Procedure for strenghtening edges of work members of tillers
FIELD: machine building.
SUBSTANCE: surface of back side of edge is heated with electric arc of reverse polarity by means of carbon electrode and successively cooled. Also, the electrode is transferred along a curvilinear trajectory formed with linear transfer along a sharp edge and with a rotation around vertical axis. Angular speed of electrode rotation is determined from the ratio: 3 V/R < w < 9 V/R, where w is angular rate of electrode rotation, rad/s; V is velocity of linear transfer, m/s, R is radius of electrode rotation, m. Arcing is carried out under a pulse mode. Duration and amplitude of current pulses per one revolution of the electrode is increased at moving away from the sharp edge and is decreased at approach to it.
EFFECT: obtaining strengthened layer with alternate cross section facilitating edge self-sharpening.
The invention relates to agricultural machinery, in particular to the manufacture of operating tillage machinery.
There is a method of hardening metal surfaces by RF patent 2025509, MKI SS 8/22, publ. 30.12.94, bull. No. 24, in which the surface temperature of the electric arc reverse the polarity of the carbon electrode to the melting temperature and subsequent cooling to temperatures of phase transformations, in which the plastic deformation of the surface of a cooled tool. To increase the hardness to HRA78-80 (HRC 52-58) the product is subjected to cold treatment.
The disadvantage of this method is that when the hardening of the blades of the working bodies of tillage machinery plastic deformation produced after melting and cooling to the temperature of phase transformations, violates the geometry of the bimetal blade, which leads to violation of the terms of samosatene, which is ensured by the presence of unilateral hard wear-resistant layer in conjunction with soft base of the working body. Another disadvantage is that the cold treatment requires additional refrigeration units, which leads to additional costs and increase the value of tillage machinery.
The closest in technical essence and the achieved is the result (the hardness of the hardened layer HRC 58-60 in conjunction with soft base HB 140-160) is the method according to A.S. 1171538, MKI C21D 5/00, publ. 07.08.85, bull. No. 29, Varan for the prototype, in which the reinforcement is subjected to a surface of the back side of the blade of the plow blade by heating with an electric arc reverse polarity of the current 180-200A using a nonconsumable carbon electrode with a diameter of 8-10 mm and subsequent cooling speeds of 400-500°C/s, for example, flowing water.
The disadvantage of this method is the low degree of stabilization of the profile of the blade wear due to the impossibility of obtaining on the edge of a blade of solid layer thickness, provided the conditions samosatene, as with a uniform burning electric arc melting the edge of the blade is much more intense than the melting of the thickened part, which leads to the cross-melting metal and the disappearance of the soft layer on the tip of the blade.
It is known that the main conditions of samosatene bi-metal blades are the following dependencies (Wear and increase durability of parts of agricultural machinery. Tkachev VLADIMIR. "Engineering". M. 1971. Str).
The thickness of the soft layer is determined by dependence
where δ - the thickness of the soft layer,
δm is the thickness of the solid layer,
km is the coefficient of strength of solid layer of 1.0 to 1.8.
The hardness of the hard layer is determined by dependence
where Hm is the hardness of the hard layer,
Nm - hardness of the soft layer,
k=3-5 - coefficient depending on the abrasive properties of the soil.
From the above it follows that if the condition Hm=3-5 Nm in a known way, the condition δ=1-1,8 δm, fails because with a uniform distribution of energy of the electric arc on the treated surface or at the edge of the blade is missing soft layer, or thickened portion of the blade thickness of the soft layer is more desired. Thus, stabilization of the blade wear is disturbed, which leads to a sharp increase in traction resistance and villablino tillage tools.
The technical effect is to increase the degree of stabilization of the profile of the blade working bodies tillage machinery in wear by creating a solid layer having a cross section providing conditions samosatene.
