UA65925A - Method for adjustment of value of forced rolling radius and cold-rolling pilger mill for tubes for its embodiment - Google Patents

Abstract

Method for adjustment of value of forced rolling radius of cold-rolling Pilger mill for tubes along the length of their motion by final twisting of the driving gears of rolls by displacement of racks. The racks are displaced in accordance with the function of change of difference of natural and forced rolling radii. The cold-rolling Pilger mill for tubes includes the drive of reciprocating displacement of racks in the form of a hydraulic cylinder of bilateral action connected with a plunger pump of proportioned portioned admission of working fluid through the valve device of change of liquid admission into the cavity of straight and reverse piston stroke, and the drive of plunger pump is used from the step electric motor with adjustable pulse frequency.

Description

The invention relates to pipe-rolling production, in particular to the mills of cold pilger rolling of pipes (CPT), which have on the rolls streams of a variable profile in length and intended for the production of seamless pipes.

It is known /1/ that the rolling radius of rolls with streams of a variable profile on the metal being rolled, during a free pilger process (pilger mills of hot rolling, etc., in which the rolls are in a stationary cage, and the metal has the opportunity to move freely along the axis of rolling) is a variable value determined by the depth of the stream and the shape of its transverse profile in each cross section along its length.

The states and process of cold mill rolling differ in that the rolls compress the metal, making a reciprocating-rotating movement, and the metal (workpiece) does not have the ability to move freely along the rolling axis.

The rotation of the rolls is carried out due to the interaction of their driving gears with toothed rails, and their rolling on the rolled metal occurs with sliding, if the radius of rolling on the rail does not coincide with the rolling radius of the free pilger process. The radius of the pitch circle of the driving gear roll, which determines its rotation, is called the forced rolling radius, and the rolling radius of the metal roll during the free rolling process is called the natural rolling radius.

The inconsistency of the specified radii causes additional uncompensated sliding of the stream on the metal, as a result of which there are axial forces acting on the workpiece, the working cone of the mandrel and the rolling pipe.

The magnitude of these forces is greater, the greater the discrepancy between the specified rolling radii in each instantaneous center of deformation.

Axial forces have a negative effect on both the rolling process and the operation of the state mechanisms, mainly the workpiece chuck, the device for attaching the reference rod and the rod itself.

Since the billets and the rolled pipes on the rolling line move into the joint, pushing each other, with excessive axial force, their ends are pressed in - docking. The magnitude of the axial forces limits the wall thickness of the rolled blanks and pipes.

A number of methods are known to bring the value of the forced rolling radius closer to the natural one due to structural changes in the drive of the rolls (3, 4, 5, 6, 7, 8 and 9).

So, for example, instead of cylindrical drive gears, it is suggested to use non-circular gear wheels with a variable radius of the dividing wheel /3/, or instead of drive gears to use drive pulleys of a variable radius /4/, or to move the racks by turning the gear to a certain angle with a crank-rod /5,6/ or cam /9/ mechanisms.

All these known devices and their corresponding methods have a common significant drawback, which consists in the fact that the value of the forced rolling radius can coincide with the value of the natural one only in one separate case along the entire length of the working part of the stream or its part only under the condition that the dimensions of the dividing circle of a non-circular gear, the profile of a non-circular drive pulley or cam corresponds to the actual change in the natural rolling radius.

Even if the above condition is fulfilled, a non-circular gear, cam or pulley will be suitable for rolling pipes along only one route (the diameter of the workpiece is the diameter of the pipe being rolled). In order to roll pipes along all the variety of routes, it will be necessary to keep a large fleet of rather time-consuming to manufacture replaceable non-circular gears, pulleys or cams.

It should be noted that it is difficult to determine the exact value of the natural rolling radius in advance, since its value is affected by such parameters that are difficult to determine, for example, the coefficient of friction, the shape and dimensions of the transverse profile of the stream, and during the operation of the tool - the amount of wear of the stream.

The closest in terms of technical essence to the method and device that are claimed is the device accepted as a prototype /9/, in which the working rolls interact with toothed racks moved from piston throttle hydraulic amplifiers with control spools, the rods of which are connected by rods with levers installed on the shaft, the end of which is connected to the kinematic cam through a rocker-lever system with an adjustable swing angle.

