Inspection of sealing rings with iNSPEC 50 and VisionPro at iTech Engineering
In today's automotive injection pumps, fuel is pressed against sealed parts with incredible force at more than 2,000bar/29,000 pounds per square inch. This means that precision is the top priority when it comes to manufacturing sealing rings. The new iNSPEC 50 inspection system from iTECH Engineering AG based in Bettlach, Switzerland, guarantees flawless surfaces in the range of thousandths of a millimeter—and at a breathtaking speed.
For Hänggi GmbH, the renowned manufacturer of stamped parts, speed and accuracy are of prime importance when competing with other automotive component suppliers. Working in cooperation with iTECH Engineering AG, the company has now found a solution which improves parts quality and speeds up production processes. The iNSPEC 50 inspection system checks metal sealing rings for fuel injection pumps according to the criteria of surface quality and precise parts dimensioning. When inspecting the surface of the sealing rings the system is looking for scratches and contamination. The dimensional check measures the inside and outside diameter of the parts. iNSPEC 50 operates at a nominal test speed of two parts per second, i.e., 7,200 parts/hour and at a testing precision of four thousandths of a millimeter.
Complete image processing takes place using VisionPro® software from Cognex. This provides for the precise identification of fault characteristics and extremely fast transmission of control pulses for production.
Intelligent management, precise tracking
With iNSPEC 50, the parts are fed from a bulk magazine to a charging channel via a pot-type screw conveyor system. Here the sealing rings are separated and placed on the carrier device with gaps of approximately five centimeters. A glass ring with an outside diameter of 80cm is used to transport the parts to be tested to the downstream camera control stations.
The iNSPEC 50 checks the exact position of each sealing ring through precise synchronization of the time a part is set down on the glass with the rotational speed of its synchronous belt drive stepping motor. Throughout parts tracking, the position of the stepping motor ensures precise determination of the position of the individual sealing rings, i.e., the moment at which the camera is triggered. Any part which has not undergone inspection is always rejected by the iNSPEC 50 as a potential nonconformity.
At the first control station, a camera system with telecentric optics checks the geometric accuracy of the sealing rings. The parts are backlit from below with perfect contrast. The telecentric optics system was selected to eliminate any distortion. Both the outside and the inside diameter are measured at the first station.
In the picture with perfect lighting
The second downstream control station performs surface inspection of the face and outer sides of the sealing ring. Optimum contrast is ensured here by three-stage lighting: lateral dark-field illumination plus dome illumination with a center opening for the camera, as well as coaxial illumination, which is directed through the opening at the center of the part.
The strengths of VisionPro, the intelligent vision software with a robust tool library, also come into play at the lighting stage. VisionPro ensures the extremely fast transmission of image values. This vision software is designed to solely focus on critical features of the parts that are important for distinguishing between conforming parts and rejects. VisionPro ignores any variations in appearance that are noncritical. This eliminates the need for the laborious and time-consuming preprocessing of image data. The result is extremely fast parts handling and application development for new product requirements.
The third and final camera control station of the iNSPEC 50 examines the sealing rings from below. Inspection is performed as at the previous control station using an industrial camera, aided by dark-field, dome and coaxial illumination.
Once the final check has been made, the iNSPEC 50 blows the flawless sealing rings into one of ten parts bins in batches of 2,000. All parts which remain on the glass ring are automatically rejected at the end of the inspection process.
The iNSPEC 50, with its vertical lifting hood made of tinted plastic, proves to be highly practical in terms of maintenance and accessibility—and saves space as well. The combination of the iNSPEC 50 from iTECH Engineering AG with VisionPro from Cognex offers businesses greater reliability in ensuring top quality and short delivery periods, thus helping to lower production costs—a must in difficult economic times.