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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Využití hodnocení textury povrchu při výrobě revolveru / Utilization of surface texture evaluation in revolver production

Kolena, Robert January 2020 (has links)
This diploma thesis addresses the issue of using the evaluation of surface texture in the manufacture of revolver with aplication to a cock. It deals with the detection of imperfections of production operations, the proposal of corrective measures and its implementation. The use of new grinding wheel was chosen as a corrective measure. The Rzmax parameter was used to specify the surface texture after miling and a combination of the Rzmax and Rpmax parameters was used to specify surface texture after grinding.
12

Využití souřadnicového měřicího stroje pro hodnocení kvality povrchu / Use of a coordiante measuring machine for surface quality evaluation

Vančurová, Martina January 2018 (has links)
This master’s thesis deals with the use of a coordinate measuring machine probe for surface texture evaluation. The thesis’ goals were to describe the Renishaw’s SFP2 probe, to analyze the measurement system of the probe and a common stylus instrument, to carry out a demonstrative measurement, to analyze measurement results and to give practical recommendations. The measurement system analysis of the SFP2 consists in the evaluation of minimal specification limits of selected roughness parameters, for which gauge capability can be proven. The analysis results are compared with the results of the measurement system analysis of the Surtronic 25 profilometer. The differences in the measuring processes of mentioned devices are demonstrated by surface texture inspection of torque converter body. For the measurement result analysis, uncertainties in the selected surface texture parameters are calculated in two ways. Finally, recommendations for the producer of the probe and for its users are worked out. The results of this thesis may contribute to a wider use of a coordinate measuring machines for surface quality evaluation.
13

Einfluss von verschiedenen Erodierstrukturen auf den Reibwert von Kunststoff-Kunststoff Paarungen

Bergmann, André 21 December 2016 (has links) (PDF)
Im Beitrag werden bei verschiedenen Lastkollektiven und zwei Reibgeschwindigkeiten die Erodierstrukturen K27, K36, K42 und die Ätzstruktur K36 mit glatten Probekörpern hinsichtlich des Reibwertes und des Verschleißverhaltens untersucht. Als strukturierte Probekörper kommen die Kunststoffe POM und PA und als Gegenkörper zwei verschiedene PE-UHMW´s zum Einsatz. Die Ergebnisse zeigen eine deutliche Abhängigkeit des Reibwertes von der Oberflächenstruktur der Probekörper, jedoch ist die Senkung des Reibwertes stark von den Belastungsparametern Normalkraft und Reibgeschwindigkeit abhängig.
14

A study of the surface finish produced by grinding

Jones, G. J. January 1985 (has links)
A survey of the literature of grinding and surface texture shows the influence of dressing and wear on surfaces involved in the process and the advantages of stylus profilometry for data collection from both grinding wheels and ground surfaces. Statistical analysis is favoured for surface profile characterization and, of the various parameters used, power spectral density alone offers some prospect of effective comparison between these surfaces. Work on grinding with single crystals of natural corundum was eventually discontinued in favour of experiments with conventional bonded grinding wheels subjected to a dressing operation and some wear in grinding steel surfaces. Statistical parameters representing the surfaces are computed using data obtained from profilograms. Results in terms of power spectral density are presented showing progressive improvement following upon developments in apparatus and methods which facilitated the use of larger surface profile samples. Transfer functions are used to relate power spectra representing corresponding pairs of surfaces. The significance of power spectral density applied to surface profile characterization is discussed and, in this context, it is suggested that these should be described as variance spectra. Attention is drawn to certain disadvantages of variance spectra applied to grinding wheel and ground surface profiles. Methods designed to improve presentation of variance spectra lead to development of a proposed new and more suitable spectrum in which density of standard deviation of surface profile ordinates with respect to frequency is plotted against frequency. Transfer functions calculated from related pairs of these standard deviation spectra show a strong linear correlation with frequency and offer prospects of convenient comparison between the profiles of the various surfaces involved in grinding.
15

