Geometrical consideration for mechanical contact between rolling circle and surface roughness as an improvement to the surface profile

2021 ◽  
Vol 15 (1) ◽  
pp. 7846-7859
Author(s):  
Tsuyoshi Shimizu ◽  
Yasutake Hramiishi ◽  
Takaaki Ishii ◽  
Yuzairi Abdul Rahim ◽  
Mohd Fadzil Ali Ahmad ◽  
...  
Keyword(s):  
Contact Point ◽  
Surface Profile ◽  
Displacement Sensor ◽  
Nose Radius ◽  
Rolling Circle ◽  
Actual Surface ◽  
Contact Type ◽  
Measurement Surface ◽  
Surface Profiles ◽  
Tip Radius

This paper describes measurement methods of surface profiles that improve contact-type displacement sensor outputs by focusing on the contact point between the sphere tip of the sensor and the rough surface. We examined the geometry of a surface profile model and compared measurements using various methods with the measurement using a roughness meter. The spherical tip of the contact type displacement sensor touches the measurement surface and detects the displacement. The sphere tip radius of a typical contact-type displacement sensor ranges from 1–3 mm, causing the roughness curve to be “filtered” by the radius of the sphere.  Three methods for estimating the valley portion of the surface profile are evaluated in this study: a) linear approximation of the concave portion of the surface profile, b) function approximation of the concave portion, and c) using the known nose radius of the machining tool. The following sphere tip radii were used to measure actual surface profiles: 0.25 mm, 0.5 mm, 1.0 mm and 1.5 mm. Given the conditions of the experimental model, we found that surface profiles with a roughness that approximates a predictable curve can be measured with a high degree of accuracy.

scholarly journals An Investigation of the High-Frequency Ultrasonic Vibration-Assisted Cutting of Steel Optical Moulds

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 460
Author(s):  
Canbin Zhang ◽  
Chifai Cheung ◽  
Benjamin Bulla ◽  
Chenyang Zhao
Keyword(s):  
Surface Roughness ◽  
Ultrasonic Vibration ◽  
High Frequency ◽  
Optical Glass ◽  
Contact Point ◽  
Cutting Speed ◽  
Optical Quality ◽  
Machining Parameters ◽  
Nose Radius ◽  
Cutting Geometry

Ultrasonic vibration-assisted cutting (UVAC) has been regarded as a promising technology to machine difficult-to-machine materials such as tungsten carbide, optical glass, and hardened steel in order to achieve superfinished surfaces. To increase vibration stability to achieve optical surface quality of a workpiece, a high-frequency ultrasonic vibration-assisted cutting system with a vibration frequency of about 104 kHz is used to machine spherical optical steel moulds. A series of experiments are conducted to investigate the effect of machining parameters on the surface roughness of the workpiece including nominal cutting speed, feed rate, tool nose radius, vibration amplitude, and cutting geometry. This research takes into account the effects of the constantly changing contact point on the tool edge with the workpiece induced by the cutting geometry when machining a spherical steel mould. The surface morphology and surface roughness at different regions on the machined mould, with slope degrees (SDs) of 0°, 5°, 10°, and 15°, were measured and analysed. The experimental results show that the arithmetic roughness Sa of the workpiece increases gradually with increasing slope degree. By using optimised cutting parameters, a constant surface roughness Sa of 3 nm to 4 nm at different slope degrees was achieved by the applied high-frequency UVAC technique. This study provides guidance for ultra-precision machining of steel moulds with great variation in slope degree in the pursuit of optical quality on the whole surface.

scholarly journals A Simple Model to Predict Machined Depth and Surface Profile for Picosecond Laser Surface Texturing

2018 ◽  
Vol 8 (11) ◽  
pp. 2111 ◽  
Author(s):  
Jieyu Xian ◽  
Xingsheng Wang ◽  
Xiuqing Fu ◽  
Zhengwei Zhang ◽  
Lu Liu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Surface Texturing ◽  
Surface Profile ◽  
Picosecond Laser ◽  
Scanning Speed ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Micro Channels ◽  
Surface Profiles ◽  
Simulation Parameters

