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Nitriding is a technology that leads to an increase in the utility value of the product. It’s most im-portant benefits include increased corrosion resistance, abrasion resistance, wear resistance, increased resistance to fatigue failure under cyclic loading, and many others. The design of a suitable nitriding technology not only on the basis of empirics requires a closer study of the relationship between the structure of the nitriding layer, its properties and the course of a particular degradation process. Be-cause the life of most components is related to abrasion on the surface, the occurrence of fatigue cracks and corrosion effects, it is crucial to influence the mechanical and other properties in this sur-face area. High functional requirements are placed on the functional surfaces of steels for weapons production, which lead to a long service life, reliability and dependability of the components of the weapon system and its safe use. The paper discuss the influence of selected nitriding technologies on the mechanical properties of steel 42CrMo4 and 34CrNiMo6, especially on the hard and microhard-ness of surface layers, change of its structure and next to change the surface texture and dimension of component. The steels were nitrided in plasma and gas. Nitriding in gas led to more significant struc-tural changes in the surface layer of both steels compared to plasma nitriding.

The paper is focused on an analysis and optimization of the rotary draw benging process to eliminate bent tube ovality by modification of the pressure bar geometry. The bending process is realized on WafiosCNC bending machine. A tube that is bent for an automotive application is made of 34MnB5 steel. Currently, after tube bending process by an angle of 120°, an unacceptable ovality occurs. Therefore, it is necessary to improve the quality of production and thus prevent the formation of unacceptable ovality. In this case, the optimization of the pressure bar geometry is performed. For this reason, a numerical simulation using finite element method in ANSYS software is performed. Before the actual optimization, an accuracy of the simulation is verified by analysing of the current state and comparing it with simulation results.

The aim of this paper is an analysis of the dependability of critical components of the John Deer 7530 tractor. For this analysis data was used from a database which contains maintenance data of 166 trac-tors during approx 9 years. The first part of this article is devoted to the selection of critical compo-nents based on number of failures of individual machine parts for a given period and their sales pric-es. The next part of article presents data for calculation dependability indicators which contains oper-ating times to failure and operating times without failure. Due to the large size of the data files of the individual components, the data are only given for one machine component. Furthermore, the meth-od of calculation of dependability indicators is described by parametric statistical methods according to ČSN EN 61649:2009 and mean time to operating failure. The results of the analysis are summa-rized in tables and graphs. The method in this article can be used to optimise the maintenance pro-gram.

The laser welding method is one of the youngest but the most progressive welding methods. The advantages of laser welding include: simple automation combined with modern computer technolo-gy, very low heat input to the weld, high productivity, high welding accuracy and low noise during laser operation. In this work, the sample meltings were prepared in a protective atmosphere varying the welding parameters – laser power, welding speed, or focus position. A total of 12 samples were prepared this way. The aim was to evaluate the shape and depth of the melting of the material for selected values of parameters. Based on this metallographic evaluation, the optimal welding parame-ters were selected for a pair of austenitic stainless steel tubes (X2CrNi19-11 and X5CrNiMo17-12-2) for fiber laser welding. Macrostructure and microstructure evaluations, microhardness tests and tensile tests were performed on these welded samples.

The paper describes the course, conditions and results of the impact test of the supporting frame of the test station for dynamic tests of gears. The test station makes it possible to simulate different gears operating conditions. The basic support frame structure of the test station was evalu-ated as unsufficient based on the results of measurement and processing of the measured low and high fre-quency vibration values in the verification series of experimental tests. The basic failure of the origi-nal design were the significant resonance actions that were the results of the dominant sources of vibration being near the natural frequencies of the vertical and horizontal beams of the test station base. A structural design of the test station supporting frame was designed and implemented. The goal was to increase the rigidity of the frame and eliminate unwanted resonance phenomena. The impact tests were used to determine the values of the natural frequencies of the most stressed parts of the supporting structure - vertical and horizontal beams, before and after implementation of struc-tural modifications. The comparability of the impact test results was determined by adherence to identical measurement conditions.

The paper derives mathematical and ggraphical relationships between technological parameters and result of metalworking, in the application of progresive cutting materials based on coated cutting tools of sintered carbide and cutting ceramits. The development of new cutting and machined materials leads to new perspectives on their interaction in the machining process. This process leads to patterns between cutting conditions and machined results. These need to be defined and used in favor of efficient machining of mechanical components in practice.

