Solid State Phenomena Vol. 223

Abstract: Increased wear of drive wheel teeth in a longwall shearer requires frequent replacement of this expensive component, due to use of high power drives and geometrical limitations to the advance systems. A concept of the innovative Flextrack advance system, which enables limiting the high pressing stresses between cooperating surfaces of drive wheel and tooth gear (according to Hertz), was developed. The tooth gear, which consists of single segments, each with only one tooth, is the main component of Flextrack advance system. The sidewalls of the tooth gear have tacks of spherical shape located on the surfaces of the segments cooperating with each other. This design causes that the segments can be “seated” against each other, with no need to change the pitch between the teeth. The surfaces of tracks of tooth gear segments can incline transversely and longitudinally, and it is limited only by a special guide. The advance tooth gear system made in such way enables one to overcome horizontal and vertical inclinations of the conveyor route on which the shearer moves. The material model accepted for numerical analyses assumed the use of high strength spheroidal cast iron EN-GJS-1200-2 and L20HGSNM cast steel. The manufacture of casts of tooth gear segments in a precise casting technology enables one to obtain high accuracy of cooperating spherical surfaces as well as surfaces of the flank of the tooth cooperating with drive wheel. Accepted casting technology ensures high repeatability and the reduction of the cost of a single tooth gear segment, assuming serial manufacture. Changes applied to the design of advance system will increase the operational life of drive wheels, significantly reducing the maintenance time in very dangerous conditions.

Abstract: The new research trends are moving away from research works that are not directly connected with industrial applications. The Integrated Computational Materials Engineering (ICME) is an excellent example of the relationship between scientific research and the industrial sector.As an example of the design development of construction of a suspension component, an overview of the changes of a welded part replaced with cast component is presented. The identification of boundary conditions and forces operating on the nodes of the suspension element allowed determining the critical areas in the existing welded construction. Then the new design of casting for high performance applications was developed. Analysis of the kinematics of the suspension components also revealed the need for changes in the design of the mounting points of the suspension components to reduce the maximum values ​​of forces and enforced moments. As a result of successive stages of the topology optimization of analysed cast, control arms with significantly lower values ​​of maximum stresses were obtained. The material conversion of welded part with high strength AlZnMgCu aluminium alloy allowed the reduction of the weight by 25% for the lower control arm and 30% for upper control arm.

Abstract: The article describes the technology of making thin-walled components and elastic by additive technology SLS using a polyamide powder PA 2200. The characteristics of the selected elements and the results of their strength tests are presented. The research focuses on the anisotropy of the materials in the various models. Printing processes were investigated on surfaces perpendicular and parallel to the axis of the model. Based on measurements of deformation, coefficients of elasticity, and the influence of selected parameters of the printing process, the accuracy of tested elements were determined. Comparing results of the research indicated that there is a significant influence of direction and printing process parameters on elastic properties. Research can be helpful in the future in the design process of elastic and thin-walled components such as springs and bellows.

Abstract: The paper presents the characteristics of the selected additive technologies SLS - selective laser sintering, 3D Printing - bonding of ceramic powders, PolyJet Matrix - photocuring polymer resins. Procedures and methods for preparing models in the above-mentioned technologies are discussed. The examples of models made during research are described. The solutions covered by the patent application are also presented.

Abstract: The article presents the application of computed tomography (CT) for the detection of internal material defects in roller bearing rings made of steel. The tests were conducted using a set of four rings with different defects created artificially by means of electric discharge machining. In each test ring, several defects of the same type could be observed; however, they differed in terms of their size and geometry. The defects analysed had the form of internal blind holes with axes transverse or parallel to the surface of the track of the bearing – internal blind rectangular holes, and through slits in the inner cylindrical surface. The tests were conducted using a “V|tome|x s” X-ray CT scanner (tomograph) by GE. The roentgenograms of test objects were taken and then reconstructed in 3D. Each defect was visualised in different section planes of a reconstructed ring. Selected defects were represented in a solid form, and the measurements were taken in order to determine their geometry and volume. The tests confirmed that CT can be used in studies on such internal material defects in roller bearing rings as subsurface voids. All artificially made model defects were detected.

Abstract: In this paper, the basic information about multi-agent systems is given. The authors propose robot control algorithms for managing virtual autonomous warehouses, where the task performed by the robots is transportation between specific locations in the warehouse and a number of distribution points. Algorithms control the work of a single robot, including the cooperation with other robots in the environment as well as collisions avoidance. Different routing algorithms are evaluated through simulations focusing on service time and waiting time of executing tasks. The impact of the proposed algorithms on energy consumption was also checked, since this is important for the working time between battery charges.

