No 2 (2014)
- Year: 2014
- Articles: 14
- URL: https://journal-vniispk.ru/1994-6309/issue/view/19983
- Description:
Full Issue
TECHNOLOGY
Development of preparation technology of the cutting tools for layered composite materials treatment
Abstract
Processing of composite materials is difficult due to the nature of its properties, resulting in an intensive wear of the cutting tool. Its cutting part should have a high strength and hardness, and small wedge angle. To meet these requirements, the cutting part of the tool is made of hard alloy, but the formation of the edge with the geometry results in poor quality products. The article proposes to form a cutting edge tool by honing with diamond wheels using electrochemical processes that facilitate the process of cutting. For this it is necessary to determine rational modes of combined electro-diamond grinding of hard alloys with specific cutting edge geometry. The relationship between surface roughness and specific consumption of the diamond wheel depending on the diamond wheel growing current density and etching details current density are received during laboratory tests. It is found that when increase electrical parameters of the grinding, roughness decreases to 0.1 microns and the specific consumption of the wheel increases to 2.3 mm3/mm3. It is shown that the combined method of electro-diamond grinding has advantages over other methods. The treated surface has a sufficient quality and quantity of chips at the cutting edge does not exceed 10 microns. Recommendations on the appointment regimes for sharpening of the cutting tools for composite materials treatment are offered on the basis of the research work.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):6-13
6-13
Reduction of residual stresses in mandrelled thick-walled cylinders
Abstract
The methodology and results of experimental studies on possibility to reduce residual stresses in the mandrelled cylinders of steel grade 45 (0.45% C) with 5 mm diameter hole and with a wall thickness ratios 2 and 3 by plastic tension are presented in the article. It is found that even when the axial tensile plastic deformation is 0.005 significant decrease in the district of residual stresses in these cylinders occurs; with deformation increasing up to 0.015…0.020 county residual stresses are reduced in magnitude from 140…500 MPa to 30 ... 50 MPa. The relationships calculated to estimate accuracy of diametric dimensions of the cylinders after plastic tension are given. It is shown that plastic tension of mandrelled cylinders reduces accuracy of holes with a diameter less than 5 mm by less than one accuracy grade. It is noted that the considered method of reducing residual stresses is the most appropriate to use in the manufacture of long cylinders.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):14-20
14-20
Prediction of microgeometry in pendulous grinding of plane parts made of steel 13Х15Н4АМ3 by high porous wheels
Abstract
The grinding process is used at the final stage of manufacture of responsible parts. The quality criterion in this case is surfaced roughness that determining machine durability. Abrasive wheels are the weakest link in process technology system, which cutting abilities can’;t be expressed as a deterministic quantity. In this connection the assessment of cutting properties of abrasive wheels is conducted with attraction of parametric and nonparametric statistical methods that allow to find not only expected measure of position (mean, median), but also a measure of scattering, estimated by deviations standards, swings and interquartile widths. The measures of scattering are seldom considered in estimating of cutting ability of abrasive wheel, although they only allow to characterize the stability of the process. This is especially important in processing of large operating batches of parts on customized machines. The research is conducted with high porous wheels (VPK) of new generation, which porosity was increased to (10-12)th structure and high-strength grains of cubic boron nitride (CBN50 100/80 СТ1 10К27 100-КФ40) and microscopical corundum (5SG 46I 12 VXP) are used. It is revealed that the difference between expected means and medians is in the limit of categorical variables (CV), and the most accurate estimates of process stability are obtained with deviations of standard. Grinding of flat parts made of steel 13Х15Н4АМ3 should be occurred with wheels made of synthetic corundum 5SG that allows to decrease the high parameters of roughness - 1,12-1,16 times higher (that means one CV) and increase the process stability in 1,04-1,06 times.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):21-30
21-30
The influence of the geometrical factor on the force parameters of deformation and evolutions of the compression front of porous materials
Abstract
The influence of geometric size of the holes of the perforated plate on the parameters of the process of its compression in an enclosed stamp is researched. The curves, characterizing the deforming force and the evolution of the compression front at different degrees of deformation are shown. Force increases as the compaction of material and essentially depends on the speed of the tool motion speed and parameters of contact between workpiece and instrument. The relative thickness of fully densified layer material increases with increasing of the strain rate. It was revealed that the geometric size of the pores with the same degree of porosity has no significant effect on the characteristics of the compression front propagation and force parameters of the deformation process.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):31-38
31-38
Development for measuring complex for diagnosis the quality of the treated surface in the metal cutting
Abstract
