CN117206334A - Production method of hot rolling multiple continuous reducing process for large-caliber ultra-thick wall seamless steel tube - Google Patents
Production method of hot rolling multiple continuous reducing process for large-caliber ultra-thick wall seamless steel tube Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 73
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- 238000000034 method Methods 0.000 title claims abstract description 57
- 230000008569 process Effects 0.000 title claims abstract description 52
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 35
- 238000005098 hot rolling Methods 0.000 title claims abstract description 20
- 238000005096 rolling process Methods 0.000 claims abstract description 261
- 230000006835 compression Effects 0.000 claims description 49
- 238000007906 compression Methods 0.000 claims description 49
- 238000010438 heat treatment Methods 0.000 claims description 35
- 238000004513 sizing Methods 0.000 claims description 22
- 230000009467 reduction Effects 0.000 claims description 20
- 238000009749 continuous casting Methods 0.000 claims description 19
- 239000011148 porous material Substances 0.000 claims description 14
- 241000733322 Platea Species 0.000 claims description 12
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- 239000007787 solid Substances 0.000 claims description 7
- 241000695274 Processa Species 0.000 claims description 5
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 239000002918 waste heat Substances 0.000 claims description 2
- 238000005242 forging Methods 0.000 description 10
- 239000002994 raw material Substances 0.000 description 9
- 239000002184 metal Substances 0.000 description 7
- 238000012545 processing Methods 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- 238000009785 tube rolling Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
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- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Abstract
A production method of a large-caliber ultra-thick-wall seamless steel tube by hot rolling multiple continuous reducing process relates to the technical field of seamless steel tube skew rolling. The primary cross rolling perforation reducing rolling, the secondary cross rolling perforation reducing rolling, the cross rolling reducing rolling pipe, the cross rolling reducing leveling and the online diameter setting (reducing) are continuously carried out on line to obtain the large-diameter super-thick-wall seamless steel pipe, the physicochemical comprehensive performance and the grain size grade of the produced super-thick-wall seamless steel pipe with the large diameter (D/S less than or equal to 14.5) meet the standard requirements, and the steel pipe quality has higher straightness and dimensional accuracy.
Description
Technical Field
The invention relates to the technical field of seamless steel tube skew rolling, in particular to a process production method for hot rolling and repeated continuous reducing rolling of a large-caliber ultra-thick-wall seamless steel tube.
Background
The traditional seamless steel pipe production line comprises a skew rolling perforating machine, a reducing mill (optional), a skew rolling tube mill, a skew rolling equalizing machine and a sizing mill, and the production process flow is generally as follows: and (3) selecting a solid tube blank with the diameter smaller than or equal to the outer diameter of the finished steel tube or similar to the outer diameter of the finished steel tube, sequentially performing hole expansion by a skew rolling perforating machine, a skew rolling tube mill and a skew rolling equalizing machine, and finishing sizing by a sizing mill to obtain the finished seamless steel tube.
For a seamless steel pipe with large caliber and super thickness (D/S=6-11, wherein D is the outer diameter of the steel pipe, S is the wall thickness of the steel pipe), the technical characteristics of matching and oblique rolling diameter expansion are basically adopted (forging stock or rolling stock) in process technology setting, and the quality of a product is stably ensured for meeting 6.2.3.3 total extension control regulation in the GB/T5310 standard in the application of the traditional oblique rolling process method; the purchase cost of the round tube blank raw material (forging blank or rolling blank) selected in the earlier stage is high.
However, with the continuous development of industries such as the national nuclear power industry, the boiler industry, the thermal power industry and the like, the requirements of special heavy caliber ultra-thick wall seamless steel pipes for supercritical and ultra-high pressure are increasing, while the existing metal extension processing deformation of the hot rolling of the seamless steel pipe production line is generally equal diameter or expanded diameter perforation rolling process production mode, when the hot rolling cross rolling deformation is in an extension state, the original process parameters are matched with the process capability of the distance between guide plates in metal extension change, if the distance between the guide plates is too small, only equal diameter or expanded diameter rolling can be realized, and the reducing deformation cannot be realized, if the distance between the guide plates is too large, the bearing friction of tool guide plates is greatly increased, the guide plates are extremely easy to adhere to metal, so that the defects of spiral scratch or spiral cover warping of the outer surfaces of the steel pipes occur in the rotation deformation process of the steel pipes, the tool wear rapidly and the consumption is extremely large, and the processing of the ultra-thick wall seamless steel pipes with large caliber (D/S=6-11 is the outer diameter of the steel pipes) is limited.
If the continuous reducing production method of hot rolling for many times is adopted for the large-diameter continuous casting blank raw material, the requirement of 3-5.2 of total process extension can be met, and the requirement of 6.2.3.3 total extension control regulation in GB/T5310 standard is met; the outer diameter of the piercing-rolling is easy to press down, rolling resistance of the guide plate to small-extension metal extension deformation is also reduced, piercing-rolling quality is stable, abrasion consumption of the tool guide plate is reduced, and service life is prolonged.
However, the conventional tandem rolling piercing mill, reducing mill (optional), tandem rolling mill and tandem rolling leveler are mainly used for equal-diameter or expanded-diameter rolling, and cannot meet the production requirements of large-diameter ultra-thick-wall seamless steel pipes, and if a plurality of continuous reducing devices are newly configured, the purchase cost is high.
