Mating Parts Research Articles

Assessing the Critical Factors Leading to the Failure of the Industrial Pressure Relief Valve Through a Hybrid MCDM-FMEA Approach

Industrial pressure relief valves must function reliably and effectively to protect pressurized systems from excessive pressure conditions. These valves are essential safety devices that act as cushions to protect piping systems, equipment, and vessels from the risks of high pressure, which can cause damage or even explosions. The objectives of this study were to minimize valve failures, decrease the number of rejected valves in the production line, and enhance the overall quality of pressure relief valves. This work introduces an integrated quality improvement methodology known as the hybrid multi-criteria decision-making (MCDM)—failure mode and effects analysis (FMEA) approach. This approach is based on prioritizing crucial factors for any failure modes in the industrial setting. The presented case study demonstrates the application of a hybrid approach for identifying the fundamental causes of industrial pressure relief valve failure modes and malfunctions. This investigation highlights the applicability of FMEA as a methodology for determining causes and executing remedial actions to keep failures from happening again. FMEA helps uncover the underlying causes of industrial pressure relief valve failures, while the integration of the hybrid MCDM methodology enables the application of four integrated MCDM methods to identify crucial factors. The adopted model addresses the shortcomings of the conventional FMEA by accurately analyzing the relationships between the risk factors and by utilizing several MCDM methods to rank failure modes. Following the application of the adopted methodology, it was discovered that the high-risk failure modes for the pressure relief valve included misalignment of wire, normal wear/aging, rejection of machined parts, mismatch of mating parts, and corrosion. Therefore, risk managers should prioritize developing improvement strategies for these five failure modes. Similarly, failures comprising debris, delayed valve opening, internal leakage, premature valve opening, and burr foreign particles were determined as second essential groups for improvement.

An Enriched Polyhedral-based Simulation for the Contact Modeling with Form Defects and Mechanical Loads

Contact modeling is an important activity in the geometrical and tolerancing management. The research on contact modeling using methods based on sets of constraints has focused on the stack-up functions or graph reductions for the accumulation of geometric variations. Even when the Skin Model paradigm is used to simulate form defects on mating surfaces, the impact of disregarding those defects has not been formally discriminated. In this paper, an enriched polyhedral-based approach for the contact modeling of mechanisms is proposed. The contact is simulated through a rigid body model with no frictional forces based on the screw theory. In this method, the external loadings on the mechanism are translated into an additional half-space in the polyhedron that imposes an additional restriction to the polyhedron operand. By explicitly including the external mechanical loadings, the impact of the form defects on a functional condition can be discriminated precisely. In this paper, a case study of a sliding contact between two mating parts of a spectrometer is presented to further illustrate the method advantages.

Machining-Induced Damage and Corrosion Behavior of Monel-400 Alloy Under Cryogenic Cooling Conditions: A Sustainable Initiative

AbstractMonel-400 is a nickel-based heat-resistant superalloy (HRSA) that is primarily used in oil and marine applications. Machining Monel-400 alloy for marine applications usually involves drilling and milling operations for assembly purposes, which should meet the requirements to withstand use in salt-water environments (i.e. lower surface finish to reduce corrosion and lack of burrs for tight sealing between mating parts). However, drilling of Monel-400 alloy can be challenging due to its high strength and density, which induces thermal effects that can influence the surface and geometrical integrity of the holes. Consequently, the use of environmentally friendly cooling technologies, such as cryogenics, is an excellent alternative to mitigate these effects, something which has not been widely investigated in the open literature when drilling Monel-400 alloy. Therefore, the current study aims to investigate the machinability of Monel-400 alloy under dry and cryogenic cooling conditions. The effects of cutting parameters and the use of a cryogenic liquid nitrogen bath on the surface integrity and corrosion resistance of holes were evaluated. Additionally, cutting forces, chip formation, and corrosion performance were analyzed. The results showed that the cutting forces increased by up to 8% under cryogenic cooling. Under cryogenic conditions, reduced elastic deformation resulted in a smaller chip size. Both cutting conditions produced a smooth surface finish with a roughness value of less than 0.2 µm. Corrosion resistance was reduced under cryogenic conditions at spindle speed of 5000 rpm. The current work showcases that cryogenic cooling is recommended for drilling Monel-400 alloy used in marine applications, but care should be taken in employing optimal cutting parameters to mitigate any effects on corrosion resistance.

