EA042503B1 - METHOD AND DEVICE FOR DETERMINING TWIST ANGLE DURING ROLLING OPERATION - Google Patents

Description

The invention relates to the field of manufacturing seamless pipes by transverse piercing or elongation and relates to a method for non-destructive testing in the production process of hot-rolled pipes, in particular hollow pipes made of steel, commonly referred to as sleeves. The invention also relates to a device for carrying out this method.

In the production of seamless pipes by transverse piercing, a cylindrical steel blank or billet is introduced as an input product from the input side of the rolling device and between rolls having a predetermined inclination with respect to the axis of the billet. The rolls subject the workpiece to stress in excess of the yield strength of the workpiece material. The rolls pull the billet towards a mandrel which pushes material outward from the center of the billet and pulls the billet material outward and towards the back of the rolls, thus producing an output product called a sleeve with an inner diameter and an outer diameter, respectively. In transverse piercing, the workpiece and the sleeve formed from the workpiece form a workpiece. The sleeve exits the rolling device on the output side of the rolling device.

In the process of elongation by transverse rolling, the sleeve as input product is introduced at the input side of the rolling device in the same way as the workpiece, and is pushed out from the output side of the specified rolling device. You can use an internal tool such as a mandrel or a long mandrel. The corresponding output product is called a thin-walled sleeve.

When piercing or lengthening the rolls, the workpiece is rotated. At the end of the firmware operation, the workpiece becomes a sleeve. At the end of the elongation operation, the sleeve becomes a thin-walled sleeve. The important elements of the cross rolling mill are the rolls and the mandrel or long mandrel. All rolls rotate in the same direction and act like a gear wheel along with the rolled material, which is located in the center. Thus, the material is rotated in the direction opposite to the direction of rotation of the rolls. The inclined position of the roll results in a helical movement.

The rolls can either be barrel shaped, i.e. the axes of the rolls are located in planes that are parallel to the axis of the rolled material or they have the shape of a cone. When using a cone, the axes of the rolls intersect the axis of the workpiece at one point if the feed angle is zero.

Such a rolling device is described in US Pat. No. 3,719,066.

The piercing process or elongation process entails twisting of the output product as a result of the different surface speeds of the rolls along the axis of the material. Twisting depends on many factors, including expansion coefficient, type of piercing mill, feed angle, rolling angle, roll geometry, material grade, feed efficiency. Thus, twisting depends on the rolling device, materials and parameters of the rolling process.

In addition, the rolling process may cause defects in the hollow tube or thin-walled sleeve being produced. Therefore, finished hollow tubes or thin-walled sleeves are subjected to inspection to detect these defects. External surface defects can be transverse, longitudinal or oblique. Oblique defects have an orientation with an angle between the transverse and longitudinal orientations. Defects can be located on the outer surface of the sleeve or thin-walled sleeve. Oblique outer surface defects are usually associated with twist orientation and can be easily detected by ultrasonic testing if the twist angle is known. Therefore, there is an advantage in determining the angle of twist of a hollow pipe or thin-walled sleeve in order to subsequently evaluate the orientation of oblique defects in the outer surface, and therefore to improve the detection of these oblique defects using non-destructive testing, such as ultrasonic testing.

One known method for evaluating the angle of twist is to make a notch on the outer surface of a representative workpiece extending along the entire workpiece, and thereby obtain a grooved workpiece having a longitudinal groove. Then the workpiece with a groove is stitched. The twist angle can be estimated after piercing by measuring the imprint of this groove on the sleeve. This solution is impractical and costly as it requires multiple tests and at least one test for each set of parameters. Such a decision takes a lot of time and resources.

Thus, there is a need for a non-destructive method and apparatus that results in the determination of the twist angle in an efficient manner and that is compatible with industrial rates.

Advantageously, the method and apparatus according to the invention are compatible with all different cross-rolling processes, where elongation processes such as Mannesmann rolling, pilgrim rolling, mandrel rolling, continuous long mandrel rolling are carried out after piercing.

