Papers by Author: Hou Jun Qi

Abstract: Under the condition of cutting speed 10-300m/min, rake angle -10°、0°、10°and cutting depths 0.05mm、0.1mm and 0.2mm, the experiment study of adiabatic shear serrated chip and surface roughness are carried out. The influence of cutting condition on serrated chip is analyzed through the metallographic observation of obtained chip. By the measurement of finished surface, the influenc of cutting condition and adiabatic shear on surface roughness is also investigated. The rusults show that the reason lead to serrated chip in high speed cutting of Ti6Al4V is adiabatic shear, not the periodic fracture.The adiabatic shear serrated chip is easier appear and the degree of segment is more large under the condition of higher cutting speed, larger cutting depth and smaller rake angle. The surface roughness is smaller when the cutting speed is higher, cutting depth is larger, and rake angle is smaller.

Abstract: A method for building the constitutive relationship based on the J-C model and hardness is presented through considering the influence of hardness on the yield strength and the tensile strength. A constitutive relationship of hardened AISI 1045 is built by this method and the adiabatic shear critical cutting conditions of three kinds of hardness AISI 1045 steel are prediction through a model building by the linear pertubation analysis which considering the influence of compression stress of the primary shear zone, the cutting conditions and the constitutive relationship. For proving the prediction results, some orthogonal cutting experiments are performed to get the critical cutting conditions of adiabatic shear. The comparison shows that the prediction results are consistent with that of experiments.

Abstract: For the high speed cutting process of hardened 45 steel (45HRC), a finite element simulation of cutting deformation, cutting force and cutting temperature is finished with the large general finite element software ABAQUS. Through the building of geometry model, material model and heat conduction model, also the determination of boundary conditions, separation rule and friction condition, a thermal mechanical coupling finite element model of high speed cutting for hardened 45 steel is built. The serrated chip, cutting force and cutting temperature can be predicted. The comparison of experiment and simulation shows the validity of the model. The influence of cutting parameters on cutting process is investigated by the simulation under different cutting depthes and rake angles. The results show that as the increase of rake angle, the segment degree, cutting force and cutting temperature decrease. But the segment degree, also the cutting force and cutting temperature increase with the increase of cutting depth. This study is useful for the selection of cutting parameters of hardened steel.

Abstract: A finite element simulation study of cutting process and whole part deformation of a large thin-wall aluminum alloy part used in aerospace is carried out by ABAQUS. The geometry model, material model and heat conduction model are built. The friction conditions and boundary constraints are determined. The whole process of chip generation is simulated and the distribution of strain, stress, cutting temperature and are given. The chip formation and the cutting force are also predicted. Based on the prediction results, the deformation of whole part is predicted. This study establishes the foundation of selection and optimization of cutting parameters and deformation compensation for this kind of large thin-wall parts.

Abstract: In this paper, some high speed cutting experiments of hardened 45 steel are carried out. The effects of cutting parameters on the width and space of adiabatic shear band, the frequency and degree of sawtooth are investigated by metallographic observation and theoretical calculation. The results show that the space of adiabatic shear band decreases with the increase of cutting speed and rake angle, but increases with the increase of cutting depth. The width of adiabatic shear band decreases with the increase of cutting speed and cutting depth, however, increases with the increase of rake angle. The frequency of sawtooth increases with the increases of cutting speed, decreases with the increase of rake angle, and has no obvious relationship with cutting depth. The degree of sawtooth increases with the increase of cutting speed and cutting depth, but decreases with the increase of rake angle.

Abstract: This paper deals with an investigation of surface integrity of Ti6Al4V alloy with zirconia alumina and SiC belts. The experiments were conducted under dry grinding environments in milling machine XS5040 equipped with belt grinding device. Microcosmic geometry parameters were measured with TALYSURF5 instrument, the surface morphology machined workpiece and the phase structure was analyzed using 3D viewer microscope, surface hardness for ground surface was measured by HXS-1000A instrument. The results show that surface quality maintain better level during a long period, the grinding affected zone was small(≤15μm), zirconia alumina belt has excellent performance than SiC belt during dry grinding Ti6Al4V alloy.

Abstract: This paper was dedicated to elucidate an investigation of abrasive wear and surface topography of Titanium alloy TA15 on dry grinding with zirconia alumina belt. In the investigation, experiments were performed on milling machine XS5040 equipped with assembled belt grinding device. The wear abrasive, surface morphology of machined belt in different phase were analyzed using 3D viewer microscope. The results show that the wear of belt abrasive is mainly steady attritions wear since zirconia alumina belt was stable on dry grinding. At higher grinding force, the abrasive was found to undergo dislodging prior to being gradually worn. So zirconia alumina belt has excellent performance in the dry grinding titanium alloy.

Abstract: Orthogonal cutting experiments of Fe-36Ni invar alloy are performed. The change of chip morphology with cutting conditions are investigated through metallurgical observation, and the critical cutting speed of adiabatic shear for Fe-36Ni invar alloy at different cutting depths and rake angles are given. In addition, the characteristic of chip deformation before the occurrence of adiabatic shear is also analyzed. The results show that the critical cutting speed decreases with the increase of cutting depth and hardness, but increases with the increase of rake angle. The deformation coefficient tends to a constant value with the increase of cutting speed.

Abstract: By electronic universal testing machine and Split Hopkinson Pressure Bar, the mechanical properties data of Fe-36Ni invar alloy are gained at a range of temperature from 20°C to 800°C and strain rate from 10^-3 /s to 10⁴/s. An improved Johnson-Cook model is presented to describe the mechanical behavior of Fe-36Ni invar alloy at high temperature and high strain rate, and verified by experimental results.