Disclosure of Invention
The invention aims to overcome the technical defects of continuous reducing rolling by the existing multiple sets of skew rolling mill sets, and provides a method for producing a large-caliber ultra-thick wall seamless steel tube by sequentially performing skew rolling reducing perforation rolling, skew rolling secondary reducing perforation, skew rolling reducing tube rolling, skew rolling reducing averaging and online sizing on a raw material of a forging stock (rolling stock) for replacing a large-diameter continuous casting round tube blank.
The production method of the hot rolling multiple continuous reducing process of the large-caliber ultra-thick wall seamless steel tube is characterized by comprising the following steps of:
step 1), diameter is D Blank Heating the continuous casting solid round pipe blank to a temperature range of 1230+/-50 ℃, and then performing one-time skew rolling and reducing piercing rolling to obtain a hollow billet with an outer diameter D1 and a temperature of 1160 ℃ -1220 ℃, wherein the outer diameter range D 1 =D Blank -D Blank *（0.02～0.045）；
Diameter D of the continuous casting round tube blank Blank Satisfy formula (1)
；
Wherein D is the outer diameter of the formed seamless steel pipe, S is the wall thickness of the formed seamless steel pipe;
step 2), performing secondary oblique rolling and reducing perforation rolling on the hollow billet to obtain a hollow billet with an outer diameter D2 and a temperature of 1100-1160 ℃, wherein the outer diameter D2 = D1-D1 (0.02-0.045);
step 3), performing oblique rolling and reducing rolling on the pierced billet obtained in the step 2) to obtain a pierced billet with an outer diameter D3 and a temperature of 1040-1100 ℃, wherein the outer diameter D3 = D2-D2 (0.02-0.045);
step 4), performing oblique rolling, reducing and leveling on the pierced billet obtained in the step 3) to obtain a pierced billet with an outer diameter D4 and a temperature of 980-1040 ℃, wherein the outer diameter D4 = D3-D3 (0.02-0.045);
step 5), on the basis of the waste heat of the pierced billet after reducing and leveling in the step 4), heating the pierced billet in a temperature-controlled manner, and controlling the temperature of the pierced billet to be 910-1020 ℃;
and 6) carrying out longitudinal sizing rolling on the pierced billet with the temperature controlled at 910-1020 ℃ to obtain a finished seamless steel pipe with the outer diameter D and the temperature controlled at 820-930 ℃.
Further, the outer diameter and the wall thickness of the finished seamless steel tube meet the formula that D/S=6-11 range, and the outer diameter of the finished seamless steel tube is 615-914 mm; d is the outer diameter of the formed seamless steel pipe, and S is the wall thickness of the steel pipe.
Further, the specification of the continuous casting solid round tube blank in the step 1) is as follows: the diameter is 700 mm-1100 mm, the length is 1900 mm-4600 mm, and the total heating time is 24.5-h-45 h.
Further, in the steps 1) and 2), the two-roll skew rolling piercing mill is adopted to carry out primary skew rolling reducing piercing rolling and secondary skew rolling reducing piercing rolling.
Further, in the step 3), a taper roll two-roll skew rolling mill is adopted for performing skew rolling and reducing rolling; and step 4), adopting a two-roller skew rolling leveling machine to perform skew rolling reducing leveling.
Further, in the step 5), 18 continuous medium-frequency coil heating furnace sets are adopted for penetrating type temperature control heating, and the total heating time is 8-20 min.
And further, in the step 6), a three-roller five-frame sizing mill is adopted to carry out sizing longitudinal rolling on the pierced billet.
Further, the two-roll skew rolling piercing mill rolls in a one-pass skew rolling reducing piercing rolling processCone angle of roll entry sectiona In 1 Length ofl 1-1 The formula (2) of the reduction of the maximum incoming material diameter is satisfied
；
The two-roll oblique rolling perforating machine is used for reducing the cone angle of the roller inlet section in the secondary oblique rolling reducing perforating rolling processa In 1 Length ofl 1-1 The reduction formula (3) of the maximum incoming material diameter is satisfied
；
Cone angle of roller inlet section of two-roller skew rolling tube milla In 2 Length ofl 1-2 The formula (4) of the reduction of the maximum incoming material diameter is satisfied
；
Cone angle of roller inlet section of the two-roller skew rolling milla In 3 Length ofl 1-3 The formula (5) of the reduction of the maximum incoming material diameter is satisfied
。
Further, the positions d1 of the guide plate compression bands in the two-roll oblique-rolling perforation machine in the steps 1) and 2) correspond to the positions of the pore throats z2-1 of the roller compression bands in the radial direction, and the outlet angles of the guide plates are equal to the positions of the pore throats of the roller compression bandsa 2-1 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 1 ，a 2-1 =a Go out 1 – (0°～0.5°) ；
The guide plate compression band position d2 of the two-roller skew rolling tube mill in the step 3) corresponds to the position of the pore throat z2-2 of the roller compression band of the deformation zone in the radial direction, and the outlet angle of the guide platea 2-2 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 2 ，a 2-2 =a Go out 2 – (0°～0.5°) ；
Step 4) the guide plate compression belt position d3 of the two-roller skew rolling mill corresponds to the position of the pore throat z2-3 of the roller compression belt of the deformation zone in the radial direction, and the outlet angle of the guide platea 2-3 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 3 ，a 2-3 =a Go out 3 – (0°～0.5°)。
Further, in the steps 1) and 2), controlling the wall reduction amount of the primary oblique rolling reducing piercing rolling and the secondary piercing reducing rolling to be less than or equal to 5mm; controlling the wall reducing amount of reducing rolling to be less than or equal to 4mm in the step 3); and in the step 4), controlling the wall reducing amount of the skew rolling reducing and leveling to be less than or equal to 4mm.
