Method of production of triblets of pilgrim-step rolling mills

FIELD: metallurgy; pipe rolling.

SUBSTANCE: the invention is pertaining to the field of pipe rolling, in particular, to the methods of production of triblets of pilgrim-step rolling mills and may be used at production of triblets of pilgrim-step rolling mills for rolling of hot-rolled pipes of large and average diameters (273-550 mm). The method provides for casting of steel ingots, production of triblets out of the steel ingot blanks by, a heat treatment of the triblet ingot blanks, their mechanical working to obtain the finishing dimension with subsequent hardening by a roller run, casting of carbon steel ingots, application by surfacing on the ingot blanks of a heat-resistant and abrasive resistant layer and production of triblets out of the steel ingots by the pilgrim-step rolling, and in the process of operation after appearance of a net flame erosion cracks conduct a triblet multiple remachining till removal of the heat-resistant and abrasive resistant layer, application of a new heat-resistant and abrasive resistant layer by surfacing, machining till the finishing dimension and hardening by a roller running and determination of the thickness of the heat-resistant and abrasive resistant layer from the following equation Δ = A*µ* (l÷D/S*K), where: A - is the minimal thickness of the surfacing layer after the final mechanical working of a triblet and equaled to 10 mm; D - the maximal diameter of the pipes rolled on the given triblet, mm; S - the minimal wall thickness of the pipes rolled on the given triblet, mm; µ - a reduction ratio at rolling of ingots into the hollow triblet blanks and K - a coefficient equal to 0.02. The invention ensures production of triblets of pilgrim-step rolling mills for rolling of hot-rolled pipes of large and average diameters, usage as the basis of the triblet ingot blanks produced out of a carbon steel instead of alloyed steel, increased resistibility of triblets and as a result of it a decreased share of cost of the technological tools in the cost of production of pipes.

EFFECT: the invention ensures production of triblets of pilgrim-step rolling mills for rolling of hot-rolled pipes of large and average diameters, usage of carbon steel in production of triblet ingot blanks, increased resistibility of triblets, decreased share of triblets cost in the cost of the pipes production.

2 cl, 1 tbl

 

The invention relates to pipe production, namely the method of manufacturing technology tool and can be used in the manufacture of mandrels piligrimage mills for rolling hot-rolled pipes of large and medium diameters (273-550 mm).

A known method of manufacture of mandrels piligrimage mills for rolling hot-rolled pipes of large and medium diameters, including the casting of ingots of steel grade LED1 (50HN) with a chemical composition according to GOST 4543-71, forging them into a cylindrical billet (forgings) with ukonom 2,25-2,5, rough machining with allowance on a diameter of 10-15 mm taking into account leashes forgings during heat treatment, heat treatment domowych blanks, machining of dies to finish size with subsequent hardening by rolling a roller or grinding surface and exploitation to education grid razgonnyj cracks "waves" or longitudinal cracks (Faganello and other Hot tube rolling, metallurgy. Moscow. 1962, s-356. The report on theme: 22-V-13-541-73: "Development of technology for manufacture of mandrels increased wear resistance and their introduction into production at the Chelyabinsk pipe rolling plant", Dnepropetrovsk, 1975. TA 158-148-98 "Technological process of machining the guides and work roll piercing mill, mandrels and piligrimage rolls in the shop №1 JSC "Chelyabinsk tube rolling plant").

The disadvantage of this method I have is that what Dorn fail, for "wave"' (bumps), surface rashanim ring cracks and rough longitudinal cracks, and uneven abrasion of their length (the loss of the geometric dimensions). As a rule, during rolling of pipe diameter and 426 377 mm on the mandrels of steel grade LED1 main defect is the "wave" (bumps). "Wave" on the surface of the mandrels occurs at a distance of 1500-2000 mm from domowego castle. "Wave" is a plastic deformation of the surface layers of metal mandrels, which is caused by heating their surfaces to a temperature above 650°and caused by prolonged contact of the cartridge-tubes and mandrels or rolling of two or more sockets on the same mandrel without cooling. When rolling pipe size 426×9×32000-35000 mm, the contact time of the mandrel with the sleeve-tube is from 5.0 to 6.0 minutes. During this time, the mandrel on the site 1500-4000 mm from the castle part is heated to 650°C. the Highest temperature of the mandrel is in the area from 2000 to 3000 mm from domowego castle, i.e. the Central part. The resistance of the mandrels on the "wave" is in direct dependence on the instructions for their operation.

