• Title/Summary/Keyword: Surface flatness

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A Rational Quantity of Measurement for Finding Flatness of a Surface Table (정반 평면도 평가를 위한 측정점의 합리적인 개수의 결정)

  • Hyun, Chang-Hun;Shin, Sang-Cheol;Park, Hung-Sik
    • Journal of Industrial Technology
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    • v.18
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    • pp.181-186
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    • 1998
  • The flatness is the most important nature for the surface table. For finding such a flatness, the surface is surveyed along a number of straight lines parallel to the edges of table, which form a grid. Next, the variations in height of the grid points are measured relative to a datum point. If the number of such points is increased. It is not necessarily to use many grid points for finding the original flatness of a measured surface table. So, it is necessary to find the rational quantity of such grid points. It is found that about 220 points per $1m^2$ of surface table for measurement is the rational quantity with less than about 15% error of the original flatness.

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Relation between Flatness of Surface Plates adn Numbers of Measurement-Point (정반 평면도와 측정점 개수와의 수학적 관계)

  • 현창헌
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.4
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    • pp.99-105
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    • 1999
  • The flatness is the most important nature for the surface plates. For finding such a flatnes a surface plate is surveyed along a number of straight lines parallel to the edges of plate which form a grid pattern. Next the variations in height of the grid points are measured relative to a datum point. the relation between the number of such grid points and the flatuness of a measured surface plate is formulated in this study. In addtion it is found that the grid-point-numbers suggested by KS B 5254 and JIS B 7513 have very poor reliability for estimation of flatness incase of the surface plates with poor original flatness.

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Surface Flatness Test using 2-Bucket Algorithm Phase-shifting Interferometry (2-Bucket 알고리즘 위성 전이 간섭계를 이용한 평면 편평도 측정)

  • 정근욱;김동욱;길상근;박한규
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.29A no.11
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    • pp.62-69
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    • 1992
  • In this paper, a measurement system of surface flatness test using 2-Bucket algorithm phase-shifting interferometry is designed and constructed. In the conventional surface flatness test system using phase shifting interferometry, it is needed more than 3 fringe datas but we propose 2-Bucket algorithm phase-shifting interferometry which only uses two fringe datas. 2-Bucket algorithm uses the relative phase differences of the neighbour pixels. If we watch the result of phase-shift error test simulation, 2-Bucket algorithm has the same calculating values that 3-Bucket, 4-Bucket and 5-Bucket algorithm have them. Experiments have been carried out on the silicon wafer. The measurement of silicon wafer's surface flatness shows that the flatness topography using 2-Bucket algorithm is similar to that of other algorithms.

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Surface flatness and distortion inspection of precast concrete elements using laser scanning technology

  • Wang, Qian;Kim, Min-Koo;Sohn, Hoon;Cheng, Jack C.P.
    • Smart Structures and Systems
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    • v.18 no.3
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    • pp.601-623
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    • 2016
  • Precast concrete elements are widely used in the construction of buildings and civil infrastructures as they provide higher construction quality and requires less construction time. However, any abnormalities in precast concrete surfaces such as non-flatness or distortion, can influence the erection of the elements as well as the functional performance of the connections between elements. Thus, it is important to undertake surface flatness and distortion inspection (SFDI) on precast concrete elements before their delivery to the construction sites. The traditional methods of SFDI which are conducted manually or by contact-type devices are, however, time-consuming, labor-intensive and error-prone. To tackle these problems, this study proposes techniques for SFDI of precast concrete elements using laser scanning technology. The proposed techniques estimate the $F_F$ number to evaluate the surface flatness, and estimate three different measurements, warping, bowing, and differential elevation between adjacent elements, to evaluate the surface distortion. The proposed techniques were validated by experiments on four small scale test specimens manufactured by a 3D printer. The measured surface flatness and distortion from the laser scanned data were compared to the actual ones, which were obtained from the designed surface geometries of the specimens. The validation experiments show that the proposed techniques can evaluate the surface flatness and distortion effectively and accurately. Furthermore, scanning experiments on two actual precast concrete bridge deck panels were conducted and the proposed techniques were successfully applied to the scanned data of the panels.

Development of On-machine Flatness Measurement Method (평면도 기상 측정 방법 개발)

  • 장문주;홍성욱
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.3
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    • pp.187-193
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    • 2003
  • This paper presents an on-machine measurement method of flatness error fur surface machining processes. There are two kinds of on-machine measurement methods available to measure flatness errors in workpieces: i.e., surface scanning method and sensor scanning method. However, motion errors are often engaged in both methods. This paper proposes an idea to realize a measurement system of flatness errors and its rigorous application for estimation of motion errors of the positioning system. The measurement system is made by modifying the straightness measurement system, which consists of a laser, a CCD camera and processing system, a sensor head, and some optical units. The sensor head is composed of a retroreflector, a ball and ball socket, a linear motion guide unit and adjustable arms. The experimental .results show that the proposed method is useful to identify flatness errors of machined workpieces as well as motion errors of positioning systems.

