SU822939A1 - Method of measuring tube wall thickness - Google Patents

Description

(54) METHOD OF MEASURING THE PIPE WALL THICKNESS

I

The invention relates to the automation of pipe production and can be used on pilger mills.

There is a known method of controlling the thicknesses, the pipes, which measure the degree of absorption of penetrating radiation by the two walls of the pipe — the radiography of the pipe through two walls in diameter 1.

However, the known method is unacceptable for controlling the wall thickness of a pipe rolled in pilgrim mill rolls, since the axis of tubes, when rolled on a piligrimage mill, oscillates in different directions relative to the axis of rolling, and the length of a rolled pipe can reach 40 m and more.

Oscillations of the tube axis during its rolling with respect to the rolling axis occur when controlling the thickness by the method of tube penetration through two walls along the diameter, i.e. the offset of the axis of the penetrating radiation beam relative to the tube axis due to the curvature of the surface of the latter introduces an error as a result of measurement offset axes.

In practice, measuring the thickness of a pipe according to the method of x-raying through two walls is carried out either during the transportation of an already rolled pipe, but in this case, operational efficiency is lost, controlling the wall thickness, or aligning the radiation axis with the pipe axis using mechanical devices.

A known method of control of cylindrical products, including the penetration of penetrating radiation from the wall of the tube,

measuring the degree of absorption of penetrating radiation by the walls of the pipe; converting the measured value into an output signal proportional to the thickness of the stack of the pipe, containing the operation of combining the axis of the pipe with the axis of penetrating radiation 2.