The invention has the beneficial effects that:
the positions of the guide plate compression bands of the two-roller oblique rolling perforating machine, the two-roller oblique rolling tube mill and the two-roller oblique rolling leveling machine correspond to the positions of the pore throats of the roller compression bands in the radial direction, so that the pressure-bearing friction stress of the positions of the guide plate compression bands is weakened when the metal of the pore throats of the two-roller oblique rolling perforating machine, the two-roller oblique rolling tube mill and the two-roller oblique rolling leveling machine is extruded by the roller top to be elliptically and longitudinally extended; meanwhile, the cone angle of the guide plate outlet is smaller than the cone angle of the roller outlet, and the formula is satisfied:a 2 =a out of - (0-0.5 degrees) so as to effectively limit the extension of the transverse deformation of the steel pipe, and the reduction control can be effectively realized by matching with the reduction value range which is less than or equal to the reduction value range; meanwhile, the rolling resistance of the guide plate bearing small extension metal extension deformation can be reduced, the piercing-rolling quality is stable, the abrasion consumption of the tool guide plate is reduced, the service life is prolonged, and the defects of the prior art are overcome.
The process production method of the invention changes the local structure of the equipment on the existing piercing-rolling and expanding supporting equipment, so that the equipment can be suitable for the technical process of continuous oblique rolling and reducing piercing-rolling processing deformation, overcomes the defect that the existing multi-set oblique rolling unit equipment cannot continuously reduce the diameter, has low transformation cost and does not need to purchase a new production line at high price.
Meanwhile, the invention also widens the selection requirement of the raw materials of the ultra-thick wall seamless steel tube with large caliber (D/S=6-11); the large-diameter continuous casting blank can be selected as the raw material, and the existing forging blank (rolling blank) raw material process can be considered; meanwhile, in terms of energy conservation, compared with the prior art, the method of forging and rolling square billets or casting billets to obtain round billets (forging billets or rolling billets) directly saves the comprehensive manufacturing cost of raw material forging billets (rolling billets) by about 2000 yuan/ton; the production circulation period of the material for processing the forging stock (rolling stock) is saved by about 35 days.
The production method of the invention accords with 6.2.3.3 total extension control regulation in GB/T5310 standard, and the produced ultra-thick wall seamless steel tube with large caliber (D/S=6-11) has good quality and high dimensional accuracy, and is suitable for producing seamless steel tubes with finished product outer diameter of 615-914 mm; meanwhile, a large-diameter continuous casting blank can be selected as a raw material, the existing forging blank (rolling blank) raw material process can be considered, and the quality of the steel pipe has higher dimensional accuracy.
Drawings
FIG. 1 is a view showing the spatial position of a roll and a guide plate during reducing rolling by a two-roll oblique rolling piercing mill according to the present invention;
FIG. 2 is a central cross-sectional view of a longitudinal section of a guide plate during reducing rolling by a two-roll oblique-rolling piercing mill;
FIG. 3 is a view showing the spatial position of the rolls and guide plates in the reducing rolling of the tapered roll two-roll skew rolling mill of the invention;
FIG. 4 is a central cross-sectional view of a longitudinal section of a guide plate during reducing rolling by a tapered roller two-roll skew rolling mill.
FIG. 5 is a view showing the spatial positions of the rolls and guide plates in the reducing rolling by the two-roll skew-rolling mill according to the present invention;
FIG. 6 is a center cross-sectional view of a longitudinal section of a guide plate during reducing rolling by a two-roll skew rolling mill;
fig. 7 is a schematic view showing a primary bite of a tube blank in a primary skew rolling reducing piercing rolling process;
fig. 8 is a schematic view showing a state of primary biting of a work in a secondary skew rolling reducing piercing rolling process;
FIG. 9 is a schematic view showing a primary bite of a pipe blank in a skew rolling and reducing pipe rolling process;
fig. 10 is a schematic view showing a state of one-time biting of a work in a skew rolling reducing and leveling process.
Detailed Description
The invention provides a production method of a hot rolling multiple continuous reducing process of a large-caliber ultra-thick wall seamless steel tube, which comprises the following steps:
1) Heating a tube blank:
step 1), diameter is D Blank The continuous casting round tube blank is placed in a 35 m annular furnace for heating, the specification range of the continuous casting solid round tube blank (the continuous casting solid round tube blank is preferable, and a forging blank or a rolling blank can be adopted) is (the diameter is 700 mm-1100 mm multiplied by the length is 1900 mm-4600 mm), the total heating time length is generally 24.5 h-45 h according to the steel type and the diameter, and the heating temperature is 1230+/-50 ℃.
