Papers by Author: Chun Gen Shen

Abstract: On the basis of modal analysis theory, a free modal test and a work modal test of the HSK tool holder and thin-disk cutters with the vibration measuring method were carried out. The modal parameters such as inherent frequency, damping ratio and modal shapes were gained. These modal parameters were compared with modal parameters, which were gained with the finite element method. The results verified whether the construction of the finite element modal was reasonable or not, and provided technical help for exploring the dynamic characteristics and structural optimization of HSK tool system, making the full use of HSK tool holder in high- speed machining.

Abstract: A new finite element model of BIG-PLUS tooling system are made, the BIG-PLUS tool holder and spindle deformation owing to centrifugal force generated by displacement, as well as different speed and clamping force of the radial displacement are analyzed and simulated. The results show that the radial clearance and deformation between spindle and tool holder can expand as the rotating speed increases, enhancing the clamping force and the shank of the spindle positioning accuracy and reliability of connection.

Abstract: In this study, an integrated methodology combining computational modal analysis, experimental modal analysis, and computational dynamic analysis was developed to investigate unbalancing dynamic responses of high speed machining tool systems. A linear-elasticity formulation based on the finite element method (FEM) was employed to compute the natural frequencies and obtain the corresponding modal shapes. Experimental modal analysis was then performed to verify the natural frequencies. After the validation, the FEM model was further modified to predict the dynamic responses, with an HSK (a Germany abbreviation of Hohl Schaft Kegel) tool system as a model system. The results indicated that, by validating the computed natural frequencies with experimental ones, an effective simulation model can be established for predicting complex dynamic response of high speed machining tool systems.

Abstract: In this work, the prediction and analysis of cutting forces in precision turning operations is presented. The model of cutting forces is based on the oblique cutting force model which was rebuilt by two coordinate conversions from the orthogonal cutting model. Then the cutting field in precision turning was divided into two fields which are characterized as curve change and linear change on cutter edge and they were modeled respectively. Cutting field of cutter nose was modeled by differential method and its cutting force distribution is predicted by the proposed method. The predicted results for the cutting forces are in agreement with the experimental results under a variety of operation variables, including changes in the depths of cut and in the feedrate.

Abstract: In Minimum Quantity Lubrication machining, cutting fluid is provided as mist. Mist with different velocity and diameter may lead to different cooling, lubrication effect and cutting quality. Thus, cutting quality is highly influenced by spray characteristics in MQL machining. In this study, the mathematics model of mist flow was set up first. Then spray characteristics were tested by a 3-Dimensional Particle Dynamic Analyzer. In order to study the influence of spray characteristics on cutting quality, precision turning of 45 steel was performed by a CNC Super Precision Machine Tool. The results indicate that the lowest surface roughness was obtained by supplying more cutting fluid at proper position for spraying distance of 20mm.

Abstract: This paper investigates the effect of spindle clamping force on the static and dynamic characteristics of the spindle-tooling system through measuring the frequency response function of the tool end point in variable spindle clamping force. The research shows that the limited static stiffness increases accordingly and normal static stiffness changes little as the spindle champing force increases. The high spindle clamping force leads to reduce the modal damping of the spindle-tooling system while the natural frequency varies slight. The analyses of process stability indicates that the low spindle clamping force can improves the process stability because of the higher damping in some clamping force range.

Abstract: Based on the orthogonal cutting experiments, the two side direction burrs in metal cutting were studied. In this study, the cutting model of two side direction burr formation and translation is established with plane stress-strain theory. The main laws of formation and change of burr in size and type in orthogonal cutting are revealed, and it is confirmed by experiment results, which first realizes control of the forming and change of the two side direction burr in metal cutting operation.

Abstract: The stiffness of the HSK tool system directly influences the efficiency and the quality of high-speed machining. Based on the mechanics of materials and finite element method, theoretical analysis and digital simulation are done with the stiffness of the HSK tool system. An equation to calculate the deformation angle of the HSK shank is proposed. The basic change law of the stiffness of the HSK tool system is shown and it offers theoretical base for properly applying the HSK tool system to maximize benefit. It is important in theory and application area to develop new-style tool system with our own intellectual property.