一种新型滚动轴承表面形貌测量仪

介绍了一种新型的滚动轴承表面形貌测量仪,它采用一种全新的能越过陡峭表面的二维位移传感器和垂直扫描三维工作台组成一个闭环控制系统,将传统的触针移动扫描方式改变为工作台移动扫描方式。在测量工件时,二维位移传感器的测量杠杆总是不断地回到平衡位置,因此即使增大量程,由杠杆转动所引起的测量非线性误差也非常小。该仪器不仅可进行二维轮廓测量,还可进行三维形貌测量,具有大量程、高精度、小测量力和更多测量参数等特点。     

3-Dimensional profile distortion measured by stylus type surface profilometer

In this paper, the distortion effect in measured profiles caused by stylus tip radius size of stylus-typed surface profilometer was analyzed in terms of 2D and 3D. On the basis of our analysis results, we propose selection criteria for the stylus tip radius to improve the reliability of measurement results. For this purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3-dimensional surface texture used in simulation was obtained using an Atomic Force Microscope (AFM) on an actual machined surface to improve the reliability of simulation results. The simulation results are compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study is confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency components field using a stylus type profilometer is clarified, and the selection criteria of the stylus tip radius for measurement is proposed considering the surface texture characteristics of the specimen. The purpose of this paper is to provide a basis of a simple and effective method which could be an alternative of some engineering standard that specifies selection of stylus tip radius for the measurement using only nominal Rq for machined surface.     

影响待测物面测量误差的因素及补偿

分析被测物面对激光三角法测量技术的影响,从原理、位移传感器的非线性补偿、被测表面倾角、被测表面特征(颜色、粗糙度、光泽)几方面分析误差产生的原因。探讨各因素的误差补偿方法,对传感器进行非线性误差标定,测量出其非线性误差曲线图;使用标注件标定激光头本身倾角误差,对绘制倾角误差测量结果做曲线拟合;对被测件表面的颜色处理;在非特定条件下,可以忽略表面光泽度和粗糙度;最后综合上述过程,得出测量结果。该方法提高了测量精度。对于小型机电,电子产品外形反求测量,提高其生产过程中的测量精度,具有一定指导作用。     

压电微音叉扫描探针显微镜测头研究

压电微音叉具有良好的谐振特性，并易于实现其振动的检测。利用这些特性，与钨探针结合，构成了一种新型的表面轮廓扫描测头。该新型测头与X-Y压电工作台结合，采用与TM-AFM相同的工作原理，构成了扫描探针显微镜。介绍了压电微音叉扫描测头的构成、工作原理及主要特性，给出了所构成的扫描探针显微镜测量系统。通过实验及其结果，证明了新型测头具有高垂直分辨率、低破坏力等优点。除此之外，由于采用了有效长度大的钨探针，使大台阶微观表面的测量成为可能。     

The influence of stylus flight on change of surface topography parameters

Theoretical and experimental work on stylus flight is described. The paper describes the development of a simulation model for assessing the magnitude of surface topography distortion by stylus flight. Experiments on the surfaces support the theoretical model, which predicts stylus flight. The measurements of different surface topographies (including surfaces after grinding, turning, honing, milling) were done using Talyscan 150 measuring instrument with four traversing speeds (0.5, 1, 2 and 3 mm/s). The results of theoretical considerations and experiments were compared. The effect of stylus flight on surface topography parameters of measured surfaces basing on experimental investigation was assessed. The tendency was found that slope decreased, decrease of amplitude parameters and increase of horizontal parameters took place, but these effects were different for various surface types. The simulation procedure assured good accuracy of surface topography parameters changes.Based on theoretical investigation, the effect of stylus flight and stylus tip radius on parameters of computer-generated profiles was predicted. The choice of traversing speed to different types of surfaces was done. The parameters of biggest changes caused by error in measurement due to stylus kinematics were selected.     