Advantageously, this method according to the invention is a non-destructive method. In addition, the twist can be determined independently of all the parameters of the cross rolling stand and the piercing process.

The present invention relates to a non-destructive method for determining the twist angle of an output product during rolling of an input product into said output product, comprising the following steps:

measuring the input rotation speed of the input product during said rolling;

measuring the output rotation speed of the respective output product during said rolling;

measuring the longitudinal output velocity and/or longitudinal input velocity of said respective output product and/or input product;

determining a rotation delta based on said input rotation speed and said output rotation speed;

determining a twist angle based on said spin delta and said longitudinal exit speed and/or longitudinal input speed.

In one aspect, input rotational speed, output rotational velocity, longitudinal output velocity, and/or longitudinal input velocity may be measured from a start time (t ₀ ) to an end time (t1).

According to another aspect, input rotational speed measurements can be made from the intake start time to the intake end time, and output rotation speed measurements are made from the exhaust start time and exhaust end time, while the indicated intake start time and intake end time determine the time window at the entrance , the specified release start time and release end time define an output time window, and an input time window and an output time window have a common time window having a start time (t0) and an end time (t1).

The method may further include the step of measuring the exit outer diameter of the exit product.

The angle of twist (TA) can be determined from formula (F)

TA = atan^T^)

E ^ν »τ (F) ' where Delta is the difference in the number of revolutions between the number of revolutions of the output product and the number of revolutions of the input product in the time window from the start time t ₀ to the end time t ₁ or in the general time window;

ODH is the outer diameter of the output product;

VHT is the longitudinal exit velocity of the output product.

In an embodiment, the longitudinal exit velocity VHT is changed to the longitudinal entry velocity VBT multiplied by the elongation factor ke.

The method may further include the step of measuring the inlet outer diameter of the inlet product.

In one aspect, exit velocity measurements and exit outer diameter measurements may be made in the same plane orthogonal to the axis of the exit product.

According to another aspect, the inlet velocity measurements and the inlet outer diameter measurements may be made in the same plane orthogonal to the axis of the inlet product.

The start time (t ₀ ) and end time (t1) can be selected in the steady state phase to more accurately determine the twist angle.

In one embodiment, the rolling operation may be a piercing operation in which the input product is a billet and the output product is a sleeve.

In another embodiment, the rolling operation may be an elongation operation in which the input product is a sleeve and the output product is a thin walled sleeve.

The present invention is also a device for non-destructive determination of the angle of twist during rolling of the input product into the output product, comprising:

the first input sensor configured to measure the speed of the input product;

the first output sensor, configured to measure the speed of the output product;

sensor (60) outlet outer diameter;

an electronic device configured to determine the twist angle of said output product based on measurements taken by said sensors during rolling.

The first outlet sensor (58) may be configured to measure the lateral outlet velocity of the outlet product, and the apparatus may further comprise a second outlet sensor (57) configured to measure the longitudinal outlet velocity of the outlet product.

The first inlet sensor (53) may be configured to measure the transverse inlet velocity of the inlet product.

According to one embodiment, the device may include a second inlet sensor (52) configured to measure the longitudinal inlet velocity of the inlet product.

The device may additionally contain a sensor (54) input outer diameter.

- 2 042503

In one embodiment, the first input sensor (53), the second input sensor (52), and the input outside diameter sensor (54) may be positioned such that measurements are made in the same input measurement plane (55).

In one embodiment, the first outlet sensor (58), the second outlet sensor (57), and the outer diameter outlet sensor (60) may be positioned such that measurements are made in the same outlet measurement plane (59).

List of figures

In FIG. 1 schematically shows the roll gap of a cross rolling stand.

In FIG. 2 is a schematic expanded view of the curl imprint output.

In FIG. 3a and 3b schematically show the grooved blank and the resulting grooved sleeve after piercing.

In FIG. 4 shows a diagram of the measurements of the rolling force during the piercing of the workpiece.