This technical effect is achieved by the fact that in the proposed method, including heating the underside of the blade arc reverse polarity using carbon electrodes and subsequent cooling, according to the invention the hardening produces a pulse current, a moving electrode is produced along a curved path formed by the line p is ramieniem parallel to the edge with a speed V (m/s) and rotation around the vertical axis with radius R (m) and angular frequency w (rad/s), the value of the corner frequency is within the range determined from the ratio of 3V/R < w <9V/R, and the duration and amplitude of the current pulses for one revolution of the electrode increases with distance from the edge of the blade and decreases when approaching him.
Comparative analysis of the prototype allows us to conclude that the claimed method differs in that the movement of the electrode over the surface of the blade is produced along a curved path formed by the linear movement parallel to the edge of the blade and the rotation around the vertical axis with an angular frequency, determined from the ratio of 3V/R < w < 9V/R, and that hardening is produced by a pulsed current, with variable duration and amplitude of pulses during one revolution of the electrode, the magnitude of which increases with distance from the edge of the blade, and decreases when approaching him.
Thus, the claimed technical solution to meet the criteria of the invention of "novelty."
To verify the conformity of the invention the term "inventive step", the applicant conducted an additional search of the known solutions to identify signs that match the distinctive features of the prototypes of the features of the proposed method and device. The search results showed that the claimed invention does not follow for professionals explicitly known ur is VNA equipment, namely, declared essential features are a new property - enhancing stabilization of the profile of the blade throughout the entire process of wear, due to the receipt of a hard layer, having a cross section providing maximum conditions samosatene according to the formula(1), (2).
Thus, the claimed technical solution meets the criterion of "inventive step".
The invention is illustrated by diagrams and drawings.
Figure 1 presents the location of the electrode over the hardened surface and cross section of the blade, providing conditions samosatene where:
δ1 - the thickness of the soft layer at the edge of the blade;
δ2 - the thickness of the soft layer in a thickened portion of the blade;
δm1 - the thickness of the solid layer at the edge of the blade;
δm2 is the thickness of the solid layer in the thickened portion of the blade;
Hm - hardness hard coating;
Nm - hardness of the soft layer;
R is the radius of rotation of the electrode.
Figure 2 presents a pie chart of the distribution of current pulses per revolution of the electrode, not the shaded part corresponds to the arc at the minimum current J1, point 0(2π) corresponds to the position of the electrode on the tip of the blade, the point π corresponds to the position of the electrode above the thickened part of the blade. T1, T2, T3 - duration current pulse.
On IG presents a detailed diagram of distribution of current pulses per revolution of the electrode. J2, J3 - amplitude pulses of electric current.
Figs.4, 5, 6, 7, 8 shows the trajectory of the axis of the electrode defined in parametric form, with X-coordinate corresponds to the linear movement of the electrode and is determined by dependencewhere t is time (s), and the Y coordinate corresponds to the transverse movement of the electrode and is determined by the dependence Y=R cos (wt). The X-axis corresponds to the line on which lie the centers of rotation of the electrode, and the maximum coordinate value +and-correspond to the radius of rotation of the electrode.
4 shows the trajectory with parameters w=3V/R.
Figure 5 presents the trajectory with parameters w=4,5V/R.
Figure 6 presents the trajectory with parameters w=6V/R.
Figure 7 presents the trajectory with parameters w=7,5V/R.
On Fig presents the trajectory with parameters w=9V/R.
The method is as follows.
Carbon electrode set on the edge of the blade and excite an electric arc at a minimum current J1, after the formation of the molten bath and the onset of stable arc start rotation of the electrode and pulse change of the electric current. After the formation of the molten bath across the width of the blades start rotating movement of the electrode parallel to the sharp edge of the blade.
Change the thickness of the firmly what about the layer (reduction at the tip of the blade and increase with distance from it) in this way reach the uneven distribution of energy of the electric arc in cross-section machined blade so most stands out on thickness portion of the blade, and lower on the tip of the blade due to the asymmetric trajectory of the electrode and of different duration and amplitude of the pulses arc, the trajectory of the electrode according to the invention allows uniform saturation of carbon in the molten metal due to repeated exposure to the arc on the same spot of the surface of the blade.
The graph in figure 4 clearly shows that the trajectory of the axis of the electrode represents asymmetric with respect to the X-axis curve. This is because above the X-axis translational and rotational motion occurs in the same direction, and below the X-axis these movements occur in the opposite direction.
