Contents I. Introduction
The primary processing method in mechanical manufacturing industry is cutting. Different shapes of metal particles are produced according to the machinability and processing conditions of the workpiece material during cutting, which seriously affect the safety of the operator and the normal operation of the machine tool [1]. Thus the collection and discharge system of metal particles is necessary to ensure the processing quality and improve the production efficiency [2]. Among the metal particle conveying modes commonly used in current, the pipe-type particles conveyor has a wide range of applications. In the automatic production of CNC machine tools and multi-machines, the detection of the metal particles velocity flowing in the pipeline can effectively prevent the occurrence of pipeline blockage during the transportation process, so as to ensure the normal operation of the automatic machining cycle [3].