In FIG. 5 shows a schematic view of the device according to the present invention.

Detailed description

The general principle of the pipe rolling process is shown in Fig. 1. Below the principle is described in relation to firmware, but the extension process follows the same basic steps. The process starts with a round bar, commonly referred to as a billet (1), which is heated to rolling temperature and then introduced into the rolling machine through the inlet side (5) between two inclined, contoured rolls (2a, 2b) driven in the same direction of rotation. The blank (1) is pierced by the inner mandrel (3). Thus, the workpiece (1) is rolled in one direction along the inner mandrel (3) and between the contoured rolls (2a, 2b) to form a roll gap. The blank (1) is converted on the other side of the inner mandrel (3) into a sleeve (4). The sleeve exits the rolling device from the output side (6). The device may be configured to increase or maintain, or slightly reduce the outer diameter of the sleeve compared to the outer diameter of the workpiece. The device can be configured to produce a sleeve with a given wall thickness.

Tests were carried out to determine how the workpiece (1) deforms during piercing. Tests were carried out with workpieces which were grooved to form a mesh with an edge length of 60 by 60 mm. The mesh grooves were 3 mm deep and 4 mm wide. 20 blanks were produced and processed under various rolling conditions.

In FIG. 2 is a schematic expanded view of the sleeve (4). The specified sleeve (4) contains the first end part (21) or the head part, the central part or part (23) with a grid, the second end part (22) or the tail part. The twist line (24) is shown. It is possible to define three regions representing different twist line patterns (24). The twist line (24) forms a substantially regular ellipse along the mesh portion (23). This twist line (24) has a more irregular shape at the head (21) and at the tail (22). Thus, the twist line (24) in the mesh part (23) corresponds to a substantially constant angle of twist along the mesh part (23), while the twist at the ends is affected by the filling and emptying of the roll gap. In fact, these three areas correspond to three phases of the piercing process: the head end of the sleeve is manufactured during the gripping or rolling start, the mesh part (23) is manufactured during the steady or steady state phase, the tail (22) is manufactured during the final or completion phase rolling.

3a, the characteristics of the steel were observed throughout the test. In FIG. 3a shows schematically in expanded view a special grooved entry product: a blank (30) with straight axial grooves (31) and straight circular grooves (32). Before rolling, the grooved billet (30) has straight axial grooves (31) oriented in the longitudinal direction and circumferential grooves (32) oriented in the transverse direction, forming a grid pattern. Several blanks of different sizes were made according to this pattern. The blanks were heated and rolled according to several different parameters such as expansion coefficient and different wall thicknesses of the sleeve. After piercing the grooved blanks (30) on the respective grooved sleeves (33), it was found that the circumferential grooves (32) remain transversely oriented and more distant from each other, while the axial grooves (31) have an angle relative to the longitudinal direction and form spirals. , as shown schematically in FIG. 3b. Thus, the process of rotation of the rolls (2a, 2b) deforms the metal in a spiral.

It was found that the deformed pattern was regular along the grooved sleeve (33) except for the beginning and end of said grooved sleeve (33), and the spirals had approximately the same angle, while the specified angle was essentially constant, except for the end parts of the pipes, where deformations are less significant, with the helix angle being smaller than the helix angle observed over most of the pipe body.

Based on these tests, several mathematical models were tested. An approach was found in which the angle of twist is a function of the component of the relative displacement of the point of the hollow pipe from the first moment of time to the second moment of time, as well as a function of the amount of relative rotation of the hollow pipe with respect to the rotation of the workpiece during the specified displacement from the specified first moment. time until the specified second point in time.

In addition, estimation of workpiece or sleeve displacement can be performed by integrating the pipe velocity at a particular time coordinate.

With the method of the present invention, it is possible to determine the actual twist at the head and tail, but less accurate since the twist along said head and tail is changed. Moreover, it is of no real interest for the purpose of subsequent non-destructive testing, since the change in angle is currently not taken into account in existing testing machines. Thus, such twisting at the head and tail is considered to be indeterminate twisting for the purpose of non-destructive testing.