The described movement of the electrode leads to the unbalanced distribution of energy of the electric arc in cross-section of the molten weld pool and, consequently, to different depths of fusion hardened surface that allows changing the parameters of the trajectory change and the degree of heat to harden the surface.
The range of parameters of the trajectory is limited by the fact that when the angular frequency (w), equal to and less than 3V/R (figure 4), uneven saturation of carbon in the molten bath, as mixing tubs practically does not occur is it that is, when the angular frequency (w), equal to and less than 3V/R, a solid education in the parcel layer with low hardness, which violates the condition of samozatachivanie (2).
With increasing angular frequency higher than 3V/R, but less than 9V/R (figure 5, 6, 7), there is an increase in the uniformity of the carbon saturation, because the arc is in the process of moving affects the same place hardened surface repeatedly, while reducing the effect of uneven distribution of energy of the electric arc in cross-section of the molten bath, the conditions of samosatene according to the formulas (1), (2) are performed.
With increasing angular frequency (w) to a value equal to or more 9V/R (Fig), the effect of uneven distribution of energy in almost disappears, which leads to the cross-penetration of a thin section of the blade.
The above trajectory parameters allow you to create the uneven distribution of energy in the range of 20-40%, therefore, to increase the effect of the uneven distribution of energy and increase the control range, the melting of the hardened surface is performed with pulse current (2, 3) with varying duration and amplitude of the pulse arc during one revolution of the electrode, which increases when you delete an arc from the edge of the blade and decreases when approaching not the at. In the intervals between the pulses of the electric arc burns at the minimum current (J1), which provides a stable arc and the desired depth of penetration of the thin part of the blade.
Change the current value for one rotation of the electrode leads to a change in the amount of carbon derived from carbon electrodes in the molten bath, however, the rotation of the electrode allows to increase the uniformity of saturation by repeated exposure to the same place hardened surface that provides at least 3% of carbon over the whole cross section of the solid layer.
Thus, modifying the trajectory of the electrode, the magnitude of the current pulses of the electric arc, as well as the number and duration of pulses, you can change the depth of penetration of the hardened surface and create a hard layer, having a cross section with variable thickness varying from a minimum at the tip of the blade to the maximum in the thickened portion of the blade that provides conditions samosatene.
The value of the minimum voltage, current and pulse duration, number of pulses per revolution of the electrode will depend on the characteristics of the power source of the electric arc, the radius of rotation of the electrode rotation speed and the moving electrode, geometric shapes hardened blades, sizes and weight ed the lia, as well as the conditions of heat removal from the hardened surface, so the choice of these values is empirically for each specific product.
For example, for the blade of the working body tillage tools with the following dimensions: the thickness of the thin part of the blade is 2 mm, the maximum thickening - 6 mm, length 16 mm, material - steel 20, HB 140-180 (HRC12-15), weight - 1.2 kg, copper heat sink plate, the hardening was carried out in the following modes:
the speed of linear movement - V=0.01 m/s;
angular frequency of rotation of the electrode - w=7,5 rad/s;
the radius of rotation of the electrode, R=0,004 m;
the electrode diameter is 8 mm;
minimum current - Jmin=150A;
maximum current - Jmax=230V;
the number of pulses per revolution of the electrode 3.
Synchronous rotation of the electrode and the change in the arc current was produced using a stepper motor. The synchronization of the number of steps of the motor and the number, duration and amplitude of the pulse arc current during one rotation of the electrode was performed with the help of electronic unit assembled on standard digital modules (counters, timers).
In the melting back of the blade and further cooling the flowing water resulting layer with a hardness of HRC 58-60, width of 20 mm and a depth of penetration: at the edge of the blade from 0.8 to 1 mm and 2.5 to 3 mm above the thickened part of that is otvetstvuet conditions samosatene according to the formulas (1), (2), that is, the thickness of the soft layer, as at the edge of the blade (δ1), and in the thickened part (δ2), is in the range from 1 to 1.6 thickness of the solid layer (δm1), (δm2), and the hardness of the hard layer (Hm) is in the range from 3.2 to 5 hardness soft layer (Nm).
