Bang Yan Ye

Investigation into Influence of Cutting Fluid and Liquid Nitrogen on Machined Surface Residual Stress

This paper gives the details of turning experiments on AISI 1045 steel by using various cutting fluid and liquid nitrogen condition. Residual stress on machined surface is generated in rough machining and fine machining with different rounded cutting edge radius. The effects of cutting fluid and liquid nitrogen on residual stress state are obtained by compared with dry cutting. Experimental results show that cutting fluid and liquid nitrogen have influence on machined residual stressl and liquid nitrogen generates residual compressive stress in all specimens.

Heating Current Control in Electric Hot Machining Based on Conservation Law of Optimum Cutting Temperature

In this paper, we investigate the relationship of heating current in Electric Hot Machining with tool life, cutting parameters and machined surface roughness. Experimental results indicate that there is an optimal heating current in EMH in which the effect of hot machining is the best. A method of rapid determining the optimal heating current under various cutting conditions in EHM is proposed according to the conservation law of optimum cutting temperature. That is, for a certain combination of tool and workpiece, the heating current relative to optimal cutting temperature in different conditions can be found by changing heating current and measuring cutting temperature to meet the control object of temperature in EHM. The PID control principle and effect of computer monitoring system for realizing optimal heating current control in EHM is also introduced.

Experimental Effect of Cryogenic MQL Cutting 304 Stainless Steel

Cryogenic MQL is a kind of green machining technology of the combination of cryogenic air and minimal quantity lubrication (MQL). The aim of this research is to determine if the cryogenic MQL technique in turning with Cutting tool with internal cooling structure gives some advantages in terms of tool life, surface roughness and cutting chip breaking. This paper reports the results obtained from turning tests, at one feed rates (0.12mm/r) and one depth of cut (0.4mm) and different cutting speeds (43m/min, 108m/min, 217m/min), and the results obtained show that using cryogenic MQL had some advantages in terms of tool wear, surface roughness and cutting chip breaking compared to using dry cutting and cryogenic air cutting. And the results obtained show that when cryogenic MQL and cryogenic air cutting were applied to high speed cutting, they had more advantages.

Analysis on Forming Characteristics of Cup-Shaped Thin-Walled Inner Gear Spinning

Spin-forming is a new near net-shape forming process for cup-shaped thin-walled inner gear (CTIG). The CTIG spinning was investigated by numerical simulation and processing experiments. The results show that the compressive deformation along tangential direction on the internal surface of part leads to a reduction in root circle of spun part; and the local loading and friction work result in the nonuniform radial deformation on the external surface of spun part. For spin-forming of CTIG with a small number of teeth, the diameter reduction is feasible for improving the forming quality of tooth groove, while the nonuniform radial deformation would cause concaves on external surface of part. For spin-forming of CTIG with a large number of teeth, the diameter reduction is not conducive to removing the part from the mandrel.

Heating Current Control in Electric Hot Minipore Drilling Hard-to-Cut Material

The key point for improving efficiency of Electric Hot Machining (EHM) is to keep an optimal heating temperature in cutting process. This paper introduces the principle and system for realizing optimal heating current control, Electric Hot Machining is applied to minipore drill of hard-material, a method of rapid determining the optimal heating current under various cutting conditions in electric hot drilling is proposed based on the conservation law of optimum cutting temperature. For a certain combination of tool and workpiece, the heating current in different cutting conditions can be obtained by changing heating current and measuring the cutting temperature in electric hot drilling.

Study on Pre-Stress Hard Cutting of Bearing Races

The analysis on load characteristics and stress state of bearing races shows that the roll path and outside layer of a bearing race are the main part to bear the load, and that residual tensile stress is often found on workpiece surface. For the purpose of improving residual stress state on machined surface of a bearing race, a method of pre-stress hard cutting is put forward. In this paper, the principle of pre-stress cutting is introduced, and method of loading stress on bearing races, together with the calculation for pre-stress, is analyzed. A set of device with expanding mandrel for realizing the process is designed too and an experiment of pre-stress cutting is carried out on a lathe with PCBN tool. The experimental results show that, by using this method, we can get residual compressive stress on machined surface layer of a bearing race and increase the quality and contact fatigue life of bearing.

Influence of Machining Parameters and Pre-Stress on Residual Stress of Pre-Stress Hard Turning in 40Cr Steel

Machined residual stress is an important index in machining quality, and pre-stress cutting is a process which can increase the residual compressive stress on machined surfaces. This paper investigated the effect of machining parameters and pre-stress on residual stress of 40Cr steel by orthogonal experiment. The experiment results also showed that pre-stress could increase the residual compressive stress effectively, and it had obvious significance for residual stress than those significances of machining parameters; ap had more obvious affect on the residual stress than vc and f have, and residual compressive stress decreased with the increase of ap, vc and f. A prediction formula for residual stress of pre-stress hard turning was obtained from the experiment results and it was verified reliable by other experiment.

Experimental Study on Pre-Stress Hard Cutting of Aero-Screw and its Machined Surface Residual Stress State

Pre-stress Hard Cutting, known as a new machining technology, is the combination of hard cutting and pre-stress cutting. Some reports show pre-stress machining can improve residual stress state of machined surface and prolong fatigue life of mechanical part, such as drive shaft, bearing and engine vane etc. Based on the principle of this technology, this paper take aero-screw shaft machining as object, investigated the pre-stress loading method, experimental device and implementation process of pre-stress hard cutting. Experiment is carried out for aero-screw shaft with PCBN tool, cutting force, machined surface residual stress state and distribution are measured. The experimental results show that by using this method, residual compressive stress is got on machined surface and good surface finish is gained, hence it can control machined surface residual stress state actively and improve the fatigue life of aero-screw shaft..

Study on Pre-Stress Cutting of Bearing Race and Its Machined Surface State

Theoretical analysis and experiments on bearing race show that a suitable residual compressive stress on roll path of bearing race can prolong its contact fatigue life. However, residual tensile stress is often found on workpiece surface of bearing race. To actively control the residual stress state and improve fatigue life of bearing part, a new method of pre-stress hard cutting is applied. In this paper, the principle of pre-stress hard cutting for bearing race is introduced as well as the experiments on it. In the experiments, residual stress, hardness and roughness of machined surface are measured and analyzed. Moreover, micro-topography and texture characteristics of machined surface are investigated and experimental results are compared with that by grinding. It is found that we can get residual compressive stress and fine quality on machined surface of bearing race by pre-stress hard cutting and increase its productivity as well.

Vibration Characteristic of Violin Bowstring and Experimental Research on Helmholtz Motion of String

The sound source of violin is string vibration. By the stick–slip friction action between bow and string of violin, string and bridge form a complicated vibration system. The interaction mechanism of bowstring is very intricacy. In this paper, through theoretical analysis and experiment, the vibration behavior of violin string is investigated. We measured the vibration images of bowing and plucking violin string on a high-speed photography optical platform and got two different character of string vibration, including vibration displacement, velocity and space trajectory of the mark point on string. By comparing the displacement curves of the different points among on string, the variety of the ratio of positive process time to negative one of vibration sawtooth waveform are studied, and also the formation process of string vibration enveloping curve. On this basis, the Helmholtz motion of string vibration which is presented at 1862 is studied.