Development of a new magnetic abrasive finishing process with renewable abrasive particles using the circulatory system

In order to improve the finishing efficiency of the Magnetic Abrasive Finishing process, we proposed a new MAF process with renewable abrasive particles using compound magnetic finishing fluid circulatory system in this paper. This new finishing process has a circulating system that uses a conveyor belt to renew the mixed abrasive particles. This not only maintains the stability of the finishing but also ensures that the processing does not need to be interrupted. In this study, we investigated the magnetic field distribution, finishing force, and finishing behavior of the processing area. Furthermore, we designed experimental device to finish the sus304 stainless steel plate, to verify the feasibility of this process and understand its characteristics through processing experiments. Moreover, the influence of important process parameters, including magnetic particles, abrasive particles, conveyor belt line speed and working gap, on the surface quality of the workpiece is studied through the experiment. The experimental results indicate that the present process can achieve stable processing of the material surface without interruption, and the surface roughness of the sus304 stainless steel plate has been improved from 273 nm to 23 nm through this process.     

Large-area profile measurement of sinusoidal freeform surfaces using a new prototype scanning tunneling microscopy

This paper presents large-area profile measurement of ultra-precision diamond turned sinusoidal surfaces by using a specially developed scanning tunneling microscopy (STM). The new prototype of STM system employs a long stroke PZT servo actuator as the Z-directional scanner, an integrated capacitance displacement sensor to accurately measure the Z-directional profile height, a motorized stage with long traveling stroke for carrying out large-area scanning. A simple method for self-calibration of the inevitable sample tilt is proposed in order to achieve large-area measurement without tip-crashing or losing of tip-sample interaction. Several types of ultra-precision machined sinusoidal freeform surfaces with different geometrical parameters are measured by the new STM system over large scanning areas at the scale of millimeters. Specially, a sinusoidal surface with peak-valley amplitude of 22 μm and periodical wavelength of 550 μm is successfully measured and imaged by the STM system. The measurement repeatability error, repeatability standard deviation and measured profile deviation are also evaluated. It is confirmed that the new STM system is capable of carrying out large-area as well as large-amplitude measurement of the ultra-precision machined sinusoidal surfaces.     

Towards a rational surface profile characterization system

Approaches to surface profile characterization are first discussed and the superiority of a suitable statistical approach based on a set of ‘primary’ parameters suggested. The selection of such a set is considered with reference to recent publications on parameter inter-relationships and approaches to spatial characterization of profiles containing both random and periodic components, and a primary parameter set then proposed. The estimation of other surface finish parameters from those in the primary set is considered and illustrated for profiles from a number of machining processes.     

Measurement of coated abrasive surfaces

The measurement and characterisation of coated abrasive surfaces are reported. Four different techniques were used with the emphasis on simplicity, sensitivity and, most important, repeatability. As a process control technique stylus measurement with simple statistical analysis was found to satisfy most of the necessary requirements for “shop floor” use.     

High-precision numerically-controlled measuring system for cylindrical surfaces

An instrument has been developed which can measure the roundness, straightness and surface texture of cylindrical surfaces whose cross-sections are either circular or deviate only slightly from a circle. The precision of the measuring system arises from ensuring the accuracy of relative rotational and axial motions and from the use of a stable displacement transducer with a high resolving power. Cylindrical scans of the surface can be obtained with a high degree of accuracy.     

Development of a novel profile measurement system for actively planed surfaces

The importance of a reliable and robust surface profile measurement system in the inspection of surface finish is beyond any doubt. For years, visual inspection has been employed in industries to determine the quality of surface finish. Since, in most cases, it fails to ensure a consistent minimum standard of finish quality, mechanical stylus based measurement systems have successfully taken over from human inspection. However, in recent years, the trend is to explore other techniques for conducting the surface profile measurements. Non-contact optical methods have emerged as one of the leading candidates. A target application concerning the surface quality of wooden products requires the use of non-contact techniques to avoid surface damage. This paper deals with a non-contact optical surface profile measurement system based on the pickup of a commercially available DVD player. Significant cost reduction and seamless integration of the sensor into a manufacturing process line may be achieved with the proposed method. The performance of this DVD profilometer with samples of Delrin nylon and hardwood has been analyzed and discussed in this paper. It has been shown that the measurement results show good correlation with the benchmarks obtained with the help of a leading commercial profilometer, the Talysurf.     

