5-Axis tool path smoothing based on drive constraints

Abstract

In high speed machining, the real feedrate is often lower than the programmed one. This reduction of the feedrate is mainly due to the physical limits of the drives, and affects machining time as well as the quality of the machined surface. Indeed, if the tool path presents sharp geometrical variations the feedrate has to be decreased to respect the drive constraints in terms of velocity, acceleration and jerk. Thus, the aim of this paper is to smooth 5-axis tool paths in order to maximize the real feedrate and to reduce the machining time.Velocity, acceleration and jerk limits of each drive allow to compute an evaluation of the maximum reachable feedrate which is then used to localize the areas where the tool path has to be smoothed. So starting from a given tool path, the proposed algorithm iteratively smoothes the joint motions in order to raise the real feedrate. This algorithm has been tested in 5-axis end milling of an airfoil and in flank milling of an impeller for which a N-buffer algorithm is used to control the geometrical deviations. An important reduction of the measured machining time is demonstrated in both examples.

5-axis local corner rounding of linear tool path discontinuities

“…The solutions based on a modification of the tool path in the Machine Coordinate System [13][14][15] have two main drawbacks. First, it is difficult to control the geometrical deviation on the workpiece resulting from a modification of an axis movement.…”

“…In 5-axis, global smoothing techniques are also widely studied. Different solutions can be used to smooth the orientation: quaternions [7,8], spherical B-Splines [9,10], position and orientation curves [11,12], drive movement smoothing [13][14][15].…”

Dual-Bézier path smoothing and interpolation for five-axis linear tool path in workpiece coordinate system

“…This method decreases tracking error for each axis in machine tools. Beudaert et al 25 proposed a five-axis tool path smoothing method by taking the drive constraints, such as maximum speed, acceleration, and jerk, into consideration. It can increase the average feedrate effectively.…”

Collisionless tool orientation smoothing above blade stream surface using NURBS envelope

“…Vahebi Nojedeh et al (2011) developed an error estimation model based on kinematic transformation concepts and used it to calculate the volumetric overall error. Beudaert et al (2011) smoothed five-axis tool paths to maximize the real feed rate and to reduce machining time. Abele and Korff (2011) presented possible methods and solutions to prevent collisions and collision damages of machine tool components, especially the main spindle unit.…”