No 1 (2017)
- Year: 2017
- Articles: 6
- URL: https://bakhtiniada.ru/1994-6309/issue/view/19970
- Description:
Full Issue
TECHNOLOGY
Method for vibration drilling holes in composite materials tool modification of cubic boron nitride
Abstract
High performance of highly engineered product processing is reached by development and adoption of special technologies based on the application of modern instrumental support and progressive tooling. The paper shows the composite materials relevance in modern engineering and also considers the problems associated with holes drilling in these materials. It proposes the ways of the increase of process efficiency and quality improvement of the finished surface when drilling the composite materials by using of the modern tool materials coupled with the instrument axial vibration. The article defines the description of the holes’ vibrational cut in higher-melting-point materials using especial device and drill equipped with cutting elements made of cubic boron nitride. The advantages of the processing method and cutting tool with composite plates over traditional tools using in the enterprises are shown. The using the cubic boron nitride plates as a cutting part of drills allows to increase the processing performance more than 7 times due to intensification of cutting modes. The created design of device for drilling machines, allows to apply axial vibration on a drill in the range 20-500 Hz. The specifications of created device support the implementation of a wide range of tool feed required spindle speed, cutting speed and required amplitude high-frequency axial tool vibrations. The circuit of two stacked inductors is accepted for converting electrical into mechanical vibrations. A direct current is supplied to fixed top inductor, and alternating current is supplied low inductor, fixed coaxially with the upper inductor, and having axial movement. The using of this device allows providing the quality of finished surface and increasing durability of cutting tool with composite plates due to adhesive wear decrease.
Obrabotka Metallov / Metal Working and Material Science. 2017;(1):6-12
6-12
Performance property of transport parts after epilamization
Abstract
The paper studied the influence of films formed by epilamization on the performance properties of the fuel pump parts. Durability and contact stiffness of the surfaces after grinding and grinding+ epilamization in the 6SFK-180-05 lubricant composition are compared. Wear of the steel 45 samples in the raw and heat-treated state are performed on the 2070 SMF-1 friction test machine using a “drive-block” scheme. The results indicate that the surface after combined treatment (grinding+ epilamization) has a higher wear resistance compared with ground, both during running-in stage and at steady-state wear. Tests on contact stiffness of the ICE fuel pump parts (stop drive and control plates) performed in a special unit, simulating the operation of the regulator, shown that epilamization reduces the width and depth of the crushing grooves in comparison with the same parameters measured on the grinding surface. These parameters reduction is indicative of the contact surfaces with the epilam film coating stiffness increase. To find out the cause of the epilamization effect on the studied performance properties, further microgeometric and physical and mechanical characteristics of the surface layer, in particular, the surface roughness (Ra) and microhardness (Hμ) before and after epilamization and oil-retaining properties of these surfaces are investigated. Epilamization does not alter microhardness and roughness but increases oil-retention of the surface. In view of the immutability of microgeometric and physical and mechanical properties of the surface after epilamation, the increase in the wear resistance and the contact stiffness due to improved oil-retaining properties of the film coating surface are assumed.
Obrabotka Metallov / Metal Working and Material Science. 2017;(1):13-19
13-19
Efficiency upgrading of composite material product production preparation
Abstract
The paper presents the ways to improve the utilization efficiency of the composites, which are proposed to replace conventional construction materials in engineering, where is possible. Software for composite material product production preparation stages of development, which include: the development of methods of forming composites database, multi-criteria analysis methods and rational choice of the composite material varied according to the compatibility of the parameters are revealed. The collecting and analysis of algorithms, the choice of the composite tool is presented. The formation of the base composition of composite materials is suggested. A software module for creation of the given composites database, the principle of software module work is presented. The software module introduces data on the form, and the designation of the brand of composite materials, its physical and mechanical properties, manufacturer, cost and image. The need in composite data structuring and organizing, analysis and synthesized decision solution of the rational composite material choice is noted. The algorithm which is based on the method of multi-criteria analysis and rational object selection is depicted. A program product for the rational choice of materials by its composition parameters (density, tensile strength: tensile, compressive, bending modulus, cost, thermal conductivity, etc.) under conditions of actual production with selection composites priority indicators and composites search by limiting the maximum number of values of the properties of composites is presented. The findings of research that reflect the spirit and scope of the performed work are described. The prospects for further implementation of the research results are reflected.