In this paper, innovative resistance element welding (REW) technology for joining galvanized steel sheets to thermoplastics (PMMA) is introduced. The essence of the innovation is in the use of a special bimetallic joining element consisting of the core made of a Sn60Pb solder, and the sleeve made of a Cu tube. During resistance heating, the solder melts, thus allowing the formation of a metallurgical joint with galvanized steel sheet. Since Sn60Pb solder melting occurs at temperatures (from 183 to 190 °C) be-low the thermal decomposition temperature of most thermoplastics (for PMMA above 300 °C), there is no thermal destruction of the PMMA material around the joint. The mechanical fixation of the thermo-plastic material at the overlap joint is provided by the sleeve made of Cu tube which has a substantially higher strength than a Sn60Pb solder.

The current study investigates the influence of the dressing process of the vitrified bonded microcrystal alumina grinding wheel on the roughness of the machined surfaces in cylindrical grinding of Ti6Al4V alloy using different types of stationary diamond dressing tools. For the research, four types of dressers were selected, which differ from each other by number, size and location of diamond cutting elements. Each dresser has been tested at four different dressing feed values with the same dressing depth. Two sets of experiments were conducted to determine the tendency of grinded parts roughness parameters change depending on the dressing feed for each type of diamond dressing tool at two values of grinding feed. A comparative analysis was carried out to show the dressing feed influence and the effect of the diamond dresser type select on the roughness parameters of the grinded surfaces.

With the rapid development of modern manufacturing technology, people have higher and higher requirements for the quality of mechanical products, and the precision of machine tools for processing mechanical products has gradually increased. Therefore, the development of static pressure guides is particularly important for precision processing industries. The load on the guide rail has an important effect on the thickness of the oil film, and the stability of the oil film thickness directly determines the accuracy of processing. In order to obtain the best control method for the thickness of the oil film, the dimensions of the hydrostatic guide rails and the three-dimensional model of the guide rails were designed and calculated in this paper, and the fuel supply method of the guide rails was determined. The simulation model of the oil film was established and imported from the AMESim software into the FLUENT software to obtain the pressure, velocity, and temperature distribution maps of the oil film. And the pressure distribution data was processed after summarizing. Combined with the relevant mathematical models, the mathematical model of the oil film thickness was finally obtained. Then the Simulink software was used to analyze and the PID control was introduced for comparative analysis. The DOB anti-interference control theory was introduced, and the anti-interference control algorithm was improved. The anti-interference algorithm adapted to the oil film thickness control complete the programming of the modules of the interference controller. The anti-interference control section was created in the Simulink software, and the system of the DOB module was finally completed after packaging. In order to verify the method in t his paper, a static pressure rail test bench was set up, and relevant detection tests were completed. The results of the above studies showed that the control performance was greatly improved after introducing the anti-interference algorithm adapted to the oil film control system.

This experiment assesses the suitability of square-welding high strength steel using the deep penetra-tion welding method, RapidWeld. The aim of this method suitability assessment was to compare the final material properties of three welds, welded accordingly to identical welding procedures. High strength, ultra-fine-grain steel S1100QL (XABO 1100) was used as a parent metal. The suitability con-firmation was based on the achievement of requested mechanical properties of ISO 15614-1 and mo-bile crane manufactures standards. The hardness, strength properties and impact energy measure-ment and evaluatioon of the joint was performed during the experiment. The joint was welded re-peatedly with the use of the same welding parameters for the confirmation of process stability. The achieved mechanical properties fulfill all the requirements. The hardness value deviation is caused by different properties in the heat affected zone. The root cause of the impact energy deviaton was not fully investigated, but the minimal measured values are above requirement. The deviation of the strength characteristics is mininal. The performed experiment has confirmed that the selected weld-ing method is suitable to ensure that the requested material properties of welded high strength, ultra-fine-grained steel are achieved.

The article deals with the use of SPC tools to manage and improve the machining process - drilling furniture elements. The content of the article is to use such SPC tools as basic statistical parameters, box plot, histogram, classic and special control charts, and process capability indicators to assess the drill-ing process and to indicate areas to improve. The article indicates the power of SPC tools in woodwork furniture process control and power of using the Statistica program from TIBCO Software Inc. in this area. SPC tools bring a lot of important and useful information about the analyzed drilling process, its weaknesses, which contributes to the improvement of the process. The conducted study has been shown that the tested drilling process requires improvements, in particular in the area related to the machine and man. The activities that should be implemented to improve the quality of the process were defined, including implementation of the Poka-Yoke system, development of a maintenance inspection schedule, a visual manual for machine setup, employee training with a verification exam, introduction of an employee's suggestion system, modification of the company's motivation system. SPC tools helped to identify the source of process problems, defined a process’s stability and capability to meet a customer requirement, and assist with other insights, that were used to define improvement action.