However, it is difficult to measure the wall thickness of a pipe rolled in pilger mill rolls, since it is practically difficult to combine the axis of penetrating radiation with the axis of a hot pipe 360 mm or more in diameter, which oscillates with accelerations in different directions. The purpose of the invention is to simplify the method for measuring the wall thickness of a pipe during its rolling. The goal is achieved by the fact that in the method involving penetration by penetrating radiation of pipe walls, measuring the degree of absorption of penetrating radiation by pipe walls and converting the measured value into an output signal proportional to the wall thickness of the pipe, fix the calibration time of the rolled pipe section for each feed, converting the measured The degrees of absorption of penetrating radiation by the pipe walls are carried out only during this period of time for each feed. The necessity of fixing the calibration time span of the rolled pipe section for each feed and converting the measured degree of absorption of penetrating radiation into these fixed time intervals is due to the peculiarities of the piligrim pipe rolling, which consists in reciprocating movement of the pipe rotated through 90 ° when being fed, while oscillation relative to the axis of the penetrating radiation, it is cyclical. The axis of the rolled part of the pipe is below the axis of rolling, since the bottom of the output roller table is located below the bottom of the gauge rolls in the calibrating part of the stream. Therefore, when the liner is accelerated and rotated through 90 °, the axis of the pipe describes a part of the circumference relative to the rolling axis, the pipe thus moving forward. Then the metal is grabbed with a rim of a gauge and the main deformation of the metal takes place, while the pipe, rolling in the roll caliber, returns to the side, the reverse flow, and the pipe oscillations forcibly decay, as the end of the sleeve and the rolled part of the pipe are clamped along the same axis, and the pipe moves along the exit roller table of the pilger mill. At the next stage of rolling, the rolled section of the pipe is calibrated at the calibrating section of a roll of caliber rolls. The pipe oscillations are absent during this time interval, the pipe also rolls to the reverse side of B, the axis of the pipe coinciding with the axis of the conveyor of the piligrimage mill and, therefore, with the axis of the beam of penetrating radiation. The rolling cycle is then repeated with each subsequent feed. FIG. Figure 1 shows a graph of the wall thickness along the length of the pipe; in fig. 2 is a graph of the change in the output of the receiver of penetrating radiation in the course of continuous scanning of the corresponding sections of the pipe. FIG. 1, the pipe thickness is plotted along the ordinate, and the length along the abscissa. The graph schematically shows the order of the penetrating radiation beam relative to the pipe. Point O corresponds to the beginning of the pipe section, which is illuminated by penetrating radiation at the moment of time corresponding to the beginning of the delivery, to the end of the delivery, the pipe section is illuminated with the length OC. The CA section is illuminated when the rolled section is calibrated. moving in the opposite direction of flow. Then, the areas of BP, BE and SI are illuminated by penetrating radiation at subsequent feeds, and the sections of DW, EC - during subsequent calibrations of rolled pipe sections. FIG. 2, the value of the radiation receiver output signal is plotted on the ordinate axis, and time is plotted on the abscissa axis. The areas of the OS, AD, BE and SI are the changes in the output-i of the radiation receiver signal during the x-ray of the sections of the pipe OS, AD, and SI (Fig. 1). The CC, DD and EE sections are the values of the output signal of the radiation receiver, obtained from the translucent diameter of the pipe of the wall thickness in a small section of the pipe. The dimensions of this illuminated area are determined from the ratio of the speed of movement of the sleeve to the side, reverse flow, and the speed of movement of the deformable part of the pipe to the supply side, i.e. a small part of the pipe moves under the penetrating radiation beam. The sections CA, DV and EC - the change in the output signal of the radiation receiver when the sections of the pipe CA, DV and EC are illuminated (Fig. 1) when calibrating the rolled sections of the pipe for subsequent feeds. The dotted line indicates the areas of possible values of the output signal of the radiation receiver, due to tube oscillations when the tube sections are illuminated during the time the liner is fed into the pilger mill rolls and the time of the main metal deformation on the rolled section of the tube. The method is carried out as follows. During the time of supply by the source of penetrating radiation, a portion of the pipe OS is illuminated (Fig. 1). The output of the radiation receiver lies in the zone bounded by the OS section and the dotted line (Fig. 2). Then, the main deformation of the metal is carried out in the mill, the sleeve moves in the direction opposite to the reverse flow, and the pipe relative to the thickness gauge moves slightly due to the stretching of the rolled pipe section. The oscillations of the tube relative to the axis of the penetrating radiation are still preserved. therefore, the output of the radiation receiver also lies in the zone bounded by the CC section and the dotted line. The output signal of the radiation receiver, proportional to the true value of the thickness of the monitored pipe, is obtained only on the CA section (Fig. 2), since the pipe oscillates in this section are absent, and the pipe axis coincides with the axis of penetration, i.e., the measurement error is minimal. Then, for each rolling cycle that corresponds to the flow, deformation and calibration of the pipe, the output of the radiation receiver is repeated while respecting the proportionality of the measured wall thickness of the pipe section and the output signal of the radiation receiver. In the case of continuous conversion of the radiation receiver signal to the output signal of the instrument, a large measurement error is obtained, and when using the proposed measurement method, which converts the receiver signal to the output signal, only at intervals corresponding to the calibration of the rolled pipe section (CA, LW, and EC sections) the measurement error is the smallest .. Use of fixing the calibration time span of the rolled section of the pipe for each feed and

uh

MpySbijM length

and Fig. 1, the formation of the measured degree of absorption of penetrating radiation by the walls of the pipe carried out during this period of time for each feed favorably distinguishes the proposed method from the well-known fact that it does not require the additional time-consuming mechanical operation of combining the axis of the pipe with the axis of the beam of penetrating radiation. the wall thickness of the pipe rolled in the pilger mill rolls, including the penetration of the pipe walls by penetrating radiation, the measurement of the degree of penetration penetration radiation from the pipe walls and conversion of the measured value to an output signal proportional to the wall thickness of the pipe, characterized in that, in order to simplify the measurement, the conversion is performed during calibration of the rolled pipe section for each feed. Sources of information taken into account during the examination 1. USSR author's certificate No. 302597, cl. G 01 B 15/02, 1971. 2. USSR author's certificate No. 288308, cl. G 01 B 15/02, 1974. 3 E

Time with Fi.2

Claims (1)

Claim A method of measuring the wall thickness of a pipe rolled in pilger mill rolls, including scanning the penetrating radiation of the pipe walls, measuring the degree of absorption of penetrating radiation by the pipe walls and converting the measured value into an output signal proportional to the wall thickness of the pipe, characterized in that, in order to simplify the measurement, conversion produce during the calibration rolled section of the pipe for each flow.