Method for controlling revolution number of rolls in order to minimize tube inner multiarc profile formation at passing tube

FIELD: automation of rolled stock production.

SUBSTANCE: at controlling thickness of tube wall in multi-stand continuous stretch-reducing mill, thickness of tube wall is measured behind mill by means of wall thickness measuring devices. Measured values are processed in computing unit. Revolution numbers of drive engines of rolls are controlled by means of units for controlling revolution number. In order to minimize formation of inner multi-arc profile at passing tube, total elongation value is kept constant due to changing revolution number of drive engines of rolls under control of computing unit.

EFFECT: enhanced quality of products.

5 cl, 4 dwg

 

The invention relates to a method for controlling wall thickness of the pipe in mnogoletija reducing stretch-reducing mill with devices for measuring the wall thickness of the pipe after the pressure reducing stretch-reducing mill computing device for processing measurement results and a device for controlling the speed of drive motors rolls.

In the manufacture of seamless and welded steel tubes often use the so-called reduction to tension, to a very flexible way to produce multiple pieces with specified size of many of the finished tubes with different diameter and wall thickness. The advantage of this method, which dispenses with the use of an internal tool that is quick and cost-effective change in wall thickness and diameter.

The closest technical solution according to the essential features and the achieved result is a method for controlling wall thickness of the pipe in mnogoletija continuous pressure reducing stretch-reducing mill, which includes a measurement of the wall thickness of the pipe after the pressure reducing stretch-reducing mill by means of devices for measuring the pipe wall thickness, processing of measured values via the computing device, and the speed control of drive motors rolls through the your device to regulate the speed of rotation (see DE 3819571 A1, 21 In 37/00, 07.12.1989).

Deformation of the pipe is reduced, with the stretching is carried out in the lot adjacent stands, however due to a change in speed in separate cages creates interaction between the crates and thereby purposefully regulated wall thickness of the finished pipe. The deformation of the pipe in reducing stretch-reducing mill is at present, as a rule, three-roll mills. For rolled products with reduction of the diameter of the pipe was not included in the gap between the rollers, which have traces of the reciprocating movement, the caliber of the rolls do not round, and three-roll cage - triangular-oval. This tripartite crate used the number of stands is usually round caliber. This is possible due to the fact that changing the diameter of the cage is small. This is necessary because the finished laminated pipe should be as round.

"Out-of-roundness" of the caliber necessary to optimally set depending on the reduction of diameter, wall thickness, etc. If the circle is too small, it leads to the appearance of marks and damage to the outer surface of the pipe. If the circle is too large, this leads to a pronounced non-uniformity of the thickness of the wall is key in cross section reduction-stretched tube. These uneven wall thickness have a hexagonal shape (three-roll stand) and are referred to as internal mnogogolovym profile. As all deviations of the wall thickness, the formation of inner mnogoluchevogo profile also means lower quality. Since the formation of inner mnogoluchevogo profile depends among other things on wall thickness or, more precisely, on the ratio of the wall thickness and pipe diameter, to achieve a large range of wall thickness required, as a rule, different calibration rolls, i.e. different ovality calibration rolls. Since the content of spare cages leads to a significant expenditure, it is usually used only two different calibration, namely one round with a small oval hole caliber for thick-walled pipes, and one oval with a large oval hole gauge for thin-walled pipes. Otherwise, try to reduce the formation of inner hexagon due to the optimal selection of secondary tensile stresses or strains" rolling of the product during its deformation.

If you choose a certain amount of education internal mnogoluchevogo profile, during the tests establish that the value mnogoluchevogo profile varies linearly depending on the strain. To change tensile change casinolink billets. Because of the steepness and position of the curve depends on many parameters (ratio of wall thickness to pipe diameter, shape, caliber, diameter rolls, temperature, material and so on), the high cost of testing to optimize stretching to perform a full range of hire. Even after the large cost of this optimization is not always receive a tube of small internal mnogogolovym profile, because certainly there changes in the current settings. In this situation you can try to reduce the formation of internal mnogoluchevogo profile by changing the wall thickness of tubular workpieces. However, this is not possible without loss of time and additional costs, depending on the method of rolling tubes of the earlier stages of deformation. In the end, many manufacturers, faced with a problem of quality deterioration due to the formation of internal mnogoluchevogo profile, have large costs to improve product quality or to put up with low quality products.

