2 years ago

WORLD OF INDUSTRIES - Industrial Automation 1/2017

  • Text
  • Industrial
  • Automation
WORLD OF INDUSTRIES - Industrial Automation 1/2017

Multisensor system

Multisensor system checks engine mold production When liquid iron or aluminum is cast for an automotive engine block, temperatures can exceed 1,000 °C. In addition to its sweltering temperatures, the casting process is also time and cost intensive. To prevent incorrect castings, the SpinScan3D system checks the casting molds during quality control. SENSORS AND MEASUREMENT Whether at the push of a button or the traditional turn of a key, when the engine starts, the thrill of driving can begin. Cars exhibit engineering skill of the finest caliber: increasingly powerful engines and constant innovations that make driving ever more comfortable. But before a car can hit the road, it first has to take a long trip through production. The manufacturing process is complex and subject to the highest standards of precision: from the smallest screw to the entire body, everything has to be right, down to the last detail. Engine as centerpiece The engine is the car’s central component, and its quality must be 100 % compliant with the design data. An essential element of this centerpiece is the engine block. Whether made from cast iron or light metal, it is generally manufactured in a casting process. Once the cast material has hardened, it is virtually impossible to adjust the result. VMT therefore developed a solution that checks the quality of the mold using modern image processing technologies prior to the expensive and time-consuming casting process. Using this approach, the Pepperl+Fuchs Group company ensures that defective engine blocks are never cast in the first place. Fine grains, big blocks Due to the various point of views of the SpinScan3D we are able to provide a much more comprehensive data set and a high-precision 3-D-image of complex objects. Dr. Michael Kleinkes, Development Manager at VMT Vision Machine Technic Bildverarbeitungssysteme GmbH, a subsidiary of Pepperl+Fuchs The casting process is based on a natural material that we otherwise associate with deserts and beaches: sand, pressed and supplemented with a binding agent, serves as a “lost mold” for the manufacture of heavy engine blocks. These sand cores form a negative of the engine block and fill the later cavities during casting. After the casting material hardens, they are destroyed again and used to produce new molds. Each individual engine block is thus created using its own sand mold. Since the quality of the sand core has a significant influence on an engine block’s characteristics, quality assurance must start before casting. Due to the large number of engine blocks manufactured daily, however, checking each sand core individually would require considerable effort. A solution is therefore required that automatically examines the sand cores in detail and can simultaneously determine if they are fit for casting or not. The challenge lies in the complexity Dr. Werner Neddermeyer, Project Manager at VMT, recognized the problems in engine block production and developed an idea. “We considered the measurements that need to be recorded and how we could achieve this using our sensors,” he says, describing the initial stages. “Every point within the sand core must be checked very precisely to make a statement on its quality. This is not easy, considering that sand cores for engine blocks are complex molds.” The proven light section process quickly proved to be the appropriate technology for examining the sand cores in detail. However, an ordinary light section sensor was not sufficient to record and depict a sand core in all its details. The complexity of a sand core required a more sophisticated sensor system that could examine and check every corner - a challenge that Neddermeyer took on together with Dr. Michael Kleinkes, Development Manager at VMT. The result is a sophisticated interplay of multiple systems that provide a precise 3 D image of each sand core and automatically compare it with the CAD design data. SpinScan3D Sensor Symbiosis The solution uses four SpinScan3D sensors that work in parallel. The movement and interaction of the individual components of this multi-sensor system are what allow for the exact imaging of Down to the smallest detail: With rotating movements of the SpinScan3D, four perfectly coordinated sensors create a detailed image of the sand core and hence data for the casting mold WORLD OF INDUSTRIES – INDUSTRIAL AUTOMATION 1/2017

All a question of perspective Due to the rotating movement of the SpinScan3D, the viewing angle of the object is constantly changing at a measuring rate of 300 light sections per second, which results in a multitude of individual snapshots. The intelligent VMT software processes all recorded data, assembling the countless individual images into a point cloud to create a three-dimensional overall image of the complex form. The reproduction is practically free of shadowing effects. This means that the SpinScan3D records and depicts almost every millimeter precisely. “While subsections of an object might not be recorded by traditional laser-line triangulation because they lie in the measurement shadow, the different viewing angles of the SpinScan3D enable it to detect more points,” explains Kleinkes. “We therefore provide a much more comprehensive data set and a high-precision 3 D image of complex objects.” Thanks to the four perfectly coordinated sensors working in parallel, the VMT system can accurately record even the geometry of the large sand cores used for engine block casting. And the system works so quickly that it does not hold up the pace of production. Data processing is the answer the complex molds. A look inside the SpinScan3D reveals how VMT has modified the laser-line triangulation for this task. As in the traditional light section process, an optical prism is used to expand a laser’s light beam into an evenly luminous line. Two cameras in the SpinScan3D that work in parallel each examine a specific part of the laser line and record the height profile along it. This double laser-line triangulation allows for an expanded measuring range without sacrificing measurement accuracy. The particular innovation of the SpinScan3D ultimately lies in the expansion of the sensor to include a motion axis. It is turned by a rotation platform so that the laser inside rotates around its own axis and the projected line runs over the object without interruption. During this process, the two cameras swing around the midpoint of the sensor and continuously record changes to the laser line. Such precise checks are made possible by the VMT software. It processes the large data volume with ease and not only provides the user with a detailed image of the sand core, but automatically performs a comparison with the CAD design data for the casting mold. This is done by determining reference points for critical locations of the sand core. The software compares the recorded sensor data with the defined target dimensions and calculates the extent to which the virtual plan and the actual design agree. “This process, which brings together the virtual world and the real world, reflects the need for Industrie 4.0 components to provide electronically readable data from all phases of the product life cycle,” Neddermeyer explains. If the quality of the sand core differs significantly from the CAD drawing, a warning message is automatically sent to the control center so that the defective casting mold can be removed before the casting process. The system thus provides the user with all information needed before the casting process in a form that enables the necessary measures to be determined immediately. Photographs: Pepperl+Fuchs About Pepperl + Fuchs Pepperl+Fuchs is a worldwide company with its headquarters in Mannheim, Germany. They manufacture products for Factory and Process Automation and are specialists in sensor manufacturing. With revenues more than € 500 million and nearly 5,600 employees world wide (2015), the company has more than 40 foreign subsidiaries on six continents, and manufacturing facilities. WORLD OF INDUSTRIES – INDUSTRIAL AUTOMATION 1/2017


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