Development Of A CAM System For Automated Equipment For Composite Dressing Of Superabrasive Grinding Wheels

Superabrasives(diamond and cubic boron nitride)forming grinding wheels can complete all machining processes in a single grinding process when grinding workpieces,which can reduce the processing cost in the production process while ensuring the machining accuracy and efficiency,and are widely used in the processing and manufacturing of high-precision and complex surfaces.Due to the high wear resistance of superabrasives,it is extremely difficult to dress the surface of superhard abrasive grinding wheel to produce high precision and complex profiles.At present,superhard abrasive grinding wheel is usually dressed by mechanical method,but the efficiency is not high.The efficiency of EDM dressing is better than the mechanical method,but it is difficult to dress non-conductive material wheels and coarse grained metal bonded grinding wheel.Compared with a single dressing method,the multiprocess composite dressing method has obvious advantages.Among them,the lasermechanical combined dressing process has high dressing efficiency,adaptability and precision,and there are many process studies verifying its advancement,but it has not yet formed an automated dressing system to meet the industrialization requirements.In this paper,based on the combined laser-mechanical grinding wheel dressing process,the research of automatic dressing CAM system is carried out.(1)The CAM system design is based on the self-developed laser-mechanical combined dressing equipment.The composition of superhard abrasive grinding wheels and their characteristics,the structural layout and detailed performance of each CNC axis of the composite dressing machine tool,as well as the corresponding CNC system categories and models,the principles of laser dressing and mechanical dressing are analyzed,on which the dressing strategy of laser rough dressing,semi-finishing dressing,and then mechanical finishing is formulated,the composite processing trajectory is planned,and the processing obstacle avoidance requirements are determined according to the planar three-axis structure of the machine tool,in order to meet the increasingly complex contour dressing requirements of forming grinding wheel.(2)The related dressing algorithm is designed.The calculation principle of the trajectory biasing algorithm is derived as the basis,and the relevant solutions are designed for the various trajectory incoherence phenomena that occur during the biasing process.In the laser dressing trajectory generation strategy,the laser dressing process is divided into two steps which are laser roughing and semi-finishing,and the single-slot trajectory filling algorithm and multi-slot trajectory dressing method are proposed,while the laser dressing trajectory is optimized for the relationship between laser dressing wheel incidence angle and removal material to improve the dressing precision.In the mechanical finishing trajectory generation strategy,the generation principle of three-axis trajectory is analyzed in detail,the computational volume of constraint solving is significantly reduced by the enclosing frame method,and the intersection calculation is performed using the vector method,which optimizes the program logic.The error model of B-axis angle affecting contour trajectory under fixed tool setting error is established,and the solution strategy of B-axis angle is determined.(3)Determine the program framework and functional modules,and design the following modules: parameter input module for processing drawing and tool information,toolpath calculation module for generating toolpath trajectory by trajectory offset and collision detection,simulation module for simulating toolpath trajectory and displaying real-time tool attitude to visualize machining process,and program generation module for converting toolpath trajectory into machining code by adapting to the existing tool setting method and machine structure characteristics.(4)The dressing experiment was carried out with coarse-grained(150#)diamond bronze bonded grinding wheel as the dressing object.The results show that the system can generate laser roughing,semi-finishing,and mechanical finishing machining programs without collision and overcutting of the machine tool,which greatly improves the efficiency of automatic compound dressing code programming.The surface shape and precision of the dressed grinding wheel were inspected,and the contour error was within 9.1 μm and the circular runout was 6.1 μm.