Journal of Machinery Manufacture and Reliability最新文献

To design effective machines and devices, it is proposed to use disposable combined reflectors that are destroyed after accumulation and flow of thte explosion products of charges of solid explosives. This new technical solution required improvement of experimental methods, including for a more complete assessment of the transformation of the directed flow of explosion products onto lead targets.

Technological approaches to improving the durability of the power steering system of a truck are considered. A technology for high-service-life repair of the hydraulic pump of the power steering system is developed. According to the operational testing results of new and repaired hydraulic pumps of the power steering system of a KAMAZ vehicle, it has been found that the average overhaul life of the units is 1.16 times higher than the prerepair service life.

The results of a study on the use of wave technology for the preparation of hydrocarbon-based drilling fluids are presented. It is shown that the use of vortex-type wave generators can significantly improve the quality of the emulsion, reduce the preparation time, and reduce the proportion of the hydrocarbon phase without deteriorating the key parameters of the solution. The experiments carried out confirmed the effectiveness of the wave action in comparison with traditional mixing methods.

The influence of the misalignment angle during gear engagement on the service life of a transmission, expressed by the number of loading cycles to failure of the gear wheel teeth, is investigated. An approach is proposed that makes it possible to solve the problem analytically and obtain a relationship between the misalignment angle and the number of cycles to failure. Such a relationship is derived based on the well-known empirical correlation between the level of contact stresses and the fatigue life under cyclic loading. The analytical dependences obtained can be used at the stages of design and engineering development of gear transmissions, especially in choosing the optimal engagement parameters and predicting the resource of gear systems under conditions close to real operation.

A launching device having a constant traction force based on elastic hinges with an assigned characteristic is considered. The elastic hinge in this case represents a pneumatic spring moving between the guides of a calculated shape. The restoring moment of the elastic hinge is set such that the traction force of the launching device is constant almost throughout the entire working area. In the case of such a characteristic, the accumulated energy at the same maximum tension force is significantly greater than that inherent in the existing catapults and crossbows. It is proposed to use such a launching device as a catapult for unmanned aerial vehicles (drones) and crossbows.

The problem of a transverse displacement plane with two pairs of two-periodic (corresponding to the X and Y axes) cohesive cracks of unequal size, weakened by two-periodic round holes, is considered. The circular holes are filled with reinforcing fibers. Boundary problems between the filler and the matrix and along cohesive cracks are defined. The solution to the problem is sought in the form of an analytical function of a complex variable. A system of unequal algebraic equations is found along the holes, and singular integral equations are constructed along the cohesive cracks, which are reduced to a finite linear algebraic system of equations using mathematical transformations. Both systems are solved jointly by the Gaussian method, and crack growth is determined by the formulas for the stress intensity factor at the crack tips. The stress intensity factors are found by changing the crack length depending on the radius of the round holes. A 3D model has been constructed.

A mathematical model of a flexible rotor interacting with a limited-power motor is considered. The rotor is modeled by an Euler–Bernoulli beam with a uniformly distributed mass and a rigid unbalanced disk. The limited-power motor is characterized by a static characteristic. The equations describing joint transverse oscillations of the rotor and its rotation are presented. The solution of the problem is presented in the form of a Fredholm integral using the Green function with subsequent discretization by trapezoid method. The results obtained demonstrate the existence of the Sommerfeld effect in the first resonance region. The influence of the motor power on the rotor “sticking” upon passing the critical speed is analyzed.

The problems of organizing the movement of a stepper drive of a three-coordinate manipulator in the remote control mode using incremental encoders integrated into the motion controller mechanism with a kinematic structure similar to that used in the actuator are examined. Control laws with different approaches to organizing the movement are considered. A single simple control law is given, the same for each of the coordinates, allowing for organizing a three-coordinate remote control without using feedback. The advantages and disadvantages of this control method are considered. Program codes for use with Arduino Uno processors are given.

The issues related to the application of a hard alloy in thrust bearings of pump sections of high-speed vane pumps, based on experimental studies conducted on a modernized test rig with a multiplier, are addressed. The tests showed that within the rotational speed range of 60–7300 rpm and a load of 1000–9000 N, a hydrodynamic lubrication regime is realized. When the bearing is stopped under load at low rotational speeds, surface damage occurs in the form of radial cracks and circumferential scratches on the inner side. The influence of high rotational speed results in the formation of vortices and hydraulic resistance in the entrance area of the oil discharge grooves, leading to oil starvation. For the use of a hard alloy bearing as part of the pump section of a high-speed vane pump containing abrasive particles in the formation fluid, it is necessary to assess experimentally the permissible magnitude of the axial force that prevents catastrophic destruction of the friction surface.

This article is devoted to the history of the development of the science of parallel structure mechanisms in Russia and abroad from the 19th century to the 1980s. The key stages in the development of this direction are considered, starting with the study of closed kinematic chains and ending with the first industrial application of parallel robots. Particular attention is paid to the contribution of domestic scientists such as P.L. Chebyshev, L.V. Assur, and N.I. Mertsalov, as well as foreign researchers, including E. Gough and D. Stewart. Important patents and inventions that laid the foundation for the further development of parallel robotics are described. This article provides an overview of the most important scientific and engineering achievements in the field of parallel mechanisms up to the 1980s.