Ремонт деталей авіаційних двигунів із жароміцних нікелевих сплавів із застосуванням адитивних плазмових технологій

In order to improve the maintainability of aircraft engine parts, the article examined the use of additive technologies in repairs. The article establishes that the use of additive technologies by the method of plasma surfacing in the repair of aircraft engine parts, such as turbine blades, sealing discs, NA parts, is very promising and will significantly increase the percentage of parts and assemblies restored after operation, which have a significant area of damage. Turbine blades are made of nickel heat-resistant alloys with a polycrystalline structure (ЖС6К-ВИ, ЖС6У-ВИ), or from alloys with directional crystallization (ЖС32-ВИ, ЖС26-ВИ). After operating for more than 6 thousand hours, in addition to the operational wear of the ends and side walls of the shroud flanges, thermal fatigue cracks up to 6 mm deep are observed on the blades received for repair. The technology of argon-arc surfacing and the surfacing materials existing for this process do not provide the heat-resistant properties of the restored surface necessary for the operation of the blades. The solution to the problem was achieved through the use of a compressed arc source with precision adjustment of the welding current and mechanization of the supply of filler material (powder), which would make it possible to surfacing with a limited penetration depth and, accordingly, mixing the deposited material with the base metal. The developed technology made it possible to restore damaged sections of blades after operation (shroud flanges, labyrinth scallops, z-shaped profiles and airfoil ends) on heat-resistant alloys using filler material equal to the strength of the base metal. For this process, powders of nickel and cobalt alloys with a fraction of +63...-160 microns are used, obtained by atomization with a jet of inert gas (argon). The main powders used are ЖС32-ВИ, ЖС6К-ВИ, В3К, Stellite 12, Stellite 6, ХТН61. Disc material – ЭП742-ИД. Working medium, air, oil and combustion products. The maximum heating temperature of labyrinth scallops is up to 680 ºC at a maximum medium pressure of up to 1.47 MPa. The maximum peripheral speed of the scallop end is 251 m/s. Material of seal mating parts ЭИ435 (cell δ = 0,1 mm). When developing the technology, the successful experience of restoring labyrinthine scallops of turbine blades was taken into account. The restoration of the labyrinthine ridges of the disk was carried out using a compressed arc source with precision control of the welding current and a robotic installation, which included a robot for moving the plasma torch and a manipulator for rotating the disk. This made it possible to carry out surfacing with a limited penetration depth and obtain a uniformly directed bead over the entire diameter of the disk. Testing of the restored disk in order to verify its performance was carried out as part of a run-in aircraft engine. To do this, after the next assembly of the run-in engine, the disk was installed in the MPT rotor. The test was carried out in 5 cycles, the duration of each cycle was 15 hours. No wear of the labyrinth ridges or cracks was detected. The functionality of the restored disk has been confirmed. NA parts are made of heat-resistant, low-aging, high-chromium nickel-based alloy ЭП648-ВИ. They operate in hot engine conditions at temperatures up to 900'C. As a result of operation, both end surfaces and flat surfaces in the tract area are subject to wear. To restore parts of the NA, the technology of additive growth by the method of microplasma powder surfacing was used. To confirm the operability of restored parts, a set of studies of samples grown using the same repair technology was conducted. At the same time, it was established that the chemical composition of the deposited metal corresponds to the requirements of the technical conditions-» the microstructure of the deposited metal after heat treatment corresponds to the normal heat-treated state of the alloy ЭП648-ВИ (ХН50ВМТЮБ-ВИ), the level of mechanical properties of the grown alloy with subsequent serial heat treatment (aging at 700ºC, exposure -16 hours) is not lower than the forging level used in serial production of the part.

