Hou Jun Qi

Finite Element Simulation Study of Cutting Process for Large Thin-Wall Part of Aluminum Alloy

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.

Study on the Laser Shock Processing with Square Spot of Titanium Alloy Based on ABAQUS

Laser shock processing is a new kind of technology to improve the physical and mechanical properties of the metal surface. It uses the high-amplitude stress wave produced by the interaction of short-pulse laser and material, to make the material produce the compressive residual stress and refinement internal structure, and lead to the improved hardness and strength of material. In this paper, the simulation of laser shocking process with square spot of Titanium alloy plate was carried out through ABAQUS. The influences of the shock time, laser energy, plate thickness and spot size on the strengthening are investigated from the view of residual stress. The results show that: There are the compression residual stress in the workpiece surface after laser shcok processing, and its amplitude is about 300-400Mpa. With the increase of shock time, the surface residual stress increases, the area and depth of strengthening zone also increase. The strengthening area becomes a circular, while the distribution of residual stress becomes unhomogeneous. The surface residual stress increases as the laser energy increasing, but the amplitude is smaller. The plate thickness does not affect the amplitude of the surface residual stress. When the shock pressure is constant, surface residual stress does not change with the spot size. However, if the laser energy is constant, due to the shock pressure will decrease with the increase of spot size. Therefore, there should be an optimized spot size when the strengthening effectiveness and efficiency are both considered.

Experiment Study of Serrated Chip and Surface Roughness of High Speed Cutting of Ti6Al4V

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.

Finite Analysis of Cutting Temperature with Internal Lubricating Tool

The objective of this work is to model the cutting temperature generated during dry turning with micro-graphite internal lubricating tool. Dry cutting FEM were carried out with these micro-graphite internal lubricating tool and conventional YG8 tool based ABAQUS. The machining performance was assessed in terms of the cutting temperature. Results show that the cutting temperature with the micro-graphite internal lubricating textured tools was reduced compared to the conventional tool.

Finite Element Simulation on High Speed Cutting of Hardened 45 Steel Based on ABAQUS

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.

Prediction of Adiabatic Shear Critical Cutting Conditions of hardened AISI 1045 Steel with Different Hardness

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.

Method of Tool Path Optimization in Impeller NC Machining Based on Configuration Space Theory

The impeller as the key part of aircraft engine components, and the impeller blade surface is complex, and it is a typical complex difficult machining parts. Five-axis NC machining is the important means to realize sculptured curved surface parts machined with high quality and efficiency. In this paper, in view of the interference problems occurred in the process of impeller five-axis NC machining tool path generating, the configuration space method is proposed to tackle the problem of interference, cutter location point as constraint conditions, the cutter position is described by using two angle parameters, optimization of cutter position, tool path generated without interference, improve the impeller machining quality and production efficiency. Finally, as a case study of a certain type of impeller, it makes arithmetic realization combining with MATLAB.

Experimental Study of Serrated Chip in High Speed Cutting

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.

Experiment Study of Adiabatic Shear Critical Conditions in Orthogonal Cutting of Fe-36Ni Invar Alloy

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.

Study on Constitutive Relationship of Fe-36Ni Invar Alloy

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.