RU2522508C1 - Production of seamless hot-rolled pipes at pru with pilger mill - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: proposed method comprises heating the ingots to ductility temperature and piercing them at helical rolling mill to sleeves with different rolling-out µ_pr, µ_pr1 and µ_pr2 over the length. Ingots are pierced at helical rolling mill to sleeves shaped to two hollow connected truncated cones. One of the latter features length equal to (0.10-0.15) of sleeve length, its smaller base being located at front end along sleeve piercing. Second cone features length equal to (0.85-0.9) of sleeve length, its smaller base being located at rear end along sleeve piercing. Sleeves of i^th size are rolled at Pilger mill to pipes of j^th size at constant amount of advance m_ij, steady rolling and rolling-outs µ_pg1ij, µ_pg2ij, and µ_pg3ij, respectively, at seeding, steady rolling and end of rolling - at withdrawing of Pilger heads from the sleeve conical ends. Pipe lengths are cut to pipe arms, process wastes, that is Pilger heads, and seed ends are cut off by hot-cutting saw.

EFFECT: lower metal input, higher precision, higher efficiency, ruled out sleeve rear end collapse.

3 cl, 1 tbl

Description

The invention relates to pipe production, and in particular to a method for the production of seamless hot-rolled pipes, and can be used in the production of seamless hot-rolled pipes in pipe-rolling plants with pilgrim mills incorporating cross-helical rolling mills.

The tube production is known a method of producing a hot rolled seamless tubes on tube rolling plants with pilger whereby heated to plasticity temperature (1250-1300) ° C billet ingot set in helical rolling mill and is sewn to the sleeve with hood μ _ave, the liner is rolled on piligimovyh mills in pipes with an extract of µ _saws , which depends on the geometric dimensions of the liners and rolled pipes (Danilov F.N., Gleiberg A.Z., Balakin V.G. Hot rolling of pipes. Metallurgizdat, 1962, p. 300-301).

The disadvantage of this method for the production of seamless hot-rolled pipes in tube-rolling plants with pilgrim mills is the relatively high expenditure coefficient of the metal, caused by the formation of technological waste in the form of pilgrim heads and seed ends, which make up the bulk of metal waste in the production of pipes by this method.

In pipe production, there is a known method for the production of seamless hot-rolled pipes in plants with pilgrim mills, which includes heating ingots - billets to ductility temperature, piercing them in a cross-screw rolling mill with different hoods along the length µ _pr and µ _pr1 , where the maximum _draw µ _pr1 falls on the portion of the sleeve forming the pilgrim head (RF Patent No. 2151658, class B21B 19/004, B21B 21/00, bull. No. 18 dated June 27, 2000).

The disadvantage of this method for the production of seamless hot-rolled pipes in tube-rolling plants with pilgrim mills is the reduction in feed rates during the steady-state process, depending on the decrease in the temperature of the sleeves from the beginning to the end of rolling, especially when rolling thin-walled pipes and pipes from hardly deformed steel and alloy grades, and increased drive loads pilgrim mill at a fixed feed rate, and also not specified necessary hoods at the end of rolling, in which there is no crushing of the rear ends liners from dynamic impact during the rolling process, and the optimal size profiles rear ends of the sleeves forming the pilger die, i.e. a decrease in their masses depending on the rolling of sleeves of the i-th size into pipes of the j-th size.

The closest technical solution is a method for the production of seamless hot-rolled pipes in pipe-rolling plants with pilgrim mills, including heating ingots - billets to a plasticity temperature, piercing them in a cross-screw rolling mill into sleeves with different hoods along the length µ _pr , µ _pr1 and, µ _pr2 where the maximum μ _np2 extractor falls on a front portion of the sleeve, reducing hood at the front end of the sleeve to _pr12 μ μ _ave due to dilution of the rolls over the length (015-0,20) L _z defining the seed end to pilger tane, which is determined from the expression _np2 μ = (1,4-1,6) μ _ave, where μ _ave - drawing ratio at the steady piercing mill during the firmware on the central portion of the sleeve equal to (065-0,75) L _g, drawing magnification at the rear end of the sleeve to _direct μ μ _pr1 due to information on the length of the rolls, equal to (010-0,15) L _g pilger forming die, which is determined from the expression μ _pr1 = (1.3-1.5) µ _pr , (RF Patent No. 2261151, class B 21 V 21/00, bull. No. 27 dated September 27, 2005).

