Materials Science Forum Vols. 800-801

Abstract: In the process of cutting, the problem of flying chips seriously affect the processor’s life safety and the processing environment of workshop. In order to study the characteristics of the chips flying, the authors selected five different kinds of commonly used milling insert, and use these milling insert in the dry milling experiments to study the process of cutting chips flying. In the paper, firstly, carried out flying track analysis on the chips, and concluded the chips flying theory, and then design the cutting experiment, through the statistical analysis of experiments data, to understand the influence of different insert groove chip and cutting parameters to chip flying, and puts forward suggestions on groove development of heavy-duty cutting inserts.

Abstract: This paper analyzed the serrated chip formation process and mechanism in high-speed milling of nickel-based superalloy GH706. Firstly, analyzed two theories of serrated chip formation: cyclical fracture theory and adiabatic shear theory. Secondly, used the simulation of chip formation in high-speed milling of GH706 process, and concluded that the two major theories have achieved dialectical unity when machining for such difficult machining materials. Finally experiments for serrated chip, when cutting speed exceeded 200/min, serrated chips became more obvious. Research has shown that for nickel-based superalloy, adiabatic shear instability of the unstable thermoplastic in the first deformation zoon become the leader of formation of serrated chip, followed as the speed increases, fracture aggravate the degree of serrated chip.

Abstract: This paper explores the drilling characteristics of GH3039 supper alloy. The machining of GH3039 is a difficulty which is commonly used in aircraft and engineer components of the aerospace industry. The spindle speed and feed per tooth are the major influence factors which are studied to gain large removal rate and predict the drilling characteristics. So the single factor test is carried out about spindle speed and feed per tooth. The results of the experiment show that the drilling force of GH3039 decreased with the increasing of spindle speed up to 900r/min which is larger than other metal drilling process. The small feed per tooth may obtain small drilling force. So too low spindle speed and large feed per tooth are not adopted in the GH3039 drilling process. The analysis of the chip formation also verifies the above characteristics. At the same time, the serious serrated chip is occurred which is adverse for the drilling. It has significant for other supper alloy real drilling process.

Abstract: High-temperature alloy is an important material in making critical aerospace engine parts, it is also used in weapons industry, energy, chemical, power, etc. In this article, DEFORM-3D software applications to establish a three-dimensional cutting model of high-temperature alloy GH4169. Combined with cutting experiment analysis the characteristics of the tool wear and cutting temperature by change cutting speeds, and optimized cutting parameters combined with experimental on tool wear.

Abstract: Fir tree groove broaching is prone to deformation, which affects the machining precision of rear wheel groove. The numerical broaching force is calculated to improve deformation of the processed round tank .This paper uses the planer to make cutting tests that are carried out in shaping machine to simulate the wheel broaching process and measures the cutting force in the experiment. After analyzing the unit numerical cutting force of GH4698 broaching is finally obtained. It provides a simple method to calculate the cutting force of wheel groove machining.

Abstract: Based on actual working condition, this paper takes the mold materials Cr12MoVwhich is widely used in car cover as research object, and uses the finite element software Deform 3D to establish three-dimensional finite element simulation model of milling hardened steel Cr12MoV process. Reliable material model, chip separation criterion and appropriate boundary conditions are applied. The finite element simulation of milling hardened steel is built with different tilt angles. Milling force of simulation results are verified through experiments.Changes in the milling force with tilt angle are discussed, which can provide certain reference for cutting parameters optimization of milling process and 3D finite element modelling in milling.

Abstract: With the continuous progress and development of die industry, the traditional die processing has been unable to meet the current needs of society in the quality and quantity of production. Therefore, die manufacturing industry has improved its processing technology, and then high speed machining technology for dies emerges as the times require. The paper summarizes the elaborations of the characteristics of modern die manufacturing and the advantages of high speed cutting die, and the key technologies of high speed machining technology in die manufacturing are also introduced. Thus the paper illustrates that high speed machining technology is an important development direction of the current die processing.

Abstract: High speed sawing is an advanced machining technique for sawing of brittle materials with good component quality and high productivity. In the paper, sawing experiments were carried out to investigate the characteristics of sawing forces by altering many processing parameters in high speed sawing of quartz glass with a diamond blade. The sawing forces and force ratio were analyzed. The conclusions present that in the fixed material removal rate, the increasing of periphery speed can help to lower sawing forces and force ratio; sawing forces increase with material removal rate; in the high speed sawing, the effect of material removal rate on sawing forces is smaller than the one in the low speed.

Abstract: This paper presents a detailed analysis of chip morphology through an experimental study of high-speed milling of Ti-6Al-4V alloy with PCD tools. Milling tests were conducted for cutting speed range from 125 m/min to 2000 m/min with water-soluble cutting fluid. The collected chips were firstly examined with a digital cameras and the free surface of the chips was analyzed by a scanning electron microscope (SEM). Geographical parameters of chip morphologies were described in saw-tooth/lamella frequency on the free surface and chip width. Experimental results show that the variation of chips in high-speed end milling of Ti-6Al-4V alloy is as follows, long and straight-shaped → spiral-shaped → curly-shaped → irregular-shaped. The free surface of chips exhibits saw-tooth lamella structures. The lamella becomes clearer and more obvious at higher cutting speeds. Within the same measurement distance, there is a sharp decrease in the lamella number within same measuring range. This should be attributed to the enhancement of the thermal mechanical coupled field applied to the chip formation processes.

Abstract: A series of experiments was conducted in high speed dry turning of valve seat insert with PCBN cutters. The main tool wear surface morphology was observed by utilizing scanning electron microscopy and digital microscope. The experimental results indicate that the tool wear surface morphology is rake face wear, flank wear, chipping, flaking and breakage.