Ring cracks are associated with poor machining, the presence of hubs voltage (undercuts and grooves from the incisors). Coarse longitudinal crack depth of 1/3 to 3/4 of the radius of the mandrels are a consequence of the low the values of the plastic properties and impact toughness of the steel at cyclic temperatures.

There is also known a method of manufacture of mandrels piligrimage stew of steel grade DM2 (MF)with the following content elements: carbon - 0.24 to 0.32 per cent, manganese - 0,3-0,6%, silicon 0.15 to 0.40 per cent, chromium - 1,6-1,9%, molybdenum - 0,6-0,9%, vanadium - 0,15-0,25%, Nickel up to 0.5%. Dorn made of this steel is more durable. The resistance of their 1.2-1.3 times higher than that of steel LED1 (Report on: 23-V-13-81 /19-72/ P2 - PP "Finding steels with improved thermal stability and development of composite structures vilgerdarson". The Ural research Institute for the pipe industry. Ufa aviation Institute. Chelyabinsk pipe-rolling plant, Chelyabinsk, 1972).

However, the known method also has disadvantages. Dorn with a carbon content of 0.24 to 0.32 per cent fail mainly because of the appearance on their surface razgonnyj cracks and uneven wear along the length (the loss of the geometric dimensions). Asgarnia cracks occur due to thermal and structural stresses in the surface layer Dorin, which are heated by contact with hot shells-pipes to a temperature of Ac1-AC3 (650°C and above). Education grid razgonnyj cracks are the result of irreversible structural changes (shear deformation within the grains, grinding grains, the formation of voids, the deformation at the grain boundaries and the formation of submicroscopic tearing and damage of the surface layer). Termostaatsegisti surface is the cause of the first foci of destruction, initiating further development of cracks. With increasing number of cycles of heating and cooling increases the number and size of cracks, the cracks are connected and intertwined, forming a so-called "grid". Education grid razgonnyj cracks on the surface of the mandrels accelerates wear and loose metal particles. In the cracks of the intense oxidation of the metal and the processes of their wedging. A decisive influence on the life of the mandrels has the intensity of development of the grid razgonnyj cracks in larger, which is a criterion for rejection of the mandrels.

The closest technical solution is the method of manufacture and operation of the mandrels piligrimage mills for rolling hot-rolled pipes of large and medium diameters, including the production of conical electroslag ingot of steel DM2-III and its subsequent radial forging of a cylindrical billet having a castle and a working part, and forging its working parts are carried out with a linear increase okovki in the direction of the locking parts when the ratio of the maximum okovki to a minimum of 1.26-1,56, annealing of workpieces and drilling holes with a diameter of 100-105 mm (Patent RF №2055660 from 10.03.96,, bull. No. 7, p.34 and Avigliano, Limblines, Ldesign and other "New technology for the production of hollow mandrels piligrimage mills", Steel, No. 9, p.55-56, 1997).

However, the known method has also disadvantages. The resistance of the mandrels increased 1.2-1.4 times compared to the existing, but they also fail longitudinal cracks and the grid razgonnyj cracks, and the costs in the cost of pipe from 2.5 to 3.0%.

