| The quality and efficiency of gear machining in the machinery industry have largely reflects the level of a country. With the development of science and technology and the level of equipment have improving; the high requirements for gear transmission products. Spiral bevel gear is the foundation of mechanical transmission components, because of its complex shape, more technical issues and difficult to manufacture, has been deeply valued by the industry. The current gear CNC system is mostly foreign CNC system, such as Germany SIEMENS, Japan’s FANUC and PHILIPS Company’s 3460 CNC system, or secondary development in the general CNC systems (such as Siemens 840D) just make the basis of relevant gear machining technology embedded into the CNC system to achieve gear machining function, in that way its will lack of specificity, and scalability is not strong. In order to improve gear machining precision and drive performance should start the source machine tools-CNC system, to develop specialized gear CNC system without relying on foreign CNC system. Therefore, this paper presents an embedded CNC spiral bevel gear system about the software and hardware design and development, in order to further improve precision of spiral bevel gear machining, conducted a study of the following:1. By comparative analysis the principles and tools of spiral bevel gear machining that traditional crandle machining and CNC machining. Analysis contraction arc spiral bevel gear of the big gear generated machining, format machining, and modified roll machining and tilt machining for the pinion, four gear cutting processing methods. Application space coordinate transformation, were deduced the CNC machining models for that four machining methods.2. To study the errors of tool effects on the tooth surface accuracy, from the profile angle and radius of the cutter tool. Derive quantitative mapping between tool radius deviation and work-piece tooth profile error, and quantitative mapping of the relational model by tool profile angle deviation affect the work-piece tooth profile error, without considering the accuracy of the machine movement. Then respectly simulated the deviation of tool radius and tool profile angle impact error of tooth surface. In order to reduce the deviation cutter caused tooth surface machining accuracy decreases. And design tool compensation amount in the development of spiral bevel gear CNC system. And use a virtual machining simulation, to verify the mathematical model of tool error compensation, and the result show that can effectively improve the spiral bevel gear CNC machining surface accuracy.3. Arcodding to the deduced machining models of spiral bevel gear generated machining, modified roll machining and tilt machining have ferry variability on multi-axis machining different requirements, were constructed respectively corresponding electronic gear box structure model. Considering that gain matching can bring low tracking precission to a certain extent, combining the characteristics of the movement track for the spiral bevel gear cutting tool during machining, the cross-coupling control model been used between the linkage feed axis, establishing its cross-coupling compensation model and carried out experiments to verify the effectiveness of the cross-coupled control model.4. In order to improve the machining accuracy of CNC spiral bevel gear machine tools, on the basis of analyzing the characteristics of spiral bevel gear machine CNC motion to establish its motion model and deduce the speed relationship between the tool and the workpiece. Then based on the theory of multi-body system describe topology for spiral bevel gear CNC machine tools. Each of the base coordinate system and the local coordinate system of spiral bevel gear CNC machine tools were set, combined with the machine kinematics error deduced the error model with homogeneous transformation matrix. For the error compensation movement and error model (position and orientation error) have the coupling relationship, based on the assumptions of little error compensation and principle of derivative motion transformation, and combined with the relationships of electronic gearbox for the spiral bevel gear CNC machining, to decoupling geometric error compensation movement, next, to obtain the each error compensation amount about the position and direction movement which impact CNC machining accuracy.5. The overall architecture of CNC software and spiral bevel gear NC automatic programming system were designed based on the modular throught, on the numerical control system for multi-CPU embedded hardware platform, on this system based on this architecture, includes input modules, output modules, automatic programming module, system parameter setting module, communication module and so on. In order to achieve the CNC spiral bevel gear into processing, the internal information flow of CNC software was analysed detailedly, and the Electronic gearbox was embedded in the gear machining CNC system seamlessly. Strategy of acceleration/deceleration was considered when the Electronic gearbox synchronization start or cancellation is specified, in order to avoid the mutation of the slave axis speed during the Electronic gearbox suddenly turned on or off. By comparing the calculated data program running experimental data and theoretical analysis, shows the correctness of the electronic gear box software execution, and also institude that the CNC system of spiral belvel gear can machining.6. Comparison of experimental data and calculation by the program running for the independent development of embedded systems spiral bevel gear machining, to verify the correctness of the software execution. Then, to experiments the motion control of the spiral bevel gear CNC system contain electronic gear control model on the six-axis machining experiment platform, by generating method and modified roll method, and thought the quantitatively analyzed and compared the experimental results, certify the control structure and implementation of the proposed spiral bevel gear NC machining with good controllability. |
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