Materials Science Forum Vols. 697-698

Abstract: By the characteristics of gun drill and the mechanisms of DF (Double Feeder) system of outside the chip, and analyzing the processing characteristics of titanium alloy and the characteristics of small diameter deep hole, the drilling device DF system of gun drill is designed, and in order to better guarantee the accuracy of parts, the monitoring system between input oil installation and gun drill fixture are designed also. The device of drill the small diameter deep hole of titanium alloy, the value of surface roughness of the parts are Ra3.2-0.4μm and the phenomenon of the ring scratches eliminated.

Abstract: An approach of calibration method for 3D sensing scheme based on shifted point array encoding is presented. Initially a 3D calibration benchmark is established in object space, the camera subsystem can be calibrated with the benchmark. The projection optics subsystem is bounded with camera subsystem in this sensing scheme so a constraint condition is imposed on both subsystems. Therefore it is possible to calibrated projection subsystem by introducing a concept of benchmark transmission. Once both subsystems have been calibrated, the 3D coordinates of range image can be obtained with moderate accuracy. The coordinate difference between measured data and prescribed benchmark is used to define a square-error based objective function, leading to a non-linear equation. By solving this equation, one is able to determine the required parameters of the system configuration. Experiment results show that, after proposed calibration procedure, the 3-D sensing scheme based on point array encoding is able to achieve such an accuracy as the standard deviation in X direction is 0.29mm, 0.24mm in Y direction, and 0.29mm in Z direction, respectively, for a measuring volume of 300×300×80mm³.

Abstract: After being located, cutting force and torques will exert on a workpiece during the machining operation. In order to guarantee the location accuracy and production safety, the feasible clamping forces must be planned to stabilize the workpiece in the entire processing. Therefore, the workpiece stability is taken as a core to create a deterministic algorithm to the application region of clamping forces for the complex workpiece. Firstly, on the basis of the combination of the screw theory with the linear programming technology, an analysis algorithm is subjected to judge the workpiece stability. Secondly, according to the surface discretization method, a deterministic algorithm is further established to plan the application region of clamping force by analyzing the workpiece stability at all nodes in sequence. The proposed method can be utilized for the determination of the application region of clamping forces as well as the verification of the feasibility of the magnitudes of clamping forces.

Abstract: In order to optimize the MIG welding procedure of aluminum alloy with longitudinal magnetic field and improve the mechanical property, effect of longitudinal magnetic field frequency on microstructure and properties of surfacing layer were investigated. The results show that when the additional longitudinal magnetic field was introduced into welding process, grain was refined, the wear resistance and tensile strength of the surfacing layer were improved as longitudinal magnetic field frequency increased. When frequency of magnetic field is 20 Hz and exciting current is 15 A, effect of grain refining is the best and the mechanical property is the highest. But when exciting current continue to increase, grain became coarse and the mechanical property decreased. So it is concluded that grain was refined and the mechanical property of the surfacing layer were improved under longitudinal magnetic field. But magnetic field frequency has an optimal value; otherwise grain refining and the mechanical property can’t achieve the best effect.

Abstract: Side wrinkling may be produced during rotary-draw bending process of thin-walled rectangular 3A21 aluminum alloy tube if the process parameters are inappropriate. To study the side wrinkling behavior, a three-dimensional finite-element model of the process was developed based on ABAQUS/Explicit code and its reliability was validated by experiment. Then, the side wrinkling characteristics of the tube were investigated. The results show that the side wrinkling wave height in the inner edge of the tube is smaller than that in the out edge of the tube, and the side wrinkling wave height in the neutral layer of the tube is minimal. With the bending process, the side wrinkling wave goes through producing, developing and stabilizing three stages in turn. After bending angle reached 30°, the side wrinkling wave height keeps almost unchanged. Furthermore, the number of the half side wrinkling wave increases evenly.

Abstract: The effects of weld current, voltage, frequency and duty cycle on weld forming performance were investigated in SAW (Submerged Arc Welding) with square wave AC mode. The results showed that the penetration increased with the decrease of frequency and increase of duty cycle, but weld width showed the opposite change tendency. Furthermore, some experiments were implemented to analyze the effect of wire extension length and arc voltage on bead appearance. All of these experimental data could provide proper parameters for the lead arc and the trail arc in tandem SAW using square wave AC and also testified square wave AC was preferred over DC and traditional 50Hz AC. The square wave AC power source could be applied widely in tandem SAW.

Abstract: The hardening layer of blanking boundary could enhance structure intensity and wear resistance of blanking work piece evidently. Therefore it could enhance fatigue strength and the working life of work piece greatly. This paper carried through fine-blanking with negative clearance processing experiment for the sheet with different hardening index and measured the blanking force and the punch stroke relations curves. The micro hardness of the blanking work pieces sheared surface were measured by Vickers Hardness instrument(MH-6), which obtained the relations curves of punch stroke and the micro hardness of the blanking work pieces. The level of working hardening were compared with different hardening index materials by fine-blanking with negative clearance, and the blanking work pieces working hardening were enhanced evidently by fine-blanking with negative clearance.

Abstract: The workpieces of fine blanking with negative clearance were obtained through the fine-blanking with negative clearance processing experiment. The fractography photographs of workpieces shearing surface were scanned by scanning electron microscope (SEM), and the characterization parameters and quality standard of workpieces shearing surface with negative clearance were analyzed in the processing of blanking. According to the characterization parameters and quality standard of workpieces shearing surface with negative clearance, the workpiece with the length ratio of burnish band, deflection error, rollover error and blanking burr were analyzed qualitative. The findings have a certain reference value to the blanking related profession.

Abstract: The plastic analysis software DEFORM was used to simulate the blanking process of metal plastic without burr. Based on theory of the rigid FEM, the geometry model used for blanking with a negative clearance was established. The facts of influence the quality of the blanking work pieces were analyzed and concluded, at the same time, the parameters were indicated to improve the quality of the blanking work pieces. Through the experiment, the blanking load was measured with different clearance, thickness and material in group. The reciprocity between these facts was analyzed and the clearance was optimized. After the blanking load was regress analysis, the coefficient of the load and these facts were researched. Using quality analysis of the work pieces in the experiment, the thickness and the material were obtained which were suitable for blanking of metal plastic without burr. The reactions which were used to separate the metal were studied, which offered thereunder for proper remaining based on the better quality and smaller blanking load.

Abstract: An industrial experiment was carried out to study the characteristics and formation mechanism of segregation in semi-continuous direct-chill (DC) casting of Φ300mm aluminum alloy billet with ultrasonic radiation of different powers. Results show that both microsegregation and macrosegregation of solute elements Zn, Mg, Cu are improved remarkably when ultrasonic vibration is applied to A1-Zn-Mg-Cu alloy. Meanwhile, the higher power of ultrasonic vibration is, the more homogeneous distribution of solute elements becomes, and then the more effective improvement of segregation is achieved. With a 240W ultrasonic treatment (UST), the intra-grain solution degree of elements Zn, Mg and Cu increases by 35.8%, 41.8% and 40.2% respectively while the macrosegregation ratio decreases by 10.3%, 7.4%, 6.7%. Physical and chemical effects caused by ultrasonic field exert a positive impact on the solute elements diffusion, grain refinement, the depth of sump and solution degree et al, which contribute to the improvements of segregation.