No 6 (2024)
Technologies of mechanical processing of workpieces
TRANSFORMATION OF NARRATIVES OF THE CUTTING OPERATION THEORY IN PASSING TO THE «DIGIT»
Abstract
The main tasks of the theory of metal cutting in the traditional scientific view of the mechanisms and patterns of tool wear in the operation of edge cutting machining are viewed. It is shown that the need for continuous expansion of the field of interests of specialists is derived from the improvement of construction and tool materials as well as blade tools structure. It is caused by the expanding spread of hard-alloy tools having multilayer wear-resistant coatings, structural materials with increased physical, mechanical and special operation characteristics. Exclusive standards for the stability of machining operations resulted from the gain in specific weight of expensive CNC equipment in the total mass of production tooling for machining industries. The customization of machine-building production and functional requirement toughening for the manufactured products specifies reliability growth for the results of machining. The factor determining the «vector of attention» change regarding metal cutting science should take into account the expansion of information technologies influence and, in particular, the development of artificial intelligence systems. It is shown that the existing means of digitalization can significantly increase the efficiency of machining production due to the developed means of mathematical modeling and forecasting of processing results. An additional mechanism for ensuring the stability and reliability of metalworking should be considered as the transition from monitoring systems of the technological system element state to adaptive control systems with a feedback. The possibility of adapting cutting conditions to the «instantaneous» state of the elements of the technological system is proved, taking into account the stochastic nature and a variability of the properties of the contact pair «tool – material blank». Thus, digitalization and intellectualization of production determine the transformation of views on the subject as well as metal cutting techniques.
Science intensive technologies in mechanical engineering. 2024;(6):3-12
3-12
Technology and equipment of metal processing by pressure
PRESSING HI-TECHS IN MECHANICAL ENGINEERING, AVIATION AND TRANSPORT
Abstract
Abstract. Results of workpiece thickness variations due to sheet metal stamping job, that is: tube bending, pressing, stretching, drawing-out, ironing are presented in the paper. The necessity in such work is fuelled by the contemporary increasing requirements for parts strength resulted from sheet metal stamping. Much attention is paid to tube bending, for it is bending that changes not only form of the section of the tube billet, but also leads to a thickness loss in a tensile layer together with an increase in thickness of a compression zone. The methods of reducing tube thickness variation are proposed. Results of changes in workpiece thickness under drawing-out are given. It is shown that increasing the punch radius can reduce the thickness variation by 10 %. In most studies on sheet stamping, the thickness of the primary blank and rolled iron is not taken into account, while the primary part thickness can vary by 20 % when ordering metal of single precision. A thick-sheeted drawing-out in the AutoForm program is simulated in order to determine the possibility of the program in predicting changes in the shape of the sheet and thickness due to the action of bending. It is shown that AutoForm models the shape of the part well enough after stamping. According to the specification, AutoForm and the experiment showed similar results in thickness and also revealed areas with minimal thickness. For the selected stamping parameters, the minimum thickness is observed at the point of transition of the cylindrical surface to the punch radius and at the point of transition of the punch radius to the bottom plate. Since most metals subjected to sheet stamping have anisotropy properties, it has been shown by experiments and has its theoretical proof that thickness can vary significantly along the perimeter. It has been proven that the thickness variation along the perimeter of the part may exceed 35 %
Science intensive technologies in mechanical engineering. 2024;(6):13-20
13-20
HOT FORMING OF BOX-SHAPED MATERIAL BLANKS UNDER ISOTHERMAL CONDITIONS
Abstract
Core operations with hollow products, having a periodically changing internal profile, consists in the final machining of press forgings. However, at the same time, metal rejects are high, and despite the high quality of the products obtained, their mechanical characteristics do not always meet the requirements of functioning. For the equipment units, when subjected to heavy loads, the parts are usually made of high-strength materials. Due to the complexity of the work on a workpieces made of high-strength alloys, operations are carried out with heating of the deformed zone of the in-process part or with a total heating. The use of slow deformation in the hot state under certain speed conditions is promising. The process of the internal pattern formation for hollow shells made of titanium alloy VT6 is viewed. These products are mainly used as various airframes and are made using special methods of mechanical engineering. Due to the use of high-strength billet materials, there are difficulties with the mechanization of the production methods. The article evaluates force conditions for generation of geometry on the shells based on CAE modeling. The simulation was performed in the deform complex. The focus of the research was on the assessment of deformation forces and stress intensities. The influence of deformation ratio, strain rates, punch geometry on the strength of the process and stress intensity has been revealed. A regression equation to estimate the forces of the process is deduced. Recommendations on the design of fillets forming operations have been obtained. Deformation modes aimed at achieving rational power modes, respectively, loads on the tool, which indirectly affects its durability, as well as the stress condition in the product, have been found.