The technical result of the method is to increase the resistance of dies for rolling hot-rolled pipes of large and medium diameters, the cost reduction due to the replacement of steel HM steel 20 for manufacturing domowych blanks, followed by repeated application of (type SVHN) heat-resistant layer by deposition and subsequent running. The technical result is achieved by the fact that in the known method of manufacture of mandrels piligrimage mills for the production of hot-rolled pipes of large and medium diameters, including the casting of ingots of steel, getting domowych blanks, heat treatment domowych blanks, machining of dies to finish size with subsequent hardening by rolling the roller, the ingots cast from carbon steel, the surface of the ingot is applied by the welding heat-resistant layer and is obtained from the ingot billet mandrel by piligrimages rolling, and in the process of operation after the appearance of the grid razgonnyj cracks produce multiple grinding mandrel to udaleniya theplot is icogo wear-resistant layer, application of new heat-resistant layer by welding, machining to finishing size and hardening of the rolling roller, and the thickness of the heat-resistant layer is determined from the expression

Δ=A*μ*(1+D/S*K),

where a is the minimum thickness of the deposited layer after finishing the machining of the mandrel equal to 10 mm;

D is the maximum diameter of the pipes, rolled on the mandrel, mm;

S - the minimum wall thickness of pipes, rolled on the mandrel, mm;

μ - drawing ratio during rolling of ingots in the hollow mandrel semi-automatic workpiece;

K - coefficient of 0.02.

Dorn in the process are subjected to repeated cyclic heating and cooling. In addition to thermal impact of the mandrel exposed to the pressure rolls piligrimage mill and longitudinal stretching caused by the friction forces of the deformable metal during rolling and extract the mandrels of the pipe feeding apparatus. Because of the variability of the deformation zone for one revolution of the rolls, the pressure on the mandrel and the effect of friction forces are constantly changing. The complexity of the operating conditions of the mandrels is long finding them in contact with the heated plastically deformable metal, the lack of cooling in the deformation process, large temperature changes of the working surface of the mandrels in one C is CL (cooling to a temperature of 180-200° With the bath water and grease, heat in the rolling process and work within 3.5-6.0 minutes at a temperature of 500-650°). Joint action of high temperatures and pressures lead to the rapid release of the mandrels of the system, mainly on the grid razgonnyj cracks. Asgarnia cracks on the surface of the mandrels begin to appear through 0,80-0,85 from their initial resistance, which then begin to progress, grow, both qualitatively and quantitatively, i.e. in breadth and depth. At this point, the mandrel is forcibly withdrawn from service and permacoat to remove the deposited heat-resistant layer. After regrinding on Dorn put a new heat-resistant wear-resistant layer of a thickness of Δ1produce machined at the finishing size of the subsequent polishing or padding the running roller and return the mandrel in the production cycle. Dorn after regrinding and application of new heat-resistant layer operate until (inception) grid razgonnyj cracks. The cycle is repeated, that is, they withdraw from the process, permacoat to remove the heat-resistant layer, put a new heat-resistant wear-resistant layer, mechanically treated on a fair size with subsequent hardening roller.

Thus, the mandrels blocks the comfort to failure for reasons not related to rzhanymi cracks (failure of the mandrel, the wear of the castle and so on).

Comparative analysis of the proposed solutions with the prototype shows that the inventive method of manufacture of mandrels piligrimage mills for the production of hot-rolled pipes of large and medium diameter differs from the known fact that the ingots cast from carbon steel, the surface of the ingot is applied by the welding heat-resistant layer and is obtained from the ingot billet mandrel by piligrimages rolling, and in the process of operation after the appearance of the grid razgonnyj cracks produce multiple grinding mandrel to remove the heat-resistant layer, application of new heat-resistant layer by welding, machining to finishing size and hardening of the rolling roller, and the thickness of the heat-resistant layer is determined from the expression

Δ=A*μ*(1+D/S*K),

where a is the minimum thickness of the deposited layer after finishing the machining of the mandrel equal to 10 mm;

D is the maximum diameter of the pipes, rolled on the mandrel, mm;

S - the minimum wall thickness of pipes, rolled on the mandrel, mm;

μ - drawing ratio during rolling of ingots in the hollow mandrel semi-automatic workpiece;

K - coefficient of 0.02.

Thus, the inventive method is relevant to the duty to regulate the criteria of the invention of "novelty."

