Discretizors and Interpolators for Five-Axis CNC Machines

Sarma, Radha; Rao, Aarthi

doi:10.1115/1.538896

Cited by 22 publications

(5 citation statements)

References 17 publications

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“…General CNC machine tools only have linear and circular interpolation functions, which cannot accurately track the intended curve trajectory, so the curve needs to be discretized to obtain the cutting position (CL) [5][6]. Therefore, the machining of complex parts on these machines is divided into two main steps.…”

Section: Introductionmentioning

confidence: 99%

Smoothing and compressing algorithm of toolpath with complex contour in NC machining

Zhang

et al. 2023

Int J Adv Manuf Technol

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The continuous short line segment processing method in CNC machining has the defect of frequent fluctuation of feedrate, which affects the quality and efficiency. For this problem, the local and global methods are common solutions. The local method is to insert transition curves at the corners to obtain a smooth toolpath, but this method does not essentially reduce the number of acceleration and deceleration, and it is difficult to insert transition curves between tiny straight sections. Although the global method can obtain smooth tool trajectories, the parametric interpolation method is not suitable for low-and mid-range CNC machines. The article proposes an adaptive tool path generation method with the original part contour as the research object and discrete the NURBS curves into smooth trajectories consisting of large segments of straight lines and circular arcs. The article mimics the crawling characteristics of snakes and designs a double-headed snake algorithm based on the least squares method to implement this process. First, given the start and end points of the curve, two snakeheads search for the maximum linear and circular segments that satisfy the error constraint in the curve direction. The winner will then be selected as the candidate track segment through a competition mechanism. Finally, all trajectory segments are connected to obtain a smooth tool path. Experiments show that the toolpath data of the method in this paper is reduced by 75.56% compared with commercial CAM software when the contour error threshold is the same, and the contour error is reduced by more than one order of magnitude when the number of toolpath segments is equal. In addition, the method in this paper can obtain a smoother machining surface and more stable cutting force, thus achieving a win-win situation of quality and efficiency.

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Section: Introductionmentioning

confidence: 99%

Smoothing and compressing algorithm of toolpath with complex contour in NC machining

Zhang

et al. 2023

Int J Adv Manuf Technol

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“…The determination of the forward step is one of the most important steps in the path discretization. 14 There are three approaches to determine the forward step length of the traditional CNC machining so far: iso-parameter, equal-chord length, and chordal deviation. 15,16 Iso-parameter method and equal-chord length method have not been widely used because of their own limitations, that is, the deviation is often beyond the tolerance for complex tool path geometry.…”

Section: Introductionmentioning

confidence: 99%

An improved path discretization method for automated fiber placement

2020

Journal of Reinforced Plastics and Composites

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In the automated fiber placement process, the continuous placement paths need to be discretized into a finite number of path points because the laying head cannot continuously trace the predetermined curved path. However, the discretization of the placement path, which is a spatial curve, will inevitably introduce error. In this paper, an improved path discretization algorithm is proposed for the fiber placement of complex double-curved structures. Firstly, the discrete error was decomposed into normal direction and binormal direction, and they are correlated with the laying process and their influences on the laying quality are discussed, respectively. Secondly, the relationship between the binormal error and the overlap of the tow is analyzed with differential geometry, and the influence of the normal error on laying force is discussed by the pressure experiment and the finite element method. Finally, the improved path discretization algorithm has been verified on double-curved surface and compared with the traditional path discrete algorithms. The results showed that the number of discrete path points decreases by 45.8% on average compared with the chordal deviation discretization algorithm and by 63.1% compared with the equal-arc discretization algorithm.

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“…Recently, their focus has moved to research on enhancing machining speed and surface quality. Sarma and Rao [1] had proposed a method for 5-axis machining interpolation, which takes into consideration angular feedrate in parametric curve interpolation, in order to improve low surface quality due to inadequate angular velocity. Fleisig and Spence [2] had applied the "nearly arc-length parameterized quintic-spline interpolation" method [3] to multiaxis machining, proposing an interpolation algorithm that simultaneously satisfies translational and rotational move of constant speed.…”

Section: Introductionmentioning

confidence: 99%