Performance Research On Heavy-Duty Forging Manipulator System

The manufacturing of heavy forgings is the foundation of heavy equipment industry,and the automation of forging process is the necessary condition for the production ofhigh-productivity, high-quality and low-cost heavy forgings. This work focuses on theneed of automation in heavy forging production, and discussed some key technologies onthe modeling and performance analysis of heavy-duty forging manipulator system, whichcan be integrated with forging press to realize programmed open-die forging process.These key technologies include kinematic modeling and analysis of forging manipulator,dynamic tip-over stability of mobile manipulator, the overall model of the coordinatedforging system that includes press, manipulator and the forging process, the compoundstiffness model for the compliant control of manipulator, pass schedule of programmedopen-die forging process, and the software realization of virtual open-die forging plants.This dissertation’s main work can be concluded as:1) A new-type serial-parallel forging manipulator is presented, the closed formdirect and inverse kinematic solutions are derived, and the analytic algorithm for thecomputation of Jacobian matrix is also presented. Based on which the kinematicperformance and the load capacity are analyzed. All those lead to the establishment of themathematic model of the forging manipulator.2) A new tip-over stability measure for mobile manipulators is proposed, whichhelps to improve the operational safety of the forging manipulator. This measure has aconcrete physical meaning, considering all static and dynamic factors under different working state of mobile manipulators.3) The compliance velocity of the manipulator gripper during forging is derived onthe basis of Spread Coefficient theory of open-die forging process, based on which theoverall coordinated model of the integrated forging manipulator system is established.This model can be used for trajectory plan or kinematic simulation of virtual forgingsystem.4) The mechanical interaction of the deformed workpiece and the compliantcontrolled manipulator is built. Firstly the elastic and plastic deformation model of theshaft-shaped workpieces are investigated and the elastic stiffness matrix of thenon-deformation portion of the workpiece is derived; Then the conservativeoperational-space stiffness matrix of the manipulator is computed by using the method ofConservative Congruence Transformation (CCT); The compound stiffness model of thewhole system is established base the elastic stiffness matrix and the conservativeoperational-space stiffness matrix.5) The simulation algorithm for square bar drawing process between simple dies isproposed based on Spread Coefficient theory and geometric transformation. The real-timesimulation algorithm of programmed forging process is then formed.6) The software architecture of the virtual forging system is proposed, and thedesign and analysis processes of the software are conducted. Some key technologies forthe software development, such as automatic simulation of multi-step open-die forgingprocess and the visualization of the simulated complex forging process in virtual realityenvironment, are investigated.This work provides a relatively complete theoretic base for the analysis and design ofheavy-duty forging manipulators, programmed forging process conducted by coordinatedpress and manipulators, and the realization of virtual forging system.