Vol 37, No 7 (2017)

Cylindrical magnetic clutches based on highly coercive permanent magnets whose active length is less than their width are considered. On the basis of the results, correction factors may be introduced in calculating the torques transmitted by the clutches.

The balancing of equipment may be improved by reducing the number of cycles required. That calls for a dynamic model of the part being balanced. It is established that this model must be based on vector coefficients characterizing the influence of imbalances in the correction planes of the part on the vibrations of its bearing in the balancing machine. Formulas for these coefficients are obtained, as well as an algorithm for their computer calculation. By simulation, the changes in the vector influence coefficients are determined as a function of the balancing variables.

For a gun drill, automatic calculation of the shaft’s parameters and flexure is proposed to prevent its contact with the surface of the hole being machined and so increase the tool life. A refined model of the forces and torque on the drill is employed.

Equations are derived for assessing the machining forces and damage in workpieces. The mechanical anisotropy of the initial material and the workpiece dimensions affect the stress–strain state, the flow kinematics, and the limits of pneumatic shaping with short-term creep, as here established. The mathematical models obtained and the corresponding theoretical results may be used in developing rotary-drawing technology.

The contact of elastic bodies with viscoelastic coatings is considered, in the presence of lubrication. The one-dimensional Kelvin model is employed for the viscoelastic coatings. The pressure distribution in the lubricant layer and the layer thickness are investigated on transition from low to large loads.

The automated design of special machine-tool attachments for the machining of high-tech parts and assemblies in order-based production is considered theoretically and experimentally. New models and methods are discussed.

The design of optimal automatic machining cycles for numerically controlled metal-cutting machines is considered, in theoretical terms. Dynamic programming permits the optimization of an unlimited number of control parameters for all the machining operations in numerically controlled metal-cutting machines.

The stress state of interchangeable hard-alloy cutting heads of modular drills is studied. The influence of the structural parameters of the heads on the cutting stress and strain is established. Cutting heads of increased strength and modular drills with improved performance are described.

The properties of an elastic abrasive tool are considered: specifically, its rigidity, elastic modulus, Poisson’s ratio, and cutting microrelief. On that basis, the interaction of the tool with the machined surface is analyzed, and the material removed and the final surface roughness are determined.

Determination of the cutting force in end milling on the basis of the Johnson–Cook phenomenological model is described. The numerical results obtained by this method are compared with experimental data.

A method is proposed for regulating the unit that automatically maintains the arc voltage in the plasma cutting of metallic sheet. The method is based on optimal control of a mechanical system modeled by means of a second-order differential equation. This permits faster correction of the control error and hence increases the cutting speed.