In the automatic detection, the lift-off effect and stability testing of the coupling layer often becomes the most intractable problems. In the automatic detection, the lift-off effect and stable coupling layer is the main reason causing missed and false positives. Either missed or misreported all affect the reliability of detection. For a long time, in the automatic detection of the actual application, because of the lift-off fluctuations decreased detection reliability problems or coupling of the water layer thickness, this technology has been plagued by the normal use of the " bottleneck."
Typically, the way to solve the lift-off effects are: mechanical probe tracking method, the probe coil bridge connection, change detection coil LC circuit capacitor values and the use of multi-frequency detection technology. In addition to mechanical tracking method, other several solutions, through improved probes and instruments to be achieved, but only improved mechanical tracking probe holder, to prevent lift-off clearance changes. In practical industrial applications, the probe mechanical tracking method is the most commonly used to overcome the lift-off effect of impact. Common probe mechanical tracking mode, there are two: one is to limit use of roller and cylinder or spring pushing a combination of methods, the detection probe and check the surface to maintain a constant distance between. While this approach on the inhibition of the lift-off effect can play a better role, but also makes vibration and noise increase. Another, using mechanical tracking probe way is to use the measured distance the probe detection probe timely clearance liftoff fluctuation and a ranging signal to control and drive means to drive the stepper motor power detection probe moves to ensure probe was seized with a constant gap between the workpiece. This method is applicable to other flat sheet or billet scan testing, the disadvantage is due to mechanical action reaction rate is relatively slow, but also more complicated.
Probe the probe into a car, and to adopt two springs push method enables the detection probe and check the surface always maintained a certain distance. From the experimental results, the probe follower relatively strong, the basic guarantee of the probe is detected with a constant distance between the pipe surface, testing also achieved good results. Typically, the way to solve water coupling layer are: fixed sink boxes, stable water spray devices. As a result of rotation of the probe along the way steel, seamless pipe length is generally around 10m. Must therefore be considered stable water spray device, such as increasing the flow diameter of the mouth, the mouth and the lower flow pipe height, reducing spray. Current conventional solutions can only be so, but the effect of solution in an acceptable range.
