Vol 38, No 2 (2018)

The numerical dynamic model of a ball-bearing with angular contact and oil lubricant, which allows to study movement of the bearing parts, having six degrees of freedom, is developed. The general parameters, characterizing loading of bearing retainer, are analyzed. The influence of general structural parameters of several ball-bearings on in-service operation conditions of their retainers is analyzed.

Improving the maneuverability of ships by increasing the tractional force of the thrusters is considered. To minimize the losses associated with swirling liquid flow and the variable attack angles in reversing, the traditional configuration must be modified, and the inclination of the thruster blades must be optimized. To increase the efficiency, the rotors should have different speeds and blade inclinations.

An automated monitoring system has been designed to maintain stable operation of self-synchronizing vibrational drives. By means of the system, information is collected and automatically processed. A built-in electrical feedback loop ensures synchronous drive operation.

In assessing the quality of metal-cutting machines, quantitative estimates of its various properties are required: the quality assessment is a kind of aggregate. A shortcoming of such assessment is the lack of a measure of thermal stability. Determining the thermal stability of the machine tool from the thermal properties of a sample of the material employed does not provide reliable information. Therefore, in the present work, an appropriate unit of measurement is developed by analysis of the machine tool’s motion under thermal forces. On that basis, the thermal rigidity of the structure may be determined.

The relation of the composition of wear-resistant coatings with its structure and mechanical properties and with the cutting parameters is established. On that basis, multilayer coatings are proposed and their effectiveness is analyzed.

The development of specialized information-security measures in automatic production control systems is considered. The problem is formulated; the mathematical operations are presented; and the operational algorithms of such components are described.

The integrated CAM application for the KOMPAS-3D environment known as CNC Module for Turning is considered. This application permits automated development of control programs for numerically controlled lathes. The user may readily adapt the CAM application for specific production conditions and machine tools, thanks to features such as the following: representation of the cutting tools by means of parametric 3D models, the possibility of including fixed CNC cycles in the control programs, and the use of the Python language for programming of the postprocessors.

A multimass chain model of chip formation in the secondary deformation zone is proposed. The influence of the frictional conditions and cutting conditions on the group motion of the chip elements over the cutter’s front surface is shown. The dynamics of the motion of the chip’s free end has a significant influence on its fracture. In particular, the mass ratio of the last elements involved in the group motion (and positioned on the contact line at the cutter’s front surface) and the free end of the chip gives rise to considerable dynamic splitting forces between the elements. The proposed approach offers broad scope for analysis of the conditions of chip formation, including conditions with intensification of the cutting process by electrical pulses.

Flake formation (cracking) is observed in inserts of untreated cutting ceramic and also during diffusional strengthening of the inserts’ surface layer by nitrogen on heating in a muffle furnace to 450–500°C, with the creation of γ-phase (a protective layer), the removal of carbon from the atomic cells, and the formation of titanium nitride. Heat-treatment conditions for inserts of cutting ceramic are established such that the flake content at their surface is reduced. Treatment to prevent flake formation is proposed: heating in a sealed muffle furnace with a nitrogen atmosphere to 250–280°C at a pressure of 0.25 MPa. In this process, the titanium carbide at the surface of the inserts is converted to titanium nitride as a result of carbon diffusion, with the formation of a protective γ-phase layer. By removing carbon from the surface layer of the inserts and ensuring the diffusion of nitrogen into the cutting ceramic, with the formation of titanium nitride in the γphase, the durability and performance of the inserts are improved, along with their mechanical properties.