Abstract
With the rotary cutting system of king grass shredder as the research object, this paper established finite element models for rotating shaft, rotating shaft-belt pulley, rotating shaft-rotary cutting part and rotary cutting system and analyzed the influences of belt pulley and rotary cutting part on the dynamic characteristics of rotary cutting system. The results showed that the belt pulley and rotary cutting part had a great influence on the second order critical speed of rotary cutting system, and the rotary cutting part had a greater influence on the critical speed of first order forward precession than the belt pulley. Meanwhile, the critical speed of rotary cutting system that conformed to facts was calculated. There was a big difference between its first order and second order critical speeds, but the critical speed of first order backward precession was lower. Finally, it was found after analysis that the natural frequency of rotary cutting system was lower than the vibration frequency induced by belt drive, so the shredder can run safely.
Highlights
The speed of shredder, as a widely-used material shredding machine, directly influences its shredding efficiency, and the rotating speed is exactly an important indicator of the efficiency of shredder [1,2]
The dynamic characteristics of rotary cutting system of king grass shredder were analyzed, and the calculation and analysis results were of great reference value for the dynamic design of the king grass shredder
The rotary cutting system was simplified as follows: 1) the thread, chamfer, fillet and keyway in the model were removed; 2) the parts contained in the rotary cutting system were divided into three entities: rotating shaft, rotary cutting part and belt pulley; 3) it was assumed that the support stiffness of the bearings of rotating shaft part was all 1X107N/m
Summary
The speed of shredder, as a widely-used material shredding machine, directly influences its shredding efficiency, and the rotating speed is exactly an important indicator of the efficiency of shredder [1,2]. If the rotating speed exceeds the critical speed, the machine will vibrate and make noise. The safe operation of the equipment will be affected [3,4]. This shows that critical speed is a very important parameter in the design process of rotary machinery. The rotary cutting system is a key working part of shredder, and its critical speed plays an important role in the operating performance of shredder [5,6]. The dynamic characteristics of rotary cutting system of king grass shredder were analyzed, and the calculation and analysis results were of great reference value for the dynamic design of the king grass shredder
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