Research On Curve Fitting And Track Optimization Of NC Cutting System And Its Application

Cutting machine is the intelligent CNC(Computer numerical control) processing equipment which integrated the digital control technology and precision machinery manufacturing, whose appearance greatly lighten the problem of low productivity on the craft and mold manufacture. However, the resource of the traditional cutting machine is limited, as well as the processing of graphics files process is quite fussy, so neither the accuracy nor the efficiency are difficult to achieve.This paper is based on the whole process of CNC cutting machine dealing with graphics, which mainly focus on how to design control system, graphics identify, and process tracking. The following results have been reached:Firstly, the project file that can be identified by CNC cutting machine is created. Vector graphics, to be processed, need to be expressed by line or arc. So a series of data points are sampled in the B-spline curve by the method of curve fitting, then arc and line fitting is conducted. In order to improve the cutting accuracy, fuzzy reasoning method is used to determine the state of curve fitting and determines the membership function based on lines and arcs.Secondly, the process path is optimized. Reducing free travel is an effective way to achieve the optimal path, which related to two factors about the processing sequence of graphical contours and starting points of every contour. In the practice, the cutting path and drawing path are solved respectively. When cutting path is optimized, the graphical processing path problem is regarded as the traveling salesman problem after taking into account the contain problem of inner and outer layers. The processing sequence of graphical contours is found out by the way of traversal. And the nearest neighbor algorithm determines a starting point from each contour. So the processing path is also determined. When drawing path is optimized, the nearest neighbor algorithm is used to deal with closed and opened graphical contours.Thirdly, the control system is based on LPC2138 microcontroller andμC/OS-II real-time operating system platform which carries on various tasks suitably. Some external control modules, such as power control systems, motion control systems and communications systems, construct the control system hardware design. Software adopts a multi-task system to write code, so the CNC cutting machine can cut and draw graphics stably and efficiently. And LCD screen displayer provides users with a good interactive mode of operation. The cutting of NC graphics can be realized.To maximize the processing efficiency of cutting plotter, there are still a lot of shortcomings on the proposing of this article, also there are many topics awaiting us to carry out research in further.