A simple mathematical model was developed to predict the machined depth and surface profile in laser surface texturing of micro-channels using a picosecond laser. Fabrication of micro-craters with pulse trains of different numbers was initially performed. Two baseline values from the created micro-craters were used to calculate the estimated simulation parameters. Thereafter, the depths and profiles with various scanning speeds or adjacent intervals were simulated using the developed model and calculated parameters. Corresponding experiments were conducted to validate the developed mathematical model. An excellent agreement was obtained for the predicted and experimental depths and surface profiles. The machined depth decreased with the increase of scanning speed or adjacent interval.

scholarly journals How surface stress transforms surface profiles and adhesion of rough elastic bodies

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200477
Author(s):  
Chung-Yuen Hui ◽  
Zezhou Liu ◽  
Nicolas Bain ◽  
Anand Jagota ◽  
Eric R. Dufresne ◽  
...  
Keyword(s):  
Surface Stress ◽  
Periodic Structures ◽  
Surface Profile ◽  
Initial Surface ◽  
One Dimensional ◽  
Patterned Substrate ◽  
Soft Solids ◽  
Elastic Bodies ◽  
Surface Profiles ◽  
Qualitative Changes

The surface of soft solids carries a surface stress that tends to flatten surface profiles. For example, surface features on a soft solid, fabricated by moulding against a stiff-patterned substrate, tend to flatten upon removal from the mould. In this work, we derive a transfer function in an explicit form that, given any initial surface profile, shows how to compute the shape of the corresponding flattened profile. We provide analytical results for several applications including flattening of one-dimensional and two-dimensional periodic structures, qualitative changes to the surface roughness spectrum, and how that strongly influences adhesion.

Experimental and Theoretical Studies of the Fractal Scaling Parameter and the Lateral Scale Dependence of the Asperity Interference

2007 ◽  
Author(s):  
Shao Wang ◽  
Yi Hui Leong
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Numerical Scheme ◽  
Surface Profile ◽  
Density Data ◽  
Fractal Scaling ◽  
Scaling Parameter ◽  
Power Spectral ◽  
Surface Profiles ◽  
The Difference

The fractal scaling parameter was released in a recent study from its artificially assigned constant value to become a measurable parameter for simulated surface profiles. In the present study, this concept was extended to develop schemes for determining the fractal scaling parameter from experimental power spectral density data. The difference in the trends of peaks has been observed between experimental power spectral density data and those of the Weierstrass-Mandelbrot function. A modified W-M function was proposed based on a peak splitting behavior of the power spectrum. To verify a relationship between the interference and lateral length scale for asperities, which is commonly assumed in fractal modeling, a numerical scheme was developed to truncate measured surface profiles for finding asperity interferences for microcontacts of various sizes. This relationship was confirmed by the favorable results from a comparison of the power values obtained from truncation of a surface profile to those obtained by using the fast Fourier transform. A numerical scheme was developed to generate random power spectral density curves and fractal surface profiles for given values of the fractal scaling parameter.

Wheel-Rail Contact Point Calculation of Flexible Wheelset Base on Wheel-Rail Contact Line Method

2011 ◽  
Vol 105-107 ◽  
pp. 1284-1288
Author(s):  
Hao Gao ◽  
Huan Yun Dai
Keyword(s):  
Contact Line ◽  
Contact Point ◽  
Rolling Circle ◽  
Line Method ◽  
Flexible Wheelset ◽  
Point Calculation ◽  
Coupling Dynamic ◽  
Normal Vectors ◽  
Contact Position ◽  
The Impact

Elastic deformation of wheelset should be considered for wheelset dynamic research. In this article, a new wheel-rail contact point searching algorithm that can be used for flexible wheelset simulation was developed based on wheel-rail contact line method. For given position and deformation of wheelset, normal vectors of a point on each rolling circle and its project on rail were calculated to find out possible contact point, which formed wheel-rail contact line. The final contact point was determined by minimum vertical distance of contact line and rail section profile. Rigid-flexible coupling dynamic equations of single wheelset were established and dynamic simulation was executed. The impact of wheelset deformation on wheel-rail contact position and creepage were discussed. Comparison of rigid and flexible wheelset results show that the new method gets more accurate contact point position.