The dependences of the roughness versus the parameters of acoustic emission during needle milling, that allow to monitor the quality of the surface layer, replacement and adjustment of tool cutting in real time are received. Obtained dependences show that the average roughness at the minimum amplitude of the acoustic signal is minimized. The dependences of the treated surface hardness versus the diameter and length of the cutting elements (wire) of the needle milling tool, that allow to monitor the degree of cold work, are received. Obtained dependences allow us to conclude that the diameter of the cutting elements (wire) has a greater impact on the hardness of the hardened layer than its length. To achieve a minimum degree of cold work of the treated surface it is necessary to choose the cutting elements (wire) with a minimal length and diameter. A principal scheme of measuring complex for diagnosing the roughness and surface hardness during metalworking in real time is developed. Using developed complex allows to improve the surface quality, apply process needle milling in finishing operations.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):39-45
39-45
Selection of technological schemes and high-precision plasma cutting mode optimization for structural steels
Abstract
Problems of the high-precision plasma cutting technological scheme for structural sheet steels with thickness range from 0,5 to 30 mm are considered. Results of experimental research on plasma cutting mode optimization for 3 mm thick steel St 37-3 are presented with evaluation of cutting precision, surface quality and burr forming on the bottom edge. The accuracy of sheet materials cutting was estimated by cutting edge angle at the transverse sections, the surface quality assessed by roughness parameter. It is established that depending on material class for the chosen scheme, the required accuracy and cutting quality are provided by processing speed. Thus the perpendicularity deviation increase in cutting edge from 3,8º to 5,8º and roughness development from Ra = 1,75 µm to Ra = 3,2 µm occurs with the processing speed increase from 2,0 to 2,4 m / min while structural steel St 37-3 cutting. Loss of the cutting precision with increased processing speed is due to the increase of the temperature gradient over the cross section of the cut, which leads to uneven temperature field over the thickness of the cut. Deterioration of the cut surface roughness at the maximum speed is due to limitations in the development of gas-dynamic and hydrodynamic flow that participate in removal of products from the cutting zone of the melt, leading to their partial deposition on treated surface.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):46-55
46-55
EQUIPMENT. INSTRUMENTS
Study of efficiency of a steam generator for coolant supply
Abstract
The design of a steam generator for cutting fluids supply (in a steam phase) into the zone of metals machining is described in the article. Efficiency of the device is examined; dimensional wear-out of the instrument is defined as the result of external steel cutting by a hard-alloy instrument. The volume of the steam generator chamber is 0,32 dm3. Coolant-cutting fluid consumption is 0,8 l/h. Output steam temperature is about 90 ˚С. Operation efficiency of coolant-cutting fluids is different and does not depend on the base. The best efficiency of water-and-oil emulsions Pressoil, Emulisol T and half synthetic fluids Progress 13К and Ivkor is proved bu the study. The process of the instrument wear-out is influenced by triboactive additives contained in cutting fluids.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):56-61
56-61
Geometry and stress condition of the oriented abrasive grains with controlled form
Abstract
The efficiency of the polishing process is determined by the properties of abrasive grains, including its form and orientation in the body of the grinding tool. It is possible to improve the operational factors of the grinding instruments by ordering of the grain geometry, selection of the rational form and orientation of abrasive grains for specific processing conditions and parameters of the power load. To solve this problem the research technique for estimation of the abrasive grains front angle parameter and tension value parameter with the form and orientation parameters is proposed. The offered technique is successfully tested in practice. During the development of this technique the interrelation of the alumina abrasive grain front angle parameter with the form, orientation and wear parameters is found. It is established that the minimum values of the front angles are fixed at grains of an isometric form and tangentially oriented grains. The maximum values of front angles are fixed at the needle and lamellar grains oriented under angles Θ = 22,5° ÷ 45° to the cutting plane. The analysis of tension in the orientated alumina abrasive grains of various forms in cutting discs is also made. It is established that for cutting discs the rational angle of the abrasive grains orientation is about Θ = 67º30΄. Practical enquiry of the developed technique is made by carrying out the experiments for determination of ultimate strength of the orientated abrasive grains with a controlled form of various brands and sizes by monoaxial compression.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):62-77
62-77
Improving the efficiency of deep hole finish machining
Abstract
Machining of the deep holes is traditionally associated with the difficulties of the cutting tools performance assurance and quality of the machined surface. Wear of the deep holes drilling heads is responsible for dependence between getting holes with deviation dimensions and shape and the technical conditions for the production of parts. To solve this problem it is suggested to make finish machining of deep holes with application of the high-speed steel reamers, hardened by carbides, and having special construction for application on the deep hole drilling machine. The hardening process is realized by electro-spark treatment with the portable industrial device. To improve the efficiency of the reaming process, the combination of hardened and non-hardened reamer teeth is suggested. Field tests showed an improved the efficiency of hardened reamers working performance at deep hole machining operations.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):78-82