The disadvantage of this method for the production of seamless hot-rolled pipes in tube-rolling plants with pilgrim mills, as well as the above analogue, is the reduction in the feed rates of the sleeves to the deformation zone during the steady-state process, depending on the decrease in the temperature of the sleeves from the beginning to the end of rolling and the increase in the load on the drive of the pilgrim mill at a fixed feed rate, as well as the necessary geometric dimensions of the rear ends of the liners are not specified, during the rolling of which on the pilgrim mills t crumpling ends sleeves from dynamic impact during the rolling process, and the optimal size profiles front and rear ends of the sleeves forming the pilger die and the seed ends, i.e. a decrease in their masses depending on the rolling of sleeves of the i-th size into pipes of the j-th size.

The objective of the proposed method is the rolling of pipe lashes with a fixed feed at a steady rolling process from seed to rolling of the pilgrim heads with minimal fluctuations in the loads on the drive of the pilgrim mill, eliminating the crushing of the rear ends of the liners from dynamic impacts during rolling and determining the optimal dimensions of the rear and the front ends of the sleeves forming the pilgrim heads and seed ends, the reduction of their masses depending on the rolling of sleeves of the i-th size into pipes of the j-th size .

, где D - наружный диаметр заднего конца первого полого усеченного конуса - диаметр большего основания первого полого усеченного конуса, мм; d - наружный диаметр переднего конца конусной гильзы - диаметр меньшего основания первого полого усеченного конуса, мм и последующего увеличения вытяжек от µ_пр до µ_пр2, за счет плавного сведения рабочих валков относительно оси прошивки, от большего основания второго усеченного конуса к меньшему основанию на величину l₁, значение которой определяют из выражения $$l=\frac{D-d_2}{2}$$

, где d₁ - наружный диаметр заднего конца конусной совмещенной гильзы - диаметр меньшего основания второго полого усеченного конуса, мм, значения вытяжек µ_пр1 и µ_пр2 определяют из выражений µ_пр1=(1,20-1,25) µ_пр, µ_пр2=(1,20-1,30) µ_пр, большие значения которых относятся к слиткам-заготовкам большего диаметра, прокатку гильз i-го размера на пилигримовых станах в трубы j-го размера при установившемся процесс производят с постоянной величиной подачи m_ij и с переменной вытяжкой µ_пгjj, из передних концов гильз формируют затравки, а из задних - пилигимовые головки, прокатку - обкатку пилигримовых головок из конусных гильз i-го размера при прокатке труб j-го размера производят с плавным снижением величин подач m_ij до 0,75 m_ij.The technical result is achieved by the fact that in the known method for the production of seamless hot-rolled pipes in pipe-rolling plants with pilgrim mills, which includes heating ingots to a plastic temperature, piercing them in a cross-helical rolling mill in sleeves with different hoods along the length µ_etc, µ_pr1, and µ_pr2whose front ends are of a length equal to (0.15-0.2) of the length of the sleeve, have the shape of a truncated cone with a smaller base on the front ends, the middle parts at a length equal to (0.65-0.75) of the length of the sleeve have the shape hollow cylinder, and the rear ends at a length equal to (0.1-0.15) of the liner length, the shape of a truncated cone with a smaller base at the rear ends of the liners, rolling the ith-size liners on a pilgrim mill to J-size pipes with a constant feed rate for steady rolling process and hoods µ_pr1ij, µ_pr2ij and µ_pr3ij, accordingly, when the seed, the steady-state process and the end of the rolling - when removing the pilgrim heads from the conical parts of the sleeves, cutting the lashes into pipes - cutting and removal of technological waste - the pilgrim heads and seed ends with a hot cutting saw, ingots - billets in the mill transversely - screw the rolling is stitched into sleeves having the form of two hollow aligned cones, one with a length equal to (0.10-0.15) of the sleeve length has a truncated cone shape whose smaller base is on the front end along the sleeve piercing, and the second length length equal to (0.85-0.9) the length of the sleeve, the smaller base of which at the rear end during the flashing of the shells, the ingots-blanks are flashed into the conical combined hollow shells by reducing the stretch from µ_pr1up to µ_etc, due to the smooth dilution of the work rolls relative to the axis of the firmware, from the beginning of the firmware — the smaller base of the first truncated cone to the larger base by the value l, the value of which is determined from the expression $$l_{\mathrm{one}}=\frac{D-d_{\mathrm{one}}}{2}$$

