Three degrees of freedom (DOF) parallel manipulator is used in the applications such as base for various machining operations, drilling inclined holes, airplane and automobile simulators, walking machines, pointing devices, contour milling and machining etc. The 3 DOF parallel manipulator consists of a fixed platform and a movable platform, which are connected by means of three identical links. Pin joints are used to connect the one end of the link and the lead screw pair. This 3 DOF 1R2T parallel manipulator is having one orientation freedom and two translational freedom, which is actuated by means of screw pair, which in turn operated by a stepper motor. The inverse kinematics and velocity equations of this mechanism have been derived mathematically. Based on this inverse kinematics and velocity equations singularity analysis is completed. Two kinds of singularities are compared with ADAMS simulation results and a prototype of the manipulator is developed for further study.
Our project work done for minimizing the welding defects that occur during MIG welding at brake unit in Brakes India Ltd. Welding is the process of joining two similar or dissimilar metals permanently, where MIG welding uses inert gas for shielding and consumable metal for joining two metals. In Brake unit, the welding is performed for joining the web with the rim to form brake shoe. This welding should be very strong so as to resist the distortion due to shear force under dynamic condition. To eradicate frequent occurrences of defects such as blow hole, pin blow hole and start weld. Some of the TQM tools such as cause and effect diagram, Pareto chart, 4 M Methodology and why-why analysis are used to identify the root cause. Hence remedial action taken such as liner cleaning, nozzle cleaning, stopper at the machine bed and tensionner at the feeding unit, helps in reducing the rework rate from 5% to 3%.
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