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1

A review of digital filtering in evaluation of surface roughness

He Baofeng, Zheng Haibo, Ding Siyuan, Yang Ruizhao, Shi Zhaoyao

Metrology and Measurement Systems

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2021

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Vol. 28, nr 2

217--253

EN

Surface roughness is an important indicator in the evaluation of machining and product quality, as well as a direct factor affecting the performance of components. A rapidly developing filtering technology has become the main means of extracting surface roughness. The International Organization for Standardization (ISO) is constantly updating and improving the standard system for filtering technology in order to meet the requirements of technological development. Based on the filters already accepted by the international standard ISO 16610, this study briefly introduces the filtering principle of each filter, reviews the development of each filter in the application of surface roughness, and compares the advantages and limitations of their individual performances. The application range of each filter is summarized and, finally, the future direction of the digital filtering used in surface roughness is extrapolated.

2

Separation Of Non-Periodic And Periodic 2D Profile Features Using B-Spline Functions

Janecki D., Cedro L., Zwierzchowski J.

Metrology and Measurement Systems

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2015

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Vol. 22, nr 2

289--302

EN

The form, waviness and roughness components of a measured profile are separated by means of digital filters. The aim of analysis was to develop an algorithm for one-dimensional filtering of profiles using approximation by means of B-splines. The theory of B-spline functions introduced by Schoenberg and extended by Unser et al. was used. Unlike the spline filter proposed by Krystek, which is described in ISO standards, the algorithm does not take into account the bending energy of a filtered profile in the functional whose minimization is the principle of the filter. Appropriate smoothness of a filtered profile is achieved by selecting an appropriate distance between nodes of the spline function. In this paper, we determine the Fourier transforms of the filter impulse response at different impulse positions, with respect to the nodes. We show that the filter cutoff length is equal to half of the node-to-node distance. The inclination of the filter frequency characteristic in the transition band can be adjusted by selecting an appropriate degree of the B-spline function. The paper includes examples of separation of 2D roughness, as well as separation of form and waviness of roundness profiles.

3

Uproszczona metoda filtracji profili walcowości zmierzonych metodą klatki, wykorzystująca funkcje sklejane i wielomiany trygonometryczne

Janecki D.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2009

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Z. 13

157--166

PL

W celu wyodrębnienia składowych kształtu, falistości i chropowatości mierzonego elementu stosuje się filtry cyfrowe. W artykule zaproponowano prostą dwuetapową metodę filtracji profilu zmierzonego za pomocą strategii klatki. W pierwszym etapie dokonuje się filtracji poszczególnych profili okrągłości i prostoliniowości, a następnie wyznacza się wartości średnie promienia w punktach przecięcia się trajektorii skanowania profili. W drugim etapie dokonuje się ponownej filtracji profili okrągłości i prostoliniowości z dołączonymi warunkami równościowymi, zapewniającymi ciągłość profilu walcowości. Zaproponowany filtr jest odporny na działanie tzw. efektu brzegowego.

EN

In order to separate the profile form components from profile waviness and roughness ones the low pass digital filters are applied. In the paper, a new simply method of filtering the cylindricity profiles measured by means of the cave-bird method is developed. The method applies the functional approach proposed by Krystek. The filtration has two steps. In the first step the profiles are being filtered separately in cross and longitudinal sections and average value of intersections of scanning trajectories are being obtained. In the second step the profiles are being filtered again, but the equals equations ware being add. This equations ensure the continuity of filtered profile at the point of intersection. The method enables to eliminate the edge effect.

4

Podstawy teoretyczne oceny profili walcowości obrotowych części maszyn metodą klatki Część II: Metoda filtracji wykorzystująca podejście funkcjonałowe

Janecki D., Zwierzchowski J.

Pomiary Automatyka Kontrola

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2009

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R. 55, nr 12

1017-1022

PL

W celu rozdzielenia składowych kształtu od składowych falistości i chropowatości stosuje się filtry cyfrowe dolnoprzepustowe. W pracy opracowano metodę filtracji profili walcowości zaobserwowanych metodą "klatki". Wykorzystuje ona tzw. podejście funkcjonałowe. Pozwala to na eliminację efektu brzegowego oraz zapewnia, że w punktach przecięcia trajektorii skanowania wartości promienia przefiltrowanych profili okrągłości i prostoliniowości są równe.

EN

It is assumed that roughness, waviness and form constitute the geometrical surface structure. The components of form with the longest wavelengths can now be extracted using digital low-pass filters. In the case of cylindrical surfaces, the assessment of form requires that a profile be filtered with the aim of eliminating the waviness and roughness constituents. The filtration process selected for a profile registered with the bird-cage method should provide filtration both roundness and straightness profiles. Additionally, it is logical requiring the values of the radii of the filtered roundness and straightness profiles be equal at the points of intersection of the scanning trajectories. The profiles under study were filtered using the so called functional approach, which was introduced to surface metrology by Krystek [2, 3] and further developed by other re-searchers [7]. According to the approach, a filtered profile is modeled as a spline, which assumes a required smooth form due to local stresses proportional to the value of a deviation. The major advantage of the functional approach is the elimination of the boundary effect, which occurs during filtration of straightness profiles. Although it is relatively simple to directly generalize the functional approach to the filtration of a cylindricity profile registered with the bird-cage method (26), the problem is very difficult to solve because of its dimension. Therefore, simplified approach has been applied. First, we filtered each profile separately using the pre-determined methods for roundness and straightness profiles. Subsequently, we filtered the profiles by introducing additional equality conditions (33), which assured profile continuity at the points of intersection of the cylinder scanning trajectories. The proposed two-step filtration algorithm can be combined with the procedure of profile matching discussed in Ref. [1].