2) Primary reducing perforation:
performing primary oblique rolling reducing piercing rolling on the heated and insulated continuous casting round tube blank by a two-roller oblique rolling piercing machine to obtain a blank tube with an outer diameter D1 and a temperature of 1160-1220 ℃, wherein the outer diameter D1 = D Blank -D Blank *（0.02～0.045）；
Diameter D of the continuous casting round tube blank Blank Satisfy formula (1)
；
Wherein D is the outer diameter of the formed seamless steel pipe, S is the wall thickness of the formed seamless steel pipe;
3) Secondary reducing perforation:
performing secondary oblique rolling reducing perforation rolling on the hollow billet subjected to the primary oblique rolling reducing perforation by a two-roller oblique rolling perforating machine to obtain a hollow billet with the outer diameter D2 and the temperature of 1100-1160 ℃, wherein the outer diameter D2 = D1-D1 (0.02-0.045);
4) Reducing tube rolling by skew rolling:
performing oblique rolling and reducing rolling on the pierced billet through a tapered roller two-roller oblique rolling tube mill to obtain a pierced billet with an outer diameter D3 and a temperature of 1040-1100 ℃, wherein the outer diameter D3 = D2-D2 (0.02-0.045);
5) Reducing and leveling of skew rolling
Performing oblique rolling reducing and leveling on the pierced billet by a two-roller oblique rolling leveling machine to obtain a pierced billet with an outer diameter D4 and a temperature of 980-1040 ℃, wherein the outer diameter D4 = D3-D3 (0.02-0.045);
6) Temperature controlled heating
And (3) carrying out penetrating type temperature control heating on the pierced billet through 18 continuous medium frequency coil heating furnace sets, wherein the total heating time is 8-20 min, and the control temperature is 910-1020 ℃.
7) Online sizing
And 6) sizing and longitudinally rolling the pierced billet with the temperature controlled at 910-1020 ℃ in the step 6) through a three-roller five-frame sizing mill to obtain a finished seamless steel pipe with the outer diameter D and the temperature ranging from 820-930 ℃, wherein the first-fifth groups of three rollers of the three-roller five-frame sizing mill with different hole patterns form a long half shaft, a short half shaft and an elliptical average diameter of the elliptical hole, and the sizes are shown in table 1.
Hole type specification table 1 of three-roller five-frame sizing mill (unit mm)
The two-roll skew rolling perforating machine, the two-roll skew rolling tube mill and the two-roll skew rolling leveling machine in the technical process of the invention are designed and configured according to the design standard of the perforating machine.
In the process of the invention, the wall reduction amount of the primary oblique rolling reducing piercing rolling and the secondary piercing reducing rolling in the steps 2) and 3) is controlled to be less than or equal to 5mm; controlling the wall reducing amount of the skew rolling reducing rolled pipe to be less than or equal to 4mm in the step 4); and in the step 5), controlling the wall reducing amount of the skew rolling reducing and leveling to be less than or equal to 4mm.
As shown in figures 1-10, the two-roll skew-rolling perforating machine, the two-roll skew-rolling tube mill and the two-roll skew-rolling leveling machine in the technical process of the invention are all provided with a pair of rollers and a pair of guide plates, which belong to the prior known equipment, the rollers of the two-roll skew-rolling perforating machine, the two-roll skew-rolling tube mill and the two-roll skew-rolling leveling machine are conical rollers, the position d1 of the guide plate compression belt in the two-roll skew-rolling perforating machine corresponds to the position z2-1 of the hole throat of the roller compression belt in the radial direction, and the outlet angle of the guide platea 2-1 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 1 ，a 2-1 =a Go out 1 – (0°～0.5°) 。
The guide plate compression band position d2 of the two-roller skew rolling tube mill corresponds to the position z2-2 of the pore throat of the roller compression band of the deformation zone in the radial direction, and the outlet angle of the guide platea 2-2 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 2 ，a 2-2 =a Go out 2 – (0°～0.5°) 。
The guide plate compression belt position d3 of the two-roller skew rolling mill corresponds to the position of the hole throat z2-3 of the roller compression belt in the radial direction, and the outlet angle of the guide platea 2-3 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 3 ，a 2-3 =a Go out 3 – (0°～0.5°)。
The control of the outlet angle of the guide plate aims to match with the adjustment and change of the guide plate spacing parameter when the small extension metal is deformed in an extending way, so that the outer diameter of the reducing rolling process can be effectively controlled.
The two-roll oblique rolling perforating machine has the cone angle of the inlet section of the middle roll in the primary oblique rolling reducing perforating rolling processa In 1 Length ofl 1-1 The formula (2) of the reduction of the maximum incoming material diameter is satisfied
；
The two-roll oblique rolling perforating machine has the cone angle of the inlet section of the roller in the secondary oblique rolling reducing perforating rolling processa In 1 Length ofl 1-1 The reduction formula (3) of the maximum incoming material diameter is satisfied
；
Cone angle of roller inlet section of two-roller skew rolling tube milla In 2 Length ofl 1-2 The formula (4) of the reduction of the maximum incoming material diameter is satisfied
；
Cone angle of roller inlet section of the two-roller skew rolling milla In 3 Length ofl 1-3 The formula (5) of the reduction of the maximum incoming material diameter is satisfied
。
The invention discloses a two-roll oblique rolling perforating machine, a two-roll oblique rolling tube mill and a two-roll oblique rolling homogenizing machine which are configured in the process, wherein the outlet angle of the roll surface of a process roll is configured and used according to 2.5-4 degrees, which is the outlet angle of the roll surface of a roll for enlarging the diameter perforation and the diameter-enlarging rolled tube which are commonly and conventionally used by a plurality of steel tube enterprises in China, and is a method for reducing and piercing based on the existing outlet angle facilities of the roll surface of the process roll.
