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The research is aimed at determining the optimal shape of the inductor for processing the teeth of a large-sized gear wheel by magnetic pulse processing. The work studies the distribution of the magnetic field strength along the area of the wheel tooth, depending on the type of inductor. This is necessary in order to predict the distribution of changes in the metal structure caused by MIO and their effect on the wear resistance of the wheel. The main task of the research is to establish the dependence of the magnetic field strength indicators on the shape and length of the inductor. Identifying the need for the presence or absence of a core. Two types of inductors were considered: the first involute shape is worn on the wheel tooth, the second is located in the cavity between the wheel teeth. The calculation of the magnetic field strength distribution was carried out using the ANSYS Maxwel software package. As a result of the research, it was found that the most effective for conducting magnetic pulse processing is the inductor of the first type, which is worn on the wheel tooth. The average values of the magnetic field strength are 330-380 kA/m, which is sufficient for structural changes in the surface layer of the metal over the entire area of the working surface of the tooth. The inductor of the second type, the length of which corresponds to the width of the gear crown, is ineffective. Since the magnitude of the magnetic field strength generated by it in the working area of the wheel reaches only 29-67 kA/m and does not lead to structural changes in the surface layer of the metal. Increasing the length, as well as using cores of round and triangular shapes, did not give significant changes in the magnitude of the strength. It was also determined that the use of a shortened inductor of the second type is promising. In further studies of the optimal length of the inductor, it is recommended to study the direction and find out whether it is possible to process the gear wheel by stepwise movement of the inductor along the working surface of the tooth. [ABSTRACT FROM AUTHOR]

It is difficult to imagine modern mechanical engineering without timely and targeted improvement of technological processes, in connection with which new and enhanced traditional methods of manufacturing and processing various types of structures and parts are being developed. One of the ways to reduce the economic costs of machining gears made by traditional methods is the transition to the field of powder metallurgy - powder sintering. This paper presents the possibility of a local increase in the mechanical properties of gears made by powder sintering using laser processing. Laser processing was carried out on a robotic welding and heat strengthening complex, which includes a 6-axis industrial robot, a 2-axis welding positioner, a laser head and a 5 kV ytterbium fiber laser. The high porosity of the sintered material compared to cast billets is a factor limiting the possibility of using laser thermal hardening, as it increases the likelihood of melting the edges of the machined surfaces. The present work is aimed at solving this problem. Before carrying out the experiments, the main quality criteria were identified: “no melting” and “hardening depth”. In the course of a series of experiments on laser thermal hardening, it was possible to significantly increase the hardness of the samples (in the delivered state about 30 HRC), which after processing is in the range from 55 to 65 HRC with a depth of up to 2800 μm on gear teeth made of powder materials. However, open questions remain, which are resolved in performance testing, such as durability and wear.

Background. Modern gear hobbing machines design is based on mechatronic drives, which prompts questions about the influence of errors that occur in the main motion direct drives structure on the process of involute tooth profile forming. Materials and methods. Theoretical research has considered a methodology for constructing a mathematical model that describes the transfer of angular errors that occur during the operation of the vertical hobbing machine’s workpiece drive to the involute tooth profile. Results. The occurrence of notches on the involute tooth profile, perceived as roughness, is associated not only with the intermittent nature of the hobbing process but also with angular oscillations inevitably accompanying the operation of the vertical hobbing machine’s workpiece drive. The magnitude of the profile error resulting from angular position errors is determined by the amplitudes and frequencies of the sinusoidal components of the angular oscillations. Conclusions. A mathematical model has been developed that describes the mechanism of forming the tooth profile of a spur gear, taking into account only the influence of angular errors in the table drive, without considering other errors that inevitably occur during the gear machining process. The contribution of this error to the overall process of forming the tooth profile during machining on a machine tool requires further study.

