Tyre Geometry Measurement at highest level
Tyre uniformity grading is standard practice today and machines are available to measure and grade 100% of tyres in production. Mass and stiffness variations on a tyre circumference cause radial and lateral force deviations which can be measured and graded.
The geometrical inspection of a tyre is now also becoming an important test and a run-out analyses is being increasingly recommended by many of the known OEMs. Radial and lateral run-out is the geometric variations in the tyre tread and sidewalls with respect to the nominal values. Test systems made by inmess offer a wide variety of testing procedures required by different tyre manufacturers to make tyres better and to ensure that only high quality and safe tyres are produced. Tyres and wheels are one of the most important components of a vehicle. The importance of safety and an increased focus on quality is becoming increasingly evident.
Determination of the radial and lateral force variations in a rolling tyre, its ply steer and conicity as well as the radial and lateral run-out is a prerequisite for substantial statements about the current quality level of a tyre production site. Geometrical measuring can be added as an additional feature to a tyre uniformity measurement machine or to a dynamic balancing machine.
At first glance, the laser measurement process seems to be simple and manageable, a distance measurement which gives an instant insight into the radial and lateral run-out of the measured tyre. Nevertheless, the steady development in the field of tyre design represents a challenge in the measurement and calculation of the run-out error of a produced tyre. A detailed analysis of the tyre sidewall and tread profile is a prerequisite for the design of the evaluation method. The main challenge lies in the development of an algorithm and applied filtering of the recorded measurement data. Ideally the run-out calculation should be applicable to any produced tyre. The development of a common software will remain a challenge to the industry.
Beside the classical measurement of the radial and lateral runout, the detection of bumps and dents is important criteria for the exclusion of low quality tyres during a production process. Even well-known companies which are specialized in optical technology still have difficulties to provide such a stable system in a real production line environment, where cycle time and repeatability of the detection play a major role. A great experience is required in the field of the tyre industry to ensure a reliable identification of bumps and dents. inmess recognized early that the identification of dents in the sidewall is very important for the safety and quality grading of a tyre. The first inmess uniformity measurement machines equipped with a geometric measuring was delivered for complete wheel production in the nineties to a well-known OEM, the machine was set up to identify dents and bumps on the tyre.
Picture 2: Detection of bumps and dents at the tire.
Modern measuring systems based on optical sensors like the ones inmess is using, offer great capabilities to scan and recognize the design of a tyre. Hatching and label patterns can be illustrated with such systems and using an appropriate image processing software. inmess invest heavily into testing sensors from different suppliers. The difficult environmental conditions in a production site have to be considered as well as temperature and air humidity. Only this way can the high quality standards which are expected from the customers can be reached under production conditions.
inmess have gained a great amount of experience, especially in the last years, in the field of optical measurement technology. The company’s newly developed rim run-out tester which was launched to the market in 2015, is another good example of inmess’ state of the art approach. The use of laser triangulation sensors instead of conventional measuring rollers was nothing other than trendsetting. Users are able to get a full 3D model of the rim in order to conduct quality inspection comparisons between the 3D design model and the real measured wheel. The knowledge inmess gains out of these projects as well as other projects within the automotive industry are used to continue to further improve the tyre uniformity measurement machine.