Ball tip–stylus tilt correction for a stylus profilometer

Ball tip and stylus tilt are two error sources found in coordinate measurement machines (CMMs). The magnitude of these errors is dependent on the ball tip radius and the degree of misalignment between the stylus motion axis and lateral referencing plane determined by the x and y axes of the CMM used. It is shown that these two errors are actually coupled and that their correction can be accomplished in one process. The overall benefit and versatility of this correction routine on a more general basis are given.     

On-machine profile measurement of a micro cutting edge by using a contact-type compact probe unit

A new contact-type on-machine measurement system is designed and developed for the evaluation of a micro cutting edge profile. The measurement system is composed of a compact probe unit having a sharp stylus mounted on a flexible beam, an inner displacement sensor for the detection of the stylus displacement, and a two-axis precision positioning system. For the evaluation of tool faces having a steep slope, a new probing procedure with the enhancement of the inner displacement sensor integrated into the probe unit is newly proposed. After the design and development of the probe unit, the feasibilities of the developed measurement system and the proposed probing procedure are demonstrated through some basic experiments. Regarding the out-of-straightness and angular error motion of the two-axis positioning system employed in the developed measurement system, a pair of length gauges is newly employed to reduce the influences of error motions of the stage system. The topographic profile of the micro cutting edge obtained by the measurement system with the modified probe unit is then compared with those obtained by a commercial stylus profiler and a laser confocal microscope. The feasibility and effectiveness of the developed on-machine tool edge profile measurement system are also demonstrated through uncertainty analysis based on the GUM with the Monte-Carlo method.     

Effect of a skid on the accuracy of measuring surface roughness

The vertical movement of the skid caused by surface irregularities introduces some error into the measured value of surface roughness parameters. A theoretical and experimental investigation into the negative effect of the skid on measuring accuracy is reported.The effect of the skid for unidirectional surface roughness is greater than that for non-directional surface roughness. The effect increases with increase in the tip radius of the skid. The influence of the distance between the skid and the stylus on the effect of the skid is small and an electrical high pass filter reduces the effect.     

双盘式渐开线测量仪测点位置调整方式

分析了双盘式渐开线测量仪中测点位置偏差对渐开线齿形测量的影响,探讨了高精度调整测点位置的两种方法:试验调整法与误差补偿调整法。试验调整法是根据测点偏离导轨平面测量渐开线齿形时,测量结果中齿形角小于实际值的原理,调整测头处于不同位置并测量渐开线齿形,齿形角最大的测量曲线对应的测点位置即为最佳位置。误差补偿调整法是在测点处于高于导轨平面的两个位置时,分别测量同一渐开线齿形,通过对测点偏移量逐次试值,补偿两次测量结果,使得测量结果中齿形偏差相同,获得测头偏移量。分析得出,上述两种方法调整测头位置的极限偏差分别为±0.010 mm和±0.015 mm,均可满足1级(GB/T10 095.1-2 001)渐开线齿形的测量要求。     

Error in measurement due to stylus kinematics

A study of the error in measurement due to the kinematics of the stylus of the measuring instrument is presented. A method of determining the point of separation of the stylus from the measured surface and the path of the stylus after separation is established. Stylus spring stiffness to prevent separation of the stylus and to attain a minimum measuring force is also established.     

Dynamic modelling of the fidelity of random surface measurement by the stylus method

A numerical simulation has been used to systematically investigate the characteristics of a stylus surface profiling instrument. The model bridges together previously used concepts to incorporate both tip size and tip dynamics. The dynamics incorporate a tip flight phenomenon, inferring detachment from zero value of the reaction force and the trajectory from a free vibration solution to a second order system. Tip shape is handled by a rigid kinematic model. Following brief discussions of the modelling and the process for generating test profiles with defined correlation lengths, the influences of the inherent parameters of the stylus instrument and the testing method on the measurement fidelity are examined. The tip shape effect of the stylus instrument is also considered in the dynamic measurement. It is noted that the finite tip size can increase the critical scanning speed to avoid tip flight, but decreases the signal fidelity of the measurement due to the bridging effect.     

