Papers by Author: Guo Fu Gao

Abstract: In order to solve the problem of efficient and accurate tool change in vibration system, horn with a conical hole and a center via hole which connects tool is proposed. In connection with the shape of the horn, an equivalent model of the horn is built up. Based on the transmission matrix method, the frequency equation and magnification factor of the horn is deduced. And the finite element method was employed to verify the derived formulas. Compared the simulation results with the theoretical results, the derived formulas can be applied to design the complex horn.

Abstract: In order to achieve the local resonance of flexible-rod whetstone-seat vibration subsystem of the ultrasonic honing device, and using the analysis method of control theory, to regard the flexible-rod and whetstone-seat as the independent part in dynamics, their natural frequency and the vibration displacement function respectively are calculated by adopting the model of vibration with uniform section rod. Then the relationship between the natural frequency and the geometrical parameters of flexible-rod and whetstone-seat are established. The experiments shows that the computed result approximates the actual of flexible-rod whetstone-seat vibration system relatively. For the design of flexible-rod whetstone-seat vibration system with better vibration performance, it has the significant reference value.

Abstract: In order to achieve the work-piece surface quality control, Based on the formation mechanism of surface roughness and generating mechanism of material’s surface, considering the tool parameters and feed per tooth, to modify the maximum residual height’s formula of surface. Based on formation characteristics of machined surface and the elastic-plastic deformation theory of work-piece material, Got a simplified model of the elastic-plastic deformation of the work-piece surface,and according to the molecular-mechanical friction theory ,the calculation method was presented to investigate elastic-plastic deformation of machined surface . By combining the surface residual height calculation formula with the calculation method of elastic-plastic deformation, has built the theoretic model of the milling surface roughness , can forecast to the work-piece surface roughness, as well as provide theory basis for the selection of cutting parameters and optimization.

Abstract: The experimental research on ultrasonic vibration assisted milling non-ablating carbon fibre reinforced carbon composite was carried out by employing uncoated tungsten carbide milling cutter, in order to reduce the machining cost and improve the surface quality of workpiece. According to the experimental results, the tool wear was reduced and the surface quality of milled carbon fibre reinforced carbon composite was improved. Compared to traditional milling method, the flank wear land was narrowed and it dominated by abrasive particles wear mechanism. The wear trace was even and wide, with width of 7-8μm; while the rake face was worn in the mode of adhesion wear mechanism. Most of carbon fibres were cut off directly and there were little fracture, pull-out and delamination; the matrix phase was removed nearly in hybrid of brittle and ductile regime and surface damage was small.

Abstract: Although particle reinforced metal matrix composites possess excellent physical properties, its machining performance is rather bad because of its specific structure. It is difficult to obtain good cutting effect by traditional machining method. So machining has become the bottleneck which strictly restricts its industry application. This paper mainly focuses on both wear characteristics of different tool materials and material removal mechanism in ultrasonic milling high volume fraction particle reinforced metal matrix composites SiCp/Al. An acoustic device for ultrasonic vibration milling was developed to introduce the ultrasonic vibration into the traditional machining process. Through the contrast experiment of traditional milling and ultrasonic vibration milling SiCp/Al, the mechanism of tool wear and characteristics of surface topography were analyzed. The experimental results showed that the surface integrity and tool life in the ultrasonic vibration milling SiCp/Al were improved. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: The experiment of resin-bonded CBN wheel dressing using a diamond dresser assisted with longitudinal ultrasonic vibration along the direction of depth of cut was carried out and the dressing characteristics and grinding performance were discussed in the present paper. The influence of acoustic parameters on the topography of CBN wheel was studied to check the effectiveness of dressing for this method. The experimental results showed that the higher the ultrasonic frequency is, the better the wheel topography. The grinding on K9 optical glass and high speed steel has achieved higher G-ratio than that of traditionally mechanical dressed CBN grinding wheel. The ground surface of high speed steel is better than that of K9 optical glass. According to the interferometer images, it was concluded that the grinding of high speed steel was in ductile cutting regime, while removal of K9 optical glass was in brittle fracture regime.

Abstract: The brittleness, plasticity, super-plasticity and the removal mechanisms of critical fragmentation of the nano ZrO2 ceramics were investigated. The formula of critical ductile grinding depth of the common engineering ceramics was inapplicable to the nano-ZrO2 ceramics. A new formula of critical ductile grinding depth of the nano ceramics was established. The ultrasonic vibration grinding experiments showed that the critical ductile grinding depth of the ceramics was 15μm by conventional grinding, but the increment of the critical ductile grinding depth was 60 percent by ultrasonic grinding. The critical ductile grinding depth increased to 25μm. Analyzed by means of SEM, it was transgranular cracking during its cracking process. The nano-ZrO2 ceramics have high toughness so the critical ductile grinding depth increased. The shape, length, width and thickness of the grindings differed greatly from which obtained by conventional grinding.

Abstract: The Large-grit bronze-bonded diamond grinding wheel was shaped employing a diamond dresser with elliptic ultrasonic vibration assistance, to solve problems such as high cost, low dressing speed and low accuracy. And the truing and conditioning performance of this new method was discussed for its effectiveness. Experimental results showed that the roundness error of elliptic vibration dressed diamond grinding wheel is less, and the bond tail was cut shorter and the chip capacity became larger than that of mechanical dressed one. The SEM observation showed for the present dressing method the material removal mechanism is ductile removal of bond material and micro breakup of gains and this method can perform truing of large-grit diamond grinding wheel as well as conditioning in one step.

Abstract: Particle-reinforcement aluminum-based metal matrix composites (MMCs) are widely applied in the aviation, aerospace and military fields due to their excellent physical and mechanical properties. But the further application of the materials is hampered owing to its difficultly machining characteristics. There are unique advantages while cutting hard and brittle materials with ultrasonic vibration. The ultrasonic vibration high-speed milling (ultrasonic milling) is a reasonable cutting method in which combined the advantages of high-speed milling (conventional milling) and ultrasonic milling. The machining performances of high volume SiCp/Al MMCs were studied by conventional milling and ultrasonic milling in this paper. The influences of the milling parameters on the milling force were investigated in the experiment. In addition, the wear and mechanism of tool were analyzed in ultrasonic milling. The results show that the cutting force, abrasive wear were reduced, and tool lives were increased effectively during ultrasonic milling of SiCp/Al MMCs.

Abstract: The mechanical model of stress field was established in grinding with/without ultrasonic vibration assistance, based on indentation fracture mechanics. Compared with the stress field in conventional grinding, the research has shown that the grinding stress field changes periodically with the vibration process of the moving grains in ultrasonic grinding. In a vibration cycle, the grains interfere with the workpiece within the time of T+Δt and cut off the material from the workpiece surface. Meantime, the large impact force between the grinding wheel and the workpiece results in stress field on the ground surface. In other period of vibration cycle, the grains are detached from the workpiece surface, and there exists no interaction between them. The grinding force disappears, so does the grinding stress field.