Papers by Author: Jing Chun Feng

Abstract: In order to exploit the advantages of five-axis flank milling method for space free surface machining to the full, a definition of non-equidistant dual-NURBS tool path is presented first. On this basis, the constraint of velocity of points on the tool axis and the constraint of scanning area of the tool axis are deduced. Considering both of these constraints, an adaptive feed five-axis dual-NURBS interpolation algorithm is proposed. The simulation results show that the feedrate with the proposed algorithm satisfies both of the constraints and the machining time is reduced by 38.3% in comparison with the constant feed interpolator algorithm.

Abstract: NURBS interpolation has many advantages over the traditional linear or circular interpolation in high-speed machining. The existing work in this regard focuses on adaptive feed interpolation considering the chord error constraints and tangent acceleration limits. However, regardless of the dynamic characteristics of individual axis, performance will inevitably suffer when the system is called upon to execute a complex trajectory beyond the range of its capabilities. The intent of the present work is to provide an optimal feed interpolation method respecting both the chord error constraint and the drive constraint of each axis. A look-ahead scheme is applied with a moving window to augment the calculation efficiency for real-time application. Simulations are performed to verify the resulting feedrate, acc/dec profiles and the real-time performance of the proposed interpolator.

Abstract: Self-affine and stochastic affine transforms of R2 Iterated Function System (IFS) are investigated in this paper for manufacturing non-continuous objects in nature that exhibit fractal nature. A method for modeling and fabricating fractal bio-shapes using machining is presented. Tool path planning algorithm for numerical control machining is presented for the geometries generated by our fractal generation function. The tool path planning algorithm is implemented on a CNC machine, through executing limited number of iteration. This paper describes part of our ongoing research that attempts to break through the limitation of current CAD/CAM and CNC systems that are oriented to Euclidean geometry objects.

Abstract: This paper presents a reasonable method for generating the tool-path of free-form surface polishing using the fractal curves. Free-form surface polishing processes as a finishing process are used to reduce the roughness of surfaces and smooth the surface form by eliminating the surface waviness left by tool marks, EDM spark erosion and so on. In the interest of realizing this aim without introducing undesirable surface waviness and time efficiency, a tool-path should provide even coverage of free-form surface during polishing. A fractal curve is suitable to cover the free-form surface uniformly at any complexity due to its plane-filling and self-similar characteristics. A method of generating the fractal path for free-form surface polishing is presented, and also an automatic polishing system is installed to confirm the path planning method’s validity.

Abstract: To overcome the acceleration discontinuity and feed fluctuation of the conventional five-axis grinding interpolator, a jerk-limited acceleration is utilized and two aspects of constraints is taken into account: (1) the machining dynamics, including the constraints of power, velocity, acceleration and jerk represented by upper bounds for each axis (2) the contour constraints of linear segments, including the linear distance of the segment and sharp corner at the segment junctions. With the analysis of these constrains, the optimal feed for each segment and the joint feed at the segment junctions is derived. The corresponding adjusted interpolation algorithm with jerk-limited acceleration is presented such that a smooth motion during the machining can be maintained. The presented algorithm is demonstrated by the simulation result.

Abstract: To alleviate the feed fluctuation and maintain a smooth feed in five-axis machining, this paper takes the following two constraints into account: (1) the machining dynamics, including the constraints of power, velocity and acceleration represented by upper bounds for each axis (2) the contour constraints of the tool path, including the linear distance of the segment and sharp corner at the segment junctions. With the analysis of these constraints, the optimal feed is derived and the corresponding adjusted interpolation algorithm is presented such that a smooth motion during the machining can be obtained. The presented algorithm is demonstrated by the simulation result.