Chip ignition in research on high-speed face milling AM50A magnesium alloy
The ignition of magnesium alloy chips is a problem during high speed dry machining in industry. It should be avoided in the practical production. Many factors including machining environment, material composition, tool geometry, cutting parameters etc. can influence the cutting processes. Among these factors, cutting parameters is one of most important elements to induce the ignition of magnesium alloys. AM50A is a commercial magnesium alloy which is widely used in industry. However, very few reports about the ignition conditions of AM50A magnesium alloy are available. In this paper, we investigated the ignition conditions of AM50A magnesium alloy at different cutting parameters. The relationship between ignition conditions and chip morphologies was further explored. The macro morphologies of the chips were observed by optical microscope and the micro structure were obtained by scanning electron microscope (SEM). It is found that the macro morphologies of chips can be characterized into powdered chip, tubular helical chip, acicular helical chip, and long belt chip, which correspond to the different ignition conditions. The powdered chips and acicular spiral chips are easily ignited. They have thinner lamellar thickness compared to the other two types of chips. These results may be used to analyze cutting process and prevent the chip ignition in dry machining magnesium alloy.
Effect of Cutting Parameters on Ignition of AM50A Mg Alloy during Face Milling
The ignition of magnesium alloy chips is an important problem during dry machining. In this paper, the influence of cutting speed, feed rate, and depth of cut on ignition of AM50A magnesium alloy during high-speed face milling was investigated. It was found that ignition could easily be caused under some cutting speed and feed rate when the depth of cut was fixed and ignition was rarely observed when the depth of cut was 80 µm. Moreover, the relationship between morphology of chip and frequency of ignition was explored. We found that intertwined chips easily produced ring of fire.
Kinemamtic analysis of flying-saw vehicle
The paper analyzes the kinematic motion of the flying-saw vehicle.After the analysis,it is concluded that the ac- celerating periods and decelerating periods in both forward and backward directions will follow sin~2αcurve and,in order to increase the sawing dimensional accuracy,flying-saw vehicle must come back as soon as possible while acceleration remains constant.Based on this premise,the paper gives out the equations of kinematic motion of the flying-saw vehicle in every sta- ges and one example result in a common situation.By now this method has been used in the real situation.