Nuts are common fasteners utilized in automotive and construction industries to assemble components together at ease. With the increase in production of automatic fastener couplers and the augmenting need for automatic mechanical assembly of components without human intervention, it is crucial that the fasteners being utilized in such machines are perfect. Hence the assessment of internal threads in nuts prior to usage becomes imperative and for which an automated batch mechanism has neither been designed nor employed in Indian industries. There has occurred one drastic incident in the defense field in 1960. Around 1200 M-60 tanks had to be removed off the front line for 2 months as defective bolts were to be replaced in the gun mountings to avoid a national security risk scenario. An analysis from the Accidents and Defect databases of the UK Vehicle Inspectorate also shows that up to August 1994, a total of 323 cases of wheel loss had been identified since 1982 out of which 72% were due to maintenance failure. Therefore, this project aims at eliminating such risks involved in utilization of defective nuts by the use of vision based system and high speed mechanical sorting of defective ones. An automatic batch process is designed to displace the nuts on a conveyor belt and sort them based on results obtained by processing images of internal threads captured using a high resolution camera. Industrial standards require that the processing and sorting are done at a very high speed and hence this model incorporates NI CRIO to perform the motion control, processing and sorting. The conveyor belt is run by a 12V DC motor and pre-programmed control signals from the CRIO. Edge detection is performed on the obtained images using the NI Vision Development Module in order to analyze the continuity of the female threads. The fasteners found to be defective are then segregated by mechanical flappers placed at one end of the conveyor belt which is again controlled by the CRIO. This model would break through the conventional manual inspections, improve quality standards in the Indian industries, and it will drastically reduce dependence on foreign suppliers. It will serve as a compact and cost-effective system with easy user-interface to benefit the SME and other Industries in India. Hence, it will drastically reduce the by Indian industries.
