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Design And Analysis Of The Large-scale Forging Manipulator Based On Parallel Mechanism Theory

Posted on:2013-01-03Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y D XuFull Text:PDF
GTID:1221330392954870Subject:Mechanical and electrical engineering
Abstract/Summary:PDF Full Text Request
Forging manipulator is one of the important equipments for the modern forgingsystem. By using the forging manipulator, production efficiency and quality of the heavyforged piece can be greatly improved. However, design and analysis of the large-scaleforging manipulator is still almost blank home, so design and analysis of the large-scaleforging manipulator will be carried out systematically based on parallel mechanism theoryin this paper. The main research contents are as follows:Type synthesis of the forging manipulator is studied systematically by using theconstraint-synthesis method based on screw theory, many new configurations of parallelmechanism and hybrid serial-parallel mechanism for the forging manipulator are obtained.Two simple methods for distinguishing the mobility’s instantaneity of the overconstrainedparallel mechanism are put forward, and the mobility’s instantaneity of theoverconstrained parallel mechanisms for the forging manipulator configurated above isdistinguished by using the proposed methods.Based on three motion characteristics, which are decoupling, installation position ofthe lateral buffering cylinder and clamping ability, respectively, a typical mechanism ofDDS forging manipulator, a typical mechanism of SMS forging manipulator, and four newmechanisms of forging manipulator are compared. Forward positon and static analysis ofthe main motion mechanism of five mechanisms among them are conducted, thencomparative analysis on comprehensive force performance of these five mechanisms iscarried out, and several regular features of force performance of the forging manipulatorare also discovered.Two novel methods for establishing deformation compatibility equations of theoverconstrained parallel mechanism are proposed, and the general analytical expression ofthe actuated force/moment solution to the redundantly actuated parallel manipulators isderived in the condition that system elastic deformation is taken into account. Besides, it isproved that no internal forces exist within the pseudo-inverse solution to the actuated force/moment of the redundantly actuated parallel manipulators. And then, theoreticalanalysis results are applied to solving the actuated forces of the redundantly actuatedforging manipulator2SPS+R. The linearly dependant constraint wrenches imposed on themoving platform of the passive overconstrained parallel mechanism are defined asoverconstraint wrenches, and they are transformed into equivalent linearly independantconstraint wrenches. Then considering the link’s bending, tensile and torsionaldeformation, Stiffness matrix of the branch’s overconstraint wrenches is deduced, a morecomplete and universal method for force analysis of the passive overconstrained parallelmechanism is built up, and force analysis of a passive overconstrained suspensionmechanism4-SS of forging manipulator is performed by using this method.Considering the gripper carrier’s all forging operation action, two new parallel linkmechanisms of forging manipulator are taken as examples, the degree of freedom of thewhole mechanism of forging manipulator is calculated by using the modifiedGrübler-Kutzbach criterion. Taking minimum gravitational potential energy of themechanism as the constraint condition, optimization analysis of the mechanism isperformed, and the actual motion law is obtained. Kinematic analysis of the wholemechanism of forging manipulator is carried out, and the mechanism is simulated byAdams software to testify the correctness of the theoretical analysis results.A modified scaling factor method for force capabilities analysis of the planar parallelmanipulators is presented, by which the solution of the largest force and the largestmoment can be derived. For this modified method, the process is computationally smalland the results obtained are more exact. The largest weight of the forged piece and thelargest moment generated by the eccentricity of the forged piece that a new mechanism offorging manipulator is analyzed by using this modified scaling factor method.A new approach for establishing simulation model of the parallel mechanism basedon Adams software is proposed.This modeling method is simple, fast and versatile, whichcan realize kinematic simulation and dimensional optimization analysis of the parallelmechanism quickly. And then, parametric model of the main motion mechanism of a newforging manipulator is established by using the new approach, dimensional optimization ofthe mechanism is carried out. Experimental model with ratio1/20of a new forging manipulator is developed, andexperimental study on completing various forging operation action and force performancetesting is performed. The experimental results show that the new forging manipulator canachieve all the forging operation action as the configuration theory analyzed, and verifythe conclusion that the lifting cylinder’s driving force of paralle link mechanism of forgingmanipulator is independent of the eccentricity of the forged piece.
Keywords/Search Tags:Forging manipulator, Parallel Mechanism, Type Synthesis, overconstrained, Instantaneity of Mobility, Redundantly Actuated, Force capabilities, Simulation model
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