Research On JDYP52 Type Virtual Axis Polishing Machine Tool

Parallel machine tool is a knowledge-intensive institutions, essentially, it is a combination of modern robotics technology and machine tool structure, its prototype is the Stewart platform.1. Research SignificanceIn order to improve the adaptability of the production environment, meet the fast changing market demands, In recent years, the global machine tool manufacturing industry are actively exploring new multi-function manufacturing equipments and systems,the technical breakthroughs of machine tool structure is the parallel machine tool, which come out among in the mid-90's,also known as virtual axis machine tool or parallel kinematic machine. Parallel machine tool is a knowledge-intensive institutions, essentially, it is a combination of modern robotics technology and machine tool structure,this new machine tool completely break the traditional concept of machine tool structure and abandoned tool-oriented approach of fixed guideway,used the multi-bar parallel mechanisms driven.This new machine tool greatly increased the stiffness of machine tool,improved the quality and precision of processing. In addition, because of Improving feed speed,Thereby enabling high-speed, ultra-high-speed processing is more easily achieved. As a result of this machine with high stiffness, high load-bearing capacity, high speed, high precision and light weight, simple mechanical structure, high degree of standardization, the parallel machine tool have been successfully applied in many fields. It can be said that the virtual-axis NC machine tool is considered the most of revolutionary breakthrough in machine tool design in this century,also on behalf of the direction of machine tool development in 21-Century. As a new development direction of machine tool,parallel machine tool(virtual axis machine tool)have a wide range of applications and potential value In various fields of social life,so that there is great significance and value of researching and developing the parallel machine tool.Due to the complexity of parallel machine tool's agencies,the current understanding of the parallel machine tool is not enough,and lack of thorough research. there are a lot of issues in kinematics,dynamics and work space of parallel machine tool,which have not been resolved.The resolution of these issues will contribute to the study application and promotion of parallel machine tool,also plays a significant role in advancing and promoting new types of machine tool design and research. On the other hand,because of the complex space agencies of parallel machine tool, there is lot of complexity calculation and characteristics in analysis, research and evaluation the model of parallel machine tool,which include kinematic model, the work space model, dynamic model, control model and the model error analysis, etc, so its very important to use computer simulation. it is an important and effective way to use computers'powerful analysis and calculate capabilities in research of parallel machine tool,which can greatly enhance the efficiency and accuracy. moreover,we can evaluate the performance of a certain part of the system and influence between parts in using computer simulation parallel machine tool. More importantly,computer simulation can shorten the product development design cycle,reduce the risk of investment,accelerate the manufacturing products with excellent performance. Therefore,computer simulation is a essential part of the development of parallel machine tool.At present,although there are many institutions have done a great deal of research of the virtual axis machine tool, However, most of then just research simple virtual axis machine tool.there is few report about research of the virtual axis machine tool,which is used to grind free-form surface.therefore,it is very significant to resaerch and design the theory and key technologies of this virtual axis machine tool.2. Theoretical AnalysisStarting with the structure of the 3-HTT parallel mechanism,this article derived direct and inverse kinematics solutions of the mechanism. Because it is easy to analyze the inverse kinematics solution and hard to analyze the direct kinematics solution, and it is necessary to realize the real-time calculation of the inverse solution while controlling the Dynamic Motion Simulator. So this paper, gaved a detailed inverse position solution, and did not make further study on the direct position solutions, only gave a Newton iteration method.Firstly, this paper analyze the degree of freedom of 3-HTT parallel mechanism,the conclusion is that this parallel mechanism just have 3-DOF in direction of X, Y, Z axis,it can't change the attitude angle around the X, Y, Z axis.By using coordinate transformation and geometric computing institutions,can draw the parallel inverse kinematics solutions, based on the inverse kinematics solutions,can draw direct kinematics solutions by Newton iteration method.Then compare the figures of kinematics curve,which is drawed by ADAMS(Fig 1) and MATLAB(Fig 2). work space is one of the most important performance indicators in the design of parallel mechanism of JDYP52 virtual axis machine tool. According to the structure of 3-HTT parallel mechanism, given the factors,which impact of its work space, including: the restrictions of screw's removable length;the restrictions of Hooke hinge's angle;the interference of virtual-axis machine tool in the overall size. By combination of the inverse kinematics solution,the factors and border search method,can draw the figure of procedure(Fig 3). By using MATLAB,can draw the workspace of this 3-HTT parallel mechanism(Fig 4). 3. Three-dimensional design and Prototype SimulationModel the parallel mechanism of JDYP52 virtual axis machine tool by CATIA,which hve been designed with paramete.Model the prototype model of parallel mechanism of JDYP52 virtual axis machine tool by ADAMS.as (Fig 5).Simulate the prototype model,then output the figures of dynamics curve. And then establish the kinetic model of the parallel mechanism by the basic theory of dynamics(Newton-Euler equation),Then compare the figures of dynamics curve,which is drawed by ADAMS(Fig 6) and MATLAB(Fig 7).4. Finite Element Static AnalysisWhen the machine tool is working,in order to determine the parts of JDYP52 virtual axis machine tool can be normal, the key parts of parallel mechanism must be analyze by finite element static analysis softwaref(ANSYS).Analyzing the rotation axis,swing axis,cradle and rocker of Hooke hinge by ANSYS,when the machine tool is working in the case of maximum acceleration.In this design,the parts of Hooke hinge are in accordance with design requirements.5. ConclusionIn this paper,we design the parallel mechanism of JDYP52 virtual axis machine tool base on JDYP51 virtual axis machine tool.Then through kinematics analysis, workspace analysis, dynamic analysis three-dimensional design, prototype simulation and finite element static analysis of this parallel mechanism, determine the design and development of this parallel mechanism is in accordance with the requirements of indicators.