reduce or increase the rotation speed of the ball rolling rolls is provided automatically when monitoring the position of the workpiece using two sensors, one of which, which is a workpiece position sensor, is placed before the workpiece hits to the operating zone of the ball rolling rolls, and the other, which is a counting sensor of the rolled balls, is at the exit from the ball rolling mill stand, while the specified increase in the rotation speed of the ball rolling rolls to their operating frequency is carried out after the workpiece is captured by the ball rolling rolls, the start of its rotation and the passage of one working revolution ball rolling rolls. 2. The method according to claim 1, characterized in that after monitoring the loss of the last half of the ball from the ball rolling mill, regulation is carried out to reduce the rotation speed of the rolls in automatic mode using a ball counting sensor. 3. The method according to claim 1 or 2, characterized in that a non-contact or contact sensor for monitoring the position of objects is used as a workpiece position sensor.