First embodiment
In the embodiment, the continuous casting round tube blank with the specification of finished products of 914 multiplied by 120mm, the steel number of P91 and the diameter of 1100mm (the diameter of the tube blank meets the formula)This embodiment will be specifically described.
The process of this example is as follows:
1) Placing a continuous casting round tube blank with the diameter of 1100mm in a 35 m annular furnace for heating, heating at the temperature of 1230+/-50 ℃ for 38.5-h-45 h, and then performing primary oblique rolling reducing perforation rolling by a two-roll oblique rolling perforation machine to obtain a blank tube with the outer diameter of D1, the temperature of 1160-1220 ℃ and the wall thickness of 133mm, wherein D1=1066mm;
2) Performing secondary oblique rolling reducing piercing rolling on the hollow billet by a two-roller oblique rolling piercing mill to obtain a hollow billet with the outer diameter of D2, the temperature of 1100-1160 ℃ and the wall thickness of 128mm, wherein D2=1032 mm;
3) Performing oblique rolling and reducing rolling on the pierced billet by a two-roller oblique rolling tube mill to obtain a pierced billet with the outer diameter D3, the temperature of 1040-1100 ℃ and the wall thickness of 124mm, wherein D3=1008 mm;
4) Step 3) performing oblique rolling reducing and leveling on the obtained pierced billet through a two-roller oblique rolling leveling machine to obtain a pierced billet with the outer diameter D4, the temperature of 980-1040 ℃ and the wall thickness of 120mm, wherein D4=985 mm;
5) Step 4) performing temperature control heating on the obtained pierced billet by 18 continuous medium frequency coil heating furnace sets, wherein the total heating time length is generally 18+/-2 minutes according to the steel grade and the diameter, and the temperature of the pierced billet is controlled and ensured to be 910-1020 ℃;
6) And (3) longitudinally rolling the pierced billet subjected to temperature control and heating by a three-roller five-frame sizing mill (hole pattern data are shown in table 1) to obtain a thermal finished steel pipe with an outer diameter of 928.8mm, a temperature of 820-930 ℃ and a wall thickness of 120.5mm, wherein the outer diameter is 915.9mm after cooling.
As a further explanation of this embodiment, the present embodiment is to implement the reducing process of the present invention after modifying an existing production line for expanding a seamless steel pipe, where the original production line includes a two-roll piercing mill of [ 800 ], a two-roll pipe mill of [ 960 ], a huge dragon homomixer, a continuous medium frequency coil heating furnace set, and a three-roll sizing mill of [ 914 ], where the three-roll sizing mill of [ 914 ] configures a matched hole-type frame according to the outer diameter of a commonly used national standard, and includes hole-type sets of [ 711 mm, 762 mm, 813 mm, 864 mm, 914mm ]; the non-standard finished product outer diameter matching hole type with the finished product outer diameter of 615-914 mm can be configured according to the requirement.
In the process of the embodiment, the plugs used for the two-roll skew rolling perforating machine, the two-roll skew rolling tube mill and the two-cone roll skew rolling leveling machine are designed and configured according to the design standard of the plug of the perforating machine.
In this embodiment, the two-roll oblique rolling perforation machine, the two-roll oblique rolling tube mill, and the rollers and guide plates of the two-roll oblique rolling mill are reconfigured as required, wherein the primary oblique rolling reducing perforation process and the secondary oblique rolling reducing perforation process are completed by the two-roll oblique rolling perforation machine, and specific configuration parameters are as follows:
as shown in fig. 1-10, the roll entry section cone angle of a two roll oblique roll perforatora In 1 =3° lengthl 1-1 1550mm, the spacing between the compression belts when the rolls of two-roll oblique-rolling piercing mills are pressed down is c 1 ，c 1 =957mm, reducing threading in one skew rollingIn the hole rolling process, when two rollers are pressed down, the length of the roller surface between the primary biting point of the tube blank and the roller compression belt= 1366.17mm, where->(belonging to the common general knowledge),l 1-1 ＞l 2-1 simultaneously satisfy the formulaEnsuring the smooth biting of the tube blank.
In the secondary oblique rolling reducing perforation rolling process, when two secondary perforation rollers are pressed down, the length of the roller surface between the primary biting point of the workpiece and the roller compression belt(belonging to the common general knowledge),l 1-1 ＞l 2-2 simultaneously satisfy formula->Ensuring the smooth biting of the workpiece.
Cone angle of roller inlet section of two-roller skew rolling tube milla In 2 =3° lengthl 1-2 When two rollers of the two-roller skew-rolling mill are pressed down, the distance between the compression belts is set to be c =1150 mm 2 ，c 2 When two rollers of the two-roller skew-rolling tube mill are pressed down, the length of the roller surface between the primary biting point of the workpiece and the roller compression belt is calculated(belonging to the common general knowledge),l 1-2 ＞l 2-3 simultaneously satisfy formula->Ensuring the smooth biting of the workpiece.
