In this paper, we propose a new ultra-high-precision magnetic abrasive finishing method for wire material which is considered to be difficult with the existing finishing process. The processing method uses a rotating magnetic field system with unbonded magnetic abrasive type. It is believed that this process can efficiently perform the ultra-high-precision finishing for producing a smooth surface finish and removing a diameter of wire material. For such a processing improvement, the following parameters are considered; rotational speed of rotating magnetic field, vibration frequency of wire material, and unbonded magnetic abrasive grain size. In order to evaluate the performance of the new finishing process for the wire material, the American Iron and Steel Institute (AISI) 1085 steel wire was used as the wire workpiece. The experimental results showed that the original surface roughness of AISI 1085 steel wire was enhanced from 0.25 µm to 0.02 µm for 60 s at 800 rpm of rotational speed. Also, the performance of the removed diameter was excellent. As the result, a new ultra-high-precision magnetic abrasive finishing using a rotating magnetic field with unbonded magnetic abrasive type could be successfully adopted for improving the surface roughness and removing the diameter of AISI 1085 steel wire material.

This paper describes the implementation of general multibody system dynamics on Scissor lift Mechanism (i.e. four bar parallel mechanism) within a bond graph modeling framework. Scissor lifting mechanism is the first choice for automobiles and industries for elevation work. The system has a one degree of freedom. There are several procedures for deriving dynamic equations of rigid bodies in classical mechanics (i.e. Classic Newton-D'Alembert, NewtonEuler, Lagrange, Hamilton, kanes to name a few). But these are labor-intensive for large and complicated systems thereby error prone. Here the multibody dynamics model of the mechanism is developed in bond graph formalism because it offers flexibility for modeling of closed loop kinematic systems without any causal conflicts and control laws can be included. In this work, the mechanism is modeled and simulated in order to evaluate several application-specific requirements such as dynamics, position accuracy etc. The proposed multibody dynamics model of the mechanism offers an accurate and fast method to analyze the dynamics of the mechanism knowing that there is no such work available for scissor lifts. The simulation gives a clear idea about motor torque sizing for different link lengths of the mechanism over a linear displacement.

The ultra-high-speed magnetic abrasive machining (UHSMAM) process is a surface improvement technique, which has been widely used to minimize the surface accuracy and change the precision morphology of difficult-to-machine materials. Surface integrity plays an important role in the machining process, because it is used to evaluate the high stress and the loaded components on the machined surface. It is important to evaluate the plastically deformed layers in ultra-precision machining surface of material. However, the usual plastic strains in the ultra-precision machining surface are significantly difficult to consider. In this paper, an ultra-high-speed magnetic abrasive machining technique is used to improve the surface accuracy and dimensional accuracy of an AISI 304 bars. Additionally, the subsequent recrystallizations technique is used for measuring the plastic strain on machined surface of AISI 304 bars. The purpose of this paper is to evaluate the effects of an UHSMAM process on the plastic strains and the strain energy of the machined surface, and to evaluate the residual strain in the plastic deformation of AISI 304 bars materials by analyzing a plastically deformed layer. The results showed that the plastic strain of the material did not change after machined by an UHSMAM process. Based on the results, an UHSMAM process could significantly improve the surface roughness, micro-diameter, and removal weight of AISI 304 bars effectively. The surface roughness Ra of AISI 304 bars was improved from 0.32 µm to 0.03 µm for 40 s of machining time at 80,000 rpm of workpiece revolution speed.

No abstract

This work focuses on the bond graph modelling method and its application on multi-body system, especially on the five-bar parallel robot. Five-bar parallel robot is comprised of four arms, two revolute actuators and five revolute joints. This paper adopts five-bar parallel robot in symmetric configuration as simulation object. As it will be used as a pickup and placing machine, its workspace is fixed on Cartesian coordinate. The relationship between the two rotating angles and end effector’s desire position is built by inverse kinematics. Bond graph is used to describe moment, torque, velocity, angle relationships. In this project, the dynamic performances between arms, motors at robot basement and end effector will be researched. In this paper, an investigation about how to use bond graph to model DC (direct current) servo motor and an integrated motion control system is carried out. During a typical end effector point-point displacement, the torque change between arms is plotted. Finally, 3-D animation experiment is conducted. Experiment results show that bond graph can simulate robot dynamics performance without having to make a large number of equations. It is able to simulate and solve five-bar kinematics problem in the process.