The scientific foundations of the technological regulation for the selection and assignment of processing parameters during gear milling are based on the fundamental theoretical provisions of the friction theory, mechanical engineering technology and cutting theory. For the first time, the sliding angle was scientifically substantiated during plastic displacement (pre-deformation) of the material, when the material flows around the indenter (tool) without separation from the main mass. Determination of the minimum sliding angles during the processing of large-module gear wheels by milling, based on the physicochemical processes of friction mechanics, can significantly increase the efficiency of the tooth shaping process and the operational properties of their surfaces. An atomic approach to the processes of deformation and destruction of chips during cutting is presented. The resistance to plastic deformation of the cut layer depends on the type of crystal lattice of the processed material, its stacking fault energy, and the presence of impurities at the grain boundaries. The influence of these factors is manifested through the types of dissipative structures that are formed in the process of deformation of the cut layer and determine its localization.
The issues of efficiency improvement in hydrodynamic (liquid) or limit (semi-liquid) modes of friction of gears with an asymmetric profile and the effect of the liquid on tooth damage, power loss and temperature in contact, as well as the role of an elastic medium that dampens shocks and changes contact lines, are considered. In many gears, the tooth load per tooth is much higher and applied for longer periods of time. The asymmetrical shape of the tooth reflects this functional difference. In the case of asymmetric gears, the standard symmetrical toothed tool rail is modified by changing the pressure angle of one of the side surfaces. However, this simplistic approach to the design of an asymmetric transmission significantly limits the ability to maximize the performance of a wide range of possible applications of these transmissions. As the frequency of impact interactions increases, the lubricating layer of high-speed gears with an asymmetric profile ceases to respond to pressure changes, and the load value, which determines the smallest layer thickness over time, approaches the minimum stationary component of the spectrum of dynamic loads. At the same time, noise and vibration levels are slightly reduced. Therefore, in the calculations of the strength, contact endurance and seizure of high-speed gears with an asymmetric profile, the complex influence of the criterion parameters of the lubricant must be taken into account not only when determining the allowable stresses, but also when determining the amount of dynamic load amplification due to the impact interaction of the teeth.
Considered in the article. expansion of technological capabilities of machine tools mod. 528С for cutting bevel gears with a circular tooth with an increased outer taper distance of the gears with a crossing angle of 300. Optimizing programs are analyzed to determine the geometric parameters with obtaining the localization of the contact zone in height, for the tooth shape III, even on a machine tool without tilting the tool, and in the presence of a machine with the inclination of the tool spindle, widely apply the double-double-sided cutting method for a wide range of bevel and hypoid gears, and not only for gears of small modules, but also for wheels of medium modules, which was previously considered impossible without the use of special machines with helical movement. The machine settings with an increased external taper distance on a machine with insufficient adjustment offsets are analytically determined. As a result, it was found that with certain axial displacements of the headstock of the product, it is possible to place a wheel blank with an increased size of the outer conical distance. In this case, the processing is carried out by a reduced flat producing wheel. Partial displacement of the lateral surface of the wheel teeth is compensated by the optimization of the setting parameters when processing a paired gear, while the calculated displacements, due to the possible intersection of the wheel with the base parts, can be corrected upwards. The new displacement values are again entered into the optimization program as initial ones.
The questions of features of application of a mill with the separate scheme of forming are considered. The characteristic of non-uniformity of loading on the tool connected with various schemes and design features of gear cutters is given. It is shown that the nature of the torque waveforms of the cutter with a separate shaping scheme indicates a greater smoothness of the cutting process and less cutting effort. Cutters with a separate shaping scheme have 1.75 times more teeth at the length of one turn of cutting than a standard cutter. In the range of investigated feeds 3-6 mm/rev, the average torque when working with a cutter with a separate shaping scheme is 2-2.5 times less than when working with a standard cutter that treats the side surfaces and bottom of tooth cavities, and 1.5 times less when the standard cutter does not process the bottom of the teeth.
The paper develops a theoretical approach to determining the cutting temperature during grinding and the conditions for its decrease, taking into account the balance of heat leaving the chips and the workpiece. It has been established that with an increase in the contact time of the wheel with the material being processed, the cutting temperature continuously increases, asymptotically approaching the maximum cutting temperature, which is determined by the ratio of the conditional cutting stress to the specific heat capacity and density of the material being processed. Based on this, it is proposed to consider the maximum cutting temperature as a new universal technological processing parameter that determines its potential and allows comparing various machining methods according to the temperature criterion and choosing the most effective of them. On this basis, the main direction of reducing the cutting temperature and improving the quality and productivity of processing is substantiated, which consists in reducing the maximum cutting temperature to the level and below the melting temperature of the material being processed. This makes it possible to carry out grinding with a significant machining capacity with virtually no increase in cutting temperature. It is shown that the main condition for reducing the maximum cutting temperature is to reduce the conditional cutting stress.
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