The goal of the study is to elucidate the reasons for early fracture of the gear wheel teeth of a Cameron TA9000 turbocharger (1820 kW) after an operational load up to 1.3 × 109 cycles. The chemical composition and the microstructure of the tooth metal were studied using the methods of metallography, microhardness and optical microscopy. The microrelief of fracture surfaces of operational fractures was studied using electron scanning microscopy. Analysis of the chemical composition proved the steel grade of the tooth metal (DIN 31CrMoV9) declared by the manufacturer. Visual analysis of the fragments under study revealed numerous cracks present on the tooth contact surfaces. The origins of fatigue fracture detected on the fracture surfaces are typical of high cycle and gigacycle fatigue fracture. In the latter case, the detected fracture looks like a "fisheye" exhibiting an area of structural heterogeneity with inclusions and pores in the center. The fracture probably developed from the first tooth fragment to the fifth one, being accompanied by an increase in the number of origins of fatigue fracture known to be attributed to an increase in the stress amplitude. Metallographic study showed the presence of a subsurface hardened layer with a thickness of 120–200 μm with a defect-containing structure associated with grain-boundary precipitates (presumably, carbides (Fe, Cr)3C), which could have resulted from violation of the modes of heat treatment of the gear wheel. Formation of brittle intergranular cracks on the contact surface and their subsequent development in the entire depth of the subsurface hardened layer appeared to be the reason for a decrease in the strength and bearing capacity of the gear teeth. The interaction of the resulting cracks with longitudinal microcracks that originated from defects due to poor-quality mechanical processing of the gear led to the formation of centers of fatigue cracks, the development of which caused the final destruction of several teeth. [ABSTRACT FROM AUTHOR]

This article considers the regularities of abrasive particles activity changing in the oil of machine units, which take part in the process of gear-wheel wear at constant and increasing concentration varying with the number of loading cycles of gear teeth, considering the share of crushed abrasive particles in one loading cycle of the gearing which is used to determine the oil replacement time in the machine unit. [ABSTRACT FROM AUTHOR]

Hard finishing of gearings such as continuous generating gear grinding is highly essential for manufacturers due to increasing demands on gearboxes regarding quality and economical aspects, especially in the growing field of electric mobility. Here, high requirements on the acoustic behavior and low production cost come into conflict in the last stage of manufacturing gearings in a particular way. Against this background, in‐process evaluation methods for manufacturing processes are developed in order to reduce scrap parts and to exploit the process limits by collecting and processing of sensor signal data and by adapting measures based on reasonable process models. This investigation shows how the condition of abrasive tools and workpiece quality are evaluated by means of process near acoustic emission sensor application and motor current of the grinding spindle in order to adapt shifting and feed movement in generating gear grinding process. A calculation method based on a simulation process model is introduced to characterize relevant vibration frequency bands and the resulting acoustically effective waviness on tooth flanks, depending on workpiece and process parameters. Appropriate adaption of the grinding process for increasing productivity while maintaining workpiece quality is based on the findings of an intelligent in‐process evaluation. [ABSTRACT FROM AUTHOR]

Abstract Hard finishing of gearings such as continuous generating gear grinding is highly essential for manufacturers due to increasing demands on gearboxes regarding quality and economical aspects, especially in the growing field of electric mobility. Here, high requirements on the acoustic behavior and low production cost come into conflict in the last stage of manufacturing gearings in a particular way. Against this background, in‐process evaluation methods for manufacturing processes are developed in order to reduce scrap parts and to exploit the process limits by collecting and processing of sensor signal data and by adapting measures based on reasonable process models. This investigation shows how the condition of abrasive tools and workpiece quality are evaluated by means of process near acoustic emission sensor application and motor current of the grinding spindle in order to adapt shifting and feed movement in generating gear grinding process. A calculation method based on a simulation process model is introduced to characterize relevant vibration frequency bands and the resulting acoustically effective waviness on tooth flanks, depending on workpiece and process parameters. Appropriate adaption of the grinding process for increasing productivity while maintaining workpiece quality is based on the findings of an intelligent in‐process evaluation.

It is presented the design features and the principle of operation for Wankel’s rotary piston engine (RPD). It is given the analysis of scientific research aimed at improving the design of RPD. It is proposed the design study technique that allows in a graphical way to realize the construction of an RPD cylinder with a circular shape, the surface of which is made according to the epitrochoid. The derivation of equations is justified that allows to determine the coordinates of the position of the points of the epitrochoid depending on the eccentricity, the values of the radii of the initial generatrix of the epitrochoid, gear and fixed gear. It is given the calculation definition of the required value of the compression ratio. Using the Mathcad system as an example, it is shown the possibility of application mathematical software packages for calculations related to the study of the features of the Wankel’s RPD epitrochoid, its calculation, its research and its construction.

