Automotive brake shoe sorting system

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Automotive brake shoe sorting system

Baldur, R. / Horth, R.

The first step in the refurbishing of automotive brake shoes is sorting. The parts that arrive from various shops are dirty, rusty, often damaged and are randomly mixed. Sorting is performed manually by trained personnel who recognize the model number, inspect the shoes and stack them according to their designation. A large plant may reline several thousand shoes per shift and costly errors often occur due to operator fatigue or lack of training. The installation described in this paper uses machine vision at the heart of the system. The used brake shoes are loaded onto a conveyor which transports them through a width measuring device and a machine vision contour detection station. The back-lighted parts are analyzed by a special purpose software that extracts only the significant characteristics from the image. The latter, combined with the previously obtained width leads to the determination of the model number. There are several hundred models. Many of them differ in minute details only, on the other hand, indentical models vary over a wide range due to manufacturing tolerances often related to the source of the original parts. Furthermore, shoes from outdated cars are modified to fit the vehicles in current use. The recognition system handles these difficulties. It is virtually error-free and performs the operation at a rate of about 4000 units per hour. The conveyor system is equipped with a series of gates, one for each brake shoe model. The recognition system retains in its memory the position of all shoes on the conveyor and activates the appropriate gate when each part reaches its designated position. Damaged or outdated parts are rejected.