This provides regulation of the speed of movement of the rails without changing the cam and excludes their non-synchronous movement.

The disadvantage of this rolling condition is the presence of significant dynamic loads on the drive of the calibrated rolls and the mandrel assembly, which leads to rapid wear of parts and assemblies.

The basis of the invention is the task of increasing the durability of mechanisms in the cold rolling state.

This task is solved due to the technical result, which consists in reducing the axial forces that occur during rolling of the workpiece.

In order to achieve the above-mentioned result in the method of adjusting the forced rolling radius of the rolls of the cold relief rolling mill along their length by turning the drive gears of the rolls by moving the racks, according to the invention, the racks are moved according to the function of changing the difference between the natural and forced rolling radii:

Akeh - Ash -(Ав-(0.69-0.73)х|-Нш where: Akeh - natural rolling radius that corresponds to this stream;

Вв - the radius of the roll barrel;

Nx - the depth of the stream according to its calibration;

Ash is the radius of the dividing circle of the driving cylindrical gear roll, while the law of movement of the toothed rails along the length of the rolls is set by changing the frequency of feeding dosed portions of the working fluid into the cavity of the hydraulic cylinder, which sets the rack in motion, and the position of the dead points of the movement of the rolls and rails is coordinated due to the electronic connection between the drives of rolls and rails.

To achieve the above-mentioned result in the state of cold pilger rolling of pipes, which includes a bed with movable toothed rails placed on it, which are engaged with the driving gears of calibrated rolls, a drive for reciprocating movement of rails with control spools, according to the invention, a drive for reciprocating movement of rails is made in the form of a double-action hydraulic cylinder, connected to a plunger pump of metered portion supply of working fluid through a valve device for switching the supply of fluid into the cavity of the forward and reverse strokes of the piston, and the plunger pump is driven by a stepper electric motor with an adjustable pulse frequency.

The technical result of the application of the claimed method and device is that the adjustment of the forced rolling radius to the natural value eliminates the uncompensated sliding of the stream on the rolled metal, which causes axial forces.

Reducing or completely eliminating axial forces allows: to reduce the intensity of wear of the stream due to the elimination of additional sliding of the metal along the stream, as well as to expand the range of diameters of pipes and blanks rolled on the mill; reduce the allowable thickness of the wall of pipes and blanks, which was limited by the presence of axial forces, prevent the joining of pipes and blanks; increase the deformation per pass within the plastic capabilities of the metal by increasing the size of the blanks and reducing the size of the rolled pipes.

As a result of a comparative analysis of the proposed method of adjusting the value of the forced rolling radius of the rolls of the state of cold pile rolling of pipes with the prototype, it was established that they have the following general features: rotation of the driving gears of the rolls by moving the toothed rails; and distinguishing features: toothed rails are moved according to the function of changing the difference between natural and forced rolling radii

AkehX-Ash--|(Av-(0.69-0.73)х|-Ash the law of movement of toothed racks along the length of the rolls is set by changing the frequency of feeding dosed portions of the working fluid into the cavity of the hydraulic cylinder, which sets the rack in motion; the position of the dead the points of movement of the rolls and rails are coordinated due to electronic communication between the drives of the rolls and rails.

Thus, the proposed method of regulation has new operations and a new way of performing operations.

As a result of a comparative analysis of the proposed state of cold pile rolling of pipes with the prototype, it was established that they have the following general characteristics: bed; movable toothed rails placed on the bed; the rails are engaged with the driving gears of the calibrated rolls; drive of reciprocating movement of rails with control spools; and distinguishing features: the reciprocating drive is made in the form of a double-action hydraulic cylinder, connected to a plunger pump for metered portion supply of working fluid through a spool device for switching the fluid supply to the cavity of the forward and reverse strokes of the piston; the drive of the plunger pump is made from a stepping electric motor with an adjustable frequency of pulses.

Thus, the proposed state of pilger pipe rolling has new nodes and details, a new connection between nodes.

There is a cause and effect relationship between distinctive features and the technical result achieved.