The use of the present invention provides stabilization of the profile of the blade throughout the entire process of wear, which is 1.5-2 times increases structural durability of the working bodies of tillage tools and their turnaround time of service.
The method of hardening the blades of the working bodies of tillage machinery, including heating the underside of the blade arc reverse polarity using carbon electrodes and subsequent cooling, wherein the heating is carried out by a pulsed current, a moving electrode is produced along a curved path formed by the linear movement parallel to the sharp edge of the blade and the rotation around the vertical axis with angular frequency determined from the relation:
3 V/R<w<9 V/R,
where w is the angular frequency of rotation of the electrode, rad/s;
V - speed of linear movement of the electrode, m/s;
R is the radius of rotation of the electrode, m,
duration and amplitude of the current pulses for one revolution of the electrode increases with the distance from the sharp edges of the blade and reduce when is lizanie to him.
SUBSTANCE: tool is made from alloyed tool steel containing the following components in wt %: carbon - 2.00-2.20; chromium - 11.0-12.0; tungsten - 0.50-0.80; vanadium - 0.15-0.30; molybdenum - 0.60- 0.90. Stepped flat knife from alloyed tool steel is arranged on working face of cylindrical male mould along its lengthwise axis and features straight and skewed inward cutting edges. Distance between cutting edges and cylindrical male mould length exceeds maximum weld trimmer crosswise thickness. Cylindrical male mould and flat knife share outer surface with its diametre not exceeding minimum inner diametre of the tube with due allowance for tolerable height of nearby weld trimmer. Flat knife step height equal half the diametre of cylindrical male mould. Trimmer thermal processing includes hardening made in steps by preheating to 200-300°C and subsequent heating to 1020-1050°C salt bath, and one-run tempering at 400-500°C for at least 3 hours along with cooling in air.
EFFECT: tool higher life and reduced wear in producing drill pipe with welded locks.
2 cl, 2 dwg
FIELD: agriculture engineering; mechanical engineering.
SUBSTANCE: invention relates to heat treatment of duckfoot shovels. To increase wear resistance, tillage member, after heating to austenite state, is subjected to thermocyclic machining and at last cycle it is heated to austenite state with size of grain of 0.011-0.045 mm and is hardened to bainite structure, with heater enclosing working member over entire contour from side of blade, and after thermal treatment it is subjected to surface plastic deformation at angle of α=5÷65° to blade.
EFFECT: increased wear resistance of tillage members by 50%.
FIELD: mechanical engineering; welding production.
SUBSTANCE: the invention is pertaining to the field of mechanical engineering, in particular, to the welding production, mainly to manufacture and repair of the executive devices of agricultural machines. The technical effect of the invention is the increased service life of the executive devices of agricultural machines due to improvement of their strength characteristics and a wear-resistance to an abrasive wear. At short-time action on a component of a high intensity current - up to 16 kA in the welding machine MT-1614, as a result of a high heating appear the structural alterations caused by formation of quenching structures. Therefore the strength of the contact patch i.e. the heat-affected zone becomes considerably higher, then the strength of the parent metal. New in the given method is that for strengthening and as a consequence of it for increasing the agricultural machines executive devices components wear-resistance to the abrasive wear was usage of the electric welder МТ-1614. As a result of application of this method there is no need in the further machining or buying the dear alloying materials.
EFFECT: the invention ensures an increased wear-resistance of the agricultural machines executive devices components to the abrasive wear due to usage of the electric welder МТ-1614.
SUBSTANCE: cast iron is melt in electric furnace. At tapping into a ladle melt is modified at temperature 1370-1400°C with complex alloy consisting of silicon-barium at amount 70-80 % of alloy weight. Preliminary there are produced casts out of mottled iron with austenite-martensite matrix by casting into a raw sand-clay mould. To obtain austenite-ferrite structure in iron casts they are subjected to graphitising annealing at temperature 980-1100°C, to conditioning during 3-5 hours and to successive cooling with a furnace to room temperature.