Comparison of the proposed method of manufacture and operation of the mandrels not only prototype, but also with other technical solutions in this field of technology is not allowed to reveal in them the features distinguishing the claimed solution to the prototype that allows to conclude that the criterion of "substantial differences".

The method was tested on pipe installation piligrimage mills 8-16" JSC "Chelyabinsk tube rolling plant". The production was set two new mandrel diameter 409/410 and 309/310 mm, made by the existing and proposed technologies. Data on the resistance of the mandrels piligrimage mills made by the existing and proposed technologies listed in the table. The table shows that the average resistance of the mandrels with a diameter of 409/410 mm, manufactured and operated according to the existing method is 1,100 tonnes of pipe size 426×9 mm, and the diameter mandrels 309/310 mm - 800 tonnes of pipe size 325×9 mm mandrel according to the new method were made on the following technology: bullion 20 size 420×2000 drilled Central hole with a diameter of 150±5.0 mm, and bars of size and h mm Central hole with a diameter of 100±5.0 mm, then these ingots way of surfacing was applied heat-resistant wear-resistant layer (SVHN) thick, respectively, 60,0 55,0 and mm, the Ingot was heated in the reheating furnaces on the temperature 1270-C. Ingots size h was stitched in the piercing mill in sleeves size HH mm mandrel diameter of 200 mm and were rolled on piligrimages mill in the hollow mandrel semi-automatic billet size 430×120×5500 mm mandrel diameter 189/190 mm Ingots size 540×150×2000 mm after heating without firmware was applied to programowy the camp and rode mandrel semi-automatic billet size 330×100×5850 mm diameter mandrels 129/130 mm After rolling mandrel semi-automatic billet was subjected to heat treatment, straightening and mechanical processing on the finishing size, respectively, 309/310 and 409/410 mm On the mandrel diameter 409/410 mm, manufactured on existing technology, was laminated 1185 tons of pipe size h according to GOST 8732, and the mandrel diameter 309/310 mm - 865 tons of oil pipes size 325×9 GOST 8732. Both Dorn out of order on the grid razgonnyj cracks. The mandrel diameter 409/410 mm, produced by the new technology, was laminated to the first repoint 1350 tonnes of pipe size 426×9 GOST 8732. On the surface of the mandrel began to appear in the grid razgonnyj cracks. The mandrel was removed from the technological cycle and Peretokin. When the grinding was removed weld heat-resistant wear-resistant layer, and then applied new heat-resistant layer with a thickness of 20.1 mm, taking into account stock for machining. After surfacing of heat resistant isooctanol the layer made of the finishing machining, and the surface of the mandrel was hardened by rolling the roller. Then on the mandrel diameter 409/410 mm after the first reshaping and welding a new heat-resistant layer was laminated 1035 tons of pipe size 426×9 GOST 8732. On the surface of the mandrel began to appear in the grid razgonnyj cracks. The mandrel was removed from the technological cycle and again Peretokin. When the grinding was removed weld heat-resistant wear-resistant layer, applied a new layer with a thickness of 19.8 mm After surfacing wear-resistant heat-resistant layer and the finishing machining surface of the mandrel hardened by rolling the roller. Then the mandrel was laminated 1100 tons. After the third reshaping and welding on this mandrel was still a laminated 1075 tons of pipes. A similar process sequence was produced on the mandrel diameter 309/310. The table shows that the resistance of the mandrel diameter 309/310 mm, manufactured and operated by the new technology, is 3515 tons, that is, the resistance increases 4.06 times, compared with mandrel made on existing technology. Dorn was three pareticheski and naplavki with subsequent machining and finishing (hardening) of the working surface of the roller. After repair domowego castle (welding and milling cheeks) Dorn will be used for further production of pipes. The mandrel diameter 409/410 mm, and is made on the proposed technology, laminated 4560 tons of pipe size 426×9 mm, i.e. its resistance increased to 3.85 times, compared with mandrel made on existing technology. The mandrel can be used for further work after welding and milling of the castle, and the fourth reshaping and welding work surface.

