Qiao Ling Yuan

Form and Texture Control of Free-Form Surface Polishing

In this paper, a new type of flexible sub-size polishing tool, and an advanced polishing technique for free-form surface based on the new type of tool will be researched. The configuration of the flexible polishing tool and the method of controlling the multi-DOF precessions of the flexible polishing tool will be introduced. The rectilineal movement along X,Y, Z axis and flirts on two polar coordinates rotational axis of the polishing tool are used to control the form precision and the surface texture of polished surface. This polishing technique is enable to change continuously the polishing pressure and contact area and makes the flexible polishing tool well suited both to control the texture of work-piece surface and to control the form of work-piece surface. The influence functions the flexible polishing tool is near-Gaussian, symmetrical, and lacks the high spatial frequencies and center-zero of removal. The example of multi-DOF precessions polishing for optic spherical and aspherical will be introduced. The results show that the form, the size and the movement mode of the polishing tool will have important effect to polishing quality and multi-DOF precessions polishing can obtain better surface texture quality, form precision and higher polishing efficiency than traditional pole-down polishing for free-form surface.

Analytical Method for Softness Abrasive Flow Field Based on Low Reynolds K-ε Model

As it was difficult to solve the near wall characteristics of flow field in softness abrasive flow machining (SAFM) on mould structural surface, a method for simulation the flow characteristics based on the low Re number k-ε model was proposed in this paper. The U-shaped tube was used as specific simulation object. The motion law of particles and related parameters were calculated and the precision machining mechanism of SAFM was discussed. Simulation results show that the micro cutting of abrasive flow mainly appears as the transposition of cutting location influenced by the particle pressure, and as the variation of machining efficiency influenced by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time, it is supposed to work out the machining process according with the machining requirements. By tracking near-wall particles, it can be confirm that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement, so the feasibility of SAFM method can be reaffirmed.

Intelligent Tool Condition Monitoring System Based on Rough Sets and Mathematical Morphology

The image of cutting tools provides reliable information regarding the extent of tool wear. In this paper, we propose the theory of image processing based on rough sets and mathematical morphology to analyzing the flank faces which are chosen as our monitoring object. First, through plotting the appropriate subset, the rough sets filter is used to enhancement the image of tool wear. Then, the mathematical morphology theory is applied to process the translated binary image. Finally, tool condition monitoring is realized by measuring the area of tool wear. This paper gives the corresponding monitoring principal and proposes a new algorithm to process the cutting tool image. The algorithm is also flexible and fast enough to be implemented in real time for online tool wear or tool condition monitoring.

Application of Magnetic Abrasive in Gasbag Polishing

Application of magnetic abrasive to the field of finishing processes is increasingly popular and important. Magnetic abrasive finishing (MAF) is effective in precision machining of non-planar workpieces. To study the control of working abrasive morphology and the valid way to solve “incline effect” which is common in some industrial field, application of magnetic abrasive in gasbag polishing is presented. Besides, the polishing system is introduced, and the important factors which influence the magnetic abrasive polishing are studied. Then some tentative experiments are carried out to study its polishing effect. It is found that the difference of surface roughness value and material removal rate under different bevel angle is in small range, which indicates this approach is useful in solving “incline effect”. The work in this paper is also a good attempt for further study that polish precipitous surface of mould or other products.

Spinning- Inflated-Ballonet Polishing Tool and its Application in Curved Surface Polishing

In this paper, a novel spinning-inflated-ballonet polishing tool for curved surface of mould is proposed. The head of the tool is a spherical spinning-inflated-ballonet whose inner air pressure can be controlled on-line and the head surface is covered with a suitable polishing cloth. The head can be rotated in high speed driven by an electromotor or high pressure airflow and its rotating speed can be adjusted. The flexibility of the head, the polishing force in radial direction and the contact area between the head surface and the curved surface of the work-piece can be controlled by adjusting the feeding deepness and ballonet pressure of the tool. The structure and the polishing mechanism of the novel polishing tool are introduced. The application of robot polishing system based on the novel polishing tool also is discussed. Finally the polishing control strategy of curved surface is researched.

