# New On-Line MFL Testing Method and Apparatus for Winding Mine Hoist Wire Rope
## 4 Key Techniques of the Method  
On site, an on-line testing device is needed to send the open-loop permanent magnetization probe to the WMH wire rope so that the axis of the probe is aligned with the axis of the wire rope and it can float to track the movement of the wire rope in different directions. It is therefore designed to work in conjunction with the telescopic cylinder (electric cylinder) to bring the probe into the appropriate position; the working principle of this device is shown in Figure 16. The detection device is mainly composed of an inspection probe for opening and closing with clutch, a lifting cylinder (electric cylinder) and a rocker arm. At first, the lifting cylinder (electric cylinder) and the rocker arm will raise the probe to a specific position such that the probe axis coincides with the wire rope axis. The testing probe is controlled by a cylinder (electric cylinder) that slides the two parts of the probe along parallel linear guide rods to close or open them so that the probe is looped or disengaged from the wire rope.  
The testing probe is closed to encircle the wire rope in the testing process and is driven by a floating tracking mechanism which allows the Y and Z degrees of freedom to be released so as to accommodate the vibration and wobble of the wire rope, thereby tracking the movements of the rope to detect. The floating tracking mechanism mainly consists of the first linear guide bar, bearing adapter plate, the second linear guide bar and the bottom plate, as shown in Figure 17. The testing probe controlled by the cylinder (electric cylinder) is installed on the first linear guide bar by the bearing, which is installed on the bearing adapter plate, and this part allows the testing probe to be freely moved in the Y direction. The bearing adapter plate is installed on the second linear guide bar by the bearing. The second linear guide bar is perpendicular to the first linear guide bar and is installed on a base plate connected to the rocker arm and the lifting cylinder (electric cylinder); this part can enable the probe to move freely in the Z direction. A spring is also connected between the bearing adapter plate and the bottom plate so that, on the one hand, the probe remains at the midpoint of the slide in the Z-direction of the tracking mechanism, and, on the other hand, the jitter amplitude in the Z-direction of the wire rope may be dynamically adjusted, cushioning and absorbing the changes in the attitude of the probe.  
Figure 16: On-line testing devices.  
The probe is fitted with wear sleeves at both ends and the floating tracking mechanism accommodates rope wobble in any direction by leaving a small gap between the wear sleeves and the wire rope. The inner diameter of the magnetic sensitive probe shoe in the probe is usually 2-5 mm larger than the inner diameter of the wear-resistant sleeve, and the wear-resistant sleeve is used with the magnetic sensitive probe shoe to detect the corresponding specifications of the wire rope by replacing certain specifications of the probe shoe and the wear-resistant sleeve so as to realize the magnetic sensitive probe shoe to keep the fixed lifting away and non-contact detection with the wire rope.  
The entity is machined and assembled according to the operating principle of the in-line testing device and the detection probe, as shown in Figure 18, and is mounted on a WMH wire rope running at high speed for real-time inspection.