Inspection of head gasket in passenger car engines
The structure of modern diesel engines is very complex. Each engine consists of numerous parts that allow the combustion of the fuel mix when working together. It is self-evident that the engine parts directly affect the performance and reliability of the engine. One of the biggest challenges which designers face is to ensure a perfect sealing of each component. This applies in particular to such a crucial engine component as is the engine head gasket. The choice of the correct gasket thickness should not be underestimated in the engine production, as this component provides sealing between the engine head and the engine block, and it is supplied with oil and cooling liquid through the designated channels. And as the gasket must work in a wide range of temperatures and is exposed to various loads when the engine is running, the quality of the gasket is a key issue.
The Polish integrator company PSA Zapis Hardware constructed a workstation for a leading European manufacturer of diesel engines for checking the correct installation of gaskets. To ensure the highest level of quality and certainty that the sealing will perform its function, the manufacturers carry out strict checks and intensive testing already within the designing process. Nevertheless, it is not enough to reach high quality just with human sense which is often unreliable and inaccurate. Therefore the optimum solution turned out to be an intelligent machine vision system - the most powerful tool used in quality control.
For this installation, Zapis decided to use the In-Sight 1100 vision system and the VisionView 700 control panel – both devices developed by Cognex, the world leader in the machine vision and industrial ID industries - which continuously monitor the visual application. Thanks to many years of experience gained in designing and developing machine vision systems, the operators at the end customer site have quickly learned how the application works in practice.
Its durability and accuracy are the camera’s main advantages. Thanks to the housing made of aluminium and stainless steel, the system is vibration-resistant. Despite the In-Sight Micro’s small dimensions (30 mm × 30 mm × 60 mm), it offers a wide range of options for use, and it significantly increases the efficiency of monitoring the correct installation of the gaskets. Depending on the engine type that is manufactured, the appropriate program is uploaded to the vision system. It then evaluates if the gasket type is correct and if its thickness is adequate. After re-measuring, the result is entered into the Moby system. The user interface displays on the VisionView 700 panel, enabling operators to add new gasket types very easily. The system is connected to the PLC (S-7) via I/O.
Speed is another asset: The In-Sight Micro can acquire up to 60 images per second in a standard 640 × 480 pixel resolution, and allows displaying the latest images of the inspected detail, in this case the engine head gasket. It can check about 2400 engines a day, with a reliability of 100% - this impressive result cannot be reached with any other commonly-used quality testing method.
Author: Petr Pohorský, free specialised journalist