Method of heat treatment of tram bandages
(57) Abstract:The invention relates to heat treatment of ferrous metals and can be used in the manufacture of wheel rims made of carbon steel for tramway rolling stock. The technical result is the provision of modes protivogololednoy processing tram bands in unheated wells, as well as narrowing of the temperature interval between rolling and marking tires. The method includes rolling and marking tires in a hot state, isothermal aging in unheated wells, slow air cooling. What's new is that between rolling and marking the temperature of the metal bands stand in the range of 840 - 880oWith, and the process is isothermal aging is carried out for 0,8 - 1,1 h at 500 - 650oWith subsequent slow cooling to 250oC. The invention relates to heat treatment of ferrous metals and can be used in the manufacture of wheel rims made of carbon steel for tramway rolling stock.Tram bandages, and rings made of medium-carbon steel, is made by rolling in a hot state upset and stitched the Ute small (compared to car tires) dimensions - the diameter of 700 mm, width and wall thickness in the range of 90 and 60 mm, weight up to 100 kg, the technology used to manufacture locomotive tyres for railway transport (diameter greater than 1000 mm, width: 145 mm, thickness 90 mm, weight about 450 kg) leads to increased culling platinum and large gradient properties of the metal in various parties.As a prototype adopted a method of heat treatment of bandages  , which involves the following process steps: heating of the billets to a temperature of 1250oC, upsetting the smooth plates, and justify the firmware of the center hole, rolling at a temperature of 850 - 1050oC, branding on the lateral surface at a metal temperature of 800 - 1000oC, a collection of bandages on the feet of 20 pieces and installing them in an unheated wells at a temperature of 300 - 400oC for slow cooling. Such technology in the manufacture of small tram bandages minor mass leads to the analysis of the properties of the metal - temporary resistance from 75 to 95 kgf/mm2the relative elongation of 8 to 14%, the hardness of 230 - 250 HB, and requirements of the consumer properties similar to higher limits specified values. Therefore, up to 15% Bandarenka the absence of isothermal processing results, despite the small cross section of the brace to the culling of up to 2.5% platinum.Thus, the use of known technology of heat treatment of tram bandages leads to great financial losses in the form of increased marriage on the properties and platinum and low resistance tyres in operation.The objective of the proposed method of heat treatment of tram tires is providing modes protivogololednoy processing tram bands in unheated wells, as well as narrowing of the temperature interval between rolling and marking tires.The problem is solved due to the fact that in the method of heat treatment of tram bands, including the rolling and marking in a hot state, isothermal aging in unheated wells, slow cooling in the wells and air cooling between rolling and marking the temperature of the metal bands stand in the range of 840 - 880oC, and the process is isothermal aging is carried out for 0.8 to 1.1 hours at a temperature of 500 to 650oC followed by slow cooling.The proposed new technology of heat treatment tram bandageoC, the sediment at the press force 3200 ie, smooth plates, justify and firmware of the Central hole in the workpiece, rolling and marking bands on the lateral surface, the temperature of the tyres between rolling and marking is maintained in the range of 840 - 880oC. Here are significant as the selected range, and place in the technological chain of control: the temperature of the end of the hot deformation has a significant impact on the size distribution and its properties, while the lower chapel (840oC) associated with the possible formation of microcracks in the places of drawing marks (minimum allowable temperature for this reason), and the upper limit (880oC) ensures virtually 100% yield tires on the mechanical properties of the metal. The selected location of the temperature control between the rolling and the stigma associated with the ability to regulate this temperature bandage-rolling mill and between the rolling mill and lamiales. Then the bands gather at the foot of 20-25 pieces and placed in cold, but warmed up to a temperature of about 400oC wells. The temperature in the wells with the footsteps of bands with temperature 700oC is aligned to a temperature of 600 - 650oC and within 0.8 to 1.1 Cassia hydrogen range 650 - 500oC. As shown by the experiments, this time isothermal exposure for section 60x90 mm medium carbon steel is enough to reduce scrap tires on platinum from 2.5 to 0.6%. The lower range of the exposure time (0.8 hour) corresponds to the banding steel with a carbon content of 0.6% or less, and the upper (1.1 hours) - for steel, carbon 0.7% and more. Subsequent cooling of the stop bands together with the well to a temperature of 250oC provides the minimum distortion profile tires.Thus, the