This paper investigates the replacement of a conventional steel coil spring with a composite disc spring with the aim of minimizing its weight. Simulation in the CAD system Siemens NX 12 was used to determine the composite disc spring’s behavior. The regression functions were stated based on the numerical simulation. Based on the regression functions the solution with the minimum weight was found using software programmed in Matlab. The prototype discs were manufactured from carbon fibre prepreg. Their load-deflection characteristics were tested and compared with the designed values. The experimental results show that using this solution reduces the weight by about 30% in this case.

Deflection of cutting tools under the action of cutting forces has a significant influence on the error of machined surface and the stability of cutting process. Considering the complex geometric structure of cutting tools lead to higher calculation accuracy of the tool deflection analysis. Therefore, CAD models of double-sided solid ball end mill and helical drill bit was created in this study. The impact of tool material and clamping of the tool under the influence of cutting forces individually in three axes was obtained via finite element analysis. An error of the numerical model was less than 7.2% and has been validated by analytical calculation. Geometric errors in the case of die and mold manufacturing are provided below or close to 0.02 mm. However, due to the force effect of the cutting process it is not recommended to use HSS tools as the analysis confirmed. Stiffness of sintered carbide tools was more than doubled.

Burnishing is a cold working process with superficial plastic deformation, which is to exert an external pressure through a very hard and smooth roller or ball on a surface to occur a uniform and work-hardened surface, to make it possible to reduce roughness, to increase the hardness and to produce residual stresses of compression. The unalloyed S 355 J0 steel specimens were machined on a conventional lathe to the proper dimensions; these machined specimens were then burnished by a simple locally designed and fabricated roller-burnishing tool. The main objective in this work is to determine a mathematical models statistically based on experimental design (response surface methodology) using central composite second-order rotatable design which allows to give the relationship between the two out parameters surface roughness and hardness, representative of the superficial layer surface caused by the four internal roller-burnishing parameters called: burnishing speed, force, feed and number of passes of the tool. The experimental results indicate that feed, burnishing force and speed are the most important and significant parameters to improve roughness surface, and feed, speed, burnishing force and number of passes are the most important and significant parameters to improve superficial hardness of S 355 J0 steel specimens. The surface roughness and hardness were improved from about 2.5μm to 0.15μm and from 176 HV to 226 HV respectively. The validated models with coefficient of determination R2 = 93.1% for surface roughness and R2 = 89.8% for hardness, seem correlate well with the experimental results.

On the base of a well-known method of machining with disk-shaped rotating tool the self-propelled tool was designed. The principle is based on braking the tool rotation during machining, until the moment of determined wear criterion on the tool flank. As with the growth of tool wear the force of cutting resistance increases, it is possible to use it for automatic tool swinging into a new position by which a new part of cutting edge comes into engagement. The paper describes the tool design, theoretical analysis of Rz after machining and actual experimental machining results.

Main aim of this paper is to analyze the thermal behavior of different cooling channels and to describe advantages of manufacturing of a mold with these channels using a 3D printer instead of drilling machines. This work was primarily done by the usage of virtual simulation. Validation of thermal simulations was performed by usage of simple analytical solution. A simple model of molded brick was designed to analyze the cooling time and the temperature distribution in the mold when changing the cross section of the cooling channels. Three types of different rectangular cross-sections and one circular were chosen. All of them have the same area. The cooling channel with circular cross section was positioned closer to the part in next design and influence of this change was analyzed. Last tested configuration is conformal cooling channel with a channel path twice longer. It is obvious, that most suitable configuration of cooling channels is combination of conformal design with rectangular shape as close as possible to plastic part.

The article deals with the wave propagation in thin plate. A wave was caused by the impact force. In the first part of an article the Kirchhoff's theory of thin isotropic plate is given. It is a vertical displacement w, angles of rotation tangent φx and φy, bending stresses σx, σy, shear strength τyx = τyx, shear strength from displacement forces τxz, τyz. In the second part of an article is solved a Kirchhoff's theory by analytically in MATLAB programme. Analytically were solved only displacements u, v and velocity u ̇,v̇ . The solution is performed for two plate materials - aluminium and steel. By result are deformations and velocities graphs in the x-axis and the y-axis at the measurements points given. In the conclusion of an article is comparing of individual deformations and velocities graphs.