where D is the outer diameter of the rear end of the first hollow truncated cone - the diameter of the larger base of the first hollow truncated cone, mm; d is the outer diameter of the front end of the conical sleeve is the diameter of the smaller base of the first hollow truncated cone, mm and the subsequent increase in hoods from µ_etc to µ_pr2due to the smooth reduction of the work rolls relative to the axis of the firmware, from the larger base of the second truncated cone to the smaller base by l_onewhose value is determined from the expression $$l=\frac{D-d_2}{2}$$

where d_one - the outer diameter of the rear end of the conical combined sleeve - the diameter of the smaller base of the second hollow truncated cone, mm, hood values µ_pr1 and µ_pr2 determined from the expressions µ_pr1= (1.20-1.25) µ_etc, µ_pr2= (1.20-1.30) µ_etc, large values of which relate to ingots-blanks of larger diameter, rolling of shells of the i-th size on pilgrim mills into pipes of the j-th size with a steady process is carried out with a constant feed rate m_ij and with variable hood µ_pgjj, seeds are formed from the front ends of the sleeves, and piligim heads are formed from the rear ends, rolling - the pilgrim heads are rolled from i-size conical sleeves when rolling j-size pipes with a smooth reduction in the feed rates m_ij up to 0.75 m_ij.

, где D - наружный диаметр заднего конца первого полого усеченного конуса - диаметр большего основания первого полого усеченного конуса, мм; d - наружный диаметр переднего конца конусной гильзы - диаметр меньшего основания первого полого усеченного конуса, мм и последующего увеличения вытяжек от µ_пр до µ_пр2, за счет плавного сведения рабочих валков относительно оси прошивки, от большего основания второго усеченного конуса к меньшему основанию на величину l₁, значение которой определяют из выражения $$l_1=\frac{D-d_1}{2}$$

, где d₁ - наружный диаметр заднего конца конусной совмещенной гильзы - диаметр меньшего основания второго полого усеченного конуса, мм, значения вытяжек µ_пр1 и µ_пр2 определяют из выражений µ_пр1=(1,20-1,25) µ_пр, µ_пр2=(1,20-1,30)µ_пр, большие значения которых относятся к слиткам-заготовкам большего диаметра, прокатку гильз i-го размера на пилигримовых станах в трубы j-го размера при установившемся процесс производят с постоянной величиной подачи m_ij и с переменной вытяжкой µ_пгiJ, из передних концов гильз формируют затравки, а из задних - пилигримовые головки, прокатку - обкатку пилигримовых головок из конусных гильз i-го размера при прокатке труб j-го размера производят с плавным снижением величин подач m_ij до 0,75 m_ij. Таким образом, эти отличия позволяют сделать вывод о соответствии критерию "изобретательский уровень".Comparative analysis with the prototype shows that the inventive method for the production of seamless hot-rolled pipes in tube-rolling plants with pilgrim mills differs in that the ingots - billets in the cross-helical rolling mill are stitched into sleeves having the form of two hollow aligned cones, one with a length equal to (0.10 -0.15) the length of the sleeve, in the form of a truncated cone, the smaller base of which at the front end in the course of flashing the sleeves, and a second length equal to (0.85-0.9) the length of the sleeve, the smaller base of which at the rear end in the direction of shivki sleeves, firmware ingots, blanks in the cone aligned hollow shells produced by reducing the drawing of μ _pr1 to μ _ave, by gradually breeding work rolls relative EEPROM axis from the beginning EEPROM - the smaller base of the first truncated cone to a larger base on the value of l, value which is determined from the expression $$l=\frac{D-d}{2}$$