EFFECT: high level of ductility and impact strength at sufficiently high durability of items out of cast iron.
FIELD: engines and pumps.
SUBSTANCE: invention relates to development of sliding components used in compressors. Sliding component (17, 23, 24, 26, 39, 60, 96, 310b, 524, 526, 644, 646, 724, 726, 734, 736, 817, 821, 823, 824, 825, 826, 827, 921, 924) of compressor features content of carbon varying from 2.0 wt % to 2.7 wt %, content of silicon varying from 1.0 wt % to 3.0 wt %, the rest making iron that contains unavoidable impurities. Metal structure represents, mainly, perlitic structure, ferrite structure and grain graphite. Metal hardness exceeds HRB 90, but is smaller than HRB 100. Smaller part of sliding component has high tensile strength.
EFFECT: longer operating life, fast running-in, no jamming in abnormal conditions.
18 cl, 64 dwg
SUBSTANCE: there is implemented melting of cast iron, its pouring into non-metallic forms, crystallisation of ingots and heating of ingot located in non-metallic mould in induction-arc furnace up to 1147-1300°C with isolation 0.2-0.5 hours.
EFFECT: upgraded hardness of cast iron ingot.
1 ex, 1 tbl
SUBSTANCE: casting is subject to thermo-cycling and successive heating in melted urea in interval of 135-150°C, then to holding during 10-20 min and cooling in air; also casting is heated to 980-1020°C in each cycle, held at this temperature for 5-15 min and cooled in water; amount of cycles comes to 3.
EFFECT: reduced linear expansion factor of casting.
1 ex, 1 tbl, 1 dwg
SUBSTANCE: cast-iron products are subject to thermal cycling with heating up to 900-950°C, with isolation during 0.5-1 h and following cooling in boiling water, herewith number of cycles is installed up to three.
EFFECT: reduction of coefficient of linear expansion of cast-iron product.
1 tbl, 1 dwg, 1 ex
FIELD: tube rolling.
SUBSTANCE: method includes casting of blanks out of alloy with contents of carbon 1.8-3.2% and chromium 30.0-35.0%, thermal aging, machining of surface of the blank to rough and finishing dimensions with a cutting tool, combining machining with heating of a machined portion; at that the surface of the machined potion is heated up to 600-800° C at a length of 3.0-3.5 mm with a plasma arc of current 60-160 A and power 12 kilowatt; the center of the heated portion is located in front of the cutting tool edge at a distance of not more, than 20 mm.
EFFECT: reduction of labour input at machining, upgraded accuracy of both geometric dimensions of a finished product and of micro hardness of the surface layer, and increased wear resistance of work holders not less, than two times.
FIELD: metallurgy, possibly improvement of properties of gray iron castings.
SUBSTANCE: method providing decreased volume content of graphite, disintegration of graphite inclusions and their uniform distribution along cross section of castings comprises steps of heating and cooling in each cycle while heating in each cycle is realized till 700 - 750°C and then casting is cooled in water. Number of cycles is equal to 2 - 4.
EFFECT: possibility for providing decreased volume content of disintegrated and uniformly distributed graphite in cross sections of castings.
1 ex, 1 tbl
FIELD: metallurgy, possibly improvement of properties of gray iron castings.
SUBSTANCE: method providing decreased volume content of graphite, disintegration of graphite impurities and their uniform distribution along cross section of castings comprises steps of heating and cooling gray cast iron in each cycle while cast iron is heated in each cycle till 980 - 1020°C and further it is cooled in water. Number of cycles is equal to 2 - 4.
EFFECT: decreased volume content of graphite, disintegration of graphite inclusions and their uniform distribution along cross section of castings.
1 tbl, 1 ex
FIELD: processes for heat treatment of cast iron parts with spheroidal graphite.