Optical system for measuring the profiles of super-smooth surfaces

The design of a common-path polarimetric interferometer system, developed primarily for measuring the profiles of ‘super-smooth’ surfaces, is described and measured comparisons with a mechanical stylus technique are discussed. The instrument has a sensitivity to changes in surface height of better than 0.1 nm and is capable of a lateral resolution of 1 μm with a helium-neon laser light source.     

Study of an internal magnetic abrasive finishing using a pole rotation system: Discussion of the characteristic abrasive behavior

An internal magnetic abrasive finishing process using a pole rotation system was proposed to produce highly finished inner surfaces of workpieces used in critical applications. Previous research found that the process incorporating one of the characteristic behaviors of the abrasive, the jumbling of the abrasive, results in aggressive contact of the abrasive against the inner surface, disturbing the smooth surface finish. The aim of this paper, therefore, is to characterize the in-process abrasive behavior against the surface and its effects on the finishing characteristics and to describe the finishing mechanism. The magnetic force acting on the magnetic abrasive, controlled by the field at the finishing area, is considered the primary influence on the abrasive behavior against the inner surface of the workpiece. This study examines the relationships between the magnetic field, the force on the abrasive, and the abrasive behavior. The surface roughness and material removal measurements resulting from finishing experiments demonstrate the effects of the abrasive behavior on the surface modifications. This paper also proposes a method to monitor the in-process abrasive behavior to facilitate processing.     

Finishing of structured surfaces by abrasive polishing

A new polishing process for the finishing of structured optical elements was introduced by the authors. Abrasive polishing using pin type and wheel type polishing tools made of polyamide was applied to improve the surface roughness of structured molds exhibiting fly-cut and precision ground V-grooves. Surface roughness of abrasive polished sides of V-grooves was found to be about 5 nm Ra. Furthermore, material removal rates were determined according to Preston's equation resulting in increasing removal rates with increasing polishing pressure and relative velocity. Material removal in abrasive polishing of structured surfaces was observed to be caused mainly by two-body abrasion but also by three-body abrasion, depending on relative velocity and polishing pressure. Tribological investigations showed that in abrasive polishing of structures mainly micro-ploughing and less micro-cutting occurs.     

Investigation of error separation for three dimensional profile rotary measuring system

High precision 3D profile rotary measuring systems for large diameter workpieces are urgently needed in precision engineering. Error separation is critical for improving the accuracy of the system. In order to obtain higher accuracy for 3D profile rotary measuring systems, the random and systematic errors are analyzed and separated in this paper. In the measuring system, roll and pitch caused by the probe tilt violate the Abbe principle. Roll is removed by using two probes and pitch is separated by the interferometer method. The radial run-out and the perpendicularity error between the probe and the spindle axis are compensated by a two-probe-two-step method carried out on a standard hemisphere artifact. As the form error of the artifact is mixed with the perpendicularity error, the least-squares method is applied to fit the hemisphere and work out the perpendicularity error and the profile error of the hemisphere. Finally, numerical validation is presented using Matlab program to demonstrate the effectiveness and correctness of the proposed method.     

模具结构化表面SAF精密光整技术

针对模具结构化表面难以采用传统抛光工具实现精密光整加工的问题,提出了一种基于软性磨粒流(SAF)的模具结构化表面无工具精密加工新技术.该技术通过约束模块与结构化表面组合构成特定形状的磨粒流流道,利用SAF在流道中的湍流流动使磨粒对结构化表面进行微力微量切削,进而实现光整加工.介绍了SAF加工技术原理、SAF流体力学特征...     