where D is the outer diameter of the rear end of the first hollow truncated cone - the diameter of the larger base of the first hollow truncated cone, mm; d - the external diameter of the front end of the taper sleeve - the diameter of the smaller base of the first hollow frustoconical mm and a subsequent increase in extracts from μ _ave to μ _np2, by gradually details of the work rolls relative EEPROM axis from the greater base of the second truncated cone to a smaller base by an amount l ₁ , the value of which is determined from the expression $$l_{\mathrm{one}}=\frac{D-d_{\mathrm{one}}}{2}$$

where d ₁ is the outer diameter of the rear end of the conical aligned sleeve - the diameter of the smaller base of the second hollow truncated cone, mm, the values of hoods µ _pr1 and µ _{pr2 are} determined from the expressions µ _pr1 = (1.20-1.25) µ _pr , µ _pr2 = (1.20-1.30) µ _pr , large values of which refer to ingots-blanks of larger diameter, rolling of shells of the i-th size on pilgrim mills into pipes of the j-th size with the steady-state process is carried out with a constant feed value m _ij and with a variable hood µ _ПГiJ , seeds are formed from the front ends of the sleeves, and pilgrim g from the rear ends shafts, rolling - rolling in of pilgrim heads from cone sleeves of the i-th size when rolling pipes of the j-th size is carried out with a smooth decrease in the feed values m _ij to 0.75 m _ij . Thus, these differences allow us to conclude that the criterion of "inventive step" is met.

Comparison of the proposed method not only with the prototype, but also with other technical solutions in the art did not allow them to identify signs that distinguish the claimed method from the prototype, which corresponds to the patentability "inventive step".

, где D - наружный диаметр заднего конца первого полого усеченного конуса - диаметр большего основания первого полого усеченного конуса, мм; d - наружный диаметр переднего конца конусной гильзы - диаметр меньшего основания первого полого усеченного конуса, мм и последующего увеличения вытяжек от µ_пр до µ_пр2, за счет плавного сведения рабочих валков относительно оси прошивки, от большего основания второго усеченного конуса к меньшему основанию на величину l₁, значение которой определяют из выражения $$l=\frac{D-d}{2}$$

, где d₁ - наружный диаметр заднего конца конусной совмещенной гильзы - диаметр меньшего основания второго полого усеченного конуса, мм, значения вытяжек µ_пр1 и µ_пр2 определяют из выражений µ_пр1=(1,20-1,25) µ_пр, µ_пр2=(1,20-1,30)µ_пр, большие значения которых относятся к слиткам-заготовкам большего диаметра, прокатку гильз i-го размера на пилигримовых станах в трубы j-го размера при установившемся процесс производят с постоянной величиной подачи m_ij и с переменной вытяжкой µ_пгij, из передних концов гильз формируют затравки, а из задних - пилигримовые головки, прокатку - обкатку пилигримовых головок из конусных гильз i-го размера при прокатке труб j-го размера производят с плавным снижением величин подач m_ij до 0,75 m_ij.The proposed method for the production of seamless hot-rolled pipes in pipe-rolling plants with pilgrim mills is that ingots - billets in a cross-helical rolling mill are sewn into sleeves having the form of two hollow aligned cones, one of a length equal to (0.10-0.15) the length of the sleeve, in the form of a truncated cone, the smaller base of which at the front end in the course of flashing the sleeves, and the second length equal to (0.85-0.9) the length of the sleeve, the smaller base of which at the rear end in the course of flashing the sleeves, piercing ingots in to usnye combinations hollow sleeve is manufactured by drawing reduction of μ to μ _{ave np2} due to dilution soft work rolls relative to the axis of the firmware from the beginning EEPROM - the smaller base of the first truncated cone to a larger base on the value of l, which value is determined from the expression $$l_{\mathrm{one}}=\frac{D-d_{\mathrm{one}}}{2}$$

