RU2551728C2 - Cold intermittent rolling of super-thin pipes - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: this process comprises clamping the pipe billet tail part by feed chuck and turning it to deformation zone. Pipe billet is rolled and rolled pipe is displaced inside drawing chuck unless the latte gets to its extreme position. Pipe billet tail part is released to clamp rolled pipe by drawing chuck arranged at the mill outlet side. Pipe billet is additionally rolled whereat pipe is drawn for drawing chuck feed amount at displacing in rolling direction. Drawing chuck is displaced by servo drive, chuck displacement rate being equal to that of pipe elongation at rolling. Said additional rolling of pipe billet is performed timed with the next pipe billet feed to deformation zone. Turn of additionally rolled pipe is also timed with the turn of next pipe.

EFFECT: higher quality, yield and reliability.

1 dwg, 1 ex

Description

The invention relates to the field of pipe production, namely the manufacture of especially thin-walled pipes by the method of cold periodic rolling.

Known methods of cold periodic rolling of pipes (Koff Z.A. et al. Cold rolling of pipes. Metallurgizdat. 1962, p. 7-9), in which the workpiece is deformed by work rolls or rollers running around the workpiece during its reciprocating motion. In the extreme rear position of the working stand, the rolls or rollers come out of contact with the rolled pipe and at this moment the feed cartridge feeds the pipe into the deformation zone and rotates it.

When the cartridge reaches the feed forward position (in front of the working stand), it releases the pipe and moves to its original rear position, where it captures the end of the next billet pipe and feeds it to the working stand. Moreover, for rolling the tail of the under-rolled part of the previous pipe, it is fed into the deformation zone by focusing on its rear end face of the front end of the subsequent pipe billet. A disadvantage of the known methods is that when rolling especially thin-walled pipes from respectively thin-walled billets, the supply force is sufficient to cut the ends of the pipes into each other, which makes it impossible to continue the rolling process and, therefore, stops the mill, cuts and removes the unfinished part of the finished pipe.

Rolling with a shortage of each pipe increases the expenditure coefficient of the metal of expensive especially thin-walled pipes and reduces the productivity of the mills due to the additional time spent on removing the unfinished pipe from the mill and installing a new billet pipe.

Of the known methods, the closest in technical essence is the method of cold periodic rolling of thin-walled pipes (V. A. Verderevsky. Roller mills for cold pipe rolling, M .: Metallurgy, 1992, p. 192-193), in which the rolling of the tail section is carried out by capturing the rolled part of the pipe with an exhaust cartridge located on the outlet side of the mill. In this case, the exhaust cartridge provides free extension of the pipe in the process of metal deformation and, when rolling the tail part, feeds the pipe by a predetermined feed amount, and the pipe, clamped by the cams of the cartridge, lengthening during the forward stroke of the stand, moves the exhaust cartridge in the rolling direction. The exhaust cartridge moves on the rollers along the guides, while the rail mounted on the cartridge rotates the gear and the sleeve of the overrunning clutch, the outer cage of which is connected by a gear transmission to the shaft of the feed mechanism, remains stationary. At the time of supply from the feed and rotation mechanism, through the shaft and gears, a rotation of the cage is communicated, which, rotating the sleeve, moves the rail with the exhaust cartridge to a predetermined feed amount.

Thus, during rolling, the ends of the billet pipe and the under-rolled pipe do not touch each other.

However, the movement of a heavy exhaust cartridge by this pipe and the rotation of the gears and bushings of the freewheel causes dynamic forces acting on the finished pipe, which, when rolling especially thin-walled pipes, leads to their damage. In addition, the presence of a number of dynamically loaded elements of the drive of the exhaust cartridge reduces the reliability of the mill.

The technical result of the invention is to improve the quality of rolled pipes, increase yield and increase the reliability of the mill.

The technical result is achieved by the fact that in the method of cold periodic rolling of especially thin-walled pipes, including clamping the billet pipe by the tail of the feed and rotation cartridge with subsequent feeding of the billet pipe into the deformation zone, rolling the billet pipe and moving the rolled pipe inside the exhaust cartridge until the cartridge reaches feeding and turning its extreme position, releasing the tail of the billet pipe and clamping the rolled pipe with an exhaust cartridge located on the output side of the mill, rolling the prefabricated part of the pipe, in which the pipe is pulled out by the amount of feed with an exhaust cartridge, moving it in the direction of rolling, while the exhaust cartridge is moved by means of a servo drive, the speed of movement of the exhaust cartridge is equal to the pipe elongation speed when rolling, the rolling pipe is fed in synchronously with feeding to the zone deformations of the next billet pipe, rotation of the rolling pipe is also carried out synchronously with the rotation of the next billet pipe.

At the end of the feed, during rolling of the pipe with the forward course of the stand, the pipe lengthens. In this case, the movement of the exhaust cartridge, necessary for the rolling of the tail of the finished pipe, is carried out from an individual servomotor together with the pipe at a speed equal to the elongation rate of the finished pipe.

