Why visual rope inspection?
The visual inspection of steel ropes is stipulated by law in many applications and is usually carried out by two employees who check the rope as it passes them by at an inspection speed of less than 0.5 m/s.
This leads to hazards, stresses and strains from the immediate vicinity to the moving rope. Other problems exacerbate the inspection task:
- unergonomic working posture
- poor lighting conditions
- weather conditions, e.g. cold temperatures, rain and wind
- high concentration requirements
The development began with a prevention project called "visual rope inspection" by the Employer's Liability Insurance Association for the railway, tram and metro sector in order to provide technical support to reduce the hazards, stresses and strains. In this context, the Institute of Mechanical Handling and Logistics (IFT) at the University of Stuttgart developed a practical prototype with professional support from VDS e.V. Following gradual optimisation of the technology, Winspect Deutschland GmbH now offers a robust system under licence from the IFT for precise, safe and economic inspection of your wire ropes.
The circumference of the rope is recorded completely by four cameras under strong but energy-saving LED light with a resolution of 0.1 mm pixel; the results are then saved in digital form. This is followed by semi-automatic evaluation to ascertain rope damage, e.g. wire breaks, detecting deviations in the rope structure as damage: corresponding output is then produced.
Viable recording quality depends on the rope running smoothly with a dry, visible rope surface. Just as with the human eye, the camera's view of the rope surface is hindered by films of lubricant and coats of paint.
The recorded image data are automatically examined by the computer for any deviations from the normal rope structure. The detected anomalies are evaluated and classified at a computer screen under the responsibility of the operations manager. This is a local procedure which is completely separate from the data recording process: it can be interrupted and also repeated at any point in time.
As a result, the inspector does not have to judge the entire surface of the rope but only those points which deviate from the normal rope structure. The result of the inspection consists in an inspection report that features the flaws in the rope detected by the system and then judged and evaluated by the user, stating the rope meter number.