Pipe end defect detection and wall thickness detection of steel pipes

1. Pipe end defect detection

1.1. Large-scale defect detection at the pipe end

After the steel pipe is sized by the sizing machine, the end of some steel pipes will have wrinkles and collapse inward, which will cause the laser probe of the pipe end wall thickness measuring device to be unable to extend into the steel pipe.

Use industrial camera shooting and image processing technology to detect pipe end defects. The image processing method is to identify whether there is a section of collapsed pipe wall in the inner hole of the steel pipe and the size of the collapse under the statistical model, and then determine whether the pipe end needs to be sawed.

1.2. Wall thickness defect detection

Through the pipe end defect detection introduced in 1.1, the measuring end of the laser thickness gauge can pass through the port of the measured pipe, thereby realizing the detection of wall thickness defects.

After the steel pipe is rolled, there will be defects such as uneven wall thickness at both ends of the pipe, so each steel pipe must cut off a part of both ends. Since the length of the defective pipe end of each pipe is different, it is difficult to determine the specific cutting length when cutting. The laser thickness gauge uses the laser principle to measure the wall thickness of the steel pipe end, which can complete this part of the work. It can determine the length of the defective pipe end by continuously detecting the wall thickness and marking the boundary between the defect and the qualified part through the marking machine to provide a dimensional basis for the pipe-cutting process.

2. Equipment composition

Because a steel pipe has two ends to be measured, two measurement systems need to be installed at the same time.

The two defect measurement devices are located at both ends, and the measurements are performed in sequence at different positions. After the two devices complete the measurement, they need to communicate with each other to unify the measurement data to the same steel pipe number and transmit the measurement data to the overall information management system for easy query and later tracking.

Conclusion

This paper designs and implements a non-contact automatic measurement system for the wall thickness of steel pipe ends, and accurately measures the defect position and marks it. The system uses a turntable to drive the laser displacement sensor to rotate around the central axis of the steel pipe to measure the wall thickness of the entire circumference of a section of the pipe end. At the same time, the translation table automatically adjusts the distance between the measuring section and the pipe end, the large lifting table adjusts the pipe center alignment height, and the double-arm translation table adjusts the measurable pipe diameter range, realizing non-contact automatic measurement of pipe diameters of various specifications of steel pipes. The use of laser thickness gauges brings great convenience to the measurement of wall thickness and also brings convenience to defect detection.