Cone angle of roller inlet section of two-roller skew-rolling milla In 3 =3° lengthl 1-3 Setting two rollers =1150 mmWhen two rollers of the skew rolling mill are pressed down, the distance between the compression belts is c 3 ，c 3 When two rollers of the two-roller skew-rolling mill are pressed down, the length of the roller surface between the primary biting point of the workpiece and the roller compression belt is calculated(belonging to the common general knowledge),l 1-3 ＞l 2-4 simultaneously satisfy formula->Ensuring the smooth biting of the workpiece.
The position d1 of the guide plate compression belt in the two-roller oblique rolling perforating machine corresponds to the position z2-1 of the hole throat of the roller compression belt in the radial direction, and the outlet angle of the guide platea 2-1 Roll outlet roll surface angle =2.8°a Go out 1 =3°, satisfy the formulaa 2-1 =a Go out 1 - (0 DEG-0.5 DEG).
The position d2 of the guide plate compression band in the two-roller skew rolling tube mill corresponds to the position z2-2 of the hole throat of the roller compression band in the radial direction, and the outlet angle of the guide platea 2-2 =3.2°, roll exit face anglea Go out 2 =3.5° satisfying the formulaa 2-2 =a Go out 2 - (0 DEG-0.5 DEG).
The position d3 of the guide plate compression belt in the two-roller skew rolling mill corresponds to the position z2-3 of the pore throat of the roller compression belt in the radial direction, and the outlet angle of the guide platea 2-3 Roll outlet roll surface angle =2.7°a Go out 3 =3°, satisfy the formulaa 2-3 =a Go out 3 - (0 DEG-0.5 DEG).
Specific process detail parameters of the first embodiment are shown in table 2 below:
first example specific process parameter data table 2 (in mm)
Second embodiment
In the embodiment, the continuous casting round tube blank with the finished product specification of 615 multiplied by 56mm, the steel number of P92 and the diameter of 750mm (the diameter of the tube blank meets the formula) This embodiment will be specifically described as an example.
The process of this example is as follows:
1) Heating a continuous casting round tube blank with 750mm in a 35-meter annular furnace, heating 26 h-30 h at the temperature of 1230+/-50 ℃, and then performing primary oblique rolling reducing perforating rolling by a two-roll oblique rolling perforating machine to obtain a blank tube with the outer diameter D1, the temperature of 1160-1220 ℃ and the wall thickness of 63mm, wherein D1=733 mm;
2) Performing secondary oblique rolling reducing piercing rolling on the hollow billet by a secondary oblique rolling piercing mill to obtain a hollow billet with the outer diameter D2, the temperature of 1100-1160 ℃ and the wall thickness of 60mm, wherein D2=712 mm;
3) Performing oblique rolling and reducing rolling on the pierced billet through a two-roller oblique rolling tube mill to obtain a pierced billet with the outer diameter D3, the temperature of 1040-1100 ℃ and the wall thickness of 58mm, wherein D3=687mm;
4) Step 3) performing oblique rolling reducing and leveling on the obtained pierced billet through a two-roller oblique rolling leveling machine to obtain a pierced billet with the outer diameter D4, the temperature of 980-1040 ℃ and the wall thickness of 56mm, wherein D4=662 mm;
5) Step 4) performing temperature control heating (neglecting temperature drop in the transportation process) on the obtained pierced billet by 18 continuous medium frequency coil heating furnace sets, wherein the total heating time length is generally 10+/-2 minutes according to the steel grade and the diameter, and the pierced billet temperature is controlled and ensured to be 910-1020 ℃;
6) And (3) longitudinally rolling the pierced billet subjected to temperature control and heating by a three-roller five-frame sizing mill (hole pattern data are shown in table 1) to obtain a thermal finished steel pipe with an outer diameter of 625.6mm, a temperature of 820-930 ℃ and a wall thickness of 56.6mm, and cooling to obtain a finished steel pipe with an outer diameter of 619mm.
The embodiment realizes the diameter reduction process after modifying a certain seamless steel pipe expanding production line, and the original production line comprises a 800-roll oblique-rolling perforating machine, a 960-roll oblique-rolling pipe mill, a huge-dragon equalizing machine, a continuous medium-frequency coil heating furnace group and a 914 three-roll sizing mill, wherein the 914 three-roll sizing mill is provided with a frame according to the production size requirement of the seamless steel pipe with the finished product specification of 615 multiplied by 56 mm.
In the process of the embodiment, the two-roll oblique rolling perforating machine, the two-roll oblique rolling tube mill and the two-cone roll oblique rolling leveling machine are designed and configured according to the design standard of the perforating machine, wherein the primary oblique rolling reducing perforation process and the secondary oblique rolling reducing perforation process are completed through the two-roll oblique rolling perforating machine.
