Study On Machining Mechanism And Its Key Technologies Of High-layer CNC Cutting Machine

High-layer CNC machine has advantages in high machining efficiency, high utilization of raw materials, non-damage for cutting objects and lower pollution, thus it plays a more and more important role in machining sheet non-metallic materials such as fabric and leather. Aiming at solving machining problems, namely, thick fabric/leather in clipping areas, high feed speed, complex cutting paths, and feeding fabric/leather continuously during cutting, machining theory and some key technologies are deeply researched. It consists of speed planning method with multi-factor correlated, three-axis interpolation algorithm with real-time dynamic tangent situation, interpolation algorithm and speed planning for machining under condition of clipping and fabric/leather moving at the same time, and machine tool deformation problem under dynamic load and its machining error analysis. Research of machining mechanism and key technologies and its application for high-layer CNC machine, it provides great theory assistance for innovative technique schemes in stableness of equipment operation, high intelligence of cutting planning, and conversation of energy saving.1. Real-time dynamic tangent interpolation algorithm with three-axis movementThe interpolation process with three-axis movement is contained in the high-layer CNC cutting room machining procedure, the feeding movement along with X and Y axis, and auxiliary feeding movement along with Z axis. We propose the interpolation algorithm with three-axis movement in same steps along with Z axis based on the cutting curve types, line or arc. For the NURBUS curve, high curve interpolation algorithm with three-axis movement in same step and same compensation value is proposed, with constraints of maximum height of arc segment and maximum of normal acceleration. We take the curve with large curvature and cutting contour with sharp cusp as research objects, and propose the interpolation strategy, that is the curve replaces the line, the curve replaces the curve. With this method, it can reduce the time of putting knife and enhance machining efficiency. The simulation results show that three-axis interpolation algorithm for real-time dynamic tangent can achieve the machining expectation with efficient controlling method and satisfactory precision.2. Research of speed and acceleration planning for cutting machineBased on the three correlated factors, namely, shear strength, cutting thickness, and cutting curve curvature, we propose the speed and acceleration planning method. Construct speed and acceleration planning model for linear cutting path based on material characteristics and cutting amount. On the basis of linear model, we build speed and acceleration planning model for arc path with permanent curve curvature, and then deduce the model for oval path, parabola path and hyperbola path with variable curve curvature. And based on the above method, we propose the speed and acceleration planning for NURBUS curve. We make simulations for the speed and acceleration planning model, the experimental results show that it can improve processing efficiency and keep stable operations, and it proves the effectiveness of the proposed model.3. Research of real-time dynamic interpolation algorithm and speed planning under condition of clipping and fabric/leather movingIn order to improve machining efficiency and realize continuously feeding fabric/leather process, suitable interpolation algorithm and speed planning method are proposed. After analyzing movement rule of feeding structure, we establish the interpolation model with four-axis movements, which are transverse and longitudinal feed movement, real-time dynamic tangent movement, and fabric/leather feeding movement. And then we build the speed control strategy and planning algorithm under the condition of clipping and fabric/leather moving. We take simulation experiments to test the feasibility of the interpolation algorithm and speed planning method. The proposed method provides important theory support for enhancing machining efficiency and product technology upgrade.4. Deformation of the cutting tool and error analysis under dynamic loadTake an analysis of machine tool force and torque in machining process with low-order curve and high-order curve paths, and deduce the elastic composite deformation model under dynamic load based on integration method. We propose a calculation method for calculating curve cutting error of machine tool caused by the composite deformation under dynamic load. In high-frequency vibration motion condition, we make analysis of rules of variable load for cutting tool with linear cutting, conic cutting and high-order curve situation, and establish elasticity model and error calculating method, and propose the compensation method. Through the dynamic monitor for machining process, it testifies the reasonableness and efficiency of the analysis for deformation error and compensation method.Theory analyses and experiments indicate that the research achievement of machining mechanism and its key technologies for high-layer CNC cutting room provides great value in theory research and engineering application for processing efficiency and intelligent control in machining process.