OPERATION OF A SPIROID GEAR UNDER ELASTOHYDRODYNAMIC LUBRICATION CONDITIONS

Spiroid gears are used in the drive systems of various types of vehicles and devices. They are characterised by small overall dimensions and significant rotational speed reduction while maintaining the high positioning accuracy of the driven device. Spiroid gears require a lot of lubrication with oils, which separate the mating parts. In the case of spiroid gears, they separate the face wheel teeth and the worm thread. The resulting oil film reduces the coefficient of friction and lowers the temperature of the mating surfaces. The modelling of toothed rim lubrication is a complex problem. To separate the surface of the face wheel mating and the worm, one needs to consider the phenomena of fluid mechanics, heat transfer and tooth deformation. The formation of an elastohydrodynamic oil film of an appropriate height is determined by the type of oil, the mechanical properties of the worm and face wheel materials, relative speed, load and the geometry of the mating surfaces. The issues described in this paper significantly affect the correct operation of gears and have not yet been fully understood for spiroid gears. This paper presents the results of a study on the properties of the elastohydrodynamic oil film and describes its characteristics, with the unknown quantity being the rotational speed of the input shaft that ensures that the oil film separates the mating toothed rims. The calculation results were compared with those of other researchers. The obtained design recommendations can help designers improve the durability and reliability of spiroid gears.

IC Engine Belt Auto Tensioner-Field Failure Resolution

Failure of Auto tensioner was observed at engine of LCV segment vehicles. In this study both vehicle samples were analyzed to have a detailed investigation on the issue. In common, these failures can be caused due to assembly issues, adjacent parts incorrect mechanical parameters (belt tension, Arm movement, Angular vibration) and also by improper material selection etc. Issue was identified in pivot bush which is one of the sub assembly part in Auto tensioner. Where the bush material is with glass as a fillers in base polymer material of Nylon 66 matrix against the material specification on Nylon 66 with PTFE, MoS2 and Aramid as fillers. As glass is abrasive in nature eroded the mating part, hence caused the Auto tensioner system failure. This study revealed the failure is due to improper material composition of the pivot bush (sub assembly part) caused by raw material mix up at tier 2 supplier’s premises Keywords: IC Engine, Belt Auto Tensioner, Field Failure, Tear Down Analysis, SEM Analysis, ASTM D5630

What determines mate choices? Heterospecific mating in Sympetrum dragonflies

Abstract Heterospecific interactions are an important phenomenon of animal epigamic behaviour; however, they remain understudied within important groups, such as insects. Dragonflies are an ideal group for research on interspecific mating and possible hybridisation as they are easily identifiable, large insects, with a conspicuous mating process, often striking territorial behaviour and several mating systems. Using the genus Sympetrum as the model group, we examined heterospecific mating at three different levels. In the field, we identified whether species identity, time and weather affected heterospecific mating frequency. One important part of heterospecific mating is whether the process is completed. For dragonflies, this means that flying in tandem is followed by successful copulation, gamete fusion and oviposition (which comprise mating completeness). In a mesocosm experiment, we determined mating completeness (tandems, copulation, oviposition) of hetero‐ and homospecific pairs and the possible role of species density in heterospecific mating. In the laboratory, we compared the viability of the offspring from heterospecific pairs with different epigamous behaviour. We found heterospecific mating to be a relatively common phenomenon unaffected by environmental variables, that was primarily influenced by species identity, temporal distribution and abundance of dragonfly species. Consequently, the presence of counterparts of other species is the main predictor of the frequency of heterospecific mating. The probability of completed epigamic behaviour (copulation and subsequent oviposition) connected with gamete fusion is lower in heterospecific mating. Generally, based on our results we can assume that successful heterospecific mating (leading to gamete fusion) occurs in closely related species (e.g., Sympetrum striolatum and Sympetrum vulgatum). However, as pre‐copulatory barriers are not strongly developed in some dragonfly groups, less closely related species (e.g., Sympetrum sanguineum and S. striolatum) also may mate. This phenomenon requires further study as it may present a threat to the survival of some species in the context of changing environmental conditions, including climate change.