SUBSTANCE: method comprises steps of testing initial structure by means of coercive force meter and selecting heat treatment modes on base of testing results. Parts are subjected to austenization at 880 - 930°C; interim cooling of parts in furnace till temperature in range Ar3 - Ar1 ; cooling at rate 5 -10°C per minute till temperature in range between temperature of starting A - P conversion and temperature exceeding by 50°C maximum-stability of temperature of austenite being converted to upper bainite or troostite. Then part is subjected to isothermal soaking at such temperature till maximally possible degree of A - P conversion. After cooling structure is inspected by means of coercive force meter for detecting tendency of pearlite and tempered bainite to changes at further nitriding. Depending upon inspection results tempering mode is selected and after such tempering final testing of structure by means of coercive force meter is realized according to index values of scale developed on base of investigating relationship of readings of coercive force meter from initial structure and its changes at nitriding process and also from growth and warping of parts at nitriding.
EFFECT: possibility for producing stable structure resistant against changes at nitriding process.
2 cl, 1 ex
FIELD: ferrous metallurgy, namely production of high-strength cast irons with spheroidal graphite, possibly production of cast products having high strength, ductility and impact viscosity.
SUBSTANCE: cast iron contains, mass%: carbon, 3.28 - 4.03; silicon, 2.34 - 3.62; manganese, 0.22 - 0.53; copper, 1.16 - 2.34; molybdenum, 0.21 - 0.52; magnesium, 0.02 - 0.05; barium, 0.03 - 0.08; rare-earth metal, 0.02 - 0.06; iron and inevitable impurities, the balance. Cast pieces of such cast iron are subjected to heat treatment comprising stepped austenization at heating up to 820 - 830°C; soaking for 0.5 h and further heating till 870 - 900°C and soaking for 0.5 - 1.5 h. Then castings are cooled till temperature less than 500°C. Cooling rate is controlled depending upon wall thickness of cast piece. If wall thickness is less than 20 mm, cast product is cooled in air; if wall thickness is 25 -40 mm cast product is cooled in water for 4 - 5 s; if wall thickness exceeds 40 mm cast product is cooled in water for 6 - 10 s. Then casting are subjected to thermocycling in temperature range 270 - 390°C for 1.5 -3 h and to air cooling.
EFFECT: improved stable mechanical properties of castings with different wall thickness.
2 cl, 2 dwg
FIELD: metallurgy; production of ingots made out of mottled cast iron with austenitic-bainite structure.
SUBSTANCE: the invention is dealt with metallurgy, in particular, with development of a method of production of mottled cast irons with globular graphite, which may be used for manufacture of components being worn under action of increased loadings. The method provides, that the mottled cast iron is melted down in the induction furnace, the liquid melt at pouring into a ladle is modified with magnesium-bearing addition alloys for formation of the ball-shaped graphite impurities in the ingots and during casting into a sandy-argillaceous mold expos it to inoculating modification. The ingots after crystallization are pulled out from the molds at the temperature of 900-1000°C, transposed to a furnace with temperature of 950-1000°C and keep there during 10-30 mines. After the aging the ingot is exposed to quenching in an isothermal bath at the temperature of 300-320°C within 1-1.5 hour. At that they use the cast iron of following chemical composition, (in mass %): carbon - 3.2-3.4, silicon - 3.0-3.3, manganese - 0.3-0.4, magnesium - 0.04-0.07, molybdenum - 1.5-1.7, nickel - 2.2-2.6, sulfur - 0.01-0.012, phosphorus - 0.06-0.08, iron - the rest. The invention allows to obtain a mottled cast iron with globular graphite and austenitic-bainite structure, high impact resistance, strength, hardness, wear resistance and quasi-isotropy.
EFFECT: the invention ensures production of a mottled cast iron with globular graphite and austenitic-bainite structure resistant to wear under action of increased loadings.
FIELD: metallurgy; deformation thermal treatment of iron-carbon alloys; manufacture of hot-deformed seamless tubes.
SUBSTANCE: proposed method includes preliminary heat treatment of high-strength cast-iron billet at temperature Ac3+200°C continued for 10 h and followed by heating the billet at deformation temperature, deformation of billet and heat treatment of tube.
EFFECT: improved quality of tubes; extended field of application of this method.
4 cl, 2 ex