Papers by Keyword: Surface Defects

Abstract: The paper sums up the results of a complex analysis, using metallographic, microfractograpic and other methods, with the aim of establishing the cause of fractures appearing in bolts of a terminal board. The analysis has shown unambiguously that the bolt failure was a synergic effect of inadequately performed heat treatment and hydrogenation that occurred in course of surface treatment via pickling and subsequent zinc plating.

Abstract: With the extended applications of hexagonal silicon carbide (h-SiC) in the various fields, particularly in the application of the electronic devices, more and more attentions have been focused on the micro structures as well as their physical properties of h-SiC surface. In this study, we have performed the first principal calculations to compare the formation energies of four typical defects (Vc, Vsi, C_I and Si_I) on the 4H-SiC (0001) surface as well as in the interior layers. Due to the surface reconstruction and the reduced lattice constrain, the optimized structures of the defects on/near the 4H-SiC (0001) surface are quite different from the ones in the deeper layers. The distinguished formation energies as function of chemical potential indicate that we may control the defects concentrations in different layers by tuning the environmental conditions. This theoretical work provides a significant understanding to the formation mechanism of the point defects on the 4H-SiC surface, and paves a way to the modification of the SiC surface via electron irradiation or ion implantation with micro-defects introduced.

Abstract: The quality of product of manufacturing industries depends on dimension accurately and surface roughness quality. There are many types of surface defects and levels of surface roughness quality. Ironing process is one type of metal forming process, which aims to reduce the wall thickness of the cup-shaped or pipes products, thus increasing the height of the wall. Manually surface inspection procedures are very inadequate to ensure the surface in guaranteed quality. To ensure strict requirements of customers, the surface defect inspection based on image processing techniques has been found to be very effective and popular over the last two decades. The paper has been reviewed some papers based on image processing for defect detection. It has been tried to find some alternatives of useful methods for product surface defect detection of ironing process.

Abstract: Used the influence of technological factors of the rolling process on the intensity of the rolling out of the defect to determine the value of deformation and the coefficient of use of the plasticity resource. Introduced the notion of residual coefficient of plasticity resource in the second stage of transformation of the defect. Found that the causes of deterioration of the quality of cold-rolled sheet can be numerous defects of mechanical origin, caused by mechanical damage of the sheet surface. Conducted an analysis of profiles rolling modes, rolled on the mill 1700. With the use of existing methods calculated DUPR on workshop modes of rolling of specified profiles with and without considering the surface defects. Carried an optimization of the modes of strip rolling with surface defects.

Abstract:

The purpose of the present work is to research the process of hardening clinkerless slag-alkaline binder materials during the early stage of interaction between the ground granulated blast-furnace slag and the alkaline component by the thermokinetic method. The amount of heat emitted during the interaction between slag and alkaline component, and the influence of the duration of slag pre-hydration period upon this process have been assessed. These values were compared to similar values for binder materials based on portland cement. It was shown that ageing has significantly larger influence on heat emission during hydration of portland cement and on concrete strength.
We have elaborated in more detail the mechanism of hydration reaction of slag-alkaline binder materials starting at the level of active centers on the surface in accordance with the process of self-decelerating forming of crystallization centers. As slag grains are covered with a layer of hydrates, kinetics of hydration till the end of reaction is regulated by the process of diffusion that depends on the degree of structural irregularity.

Abstract: This paper describes an automatic line detection system which is based on mechanical vision technology to detect the defects of the nitrile gloves’ surface, and mainly discusses the extraction methods and the recognition algorithms about the gloves image features. Finally, the last part gives the methods to design an easy-operation, friendly-interface, full-functions interface software system. The automatic line detection system about nitrile gloves surface defects not only lets the gloves detection line to be automated, but also improves the production efficiency and the quality of the products.

Abstract: Precision steel ball is one of the most critical components for rolling transmission. As precision ball affects the performance of precision transmission system, fully inspection of these balls is an urgent need for the industry. This paper is to develop a real-time inspection system for surface defects of precision steel ball with fast and robust method and mechanism. The developed system consists of an optical measurement module as well as a mechanism module for full surface inspecting of the steel ball. The minimum defect and area can be detected by the developed system are 0.1mm and 0.01 mm2 respectively. The developed system has been testified against the designed specifications at speed higher than 3pc/sec and less than 0.5% missing rate. It verified the resolution, accuracy and robustness of the developed system which is capable for final defect inspection of steel balls for grade 100 bearing.

Abstract: This paper proposed a new method of surface defect detection of rolling element based on computer vision, which adopted CCD digital camera as image sensor, and used digital image processing techniques to defect the surface defects of rolling element. The main steps include collect image, use an improved median filter to reduce the noise, increase or decrease the exposure to achieve the image enhancement, create a binary image with threshold method and detect the edge of the image, and use subtraction method for surface defects identification. The experiment indicates that the above methods the advantages of simple, the capability of noise resistance, high speed processing and better real-time.