The quest for light and stiff structures by industries such as the medical industry and the aerospace industry is the driving force behind developments in additive manufacturing technology. One way to achieve significant weight reduction of components is by deploying periodic porous structures. Various types of porous structure geometries use material with varying efficiency, and therefore vary in their resulting mechanical and physical properties. This article focuses on the lightweight Schoen Gyroid cellular structure, which could offer a suitable combination of the desired mechanical properties. The goal is to determine the effect of the volume fraction on the load capacity of the gyroid structure made of maraging steel using DMLS technology. We conclude from the experimental measurements that the results could be affected by several factors, which are detailed at the end of article.

The paper deals with design proposal of a cover part of a strength bumper, which is tasked with creating the outer design lines of an automobile without sharp edges according to legislation in force and also with protecting a vehicle against damage. The cover part serves for covering the strength part of a back strength bumper, which will be equipped with a winch and used in off-road vehicle Nissan Patrol Y61. Another aim is to perform a FEM analysis of the strength part of the bumper loaded by towing force of the winch and thus to verify a safety of the structure. The next solution of the issue will be an approach to real testing, which will verify a correctness of a numerical computations and also fulfilment of the purpose of creating the structure. Bases of FEM analysis and practical experimental verifications of the structure will be also used as a background for granting approvals, certifications and type approval by superior authorities.

The use of a new method of attaching fixed blades to a stator disc led to the need for evaluating the strength of a riveted joint. Conventional mechanical testing revealed large variations in the strength of this joint. After sectioning the joint, it was found that the shank did not fill completely the hole in the shroud of the disc. Further investigation involved numerical simulations using the DEFORM software, because securing additional samples for physical examination was complicated. The first simulation task focused on determining the tearing-out force, taking into account work hardening of the shank material due to plastic deformation. The second simulation task aimed to identify optimum initial dimensions of the shank. The goal was to ensure that the rotary upsetting process causes the shank to completely fill the hole in the shroud. As a result, the joint strength would be improved and, above all, the variation in strength eliminated.

Four different heating temperatures in the range of 770 °C - 950 °C were used for laboratory heat treatment of low carbon low alloyed steel. Chemical composition of the steel was based on the most common TRIP steel concept, only the silicon content was lowered to 0.6% and it was partially replaced by 1.4 % of aluminium. The steel was further micro-alloyed by niobium. Two different ways of cooling were applied to the samples. The first set was cooled to 425 °C in a salt bath with the temperature of 200 °C, the second set was cooled to 425 °C in a salt bath heated to the temperature of 400 °C. In this way, two distinctive cooling rates were achieved for every soaking temperature. Once the samples reached 4250 °C, they were in all cases removed to the furnace for 20 minute hold at the temperature of 425 °C. The final cooling was carried out in air. Resulting microstructures were analysed by scanning electron microscopy and consisted of various amounts of ferrite, bainite and retained austenite. Tensile strength in the range of 750 - 908 MPa was obtained with total elongation of 33-42%.

Direct Metal Laser Sintering (DMLS) is a method of additive manufacturing (AM), which builds metal parts in a layer by layer procedure based on a CAD template. The melting of metal powder by an energy beam and successful mastering of the whole manufacturing procedure requires complex management. Physical and chemical metallurgical phenomena occur during melting of the material and the final microstructure depends on many factors. This study investigates the microstructure of struts depending on their distance from the building platform. It is known that metal powder does not allow the dissipation of heat in the same way as molten material due to gas interstitial volume between the spherical particles. Metallography and micro-hardness were investigated on maraging steel 1.2709. Different melting strategies are recognizable in the macroscopic structure of metal alloys. Interesting facts have been discovered, for instance lose molten group or change of hardness depending on a shape of metal cells. In generally, significant differences were not found between individual specimens.

The article describes the course of a pressure test that was made to determine the maximum force in the case of breaking the integrity of the casting. Observation of the forks arm deformation can be done with using sensors on the universal tensile testing machine. Using a high-speed camera to monitor this test will provide results in digital form that can serve to further research. Subsequently, analysis of the material properties of the AlSi7Mn0.3 casting is described, using the methods of evaluation of mechanical and structural properties. Periodic tests check the castings status to ensure recurrent quality in order to achieve the required safety in accordance with the standards for road vehicles.

The forging industry, and the production of high-strength forged parts in particular, saw no substantial progress in recent decades. High-strength parts continued to be made of well-tried steel grades which meet the economic and environmental production requirements, using mainly the conventional quenching and tempering. However, the latest findings in physical metallurgy of higher-silicon steels suggest that high-strength forgings can also be obtained by producing bainitic and martensitic microstructures. The first are of the CFB (carbide-free bainite) type and the latter comprise the QP (quenching-partitioning) microstructure. At greatly reduced processing costs, properties comparable to tempered martensite can thus be attained.

