Method of production and operation of pilger mill mandrels

FIELD: pipe rolling.

SUBSTANCE: applicable for production and operation of pilger mill mandrels. Cakes are cast from the carboniferous-grade steel. The heat-resistant wear-proof coating is applied to the cakes by weld depositing. Mandrel semifinished items are produced from the cakes by pilger mill rolling followed by thermal treatment of the mandrel semifinished items. Then mechanical treatment is performed to achieve the finish size, followed by strengthening by wheel rolling. In the process of mandrel operation upon emerging of the crevice array, the mandrel regrinding is performed multiple times until full removal of the heat-resistant wear-proof coating; then the new heat-resistant wear-proof coating is applied by weld depositing, followed by mechanical treatment to achieve the finish size, and strengthening by wheel rolling. The heat-resistant wear-proof coating of constant thickness is applied at the bottom end of the cake while producing the mandrels, up to two-thirds of the cake's height. The thickness of the mentioned coating layer is gradually reduced by 2-3 times toward the pipe end of the cake. After the mandrel regrinding, the heat-resistant wear-proof coating is applied to two-thirds of their length from the mandrel head to the front conic part of the mandrel while gradually reducing the layer thickness by 2-3 times. The heat-resistant wear-proof coating layer thickness on the cakes Δ and on the mandrel semifinished items Δ1 is defined from the given formulae.

EFFECT: mandrel durability and material saving.

2 cl, 1 tbl

 

The invention relates to pipe production, and in particular to a method of manufacturing and the operation of the processing 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 and operation of the mandrels piligrimage mills for rolling hot-rolled pipes of large and medium diameters, including the casting of ingots of steel grade LED1 (50HN) with the 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 of the surface of the rolling roller or grinding and exploitation to education grid razgonnyj cracks, waves or longitudinal cracks (Faganello and other Hot rolling pipe. 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 "H is PZ").

The disadvantage of this method is that Dorn fail, for "the 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 pipes with a diameter of 325 mm 426 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 1500-3500 mm from the castle part is heated to 650°C. the Highest temperature of the mandrel is in the area from 2000 mm 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 cracks with a depth of 1/3 is about 3/4 of the radius of the mandrels are a consequence of the low values of plastic properties and impact toughness of the steel at cyclic temperatures.

There is also known a method of manufacture and operation of the mandrels piligrimage mills 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 the topic 23-V-13-81 /19-72/ P2 - app "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 Acl-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). Those who lostalone damage to the 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.

There is also known a method of manufacture of mandrels (pots) 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 to, and annealing of workpieces (RF Patent No. 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 the same disadvantages. The resistance of the mandrels has increased the 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 closest technical solution is the method of manufacture and operation of the mandrels piligrimage mills for rolling of pipes of large and medium diameters, including the casting of ingots of carbon steel, coating the surface of the ingot by welding heat-resistant layer and the receipt of the ingot billet mandrel by piligrimages rolling, and in the process of operation after the appearance of the grid razgonnyj cracks frequent resharpening of the 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=Aμ(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; μ - drawing ratio during rolling of ingots in the hollow mandrel semi-automatic billet; 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; K - coefficient of 0.02 (Patent RF №2256708 from 20.07.2005,, bull. No. 20).

However, the known method has the defects in the TCA. The resistance of the mandrels, as compared to the existing, increased on average ≈ 4 times. For manufacturing domowych billets of steel 20 with repeated application of the heat-resistant layer by deposition, with subsequent machining and burnishing roller is used honey hardfacing wire (type SVHN). The length of the mandrel consists of a length of the locking parts (the head pipes) and a working part, two thirds of which is directly working on which is the main deformation of the sleeve into the tube and which, when deformation and contact with hot liner-pipe is heated to a temperature of 650°C and above. One third of the mandrel (guide portion) is required for priming the cartridge case at the beginning of rolling, which is not experiencing long-term stress and has a temperature not exceeding 300°C. At this site Dorn "wave" (flute) and asgarnia cracks are not formed, so this section of the mandrel can be produced and operated with a smaller thickness of the heat-resistant layer, i.e. to save expensive surfacing wire.