Due to the adjustment of the forced rolling radius according to the specified dependence by moving the gear rack using different modes, axial forces in the rolling zone were reduced to a minimum, which reduced the wear of parts and machine assemblies, and this led to an increase in their durability.

Thanks to the equipment of the drive for reciprocating movement of the rails with a plunger pump with a dosed portion supply of the working fluid, and the implementation of the pump drive from a stepper electric motor with an adjustable frequency of pulses, it became possible to move the rail according to the law defined in the invention, which allows equalizing the forced and natural rolling radii, which reduces the axial effort and leads to an increase in the durability of nodes and parts of the state.

Excluding at least 6 of them from the above set of distinguishing features does not provide a solution to the task - increasing the durability of mechanisms in the cold rolling state.

The claimed technical solution is not known from the prior art and is therefore new.

The proposed technical solution has an inventive level, because the method of adjusting the forced rolling radius of the rolls and the state of cold relief rolling of the pipes, discussed above, are not obvious to a specialist from the state of the art.

The proposed technical solution is industrially suitable, because its technical and technological implementation does not cause difficulties. Based on this decision, a sketch design of the prototype was completed.

Thus, the proposed technical solution can be given legal protection because it is new, has an inventive level and is industrially applicable, meeting all the criteria of an invention.

The invention is explained by the drawing (Fig. 1), which shows the state diagram of cold pile rolling of pipes, which implements the proposed method of regulating the forced rolling radius of the rolls.

The device, the scheme of which is shown in the drawing, consists of a hydraulic cylinder 1, a movable toothed rack 2, a driving roller gear 3, a spool 4, a plunger pump 5, a tank 6 for holding the working fluid, a stepper motor 7, regulating flow valves 9 and 10, and as well as non-return valves 11 and 12.

At the same time, calculating the calibration of the stream for a given rolling route, determine the profile of the stream along the length of its working part and the diameters, for example, according to the function

Oh - Ot (Oz -Ot - Utip che Tut X where: Ot is the diameter of the rolling pipe;

Oz - diameter of the workpiece;

Ttip - the conicity of the stream in the crimp (at the border of the crimping and calibrating areas);

X - current coordinate along the length of the stream;

And - the length of the crimping zone of the stream; n is an indicator of the degree that determines the steepness of the creek crest.

As you know, the depth of the stream for a given value of X is

Nx-(Ox-Kku/g2, where K is the nominal gap between the rolls.

Next, the function of changing the natural rolling radius is found, as Akeh-B-(0.69...0.73)Nx and the function of changing the difference Akeh--Ash.

Knowing the volume of the dosed portion of the working fluid, issued in one double stroke of the plunger, and the volume of the cavities of the forward and reverse strokes of the hydraulic cylinder of the gear rack drive, calculate the required volume of the working fluid fed into the corresponding cavity of the cylinder to move the piston by the required amount.

Knowing the function of changing the speed of the translational movement of the rolls (cassettes or cages), calculate the function of supplying the number of portions of the working fluid to the cylinder, determined by the frequency of the pulses of the stepper motor. This function is entered in the form of a control program in the corresponding stepper motor device.

The device works like this.

In the bed of the cage, a cassette with rolls on which a stream of variable profile is made moves along the guides: at the maximum radius of the stream, the rolls form the non-working gauge, and at the minimum radius - the outer diameter of the finished pipe. As the rolls rotate, the gauge sizes gradually decrease and the rolls compress the workpiece on the mandrel, which increases as the radius of the stream decreases. After turning the rolls by 360", the non-working gauge is opened again and the feeding device again sets the workpiece in the rolls. At the same time, the workpiece is turned by 90.

When the rolls move forward, the amount of working fluid necessary for the movement of the rails enters the hydraulic cylinder, determined by the frequency of delivery of dosed portions from the plunger pump.

The amount of working fluid entering the cylinder is variable depending on the length of the rolls and the speed of their translational movement, it pushes the piston and moves the rails according to the required law.

The rails rotate or retract the driving gears, increasing or decreasing their instantaneous rolling radius on the rail to the value of the instantaneous natural rolling radius of the rolls. Rolling of the roll on the metal and on the toothed rail becomes the same, thereby preventing uncompensated sliding of the metal along the stream and the appearance of axial forces caused by this sliding.