use of the proposed method of heat treatment of tram bandages provides a mode protivogololednoy processing in unheated wells with the exception of marriage platinum, and the narrowing of the temperature range and its control between rolling and marking it helps to enhance the mechanical properties of metal bands.Example. In the manufacture of tram bands of steel with a carbon content of 0.7%, an outer diameter of 716 mm, a width of 88 mm, an inner diameter of 594 mm and a weight of 97 kg initial workpiece weight 125 kg was heated in a methodical and chamber furnaces to a temperature of 1250oC, two systems smooth plates on the press 3200 ie, and at the same press after RA is Ali the temperature of the metal, which regulate the supply of cooling water. The final temperature level bands 840 - 880oC regulated before marking with air baths. After marking the bands gathered at the foot of 20 pieces and metal temperature of about 700oC was placed in an unheated wells that previously using the gas nozzle was heated to a temperature of 400oC. Exposure bands in the wells was carried out at a controlled temperature of 650 - 500oC for 0.8 hours. With decreasing temperature below 500oC until the expiration of the specified time the well is heated by a gas burner. Then the bandages slowly cooled together with the well to a temperature of 250oC. the party into 240 pieces of experimental - industrial batch of tram bandages on platinum marriage was not, in the interim resistance rejected 2 of the bandage.Literature
1. Shifrin, M. Y., Solomonic M. I. Production of solid-rolled wheels and tires. - M.: metallurgy, 1954, S. 474-484.2. USSR author's certificate N 619265, 1978.3. The production of tires and tracks. Technological instruction JSC "NTMK" TI 102 - P. SP - 41. - S. 54-66. Method of heat treatment of tram bandages, including procate in wells and air cooling, characterized in that between rolling and marking the temperature of the metal bands stand in the interval 840-880oC, and the process is isothermal aging is carried out for 0,8-1,1 h at 500-650oC followed by slow cooling to 250oC.
FIELD: heat treatment of parts made in form of bodies of revolution from metal materials; cooling of monoblock wheels, tires, wheel discs and similar discs and rings such as railway wheels and tram wheels, gear wheels and sprockets.
SUBSTANCE: first, scale is removed from one and the same device by one and the same method to improve its mechanical properties and then mechanical properties are determined and reproduced through complex cooling performed in functional zone; cooling processes are different for different sections; parts are cooled at control or adjustment in "on-line" mode due to spraying or blowing-off by one cooling medium.
EFFECT: enhanced efficiency.
27 cl, 2 dwg
SUBSTANCE: invention relates to thermal treatment field. For providing of solidity not less than 300 HB on depth not less than 50 mm from surface of volution wheel tread, exclusions during the process of cooling of formation of hardening structures and providing of maximal drop of residual voltage, solid-rolled wheels made of steel with carbon content no less than 0.60 wt % is heated till the austenitising temperature and intensively cooled, at that during the cooling process from the moment of the beginning for 50-100 seconds it is implemented increasing of cooling intensity of comb roll surface and side surfaces of crown by all height from 0 till value 2-3 W/(cm2·s), then it is cooled during 40-300 sec with constant refrigeration rate of specified wheel face equal to value 2-3 W/(cm2·s) for providing of strengthening in all crown volume.
EFFECT: providing of material strengthening.
2 dwg, 3 tbl
SUBSTANCE: wheel pair is installed and fixed in rotating facility. Matte coating eliminating reflection of laser beam is applied on surface subject to treatment with CO2-laser. Focusing system is adjusted so, that diametre of laser radiation spot corresponds to a chosen mode. Required rates of wheel pair rotation and laser beam transfer are set by means of program controlled device. Compressed air blows off a flare of products of combustion into exhaust ventilation; laser treatment is carried out under a chosen mode to obtaining geometry of paths of laser strengthening eliminating melting zones of thermal effect and mutual overlapping of laser strengthening paths.
EFFECT: increased wear resistance of roll surface and crest of wheel pair due to increased hardness and due to obtaining high dispersed structure of strengthened zone.
SUBSTANCE: plasma surface hardening is performed by plasma generator with work gas flow converter that has slit-like outlet. Flow converter face surface is made to fit processed part shape. In processing, slit-like outlet is located at α=30-60° to generatrix of converter face surface. Processing is performed with overlap of processing strip, overlap length making l≥h·-tgα, where h is the processing strip width.
EFFECT: notably reduced extension strain, higher efficiency of surface hardening.
2 cl, 2 dwg
FIELD: machine building.