78-82
Intelligent design of carrying systems of serial metal-cutting machines
Abstract
Questions of practical use of the technology of intelligent design of carrying systems of heavy multi-purpose machines developed by us and design of other types of metal-cutting machines – horizontal coordinate-boring machine, single-standard turning-merry-go-round machine are considered. The technology has four stages: 1) calculation of all external forces and loads, 2) formation of the boundary conditions (force, kinematics) for individual carrier constructions, 3) solution to the problem of final optimal distribution of a material by the individual supporting constructions with the real cross-section, 4) dynamic analysis. Results of calculation are compared to known literature data for these machines, received by other methods. Divergences in results of calculation are a consequence of not full basic data on these machines, presented in literature. Possibility of spread of technology of heavy multi-purpose machines carrying systems design on other types of machines is confirmed. It is shown that in case of possibility of objective function formation in an explicit form, usage of the direct optimization methods leads to faster and adequate decisions.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):83-90
83-90
Modeling of the technological machines support systems
Abstract
The issues of modeling of the technological machines support systems with allowance for technological machines elastic vibrations caused by the compliance of units and limitations of amplitude values of frequencies are considered in the article. The aim of the work is to develop computational models of the technological machine support systems (for example, loom STB) and confirm the proposed computational model by experimental results. It is proved that the computational model of the support system for a loom filling the width of 190 cm may be recommended to determine the first frequency of natural oscillations for the whole range of machines of this type. It is shown that while designing of the machines’; frame works, speed modes of the main shaft operating frequencies and absence of possible resonances should be taken into account. Based on the analysis of machine arrangements of range looms STB the frequency spectrum of the flexural-torsional oscillations of the loom STB -190 support systems is calculated. Developed computational model is a universal range of technological equipment filling the width of 180, 190, 216, 220, 250, 330 cm.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):91-99
91-99
MATERIAL SCIENCE
Experimental studies of strain resistance of aluminum alloy АД0 in the undersolidus temperature range
Abstract
The strain resistance of the aluminum alloy АД0 during deformation in near solidus temperatures ranging between 540 and 640 °С and strain rates ranging between 0.06 and 1.2 s–1 are studied in the article. It is found that the strain resistance increases with the growth of strain. It can be due to the passing dynamic recovery that inhibits the start of the dynamic recrystallization. At the temperature ranging from 560 to 640 °С, the АД0 alloy has an abnormal behavior of the strain resistance curve. It is expressed in an inverse strain-rate dependence of strain resistance. This behavior may result in the barrier effect of blocking free dislocations by dopant atoms in the strain-rate range from 0.06 to 0.1 s–1.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):100-106
100-106
Influence of fusion treatment on parameters of a microstructure and thermal expansion of silumin with the various content of silicon
Abstract
Study of influence of fusion mixture and fusion treatment on the parameters of microstructure and temperature coefficient of linear expansion of hypoeutectic, eutectic and hypereutectoid silumin is conducted. The next ways of a fusion treatment are used: hydrogen charging by the wet fiber rock sponge, air purge, hydrogen purge, boiling in alkali solution. There was an additional air purge of silicon fusion mixture. It is established that fusion mixture and fusion treatment using studied regimes promotes structure modifying, increases volume fraction of eutectic and decreases the temperature coefficient of linear expansion of silumins. Fusion treatment leads to decrease of dendriric branches size of Al - 3 % Si, Al – 5 % Si и Al – 15 % Si alloys and to the silicium dispersion in the content of silumins euthectic of eutectic and hypereutectoid content. The most effective influence of fusion treatment oriented to decrease of the temperature coefficient of linear expansion and decrease of abnormal thermal expansion is observed for hypoeutectic silumins with carbon content of 3 and 5 %.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):107-116
107-116
Electron beam cladding of powder mixtures containing titanium and tantalum on specimens of steel 40Х
Abstract
Cladding of powder mixtures of titanium with graphite and tantalum with graphite on thick blanks of steel 40Х was realized by electron beam accelerator. The structural and tribological investigations of surface-hardened materials were carried out. It is shown that the cladding of powder mixtures containing titanium and tantalum by high-power electron beam injected into the atmosphere leads to the formation of high-quality hardsurfacing overlays. The thickness of coating reinforced by titanium and tantalum carbides is equal to 2.2 and 1.7 mm respectively. The volume fraction of titanium and tantalum carbides is 30 and 10 % respectively. The maximal microhardness level of cladded materials is 10 GPa. The maximal wear resistance level is registered during sliding friction for specimens reinforced by tantalum carbides. Under conditions of fixed abrasive particles coating, reinforced by tantalum carbides, has a higher resistance level. Under the influence of loosely coupled fixed abrasive particles "Ti+C" and "Ta+C" coating have the similar properties.
Obrabotka Metallov / Metal Working and Material Science. 2014;(2):117-126
117-126