Smoothing strategy for corner of small curvature radius by abrasive waterjet machining

Abrasive waterjet(AWJ)is widely applied in 2D machining as it offers high machining efficiency and low machining cost.However,machining a 3D surface,especially for a small curvature radius freeform surface(SCRFS),results in over-erosion of the corner,and has been one of the greatest issues of AWJ.To solve this problem,a local smoothing algorithm for SCRFS is developed by the junction of two linear segments at the corner by inserting cubic second-order B-spline to smooth the nozzle path and posture under the setting tolerance error,which is aimed to avoid over-erosion due to the change in dwell time.Analytical solutions of the smooth corner position and orientation of the nozzle path are obtained by evaluating a synchronization algorithm.According to the set tolerance error of the nozzle position and orientation,the interpolation of the smooth path of the corner meets the constraint conditions of the linear feed drive.Path simulation and experimental results show that the proposed method is validated by the experimental results and has been applied to the integral blisk machining of an aero-engine.

Continuities of Progressive and Mixing Algorithm for Surface Modeling and Editing

The progressive and mixing algorithm(PAMA) is a method for surface modeling and editing,which is developed for effective and flexible applications in many environments,such as computer-aided design(CAD) and computer-aided geometric design(CAGD).In this paper,the construction scheme and continuities of PAMA are discussed,which provide a mathematics analysis of PAMA.The analysis and results show that the PAMA provides a new method of surface modeling and editing with four more degrees of freedom for designers to manipulate a 3D object.

An on-line tool path smoothing algorithm for 6R robot manipulator with geometric and dynamic constraints

The tool path smoothness of the industrial robot directly influences the dynamic performance of its motion control. Therefore, it is important to smooth the path that is composed of small linear segments, in order to achieve continuous and smooth movement.This paper uses the FIR filter interpolation method to generate the smooth tool tip position and tool orientation trajectory for robot manipulators with 6 rotational(6R) joints. The geometric smoothness and motion interpolation are achieved in one step.The maximum velocity and acceleration of joints are constrained when calculating the time parameters of the FIR filter. By specially designing the overlapping time at transition corners, the tool tip position and tool orientation deviations are all constrained in the workpiece coordinate system. Considering the complexity of the inverse kinematics of the robot, in order to constrain the velocity and acceleration of robot joints, this paper proposes a simplified method which directly establishes the relationship between joint motion and tool motion through the derivative of joint motion to tool motion without considering the inverse kinematics. Simulation and experiment results show that the algorithm can generate continuous acceleration commands of the tool tip position and tool orientation within the corner error tolerance. The preset velocity and acceleration limitations of six joints are all constrained well. Comparisons with existing algorithms demonstrate advantages of the proposed method.