SUBSTANCE: metal surface strengthening is carried out by means of low temperature plasma arc of direct action. As plasma generating gas there is used argon, mixture of argon with helium, and mixture of argon with carbon containing gases. Also, heating is performed with magnetic oscillation of arc with triangle shape of voltage pulse, scanning amplitude 20-45 mm and distance of treatment 10-30 mm. A strengthened surface layer consists of several sub-layers: at depth of 0.2-0.8 mm - structure of martensite with inclusions of upper bainite, - from 0.8 to 1.8 mm - trosto-martensite structure, - from 1.8 to 2.5 mm - sorbitic-martensite structure, - from 2.5 to 3 mm - sorbite, - over 3 mm - ferrite-pearlite structure of basic metal.
EFFECT: raised efficiency of strengthening process, 3 times increased wear resistance of strengthened working zone of wheel, 3 times reduced probability of development of hydrogen metal brittleness and tendency to brittle fracture.
2 cl, 1 tbl
SUBSTANCE: cooling of working layer of rim during the first 180 sec is performed at discrete increase in flow rate of cooler of 0.0005 to 0.02 l/(cm2/s) by 0.0001 l(cm2/s) every 15-30 sec and the next 120 sec at constant flow rate of cooler to 0.5 l/(cm2/s), and cooling of end surface of rim on the ridge side is performed with air with flow rate of 0.5 m3/(cm2/s); then, wheel is cooled in the air and tempering is performed.
EFFECT: high application properties of railroad wheels owing to improving wear resistance of working layer of wheel rim and mechanical properties of wheel disc; heating to austenisation temperature and differentiated cooling of working layer of rim and its face on the ridge side is performed during 300 s.
1 ex, 2 tbl
SUBSTANCE: hardening is performed at 810-850°C. Tempering is performed at 450-500°C. Then, plasma treatment with plasmotron with energy density of 106-108 W·m-2 is performed. Nitrogen is used as plasma-forming gas. Plasma treatment of tread contact surface and wheel flange surface is performed. Transformer of working flow of plasma-forming gas, which is profiled as to shape of treated surface, is used. Wheel is rotated during treatment about its axis at certain speed. Wheel rotation speed is determined as per ratio n=K·(1/Dw), where n - speed of wheel rotation about its axis, rpm; K - empirical coefficient equal to 20-2000 revolutions·mm/min; Dw - diameter of treated wheel, mm.
EFFECT: increasing strength and thickness of reinforced layer; improving quality and efficiency of plasma strengthening process; simplifying the process diagram of strengthening plasma treatment.
2 dwg, 1 ex
SUBSTANCE: first, wheel is heated for formation of austenite in all sections of a rim and a disk. Then, wheel is cooled for formation of bainite/martensite microstructure in the disk section. Wheel is cooled for formation of bainite/martensite microstructure in the rim inner section. Wheel is cooled for formation of bainite/martensite microstructure in the rim outer section.
EFFECT: providing required mechanical properties of steel and increasing wheel service life.
10 cl, 7 dwg, 1 tbl
FIELD: process engineering.
SUBSTANCE: invention relates to thermomechanical processing of parts and can be used for surface hardening of friction working surfaces of rails and rolling stock wheels. Particularly, it relates to surface hardening of wearing surfaces of parts, primarily, rolling surfaces and railway mounted axle flanges. Strips with modified structure are produced that feature mechanical properties other than those of mother metal. Note here that said strips vary in width and depth over the wheel flange circle.
EFFECT: higher wear resistance, longer wheel life.
1 tbl, 7 dwg, 1 ex
FIELD: process engineering.
SUBSTANCE: invention relates to metallurgy, particularly, to heat treatment of binding bands. Railway bands made of steel containing the components that follow are subjected to heat treatment: C 0.65-0.75 wt %, Mn 0.6-0.9 wt %, Si 0.22-0.45 wt %, Cr 0.2-0.6 wt % and V 0.01-0.03 wt %. Band is heated to austenising temperature and subjected to controlled cooling nu liquid coolant or air-water mix, surface cooling being performed by water with controlled flow rate: 0.00035 l/(cm2·s) for up to 120 s, 0.00075 l/(cm2·s) for 121-150 s, 0.00115 l/(cm2·s) for 151-180 s, 0.00155 l/(cm2·s) for 181-210 s, 0.002 l/(cm2·s) for 211-300 s. Note here that side surface in the band inner diameter is air cooled with flow rate of 0.0003 m3/(cm2·s) with subsequent holding in air and tempering.
EFFECT: higher wear resistance of working play, contraction strains in working ply to 50-60 mm depth from rolling surface.
5 tbl, 1 ex