Visual 3D measuring technique

For the fast three-dimensional acquisition of surfaces Fraunhofer EZRT is mainly employing light-section techniques. This technique is very advantageous for moving objects. Extensive knowledge is present for applications for tire manufacturing, the testing of mounted tires and wheels and the inspection of sealing rings for braking systems.

In light-sectioning a light-section is projected onto the object and this light-section is then recorded by a camera positioned under a different angle from the projection direction. From the course of this light-section a height profile is generated. By moving the object through the light-section the entire surface can be acquired. Shadowing effects can be overcome by applying multiple cameras or lasers.

Light-sectioning is especially suited for the fast three-dimensional acquisition of the surface of a specimen. Even when a lateral resolution of 0.05 mm is required, velocities of about 1 m/s are possible, with the height resolution then being in the µm regime. By applying suitable preprocessing, structures with a height deviation below 1 µm can be detected.

System solution TireChecker

Description

The internationally patented TireChecker system is consisting of one or several laser light-sectioning sensors and a specialized PC based evaluation software enabling geometry measurements at high velocities. The software can acquire bumps, lateral contractions and radial and axial runouts with high speed and reliability. By using line lasers the measuring of tires becomes possible also on complex surfaces like letterings or symbols. Thus, the extension of bumps and lateral contractions can be determined in all three dimensions.

In light-sectioning a light-section is projected onto the surface of a tire and monitored by a specialized camera under an angle from the projection direction. From the course of the light section a height profile is generated. By rotating the tire within one second thousands of height profiles of the surface are recorded.

Tailor-made solutions

Our strength is due to our flexibility: in close cooperation with the customer we are developing solutions for individual requirements. For machine manufacturers we are offering the adaption of the entire measuring system to the tire inspection system as well as the reproduction of the system under license. Sensors and software can be adapted to individual and specialized tasks if required. In cooperation with our partners even entire testing systems for new measurement tasks can be realized.

Due to our long-time experience in sensorics and image processing we are capable of directly applying latest research for industrial purposes and thus transferring latest technologies to application. The continuous system development enables TireChecker to remain the optimal measuring system for tire geometry.

Performance features

  • Cycle times below one second
  • Precise geometry and bump measurement on one or both side walls and optionally tread
  • Measurement tracks can be set up individually for each tire
  • Bump measurements also on structured surfaces and letterings
  • No reference data acquisition necessary
  • Can be flexibly adapted to various inspection systems
  • Offline evaluation of saved data possible

System solution SpliceChecker

Description

In tire manufacturing different material layers are rolled up onto a drum, thus the tire is built up layer by layer. For tire quality and safety it is necessary for the start and end of each layer to have a defined overlap.

Up to now, for the determination of this overlap, systems capable of acquiring only one track are employed. The Fraunhofer EZRT development SpliceChecker is applying light-sectioning techniques in order to inspect layer setup along the entire width and circumference for the first time. As a result of this measurement not only the overlap is determined but also a possible lateral offset of the layer with regards to its desired position. Optionally, it can also be determined, whether the layer has been deposited at all or if a material with incorrect width or thickness was used. Also production flaws like folded corners (“dog-ears”) or foldings can be detected.

In light-sectioning a light-section is projected diagonally towards material layer onto the drum and monitored by a specialized camera under an angle from the projection direction. From the course of the light section a height profile is generated. During tire buildup up to 8000 height profiles of the material layer are recorded. This enables tire buildup inspection even at layer deposition velocities of 120 m/min.

Tailor-made solutions

The current SpliceChecker systems are acquiring the layer buildup on a width of 400 mm or 700 mm resp. Under development is a modular system capable of acquiring a layer width of up to 1000 mm with just one camera. Measurement speed and resolution are adapted to the individual requirements of our customers. By coupling with existing machine controls an integration into existing manufacturing systems is possible.

Performance features

  • Data acquisition during layer buildup
  • Suitable for all material layers (Innerliner, Ply, Breaker, etc.)
  • Usually no additional cycle time required
  • Measurement of the entire material layer
  • Precise determination of splice (overlap/open) throughout the entire width
  • Determination of material width and offset throughout the entire winding
  • Customer specific evaluation possible
  • No reference data acquisition necessary
  • Can be flexibly adapted to various tire systems
  • Offline evaluation of saved data possible

Application fields of visual 3D measuring technology

  • Measurement of tires
  • Quality control of tires

Advantages and customer value

  • Very low cycle time, usually below one second
  • Individual, customer-adapted systems
  • No reference data acquisition necessary
  • Can be flexibly adapted to various systems
  • Offline evaluation of saved data possible