Research On The Related Technology Of Variable Pressure Belt Grinding On Free-form Surface

With the rapid development of technology, the parts with free-form surface shape are used increasingly widespread in the automotive, aircraft and ships, and they all have higher requirements on both the quality and efficiency of grinding process on these parts. Aiming the characteristics of belt grinding free-form surface, This paper presents a method that changing the grinding force at different curvature of the surface when grinding free-form surface. The main of the method is establishing the mathematical model of material removal in the processed workpiece with the curvature of each point on the surface, and carrying out quantitative grinding through precising control of grinding force with the control system of belt grinding mechanism.Study of this subject is mainly reflected in the following aspects:(1) Combining with data points and weighting factors of free-form surface, and surface boundary conditions given, using the surface inverse method of non-uniform rational B-spline to establish the model of surfaces, then calculating the value of normal curvature at any point on the surface with the matrix expression of surfaces are derived.(2) Assuming that the contact between the contact wheel and the workpiece meets Hertz contact theory, then establishing the model of material removal at the point on grinding locus on the basis of the normal curvature in the point of surface obtained, and revising the Preston constant in the mode. Calculating the grinding force of control points with the model modified, and simulating the result of the trend angle θ and the grinding force or grinding depth.(3) Designing a set of belt grinding mechanism with adjustable grinding force, and choosing the important parts of the mechanism reasonably. Finally, it has completed the design and assembly of the parts, as well as the interference checking of the mechanism.(4) Establishing the grinding force control system, adjusting the pressure value of low friction cylinder through an electric proportional valve to control grinding force indirectly. Designing the pneumatic control circuit and the hardware composition of electronic control section of the control system, and choosing the important parts in the system reasonably.