Study on process parameter of high performance laser cutting machine tool for copper sheet
A high performance NC laser cutting machine tool for copper sheet is designed, emphasis discussing the components of NC laser cutting machine tool and design points. Performance of high power semiconductor pulse micro-cutting of copper sheet is studied and several key parameters are given by changing assistant gas and process parameters. The experimental results show that the best cutting quality can be obtained when argon is used as assistant gas, and oxygen is on the contrary. Also, in a certain range, improving laser power and cutting speed can help in decreasing laser cutting gap, minishing heat affected area, and achieving better cutting quality.
Laser welding of aluminum alloys: from fundamental investigation to industrial application
Laser beam welding of aluminum alloys is rendered difficult by their specific material properties. On the other hand the productivity and quality of the laser process is very attractive for the manufacturing of light-weight constructions for e.g. all kinds of vehicles. In many years of research a fundamental understanding of the relevant technological and metallurgical mechanisms has been acquired. This allows to offer guidelines for a successful adaptation of the welding process to specific needs of applications. Factors relevant for deep penetration threshold, process efficiency, process stability and for minimizing metallurgical defects are discussed. Strength values of butt and overlap joints are presented. The results achieved allows us to recommend the laser technique for near-to-production investigations and series application, today.
ROOM- AND HIGH-TEMPERATURE MAGNETIC PROPERTIES OF Sm(CobalFexCu0.088Zr0.025)7.5 (x=0.30) SINTERED MAGNETS
The effect of Fe content on room- and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5 (x=0-0.30) sintered magnets, prepared by the conventional powder metallurgy method, has been systematically studied. With increasing Fe content, the remanences BT and maximum energy products (BH)max at room temperature gradually increase and reach optimal values of 1.055 T with x=0.27 for BT, and 205 kJ/m3 with x=0.21 for (BH)max, respectively, and then drop sharply with further Fe increase. An excessive addition of Fe (x≥0.24) results in rapid deterioration of permanent magnetic properties due to the formation of a considerable amount of FeCo soft magnetic phase. It was found that the effect of Fe content on high temperature stability is huge. The lower the Fe content, the smaller the temperature coefficient of coercivity. When x=0.07, a temperature coefficient of coercivity of -0.14%/K (293-723 K) can be achieved, as compared with -0.23%/K for x=0.21. BT of 0.725 T, bHc of 517 kA/m, iHc of 764 kA/m, and (BH)max of 95 kJ/m3 at 723 K were obtained, and the B-H demagnetization curve remains a straight line.