The objective of the proposed method of manufacture and operation of the mandrels piligrimage mills is the preservation of the existing level of resistance of dies for rolling hot-rolled pipes of large and medium diameter with simultaneous saving of expensive surfacing is Revoluci SVHG, reducing their cost savings hardfacing wire, and therefore, decrease the cost of technological tools in the cost of pipes.

The technical result is achieved by the known method of manufacture and operation of the mandrels piligrimage mills for the production of hot-rolled pipes of large and medium diameters, including the casting of ingots of carbon steel grades, coating the surface of the ingots by welding heat-resistant layer, obtaining ingots of domowych blanks by piligrimages rolling, heat treatment domowych blanks, machining to finish size with subsequent hardening by rolling the roller and repeatedly carried out during operation of the mandrels after the appearance of the grid razgonnyj cracks the grinding mandrels to remove the heat-resistant layer, application of new heat-resistant layer by welding, heat treatment and mechanical processing to finish size with subsequent hardening by rolling the roller, in the manufacture of mandrels put heat-resistant wear-resistant layer of constant thickness with the bottom end of the ingot by two-thirds of its height, when the thickness of the mentioned layer gradually reduce 2-3 times to shrink part of the ingot, and after each regrinding Dorn put new th is resistant wear-resistant layer of constant thickness at two-thirds the length of the mandrel from the head pipes with a subsequent gradual decrease in thickness 2-3 times to the front conical section of the mandrel, and a constant thickness of the heat-resistant layer on the ingots Δ and domowych blanks after regrinding Δ1accept terms and conditions maximum pressure of the metal in the deformation zone and determine the expression Δ=Aμ(1+D/S·), Δ1=Δ(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 equal to 0,02-0,025, and large values of the ratio correspond to the mandrels for rolling tubes with a large ratio D/S.

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, from outstay cooling during deformation, extreme temperature variations of the working surface of the mandrels during one cycle of operation (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 fair size with subsequent hardening by rolling the 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, produce Termal is abode, mechanical processing with subsequent hardening roller.

Thus, the mandrel operate 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 and operation of the mandrels piligrimage mills for the production of hot-rolled pipes of large and medium diameter differs from the known fact that in the manufacture of mandrels put heat-resistant wear-resistant layer of constant thickness with the bottom end of the ingot by two-thirds of its height, when the thickness of the mentioned layer gradually reduce 2-3 times to shrink part of the ingot, and after each regrinding Dorn put a new heat-resistant wear-resistant layer of constant thickness at two-thirds the length of the mandrel from the head pipes with a subsequent gradual decrease in thickness 2-3 times to the front conical section of the mandrel, the constant thickness of the heat-resistant layer on the ingots Δ and domowych blanks after regrinding Δ1accept terms and conditions maximum pressure of the metal in the deformation zone and determine the expression Δ=Aμ(1+D/S·), Δ1=And(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 - maximum diametral, 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 equal to 0,02-0,025, and large values of the ratio correspond to the mandrels for rolling tubes with a large ratio of D/S. Thus, these differences allow us to conclude that the criterion of "inventive step".

Comparison of the proposed method 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 corresponds to paternopoli "inventive step".