Determining the length with an indefinite twist is of interest, either the length with the twist of the head or the length with the twist of the tail. The length with indefinite twist can be determined by the following steps:

measuring the rolling force at the time of rolling the billet, or measuring the roll torque at the time of rolling the billet;

measurement of the transverse speed of the sleeve;

determining a first time window between a first time point when the rolling force or roll torque increases from zero and a second time point when the rolling force or roll torque reaches a predetermined force value or a predetermined torque value, respectively;

determining the grip length (21) based on the measurement of the lateral velocity and the first time window;

determining a second time window between a third time point when the rolling force or roll torque is reduced from the force set value or the set torque value and a fourth time point when the rolling force or roll torque reaches substantially zero;

determining the length of the free part (22) based on the measurement of the transverse velocity and the second time window.

In this way, lengths with an indeterminate angle of twist in the tail section and head section are determined.

The head twist length or the tail twist length can be independently determined.

The steady state phase can be defined as the rolling force or roll torque, defined as 92% of the maximum rolling force applied during piercing.

In FIG. 4 shows a curve representing a typical function of roll torque versus time, with grip (41) with increasing torque up to a substantially flat portion of the curve corresponding to the steady state phase (42), which may include some unevenness while maintaining the torque at above 92% of the maximum applicable torque, and ending at the free end, which corresponds to a reduction in the roll torque value.

The established model basically works for the steady state phase. The steady state phase corresponds to the running time when the rolling speed or torque/force is substantially constant, or otherwise defined, excluding the initial speed increase at the beginning of rolling and the final speed decrease at the end of rolling from the running time. The steady state phase can also be referred to as a steady state process. As can be seen in FIG. 4, when the pipe is subjected to rolling, at the beginning of rolling (41) there is a gradual increase in rolling forces applied to the billet and an increase in speed, and at the end of rolling (43) there is a decrease in rolling forces and speed. This is due at least to the entry and exit of the billet and pipe into and out of the rolls. Finally, the model is more suited to the steady state phase (42) where the rolling forces are substantially constant, while the rolling speed is also substantially constant, ie, less than 10% change over time.

The steady state phase can be determined based on the rolling force and roll torque readings.

According to one aspect of the present invention, the angle of twist (TA) is determined by the formula (F)

Delta xODfjXn (F) where Delta is the difference in number of revolutions between the number of revolutions made in the output product, i.e. the sleeve or thin-walled sleeve, and the number of revolutions made in the input product, i.e. the billet or sleeve, in the time window from the start time t ₀ to

- 4 042503 end time t1,

Delta revs _vshusk revs _vpu s _K

When applied to the firmware operation, the formula takes the form: Delta _sleeve revolutions - _billet revolutions

The _{spin speed} can be determined by dividing the integral of the transverse output velocity between the start time t ₀ and the end time t1, measured on the outer surface of said output product, by the outer diameter of the output product, which is a sleeve or a thin-walled sleeve.

The _inlet revolutions can be determined by dividing the integral of the transverse inlet velocity between the start time t ₀ and the end time t1, measured on the outer surface of the specified inlet product, by the outer diameter of the inlet product, which is a blank or a sleeve.

Velocity measurements are surface speed measurements. These measurements can be performed using optical means. These measurements can be made using laser speed sensors. The advantage of such a sensor is that velocity measurements can be made with hot material. In fact, the billet and the liner, the thin-walled liner, can have temperatures of several hundred degrees during rolling. Tests have been carried out with hot and cold materials and it has been found that such laser sensors are insensitive to material temperature differences.

Alternatively, it may also be possible to directly estimate the output or input rotational speeds by means of a sensor measuring the rotational speed directly (in rad/s) instead of the linear transverse velocity (in units of length divided by a unit of time, such as a second) without the need to measure the outside diameter.

ODH is the outer diameter of the hollow pipe.

The outer diameters of the workpiece and the sleeve can be measured with optical sensors.