Along with the deviations of the wall thickness, resulting in the cross section of the pipe and remaining almost constant over the length of the pipe, there are deviations in wall thickness, which occur along the length of the pipe. Although there are methods and devices for regulating the speed of rotation the rollers, with the help of which you can compensate for these deviations of the wall thickness along the length of the rolling product, however, there is no way to control the speed of rotation to reduce the formation of internal mnogoluchevogo profile. For the above optimization stretching must be a concerted change in the wall thickness of steel billets. However, the wall thickness of tubular workpieces may not be part of the regulation control loop, since it is made in the running separately from reducing stretch-reducing rolling mill unit. According to the prior art, it is necessary to be reconciled with the formation of internal mnogoluchevogo profile due to the changing conditions of deformation and must be expended considerable effort to ensure optimization during preproduction.

The objective of the invention is to provide a method of minimizing the formation of internal mnogoluchevogo profile in combination with the extension of seamless pipe using the speed of rotation of the rolls.

The problem is solved in that in the method of regulating the thickness of the pipe wall in mnogoletija continuous pressure reducing stretch-reducing mill, including the measurement of the wall thickness of the pipe after the pressure reducing stretch-reducing mill by means of devices for measuring the pipe wall thickness, education is otcu measured values via the computing device, and the speed control of drive motors rolls through devices for regulating the speed of rotation, according to the invention, for minimizing the formation of internal mnogoluchevogo profile during passage of pipes General hood in reducing stretch-reducing mill support constant by changing the rotational speeds of drive motors rolls, managed computing device. This implementation of the method allows to minimize internal diversity.

The method according to the invention, solves described at the beginning of the problem of the prior art due to the fact that during the production process is reducing the formation of internal mnogoluchevogo profile using control loop and change the setting stretching. The stretching parameter determines the change of the number of speeds, and thus the distribution of strain in the rolling mill so that the total draft in the rolling mill remains unchanged. Because between the distribution parameter expansion and the formation of internal mnogoluchevogo profile there is a clear connection, it is possible to automatically reduce the formation of internal mnogoluchevogo profile without changing the wall thickness of steel billets.

The stretching parameter is defined so that when it is modified to increase the ratio of speeds of rotation in one group of rolling stands and simultaneously reduce in the other group rolling to the children, so the exhaust pipe as a whole remains constant. Using the fact that variables influencing the formation of inner mnogoluchevogo profile, inside of a number of stands of reducing stretch-reducing mill are usually very different. If you compare the input area reducing stretch-reducing mill with an output area, it can be stated that in the input area

- the ratio of wall thickness to pipe diameter less

- the ratio of pipe diameter to the diameter of the rolls more

- higher temperature,

- large oval caliber.

Added to this is the influence of design reducing stretch-reducing mill, as, for example, a given characteristic curves of the set speed.

Changing strain has a different impact on the formation of inner mnogoluchevogo profile depending on whether it comes in the input or output area reducing stretch-reducing mill. Thus specifies the dependence of the formation of internal mnogoluchevogo profile from the stretching parameter. Thus, a prerequisite for process control in order to reduce the formation of internal mnogoluchevogo profile.

Possible adjustment circuit is as follows. The value of internal mnogoluchevogo profile measured by the measuring devices, the thickness of the wall is CI pipes, emerging from reducing stretch-reducing mill, during the passage of pipes, for example, by measuring the wall thickness by ultrasound, to determine the dependence of mnogoluchevogo profile option changes the tension and set the tension so that the formation of inner mnogoluchevogo profile was minimal.

The constancy of the hood is provided, for example, due to the fact that the change in speed of the planning process determine for each size range of the car so that the average tension in reducing stretch-reducing mill remains constant. Day this can also be used during the manufacturing process of the adaptive computing method.

Below is a detailed description of the invention with reference to figures 1 to 4, where:

1 schematically depicts the formation of inner mnogoluchevogo pipe profile and the calculation of P mnogoluchevogo profile;

figure 2 - dependence of mnogoluchevogo profile from stretching;

figure 3 - possible changes in the distribution of strains;

figure 4 - dependence of mnogoluchevogo profile from the stretching parameter.