where D is the outer diameter of the rear end of the first hollow truncated cone - the diameter of the larger base of the first hollow truncated cone, mm; d - the external diameter of the front end of the taper sleeve - the diameter of the smaller base of the first hollow frustoconical mm and a subsequent increase in extracts from μ _ave to μ _np2, by gradually details of the work rolls relative EEPROM axis from the greater base of the second truncated cone to a smaller base by an amount l ₁ , the value of which is determined from the expression $$l=\frac{D-d}{2}$$

where d ₁ is the outer diameter of the rear end of the conical aligned sleeve - the diameter of the smaller base of the second hollow truncated cone, mm, the values of hoods µ _pr1 and µ _{pr2 are} determined from the expressions µ _pr1 = (1.20-1.25) µ _pr , µ _pr2 = (1.20-1.30) µ _pr , large values of which refer to ingots-blanks of larger diameter, rolling of shells of the i-th size on pilgrim mills into pipes of the j-th size with the steady-state process is carried out with a constant feed value m _ij and variable hood μ _pgij, from the front end of the sleeve forming the seed, and the rear - pilger g dexterous, rolling - pilger run-conical heads of the liners i-th size during rolling pipes j-th size produced with a smooth decrease in the supply amount of up to 0.75 m _ij m _ij.

Determination of theoretically necessary hoods along the length of sleeves when piercing in a cross-helical rolling mill will allow them to be rolled on pilgrim mills into pipes with fixed feed rates, with minimal fluctuations in the loads on the pilgrim mill drives, to reduce the mass of piligim heads and seed ends, and to exclude deformation (crushing ) the rear ends of the sleeves when rolling thin-walled pipes (180-220 feed-strokes of the feeding apparatus).

The method was tested on a pipe-rolling installation with pilgrim mills of 8-16 "OAO" ChTPZ "when rolling pipes of size 377 × 9 and 426 × 10 mm from ingots with a diameter of 15" and 16 "according to the existing one, according to the RF patent No. 2261151 and according to the proposed technologies. Data for piercing ingots with a diameter of 15 and 16 "in a cross-rolling mill, rolling pipes of 377 × 9 and 426 × 10 mm in size on TPU 8-16" with pilgrim mills and delivery of pipes rolled according to existing and proposed technologies, are shown in table 1 .