The start time t0 and the end time t1 may correspond to the selected time window. Preferably, the start time t ₀ and the end time t ₁ are chosen to be within the steady state phase of the piercing of the workpiece.

VHT is the longitudinal exit velocity of the output product. With regard to the measurement of rotational speed, this measurement is performed by means of an optical means such as a laser sensor.

Alternatively, the longitudinal inlet velocity of the inlet product can be used with a multiplication factor k _e corresponding to the elongation factor.

In one embodiment, the first start time and the first end time may be selected for measurements performed on the input product, and the second start time and the second end time may be selected for measurements performed on the output product; with the corresponding definition of the first time window or the second time window. In this case, the formula is applied to a common time window common to the first time window and the second time window. Alternatively, time windows of the same length are selected in the first time window and the second time window and are selected in the steady state phase to apply formula (F).

The present invention also relates to a device for measuring the angle of twist of the sleeve, which contains:

1. Input module (51).

Input module (51) contains:

Device (53) for measuring the input transverse velocity;

2. Output module (56).

The output module contains:

A device (57) for measuring the output transverse speed and a device (58) for measuring the output longitudinal speed.

Preferably, the exit lateral velocity measuring device and the exit longitudinal speed measuring device are arranged so that measurements are made in the same plane, called the exit measurement plane (59). This exit measurement plane is substantially perpendicular to the longitudinal axis (X) of the material in the transverse rolling device.

Device (60) for measuring outlet outside diameter.

Outside diameter measuring devices can be the rotary measuring device STEELMASTER SMR from ZUMBACH. The principle of this measurement device is based on optical measurement performed by the laser in rotation mode or in static mode.

The speed measuring devices can be laser measuring devices such as Polytec's LSV065 laser surface speed meter.

The input module (51) may include a device (54) for measuring the input longitudinal velocity. Preferably, the input lateral velocity measuring device and the input longitudinal velocity measuring device are located in such a way that the measurements are made in the same plane.

Claims (19)