МЕТОДЫ МАГНИТНО-ИМПУЛЬСНОЙ СВАРКИ (ОБЗОР)

The article presents the features of various methods of pulsed welding in the solid phase using magnetic pressure according to a scheme with normal loading. A scheme of magnetic-pulse welding, implemented through electrical discharge cleaning without oblique impact, is described. Magnetic pressure is used for forming and welding. The authors proposed an original scheme for producing enclosing structures from dissimilar alloys by preheating the assembled unit in a vacuum, followed by crimping through the transmitting medium «shell» with an inductor according according to the «crimp» scheme. To obtain joints of the «rod-sheet» type in a heterogeneous combination of materials and structures of different thicknesses, the authors proposed to carry out a sequential connection of a magnetic hammer with the parts being welded, which allows synchronizing the process of thermal and force effects on the surfaces being welded. Various schemes for mating parts to be welded have been developed, including those using powder compositions as a connecting element. To implement the presented technological processes, universal special technological discharge-pulse equipment has been created, which makes it possible to implement the processes of welding, stamping, pressing, crimping, electric explosion of conductors and electrohydropulse processing of materials.

Improving the reliability of the turbocharger seal assembly by optimizing the elements of the seal assembly

Currently, most power units using internal combustion engines are equipped with turbocharging and that is explained by the requirements for efficiency, environmental safety and specific power characteristics. At the same time, the turbocompressor (TCR) is one of the resource-determining elements of power units, which accounts for a significant number of failures. Studies conducted towards the analysis of turbocompressor failures have shown that the main reason for it lies in a malfunction of the seal assembly, which is a consequence of extremely unfavorable conditions for its operation, consisting in a high (up to 800 оС) exhaust temperature, aggressive environment, a high (up to 120.000 min-1) rotor speed, the sliding speeds of the mating parts, up to 150 m/s. Oil for lubrication and cooling of the TCR is supplied through floating plain bearings, while the cavities of the turbine and compressor are isolated by means of the seal assemblies. Violation of their operability leads to the ingress of oil in a cavity of the impellers, to the imbalance of a rotor and, ultimately, to a turbocompressor failure. The determining factor affecting the operability of the seal assembly is a heat density of its parts. This factor is especially manifested in operating under forced conditions and engine shutdown, when cooling of a turbine volute is stopped by blown air, and a bearing assembly is stopped by circulating oil. In this case, a large part of the thermal energy is transferred from a heated turbine volute to the seal assembly and to the bearing assembly. The focus is on the temperature influence on performance of the turbocompressors’ sealing rings.

Geometry perception and motion planning in robotic assembly based on semantic segmentation and point clouds reconstruction

The assembly operations for robots in unstructured environments face tasks with generalized geometric information. The most essential issue for geometry perception is to estimate the relative pose between mating parts and then plan the corresponding actions. Current perception methods mainly focus on template matching of specific parts, which is still lacking in geometric generalization. To enhance the perception generalization ability, we propose an operation framework combining geometry perception and motion planning for robotic assembly manipulation. Semantic segmentation embodies a strong generalization capacity in image processing, which we utilized to extract the geometric features of assembly parts. The networks are trained via a self-made peg-hole image dataset. To reduce the measurement noise, the virtual point clouds for the peg and hole section are reconstructed with semantic mask and camera image principle, and a uniformization algorithm is adopted to raise the quality of the point clouds. The registration is utilized with the noise-free, uniform virtual point clouds, and the relative pose between two mating parts can be estimated more precisely. Also, the sequence of interactive geometry perception actions is defined. The performance of our framework is validated on assembly experiments, including different geometries in and out of our dataset. The results show that the framework proposed in this paper can perceive the generalization of geometry features for assembly parts, and leads to intelligent robotic assembly.

An Optimization Method for Improving the Accuracy of Multiple Parametric Printed Parts in FDM

Dimensional accuracy is one of the main key features for achieving the desired fit in fused deposition modeling (FDM). Printer tolerance and build orientation are the main challenges faced during the prototyping phase and hence there is a need for a method to calibrate the printer and the material being used that can serve as a guide to designing the clearances of mating parts. This paper presents the design and validation of a tolerance prototype and the study, which, with some analysis and data representation, gives the optimal solution. Hence, this can be used to compensate for the variations in dimensions while printing. A tolerance prototype model consisting of squares and circles of various dimensions is developed in Siemens NX 11.0 that tests the printer in three different orientations i.e., x-axis, y-axis and z-axis. FDM printers Accucraft i250 (heat bed type) and Flashforge (non-heat bed type) are used to print the prototype. The dimensions are measured with calipers to arrive at the dimensional correction templates that are further used to design and validate movable components.

