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Research status of straightness measurement method of large diameter stainless steel pipe at home and abroad

Time:2022-03-18 Source:China Wuxi JiaNuo Special Steel Co.

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Research status of straightness measurement method of large diameter stainless steel pipe at home and abroad

Most of the traditional straightness error measurement methods are based on the contact method, are for the detection of small stainless steel pipelines. Domestic and foreign common stainless steel pipe straightness measurement methods are the following: lever method, indicator method, no diffraction light Mohr stripe detection method, integrated gauge detection method, optical axis method, step meter method, interferometric method, angle difference method, etc.. Through the analysis of the above several small steel pipe straightness measurement methods, it can be derived. They are measured and recorded data and processing data results to obtain the straightness error value, and are measured for the straightness error in a given plane. The measured range is complex and is not applicable to the straightness measurement of large-diameter stainless steel tubes. The status of research on straightness measurement of large diameter stainless steel tubes and other large workpieces at home and abroad is as follows.

In 2001, the State Key Laboratory of Precision Test Technology and Instruments of Tianjin University used semiconductor laser diodes and multiple sensors to measure the cross-sectional information of large-diameter stainless steel tubes for straightness measurement. The principle is to obtain the three-dimensional spatial coordinates of multiple cross-sectional dimensions and cross-sectional centers by image sensors, and then synthetically obtain the curvature center coordinates and the center axis, and finally perform error evaluation to obtain the straightness error. The outstanding advantages of this measurement method are large range, non-contact, fast measurement speed, good system flexibility, etc. However, due to the limited number of sensors, only three to five, limited sampling points, can not reflect the overall situation of the large diameter stainless steel pipe body, the measurement accuracy is limited. Measurement data is processed by computer, image sensor with laser, the cost is high.

Jilin Beijikai Drive Shaft Co., Ltd. measured the straightness of seamless steel tubes for welding of miniature car drive shafts in 2006. The method used was to determine the relative position of two parallel planes according to the diameter of the steel tube and the maximum allowed straightness error value, so that the distance between the two parallel planes was equal to the sum of the diameter of the steel tube and the maximum allowed straightness error value. The lower surface of the parallel forms a certain inclination angle with the horizontal surface. In the self-locking range to avoid slippage, allowing large-diameter stainless steel pipe rolling in two planes. If the rotation diameter is less than the distance between the two parallel planes, the straightness is considered qualified and they can smoothly pass through the two parallel planes and enter the holding area, while the opposite is unqualified, as shown in the schematic diagram as shown in Figure 1.3. The outstanding advantage of the method is the measurement principle is simple and easy to use, but its disadvantage is the low measurement accuracy, contact measurement, can not achieve the measurement of large diameter stainless steel pipe axis straightness, the quantitative measurement of steel pipe straightness, but also not conducive to batch testing of steel pipe.

In 2008, Lanzhou University of Science and Technology program materials science and engineering Wang Hong and others carried out a “virtual instrument-based large diameter welded pipe form error detection system” research, the measurement principle diagram as shown in Figure 1.4. principle is: to overcome the motor 1 through the corresponding drive mechanism to drive the measured large diameter stainless steel tube rotation. Sensor group 4 is installed on the fixed plate 5, fixed plate 5 can be moved along the large diameter stainless steel tube axial guide slider, so that when the large diameter stainless steel tube rotation, sensor measurement group along the steel tube axial movement, spiral collection of the shape and position of the steel tube surface parameters. Three displacement sensors are placed in the axial direction of the steel tube, collecting the bus data of the large diameter stainless steel tube, measuring the bus straightness, measuring the roundness of the steel tube with the other three sensors, the data collected by the displacement sensors are transmitted to the PC Wenzhou stainless steel tube for processing, to get the straightness and roundness error

In the international study of straightness measurement, the limit of high precision and ordinary accuracy is 0.5 m/m, higher than 0.1 m/m is considered the world’s leading, the United States, the National Bureau of Statistics Lawrence National Laboratory, Japan University and other experimental institutions of international research level more than 0.1 m/m. Of course, the straightness error of large diameter stainless steel pipe does not need to reach the above high precision level. Generally speaking, the straightness error of large diameter stainless steel pipe accuracy requirements in the range of 1-2m/m. Foreign straightness measurement of large workpieces such as high-precision guide rails has been a lot of research, the accuracy of the methods used has been greatly improved. However, most of these methods are applicable to the straightness measurement of the workpiece plane direction, not applicable to the straightness measurement of large diameter stainless steel pipe axial.

In 2006, Japan’s Tohoku University and the Korean Institute of Science and Technology jointly studied the “double guide parallelism and straightness of ultra-high accuracy measurement. Wenzhou stainless steel tube manufacturer it uses three high-precision displacement detector ADE 3401, placed on a sliding platform, detector P1 and PZ for measuring parallelism, detector P3 for measuring the straightness of the guide. A laser interferometer (Agilent 5529A) is used to measure the deflection angle of the sliding platform. The algorithm effectively eliminates the measurement error caused by the tilt of the measurement stage and achieves an experimental straightness accuracy of 0.05 um. The measurement schematic is shown in Fig. 5 (a) and the measurement setup is shown in Fig. 1.5 (b). The outstanding advantage of this measurement method is the high measurement accuracy, which has reached the international leading level in the field of straightness measurement. However, its disadvantage is that the process measurement is more complex, and its scope of application is mainly the measurement of high-precision guide, not applicable to the bulk straightness measurement of large-diameter stainless steel tubes in this subject. It is also difficult to measure the straightness of the spatial axis of the steel pipe with this method.