In this embodiment, the rolls and guide plates of the two-roll skew rolling piercing mill, the two-roll skew rolling pipe mill, and the two-roll skew rolling leveler are reconfigured as required, and specific configuration parameters are as follows:
as shown in fig. 1-10, the roll entry section cone angle of a two roll oblique roll perforatora In 1 =3° lengthl 1-1 1550mm, the spacing between the compression belts when the rolls of two-roll oblique-rolling piercing mills are pressed down is c 1 ，c 1 In the primary skew reduction piercing rolling step, the roll surface length between the primary bite of the tube blank and the roll compression strip is measured at the time of rolling down two rolls =652.5 mm(belonging to the common general knowledge),l 1-1 ＞l 2-1 simultaneously satisfy the formulaEnsuring the smooth biting of the tube blank.
In the secondary oblique rolling reducing piercing rolling process, when two secondary piercing rolls are pressed down, the length of the roll surface between the primary biting point of the workpiece and the compression belt of the secondary piercing rollsWherein->(belonging to the common general knowledge),l 1-1 ＞l 2-2 simultaneously satisfy formula->Ensuring the smooth biting of the workpiece.
Cone angle of roller inlet section of two-roller skew rolling tube milla In 2 =3° lengthl 1-2 When two rollers of the two-roller skew-rolling mill are pressed down, the distance between the compression belts is set to be c =1150 mm 2 ，c 2 When two rollers of a two-roller skew tube rolling mill are pressed down, the length of the roller surface between the primary workpiece biting point and the roller compression belt of the skew-reduced tube rolling roller is calculated(belonging to the common general knowledge),l 1-2 ＞l 2-3 simultaneously satisfy the formulaEnsuring the smooth biting of the workpiece.
Cone angle of roller inlet section of two-roller skew-rolling milla In 3 =3° lengthl 1-3 When the two rolls of the two-roll skew-rolling mill are pressed down, the distance between the compression belts is set to be c 3 ，c 3 When two rollers of the two-roller skew-rolling mill are pressed down, the length of the roller surface between the primary biting point of the workpiece and the roller compression belt is calculated(belonging to the common general knowledge),l 1-3 ＞l 2-4 simultaneously satisfy formula->Ensuring the smooth biting of the workpiece.
The position d1 of the guide plate compression belt in the two-roller oblique rolling perforating machine corresponds to the position z2-1 of the hole throat of the roller compression belt in the radial direction, and the outlet angle of the guide platea 2-1 Roll outlet roll surface angle =2.8°a Go out 1 =3°, satisfy the formulaa 2-1 =a Go out 1 - (0 DEG-0.5 DEG).
The position d2 of the guide plate compression band in the two-roller skew rolling tube mill and the position z2-2 of the pore throat of the roller compression band are in the radial directionThe upward positions are corresponding to the outlet angles of the guide platesa 2-2 =3.2°, roll exit face anglea Go out 2 =3.5° satisfying the formulaa 2-2 =a Go out 2 - (0 DEG-0.5 DEG).
The position d3 of the guide plate compression belt in the two-roller skew rolling mill corresponds to the position z2-3 of the pore throat of the roller compression belt in the radial direction, and the outlet angle of the guide platea 2-3 Roll outlet roll surface angle =2.7°a Go out 3 =3°, satisfy the formulaa 2-3 =a Go out 3 - (0 DEG-0.5 DEG).
Specific process detail parameters for the second example are shown in table 3 below:
specific process parameter data table 3 for the second example (unit mm)
Through finished product detection, the deviation range of the nominal wall thickness S of the seamless steel tube prepared by the first and second embodiments is less than or equal to +/-8%, the deviation range of the nominal outer diameter D is about 0 to +7mm, and the finished seamless steel tube has higher dimensional accuracy and meets the standard specified tolerance requirement; the total extension of the processing deformation of the process method accords with the (6.2.3.3 total extension control rule in GB/T5310 standard);
the embodiment shows that the large-caliber (D/S=6-11) ultra-thick wall seamless steel tube produced by the production method of the multiple continuous reducing process is suitable for producing seamless steel tubes with finished outer diameters of 615-914 mm, has large total reducing amount and total process extension control of 3-5.2, and accords with 6.2.3.3 total extension control regulation in GB/T5310 standard; in terms of product specification and size precision, the sizing mill is longitudinally rolled in the forming process, so that the flatness of the spiral corrugation on the outer surface caused by the deformation of the two-roller skew rolling can be eliminated to the greatest extent, and the seamless steel tube has higher size precision, reasonable and reliable process method and obvious cost reduction effect through comprehensive finished product inspection.
In summary, the production method of the invention adopts the continuous reducing process of hot rolling, and can completely meet various technical requirements of standards after being matched with the later on-line cooling control implementation technology or the heat treatment implementation technology of different materials, such as the dimensional accuracy and the comprehensive physicochemical performance of the ultra-high pressure large-caliber ultra-thick wall seamless steel pipes for boiler pipes, thermal power chemical pipes and the like.
Although the invention has been described in connection with implementations, it will be apparent to those of ordinary skill in the art that various modifications may be made to the implementations described above without departing from the spirit and scope of the claims.
Table 4 (unit mm) for group spacing configuration of specific products of the invention
According to table 4, the tube stock of the corresponding specification can be directly selected according to the specification of the finished product.