Magnetorheological Flexible Gasbag Polishing Technique

Combining the advantages of rheological behavior of magnetorheological fluid (MRF) and flexibility adjustability of rubber gasbag, a magnetorheological flexible gasbag polishing technique applied to free-form mould is proposed. With the development of robotic gasbag polishing technique, the flexibility of rubber gasbag can be adjusted by three methods of changing its internal pressure controlled through a pressure control unit, its own material property and structural parameter, and the rheological behavior of MRF inside of it in response to the application of an alterable magnetic field. Effect of rheological behavior to the flexibility of rubber gasbag and surface quality of mould is the single most important focus in this paper. The magnetorheological flexible gasbag polishing system is established and rheological behavior of MRF with magnetic field is described. Through polishing experiment focusing on the relationship between the surface roughness and current around electromagnetic coil, it can be obtained that magnetorheological flexible gasbag polishing technique is effective to improve surface quality when increasing current around coil in certain extent.

Dynamic Numerical Simulation of Mould Free-Form Curved Surface Gasbag Polishing

Polishing is an important technics processing in order to obtain the high quality surface of mould in industry mould manufacture. For the moment, polishing of the free-form curved surfaces of mould is performed by manpower. So it is important to research gasbag polishing technology. This paper has been developed dynamic numerical simulation for gasbag polishing process based on the new type of polishing tools by FEM. On the material removal theory, influence of the shape of the structure of the gasbag, angular velocity and the air pressure inside the air gasbag on the campaign polishing process are explored. It can be used to provide technology support to establish polishing process database.

Study of the Removing Depth of the Polishing Surface Based on a Novel Spinning-Inflated-Ballonet Polishing Tool

In the field of the mold-curved free surface polishing, how to control the removing depth of the polishing surface exactly is one of the important problems to be solved. In this paper, a mould automatic polishing system that is developed on Motoman-NL20 robot is used to make theoretical analysis and experimental research on the removing depth of the polishing surface based on a novel Spinning-Inflated-ballonet Polishing tool for curved surface of mould. Firstly, FEM (finite element analysis) software is used to emulate three kinds of situation in the process of polishing, then the model of surface removing depth of SBCT polishing is established. At last, through the analysis and comparison, the result of emulation and experiment has a remarkable consistency which accords with the model established by formal theory. This indicates the correctness of the model.

Dynamic Characteristic Difference on Two Kinds of Broading Machine on the Similar Configuration

This paper focuses on the dynamics characteristic difference on the two kinds of broading machine, the workpiece moving and the cutting-tool moving. There is 0.002mm thickness of oil-film clearance between the mobile and immobile components of the broading machine. Hydraulic pressure derived from the driving oil cylinder drives the workpiece or cutting-tool moving, while the material on the workpiece is cutting. Cutting-tool of the machine is an external expand cutter with the groove for breaking the cutting waste, the manufacturing phase is a pulse impact cutting exciting applying on the broading machine correspondingly. On manufacturing, natural characteristic of the broading machine is approximately the pulse impulsion frequency of the machine;response amplitude of the lather is increasing manifesting. The study is focused on the dynamics characteristic of two kinds of broading machine, the difference is workpiece or cutter moving, to predict the manufacturing performance.

Numerical Investigation on the Micro-Slip along Friction Interfaces

Damping in built-up structures is often caused by energy dissipation or energy loss due to micro-slip along frictional interfaces interaction, which provides a beneficial damping mechanism and plays an important role in the dynamics vibration behavior of such structures, especially the contact stiffness and damping coefficient accounting for the kinematics joint. A detailed study the mechanics derived from the interaction interface between the different components has some embarrassment. And a careful study on the micro-slip phenomenon has been carried out using the finite element method. A classical joint configuration, the plane translation joint, has been used as the model problems. The focus of this paper is to evaluate the effect of dry friction coefficient, the external mechanics on the damping response of frictional joint interfaces interaction, to understand the evolution of the slip-stick regions along a joint interface during loading, and to quantify the amount of energy dissipation/loss during cyclic loading and its dependence on structural and loading parameters.