The metal flow rate during pipe elongation is determined by the degree of pipe deformation and the speed of movement of the stand. The following simplified formula is known for determining the flow velocity of a metal:

$$V=V_{\mathrm{to}l}\frac{\Delta t_x}{t_x}$$

where V _CL - the speed of movement of the stand with rolls or of a separator with rollers;

- относительное обжатие стенок трубы в сечении «X» по длине зоны деформации металла. $$\frac{\Delta t_x}{t_x}$$

- relative compression of the pipe walls in section "X" along the length of the metal deformation zone.

The servomotor control program is based on the calibration of the working tool calculated for each rolling route and the specified speed of the working stand. Typically, the wall thickness in any section of the crimped pipe along the length of the deformation zone is determined by the dependence:

$$t_x=\frac{t_s}{\frac{(t_s/t_T)-\mathrm{one}}{\mathrm{one}-e^{-n_2}}\left(\mathrm{one}-e^{-n_{\mathrm{one}}\frac{x}{e_0}}\right)+\mathrm{one}}$$

where t _s - wall thickness of the workpiece;

- текущая координата сечения X по длине зоны деформации; $$\frac{x}{e_0}$$

- the current coordinate of the cross section X along the length of the deformation zone;

n ₁ and n ₂ are the steepness coefficients of the ridge profile.

This formula satisfies the falling mode of relative deformation according to the logarithmic dependence (see V.A. Verderevsky / Roller mills for cold pipe rolling, M .: Metallurgy, 1992, p. 137). Knowing the screw pitch S and speed V specified by the program, the number of revolutions of the servomotor required to move the exhaust cartridge at a speed equal to the pipe extension speed will be equal to:

$$n_{\mathrm{from}}=\frac{V}{S}$$

An example implementation of the proposed method is illustrated in the drawing.

The workpiece pipe 1 by the feed and turn cartridge 2, driven by the feed and turn mechanism by translational movement, is fed to the working stand 3 in the pipe deformation zone. The pipe is rolled with the passage of the finished pipe through the exhaust cartridge. When the cartridge reaches the feed and turn 2 to its extreme forward position, its cams release the undershot tail portion of the pipe 4, and the cartridge 2 moves back to its original position, where the cams clamp the rear end of the next billet pipe and begin to feed it to the working stand. At the same time, for rolling the tail of the finished pipe, the exhaust cartridge 5, driven by an individual servomotor 6 through the screw 7 and nut 8, pulls the under-rolled pipe by the feed amount synchronously with the feed of cartridge 2, thereby preventing the ends from joining. The rotation of the pipe is carried out from the servomotor 9 by means of the rotation shaft 10 and gear 11 synchronously with the rotation of the billet pipe by the cartridge 2.

The specified mode of operation of the exhaust cartridge when rolling is as follows. The operator sets in the ACS the required operation parameters of the exhaust cartridge: feed and rotation values, as well as the calibration of the working tool calculated by the formula for a specific stand speed (the speed of the exhaust cartridge as a function of the stand position). The linear position of the stand and its current speed are determined by the absolute position sensor. During rolling, on command from the ACS, the exhaust cartridge feeds and rotates by the specified values. For this, a position-locked structure for controlling the coordinates of servos is used. Upon completion of the testing of the specified movements, the servo feed of the exhaust cartridge is forcibly transferred to a speed-locked coordinate control mode. In the subsequent direct course of the stand, using the calibration entered by the operator and the current stand speed, the ACS calculates and issues the speed reference to the servo feed of the exhaust cartridge. Thus, in one double stroke of the stand, the servo drive for supplying the exhaust cartridge performs a given pipe feed in positional mode and its support in high-speed. This ensures the equality of the speeds of the exhaust cartridge and the finished pipe, elongated during rolling during the direct course of the stand.

When the mill is operating with the simultaneous use of the feed and rotation cartridge and the ACS exhaust cartridge, it additionally provides synchronous feed of the billet pipe with the feed and rotation cartridge and the finished pipe with the exhaust cartridge, which eliminates the cutting of pipe ends into each other. In this case, the rotation of the pipe by the exhaust cartridge is carried out synchronously with the rotation of the pipe-workpiece by the feed and rotation cartridge.

This method allows to obtain high-quality especially thin-walled pipes with a minimum metal consumption and increases the reliability of the mill.

Claims (1)

A method for cold periodic rolling of especially thin-walled pipes, including clamping a workpiece pipe by the tail of a feed and rotation cartridge, followed by feeding a workpiece pipe into a deformation zone, rolling a workpiece pipe and moving a rolled pipe inside the exhaust cartridge until the cartridge reaches and reaches its extreme position, releasing the tail of the billet pipe and clamping the rolled pipe with an exhaust cartridge located on the outlet side of the mill, rolling the tail of the tube billet, during which the pipe is pulled by the feed amount by an exhaust cartridge, which is moved in the rolling direction, characterized in that the exhaust cartridge is moved by means of a servo drive at a speed equal to the pipe elongation speed when rolling, while the rolling pipe is fed in synchronously with the next billet pipe being fed into the deformation zone, and the rotation of the rolling pipe is synchronized with the rotation of the next pipe-workpiece.

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