Three-dimensional pavement surface texture measurement and statistical analysis

Liu, Qingfan 09 January 2016 (has links)
Pavement texture has been measured predominantly by using two-dimensional (2D) profile methods. The 2D profile based mean profile depth (MPD) is still the well accepted texture index which has been found inadequate to characterize pavement texture especially when tire/pavement friction and noise are involved. There is a lack of standard 3D texture indices which show strong correlation with pavement friction and noise. There is a need to use 3D texture measurement for more comprehensive understanding of texture. The objectives of this thesis are to characterize pavement surfaces using 3D texture parameters based on 3D texture measurement and to explore the relationship between 3D texture parameters, pavement friction, and pavement noise. Field tests are conducted at various pavement sections for the measurements of texture, friction, and noise. The tested pavements include Interstate highway, MnROAD test facilities, airport runway, and municipal streets. The findings and contributions of this thesis are: • The pavement surface texture is measured in a 3D manner by using a line-laser scanner with both horizontal sample interval and vertical accuracy better than 0.05 mm. • A 3D texture analysis procedure with discrete wavelet transform (DWT) is proposed to separate macrotexture from microtexture and to define texture indices independently. • 3D parameters for macrotextures and microtexture are proposed and verified by field tests. • The relationship between 3D and 2D macrotexture indices [i.e. SMTD and MPD; Sq and root mean square roughness (RMSR)] are established, which is useful for the purposes of data comparison between 3D and 2D methods. • The relationship is investigated between 3D macrotexture parameters (SMTD and Sq) and pavement friction and noise. • It is found that texture distribution indices (i.e. Ssk and Sku) are significant contributors to pavement friction and noise. The new 3D texture analysis procedure and texture indices proposed in this thesis can be used to characterize various pavement textures (concrete pavement, asphalt pavement, and pavement contains recycled materials) in 3D manner, to compare 3D with 2D texture measurement/indices for quality control purposes, and to evaluate and predict pavement friction and noise. / February 2016
16

Kalibrace koherenčního rastrovacího interferometru Talysurf CCI / Calibration of Talysurf CCI coherence scanning interferometer

Varava, Anastasia January 2017 (has links)
This master’s thesis deals with calibration of a coherence scanning interferometer Talysurf CCI Lite. Basic terms related to surface texture evaluation were described along with selected profile and areal surface texture parameters. The working principle and design of the calibrated instrument were explained. Manufacturer’s calibration procedure was analyzed in relation to the definition of calibration in the International vocabulary of metrology. Further calibration steps leading to calculation of measurement uncertainty were presented. Last but not least, measurement uncertainties of areal surface texture parameters Sq and Sz were evaluated. The procedures and results described in this thesis may contribute to wider use of non-contact surface texture measuring instruments.
17

Hodnocení kvality ventilu termostatu / Quality assessment of a thermostat valve

Kropáč, Ondřej January 2019 (has links)
The automotive thermostat currently contributes significantly to the potential to reduce the output of the exhaust gases. The heart of the modern thermostat is the ball valve assembly which also deals with this master‘s thesis. First of all the principles of the quality of the automotive thermostat are described with the choice of further deeper examined properties. The manufacturing process of a ball element and PTFE sealing ring is described. Subsequently the problem of increased production of nonconforming products in production is studied focusing on the surface texture of teflon ring and shape analysis of the ball element. Finally a recommendation for practice with regard to the reduction of additional costs associated with poorly manufactured part is created and further action on this issue is recommended.
18

Analýza plastových materiálů vyrobených aditivní technologií 3D tisku / Analysis of Plastic Materials Produced by Additive 3D Printing Technology

Spišák, Lukáš January 2020 (has links)
The diploma thesis deals with the influence of colouring additives and setting of the process parameters of 3D printing on the mechanical and surface properties of samples made of PLA material. The work describes the process of filament production, as well as the printing of normalized samples on a 3D printer using the additive method Fused Deposition Modeling. The impact of 3 types of colouring additives is evaluated on the basis of tensile test, hardness test and surface analysis. The evaluated quantities are primarily tensile strength, hardness, surface texture, roughness and corrugation. The work also evaluates the influence of the percentage of sample filling, the direction of the fibres of the inner filling and the orientation of the samples in the printing chamber of the 3D printer on the mechanical properties. The results are evaluated on the basis of the tensile test and the evaluated quantities are mainly the tensile strength, the ultimate stress and the modulus of elasticity in traction. The work is completed by evaluating the results and overall recommendations for filament manufacturers and users.
19

Hodnocení čelního těsnícího provedení povrchu pomocí charakteristik textury povrchu / Assessment of face seal performance based on surface texture characteristics

Kučera, Pavel January 2008 (has links)
Diploma work dealing with assessments facing the sealing fulfilment surface describes and compares surface topography with the aim of analyzing the most significant characteristic parametrs and factors influencing seal and functional reliability in a decisive way. The most suitable parametrs of sealing which were designated : material ratio Rmr and parametrs Rpk, Rk and Rvk.
20

Souvislost vad řezu s řeznými parametry při řezání abrazivním vodním paprskem / Connection of mistakes cut with cutting characteristics at abrasive water jet cutting

Mareš, Pavel January 2013 (has links)
The aim of this thesis is to determine the area where there is no random step change in cutting edge roughness. This area is established on the basic of samples created by the abrasive water jet cutting method with variation of technologic parameters.

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