Using innovative methods of heat treatment (HT) for high-strength steels, such as the Q&P process, very favourable ratios of ductility and strength can be achieved. Materials processed by this technology have higher content of retained austenite, and therefore better ductility. This experiment deals with HT of 42SiCr steel. The conventional HT and the Q&P processing are compared with respect to material properties. Metallographic analysis, hardness measurement, X-ray diffraction phase analysis (of retained austenite content) and tensile testing were performed. For the hardened samples, the effects of the cooling rate on their microstructure were assessed and the measured real-world data were compared with the simulations performed in the FEA simulation software DEFORMTM based on the thermocouple records. After a conventional HT, the material showed little sensitivity to the cooling rate. In contrast, the Q&P process with higher quenching temperatures resulted in a higher austenite content and elongation of up to 15 % at a strength of 1800 MPa.

The physics features of the cutting process of ultrafine-grained metals produced by the method of severe plastic deformation are considered. The aim of the research was to evaluate, whether the grain size of titanium alloy has an influence on the characterization of chips, the cutting force components, the surface roughness and the microhardness in the cutting process. The experimental data of the machineability of titanium alloy Ti-6Al-4Mo with sub microcrystalline structure are presented in the paper. The features of the chip formation, the changes of the chip ratio and the components of the cutting force are examined. The main characteristics of the cutting mechanics are calculated and based on the experimental values. Also the experimental values of the surface finish roughness and microhardness are shown. It is established, that the change in the structure of the metal has an ambiguous effect on machineability by cutting. Further investigation of the machineability of metals with a submicrocrystalline structure will allow to choose the efficient mechanical treatment.

This work deals with the problematics of cutting forces when drilling holes in Inconel 718. Drills with different geometries of cutting edge were used. The cutting forces and torques were measured during the experiment. The feed cutting force had the greatest influence of all the cutting forces, therefore only the cutting force feed was evaluated. The torque was monitored. This material is known for its unique properties of high strength at high temperatures, corrosion resistance, high hardness, work hardening and low thermal conductivity. Part of the paper is focused on the experiment where the effects of the geometry of the cutting edge on cutting forces are evaluated. This paper is limited only to carbide tools. The results of the experiment are compared with results from other research institute.

Middle carbon low alloyed steel 0.4C-0.6Mn-2Si was subjected to thermo-mechanical treatment typical for TRIP (transformation induced plasticity steels). The processing consisted from soaking at the temperatures of 850-1000 °C and cooling at 30 °C/s to various annealing holds in bainite transformation temperature interval of 350-500 °C. During the cooling from the soaking temperature, two compressive deformations were carried out, the second one always at 720 °C. Resulting microstructures were analysed using light and scanning electron microscopy. X-ray diffraction phase analysis was carried out to establish volume fraction of retained austenite and mechanical properties were measured by tensile test. Tensile strengths in the region of 847-963 MPa were obtained and very good total elongations of 30-40% were achieved at the same time. Multiphase microstructures were obtained with various amounts of ferrite, bainite, retained austenite and pearlite.

The paper presents the strength tests results of joints made by use of two hot melt adhesives. The tests were carried out according to the modified standard ČSN EN 1465 (66 8510) and ČSN EN 205 (66 8508). For bonding the three-layer plywood of 4 mm thickness was used. The test samples of 100 x 25 mm size were cut out from a semi-product in the direction of its longer side, in the oblique direction and in the direction of its shorter side. The specimen pairs were bonded using the hot melt glue gun. All assemblies were loaded up to their destruction. The destructive force and the destruction type were registered. From the results of carried out tests evaluation it follows that hot melt adhesives can be recommended for bonding plywood. The bonding strength of bonded joint is comparable to the strength of the bonded material. Finally the technical-economical evaluation of the experiments was carried out.

The paper deals with mathematical modelling of nuclear fuel rod (FR) vibration in TVSA-T fuel assembly induced by pressure pulsations of coolant. The FR is modelled as a system consisting of two subsystems - fuel rod cladding and fuel pellets stack - that can possibly impact-interact. Besides, the cladding subsystem can possibly loose contact with spacer grid cells that is another source of strong mechanical nonlinearities. The contact forces in all the contact points are represented by the force-velocity-displacement characteristics that include both normal and friction forces. The influence of coolant cross-flow is analysed using partitioned approach to fluid-structure interaction description. The qualitative change of FRs motion and the change of fretting wear of the FR cladding are shown.