Tribological behavior of diamond coated reaction-bonded silicon carbide under dry and seawater environment

Ceramic seal materials such as Silicon carbide (SiC) and Reaction-Bonded SiC (89%SiC and 11 % free Silicon) are widely used in mechanical pumps, compressors, and feed water pumps to prevent the fluid leakage between the two rotating shafts. In a continuously harsh environment, these mechanical seal materials undergo high friction and wear due to the high asperity-to-asperity contact between the two mating parts and generate high frictional heat at the interface. This scenario induces seal failure under high operating conditions. Especially in corrosive mediums such as acids, high pH value solutions, and hard abrasive media can cause aggressive seal failure. To reduce production downtime and improve the longevity of the mechanical seal, the surface of the seal material needs to be engineered with a suitable coating that will satisfy the required properties of high hardness, chemically inertness, and low friction coefficient. In this regard, we have come up with a super hard coating material such as diamond (Micro-crystalline) on the surface of Reaction-Bonded SiC using the hot filament CVD (HFCVD) method to meet the above-required properties. In this work, we have carried out a systematic study on the tribological effect of uncoated, and diamond-coated seal material against silicon nitride ceramic under a dry and seawater environment. The initial physical characteristics such as surface morphology, surface roughness, and Raman analysis were performed on the samples before and after coating. To understand the friction and wear characteristics, the linear reciprocating tribometer test (Ball on Flat) was conducted on the uncoated and diamond-coated samples using a universal tribometer for an operating period of 36,000 cycles. The experimental results show that the diamond-coated sample exhibits a low friction coefficient (0.05 ± 0.01) compared to the uncoated sample (Friction coefficient (CoF) = 0.24 ± 0.037) at a normal load of 10 N with a frequency of 10 Hz under a seawater environment. Similarly, under dry conditions for the same tribo-test parameters, the diamond-coated sample (CoF = 0.06 ± 0.02) outperforms compared with the uncoated sample (CoF = 0.42 ± 0.17) at a percentage improvement of 85 %. From the observed results, we conclude that diamond-coated ceramic seals are considered a suitable alternative to commercially available seals in terms of high operating conditions and durability under both wet (seawater) and dry running operations.

CONCEPTUAL FOUNDATIONS OF DISCRETE-CONTINUOUS STRENGTHENING OF ENGINE AND TURBO-EXPANDER COMPONENTS

The article focuses on design and technological measures aimed at ensuring improved technological characteristics of engines and turboexpander units. In particular, an improved concept of the technology of discrete-continuous strengthening of structural elements has been developed. This concept combines design and technological measures in a single technical solution. This expanded parameter space ensures greater efficiency of the final synthesised solution. For example, by analysing the stress-strain state of a representative fragment of contacting structural parts, the regularities of the influence of design and technological parameters on strength characteristics are determined: sets of parameters that provide increased strength of contacting parts and their durability are substantiated. Friction in the mating of parts is also reduced. In addition, the efficiency of the mechanism, which includes the contacting parts subjected to hardening, increases. The result is an increase in the technological characteristics of engines, turbo-expander units and other machines whose parts are subjected to discrete-continuous hardening. In general, the developed concept is aimed at a major enhancement of the service characteristics of structural elements. This is stated in the objective functions. These objective functions are minimized or maximized in the extended parametric space. A parametric model of the stress-strain state of a fragment of discrete-continuous reinforced bodies is created. This model makes it possible to study the impact of project and technological parameters and tribomechanical properties of contacting bodies. By purposefully varying the properties of materials, the shape and size of the zones of discrete and continuous strengthening, it is possible to achieve increased tribomechanical characteristics of a pair of contacting bodies.