With a small amount of the dosed portion of the working fluid issued by the plunger pump, and a large range of pulse frequencies of the stepper motor, the process of turning the gears will occur almost non-stop (without jolts).

Thus, the proposed method and device make it possible to quickly adjust the control program depending on changes in rolling conditions, for example, wear of the stream, poor technological lubrication, new material (copper, aluminum, titanium alloy, etc.) and other factors that affect the coefficient friction. Such correction is possible, for example, according to the magnitude of the resulting axial forces, measured experimentally, which allows continuous pipe rolling in the optimal mode, which ensures minimal wear of the mechanisms.

Sources of information: 1. P.T. Emelianenko. The theory of oblique and pilgrim rolling. M., Metallurgizdat, 1964. 2. Yu.F. Shevakin. Calibration and stresses in cold rolling of pipes M., Metallurgizdat, 1963. 3. Oki Masami, Kadokawa Masohiro, Kokata Munzkatsu: Sumitomo kinzo-ku koge. Application 61-108410 Japan.

Application 30.10.84. Me59-229567, publ. 05/27/86. MKY At 21 At 21/00. 4. V. I. Sokolovsky, A. A. Fotov, V. A. Verderevsky. The working frame of the cold rolling mill for pipes. A.S. USSR

Me876219 dated 16.08.79. Publ. Bul. Me401981. 5. O.A. Semenov, V.F. Frolov, L.V. Tymoshenko, V.Ya. Zamoshchikov, A.P. Horyun. V.A. Zazymko. A.S. USSR Me376136, cl. B21 35/10, B218 21/00. From 04/05/1973, Bul. Me17. 6. E.S. Bondarenko, V.A. Myronenko, I.N. Potapov, I.A. Grekhov. Condition of cold rolling of pipes. A.S. USSR

Me403242, cl. B21 B21/00. 7. P.M. Orro, A.V. Kyrilenko. Roll drive of the cold pipe rolling mill. A.S. USSR Mo219528, cl. 7a. 16/01

IPC 821 V, 1966. 8. T.A. Saksagansky, P.I. Orro, B.A. Iskra, V.S. Matveev, A.V. Kyrylenko, B.N. Varenyk. The drive of the working rolls of the cold pipe rolling mill. A.S. USSR Mo293407, class B21 B35/10, 821 B821/00. 9 V.A. Verderevsky,

A.A. Morozov. The working frame of the roll mill for cold rolling of pipes. A.S. USSR Mo275034, cl. B21817/00, application 06.05.67, publ. 22.08.1973, Bull. Me3z4. N

SU, Ya

Aeneas with Ya t par d, (from - d- E vok, I

GI TD A. She is from 8; (M)

Fig. 1

Claims (3)

1. The method of adjusting the value of the forced rolling radius of the rolls of the cold mill rolling of pipes along the length of their course by tightening the drive gears of the rolls by moving the toothed rails, which is distinguished by the fact that the toothed rails are moved according to the function of changing the difference in natural and forced melting radii: eV (0.69 - 0.73)- пХ|- Vsh where: Akyeh - natural rolling radius that corresponds to this stream; Вв - the radius of the roll barrel; Nx - the depth of the stream according to its calibration; Ash is the radius of the pitch circle of the driving cylindrical gear roll. 2. The method according to claim 1, which differs in that the law of movement of the toothed rails along the length of the rolls is set by changing the frequency of feeding dosed portions of the working fluid into the cavity of the hydraulic cylinder, which sets the rails in motion, and the position of the dead points of the movement of the rolls and rails is coordinated due to the electronic connection between the drives of rolls and rails. 3. The state of cold pilger rolling of pipes, which includes a bed with movable toothed rails placed on it, which are engaged with the driving gears of calibrated rolls, a drive for reciprocating the movement of the rails with control spools, which is distinguished by the fact that the drive for reciprocating the movement of the rails is made in in the form of a double-action hydraulic cylinder, connected to a plunger pump of metered portion supply of working fluid through a valve device for switching the supply of fluid into the cavity of the forward and reverse strokes of the piston, and the plunger pump is driven by a stepper electric motor with an adjustable pulse frequency.