Papers by Author: Li Gang Cai

Abstract: Ink is one of the important material in printing process, its features, to a great extent, decide the printing quality, and ink viscosity is one of the main parameters, the value of the ink viscosity directly affects the quality of printing. In the case of other conditions are determined, the main factor of influencing the ink viscosity is temperature. In this paper, by using the Workbench CFX fluid simulation software, the ink temperature field of two extrusion ink rollers in printing press is analyzed by numerical simulation , the influence of the ink roller speed on ink temperature and the influence of ink roller thermal conductivity on the ink temperature are analyzed,.

Abstract: Ultrasonic elliptical vibration turning (UEVT) is an advanced machining technique for difficult-to-cut materials, in which with frequency in excess of 20 KHz is superimposed on the cutting tools movement. In order to analyze the effect of vibration frequency on cutting forces and cutting temperature, finite element models of ultrasonic elliptical vibration turning were developed. The cutting forces and the distribution of the temperature on workpiece and cutting tool were predicted. It is observed that the cutting forces and cutting temperature decrease with the increase of the vibration frequency.

Abstract: In order to achieve the remanufacturers and utility extension of the old heavy-duty machine tool, an adaptable design method of the heavy machine tool that oriented to the green remanufacturing is proposed in this paper. The guiding ideology of the adaptable design is integrated into the green design and product development. The present status of research at home and abroad is summarized, and then the existing problems are analyzed. Axiomatic design is introduced to be the research principal line and the four design domains are extended to five ones including regeneration domain. By full analysis, the three future research directions including the adaptable modular design, the adaptable platform design and the adaptable interface design of the heavy-duty machine tool, are proactively introduced.

Abstract: The double ball bar is widely used because it can quickly, easily and cost-effectively detect and evaluate the accuracy of CNC machine tools. But since the error recognition algorithm based on the double ball bar ignores the quadratic item, its recognition accuracy would be reduced. In this paper, an improved CNC verticality error and position error identification formula, combined with the machine tool error model to deduce a new error recognition model of double ball bar measurement is proposed. It can be drawn that the accuracy of the model are better than the existing methods because it keeps the second item in the derivation process of the model.

Abstract: This paper established a general mathematical modeling method based on stress analysis of the angular contact ball bearing under high rotation speed. The influence of the centrifugal force and gyroscopic moment generated in the rotation process is taken into account in this mathematical model. This paper conducted in-depth research for these aspects: the stiffness characteristics of angular contact ball bearings under different load conditions and different rotational speed, internal contact deformation and the change of bearing parameters.

Abstract: This article investigates the effects of bearing configuration on the spindle dynamic characteristics. First, an analytical model of spindle is proposed and the bearing sets radial stiffness is calculated. Second, the spindle analytical model is developed to perform modal analysis and harmonic response analysis with ANSYS, and then obtain the natural frequency and FRF under different bearing configurations. The result suggests that bearing configuration has little effect on the natural frequency of spindle system and the FRF amplitude corresponding to the 1^st natural frequency under back to back configuration or face to face configuration is relatively small. Finally, the proposed model is validated by modal experiment.

Abstract: The hard roller and soft roller are alternately arranged in the inking system of offset press. The ink vibrator is a hard roller which transmits the motion to the ink distributing roller. In order to analyze the motion mechanism of the ink roller, a model of an ink distributing roller and an ink vibrator is built up by using the software ANSYS. After the simulation of the motion, the force on the contact area of the ink distributing roller and the rotation speed of both rollers are analyzed. The result is that the ink distributing roller rotates with tangential force on the contact area and this force increases together with the rotation speed. When the two rollers rotate, the tangential elastic deformation is caused by the tangential force on contact area, and the radial deformation of the ink distributing roller is caused by the pressure. It leads to a relative sliding of the two rollers, which is mainly influenced by the rotation speed of ink vibrator and the radial deformation of ink distributing roller. Meanwhile, to verify the accuracy of the analysis, the rotation speed of the two rollers and the deformation of the ink distributing roller have been measured on a printability tester and then compared with the results of simulation. The analysis of the motion mechanism is very important to the study of printing color quality control.

Abstract: The normal static stiffness plays an important role in the whole connection of bolted joints. Both the design and the connection quality are depended on the normal static stiffness. But the nonlinear characteristics of its normal static stiffness is not well explained. An experimental test is developed herein to clarify the influence of the jointed surfaces. And the nonlinear effect of jointed surfaces of bolted members has been separated from the total stiffness. The nonlinear relation between the extensile force and the joints’ stiffness in the jointed surfaces under different preloads has been extracted through the experiment.

Abstract: According to the characteristics of constant flow and closed hydrostatic rotary table used in heavy duty CNC machine, in order to consider the interaction between structural deformation of worktable and the supporting force of oil pads, an iteration method between hydrostatic theory calculation and finite element method (FEM) is used to get the real supporting force of each oil pad at different carrying state. The result is compared with the situation which is not considering the deformation of worktable and the difference between them can be used to guide the design of hydrostatic oil pads. The optimal radius of supporting point of work piece is also achieved using this method, which can provide theory basis for supporting point distribution of heavy work piece.

Abstract: This paper established the finite element model of a hydrostatic guideway. Based on the thermal characteristic simulation analysis, the temperature field and thermal deformation of the guideway were obtained. The analysis results show that the oil film temperature increment will cause thermal deformation of the guideway and processing errors. The errors will influence the machining accuracy of machine tools. The analysis results provide certain theory basis for the research on the above influence. And then the results also give certain reference for the research on the thermal error compensation of machine tools.