Advanced Materials Research Vols. 538-541

Abstract: The basic hypothesis of this article focuses on the study changes in mechanical properties of stainless steels XCr17Ni7MoTiN under surface finish when drilling. The problem of drilling holes with diameter D=10 mm resides in the fact that 30 to 40% of these holes do not comply with prescribed requested requirements. This article presents the results of experiments focusing on the study of the damage process in helical drills with diameter d=10.0 mm when drilling into austenitic stainless steel XCr17Ni7MoTiN. This study also includes an analysis of accompanying phenomena in the cutting zone by measuring some selected parameters. Experimental results were verified in the production of holes in products for the food industry.

Abstract: Polycrystalline Diamond (PCD) tools are widely used while machining wood-based composites because of its outstanding hardness, thermal conductivity and abrasive resistance. However, the above mentioned beneficial properties such as super hardness also cause problems in manufacturing PCD tools using traditional process methods. The main problem now in manufacturing PCD tools is the low efficiency and difficulties while manufacturing PCD tools with complex curved surface. To manufacture PCD tools with complex curved surface more efficiently, in this paper, the mechanical structure, hardware circuit and software system of five-axis EDG CNC system are introduced. To satisfy the unique requirements of EDG, a proper mechanical structure of 5 CNC controlled axis and 2 manual axis are given, as well as the design of hardware circuit of EDG based on PCI Bus. The software system which is designed based on RT-Linux is divided into four modules: real-time cyclical tasks module, real-time gusty tasks module, non real-time tasks module and EDG process database. , This paper gives out the solutions of the specific functions of this special CNC system, including automatic measurement, automatic programming, automatic electrode wear compensation, and detection and control of spark gap. The detailed structure and organization of the software system is also provided. At last, through actual cutting experiments of woodworking PCD tools, the correctness and practicality of this system is verified.

Abstract: The technology of the NC electrochemical-mechanical composed cutting was used on cutting the GH710 alloy materials, and orthogonal experiment had been done to analyze the effects of parameters on cutting depth. The results show that the spindle speed and voltage are mainly two factors to affect cutting depth of the workpiece. Moreover, the results also identify the optimal machining parameters: Temperature of 45°C, Voltage 24V, Electrolyte pressure1.2MPa and Spindle speed1000 r/min.

Abstract: Development of cutting tools is basic condition for rationalization of process cutting because it goes out from need of processing new constructional materials. From view of tool it takes application progressive cutting materials. Cutting tools so relevantly make for accomplishment main demand on methods of cutting; it is provision of high productivity production and attainment of desideration of finish surface. It is known, that cutting property of cutting tool is influence by many factors.

Abstract: This paper presents the additional work of the previous research in order to investigate the relations of the cutting conditions and the various air blow applications which affect the surface roughness. The suitable cutting condition is determined for the aluminum (Al6063) with the ball end milling by utilizing the response surface analysis referring to the minimum surface roughness. The cutting force is monitored during the cutting to analyze the surface roughness. The dynamometer is employed and installed on the table of 5-axis CNC maching center to measure the in-process cutting force. The models of surface roughness and cutting force are calculated by using the multiple regression analysis with the least squared method at 95% significant level. The experimentally obtained results showed that the surface roughness can be well explained by the in-process cutting force. The prediction accuracy and the prediction interval have been presented to verify the obtained surface roughness model at 95% confident level.

Abstract: This research presents the integration of the surface roughness and chip formation monitoring by using the cutting force and the cutting temperature during the in-process turning. The surface roughness prediction model is proposed by utilizing the response surface analysis with the Box-Behnken design. The effects of cutting parameters on the cutting force and the cutting temperature are investigated. The cutting force and the cutting temperature are measured to help analyze the relation between the surface roughness and the cutting conditions. The models of the cutting force ratio and the cutting temperature are also proposed based on the experimental data. The in-process monitoring of chip formation is developed to detect the continuous chip and the broken chip by utilizing the power spectrum density of dynamic cutting force and the variance of the dynamic cutting temperature.The broken chip formation is required for the reliable turning operation. The algorithm is proposed to obtain the broken chip by changing the cutting conditions during the cutting process based on the cutting force and the cutting temperature. It has been proved by series of cutting experiments that the proposed surface roughness model can be effectively used to predict the surface roughness, and the broken chip is well identified by the proposed method.