Claims (10)
1. The production method of the hot rolling multiple continuous reducing process of the large-caliber ultra-thick wall seamless steel tube is characterized by comprising the following steps of:
step 1), diameter is D Blank Heating the continuous casting solid round pipe blank to a temperature range of 1230+/-50 ℃, and then performing one-time skew rolling and reducing piercing rolling to obtain a hollow billet with an outer diameter D1 and a temperature of 1160 ℃ -1220 ℃, wherein the outer diameter D1 = D Blank -D Blank *（0.02～0.045）；
Diameter D of the continuous casting round tube blank Blank Satisfy formula (1)
；
Wherein D is the outer diameter of the formed seamless steel pipe, S is the wall thickness of the formed seamless steel pipe;
step 2), performing secondary oblique rolling and reducing perforation rolling on the hollow billet to obtain a hollow billet with an outer diameter D2 and a temperature of 1100-1160 ℃, wherein the outer diameter D2 = D1-D1 (0.02-0.045);
step 3), performing oblique rolling and reducing rolling on the pierced billet obtained in the step 2) to obtain a pierced billet with an outer diameter D3 and a temperature of 1040-1100 ℃, wherein the outer diameter D3 = D2-D2 (0.02-0.045);
step 4), performing oblique rolling, reducing and leveling on the pierced billet obtained in the step 3) to obtain a pierced billet with an outer diameter D4 and a temperature of 980-1040 ℃, wherein the outer diameter D4 = D3-D3 (0.02-0.045);
step 5), on the basis of the waste heat of the pierced billet after reducing and leveling in the step 4), heating the pierced billet in a temperature-controlled manner, and controlling the temperature of the pierced billet to be 910-1020 ℃;
and 6) carrying out longitudinal sizing rolling on the pierced billet with the temperature controlled at 910-1020 ℃ to obtain a finished seamless steel pipe with the outer diameter D and the temperature controlled at 820-930 ℃.
2. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: the outer diameter and the wall thickness of the finished seamless steel pipe meet the formula that D/S=6-11, and the outer diameter of the finished seamless steel pipe is 615-914 mm.
3. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: the specification of the continuous casting solid round tube blank in the step 1) is as follows: the diameter is 700 mm-1100 mm, the length is 1900 mm-4600 mm, and the total heating time is 24.5-h-45 h.
4. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: and (2) adopting a two-roll oblique rolling perforating machine to carry out primary oblique rolling reducing perforation rolling and secondary oblique rolling reducing perforation rolling in the steps 1) and 2).
5. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: in the step 3), a two-roller skew rolling tube mill is adopted for skew rolling and reducing rolling; and step 4), adopting a two-roller skew rolling leveling machine to perform skew rolling reducing leveling.
6. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: in the step 5), 18 continuous medium-frequency coil heating furnace sets are adopted for penetrating type temperature control heating, and the total heating time is 8-20 min.
7. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: and 6) sizing and longitudinally rolling the pierced billet by adopting a three-roller five-frame sizing mill.
8. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: the two-roller oblique rolling perforating machine is used for reducing the cone angle of the roller inlet section in the primary oblique rolling reducing perforating rolling processa In 1 Length ofl 1-1 The formula (2) of the reduction of the maximum incoming material diameter is satisfied
；
The two-roll oblique rolling perforating machine is used for reducing the cone angle of the roller inlet section in the secondary oblique rolling reducing perforating rolling processa In 1 Length ofl 1-1 The reduction formula (3) of the maximum incoming material diameter is satisfied
；
Cone angle of roller inlet section of two-roller skew rolling tube milla In 2 Length ofl 1-2 The formula (4) of the reduction of the maximum incoming material diameter is satisfied
；
Cone angle of roller inlet section of the two-roller skew rolling milla In 3 Length ofl 1-3 The formula (5) of the reduction of the maximum incoming material diameter is satisfied
。
9. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: the positions of the guide plate compression bands d1 in the two-roller oblique-rolling perforating machine in the steps 1) and 2) correspond to the positions of the pore throats z2-1 of the roller compression bands in the radial direction, and the outlet angles of the guide plates are equal to the positions of the pore throats z2-1 of the roller compression bandsa 2-1 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 1 ，a 2-1 =a Go out 1 - (0 ° -0.5 °); the guide plate compression band position d2 of the two-roller skew rolling tube mill in the step 3) corresponds to the position of the pore throat z2-2 of the roller compression band of the deformation zone in the radial direction, and the outlet angle of the guide platea 2-2 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 2 ，a 2-2 =a Go out 2 – (0°～0.5°) ；
Step 4) the guide plate compression belt position d3 of the two-roller skew rolling mill corresponds to the position of the pore throat z2-3 of the roller compression belt of the deformation zone in the radial direction, and the outlet angle of the guide platea 2-3 The angle of the outlet roller surface of the corresponding roller is less than or equal toa Go out 3 ，a 2-3 =a Go out 3 – (0°～0.5°)。
10. The production method of the hot rolling multiple continuous reducing process for the large-caliber ultra-thick-wall seamless steel tube, which is characterized by comprising the following steps of: controlling the wall reduction amount of the primary oblique rolling reducing piercing rolling and the secondary piercing reducing rolling in the steps 1) and 2) to be less than or equal to 5mm; controlling the wall reducing amount of reducing rolling to be less than or equal to 4mm in the step 3); and in the step 4), controlling the wall reducing amount of the skew rolling reducing and leveling to be less than or equal to 4mm.
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