Steel pipe end defect detection and wall thickness detection quickly obtain the size of the defective part of the steel pipe end

After rolling, 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. This article introduces how to know the defective part of the steel pipe end. Wall thickness measurement; steel pipes have hollow cross-sections, and their length is much greater than the diameter or circumference of steel. According to the material, they are divided into carbon structural steel pipes, low alloy structural steel pipes, alloy steel pipes and composite steel pipes; according to the use, they are divided into pipelines, engineering structures, thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high-pressure equipment, etc.; according to the production process, they are divided into seamless steel pipes and welded steel pipes, of which seamless steel pipes are divided into hot rolling and cold rolling (drawing), and welded steel pipes are divided into straight seam welded steel pipes and spiral seam welded steel pipes. The quality of the steel pipe end is the data that the steel pipe needs to detect, and the unqualified steel pipe ends need to be cut off, so this article mainly develops equipment that can realize steel pipe end defect detection and wall thickness detection.

1. Detection of defects at the end of steel pipes

1.1. Detection of large defects at the end of steel pipes: After the steel pipes are sized by the sizing machine, the ends of some steel pipes will wrinkle and collapse inward, which will cause the laser probe of the wall thickness measuring device at the end of the steel pipe to be unable to extend into the steel pipe. Industrial camera shooting and image processing technology are used to detect defects at the end of steel pipes. 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 end of the steel pipe needs to be sawed.

1.2. Detection of wall thickness defects: Through the detection of defects at the end of steel pipes 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 pipes are rolled, there will be defects such as uneven wall thickness at both ends of the pipes, so each steel pipe must have a part of both ends cut off. Since the length of the defective steel pipe ends 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. By continuously detecting the wall thickness, the length of the steel pipe end with defects is determined, and a marking machine is used to mark the boundary between the defect and the qualified part, providing 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. As can be seen from the above figure, 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, 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.

Summary: 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 a section of the steel pipe end. At the same time, the translation table automatically adjusts the distance between the measuring section and the end of the steel pipe, 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.