The paper presents the geometric synthesis and modeling of the geometry of the three gear wheels (flexible, fixed rigid and mobile rigid) of a double harmonic transmission. The geometric design of the wheels and their teeth was made by using particular relationships that resulted by imposing the specific conditions of harmonic engagement that exist between these wheels.Modeling of the 3D geometry of the wheel gears of the considered double harmonic transmission was performed in the SolidWorks CAD program, based on the geometric parameters resulting from performing the geometric synthesis.

The article investigates the linear static characteristics of a stainless steel gear wheel after thermochemical treatment (nitriding). As a result, the product hardness and wear resistance increase. The experiment has shown that the optimum temperature for the formation of a nitrided case with a hardness of 11 740–12 003 MPa for corrosion-resistant refractory steel 12Kh18N9T is 570–590°C with a nitriding time of 48 h. However, overly high hardness of the nitrided case increases the brittleness of the gear wheel; therefore, deep surface treatment may be required when grinding or polishing. It is shown that, after nitriding, the steel under study has a homogeneous structure with clearly pronounced transition layers; the average thickness of the nitrided case is 60–90 μm. The stress-strain state (SSS) of the product before and after nitriding, which determines the internal stresses and deformation of the wheel tooth, shows that the static characteristics are approximately equal. However, a nitrided wheel has a higher hardness, greater safety margin and less tendency to deform at high loads. [ABSTRACT FROM AUTHOR]

The paper provides an overview of systems and devices for lubricating mechanisms, including devices for monitoring the level of the lubricating fluid and its possible contamination, as well as systems for the effective supply of oil to the mechanism, presented in modern literature, patents, and inventor's certificates. The given devices can be used at chemical and petroleum engineering enterprises. [ABSTRACT FROM AUTHOR]

Numerical modeling of induction hardening of gear wheels made of steel AMS 6419 (AISI 300M) was presented in the paper. In order to determine correct values of critical temperatures for investigated steel Time-Temperature- Austenitization (TTA) and Continuous-Cooling-Temperature (CCT) diagrams are measured. Mathematical model of the process is formulated and described. Exemplary results are presented. Final conclusions are formulated.

Gear boxes must provide for the automobile with the best dynamic and economic qualities for the power and revolution of the internal combustion engine. In order to do this, it must have a simple design, light weight, reduced gauge, high reliability and easy maintenance. In this paper, based on the constructive solutions and the geometric elements that were calculated, we obtained a 3D modelling of the elements of the transmission of a gear box and the assembling of these elements in order to obtain the constructive dimensions of the gear box and in order to verify the other composing elements (shafts, bearings, synchronization mechanisms).

The experimental stand for investigation of induction surface hardening of gear wheels was described in the paper. In order to control parameters of the process a specialized equipment for identification of all important process parameters including registration of temperature changes in time and measurements of current intensity was installed. Exemplary results are presented. It is planned that the stand will be used as a demonstrator for a presentation of advantages of modern induction hardening technologies.

This article is dedicated to the subject of gearboxes, with a specific focus on the load distribution on the tooth. The aim of the study was to review the selected solutions and methods that can contribute to aligning the load on the width of the tooth. The structure and operation of each solution are described in detail. The paper presents the possible benefits of using the described solutions.

Additive manufacturing gives new freedom to part design by enabling the manufacturing of complex structures. Mastering this degree of freedom poses challenges for product developers with experience from conventional manufacturing. In order to meet this challenge in a structured manner, a practical method is presented in which creative idea development is combined with software-based design optimization. First, optimization goals are defined. Then a baseline design is developed through a creative ideation process. Variants are derived from the baseline design, evaluated according to simulation results and selected. The method is illustrated by the development of a lightweight and function-integrated gear wheel. [ABSTRACT FROM AUTHOR]

The paper presents the geometric synthesis and modeling of the geometry of the three gear wheels (flexible, fixed rigid and mobile rigid) of a double harmonic transmission. The geometric design of the wheels and their teeth was made by using particular relationships that resulted by imposing the specific conditions of harmonic engagement that exist between these wheels. Modeling of the 3D geometry of the wheel gears of the considered double harmonic transmission was performed in the SolidWorks CAD program, based on the geometric parameters resulting from performing the geometric synthesis. [ABSTRACT FROM AUTHOR]