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Analysis of Length Measurement Method of Seamless Steel Pipe

Date:2020-03-20    keywords:seamless steel pipe,length measurement
1. Gage length measurement
The basic principle is: two fixed-length grating rulers are set on the outer sides of the two ends of the seamless steel tube, and the rod ruler is used to drive the grating ruler near the two ends of the steel pipe.
It is characterized by high accuracy. However, encoders are expensive and difficult to maintain, and are sensitive to the effects of dust and site vibration.

2. The camera measures the length.
Camera length measurement uses image processing to measure the length of straight seam steel pipes. The principle is to install a series of photoelectric switches at an equal distance on a certain section of steel pipe conveyor rollers, and add a light source and a camera to the other section. When the steel pipe passes through this area, the length of the steel pipe can be determined according to the position of the image on the screen captured by the camera with a photoelectric switch.
The characteristic is that online measurement can be realized, and the length data can be obtained when the steel pipe passes through the length measurement area without interval. The disadvantage is that if the special light source is not used, the steel pipe will be disturbed by external light. However, after using the special light source, the large-diameter straight seam steel pipe has a high reflection of the light at the end of the pipe after chamfering, and it is easy to reflect light, cause reading errors.

3. Encoder length measurement
Principle: Install an encoder at the oil cylinder, use the oil cylinder to move the thick-walled steel pipe on the roller table, and install a series of photoelectric switches of equal distance on the other side. The recorded encoder readings are used to convert the cylinder stroke, so that the length of the steel pipe can be calculated.
The characteristic is that the steel pipe needs to be raised when measuring the length. In addition, there is a certain error in the photoelectric switch detection. The characteristics of spiral steel pipes may need to be fully measured.

4. Improved encoder length measurement
This method is an indirect measurement method, which measures the length of the steel pipe indirectly by measuring the distance between the two end faces of the steel pipe and their respective reference points. A length measuring trolley is set at each end of the steel pipe, the initial position is zero, and the distance is L. Then move the editor length to the walking distance L2, L3) of the respective steel tube ends, L-L2-L3, which is the length of the steel tube.
This measurement method overcomes the difficulties of the huge volume of steel pipes, the complex production site environment, and the inability of the measurement mechanism to pass through the lower supporting platform of the steel pipes. This method is easy to operate, the measurement accuracy is within 10mm, and the repeat accuracy is ≤5mm.

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