The method of regulating the thickness of the pipe wall in mnogoletija continuous pressure reducing stretch-reducing mill, according to the invention, includes a measurement of the wall thickness of the pipe after the pressure reducing and grow the aqueous mill through a device for measuring the wall thickness of the pipe, processing of measured values via the computing device, and the speed control of drive motors rolls through devices for regulating the speed of rotation. To reduce to a minimum the formation of internal mnogoluchevogo profile during passage of pipes General hood in reducing stretch-reducing mill support constant by changing the rotational speeds of drive motors rolls, managed computing device. Due to a change in rotational speeds of drive motors rolls increase the ratio of speeds of rotation in one group of rolling stands and simultaneously reduce in another group of rolling stands so that the total draft of the pipe remains constant. The measurement of internal mnogoluchevogo profile is realized by means of devices for measuring the wall thickness of the pipe after the pressure reducing exhaust mill, for example, by measuring the wall thickness by ultrasound, during the passage of the pipe. Then determine the dependence of mnogoluchevogo profile option changes the tension and set the tension so that the formation of inner mnogoluchevogo profile was minimal.

For the permanence of the hood changing the speed of rotation of rolls for each size range of rental Oprah is elaut so, to the average tension in reducing stretch-reducing mill remained constant. To change the rotation speeds of the rolls apply the adaptive method.

Figure 1 shows the formation of inner mnogoluchevogo profile and the calculation of P mnogoluchevogo profile. The thickness of the pipe in the bottom of the caliber roll designated as sathe wall thickness in the area of mid-side movement, as sb. Due to the symmetrical hexagonal form the inner contour of the pipe cross-sectional area of the pipe saand sbhave almost the same deformation in the corresponding six places. From the measured in these places values wall thickness determine the average value, as shown in figure 1. The value of R mnogoluchevogo profile is a positive value, if the place of lesser wall thickness is at the base of the caliber, and it is a negative value, if a smaller wall thickness is in the middle of the side of the gauge.

Figure 2 illustrates the dependence of mnogoluchevogo profile from stretching. Value mnogoluchevogo profile increases linearly with increasing strain. At lower values of strain it is negative, and at large values of the strain - positive. The value of strain at which the value mnogoluchevogo profile equal to zero, called what is "optimal stretching".

Figure 3 shows the potential change in the distribution of stretching, in which General hood in reducing stretch-reducing mill remains constant. On the curve ZP1stretching in the entrance area reducing stretch-reducing mill stretch and, thus, the hood rolled products more than in the output area. When the curve ZP2stretching and stretching distributed on stands about the same. On Z3stretching and stretching in the input train is less than the output stands.

Figure 4 shows the dependence of mnogoluchevogo profile from the parameter ZP stretching. In this example, the value mnogoluchevogo profile increases linearly with the increase of the stretching parameter. According ZP1, ZP2and Z3are specific state change of the tension, which is infinitely variable. Received during the rolling process according to the magnitude mnogoluchevogo profile from the stretching parameter determines the value of strain at which the value mnogoluchevogo profile equal to zero.

1. The method of regulating the thickness of the pipe wall in mnogoletija continuous pressure reducing stretch-reducing mill, including the measurement of the wall thickness of the pipe after the pressure reducing stretch-reducing mill by means of devices for measuring the pipe wall thickness, processing of measured values via the calc is slideling device and speed control of drive motors rolls through devices for regulating the speed of rotation, characterized in that to reduce to a minimum the formation of internal mnogoluchevogo profile during passage of pipes General hood in reducing stretch-reducing mill support constant by changing the rotational speeds of drive motors rolls, managed computing device.

2. The method according to claim 1, characterized in that by changing the rotational speeds of drive motors rolls increase the ratio of speeds of rotation in one group of rolling stands and simultaneously reduce in another group of rolling stands so that the total draft of the pipe remains constant.

3. The method according to claim 1 or 2, characterized in that the value of internal mnogoluchevogo profile is measured by a device for measuring the wall thickness of the pipe after the pressure reducing stretch-reducing mill, for example, by measuring the wall thickness by ultrasound during the passage of the pipe, determine the dependence of mnogoluchevogo profile from measurements of the stretching parameter and set the tension so that the formation of inner mnogoluchevogo profile was minimal.

4. The method according to any one of claims 1 to 3, characterized in that for the permanence of the hood changing the speed of rotation of rolls for each size range of rent determined so that the average tension in the reduction-restaino the mill remained constant.