bone, called the input plane (55) measurement. This input measurement plane is substantially perpendicular to the longitudinal axis (X) of the material in the transverse rolling device. This means that measurements are taken at pipe surface locations located in the specified measurement plane. This feature enables accurate measurements. The input module (51) may include an inlet outside diameter measuring device (55) to automatically obtain and process the outside diameter of the inlet product, even if the outside diameter of the inlet product, such as a billet, is generally known. According to one aspect, the lateral velocity measuring device and the longitudinal velocity measuring device, and the outside diameter measuring device, the outlet or the inlet device, respectively, are located such that the locations or surfaces where the laser beams are measured are in the same plane. , orthogonal to the central line, called the input or output plane (55; 59) of the measurement. This means that the velocity measurements and the OD sleeve measurements are made in the same plane. The advantage is that the accuracy of the calculation of the angle of twist is increased. The measurement planes (inlet and outlet) should be located as close as possible to the roll gap. The method is predominantly non-destructive. This method works for all grades of steel or any type of material, and it also has the advantage that it works for any size option, for any outside diameter of the workpieces and any outside diameter of the pipes produced, and thus also for various types of ratio between the outer workpiece diameter and outer diameter of the sleeve. In addition, this method can be used for each individual pipe produced and is not intended for specific pipes. Tests were carried out to check the effect of rotation and axial movement of the rolled product on measurement accuracy. First, an imprint was made on a cold pipe while moving slowly at the first axial speed, and measurements of the outer diameters were taken. The experiment was repeated with a second longitudinal speed which is higher than the first longitudinal speed. The impact on the outside diameter measurement was not significant, as a difference of 0.05 mm was found for an outside diameter measured between 89.1 and 89.3 mm. Tests were carried out with different rotation speeds. The tests showed no significant effect on the average value of the measured outer diameter. The angles of twist can be calculated at several locations along the sleeve. The average twist angle can be calculated based on different twist angles at different locations along the sleeve. CLAIM 1. A non-destructive method for determining the angle of twist of the output product during the rolling of the input product into the specified output product, including the following steps: measuring the input rotation speed of the input product during said rolling; measuring the output rotation speed of the respective output product during said rolling; measuring the longitudinal exit velocity and/or longitudinal inlet velocity of said respective outlet and/or inlet; determining a rotation delta based on the specified input rotation speed and the specified output rotation speed; determining a twist angle based on said spin delta and said longitudinal exit speed and/or longitudinal input speed. 2. The method according to the previous paragraph, characterized in that it further includes the step of measuring the exit outer diameter of the output product. 3. The method according to claim 1 or 2, characterized in that the input rotation speed, output rotation speed, longitudinal output speed and/or longitudinal input speed are measured from the start time (t ₀ ) to the end time (ti). 4. The method according to claim 1 or 2, characterized in that the input rotation speed is measured from the intake start time to the intake end time, and the output rotation speed is measured from the exhaust start time and exhaust end time, while the indicated intake start time and the inlet end time determines the inlet time window, the specified outlet start time and outlet end time determine the outlet time window, and the inlet time window and the outlet time window have a common time window having a start time (t ₀ ) and an end time (t ₁ ). 5. The method according to claim 3 or 4, characterized in that the angle of twist (TA) is determined by the formula (F) - 6 042503 TA ₌ 3^(251^^2^) Jt ₀ ^V »T where Delta is the difference in the number of revolutions between the number of revolutions of the output product and the number of revolutions of the input product in the time window from the start time t ₀ to the end time t ₁ or in the general time window; ODH is the outer diameter of the output product; VHT is the longitudinal exit velocity of the output product. 6. The method according to claim 5, characterized in that the longitudinal exit speed VHT is changed to the longitudinal input speed V _BT multiplied by the elongation factor ke. 7. A method according to any one of the preceding claims, further comprising the step of measuring the inlet outside diameter of the inlet product. 8. A method according to any one of the preceding claims, characterized in that the exit velocity measurements and the exit outside diameter measurements are made in the same plane orthogonal to the axis of the exit product. 9. Method according to claim 7 or 8, characterized in that the inlet velocity measurements and the inlet outside diameter measurements are made in the same plane orthogonal to the axis of the inlet product. 10. Method according to any one of the preceding claims, characterized in that the start time (t ₀ ) and the end time (t1) are selected in the steady state phase. 11. A method according to any one of the preceding claims, characterized in that the rolling operation is a piercing operation, and wherein the input product is a blank and the output product is a sleeve. 12. The method according to any of the preceding claims, characterized in that the rolling operation is an elongation operation, and in which the input product is a sleeve and the output product is a thin-walled sleeve. 13. A device for non-destructive determination of the angle of twist during rolling of the input product into the output product, comprising: the first input sensor configured to measure the speed of the input product; the first output sensor, configured to measure the speed of the output product; sensor (60) outlet outer diameter; an electronic device configured to determine the twist angle of said output product based on measurements taken by said sensors during rolling. 14. The device according to claim 13, characterized in that the first output sensor (58) is configured to measure the transverse output velocity of the output product, and the device further comprises a second output sensor (57) configured to measure the longitudinal output velocity of the output product . 15. Device according to any one of claims 13, 14, characterized in that the first inlet sensor (53) is configured to measure the transverse inlet velocity of the inlet product. 16. The device according to claim 15, further comprising a second inlet sensor (52) configured to measure the longitudinal inlet velocity of the inlet product. 17. The device according to any one of claims 13-16, characterized in that it further comprises an inlet outside diameter sensor (54). 18. The device according to claim 17, characterized in that the first input sensor (53), the second input sensor (52) and the input outer diameter sensor (54) are positioned so that measurements are taken in the same input measurement plane (55). 19. Device according to any one of claims 14 to 18, characterized in that the first outlet sensor (58), the second outlet sensor (57) and the outlet outer diameter sensor (60) are positioned so that measurements are taken in the same outlet plane (59 ) measurements. -