New Glass Ceramics for Hard Disk Substrates with Improved Surface Flatness

  • Utsuno, Futoshi;Yamada, Yusuke;Takeya, Huminori;Yasui, Itaru
    • The Korean Journal of Ceramics
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    • v.5 no.4
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    • pp.363-367
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    • 1999
  • New glass ceramics were investigated for the application as substrates to be used in hard disk devices. The glass system to precipitate lithium di-silicate was studied so as to optimize the composition to realize very high surface flatness. The addition of small amount of several metal oxides with high valences had very drastic effects on the microstructure, because they played a role of crystallization agents, and consequently it determined surface flatness even after the polishing process. The possible mechanism changes of crystal growth due to the addition of metal oxides were discussed in relation to the final micro-texture development. The glass ceramics with very high surface flatness(Ra=7.1 $\AA$) was obtained by the addition of the mixture of $P-2O_5 \;and \;MoO_3$ as crystallization agents.

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Effects of the Tool Path on the Geometric Characteristics of Milled Surface (가공경로가 밀링가공면의 기하학적 특성에 미치는 영향)

  • Park, Moon-Jin;Kim, Kang
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.6
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    • pp.58-63
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    • 1998
  • There are lots of factors that are related to the geometric characteristics of machined surface. Among them, the tool path and milling mode (up cut milling or down cut milling) are the easiest controllable machining conditions. Thus, the first objective of this research is to study the effects of them on the milled surface that is generated by an end milling tool. To get precision parts, not only the machining process but also the measurement of geometric tolerance is important. But, this measurement requires a lot of time, because the infinite surface points must be measured in the ideal case. So, the second objective is to propose a simple flatness measurement method that can be available instead of the 3-D geometric tolerance measurement method, using a scale factor and characterized points. Finally, it is also shown that the possibility of flatness improvement by shifting the consecutive fine cutting tool path as compared with the last rough cutting tool path.

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A Study on the Cross Rolling for Improvement of Flatness of Plate (판재의 편평도 향상을 위한 교차압연에 관한 연구)

  • Nam K. O.;Seo K. S.;Rho B. R.;Hong S. I.
    • Transactions of Materials Processing
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    • v.14 no.1 s.73
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    • pp.43-48
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    • 2005
  • The production of metal strip with uniform thickness and flatness are two important problems associated thin strip rolling. The thickness and flatness of strip are affected by the flattening of contact surface between strip and roll, the elastic recovery and the bending of roll. Especially, the flatness of the strip is greatly affected by bending deflection of roll. The roll must be designed considered the elastic deformation of roll. This study describes the measurement of thickness and flatness of strip and shows the crown roll for producing flat strip. But it is difficult to produce the crown roller. The cross rolling that is a simple method which can produce the flat strip is introduced and it is found the optimal cross angle for improvement of flatness of plate. These problems are solved by the MARC code on the basis of elastic-plastic material and the updated Lagrangian formulation.

A Study on the utilization of electronic micrometer for flatness measurement of precision surface plate (전기마이크로미터를 이용한 정밀측정용 정반의 평면도 측정에 관한 연구)

  • Kim, Gu-Yeong;Woo, In-Hun;Im, Jae-Seon;Jeong, Myeong-Se;Kim, Jong-Eok
    • Journal of the Korean Society for Precision Engineering
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    • v.4 no.3
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    • pp.52-59
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    • 1987
  • The flatness of a precision surface plate is generally measured by using precision angular measuring instruments such as laser interferometers, autocollimators and electronic levels. Since these instruments are expensive and measurement procedures are complex, such methods are not widely used in industries. In this study, an electronic micrometer that is easy to use and inexpensive to produce was developed in order to solve this problem. The flatness of a black granite surface plate, measured using this device was compared with the values obtained by using the conventional three methods. The results were consistent within ${\pm}1{\mu}m$. It proves that the flatness measuring method using electronic micrometers can be utilized for quantitative measurement. An accessory device that can improve the precision of measurement by attaching to the electronic micrometer was also designed and fabricated.

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The uniform polycrystalline 3C-SiC thin film growth by the gas flow control (가스흐름 제어에 의한 균일한 다결정 3C-SiC 박막 성장)

  • Yoon, Kyu-Hyung;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.92-92
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    • 2008
  • The surface flatness of heteroepitaxially grown 3C-SiC thin films is a key factor affecting electronic and mechanical device applications. This paper describes the surface flatness of polycrystalline 3C-SiC thin films by the gas flow control according to the location change of geometric structure. The polycrystalline 3C-SiC thin film was deposited by APCVD(Atmospheric pressure chemical vapor deposition) at $1200^{\circ}C$ using HMDS(Hexamethyildisilane : $Si_2(CH_3)_6)$ as single precursor, and 5 slm Ar as the main flow gas. According to the location of geometric structure, surface fringes and flatness changed. It shows the distribution of thickness is formed uniformly in the specific location of the geometric structure.

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