A. V. Korolev

Waste-free ultrasonic bearing assembly

We know that assembly is more difficult to auto� mate than machining. As a result, assembly is still a laborious operation and does not always ensure the required quality. Until recently, the assembly of ball bearings was a prime example. The previous methods for assembly of ball bearings with a singlegap external race were inefficient; the bearings produced were rejected at rates sometimes exceeding 10%. Accordingly, scientists at Saratov State Technical University and OOO NPP NIM (a producer of non� standard manufacturing components) have developed a wastefree ultrasound technology for ballbearing assembly (1, 2). This technology improves bearing quality and eliminates waste. In the present work, we investigate the assembly of ball bearings with a singlegap external race and pro� pose a corresponding mathematical model. We deter� mine the dependence of the displacement of the inter� nal race during assembly, the forces required to deform the outer race, the bending moments and internal flex� ural stress in different cross sections of the race, and the rejection probability on the geometric parameters of the races and the tool employed in assembly. The formula for the rejection probability reflects the ran� dom distribution of the flexural stress within the exter� nal race. The failure probability of the external race in assembly is

Deformation of bearing components under an axial load for mechanical stress relaxation

The load distribution among the rollers in thrust–radial bearings is determined. Their deformation under an axial force for mechanical stress relaxation is studied.

Solid lubrication of the raceways in bearings with ultrasonic stress relaxation

Experimental data on the ultrasonic treatment of thrust-bearing raceways are presented. A mathematical model of the process is proposed. Graphs show the influence of each factor.

Grinding the roller channels in thrust-bearing races

A method is proposed for ensuring precision of the roller channels in thrust-bearing races. The dependence of the track thickness at the bottom of the channel on the machining parameters is discussed.

Cutting geometry of abrasive grains

The geometry of abrasive grains and their cutting section is considered. This is a very important characteristic of the working surface of abrasive tools.

Roller bearings with rational working surfaces and their manufacture

The development of bearing production may be divided into three stages. The first dates back 500 years, to the invention of ball bearings and roller bearings by Leonardo da Vinci (1452-1519). Intent on reducing friction in machines, Leonardo had the idea of using round bodies. I see no great difference between them, except that balls may turn in all directions and rollers only in one. However, if balls and rollers are in contact as they move, their motion will be slower, on account of the opposing frictional force. In surviving sketches, we may see the separator proposed by Leonardo for the division of the rollers. True to his principle of a compre� hensive approach to engineering problems, Leonardo suggested means of reducing friction and wear in machines that have only been implemented many years later in various countries. For example, Leonardos rec� ipe for a metalalloy lubricant is similar in composition to the bearing material proposed by Babbitt in 1839. The second stage is associated with the theoretical developments of Heinrich Hertz (1857-1894), per� mitting the calculation of the contact area and the contactstress distribution over the contact area. In solving the contact problem, Hertz assumed that the initial gap between the contacting bodies is a quadratic function. This framework remained unchanged for around sixty years. In that period, Hertzs theory was experi� mentally confirmed, and possibilities for its practical application were explored. We should note, in particular, the contributions of N.M. Belyaev and A.N. Dinnik. Only sixty years ago, on the basis of work by Muskhe� lishvili, Vekua, Lyapunov, and others, I. Ya. Shtaerman developed solutions for the case of a circular contact area and an arbitrary initial gap and also for the case of an elliptical contact area with a biquadratic initial gap. However, like Hertzs solution, Shtaermans approach did not apply to the contact of asymmetric bodies. Many Russian and nonRussian solutions have attempted a general solution of the contact problem. Their work is of great theoretical and practical value, since it permits the determination of the bodies stress-strain state in different conditions. As a result, it is possible to determine the stress and strain close to the contact zone for the interaction of bodies charac� terized by nonuniform materials, nonuniform layers of material, asymmetric load, a nonuniform contact sur� face, and various profiles: a wedge, a cone, a truncated sphere, a parallelepiped, a cylinder, a torus, etc. The most general solutions may be found in (1-3) and elsewhere. In these studies, analytical expressions are given for the dimensions of the contact area and the contact stresses between roller bodies of arbitrary form. On that basis, for the first time, it is possible to pre� dictively control the contactstress distribution between the roller bodies. In the figure, we present examples of the stress distribution in the contact zone as a function

High-efficiency automated line for precise cold rolling of bearing rings

751 New metalworking methods are essential to rapid progress in Russian manufacturing. An important development in manufacturing is the replacement of cutting processes by pressure treatment of cold metals, such as cold rolling and the profiling of solids of revo� lution (knurling). The history of plastic deformation by rolling extends back over 120 years, and Russian specialists have made significant contributions to its more recent development. Compared to cutting, knurling has the following benefits: considerably reduced metal consumption; improved productivity, precision, and final surface roughness; reduced operating costs (for the cutting tool and other equipment); reduced demand for production space; and reduced costs and amortization. The preci� sion of profile elements produced by rolling matches

Waste-Free Splitting

Waste-free splitting of rings with ultrasound application is studied experimentally. Single-break fracture of ball-bearing races is investigated, using a PARK semiautomatic ultrasound system.

Waste-free manufacture of shaped rollers

A waste-free manufacturing method for shaped rollers is considered. A plain bar is used as the blank. The technology consists of three simple steps: knurling of slots onto the bar; breaking of the bar into pieces; and knurling of the outer surface of the blanks. This technology reduces the consumption of power and materials and greatly boosts manufacturing efficiency.

The cutting energy and the rate of removal of the margin in abrasive superfinishing

A relation is established between the cutting energy in superfinishing, which is a generalized characteristic of abrasive machining, and the removal of the margin, which is one of the basic characteristics of this process. This approach permits effective improvement in abrasive machining.