How to measure the length of a straight seam steel pipe?

Straight seam steel pipe(A53 ERW pipe) is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Generally divided into metric electric welded steel pipes, electric welded thin-walled pipes, transformer cooling oil pipes, etc., straight seam steel pipes have simple production technology, high production efficiency, low cost, and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam steel pipe. Welded pipes with larger pipe diameters can be produced with narrower billets. Welded pipes with different pipe diameters can be produced under the same billet width. However, compared with equal-length straight seam pipes, the weld length is increased by 30% and 100% respectively. %, the production speed is lower. Next, I would like to introduce how to measure the length of straight seam steel pipes.

According to the different process requirements of the manufacturer, the straight seam steel pipe length measurement system has a variety of length measurement methods, mainly the following types:

1. The grating ruler length measurement method, the basic principle is: two fixed-length grating rulers are set on the outer side of the straight seam steel pipe, and the grating rulers at both ends of the steel pipe are driven by a rodless cylinder, and the length of the straight seam steel pipe is measured by the phenomenon of light interference. , Has the characteristics of high precision, but the grating ruler is expensive, difficult to maintain, and sensitive to the influence of dust and on-site vibration.

2. The camera length measurement method. The camera length measurement is achieved by image processing to measure the length of the steel pipe. The principle is to install a series of equidistant photoelectric switches on one section of the straight seam steel pipe conveying roller, and add a light source and a camera on 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 taken by the camera on the screen and the photoelectric switch. The feature is that online measurement can be achieved. The length data can be obtained when the steel pipe passes through the measurement area without intervals. The disadvantage is that if there is no special light source, the steel pipe will be interfered by external light. After the special light source is used, the pipe end will be chamfered. The rear brightness is high, and the reflection of light is strong, which is easy to cause reading errors.

3. The encoder length measurement method, the principle is to install the encoder at the cylinder, use the cylinder to promote the movement of the steel pipe on the roller table, and install a series of equidistant photoelectric switches on the other side, when the steel pipe is hit by the photoelectric switch at the tube end driven by the cylinder When measuring the length of the cylinder, the cylinder stroke can be calculated from the recorded encoder readings to calculate the length of the steel pipe. The characteristic is that the steel pipe needs to be raised when measuring the length. In addition, there are some errors in the photoelectric switch detection, which may require sufficient measurement.

4. The improved encoder length measurement method is an indirect measurement method. By measuring the distance between the two ends of the steel pipe and the respective reference points, the length of the steel pipe can be indirectly measured. This measurement method overcomes the complex environment of the production site, the large volume of the steel pipe, and the measurement The mechanism cannot cross the support platform under the steel pipe. It is easy to operate, the measurement accuracy is less than ±10 mm, and the repeatability is ≤5mm.

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