Obrabotka Metallov / Metal Working and Material Science. 2017;(1):20-29
20-29
EQUIPMENT. INSTRUMENTS
Defects in diamonds as the basis adhesion grinding
Abstract
The presented comprehensive study in the field of electrochemical grinding makes it possible to establish the rational regime of the combined electro-diamond grinding and to prove, on the atomic-molecular level, the possibility of effective grinding of high speed steels by metal-bonded diamond wheels. It is shown that the diffusive and adhesive phenomena in the contact zone depend essentially on the electrical regime of the combined electro-diamond grinding. The structural changes in the diamond-bearing layer are due to the phenomena associated with the high pressure and Van der Waals attracting forces occurring on the molecular level with high rates. Undesirable formation of the loaded layer on the diamond grinding wheel surface is a consequence of the phenomena. Disclosure of the nature formation of a loaded layer is possible only with an integrated research in the field of materials science, technology of machine building, chemistry and solid-state physics, through atomic visualization of juvenile surfaces. For that end, you must consider specifics of synthesis of synthetic diamonds, which was not considered by previous researchers. However, it is important to know which diamond crystals, with some internal and surface defects are for the manufacture of modern grinding tools. Defects arising in diamond crystals during their synthesis, give rise to the formation of more complex defects that arise in the operational process of diamonds themselves. In the analysis obtained through scanning electron microscopy images shows that even on the surface not involved in the process of cutting the diamond grains and on their edges, there are characteristic traces disorders of the crystal structure, both micro and macro levels. When external action these defects and have immediate strong effect on production characteristics of devices, products or instruments containing diamonds. This is particularly manifested in the grinding of tough, ductile materials based on aluminum, magnesium or titanium. Developed on the basis of modern digital technology and molecular dynamics visualization method allows to show it at the atomic level.
Obrabotka Metallov / Metal Working and Material Science. 2017;(1):30-39
30-39
MATERIAL SCIENCE
Laser surface melting of the cast iron SCH20 after chill casting
Abstract
The influence of parameters of laser melting of gray cast iron SCh20 on the surface topography, microstructure and microhardness is investigated. Parts of centrifugal electric submersible pumps (ESP) for oil production are made of gray cast iron. According to the chemical composition, the analyzed material is gray cast iron. But due to the rapid cooling during casting the material in its initial state has the structure of white cast iron. The rapidly cooled from the melt cast iron (chilled iron) has a high hardness and wear resistance due to the presence of ledeburite in the structure. However, it is of interest to further increase the surface hardness by laser melting. Usually white iron is slightly hardened by laser melting. However, in this case the cast iron observed significant hardening. Samples were cut from the part obtained by casting in a metal mold, and had the form of 3 mm thick plates. Laser surface melting was carried out using a fiber laser with the 1.07 mm radiation wavelength and a circular cross-section laser beam. The varied parameters were: a speed of beam movement v, a spot size d, and a power of the laser beam P. Microhardness was measured with a load of 50 grams. Laser melting in this case does not change the type of structure. However, the dispersion of the microstructure increases significantly. As a result of structure refinement, the microhardness increased from 500 to 770…850 HV0,05. When a spot size of 0.2…0.5 mm periodic relief is formed on the surface. The relatively smooth surface of the track is formed by laser beam with spot size of 2…4 mm. Simultaneously, in this case, the material has a maximum microhardness. Before and after laser treatment, the samples were weighed. Mass change Dm per unit of length of the laser tracks is determined. It is shown that the value of Dm well approximated by a quadratic dependence on the value of P/(d*v)0.4. It is known that the value of P / (d * v) 0.4 is proportional to the size of the laser melting zone. Previously, during a study of laser melting of austenitic Ni-Resist cast iron with flake graphite, it was found, that Dm is in linear dependence on the value of P/(d*v)0.4.
Obrabotka Metallov / Metal Working and Material Science. 2017;(1):40-50
40-50
Surface alloying of titanium with aluminium by non-vacuum electron beam cladding of powder mixtures
Abstract
Titanium aluminides are promising materials for structural and high temperature applications. They possess low density and a high strength level which are very important properties for the aircraft. However, they have a range of disadvantages. Among them, there are low plasticity and crack growth resistance. One of the solutions which allow making use of beneficial properties of intermetallics consists in the formation of intermetallic layers on the surface of metallic samples. In this study the method of non-vacuum electron beam cladding of powder mixtures consisted of aluminium and titanium was used to obtain the surface layers reinforced with intermetallics on cp-titanium workpieces. Microstructure, microhardness and tribological properties of surface alloyed materials were investigated. An average thickness of coatings was about 2 mm. The microstructure of coatings was characterized mainly by formation of lamellar crystals. The maximum microhardness level of the coatings was about 600 HV. The reasons of microhardness increase consisted in the formation of titanium aluminides and action of the solid solution hardening mechanism. Phase composition of different clads varied from γ-TiAl to α-Ti according to Al percentage in the powder mixture. In comparison with cp-titanium the obtained materials possessed a lower level of a friction coefficient and a lower tendency to adhesion at a contact with a steel indenter. The best results obtained in the process of a sliding friction test were obtained for the Ti-Al(10/35) sample. It possessed 3-4-fold decrease of a friction coefficient compared to pure titanium. Relative wear resistance values obtained during interaction of samples with fixed abrasive particles correlated with their microhardness.
Obrabotka Metallov / Metal Working and Material Science. 2017;(1):51-60
51-60