Abstract: Inconel 718 is used for high-temperature applications in aerospace, nuclear, and automotive industries due to its resistance, at high temperatures, to corrosion, fatigue, creep, oxidation, and deformation. Unfortunately, these same qualities also impair its machinability and researchers have investigated on ways to machine it economically. Some unconventional machining practices such as: Plasma Enhanced and Laser Assisted Machining etc. have been applied. However these practices increase the machining cost. This research investigated the viability of high speed end milling of Inconel 718 using circular Silicon Nitride (ceramic) inserts under room temperature conditions. Tool wear (flank and notch wear), machining vibration amplitude and average surface roughness were evaluated for the feasibility analysis. A vertical CNC mill was used to machine Inconel 718 samples using different combinations of three primary machining parameters: cutting speed, feed, and depth of cut. Vibration data acquisition device and Datalog DasyLab 5.6 software were used to analyze machining vibration. Scanning Electron Microscope (SEM) and surface profilometer were utilized to measure tool (flank and notch) wear and surface roughness, respectively. It was observed that the machining vibrations, in high speed machining, was reasonable (0.045 V on the average). This resulted in acceptable tool wear (averages: flank wear = 0.25 mm, notch wear = 0.45 mm) and semi-finished surface roughness (0.30 µm) measured after every 30 mm length of cut. Thus, room temperature high speed machining of Inconel 718 using circular silicon nitride inserts is a practical option.

Abstract: The effect of liquid-die-forging pressure on the microstructure and mechanical properties of A390 sloping swash-plate forming was investigated. It was found that the microstructure and comprehensive mechanical properties of the alloy were effectively improved by the liquid-die-forging pressure applied on the A390 aluminum melt. With continuous increasing of the specific pressure, the grain size of primary silicon gradually decreased, the fraction of eutectic silicon obviously decreased, and its morphology was granular mainly. When the applied pressure was 181 MPa, the size of primary silicon was reduced to about 20 μm. When the casting temperature of the alloy was 820 °C, the mould preheating temperature was 240 °C and the forging casting specific pressure reached 181 MPa, the sloping swash plate without macro-defects, and with the internal compact-gain structure and excellent mechanical properties can be obtained.

Abstract: In order to analyze the relation between wood surface roughness of plantation-Mytilaria laosensis and sanding parameters, two orthogonal experiment were performed. The results show that the mesh of the sandpaper has remarkable influence on wood surface roughness of plantation-Mytilaria laosensis,but the feeding speed and sanding thickness don’t; when the mesh of the sandpaper is 150, the feeding speed is 7 m/min and sanding thickness is 0.6 mm during the first sanding and the mesh of the sandpaper is 240, the feeding speed is 8m/min and sanding thickness is 0.15mm during the second sanding, the smallest roughness (Ra) was obtained as 2.79μm. Considering production efficiency, changing feeding speed into 9 m/min in the theory optimization scheme, engineering optimization scheme was obtained, and the wood surface roughness (Ra) is 2.80μm.

Abstract: The working medium of the pneumatic control system is air, which is delivered to each branch pipe through the role of the governing valve , and then the divided gas delivers the compressed air to each solenoid valve and pneumatic control valve. The solenoid valves and pneumatic control valve is connected through terminals and PLC, PLC obtains corresponding signal and makes judgment, conveying signal which is delivered to the solenoid valves and pneumatic control valve to achieve ventilation and breathe action, and finally the gas reaches the cylinder . The cylinder can complete the valve body on and off, so as to realize the pneumatic system of the automatic control.