Analysis of Handling Stresses in Thin Solar Silicon Wafers Generated by a Rigid Vacuum Gripper

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Hao Wu ◽  
Shreyes N. Melkote
Keyword(s):  
Stress Distribution ◽  
Dominant Role ◽  
High Stress ◽  
Surface Profile ◽  
Silicon Wafers ◽  
Wafer Surface ◽  
Initial Surface ◽  
Fe Modeling ◽  
Solar Silicon ◽  
Surface Profiles

Breakage of thin solar silicon wafers during handling and transport depends on the stresses imposed on the wafer by the handling/transport device. In this paper, the stresses generated in solar silicon wafers by a rigid vacuum gripper are analyzed via a combination of experiments and numerical modeling. Specifically, stresses produced in monocrystalline (Cz) and multicrystalline (Cast) silicon wafers of different thicknesses when handled by a vacuum gripper are analyzed using the finite element (FE) method. With the measured surface profiles of the wafer and the gripper as input, the handling process is simulated using FE modeling and the stress distribution obtained. The FE modeling results are validated by experimental data of wafer surface profile during handling. The results show that while the vacuum level does not have significant impact on the stress distribution, the initial surface profiles of the thin wafer and gripper play a dominant role in producing regions of high stress in the wafer.

Surface Profile Analysis in Milling with Structured Tool

2019 ◽  
Vol 13 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Fumihiro Uchiyama ◽  
Akihiko Tsuboi ◽  
Takashi Matsumura ◽  
◽  
◽  
...  
Keyword(s):  
Profile Analysis ◽  
Surface Profile ◽  
Polycrystalline Diamond ◽  
Cutting Parameters ◽  
Processing Parameters ◽  
Micro Scale ◽  
Surface Finishes ◽  
Optimum Cutting ◽  
End Mills ◽  
Surface Profiles

Novel end mills with micro-scale structures have recently been developed to promote cutting performances with cutting forces, chip controls, and tool wears. However, the surface profiles are formed corresponding to the structures on the tool edges. The surface finishes, therefore, are worse than those of cuttings with straight edges of the end mills. This paper discusses surface profiles in milling with the structured tool and the cutter axis inclination. An analytical model is presented to simulate the surface profiles for the tool edge shape, the cutting parameters and the cutter axis inclination. Because the surface profiles are controlled in the simulation, the optimum cutting parameters are determined to reduce the surface roughness. Micro-scale nicks were fabricated on polycrystalline diamond edges with a laser machine tool. The sizes and pitches of the nicks were controlled by the laser processing parameters. The cutting tests were conducted to measure the surface profiles. The presented surface profile model was validated by comparing the simulated and the measured surface roughnesses. The surface finish can be improved in milling with the cutter axis inclination in the optimum cutting parameters.

Fabrication and Characterization of 3D Aspheric Microlenses with Arbitrary Surface Profiles Based on a Novel Excimer Laser Contour Scanning Method

2006 ◽  
Vol 505-507 ◽  
pp. 67-72
Author(s):  
Yung Chun Lee ◽  
Chun Ying Wu
Keyword(s):  
Excimer Laser ◽  
Surface Profile ◽  
Aspheric Surfaces ◽  
Scanning Method ◽  
System A ◽  
Continuous Surface ◽  
Surface Profiles ◽  
Profile Accuracy ◽  
Method Show

This paper presents a new method for fabricating 3D microstructures with an excimer laser micromachining system. A novel mask contour scanning method is developed for obtaining precise 3D microstructures with pre-described continuous surface profile. Two different microlenses with spherical and aspheric surfaces profiles with dimension less than 200 μm are fabricated on polycarbonate (PC) samples. The surface profiles are measured and compared with their theoretical counterparts. Excellent agreements both in profile shapes and dimensions are achieved. The surface roughness (Ra) of the machined surfaces is also measured and is less than 10 nm. The machining profile accuracy and surface smoothness of this proposed micromachining method show great potentials in fabricating micro-optic components such as aspheric microlenses or microlens arrays.

Sign in / Sign up

Export Citation Format

Share Document