SU1435338A1 - Method of feeding tubular billet to pilger mill - Google Patents

Abstract

The invention relates to the processing of metals by pressure, in particular to methods for the production of hot-rolled pipes in pilger mills. The aim of the invention is to increase productivity. The essence of the method lies in the magnitude of each feed. Before each feeding into the rolls of the billet, its diameter is measured in the annular region to be rolled. From the measured workpiece diameter, the area of its cross section is calculated. The value found is compared with the area in the previous measurement. In proportion to the change in the cross-sectional area, the value of the next feed changes from the previous one. The application of the proposed method allows to increase productivity and increase the durability of pilgerstan. 1 il. with S (L

Description

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The invention relates to the processing of metals by pressure, in particular to methods for the production of hot-rolled pipes in pilger mills.

The purpose of the invention is to increase productivity.

The drawing shows the device implementation of the proposed method.

The device contains an optical meter 1 of the billet diameter connected to one control input of timer 2 and one of the inputs of the arithmetic unit 3, the second input of which is connected to the output of memory block 4, and the last input to the output of the timer. The output of the arithmetic unit 3 is connected to one of the inputs of the comparison unit 5, to the second input of which the displacement meter 6 is connected. The output of the comparison unit 5 is electrically connected to the input of the control unit 7, and the output of the latter is connected to the input of the actuator of the hydraulic drive 8 of the feeder 9.

The optical diameter meter 1 is set at such a distance from the center line of the rolls 10 that, after each rollback of the tubular billet P to the rearmost position in the measurement plane, there is a ring-shaped portion of the billet that will be crimped and rolled out in the next rolling cycle, i.e. the distance from the center line of the rolls MN to the plane of the AV measurement is expressed by the formula

    / L1LN

where lonr is the distance from the line of centers MN to the plane of measurement of the diameter of the backing box;

1 - distance from the plane

DC, in which the beginning of the piligram head after a rollback occurs, to the center line MN;

m. .. - the minimum amount of podMU and

chi allowed for this pipe mix

The cells of the memory block, the numbers of which correspond to the time elapsed since the beginning of the process, store corrections to the feed rate that take into account the state of the workpiece,

The control unit contains a powerful transistor switch and an electromagnetic relay, the winding of which is turned on

0 5 0 5

five

0

H

0

five

0

into the collector circuit of the transistor switch a,

The method is carried out as follows.

At the moment when the tube blank 11 appears in the diameter measurement plane (AB), the signal from the optical diameter meter 1 starts a timer 2, which begins to count the elapsed time from the beginning of the rolling process of the blank. According to the indication of the timer at a given time, a corresponding temperature correction to the feed rate is selected from memory block 4. After a rollback, when the tubular billet is in the extreme back row, the signal from the optical diameter meter arrives at the input of the arithmetic unit 3, to another input of which is supplied from the memory cell slot, the number of which is equal to the time counted by the timer by this time and expressed in seconds , digital code of temperature correction to the amount of feed. After that, the arithmetic unit 3 calculates the value of the next feed by the formula

t t, + d- - uj, where m, is the value of the feed in the i-th cycle rolling; t - constant feed rate,

typical for this pipe sourcing |

 an amendment that takes into account the random nature of the change in the diameter of the billet during the rolling process (calculated before each next feed according to the measured diameter);

  an amendment that teaches a drop in the temperature of the workpiece by the end of the rolling process (taken from experimental data),

The result of the calculation goes to block 5 of the comparison. At the time of returning the workpiece and transferring it beyond the center line, the signal from displacement meter 6 also begins to arrive. When the magnitude of the signal from the displacement meter is compared with the magnitude of the signal specified by the arithmetic unit, a control signal is generated in the cp unit in the form of a positive polarity level, which is.

The rod is kept at the output of the comparator unit until the workpiece reaches the extreme rear position. The control signal enters the control unit 7, where it opens the transistor switch, and the collector current of the transistor begins to flow in the winding of the electromagnetic relay. The relay contacts included in the supply circuit of the winding of the executive device of the hydraulic drive 8 of the feeding device 9 break the power circuit and de-energize the winding of the actuator of the hydraulic drive. Feed is stopped. After that, the deformation and movement of the metal begins (rollback of the workpiece). When the extreme rear position of the workpiece is reached, the comparison unit returns to its initial state (a zero voltage level is established at its output), the power supply circuit of the actuator winding of the hydraulic actuator is closed and the cycle of operation of the entire device is repeated .

Example: When rolling a general purpose pipe with a diameter of 21.9 mm and a wall thickness of 12 mm, the feed rate is taken to be 22.4 m, and the external diameter of the workpiece is 375 - 380 mm,. Production surveys show that during the steady state process rolling thickness of the workpiece is randomized as a result of the action of longitudinal forces on the side of the feeder. As a result, at the initial part of the workpiece, the outer diameter remains equal to 375 mm, and in subsequent sections it reaches 385 mm. At the same time, the performance while maintaining the required surface quality of the pipe is maximum when the workpiece is rolled out at a site with a diameter of 385 mm. The volume of the rolled portion of metal

n i j2

V, iiJ - 2J 6708179.8 mm

where V is the volume of the serving portion

metalj

m is the feed rate; D is the external diameter of the billet, which varies during the rolling process; d is the internal diameter of the pipe

billet, which is practically unchanged; S is the cross-sectional area

blanks,

 areas of the workpiece, where the outer diameter is the smallest and equal to 375 mm, the volume of the pickup portion of the metal

Dl - d

- 6173208.3 mm

V., .-

Therefore, in the area of the workpiece with the smallest diameter, the productivity is underestimated by 7-8%,

To maintain maximum productivity Rolling along the entire length of the workpiece, it is necessary to increase

the feed rate in the initial areas to 24.4 mm and reduce it in proportion to the change in diameter and the temperature drop of the workpiece, brought in areas with a diameter of 385 mm to 22.4 mm,

The application of the proposed method makes it possible to choose the optimum feed rate for each rolling cycle, which will increase the productivity of mercury in comparison with the known method, eliminate possible overloading of parts and components of the rolling equipment, and consequently, increase its durability.

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Claims (1)

Invention Formula The method of feeding pipe billet. in Pilgerstan, which includes moving the workpiece to the rolls to a predetermined feed rate with a decrease in the steady state process, characterized in that, in order to increase productivity, the outer diameter of the workpiece is measured in a plane spaced from the beginning of the pilim head on each a distance not exceeding the value of the previous feed, and the change of the next feed is made proportionally to the change in the cross-sectional area of the workpiece as compared with the previous measurement. L L. m 0 L to D N