Ke Gao, Xiaoqin Zhou, Rongqi Wang, Mingxu Fan and Haochen Han
Compared with the high stiffness of traditional CNC machine tools, the structural stiffness of industrial robots is usually less than 1 N/µm. Chatter not only affects the quality…
Abstract
Purpose
Compared with the high stiffness of traditional CNC machine tools, the structural stiffness of industrial robots is usually less than 1 N/µm. Chatter not only affects the quality of robotic milling but also reduces the accuracy of the milling process. The purpose of this paper is to reduce chatter in the robotic machining process.
Design/methodology/approach
First, the mode coupling chatter mechanism is analyzed. Then the milling force model and the principal stiffness model are established. Finally, the robot milling stability optimization method is proposed. The method considered functional redundancies, and a new robot milling stability index is proposed to improve the quality of milling operations.
Findings
The experimental results prove a significant reduction in force fluctuations and surface roughness after using the proposed robotic milling stability optimization method.
Originality/value
In this paper, a new robot milling stability index and a new robot milling stability optimization method are proposed. This method can significantly increase the milling stability and improve the milling quality, which can be widely used in the industry.
Details
Keywords
Abstract
Purpose
The purpose of this paper is to reduce the acoustic noise of helicopter ducted tail rotor.
Design/methodology/approach
To predict the noise accurately, a thin-body boundary element method (BEM)/Ffowcs Williams–Hawkings method is developed in this paper. It is a hybrid method combining the BEM with computational aeroacoustics and can be used efficiently to predict the propagation of sound wave in the duct.
Findings
Compared with the experimental results, the proposed method of acoustic noise is rather desirable.
Practical implications
Then several geometry parameters are modified to investigate the noise reduction of ducted tail rotor by using the numerical prediction method.
Originality/value
The aerodynamic and acoustic performance of different modification tasks is discussed. These results demonstrate the validity of design parameters modification of ducted tail rotor in acoustic noise reduction.
Details
Keywords
Abstract
Purpose
By reducing the coating thickness of the weak scattering source, the coating weight of the absorbing material can be reduced by 35% with little effect on the RCS.
Design/methodology/approach
To alleviate the weight-increasing problem caused by a large number of coating of absorbing materials, a method for zonal coating of absorbing materials for a stealth helicopter was proposed. By appropriately reducing the thickness of the coating at the secondary scattering locations, the amount of coating used is significantly reduced.
Findings
Compared with the full-coated, the zonal coating scheme achieves the corresponding RCS reduction effect.
Practical implications
Zonal coating design can achieve the effect of reducing coating weight and cost.
Originality/value
The effects of different coating methods on RCS were verified by electromagnetic scattering simulation, and the applicability of the zonal coating design of the absorbing material to the stealth helicopter was verified.