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 mm 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, made of solid forged steel HF and operated by an existing method, is 1185 tons of pipe size 426×9 mm, and the diameter mandrels 309/310 mm - 865 tonnes of pipe size 325#x000D7; 9 mm mandrel in patent No. 2256708 and a new method was made based on the following technologies: bullion 20 size 420×2000 mm drilled Central hole with a diameter of 150±5.0 mm, and bars of size 520×2100 mm - Central hole with a diameter of 100±5.0 mm, then these ingots way of surfacing was applied heat-resistant wear-resistant layer steel SWAN thickness respectively 60,0 55,0 and mm. patent No. 2256708 heat-resistant wear-resistant layer is deposited on the entire surface of the ingot, and the proposed technology was applied from the bottom end ingot two-thirds of its height, with a subsequent gradual decrease three times to shrink parts, i.e. the thickness of the deposited layer was decreased with 60,0 mm to 20 mm and with 55,0 up to 18 mm, the Ingot was heated in the reheating furnaces to a temperature 1270-1280°C. the Ingots the size of 630×100×2100 mm was stitched in the piercing mill in sleeves size 600×215×2600 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 540×130×2000 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 is TKE on finishing size respectively 409/410 and 309/310 mm with subsequent hardening by rolling the roller. On the mandrel steel HF diameter 409/410 mm, manufactured on existing technology, was laminated 1185 tons of pipe size 426×9 mm according to GOST 8732, and the mandrel diameter 309/310 mm - 865 tons of oil pipes size 325×9 mm according to GOST 8732. Both Dorn out of order on the grid razgonnyj cracks. The mandrel diameter 409/410 mm, manufactured under patent No. 2256708, three times and overlaying laminated 4560 tons of pipe size 426×9 mm according to GOST 8732, and the mandrel diameter 309/310 mm - 3615 tons size 325×9 mm When welding bars size 420×150×2000 mm used in this method was spent 1419 kg welding wire steel grade SVHS, and when overlaying the ingot size 520×100×2100 mm - 1637 kg On the proposed method, respectively 1275 and 1523 kg, i.e. in 1.11 and 1.08 times less. On the surface of the mandrel diameter 409/410 mm, made of the proposed technology, after rolling 1265 tons of pipe size 426×9 mm 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. After regrinding the mandrel diameter 409/410 mm had a length of 3000 mm from piligrimages head diameter 390 mm, which gradually increased to the front end up to 405 mm, i.e. the front end of the mandrel for a length of 1500 mm was in the form of a truncated cone, the smaller base of which Rav is about 390 mm, and more (the front end of the mandrel) 405 mm, Then two-thirds the length of the mandrel from the head pipes applied, taking into account an allowance under mechanical treatment, a new heat-resistant layer with a thickness of 20.2 mm, which is due to the gradual reduction of the front conical section of the mandrel was 6.8 mm After surfacing wear-resistant heat-resistant layer produced by thermal treatment and 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 1205 tons of pipe size 426×9 mm according to 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 final stage was cleared of deposited wear-resistant layer, applied a new layer, the maximum thickness of which on the side facing the head pipes was 20.4 mm, and from the front end of 7.0 mm After surfacing wear-resistant heat-resistant layer, heat treatment and clean machining the surface of the mandrel hardened by rolling the roller. Then the mandrel was laminated 1155 tons of pipe size 426×9 mm After the third reshaping and welding on this mandrel was laminated else 955 tonnes of pipe size 426×9 mm. Similar technological sequence of production is odiles and mandrel diameter 309/310 mm. The table shows that the resistance of the mandrel diameter 409/410 mm, manufactured and operated by the new technology, was 4640 tons, i.e., the resistance increased, as compared with a solid mandrel of steel grade HM, 3.92 times, as compared with mandrel made to patent No. 2256708, remained at the same level (increased by 1.75%). Dorn walked three times and welding and subsequent heat treatment, machining and hardening the surface of the roller. After repair domowego castle (welding and milling cheeks) Dorn will be used for further production of pipes. The mandrel diameter 309/310 mm, made of the proposed technology, laminated 3565 tonnes of pipe size 325×9 mm, i.e. its resistance, as compared with a solid mandrels of steel HF increased 4,12 times, as compared with mandrel made to patent No. 2256708 increased by 1.4%. 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 by patent No. 2256708, laminated 3515 tonnes of pipe size 325×9 mm, and on the mandrel, constructed and operated according to the proposed technology, after three and re-welding of wear-resistant heat-resistant layer laminated 3565 tons of pipes, i.e. resistance to the to have increased by 1.4%. The mandrel diameter 409/410 mm, manufactured under patent No. 2256708, laminated 4560 tons of pipe size 426×9 mm, and the mandrel diameter 409/410 mm, manufactured and operated according to the proposed technology, for 3 times and overlaying laminated 4540 tonnes of pipe size 426×9 mm, i.e. the resistance of the mandrel has increased by 1.75%. The mandrel can be used in the work after repair (welding and milling domowych castles and cheeks), as well as reshaping and welding on the working surface of the new heat-resistant layer. When overlaying the ingots the size of 420×150×2000 mm for rolling domowych preparations for the manufacture of mandrels with a diameter of 309/310 mm patent No. 2256708 spent wire steel grade SVHS - 1359 kg, and on the proposed technology 1275 kg Saving wire in the manufacture of the mandrel on the proposed technology was 84 kg When overlaying the ingots the size of 420×150×2000 mm for rolling domowych preparations for the manufacture of mandrels with a diameter of 409/410 mm patent No. 2256708 spent wire steel grade SVHS - 1637 kg, and on the proposed technology 1523 kg Saving wire in the manufacture of the mandrel on the proposed technology was 114 kg each grinding and surfacing domowych blanks saving wire is respectively 42 kg and 57 kg