Science intensive technologies in mechanical engineering. 2024;(6):21-28
21-28
Technologies of electromachining and combined processing
TECHNOLOGY OPTIONS FOR ROTATING MAGNETIC FIELD WHEN USED IN METALWORKING INDUSTRY
Abstract
Research results and ways of applications of the electromagnetic forces method in metalworking production for the operations of parts hardening, dry-lubricant coating processes, slurry waste upgrading in grinding production, are presented. The essence and means of method techniques are revealed. Analytical dependencies, recommended modes and conditions for performing magnetodynamic treatment under technological operations are given. It is found that the main energy deposition impact factor as a target exposure for the object under treatment or waste management is a magnetically vibrating layer formed in devices that create a rotating electromagnetic field and provide an operational benefit due to the occurrence of various physical effects and the intense movement of particles of a dispersed medium. Design and technological solutions of technological systems have been developed using devices with a rotating electromagnetic field, allowing for high technical and economic efficiency to provide: hardening of slender parts having long length, as well as parts with hard-to-reach internal cavities; slurry waste management in grinding production in an attempt to obtain processed raw materials for powder metallurgy, tool and foundry production. It is shown that electromagnetic forces method is quite effective for applying dry-lubricant anti-friction coatings on the surface of parts, making it possible to form traces of shock-pulse action of indentors on the surface of the treated spherical and elliptical shape , which prove the formation of a lubricant film; allowing height reduction of the irregularities and increasing the radius of apex of salient roundness together with the true contact area between the coating and the metal surface ; ensuring the adhesion of the coating over the entire contact area of the indenter with the metal surface; providing the uniformity of the application of a lubricating film on the surfaces of parts having various complex shapes.
Science intensive technologies in mechanical engineering. 2024;(6):29-35
29-35
Science intensive technologies in machine assembly
ADAPTABLE SYSTEM OF EQUIPMENT AND JIGGING FOR AUTOMATIC ASSEMBLY
Abstract
Currently, industrial robots are widely used to perform position checking tasks through minimum contact, that is spot welding, spray painting, packaging and loading and unloading operations. However, performing assembly tasks with high tolerances is still a big problem for robots due to various uncertainties about assembled parts, i.e. clamp holdings, slave tools. To correct these errors, it is necessary to have positive mobility, which is called adaptation of part position. Mobility adaptation can be achieved through active or passive means, as well as a combination of them. Passive adaptation methods are based on the use of elastic and damping elements. The structures are designed in such a way that the forces arising at the points of contact of the parts correct the errors of their position. Active adaptation methods are based on adaptive feedback control, when the assembly process and the position of the parts are adjusted automatically by measuring the position and due to contact forces. From this perspective, the expanding of research and development has led to the high robotic technologies for industrial applications. Modern technologies of robotic assembly are analyzed for better understanding of technological trends in the development of industrial robots, constraint recognition of production methods and specifying the lines of future research in this area. In this article, the typical "shaft- spacer" operations are of particular interest. Assembly control strategies are classified based on the assembly pattern. Robotic assembly management strategies and existing technologies boundary conditions are discussed in detail specifying the lines of future research in adaptable control of robotic assembly.
Science intensive technologies in mechanical engineering. 2024;(6):36-48
36-48