Developing a novel tri-switch tactile probing structure and its measurement characteristics on micro-CMM

This paper describes a novel tri-switch tactile structure assembling process and its measurement characteristics on micro-CMM. After assembling micro-ruby ball-ended stylus tips on micro-EDM, the spherical stylus was glued onto the CMM’s probing head manually. A novel tri-switch contacting structure was proposed to trigger the electro signal while the stylus tip makes contact with a micro-object. The experimental results show that the uncertainty could be as small as 0.08 μm at same the point detected repeatedly in the vertical direction. The depth of micro-hole and the profile of spherical lens are also selectable by use of this tri-switch tactile structure. This novel low-cost tri-switch triggering system may have promising future use on micro-CMM probing heads to measure micro-products’ geometric profiles.     

The effect of tip size on the measured Ra of surface roughness specimens with rectangular profiles

When measuring rectangular and trapezoidal profile roughness specimens, the stylus tip increases the measured profile peak width and decreases the measured valley width. This can cause either an increase or a decrease in the apparent roughness average Ra, depending on the tip size and the ratio of peak width to valley width. Sometimes the change is larger than the combined measurement uncertainty from other sources. This raises the question as to whether measured surface parameters should be corrected for the effect of tip size.     

Spectral analysis for the effect of stylus tip curvature on measuring rough profiles

Spectral analysis and computer simulation are adopted to investigate the tracing of a random profile with a mechanical profiler with a spherical tipped stylus. It is shown that the measuring error strongly depends on the ratio of the radius of stylus tip r to the rms roughness σ and the ratio of the 1/e correlation distance b to the rms roughness σ. By using the concept of critical wave number, spectral density of measured profile can be estimated. Also, formulas are developed to estimate the rms error and the critical sampling interval.     

激光跟踪仪测角误差的现场评价

激光跟踪仪是基于角度传感和测长技术相结合的球坐标测量系统,其长度测量采用激光干涉测长方法,可直接溯源至激光波长,因此,激光跟踪仪的长度测量精度远高于角度测量精度,相对而言,测角误差就成为评价跟踪仪测量精度的重要指标。为了对现场测量激光跟踪仪的测角误差进行快速有效地评价,采用跟踪仪多站位对空间中测量区域内若干个被测点进行测量,与传统基于角度交汇原理的多站位冗余测量不同,利用各站位所观测的高精度测长值建立误差方程,并通过测长方向的矢量位移对跟踪仪测长误差进行约束,获得被测点三维坐标在跟踪仪水平角和垂直角方向上的改正值,以此来评价激光跟踪仪的测角误差。通过Leica激光跟踪仪AT901-LR进行了多站位测角误差评价实验,在现场测量条件下,跟踪仪水平和垂直方向测角误差约为0.003 mm/m(1σ),符合跟踪仪的测量误差特性。     

A computer system for the measurement of cell and nuclear sizes

A semi-automated system has been developed for the measurement of cell (perikaryal), nuclear and nucleolar areas. The system consists essentially of a Graf/Pen data tablet (with its associated acoustical stylus and tablet electronics), an optical input system such as a camera lucida, and a small digital computer. The perikaryal, nuclear and nucleolar outlines are traced in sequence with the stylus which, on contacting the tablet surface, emits a high frequency acoustic wave that is sensed by X and Y strip microphones along the left and upper edges of the tablet. The acoustic signal is converted by a simple program into a series of X and Y coordinates which are sampled at several points around the perimeter of the profile. When the stylus tip re-enters a 1 mm stationary window set up around the starting point, the measurement is automatically terminated and the data for this profile is printed out and stored in memory for subsequent statistical analysis. The system has an overall accuracy of about 1% and in practice it has been possible to measure objects at least ten times more rapidly than by any of the other currently available methods. The hardware and software features of the system are detailed and a number of additional uses for the system are described.     