The use of the proposed method of manufacture of mandrels piligrimage with the ANOVA for the production of hot-rolled pipes of large and medium diameter reduces hardfacing wire steel grade SVHS while maintaining the durability of the mandrels at the current level, therefore, to reduce the share of costs of technological tools in the cost of pipes.

1. The method of manufacture and operation of the mandrels piligrimage mills for the production of hot-rolled pipes of large and medium diameters, including the casting of ingots of carbon steel grades, coating the surface of the ingots by welding heat-resistant layer, obtaining ingots of domowych blanks by piligrimages rolling, heat treatment domowych blanks, machining to finish size with subsequent hardening by rolling the roller and repeatedly carried out during operation of the mandrels after the appearance of the grid razgonnyj cracks the grinding mandrels to remove the heat-resistant layer, application of new heat-resistant layer by welding, heat treatment and machining to finish size with subsequent hardening by rolling the roller, characterized in that in the manufacture of mandrels put heat-resistant wear-resistant layer of constant thickness with the bottom end of the ingot by two-thirds of its height, when the thickness of the mentioned layer gradually reduce 2-3 times to shrink part of the ingot, and after each regrinding Dorn put a new heat-resistant wear-resistant layer of constant thickness on two tre and the length of the mandrel from the head pipes with a subsequent gradual decrease in thickness 2-3 times to the front conical section of the mandrel.

2. The method according to claim 1, characterized in that a constant thickness of the heat-resistant layer on the ingots Δ and domowych blanks after regrinding Δ1accept terms and conditions maximum pressure of the metal in the deformation zone and determine the expression

Δ=Aμ(1+D/S·K),

Δ1=A(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 - factor equal to 0,02-0,025, and large values of the ratio correspond to the mandrels for rolling tubes with a large ratio of D/S.



 

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FIELD: production of rolled tubes, possibly manufacture and operation of drifts of pilger mills.

SUBSTANCE: method comprises steps of casting ingots of carbon steels; applying onto ingot surface by surfacing heat- and wear- resistant layer; making from ingots drift blanks by pilger rolling; performing heat treatment of drift blanks; then performing mechanical working of blank to final size for further strengthening of it due to rolling around by means of roller. During operation of drifts after occurring of net of burnout cracking drifts are subjected to multiple returning till removing heat- and wear-resistant layer. Then new heat and wear resistant layer is applied by surfacing, heat treatment and mechanical working till final size are realized for further strengthening of blank due to rolling around by roller. Heat and wear resistant layer is applied beginning from bottom end of ingot along 2/3 of its height. After returning of drifts heat and wear resistant layer is applied along 2/3 of their length beginning from drift head with further smooth transition along length 100 - 150 mm. Thickness values of heat and wear resistant layer on ingots and on drift blanks are determined according to given expressions.

