In machine dynamics the modal analysis of tool holder-spindle assembly is carried out to verify the reasonability of spindle speed, recognize the impaction of vibration modes on machining accuracy and optimize the design of spindle. This paper presents modeling and modal analysis of tool holder-spindle assembly utilizing FEA. Bearing supports is simulated by four uniformly distributed translational spring-damper elements and the radial stiffness of bearings is calculated based on Hertz contact theory. The connection at the tool holder-spindle interface is assumed to be the rigid-connection. This study also proposes two numerical methods in the finite element analysis software ANSYS to simulate the rigid-connection. Consequently, the present modeling and analysis approach by use of FEA is feasible for analyzing tool holder-spindle assembly dynamics.
A real-time and high precision ultrasonic ranging method is proposed here. Ultrasonic ranging system based on MCU was established, which is composed of MCU, ultrasonic sending and receiving circuit, temperature compensate circuit, alarm, key and display circuit. Counting pulse method was used to measure the ultrasonic transmission time, and then the distance is calculated. In order to improve the ranging accuracy, temperature compensation was used in this system. Preliminary experiment showed that the system meet the requirements. This system has advantages such as low price, small volume, reliable operation, high accuracy, and can be employed in car backing, obstacle avoiding of robots, industrial logging, reservoir level measuring etc.
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