Thus, the mandrel diameter 309/310 mm, manufactured and operated according to existing technology, laminated 865 tonnes of pipe size 325×9 mm (Dorn went out on a grid razgonnyj cracks), and on the mandrel, constructed and operated according to the proposed technology, after three and re-welding of wear-resistant heat-resistant layer, laminated 3515 tons of pipes, i.e., the resistance increases 4.06 times. The mandrel diameter 409/410 mm, manufactured and operated according to existing technology, laminated 1185 tons of pipe size 426×9. Dorn went out on a grid razgonnyj cracks. The mandrel diameter 409/410 mm, manufactured and operated according to the proposed technology, for 3 times and overlaying laminated 4560 tons of pipe size 426×9 mm, i.e. the resistance of the mandrel increased 3.85 times. The mandrel can be used in the work after repair (welding) and milling Dernovoy castles, as well as reshaping and welding on the working surface of the new heat-resistant layer.

The use of the proposed method of manufacture on RNAV piligrimage mills for the production of hot-rolled pipes of large and medium diameter allows it to be used as the basis domowych billets ingots of carbon steel (20) instead of the alloy (HF), significantly increase their resistance, and consequently to reduce the share of costs of technological tools in the cost of pipes.

1. The method of manufacture of mandrels piligrimage mills for the production of hot-rolled pipes of large and medium diameters, including the casting of ingots of steel, getting domowych blanks, heat treatment domowych blanks, machining of dies to finish size with subsequent hardening by rolling the roller, characterized in that the ingots cast from carbon steel, the surface of the ingot is applied by the welding heat-resistant layer and is obtained from the ingot billet mandrel by piligrimages rolling, and in the process of operation after the appearance of the grid razgonnyj cracks produce multiple grinding mandrel to remove the heat-resistant layer, application of new heat-resistant layer by welding, mechanical processing finishing size and hardening of the running roller.

2. The method according to claim 1, characterized in that the thickness of the heat-resistant layer is determined from the expression

Δ=A·μ·(1+D/S·K),

where a is the minimum thickness of the deposited layer after finishing the machining of the mandrel equal to 10 mm;

D is the maximum diameter of the pipes, the car is supported on the mandrel, mm;

S - the minimum wall thickness of pipes, rolled on the mandrel, mm;

μ - drawing ratio during rolling of ingots in the hollow mandrel semi-automatic workpiece;

K - coefficient of 0.02.



 

Same patents:

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

FIELD: metallurgy and mechanical engineering.

SUBSTANCE: the invention is pertaining to the field of metallurgy, in particular, to production of welded pipes for oil, gas- and product pipelines and other analogous designs (containers, pressurized cylinders) working in the difficult geologic, environmental conditions and in presents of aggressive corrosive mediums. The pipe for oil, gas- and product pipelines is made out of a steel smelt using the high-purity or pure charge materials bearing carbon, manganese, silicon, chromium, nickel, vanadium, niobium, titanium, aluminum, calcium, sulfur, phosphorus, nitrogen, copper, antimony, stannous, arsenic and iron and also molybdenum at the following ratio of components (in mass %): carbon - 0.02-0.11, manganese -0.10-1.80, silicon - 0.06-0.60, chromium - 0.005-0.30, nickel - 0.005-1.0, vanadium - 0.01-0.12, niobium - 0.02-0.10, titanium - 0.01-0.04, aluminum - 0.01-0.05, calcium - 0.0005-0.008, sulfur - 0.0005-0.008, phosphorus -0.001-0.012, nitrogen - 0.001-0.012, copper - 0.005-0.25, antimony 0,0001-0,005, stannous 0,0001-0,007, arsenic 0,0001-0,008, molybdenum - 0.001-0.5, iron - the rest. At that thus the total contents of nickel and manganese depends on a concentration of molybdenum and phosphorus in mass % in the following ratio: (Ni + Mn/1 + Mo)P <0.03. The method of production of the indicated pipe includes smelting of steel with the indicated composition, its treatment in a ladle, casting, hot rolling, molding and welding. The hot rolling is conducted by a reversing rolling mill or continuous rolling mills with the following controlled accelerated chilling.

