Development of Abrasive Grain Coating Technology Protective Polymer Casing for Water-Abrasive Cutting

The article presents the technology of covering abrasive grains with a protective polymer shell, which allows to reduce the wear of the focusing tube of the nozzle of a hydroabrasive installation. A description of the manufacturing process of a prototype abrasive with a polymer coating in a fluidized bed is presented in order to determine the critical processing modes at which a high-quality product will be obtained in a minimum operating time of the installation.

Modelling and Multi-objective Optimization of Elastic Abrasive Cutting of C45 and 42Cr4 Steels

Elastic abrasive cutting is a new high-performance method to produce workpieces made of materials of different hardness, which ensures lower wear of cut-off wheels and higher quality machined surfaces. However, the literature referring to elastic abrasive cutting is scarce; additional studies are thus needed. This paper proposes a new approach for modelling and optimizing the elastic abrasive cutting process, reflecting the specifics of its particular implementation. A generalized utility function has been chosen as an optimization parameter. It appears as a complex indicator characterizing the response variables of the elastic abrasive cutting process. The proposed approach has been applied to determine the optimum conditions of elastic abrasive cutting of С45 and 42Cr4 steels. To solve the optimization problem, a model of the generalized utility function reflecting the complex influence of the elastic abrasive cutting conditions has been developed. It is based on the findings of the complex study and modelling of the response variables of the elastic abrasive cutting process (cut-off wheel wear, time per cut, cut piece temperature, cut off wheel temperature and workpiece temperature) depending on the conditions of its implementation (compression force F exerted by the cut-off wheel on the workpiece, workpiece rotational frequency nw, cut off wheel diameter ds). By applying a genetic algorithm, the optimal conditions of elastic abrasive cutting of С45 and 42Cr4 steels: ds = 120 mm; F = 1 daN; nw = 63.7 min–1 and nw = 49.9 min–1, respectively for С45 and 42Cr4 steels, have been determined. They provide the best match between the response variables of the elastic abrasive cutting process.

Theoretical studies of the “Workpiece-tool” system vibroacoustic dynamics of the turning group woodworking machines

In the woodworking industry, the issue of noise reduction is one of the fundamental ones. In most cases, it is an indicator of equipment and products quality, in addition, it negatively affects the performance and irritates the nervous system of machine operators. [1]. The cause of noise is the process of cutting tool interaction with wood and it also depends on the type of wood cutting tool. For wood manufacturing, the blade and abrasive cutting tools are used. The blade instrument has a specified number of fixed shape blades and is divided into disk, cylindrical, conical and plate-shaped ones according to the shape of the body. The abrasive cutting tool on the working surface contains an indefinite number of abrasive material particles. [2]. The edge of the cutter interacts with the surface under work, along the entire width, the cutting direction is perpendicular to the cutting edge. With a small cutting depth, this does not cause significant sound vibrations, but with intensive technological modes of the treated surface, this factor is of great importance in generating noise.There are a lot of works devoted to the study of different cutting tool dependence and noise characteristics [3-7]. For example, in [8] it was experimentally proved that the noise level increases by 1-5 dBA with an increase in the number of knives from 2 to 4. This article presents the results of the acoustic system theoretical studies “manufactured workpiece cutting tools” for cantilever fixing of the workpiece of turning group woodworking machines.

Technological fundamentals of polymer-composite parts with flexible abrasive tool

There are presented investigation results of polymer-composite parts abrasion. The dependences for the definition of surface roughness at polymer-composite material hydro-abrasive cutting are shown. The results of theoretical and experimental investigations of hydro-abrasive cutting processes are presented. A procedure for their carrying out, tool and equipment used is described. The results of experimental investigations on polymer-composite parts preparation to splicing are shown. A procedure for designing a technological process of polymer-composite parts abrasion is offered.

Technologies for processing materials based on glass-fiber materials

The review of basic methods for glass-fiber material machining is shown, characteristic features are presented also advantages and drawbacks of different processing methods are mentioned. There is shown a description of glass-fiber material edge machining. The alternative methods such as hydro-abrasive cutting and laser working are considered.

DEVELOPMENT OF THE SOCKET MODULE OF THE ELECTRICAL NETWORK

Purpose of the work is to determine the method of emergency de-energization of the object by cutting stranded live wires without the manifestation of emergency modes of electrical networks. Methods. As research methods, a comprehensive approach is used, which includes the analysis of research on emergency de-energization, laboratory research to determine a safe way to cut stranded wires under voltage. Results. De-energizing various objects during rescue operations and firefighting is one of the important tasks that must be performed in order to create safe working conditions for rescuers themselves. It is established that one of the ways by which it is possible to cut live multicore wires without short circuits is the use of abrasive cutting discs made of rotating electrocorundum. The design of a device for trouble-free cutting of live wires, which has a rod, a cutting element, a transmission mechanism and a device for fixing the wire. In the middle of the rod is a transmission mechanism, which is used as a shaft, one end of which is connected to the motor, and the other end through a gearbox, which is fixed to the device for fixing the wire, with a cutting element. In the laboratory conducted experimental studies that showed that the cutting of wires occurs without the manifestation of dangerous factors of electric current – short circuits, sparks, electric arcs. Scientific novelty. Approaches to cutting live multicore wires with corundum disks are substantiated, which excludes the occurrence of emergency modes of electrical networks, in particular short circuits. Practical significance. The obtained results can be used to create tools for safe emergency de-energization, which creates the preconditions for improving the safety of this type of work.

Abrasive Disc Performance in Dry-Cutting of Medium-Carbon Steel

Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slabs, or tubes. Thus, the abrasive cutting-off process is applied when requiring precision cutting and productivity at a moderate price. Cut-off tools are discs composed of small abrasive particles embedded in a bonding material, called the binder. This work aims to compare the cutting performance of discs with different composition, in dry cutting of steel bars. To do that, disc wear was measured and disc final topography was digitalized in order to determine both disc surface wear patterns and if the abrasive particles bonding into the binder matrix was affected. In addition, X-Ray inspection gave information about the abrasive grit-binder bonding. Therefore, the method here presented allows identifying discs with a superior abrasive-cutting capability, by combining profilometry and tomography to define micrometrical aspects, grit size, and binder matrix structure. Results led to the conclusion that discs with high grit size and protrusion, high grit retention by bond material, and closer mesh of fiberglass matrix binder were the optimal solution.