新型光电式转矩转速测量系统的研究

基于8051单片机,利用光反射原理和光电元件的响应特性,提出了一种在高速运转条件下测量转速转矩的新型光电式测量系统.阐述了其测量原理和主要硬件电路设计,具有结构简单、测量准确、使用方便等特点.     

镜面物体三维测量系统中两显示屏的平行正对校正

针对镜面物体三维测量系统中两显示屏无法精确平行正对的问题,提出了一种在镜面物体三维测量系统中通过软件产生变形条纹等效两显示屏精确平行正对的方法。该方法首先采用机器视觉技术标定两显示屏的外参。然后基于所标定的外参,利用软件编程产生等效两显示屏平行正对的变形条纹,变形条纹通过半透半反镜后所成的像在相机坐标系内呈现前后精确平行正对的关系。最后,利用对应两个显示屏上的变形条纹计算相应位置相位的差值,并通过均方根误差定量评定所提出的方法。实验结果表明,所提出的方法能将水平方向的均方根误差缩减为原来的24.21%,竖直方向的均方根误差缩减为原来的8.15%,从而提高三维测量系统的精度。     

Three-dimensional filtering of engineering surfaces using envelope system

With the advent of cheap and powerful computers, three-dimensional evaluation of surfaces is possible. This article deals with the development of a computational method for three-dimensional filtering of surface using the envelope system (E-System, a dialation using a sphere) concept. The shape of the envelope surface is dependent only on the prominent peak points on the surface. The computational method developed uses this set of prominent points to facilitate fast evaluation of the envelope surface. Roughness values obtained by two, two-and-a-half, and three-dimensional evaluation of typical surfaces are also given. This procedure of waviness filtering gives a strong base for an integrated approach for surface and form measurements.     

An exploration of an abrasive water jet cutting front profile

Abrasive water jet (AWJ) now is used as a precision cutting tool. With this tool, dimension tolerance less than 0.1 mm is expected in the cutting process. This dimension tolerance is enough for some applications. However, higher precision is necessary in order to use AWJ in some other applications. To get higher precision in an AWJ cutting process, controlling AWJ beam more accurately is needed, and this further leads to understanding AWJ cutting front more accurately. This paper compared the current cutting front profile exploration methods and then provided a new method to collect AWJ cutting front information accurately. With this new method, a better understanding of the cutting front profile is possible, which further leads to higher precision cutting of AWJ. This paper also demonstrated that the AWJ cutting front profile could be fitted by parabolic curves accurately.     

基于FPGA的高速非接触式位移测量系统

根据光学三角测距理论,开发了一种USB接口的高速非接触式位移测量系统。系统将线性阵CCD上目标反射光点的像素信号通过高速ADC采样转化成数据流,然后用FPGA组成电路进行处理,计算出参考点和检测对象之间的相对位移。该系统具有50MHz的采样率和采用USB2.0总线,测量范围为5厘米到20厘米,测量精度10微米。     

Nano- and submicro-sized three-dimensional shape measuring system using a SAW-based capacitance sensor

SAW-based capacitance sensors were developed by measuring the changes in the voltage ratio between an output inter-digital transducer (IDT) and an input IDT, induced by the variation in the capacitance between hemi-spherical conductive tips with diameters on the order of micrometers. We derived the transfer and sensitivity functions, which describes the ratio of the variation in the output voltage to the variation in the input voltage with a 2-port network model of a SAW based on Mason’s equivalent electro-acoustic circuit and analytical model for the apex capacitance. We then conducted an experiment to verify and measure the transfer function and the 3-D shape. The system was found to have an average resolution of approximately 10 nanometers. We also used the constructed system to measure nano- and submicro-sized 3-D shapes, and verified that the measurement results were accurate.