HSM Strategies of CAD/CAM Systems — Part I Tool Path Generation

2010 ◽  
Vol 426-427 ◽  
pp. 520-524 ◽  
Author(s):  
Song Lin Ding ◽  
John Mo ◽  
D. Yang

Owning to the ultra high feed rate and spindle speed, tool path patterns which are less important in conventional metal cutting processes becomes critical in High Speed Machining (HSM). Without an appropriate tool path strategy HSM can not be fully implemented even though the CNC machine has HSM potentials. In practice attentions are usually drawn to advanced hardware components; tool path pattern catering to HSM is often overlooked. This paper introduces the principles of tool path generation for HSM. Essential properties of HSM and its technical requirements on the CAD/CAM system are summarized. The state-of-the-art technologies and practice-oriented tool path generation methodologies are presented.

2010 ◽  
Vol 102-104 ◽  
pp. 544-549 ◽  
Author(s):  
Chun Jiang Zhou ◽  
Hong Chun Chen

The development of surface high-speed machining has put forward higher demands for uniform cutting load and smooth cutting tool path. Most current tool-path planning methods are based on constant scallop height, but they have the disadvantage of path point redundancy during the path discretization process. To overcome the problem, a tool path generation method of equal approximation error in each step for free-form surface is presented based on geodesic principle and curvature judgment. In this method, the NURBS curve is employed to realize smooth transition for adjacent two tool paths in high-speed machining. A certain angle of inclination of flat-end milling cutter during multi-axis machining improves the machining efficiency. Because of the advantage of this machining condition, the cutter location point generation algorithm during the machining condition is given by the method. The method is verified and simulated by C++. Experiment results proved that it can obtain uniform cutting load and continuous smooth cutting tool path during surface high-speed machining by the proposed method.


2010 ◽  
Vol 2010 (0) ◽  
pp. _2P1-G21_1-_2P1-G21_3
Author(s):  
Akira Bekku ◽  
Taiga Nakano ◽  
Naohiko Sugita ◽  
Yoshikazu Nakajima ◽  
Takeharu Kato ◽  
...  

Author(s):  
Peter Jang ◽  
James A. Stori

This paper presents a new offsetting approach for tool path generation in three-axis sculptured surface machining. The approach generates tool paths with scallop, curvature, and force characteristics which make them suitable for high speed machining. An ellipse in the parametric space is used to approximate the intersection between the ball-end mill and the scallop surface for any cutter contact point on the surface. The envelope formed by these swept ellipses of varying dimension and orientation creates a constant scallop curve which is used to generate offset paths. The offset is developed incrementally, utilizing post-processing techniques to eliminate high-curvature regions in the trajectory. The offsetting approach can generate continuous spiraling trajectories which offer the benefit of minimal tool retractions. Results are shown for spiraling paths generated from both convex and non-convex boundaries.


Author(s):  
H S Choy ◽  
K W Chan

Tool path generation based on contour-parallel offset has many practical applications, especially in pocket milling. However, the tool path segments offset from the pocket boundary usually form many corners. In milling operation, these corners with accumulated material will have an adverse effect on milling performance. This paper proposes an improved numerically controlled (NC) tool path pattern for pocket milling. Bow-like tool path segments are appended to a conventional contour-parallel tool path at the corner positions. The cutter loops along the appended tool path so that the corner material is machined progressively in several passes. By adjusting the number of appended tool path loops, cutting resistance can be controlled. The proposed tool path generation for dealing with different corner shapes was implemented as an addon user function in a computer aided design/manufacture (CAD/CAM) system. Cutting tests confirmed that the proposed tool path pattern is useful for clearing accumulated material at pocket corners while maintaining a higher cutting stability.


Author(s):  
Jinting Xu ◽  
Yukun Ji ◽  
Yuwen Sun ◽  
Yuan-Shin Lee

This paper presents a new spiral smoothing method to generate smooth curved tool paths directly on mesh surfaces. Spiral tool paths are preferable for computer numerical control (CNC) milling, especially for high-speed machining. At present, most spiral tool path generation methods aim mainly for pocketing, and a few methods for machining complex surface also suffer from some inherent problems, such as selection of projecting direction, preprocessing of complex offset contours, easily affected by the mesh or mesh deformation. To address the limitations, a new spiral tool path method is proposed, in which the radial curves play a key role as the guiding curves for spiral tool path generation. The radial curve is defined as one on the mesh surface that connects smoothly one point on the mesh surface and its boundary. To reduce the complexity of constructing the radial curves directly on the mesh surface, the mesh surface is first mapped onto a circular region. In this region, the radial lines, starting from the center, are planned and then mapped inversely onto the mesh surface, thereby forming the desired radial curves. By traversing these radial curves using the proposed linear interpolation method, a polyline spiral is generated, and then, the unfavorable overcuts and undercuts are identified and eliminated by supplementing additional spiral points. Spline-based technique of rounding the corners is also discussed to smooth the polyline spiral, thereby obtaining a smooth continuous spiral tool path. This method is able to not only greatly simplify the construction of radial curves and spiral tool path but also to have the ability of processing and smoothing complex surfaces. Experimental results are presented to validate the proposed method.


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