Studies on the Action Mechanism of Flexible Brush Using Magnetic Abrasive Finishing

• Main Authors: Peng-Yu Wu, 吳芃豫
• Other Authors: Rong-Tsong Lee
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/ymrr3a

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 107 === 　　In order to observe the structure and mechanism of the flexible magnetic abrasive brush (FMAB), this research uses a self-developed observation device of flexible magnetic brush. The experiments are divided into two parts: the workpiece is stationary or rotating. FMAB is formed by iron particles with a particle size of 40-62 μm. The effects of load (0.25 ~ 10 N), iron particle weight (0.1 ~ 0.5 g), magnetic brush forming method (natural forming, fixture forming, preload forming), dry or wet magnetic brush (adding alumina abrasive and kerosene) on the porosity, the height, the contact area of magnetic brush, and the friction coefficient are investigated. When the workpiece is stationary, the iron particles in natural forming FMAB is not completely arranged according to the direction of the magnetic line; Fixture forming FMAB is relatively uniform; Preload forming FMAB is the most compact. The change process of the magnetic brush by the load is sequentially deformed by the tip, and then broken and rearranged into a short and dense magnetic brush. On the other hand, the porosity of the FMAB gradually decreases to a saturation value as the load increases. At light load, the porosity of the preload forming FMAB is smaller than that of the natural forming and fixture forming FMAB. When the workpiece is rotating, the contact area between FMAB and workpiece rises sharply, and the height of FMAB drops sharply at load less than 1 N, but they tend to be gentle at load higher than 1 N. In addition, under light load, the contact area of the preload forming FMAB is larger than that of fixture forming FMAB, and the magnetic brush height is also lower; under heavy load, all FMAB heights are close to 0.6 mm, and the contact area are close to 115 mm2. On the other hand, the friction coefficient of the preload forming FMAB under light load is 0.4, which is higher than the other two FMABs (0.2). The friction coefficient under heavy load is 0.2. 　　When alumina abrasives are added into the iron powders, the alumina abrasive exists in the gap between the magnetic brushes in the form of agglomerates under light load. As the load increases, the magnetic brush gap becomes smaller, and the alumina abrasive agglomerates are also dispersed between the iron particles. In addition, the friction coefficient increases from 0.2 to 0.23 as alumina abrasives are added into the iron powders. On the other hand, the FMAB composed of iron powder and kerosene has the lowest friction coefficient (0.15). The FMAB composed of iron powder, kerosene and alumina abrasive has the highest friction coefficient (0.25).