The Research Of Trajectory Control Of Laser Heat Treatment

Compared with the common methods of quenching, laser heat treatment has moreadvantages that the deformation of heat treatment is small, the machining accuracy ishigh, the process period is short, flexibility of processing is good, and it is energysaving as well as environment protecting. However, the existing laser machiningnumerical control (CNC) system can only work through the simple workpieces withthe contour of straight line, circular arc or specific curve. But it can not work throughthe workpieces with the contour of any curve.Through the research and analysis on the laser heat treatment craft of theworkpieces surface, it is knew that to get a good effect of heat treatment of workpieces,hardened layer need to form on the workpieces surface evenly, and the key factor ofgetting homogeneous hardened layer is ensuring that heating effect must be equal allthe time in the process of laser heat treatment. Aimed at the workpieces contour of anycurve, analyzing the technical parameters of heating effects in the process of laser heattreatment, there are three fundamental conditions to make that heating effect is equalall the time come true. First, the distance from the center of laser focusing mirror to thesurface of workpieces remains same; Second, the laser beam always makes itsincidence along the normal direction of the workpieces contour curve; Third, thescanning speed of the tangent that laser spot relative to on the workpieces surface mustbe equal.Based on the above theory, drawing the robotics technology， the paper putsforward the control algorithm based on the three-link mechanical arm. Supposing thatthe laser beam is a whirling arm with the constant length, the control can be simplifiedinto the operation of three-link of mechanical arm. During calculating the sideequidistant curve line, people can make the center of laser focusing mirror move along this equidistant line, and also make the tangent of laser beam perpendicular with thetangent direction of side curve. During the interpolation, people can calculate thereal-time joint angle, and establish the three-line Jacobian matrix, and then obtain thecorner speed. Using the matrix laboratory(MATLAB) programming language, theprogrammatic algorithm comes true. The feasibility and correctness of the algorithm issimulated and verified. The research of this paper solves a technological problem thatdo the laser heat treatment on the workpieces side surface at the three-axis linkagelaser machine, and fills in the blank of the field of any contour curve for the presentlaser heat treatment technology, and establishes the foundation for the application oflaser heat treatment technology in the future.