Large deformation analysis of a backside-supported snap-fit with nonlinear behavior

In this study, the large deformation of a backside-supported snap-fit was analyzed. The backside snap-fit pair consisted of mating part and base part. The mating part was a simple cantilever, and the base part had an opening with a supporting bar. The reaction force of the supporting bar was found to be an important parameter for the assembly and separation of the snap-fit. During our analysis, the supporting bar experienced a large deformation with nonlinear elasticity or plastic damage. Finite element analysis was performed. Stress concentration was observed at the root of the supporting bar and at the bent edge of the base part. Three types of specimens were designed and fabricated for experimental verification. The first specimen was a reference design that was fabricated according to the same design concept as the actual product. The second specimen was designed to reduce the stress concentration. The third specimen had an enriched design to increase the supporting force. The reaction force corresponding to the applied displacement was measured using a testing machine. The load exhibited a highly nonlinear behavior and reached a maximum peak value without causing any apparent damage, after which it decreased with plastic damage. Through numerical and experimental analyses, it was found out that the design of the backside-supported snap-fit could be improved by reducing the stress concentration and increasing the stiffness of the supporting bar.

A TAGUCHI-TOPSIS HYBRID TECHNIQUE TO ENHANCE THE FRETTING WEAR CHARACTERISTICS FOR SiC AND SILICA-ENRICHED BLA-REINFORCED AZ91D Mg ALLOY-BASED MMCs

This investigation intends to come up with a cost-efficient and easily available bamboo leaf ash (BLA) which has high content of Silica, as an effective and complimenting reinforcement for the production of magnesium alloy-based metal matrix composites. By incorporating SiC and BLA reinforcement to AZ91D Mg alloy, the composites were made using the bottom pouring stir casting technique. The ratio between SiC and BLA in the composite, respectively, varied as 0:0, 6:0, 0:6, 4:2, 3:3, 2:4 wt.%. Fretting wear is one of the fundamental modes of wear for any mating parts which have vibration with low amplitude. In this study, an integrated Taguchi-TOPSIS is adapted to make the process variables more optimal for fretting wear of composites. Material composition, load, temperature, time, frequency and stroke length are selected as process parameters. The objective is to minimize the coefficient of friction, volume loss and surface roughness. Using the TOPSIS approach, the multi-criteria optimization approach was reduced to a single-criteria issue. The results revealed AZ91D/2 wt.% SiC/4 wt.% BLA, 10N, room temperature, 30-min, 30 Hz and 0.7 mm stroke as optimal parameters. Microscopic study demonstrates that fretting wear occurs in the partial slip zone for the composite tested at optimal condition. With temperature, the wear regime in composites shifts from partial slip to mixed fretting, whereas in alloys, the wear regime shifts from mixed fretting to gross slip. When the correct set of circumstances are available, hybrid composite can function well as a replacement for traditional materials in machineries vulnerable to fretting wear.

Intelligent assembly modeling of complex product based on cognition of interaction structures

Interactions of a part with other parts in an assembly constitute the behavior of the part. However, currently parts interact with each other lifelessly in assembly environment due to their incapability of cognizing interaction structures between them, making the assembly modeling of complex products suffer from considerable manual interventions. An intelligent assembly modeling method is proposed for complex products in this paper, by endowing parts with the ability of cognizing interaction structures between them. In this method, the concept of interaction feature pair (IFP) and the corresponding automatic construction algorithms are developed to explicitly describe interaction intent (i.e., how a part will mate with other parts) in designer’s mind, providing carriers for part cognition behaviors and dynamical interaction intent in the assembly modeling process. On this basis, an object-oriented product information model considering IFP is established to facilitate the complete capture of interaction intent at part modeling stage and the consistent transmission of it to assembly modeling stage, endowing parts with the cognition ability of foreseeing how to mate with other parts before and after loading into assembly modeling environment. Then, IFP matching algorithms are designed to support the part cognition behaviors of actively cognizing interaction structures, perceiving potential mating parts and mating with other parts with high efficiency. Assembly modeling case studies of a reducer and a Mecanum wheel with few manual interventions indicate the feasibility of the proposed approach.