Abstract: Controlling and monitoring industrial processes are important elements that allow high quality tasks to be performed, thanks to discovering all anomalies in those processes and making rapid responses to emerging issues. Currently, the most commonly used approaches are distributed systems, which consist of intelligent modules (motes) whose tasks are to collect the information, analyse it and perform the correct actions. Those modules are commonly cooperating with each other by exchanging the information using a network connecting those elements. For passing the information in distributed systems, wireless motes can be used which work in the ISM band. In the presented article, the authors show the results of the examination of the proposed routing protocols, which were implemented in the simulation environment. Each of the protocols has been tested for purposes of the quality parameters. The determinant of the quality parameter is the probability of the correctly received information by the motes of the exemplary distributed system.

Abstract: The article discusses the use of thermography in verification tests of a prototype calorimeter chamber constituting a part of a test stand for actuators used in smoke and ventilation systems. Based on the prototype control methodology developed at the ITeE – PIB, the authors identified areas posing a potential threat to the proper functioning of the system. The measurements of the temperature distribution on the outer surface of the chamber in the identified areas (trouble spots) are shown. The measurements were taken in thermal conditions related to tests conducted in compliance with the procedures of normative environmental investigations. The article also discusses the scope of activities that need to be taken in order to eliminate the adverse effects of heat transfer (thermal bridges, welds, etc.). Based on the thermographic tests, the authors proposed some guidelines to be included in the knowledge base used in the design of similar systems.

Abstract: The article presents the influence of the distance between a measuring head and a tested object on the results of eddy current defectoscopy test. The tests were conducted on the two inner rings of a tapered roller bearing where the test defects were performed. A one-millimetre hole corresponded to the surface defect. Internal blind holes in the shape of a rectangle corresponded to a subsurface defect. The research was performed with the use of a SSEC III PC defectoscope connected to a mobile PC. The measuring device is part of the system for the automatic quality control of bearing rings. The test was conducted for a slit having following dimensions: 0.1, 0.2, 0.3, 0.4, and 0.5 mm. The obtained characteristics are the composition of the pulse caused by the detected defect and the sine wave caused by the axial runout of the tested bearing ring. The correlation between the slit size and the value of the signal of the defect and the sine wave caused by axial runout of the tested ring was observed. The concept of “a coefficient of defect detection” was introduced. The described coefficient is a quotient of the value of the defect signal and the peak-to-peak value of the sine wave caused by axial runout of the tested bearing ring. The increase in the dimensions of the slit from 0.1 to 0.5 mm causes a 35 - 50% decrease in the coefficient of defect detection, depending on the test defect. A handle was designed to ensure a constant pressure of measuring head on the tested surface was proposed.

Abstract: The FSW method is a modern and still not very common method for joining materials by mixing them after plasticising with a special tool. The rotary motion of the tool and its pressure against the welded surface causes friction and, as an effect, local heating of the material that then causes plasticisation. Then the tool moves linearly along the trajectory of welding, while the stem causes the mixing of materials and tool’s shoulder concentrates and presses the material in the produced weld. An important feature of the process is that the material does not pass to the liquid phase and remain in the solid phase. This method allows the combination of non-welding and difficult to weld materials, including combining different materials (dissimilar). The FSW method is a new method and there are no tools to assess the quality of the process, especially on-line, that is in the making of the weld. Currently, the research methods used include point temperature measurement and measurement of forces on the tool performed during welding, and metallographic methods that are destructive can be used after the weld. This article presents the authors’ method for monitoring the Friction Stir Welding (FSW) processes with use of a multi-spectral vision method. The monitoring method uses the system built of two visual channels that work in different light bands; hence, the name of the method is multi-spectral. The main component of the system is an infrared camera that is used for the observation of the temperature distribution on the surface of the welded materials. The second visual channel uses the line-scan visual band camera for recording the image of the surface of the weld. Such observation allows the detection of weld defects and non-compliances, which include excessive burrs, discontinuities, uneven edge of the weld, as well as the subsurface faults such as cavities and sub-surface discontinuities. In addition, the temperature of the process is monitored to prevent under-and over-heating, which may result in a weak joint or cracks in the material. The presented method is applied for monitoring the FSW process and presents a worldwide novelty.