The firmware process was carried out in the following ways. When rolling pipes with a size of 377 × 9 mm from ingots of 555/505 × 1700 mm according to the existing technology, cylindrical sleeves of 540 × Hv. 390 × 3330 mm in size with a constant drawing µ = 1.95 were obtained on a cross-screw mill. According to the patent No. 2261151, sleeves of 540 × Hvn. 390 × 3480 mm in size were obtained, which had an outer diameter of 490 and 500 mm from the front and rear ends, respectively, at a length of 600 and 500 mm, i.e. the liner wall thickness at the seed end was 50 mm, and under the pilgrim head was 55 mm. Over a length of 2380 mm, the liners had an outer diameter of 540 mm. The hood at the front end of the sleeves gradually decreased from µ = 2.93 to µ = 1.95, and at the rear end it gradually increased from µ = 1.95 to jx = 2.78. According to the proposed technology, sleeves with a size of 510-540-520hvn. 390 × 3600 mm (claims 1 and 2 of the claims) were obtained due to the smooth cultivation of the work rolls of the cross-screw firmware mill at l = 15 mm from the start of the firmware at a length of 420 mm front ends sleeves (seed ends), and then smoothly reducing the work rolls to the end of the firmware by L = 10 mm. The values of extracts µ _pr1 and µ _{pr2 were} determined according to (paragraph 3 of the claims). At the beginning of the firmware, the hood µ _pr1 = 2.53 gradually decreased to µ _pr = 1.95, and then gradually increased to µ _pr2 = 2.34. Hoods µ _pr1 and µ _pr2 cannot be increased uncontrollably, because the length of the sleeve increases with increasing µ _pr1 , and µ _pr2 . It is not advisable to roll a sleeve longer than 3600 mm on an existing pilgrim mill, because front - seed ends extend beyond the line of the centers of the rolls, which leads to their crushing, i.e. to increase the expenditure coefficient of the metal. Rolling pipes of this size from sleeves with a wall thickness at the rear end of less than 60 mm leads to crushing of the rear ends and, consequently, to an increase in the mass of pilgrim heads. According to the proposed method, the rolling of pipes on a pilgrim mill was performed according to (claims 4 and 5 of the claims). After rolling, technological waste — pilgrim heads and seed ends — was removed from all pipes from the hot cutting saw. The average mass of the seed ends of the pipes was, respectively, 41.5, 28.6 and 28.8 kg. The average weight of the pilgrim heads was, respectively, 245, 205 and 183 kg. When rolling sleeves with conical ends under the seed, a decrease in the mass of the grinding ends was obtained by 12.9 and 12.7 kg, respectively, and when rolling sleeves with conical ends under the pilgrim head, a decrease in their masses by 40 and 62 kg was obtained. those. the mass of the seed ends in the second and third cases is at the same level, and the mass of the pilgrim heads during rolling of the pipes according to the proposed method is less by 22 kg, because when rolling pipes from sleeves with a wall thickness of less than 60 mm, the ends collapse, i.e. increase in the mass of saw-gim heads. Pipes 377 × 9 mm in size were rolled on a pilgrim mill made of sleeves stitched using the existing technology with an average feed of sleeves into the deformation zone m = 19.6 mm. The load on the drive of the pilgrim mill during the steady rolling process increased from 5.0 to 6.5 kA. When rolling the sleeves stitched according to the patent No. 2261151, the load on the mill drive also increased from 5.0 to 6.5 kA with an average value of the supply of sleeves to the deformation zone m = 20.0 mm. Rolling conical sleeves on a pilgrim mill according to the proposed method was carried out with an average feed m = 20.5 mm. Due to the smooth decrease in the elongation along the length of the sleeves, the load on the drive of the piligim mill did not change significantly, namely it increased from the beginning to the end of rolling by 0.5 kA. A similar picture was obtained when rolling pipes of size 426 × 10 mm from ingots of size 585/540 × 1700 mm. The average mass of the seed ends was reduced in the second case by 20.1 kg, and by the proposed method by 20.5 kg, i.e. is on the same level. The average weight of the pilgrim heads was, respectively, 308, 236 and 231 kg. The fluctuation of the loads on the pilgrim mill drive ranged from 5.5 to 6.0 kA, versus 5.5 to 7.0 kA according to the existing method of flashing sleeves and according to patent No. 2261151, which made it possible to carry out the process of rolling pipe lashes with one value feeding the sleeves into the deformation zone from the beginning of rolling to the end, namely 19.25 mm versus 18.75, which makes it possible to increase the productivity of the pilgrim mill by 2.7% while reducing the transverse difference in the pipes.

Thus, the table shows that according to the proposed method for the production of hot-rolled thin-walled pipes 377 × 9 and 426 × 10 mm in size in pipe rolling plants with pilgrim mills, a decrease in the expenditure coefficient of the metal, respectively, by 10.4 is obtained relative to the method according to patent No. 2261151 and 12.0 kg per ton of pipe. The implementation of this method will stabilize the flow rate, reduce the lateral difference in the pipes and reduce the average value of fluctuations in the loads on the drive of the pilgrim mill from 8.0 to 8.5%.

Using the proposed method will reduce metal consumption by reducing the weight of the pilgrim heads and lateral difference when rolling lashes with fixed feed rates, increase the performance of the pilgrim installations by increasing the average feed rates, and eliminate crushing of the rear ends of the sleeves by determining the theoretically necessary hoods.