Regulation of tolerances of associated parts of mechanisms of livestock farms during repair

The paper considers an algorithm for optimizing the efficient distribution of resources that determine the cost of assembly work, subject to restrictions that ensure high quality assembly of livestock machines and equipment. To determine the required tolerance values for parts, one can use the known methods of parametric optimization. Therefore, the application to the solution of the problem of the method of Lagrangian multipliers as a result of the calculations obtained the optimal tolerances of the details of the angle. Upon completion of the calculations, the optimal assembly parameters of the node for various values are obtained; the result is presented in graphical form. There are various methods for calculating component tolerances of mating parts. Methods based on the statistical evaluation of tolerances and finding their root-mean-square deviations make it possible to reduce the degree of risk when expanding the tolerance limits for mating parts and reduce assembly losses. The correct assignment of tolerances allows one to achieve significant savings in material resources and reduce production costs. The most effective solutions may be those obtained by implementing optimization procedures that ensure the minimization of the quality criterion under the conditions of restrictions determined by the components of the assembly assembly process.

Experimental Study of the Thermal and Wear Characteristics of a Foil Bearing Lubricated with a Low-Boiling Liquid

Developing high-speed rotating machines, such as microturbines, requires new solutions for bearing systems. Foil bearings are one of the fastest-growing high-speed bearing technologies. This article presents the results of experimental studies on foil bearings conducted on a test rig reflecting the operating conditions of the target machine. The tested bearings were therefore placed in a chamber filled with a low-boiling medium used as a working fluid in vapour microturbines. The experiments were carried out for several test cycles following a repeatable procedure. To carry out the tests under specific environmental conditions, a measurement cycle according to the developed test procedure and a temperature stabilization system for long-term measurements were proposed. The research involved determining the thermal characteristics of four foil bearing variants and assessing the impact of operating conditions on their wear. Additional research has shown that the operating characteristics are highly dependent not only on the materials and geometry of the bearing but also on the surface roughness of the mating parts. This study is part of ongoing work to select appropriate designs and material packages for foil bearings operating under conditions involving lubricating film formation and heat dissipation.

Research of the deformability of the cantilever axis of the satellite of a multi-satellite planetary gear and its influence on the load distribution over power flows

A mathematical model of the axis of the satellite, cantilevered in the cheek of the carrier of the planetary gear, is presented. The axis of the satellite is presented in the form of a beam on an elastic base. The influence of the flexibility of the axle and the drive elements mated with it on the distribution of the load over power flows is considered. The Leibniz formulas and the Euler method were used to obtain the model. The coefficient of uneven load distribution over power flows is obtained by solving a system of displacement compatibility equations, including deformations of the wheel teeth, rolling bearing, satellite axle and mating parts, taking into account the initial non-adherence of the teeth due to gear manufacturing errors. The load capacity of a planetary gear with cantilever axes of satellites is analyzed depending on the number of power flows. Keywords: planetary gear, deformation, cantilever axle, load distribution. fplehanov@list.ru, alexandrsun4009@gmail.com

Assembly task execution using visual 3D surface reconstruction: An integrated approach to parts mating

This paper is focused on assembly tasks executed by an industrial robotic manipulator in the presence of uncertainties. The goal is to achieve higher levels of autonomy and flexibility of robotic systems in the execution of such tasks. In particular, as a well-established paradigm of assembly tasks, a Peg-in-Hole task has been considered, where the pose of the target object with respect to the robot is known with uncertainties far larger than the task tolerance, e.g., due to manual positioning of the object in the workcell. The proposed approach is based on the reconstruction of the object surface by means of a number of point clouds provided by a depth sensor. The reconstruction is then compared with a known CAD model of the surface, in order to localize the position and tilt of the holes. Finally, the peg insertion is performed in two steps: a search phase, in which the peg tip gently slides on the surface following a trajectory described by Lissajous functions, and a mechanical coupling phase, in which a compliant behavior is imposed to the peg. Experiments on a collaborative manipulator confirm that the proposed approach allows to achieve a better degree of autonomy and flexibility for a class of robotic tasks in partially structured environments.