Di Zheng

The Effect of Polishing Tool Path on Polishing Parameters

The force-position decoupling technology based on Magnetorheological Fluid Torque Servo (MRT) can effectively solve the force-position coupling problem existed commonly in polishing processes. In the new polishing system, polishing force is not generated directly by the displacement of polishing tool, but provided by the MRT. Polishing path planning is another key point of the force-position decoupling technology. In this paper, a polishing path planning method was proposed, and the effect of polishing tool path on polishing parameters was analyzed. The law obtained will guide the uniform material removal of aspheric surfaces.

Study on Force Control in Abrasive Polishing of Aspheric Parts

Aspheric parts are attracting many researchers’ attention for their excellent optical properties. The commonly used manufacturing technology for aspheric parts are mainly based on dedicated high precision machines, resulting in high cost and restricted application fields. To polish this kind of parts on general CNC machine tools, however, the surface quality improvement is limited due to the problem of force-position coupling. In order to solve this issue, a force-position decoupling control method for abrasive polishing was studied, a corresponding comliant polishing tool system was developed, and the mathematical model of the tool system was established. In addition, a polishing force controller was designed, and the performance of the tool system was numerically simulated. Simulation results showed that the polishing tool system can effectively achieve the tasks of force-position decoupling and the stable control of the polishing force.

Effect of Shape and Size of Polishing Pad on Material Removal Characteristic

The objective of this paper is to investigate the effect of shape and size of polishing pad on the material removal characteristics in the NC polishing. The material removal model was established based on Preston equation. The law of the effect of shape and size of polishing pad on the model was simulated. Experiments were carried out. Results showed that both of the shape and size of polishing pads influence the shape of material removal curves, polishing efficiency, and surface roughness. The amount of removed material increases with the increasing of size of polishing pad.

Design of MRF-Damper-Based Experimental System for Steer-by-Wire Force Feedback Study

In order to meet the requirements of research on steer-by-wire force feedback, a MRF- damper-based experimental system was developed. In the paper, the necessity of the experimental system was analyzed, the general structure and hardware components were introduced. The design of the rotary MRF dampers was illuminated in detail. Experiments showed that the MRF-damper-based haptic system can be used for the study of automobile steer-by-wire system.

A Novel MRF-Based Torque Servo Device

In mechanical equipments or manufacturing processes, force control is definitely required to achieve desired performance or to ensure product quality. Aiming at this issue, this paper introduced an author-invented torque servo device that utilizes magnetorheological fluids (MRF) to provide a controllable torque. In the paper, the structure and working principle of the MRF-based torque servo device (MRT) were introduced, the constitutive model and the characteristics of the MRF were established and discussed. On the basis, the static and dynamic models of the MRT were both analytically and experimentally studied, and the control of the output torque of the MRT was demonstrated. As an example, the application of the MRT to the polishing of aspheric surfaces was presented in the end.

Influence Factor Analysis for Tension Control Based on MRF Damper

Tension control is widely used in industrial production. This paper gives one tension control method using MRF damper as the actuator. The principle of the tension generation is introduced. Through analysis and numerical simulation, the main influence factor of tension changing is obtained. The result of simulation shows that the influence factor of the tension includes the excitation electric current of the MRF damper, the radius of a wheel, rotate speed, the fluctuation of the rotate, etc. These factors present strongly nonlinearity. Through controlling the excitation electric current of MRF damper, the fluctuation of tension can be controlled to decrease.

Study on Effects of Input Rotational Speed on Output Torque of Magnetorheological Torque Servo

Magnetorheological fluid torque servo (MRT) is a novel torque generating and controlling device. It converts the rotational input of active shearing disc into the torque output of passive shearing disc by controlling the rheological property of the magnetorheological fluid. In this paper, the working principle of the MRT was introduced. The effects of the input rotational speed on the shear stress of the magnetorheological fluid and then the output torque were analyzed. The model describing the relationship of the output torque with respect to the rotational speed of the active shearing disc as well as to other parameters was established. A critical rotational speed was deduced. The factors affecting the critical speed were discussed, and an experiment was conducted to ascertain the validity of the theoretical analysis.

Kinetics Analysis and Simulations on Load Fork Mechanism in Forward-Type Stacker

It is frequently reported by customers that the lower-left and lower-right wheels in the load fork mechanism of a kind of forward-type stacker designed based on static strength analysis are abraded faster than expected. In this paper, we studied by means of kinetics analysis and simulations the forces applied on parts of the fork mechanism. The simulation results show that the maximum values of instantaneous forces during operations are much higher than those derived based static force analysis, and thus explained the reason of the above-mentioned abnormal abrasion. The results also mean that static force analysis is not suitable for part strength design. Instead, one shall adopt kinetics analysis to explore the instantaneous forces in design.

Experimental System Design of Tension Measure and Control Based on MRF Damper

In order to meet the requirements of research on tension control system based on magnetorheological fluid (MRF) damper, an experimental system of tension measurement and control was developed using an industrial personal computer as hardware control center and using VC software as development tool. By applying the sensing and measuring, computer signal processing, motor speed control, and smart material technologies, the system can achieve the tasks of automatic tension measure and the automatic control of the whole running process. The system has the functions of speed measurement and control, tension measurement and control, as well as power supply control. The experimental data can be displayed and stored in real time. The system has friendly man-machine interfaces. The system can be maintained and expanded easily. Experimental test shows that the system can be effectively used for the research of the tension control based on the MRF damper.

Optimization of Structural Parameter of Shape-Adaptive Tool for Compliant Polishing of Aspheric Parts

The tool position based on the general interpolation arithmetic will make sharp changes which bring a harmful influence to the mixed control of pose and position as well as the normal force in grinding process. In this paper, a new type of shape-adaptive tool is proposed for the common NC lathe. The effective of shape-adaptive and the stability of polishing force is studied utilizing the dynamic analysis software ADAMS, at the same time, the structural is optimized. The simulation outcome indicates that the tool could both adapt to the surface of workpiece and remove the influence brought by interpolation arithmetic.