EFFECT: the invention ensures increased efficiency of production of pipes for oil, gas- and product pipelines working in the difficult geologic, environmental conditions in presents of aggressive corrosive mediums.

2 cl, 2 tbl

FIELD: rolled tube production, namely processes for making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters.

SUBSTANCE: method of making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters in range 273-550 mm comprises steps of casting steel ingots; forging cylindrical solid or hollow blanks; subjecting blanks to rough working, to heat treatment and working them for final size; hardening blank surface by means of roller; maintaining mandrels until formation of lattice of thermal erosion cracking. Before heat treatment constant- thickness heat- and wear-resistant layer is welded on outer surface of carbonaceous mandrel blank along 2/3 of its working length of mandrel from its joint part while taking into account allowance for mechanical working. Thickness of said layer is decreased towards end of mandrel by 3-4 times. During process of operation mandrel is reground. Then heat- and wear-resistant constant-thickness layer is welded on outer surface of mandrel along 2/3 of its working length from joint part. Thickness of said layer is decreased towards end of mandrel by 3-4 times. Regrinding and layer surfacing steps are performed multiply. Invention allows to use carbon steel instead of alloyed steel at making mandrels, provides increased by 3.5 - 4 times strength of mandrels.

EFFECT: lowered cost of mandrels and therefore reduced cost of conversion of hot rolled tubes in tube rolling aggregates with pilger mills.

1 tbl

FIELD: metallurgy; hardening of oil grade pipes made from carbon steel and low-alloy steel (Nb, V, Mo and Cr) directly in the course of hot deformation.

SUBSTANCE: proposed method includes preliminary deformation of pipes, holding them in air, heating to 800-870 C for final deformation and accelerated adjustable cooling to 720-760 C performed during repeated hot deformation in compressed-to-solid state at average rate of cooling of 40-60 C/s in center of deformation and 20-30 C/s during inter-deformation intervals.

EFFECT: possibility of obtaining pipes of required geometric parameters in ovality and linearity at enhanced strength, ductility and heat resistance of steel.

1 tbl

FIELD: iron metallurgy, in particular manufacturing of hot-rolled steel and products the same.

SUBSTANCE: method includes matrix steel smelting in steel furnace, containing carbon, manganese, silicium, and iron; tapping into ladle; introducing into bottom zone of ladle mixture for microalloying and deoxidation containing aluminum, calcium, and boron with simultaneous blasting with nitrogen through the bottom jet; and simultaneous complete of mixture introducing and nitrogen blasting; steel casting, and steel ingot producing. Ingot contains (mass %) carbon 0.12-0.42; silicium 0.17-1.10; manganese 0.5-1.8; calcium 0.001-0.02; aluminum 0.02-0.05; aluminum nitride 0.01-0.0.04; boron 0.0001-0.0005; boron nitride 0.001-0.005; nitrogen 0.005-0.012; and balance: iron and inevitable impurities. Ingot is taken out, hot rolled up to desired product dimensions and thermal hardened. Optionally (for example to produce additional rolled product characteristic such as improved tensile strength, ultimate strength, wearing capacity) steel may be additionally doped with chromium, nickel, copper, molybdenum and/or vanadium. Steel of present invention is useful for production of oil pump bars of 15-40 mm in diameter and up to 8.5 m in length.

EFFECT: steel with improved mechanical characteristics.

