Vol 38, No 9 (2018)

The influence of vibration on the operation of cardan joints is studied. An equation is derived to describe the oscillation of the needle’s skew angle in bearings under the action of the variable torque from vibrational forces. In both dynamics and statics, this angle is found to depend on the dimensions of the joint and on the load applied to a single needle in the operational zone of the bearing.

More reliable protection of large high-speed systems from spontaneous speed increases is considered. To that end, a smart mechatronic module with a system for determining the surface quality of the structural components may be introduced in the automatic safety mechanism. That excludes operator participation in verifying safety-system performance.

The concept of manufacturability is refined. The method of assessing the manufacturability of product designs is analyzed. The basic properties of designs and their relationship to the product’s characteristics are studied. Approaches to determining the manufacturability of designs are presented.

Structural, subeutectoidal structural, and tool steels are studied. Their boriding is considered. Equipment for electrolytic boriding and a modernized high-temperature casting crucible are presented. The conditions of electrolytic boriding are established. Shortcomings of electrolytic boriding are noted.

Vorontsov’s plastic-flow method permits the derivation of a model of cutting for the region where the tool enters the blank. The stress–strain state of the blank is determined, and the dimensions of the plasticdeformation zone are calculated. The main cutting parameters are shown to be variable.

A method is proposed for determining the state of rotary mechanisms on the basis of current signals from their electrical motors, by means of entropic indices. The results indicate that the entropic indices may be used in diagnostics.

A design algorithm is proposed for switched-reluctance motors used in manufacturing systems. The algorithm includes an optimization procedure and is based on the Monte Carlo method. In optimization of the magnetic system, it is advisable to take account of the motor’s operating conditions. The results of optimization are compared. Recommendations are made regarding the selection of the tooth-zone dimensions.

The use of an industrial robot for undulatory diamond smoothing of machine-part surfaces is considered. The design of a robot for diamond smoothing of cylindrical and complex surfaces is described, and an example of an automatic machining line that includes a two-column industrial robot for undulatory smoothing is presented. In tests, the wear resistance of samples subjected to diamond smoothing on a lathe and to undulatory smoothing is compared.

This study addresses the influence of cutting forces and mill deformation on the surface quality obtained in machining. A mathematical model is proposed for calculating the trajectory of mill deformation in the shaped surface. Tests confirm the adequacy of the model.

The accuracy of the preliminary turning of a pipe workpiece before rotary plastic deformation is investigated. The correlation of the basic hole diameters measured before and after plastic deformation is established. The influence of the machining parameters on the accuracy of the product is evaluated. For all the parameters, the accuracy is found to be sufficient.

The influence of spindle wobble in a lathe on the geometry of the machined surface is not direct. The intermediate stages involve conversion of the wobble to forces and elastic deformations. Together with the elastic deformation, wobble modifies the shaping trajectories, which are mainly responsible for the geometry of the final product. Wobble induces periodic variation in the parameters of the dynamic system. It leads not only to parametric self-excitation but also, in a nonlinear dynamic system, to the formation of various attractive deformational-displacement sets. The present work is devoted to mathematical modeling of the influence of wobble on the workpiece geometry. Cases in which various types of attractive sets are formed in the system (such as limit cycles, invariant tori, and chaotic attractors) are considered.

The physical processes associated with deep welding are analyzed. A two-dimensional numerical model is proposed for the interaction of the laser beam with the medium in the vapor channel. The following processes are considered: heat and mass transfer; absorption and reradiation of the beam’s energy by the plasma; interaction of the plasma with the channel walls; and heat transfer to the cold sample. The model establishes a quantitative relation between the welding conditions and the results of butt welding. That decreases the expenditures in the development of laser-welding processes.

The application of aluminum coatings to steel surfaces in vibrational finishing is experimentally studied. Such mechanical coatings are applied at elevated temperatures (120–300°С) by means of aluminum powder.

Low-temperature ion-plasma treatment of metal workpieces may be monitored in terms of the electrical signals recorded in the circuit consisting of the plasma, the workpiece, the clamp, and ground. The electrical signals are analyzed by means of the Hurst statistic H, which provides a basic quantitative picture of the formation and modification of the signal structure in the course of machining. Experiments show that the best results (a surface layer of maximum hardness) are obtained when machining is accompanied by the generation of signals for which the Hurst statistic indicates antipersistent behavior.