Research of the Process of Production of Steel Square Continuous Billets for Rolling Balls of Large Diameter

The paper investigates the technology of production of steel billets continuously cast billets for rolling balls of large diameter. In Kazakhstan, in connection with the development of new copper deposits such as Aktogay and Bozshakol, the need for large diameter steel grinding balls for primary ore processing has increased. The main problem in the operation of large diameter grinding balls is the tendency of the grinding media to break during operation. The authors of the work investigated the process of production of steel billets continuously cast billets with a cross section of 150 × 150 mm for rolling balls of large diameter (d 125 mm) in the PB LLP "KSP Steel", which showed that the breaking of grinding balls is initiated mainly by the presence of internal discontinuities (gas axial looseness) in continuously cast billets. Studies have shown that the technological scheme for the production of grinding balls with a diameter of 125 mm from continuously cast billets with a section of 150 × 150 mm, including steel smelting in an arc furnace with steel finishing on a ladle-furnace unit, deoxidation with aluminum and degassing in a ladle vacuum apparatus, casting steel in a closed jet on a continuous casting and further production of rolled stock on a rough rolling mill ensures the absence of internal discontinuities (gas bubbles, axial looseness) in the workpieces and ensures the production of high quality balls.

Effect of off-sized balls on contact stiffness and stress and analysis of the wear prediction model of linear rolling guideways

The characteristics between the rolling balls and raceways are the key to study a linear rolling guideway (LRG). In this paper, the contact stresses of an LRG with off-sized balls incorporating the variation of the contact angle are given by the established LRG joint model. Moreover, the effect of the location, number, and the deviation degree of the off-sized balls on the stress distribution are studied. In addition, the contact stress distribution between the balls and raceway for different arrangement cases of the off-sized balls are analyzed. The random arrangement case can improve the stiffness and service life of the LRG. Based on the Archard wear theory, the wear prediction model of the LRG is established and the displacements and angular displacements of the slider caused by wear in reciprocating motion are obtained. The effectiveness of the contact stiffness and wear prediction model of the LRG is verified by simulations and analysis.

DIDACTIC MINI VIDEO GAMES – STUDENTS’ AND TEACHERS’ POINT OF VIEW

Computer games are used more and more often in education. Their application in the learning process brings a lot of benefits and advantages compared to the classic form of teaching without the use of new technologies. Some of the more sophisticated games can include a variety of smaller ones, which supplement their functionality. In this article are described in detail the mini-games, which will be part of a 3D educational labyrinth game. They include: quiz, 2D puzzle, solving a Wordsearch Puzzle, rolling balls, shooting on moving inanimate objects, etc. The characteristics of mini-games are considered, and they may be mandatory or optional. The opinions of students and teachers regarding their preferences for the mini-games and the results are studied and compared. Surprisingly, according to the survey, teachers show a more positive attitude towards educational games than students. The APOGEE project aims to create a platform for automatically generating an educational 3D labyrinth game that can be easily used by teachers, even if they are not IT specialists. Thus, they will have the opportunity to choose the right mini-games and the necessary training material.

A research on the time-varying stiffness of the ball bearing considering the time-varying number of laden balls and load distribution

In response to the fact that not all rolling balls are laden when the angular contact ball bearing working under the condition with certain combined loads especially when the axial preload is not large enough, an analytical method for the determination of the time-varying stiffness of angular contact ball bearing considering the effect of time-varying number of laden balls and load distribution is proposed in this paper. According to the definition of the stiffness, the time-varying stiffness under different sets of combined loads is obtained by the implicit function derivation method. Only the principal diagonal elements of the stiffness matrix are studied for the sake of simplicity. Several numerical examples are simulated and the simulation results indicate that the time-varying number of laden balls and load distribution have a significant effect on the stiffness. The period of the time-varying stiffness is consistent with the time required for the cage to rotate the angle between the adjacent rolling balls. The calculation of the ball bearing quasi-static model and the analytical method for the determination of the stiffness is verified by the existing references.

Topics in Mechanics

Chapter 2 provides a comprehensive review of the classical mechanics required when building vehicle models. Both vector-based methods and the variational approach to classical mechanics are reviewed, and efforts to highlight the links between the two approaches have been made. A wide range of illustrative examples with a particular focus on non-holonomic systems are studied, including Chaplygin’s sleigh, rolling balls, and rolling discs. Equilibria and stability, and the connection between timereversal symmetry and dissipation, are also briefly discussed.

Sticking of a Linear-Guideway Type Recirculating Ball Bearing

In this paper, the driving force of a linear-guideway type recirculating ball bearing (linear bearing) is measured and explained as the first step toward an understanding of sticking, which is the significant increase in driving force required to move a linear bearing under back-and-forth operation with a short stroke length. First, the driving force required for operation of a test bearing (which is a linear-guideway type recirculating ball bearing with load balls) and acceleration of a moving body (which consists of a carriage of the test bearing, an arm, and weight) were measured. The measurements showed that the sticking occurred when the test bearing, under a relatively higher rolling moment load, was driven in an offset position for a certain period. Next, the driving force of a test bearing with alternating load balls and spacer balls was measured, and it was clear that the cause of the sticking was the sliding friction between rolling balls. Finally, the ball locations in the load zone of the test bearing with load balls were observed in operation, and the occurrence process of the sticking is explained.