EFFECT: improved strength of drifts, rational metal consumption.

2 cl, 1 tbl

а

FIELD: roller type centering apparatuses for enlarging possibilities of blank centering in tube rolling mill.

SUBSTANCE: centering apparatus includes housing; jointly mounted in housing rocking two-arm lever with upper centering roller; jointly coupled one to other through timing tie rod two-arm and three-arm levers with lower centering rollers; drive unit for closing and opening lever arms; screw type limiter of roller positions. Effective adjustment of equipment to desired size, extraction of pierced billet from upward and from lateral side are provided due to improved design of centering apparatus. The last has hydraulic cylinder whose body is mounted on arm of rocking two-arm lever with upper centering roller and whose rod is jointly coupled with three-arm lever carrying lower centering roller. Screw type limiter of centering apparatus is provided with electromechanical drive and it is mounted in housing with possibility of engaging with stop placed on timing tie rod.

EFFECT: improved design of centering apparatus, enlarged possibilities of blank centering.

3 dwg

FIELD: rolled stock production, namely tube rolling mills for manufacturing seamless tubes, particularly arresting and regulating mechanism of rear table of helical rolling mill for tube producing.

SUBSTANCE: carriage with arresting head and with lock is mounted in housing. Said carriage supports mandrel stem with mandrel, screw mechanism for moving carriage and hydraulic cylinders for moving stem with mandrel during rolling process. Hydraulic cylinders are mounted in parallel relative to carriage at different sides from it coaxially to screws axes of mechanism for moving carriage. Rods of hydraulic cylinders through spherical step bearing assemblies are joined to carriage. Spherical supports coupled to spherical step bearing assemblies of screw mechanism for moving carriage are mounted on bodies of hydraulic cylinders.

EFFECT: improved operational reliability, increased useful life period of arresting and regulating mechanism for moving stem with mandrel during rolling process and of the whole equipment.

1 dwg

FIELD: rolled tube production, namely working tool of piercing mills, possibly for making conversion tubes of large and mean diameters from titanium base alloys in tube rolling plants with pilger mills, namely producing tube blanks for making bottles or other tube products.

SUBSTANCE: plug of piercing mill for piercing ingots and billets of titanium base alloys includes nose part in the form of cone, working part for deformation of sleeve wall, cylindrical band for forming inner diameter and for calibrating sleeve wall, inverse cone in the form of cylindrical stem with length L r.c. = (0.2 -).5) Lm and with diameter D r.c. = [Dm -(4 -5)] mm, where Lm - total length of plug, mm; Dm - diameter of plug, mm. Invention prevents partially or completely occurring of annular mushroom-shaped swellings on inner surface of sleeves.

EFFECT: shortened time period, improved condition of guiding plug to sleeve, elevated temperature of starting process of rolling sleeves to conversion tubes, lowered consumption of titanium base alloy, reduced cost of conversion of ingots or blanks of titanium base alloys to tube blanks.

2 dwg, 1 tbl

FIELD: rolled tube production, namely designs of manufacturing tools such as mandrels for pilger rolling of hot rolled tubes.

SUBSTANCE: mandrel for pilger rolling of tubes includes locking, working and guiding portions and it is made of heat- and wear-resistant steel with linearly increased forging reduction from guiding to locking portion. Guiding portion consisting 0.3 - 0.35 of total length of mandrel is made of steel with less heat resistance subjected to the same heat treatment and having almost the same linear expansion factor as steel of other portions.

EFFECT: low cost of mandrels for pilger rolling of large- and mean-diameter hot rolled tubes due to making guiding portion of mandrel of steel with less heat resistance and less cost, lowered cost of conversion process of hot rolled tubes in tube rolling aggregates with pilger mills.

3 cl, 1 dwg

FIELD: plastic metal working at making tubes, possibly piercing and expanding tubes of refractory metals, namely apparatuses for centering mandrel rod and changing mandrel of vacuum mill for screw rolling of tubes.

