Advanced Materials Research Vol. 500

Abstract: In order to find out the cutter disrepair principle and provide a valuable reference for the design, production and use of the heavy-duty hard alloy cutter, have experiment study on machining the heat-resistant steel-the 3Cr-1Mo-1/4Vsteel. First, have impact disrepair experiments with several types of different grooves milling inserts, and find out the difference of the impact disrepair invalidation types among them, and build the impact disrepair life cumulating distribution function mathematic model. Second, based on the adhering disrepair experiments, find out the difference of the adhering disrepair invalidation types, build the quantitative mathematic relation between milling temperature and maximal adhering disrepair depth on rake face of the cutter, and analyze the rule that the milling temperature affects the adhering disrepair. And then, on the basis of the scene machining, have analysis on cutter disrepair phenomenon and mechanism under the joint action of force and heat, so to provide a theoretical basis on how to avoid premature failure of the tool for the actual production process.

Abstract: This paper presents a design idea of PCD tool drilling CFRP and analysis of experiment of two types PCD tools machining CFRP. Firstly, parameters of PCD drill including cutting edge type, clearance angle and two point angles were improved by the mean of surveying variation of axial load values and quality of CFRP hole exit. Secondly, two types of burrs were defined from aspects of burr generated mechanism by observing plenty of burr pictures. Lastly, making use of MATLAB software, function between axial load and hole numbers were ensured by data fitting in tool life analysis.

Abstract: This paper researched experiment results and analysis of PCBN insert turning nickel-based HSTR GH 4169. According to the curves and pictures, discuss the relationship of cutting parameters (cutting speed, feed and cutting depth) and some indexes (cutting force, cutting temperature and surface roughness). In addition, observed chip burr patterns, tool wear types and white layer statuses, and quantitatively analyzed their factors from the perspectives of cutting force and temperature, and put forward corresponding measures. The studies above were based on future research of quantification.

Abstract: For its good processing flexible, economic and environmental protection performance, hardened steel GCr15 is used widely in car and energy industry. Although surface quality in machining process is not controlled well, that restricts application of hardened steel GCr15 extensive to a certain degree. Therefore, this study revealed the effect of cutting parameters on surface roughness. Also influence of cutting conditions on surface morphology and organization generation mechanism of subsurface were stuied for high-speed cutting hardened steel GCr15. Appear reasons of plastic side flow on surface was researched. Also, effect of tool wear on surface quality was studied as well. The research results provided theoretical basis for rational choice for high speed hardened steel cutting process.

Abstract: The slicing technology of hard-brittle materials by endless diamond wire saw has the advantages of higher moving speed of wire saw, better slicing quality, and thin kerf. According to the strength of wire saw, the cutting force and the random vibration of wire saw, the slicing parameters are optimized. As single crystal silicon is sliced, the constant feed force is less than 10N, the maximum pretension is 30N, and the highest moving speed of wire saw is 24m/s. But because the restrict of machine precision, the highest slicing speed is 16m/s.

Abstract: The research of cutting force and vibration has been gaining significant attention to improve machining efficiency and tool life in processing metals. In this paper, the plunge milling system is reduced to 3-DOF vibration system, and dynamical theoretical model and instantaneous undeformed chip thickness models are established based on dividing cutter tooth into finite number of small differential elements in the radial direction and discrete time domain. Based on regenerative chatter theory, the cutting force and vibration can be simulated by numerical algorithm. Compared the simulation results with experiments data, the milling force and vibration have a good agreement, which testify the correction of those models

Abstract: High cutting force, high cutting temperature and severe adhesion will be produced in the machining process of Ti-6Al-1.5Cr-2.5Mo-0.5Fe-0.3Si. Furthermore, there are critical needs to reduce the use of cutting fluid in machining process. This paper presents a friction force model under MQL condition. An experiment of turning titanium alloy was presented to test and analyze MQL effects. The mainly results were: (1) MQL can reduce the friction at the chip-tool interface when cutting parameters and matching parameters of MQL were chosen properly. (2) Degrees of serrated chips and chip morphology affected by different lubrication conditions were different.

Abstract: nconel 718 is one of the most commercially important superalloys but with very poor machinability. It has a very high yield stress and a high tendency to adhesion and work-hardening. A recent trend of improving the machining processes of difficult-to-cut materials is to move towards dry cutting operations. This paper presents an experimental study of the cutting forces in high speed dry milling of Inconel 718 using a milling cutter with coated carbide inserts. It is found that the peak cutting forces increase with an increase in chip load in a nonlinear way, but cutting speed does not show a significant influence on the cutting force for the range of cutting speeds tested in this study.

Abstract: Tool wear was investigated at the different cutting conditions in rough ball-end milling of Cr12MoV die steel using an indexable cutter with asymmetric inserts. The wear patterns on rake face and flank face of major insert and minor insert, and chip patterns were observed by VHX-600E large depth-of-view 3-D scanner. The relationships of tool wear and cutting conditions, and their mechanisms were discussed. The tool life was determined by the flank wear at No. 1 cutting condition. At Nos. 2-8 cutting conditions, the life of major inset and minor insert were determined by the wear of their rake faces and flank faces respectively. At No. 8 cutting condition, the tool wear was dominated by boundary wear, adhesion and diffusion wear, and the slight chipping. Both type and color of chips identified the cutting stability at the different cutting conditions.

Abstract: The wear-resistance performance of machined surface is an important factor in the evaluation of surface quality and precision in aerospace manufacturing industry. By using high-speed Ring-Block friction and wear machine (MRH-3), the influence of cutting parameters in milling aluminum alloy 7050-T7451 on wear-resistance of machined surface including friction coefficient and wear quantity are experimentally investigated. The wear-resistance is particularly sensitive to cutting speed and feed rate. The friction coefficient has marked drop trends as cutting speed increases. The influence of cutting speed on wear quantity is more complicated and the tendency of wear quantity was ascend in first and descend at last (v>900/min). The results show that the influence of cutting parameters on wear-resistance was also positively correlated with surface roughness and work-hardening of machined surface. The high work-hardening and surface quality had the promoting effecting on wear-resistance. The experiment and analysis results show that the machined surface by high speed cutting and lower feed rate has more superior in surface quality and wear-resistance performance comparing with conventional cutting speed.