11 cl, 2 tbl, 1 ex

The invention relates to the processing of metals by pressure and can be used to obtain billets for multi-stage cold rolling of tubular structural elements of the active zones of nuclear reactors

The invention relates to the manufacture of high strength, resistant to sulfide cracking, cold-resistant and corrosion-resistant oil country tubular goods from carbon and alloyed strong carbidopa elements (Cr, Mo, V, Nb, etc.) steels

The invention relates to a method of manufacturing gun barrels and can be used for manufacturing of all types of firearms

The invention relates to pipe manufacture and can be used in the manufacture of large diameter pipe welding method

The invention relates to the metallurgy of steel and can be used in the manufacture of pipeline cold pipes, resistant to destruction in a wet hydrogen sulfide-containing environments

FIELD: manufacture of plungers of long-stroke telescopic hydraulic cylinders in automobile making industry, agricultural machine engineering and road building.

SUBSTANCE: method comprises steps of working inner and outer surfaces of parts, trimming ends and chamfering; working blank of part in rolling mill by plastic deforming simultaneously on inner and outer surfaces by cold rolling for producing mirror surface; then trimming ends of part.

EFFECT: simplified process of making plungers, reduced metal losses, enhanced quality of surface and improved strength characteristics of plungers.

1 ex

FIELD: rolled tube production, namely processes for making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters.

SUBSTANCE: method of making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters in range 273-550 mm comprises steps of casting steel ingots; forging cylindrical solid or hollow blanks; subjecting blanks to rough working, to heat treatment and working them for final size; hardening blank surface by means of roller; maintaining mandrels until formation of lattice of thermal erosion cracking. Before heat treatment constant- thickness heat- and wear-resistant layer is welded on outer surface of carbonaceous mandrel blank along 2/3 of its working length of mandrel from its joint part while taking into account allowance for mechanical working. Thickness of said layer is decreased towards end of mandrel by 3-4 times. During process of operation mandrel is reground. Then heat- and wear-resistant constant-thickness layer is welded on outer surface of mandrel along 2/3 of its working length from joint part. Thickness of said layer is decreased towards end of mandrel by 3-4 times. Regrinding and layer surfacing steps are performed multiply. Invention allows to use carbon steel instead of alloyed steel at making mandrels, provides increased by 3.5 - 4 times strength of mandrels.

EFFECT: lowered cost of mandrels and therefore reduced cost of conversion of hot rolled tubes in tube rolling aggregates with pilger mills.

1 tbl

The invention relates to metal forming, manufacturing conal fingers tie rods and ball joints front suspension cars

The invention relates to the processing of metals by pressure and can be used for making the step axles and shafts transverse rolling

The invention relates to a press-forging production and can be used for three-dimensional stamping parts variable diameter

The invention relates to the processing of metals by pressure, and is intended for receiving the shaft and the axes of the stepped profile using the method of cross-wedge rolling

The invention relates to the processing of metals by pressure and can be used in the manufacture of stepped parts

The invention relates to the processing of metals by pressure, namely the mills cross-wedge rolling speed of the rollers of the piece blanks

FIELD: rolled tube production, namely processes for making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters.

SUBSTANCE: method of making mandrels of pilger mills for rolling of hot rolled tubes with mean and large diameters in range 273-550 mm comprises steps of casting steel ingots; forging cylindrical solid or hollow blanks; subjecting blanks to rough working, to heat treatment and working them for final size; hardening blank surface by means of roller; maintaining mandrels until formation of lattice of thermal erosion cracking. Before heat treatment constant- thickness heat- and wear-resistant layer is welded on outer surface of carbonaceous mandrel blank along 2/3 of its working length of mandrel from its joint part while taking into account allowance for mechanical working. Thickness of said layer is decreased towards end of mandrel by 3-4 times. During process of operation mandrel is reground. Then heat- and wear-resistant constant-thickness layer is welded on outer surface of mandrel along 2/3 of its working length from joint part. Thickness of said layer is decreased towards end of mandrel by 3-4 times. Regrinding and layer surfacing steps are performed multiply. Invention allows to use carbon steel instead of alloyed steel at making mandrels, provides increased by 3.5 - 4 times strength of mandrels.

EFFECT: lowered cost of mandrels and therefore reduced cost of conversion of hot rolled tubes in tube rolling aggregates with pilger mills.

1 tbl

Up!