SUBSTANCE: apparatus for centering mandrel rod and changing mandrel includes stationary centering device having movable centering sleeve in the form of cylinder with tip at one side and member for joining with drive unit arranged outside vacuum chamber at other side; additional vacuum chamber designed for inspecting and changing mandrel and communicated with main chamber of mill by means of flange and vacuum seal. Additional vacuum chamber has vacuum seal unit in other flange for extending rod outside chamber and supporting-regulating mechanism of mandrel rod with drive unit. Mandrel rod includes working, basic and supporting-drive portions and in addition it includes intermediate portion whose diameter is less that of working portion. Movable centering sleeve is elongated, its back end extends outside additional vacuum chamber through vacuum seal unit. Vacuum seal unit of basic portion of mandrel rod is arranged in back end of said sleeve having inner cavity in the form of cylindrical parts with diameters stepwise reduced from front end to back end and exceeding diameters of respective portions of mandrel rod. Hollow inserts are mounted between sleeve and mandrel rod with possibility of their motion along respective inner portions of sleeve and mandrel rod. Said inserts are provided with members of anti-friction materials.

EFFECT: enlarged assortment of elongated tubes made in vacuum condition, enhanced operational reliability of apparatus, improved efficiency of mill.

2 dwg

FIELD: metallurgy, namely casting electroslag refining ingots for making large-size mandrels used for producing seamless hot rolled large- and mean-diameter tubes in tube rolling plants with pilger mills.

SUBSTANCE: method for making mandrel including lock, working and guiding portions comprises steps of casting electroslag refining ingot of heat- and wear-resistant steel; forging ingot to cylindrical forged billet with linear increase of forging reduction ratio from guiding portion to lock one; rough working of forged billet to mandrel blank; heat treatment of mandrel blank and finish working of it to mandrel. Bottom part of ingot is cast of steel with high resistance against friction and against increased percussion pressure. Mean part of ingot is cast of heat- and wear-resistant steel. Shrinkage head part of ingot is cast of steel with less heat resistance. Bottom part is cast in zone of 0.1 - 0.15 of total height of ingot; mean part is cast in zone of 0.5 - 0.6 of total height of ingot and shrinkage part is cast in zone of 0.30 -0.40 of total height of ingot. Lock portion of mandrel is made of bottom part of ingot; working portion - from mean part of ingot and guiding portion of mandrel is made of shrinkage part of ingot. In order to cast electroslag refining ingot, electrodes of steels having almost the same linear expansion factors are used; in order to make bottom and mean parts of ingot electrodes of steels subjected to the same heat treatment are used. Invention prevents crumpling of side faces, surfacing them with use of austenite electrodes and additional milling and therefore provides lowered cost of conversion of hot rolled tubes in tube rolling aggregates with pilger mills.

EFFECT: reduced cost of mandrels due to making guiding portion of them of steel having less heat resistance and less cost, improved strength of lock portion of mandrel due to casting bottom portion of ingot of steel having high resistance against friction and increased percussion pressure.

6 cl, 1 dwg

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

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: rolled tube production, namely method for making pilger mill mandrels from heat resistant steel for rolling hot rolled tubes.

SUBSTANCE: method for making mandrels used for rolling hot rolled tubes with large and mean diameters in range 273-550mm comprises steps of casting ingots of hear resistant steel; forging cylindrical solid or hollow blanks, roughly working of them, performing heat treatment and finishing mandrels at forming conicity 1 - 2 mm on length of their working portion while taking into account designed linear expansion coefficient during rolling process; determining diameter size by means of expression δ = dn - Δ/1 + α·t. One portion of mandrel from lock along length of half of working portion of mandrel is in the form of cone with diameters of cone bases determined form given expression and second portion is in the form of cylinder or truncated cone whose diameters are determined according to next expression

EFFECT: lowered lengthwise thickness difference of tubes.

3 cl, 1 dwg, 1 tbl

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