Measurement of form error of a probe tip ball for coordinate measuring machine (CMM) using a rotating reference sphere

This study presents a method of measurement of the form error of the tip ball in the tactile probing systems of a coordinate measuring machine (CMM) by using a rotating reference sphere. The measurement of the form error of the CMM probe tip was conducted without the use of additional external measuring instruments or sensors. The form errors of the probe tip ball and the reference sphere were separated from the probing coordinates of CMM by rotation of the reference sphere. The effectiveness of the proposed method was evaluated based on an uncertainty analysis. The uncertainty in measurement of diameter of the probe tip ball was estimated to be less than 0.5 μm.     

A spiral scanning probe system for micro-aspheric surface profile measurement

This paper presents a novel spiral scanning probe measurement system which is developed to achieve precise profile measurements of micro-aspheric surfaces. The system consists of a scanning stage (a spindle and a linear slide) and a contact-type displacement sensor. The contact-type sensor is employed for the scanning of the micro-aspheric surface. The micro-aspheric object is set on the spindle, and the contact-type displacement sensor is set on the linear slide. The motions of the spindle and the linear slide are controlled synchronously so that the micro-aspheric object is scanned spirally for high-speed measurement. The motions of the stage are used as the scanning datum for the profile measurement. Because the error motions of the stage are estimated to be on the order of tens of nanometer, these errors are measured and compensated to achieve precise measurements. The alignment error between the spindle rotation axis and the probe tip of the contact-type displacement sensor, which is called the centering error, is confirmed to cause considerable measurement error of the micro-aspheric surface profile. Methods are proposed to make the alignment accurately. Experiments of surface profile measurement of a micro-aspheric lens are also carried out in the measurement system.     

Haptic-STM: a human-in-the-loop interface to a scanning tunneling microscope

The operation of a haptic device interfaced with a scanning tunneling microscope (STM) is presented here. The user moves the STM tip in three dimensions by means of a stylus attached to the haptic instrument. The tunneling current measured by the STM is converted to a vertical force, applied to the stylus and felt by the user, with the user being incorporated into the feedback loop that controls the tip-surface distance. A haptic-STM interface of this nature allows the user to feel atomic features on the surface and facilitates the tactile manipulation of the adsorbate/substrate system. The operation of this device is demonstrated via the room temperature STM imaging of C(60) molecules adsorbed on an Au(111) surface in ultra-high vacuum.     

Measurement of multi-degree-of-freedom error motions of a precision linear air-bearing stage

This paper describes the measurement of straightness error motions (vertical straightness and horizontal straightness) and rotational error motions (pitch, yaw and roll) of a commercial precision linear air-bearing stage actuated by a linear motor. Each of the error motions was measured by two different methods for assurance of reliability. The stage was placed in the XY-plane and moved along the X-direction. The pitch error and yaw error, which were measured by an autocollimator and the angle measurement kit of a laser interferometer, were about 8.7 and 1.6 arc-s, respectively, over a travel of 150 mm with a moving speed of 10 mm/s. The roll error was measured by the autocollimator through scanning a flat mirror along the X-direction. The second method for roll error measurement was to scan two capacitance-type displacement probes along the flat surface placed in the XZ-plane. The two probes with their sensing axes in the Y-direction were aligned with a certain spacing along the Z-axis. The roll error can be obtained by dividing the difference of the outputs of the two probes by the spacing between the two probes. The roll error was measured to be approximately 11.8 arc-s over the 150 mm travel. The horizontal straightness error and the vertical straightness error (Y- and Z-straightness errors) were measured by using the straightness measurement kit of the laser interferometer. The second method for straightness measurement was to scan the flat surface with a capacitance-type displacement probe. The horizontal and vertical straightness errors of the stage over the 150 mm travel were measured to be approximately 207 and 660 nm, respectively.