Study On Key Technology Of A New Large Forging Dimension Measurement System

Large forging is the key part of important equipments. The demand of large forging is gradually growing with the development of China's power, shipbuilding, oil and chemical industry. Large forging usually is processed with Open Die Forging Method. Advanced online dimension measurement technology plays an important role in improving the performance of Open Die Forging System. The paper combines the urgent need of high-quality large forging by state's major industries and research status of measurement technique. With the support of National Key Basic Research and Development Scheme, a comprehensive and exploratory research on large forging dimension measurement system is developed so that it can provide support for improving the performance of forging manipulator. The paper's study has several points as follows:A new large forging dimension measurement method is presented based on using pulsed laser ranging sensor with spherical two-DOF parallel mechanism. Its basic theory is that laser sensor complete quick and stable scan drived by spherical two-DOF parallel mechanism which has the characteristics of high dexterity and precision. The dimension of large foring can be determined with these datas gotten by scanning. The measurement system can measure the rotated angles of mechanism and the distance information of measured point. The coordinates of measured points in measurement equipment coordinate system can be calculated by coordinate transformation based on spherical parallel mechanism. Spherical conformal theory is applied to the workspace analysis of spherical two-DOF parallel mechanism. A set of points on plane are used for express the workespace of spherical two-DOF parallel mechanism. The workspace size can be researched by analyzing the projection circle radius size of locomotory points. It provides theoretical basis for balancing the workspace size of measurement equipment. Jacobian Matrix of measurement equipment is calculated. According to the Jacobian matrix, it analyses the singular configuration and reviews the reliability of the system. Also it analyses the decoupling and istropy of the mechanism so that it can reviews the controllability of the system.The working method of mechanical system is decided by the analysis of working performance. The control system has been built by choosing precise brushless DC motor and modularized motor controller. The control method of Brushless DC motor is researched and the PID parameters optimization of current loop, velocity loop and position loop are completed.The process of datas acquisition is designed. The serial data acquisition rapidity is improved and the user interface response capability is retained by the application of Windows multimedia timer. Real-time display of 3D point clouds acquired from measured objects is completed.It makes the acquisition process more visualized and lays a solid foundation for on-line size measurement.Some experiments are arranged based on developed measurement system. The results of these experiments indicate that the measurement system can achieve definite accuracy. It has the guiding significance for further research on online automatic dimension measurement of Large Forging.The research of this dissertation lays the foundation for successful development of the new large forging dimension measurement system.