5. The method according to any one of claims 1 to 4, characterized in that to change the rotation speeds of the rolls apply the adaptive method.



 

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FIELD: automation of rolled stock production.

SUBSTANCE: at controlling thickness of tube wall in multi-stand continuous stretch-reducing mill, thickness of tube wall is measured behind mill by means of wall thickness measuring devices. Measured values are processed in computing unit. Revolution numbers of drive engines of rolls are controlled by means of units for controlling revolution number. In order to minimize formation of inner multi-arc profile at passing tube, total elongation value is kept constant due to changing revolution number of drive engines of rolls under control of computing unit.

EFFECT: enhanced quality of products.

5 cl, 4 dwg

FIELD: manufacture of sheathing determined shape by cold reduction of hollow welded blank such as tube.

SUBSTANCE: method comprises steps of feeding and placing blank onto feed roller table; orienting and matching blank relative to rolling mill; deforming hollow welded blank between rolls of several successively arranged stands at simultaneously reducing blank along its perimeter and creating longitudinal tension drawing effort; finally working blank in multi-roll pass according to size of ready of product. Hollow welded blank is deformed while perimeter and thickness of its wall are hold constant during the whole manufacturing cycle beginning from guiding welded blank till discharge of ready product for several successive transitions. Strict order of said transitions is determined by creation of deformation zones at optimized stress-deformed state of metal and by deformation intensity between stands of rolling mill. Accuracy for keeping constant values of wall thickness and perimeter of initial welded tubular blank is controlled due to calibration of rolls in such a way that to act locally upon metal flowing in tube in critical points along perimeter. Reduction is realized due to preliminarily reducing tube along its contour for shaping ribs; further reducing blank for forming two basic surfaces of the most simple geometry and preliminarily forming two remaining basic complex-geometry surfaces. Then said two remained basic complex-geometry surfaces are finally reduced. Triangle bending portion is rolled and grooves are formed in vertical end strut and supporting platform. Triangle bending portion is additionally rolled and geometry parameters of shape that are important for operation are finally sized with possibility of compensation of errors of shape members with free dimensions. Then ready shape is straightened. Reduction is performed at similar angular velocity of rolls in all stands and slip is provided in zones of velocity error. Procedures of preliminary reduction of tube along its contour for forming ribs, further reduction of blank for forming two basic simple-geometry surfaces, preliminary forming of two remaining basic complex-geometry surfaces, further reduction for finally forming two complex-geometry basic surfaces, rolling triangle bending portion and forming grooves in vertical end strut and in supporting platform are performed in double-roll stands. Additional rolling of triangle bending portion, final calibration and straightening of ready shape are performed in multi-roll stands. Welded tubular blank is oriented in feed roller table in such a way that welded seam is in lower flange of shape that is parallel to supporting platform. The whole manufacturing process is realized in the same line. Invention provides possibility for acting upon stress-deformed state of metal in deformation zone for producing sheathing preset-contour shape from widely used in industry welded tube blank with diameter 114 mm and wall thickness 3 mm during optimized technological mode concerning metal state and deformation intensity.

EFFECT: enhanced accuracy of geometry size, lowered energy consumption for making shape.

5 cl, 5 dwg, 1 ex

FIELD: technological sizing tool for reduction tube rolling mill.

SUBSTANCE: sizing tool includes several successively arranged two-roll reducing shaping roll grooved passes and multi-roll passes for final sizing and straightening of ready product. Said shaping roll grooved passes are arranged according to strict order without angular shift of their parting planes. Profile of cross section of shaping rolls of each next pass is formed by recesses and protrusions with curvilinear and (or) rectilinear surfaces with possibility of proportional geometrical approach to shape of ready product. It is achieved due to satisfying condition of equal values of summed perimeter of grooved rolls of each stand and outer perimeter of initial blank. Profile of finish roll grooved passes is identical to outer contour of ready product and it is possible to adjust it in admissible range while using sixteen reduction shaping stands and four finish passes. According to invention it is possible to act upon stress- deformed state of metal in deformation zone for making preset-contour section of widely used in industry welded tube 114 x 3 mm in manufacturing mode optimal from view point of metal state, deformation intensity and comfortable condition of tool operation.

EFFECT: simplified design and manufacturing process of rolls, improved accuracy of products, lowered energy consumption.

2 cl, 5 dwg

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