According to the different requirements of the production process of the oil casing pipe, the length measurement system of the oil casing also has a variety of measurement methods. Let us look at the basic three measurement methods.
1. Length measurement with grating ruler
The basic principle is to install two fixed-length grating rulers on the outer side of the oil casing pipe. The rod-shaped cylinder is used to drive the grating rulers near the two ends of the oil casing pipe. The length of the oil casing pipe is measured by the phenomenon of light interference.
It has the characteristics of high precision. However, grating rulers are expensive, difficult to maintain, and sensitive to dust and site vibration.
2. Camera length measurement
Camera length measurement is achieved through image processing. The principle is to install a series of equidistant photoelectric switches on one section of the oil casing conveying roller, and add a light source and a camera on the other section. When the oil casing pipe passes through this area, the length of the oil casing pipe can be determined according to the position of the image taken by the camera on the screen according to a photoelectric switch.
Its feature is that online measurement can be achieved, and length data can be obtained when the elbow passes through the length measurement area without interval. The disadvantage is that if no special light source is used, the elbow will be interfered by external light. After using a special light source, due to the high brightness of the curved end of the petroleum casing, the light reflection is very strong, which may easily cause reading errors.