Data on piercing ingots with a diameter of 15 and 16 "in a cross-rolling mill, rolling pipes of 377 × 9 and 426 × 10 mm in size on TPU 8-16" with pilgrim mills and delivery of pipes rolled according to existing and proposed technologies

Table 1 Pipe size Ingot size Type of technol. Sleeve firmware Pilgrim mill pipe rolling Medium majesty
on filing Mandrel Diameter Sleeve Size (L) - Cylindrical Section The size of the sleeves (L _i ) - the seed end The size of the sleeve (L ₂ ) - under the pilgrim head Σ sleeve length Average pipe length Average weight Average economy, metal Mill Drive Load Length Wall Stretch. Length Wall Stretch. Length Wall Stretch. n / goal Exp. of the ends mm mm - mm mm mm - mm mm - mm mm - mm mm kg kg kA mm 377 × 9 555/505 × 1700 Existing 375 3330 75 1.95 - - - - - 3330 31500 245 41.5 - from 5.0 to 6.5 19.6 RF patent No. 2261151 375 2380 75 1.95 600 50-75 2.93-1.95 500 75-55 1.95-2.78 3480 32,400 205 28.6 52.9 5.0 to 6.5 20,0 Proposed 375 - - - 420 60-75 2.53-1.95 3180 75-65 1.95-2.34 3600 32700 183 28.8 74.7 from 5.0 to 5.5 20.5 426 × 10 585/540 × 1700 Existing 425 3140 80 1.84 - - - - - - 3140 27600 308 57.3 - from 5.5 to 7.0 18.75 RF patent No. 2261151 425 2230 80 1.84 600 60-80 2,56-1,84 500 80-60 1.84-2.56 3330 28600 236 37,2 93.1 from 5.5 to 7.0 18.75 Proposed 425 - - - 530 60-80 2,56-184 3000 80-65 1.84-2.34 3530 28900 231 36.8 97.5 from 5.5 to 6.0 19.25

Claims (3)

1. A method for the production of seamless hot-rolled pipes in tube-rolling plants with pilgrim mills, comprising heating ingots to a temperature of plasticity and flashing them in a cross-helical mill into sleeves with different hoods along the length µ _pr , µ _pr1 and µ _pr2, rolling the sleeves i size on a pilgrim mill to tubes of j size with a constant feed rate m _ij with a steady rolling process and hoods µ _pg1ij , µ _pg2ij , and µ _pg3ij , respectively, when seeding, a steady rolling process and during the removal of pilgrims heads from the conical parts of the sleeves at the end of rolling cutting pipe weaves into pipes - cutting and removal of technological waste - pilgrim heads and seed ends with a hot cutting saw, characterized in that the ingot blanks in the cross-helical rolling mill are stitched into sleeves having the shape two hollow combined truncated cones, one of which has a length equal to (0.10-0.15) of the sleeve length, and a smaller base is located at the front end along the sleeve firmware, the second cone has a length equal to (0.85-0 , 9) the length of the sleeve, and its smaller warping is located at the rear end along the sleeves firmware. 2. The method according to claim 1, characterized in that the piercing of the ingot blanks into conical combined hollow sleeves is carried out by reducing the hood from µ _pr1 to µ _pr , due to the smooth roll of the work rolls relative to the firmware axis from the beginning of the firmware — the smaller base of the first truncated cone to a greater extent, by the value of l, the value of which is determined from the expression:
$$l=\frac{D-d}{2}$$

,
where D is the outer diameter of the rear end of the conical sleeve of the first hollow truncated cone - the diameter of the larger base of the first hollow truncated cone, mm;
d - the external diameter of the front end of the taper sleeve - the diameter of the smaller base of the first hollow frustoconical mm, and a subsequent increase in drawing from μ _ave to μ _np2 by gradually details of the work rolls relative EEPROM axis from the greater base of the second truncated cone to the lower base by an amount l ₁ , the value of which is determined from the expression:
$$l_{\mathrm{one}}=\frac{D-d_{\mathrm{one}}}{2}$$

,
where d ₁ is the outer diameter of the rear end of the conical sleeve is the diameter of the smaller base of the second hollow truncated cone, mm 3. The method according to claim 1, characterized in that seeds are formed from the front ends of the liners, and pilgrim heads are formed from the rear ends.