55results about How to "Small ellipticity" patented technology

The invention relates to a heat spraying aluminium zinc alloy wire rod composition and its preparing process, wherein the constituents (by weight percentage) of the wire rod include Al 54-56%, 0.004%<=M<=1.08%, impurity whose total amount is less than 1%, and balancing Zn, M is any one or the combination of RE, Mg, Ti or B.

The invention discloses a cold-drawing and cold-rolling mixed molding method of a stainless steel seamless pipe. The method comprises the following steps: preparing a pierced billet; cutting off the head and the tail of the pierced billet; pickling a pierced billet blank for the first time; coping, cold rolling and unoiling the pickled blank; judging whether the requirements of the finished product are met or not; if so, carrying out annealing treatment; lubricating and cold-drawing a welding head (drive head) of the annealed steel pipe semi-finished product; carrying out solid solution heat treatment on the finished product; straightening, fixing and chopping the finished product; pickling the finished product; carrying out finished product inspection, wherein the finished product inspection comprises the steps: surface inspection, water pressure detection, eddy current inspection, ultrasonic flaw detection, intergranular corrosion testing, grain size testing, tension test, expansion test, flattening test, hardness test, and carbon and sulfur analysis. The stainless steel seamless pipe manufactured by the method is accurate in size, small in ovality and good in quality.

The invention discloses a method for processing orientation-deflected seed crystals. The method includes selecting crystal ingots meeting specific requirements and determining directions of main reference planes according to growth edge lines; performing primary rounding processing by a rounder; precisely positioning the main reference planes by an X-ray orientation diffraction instrument and finding OF planes of orientation deflection; performing adjusted orientation deflection cutting for an end surface of each crystal ingot by an internal dicing saw to meet specified requirements on the orientation deflection and parallelly cutting another end surface of the crystal ingot; performing secondary rounding processing according to the orientation-deflected end surfaces; perpendicularly extracting seed crystals from the processed crystal ingots by a milling machine and a seed crystal extracting device; performing clamped surface processing, chemical polishing and cleaning for the extracted seed crystals to obtain the orientation-deflected seed crystals. By using the orientation-deflected seed crystals processed by the method for producing orientation-deflected silicon wafers, the processing yield can be effectively increased, the yield of the wafers from crystal bars in unit weight can be effectively increased, and the silicon wafer chamfering processing efficiency can be effectively improved.

The invention discloses a technique for sizing thick-walled seamless steel tubes through a two-roller skew rolling mill. The sizing technique comprises the steps of (1) adjusting the milling roller distance of the two-roller skew rolling mill to enable the milling roller distance to be 1.01-1.05 times of the outer diameter of a finished steel tube, and adjusting the guide disk distance of the two-roller skew rolling mill to enable the guide disk distance to be 1.02-1.10 times of the roller distance; and (2) sleeving a crude tube on a sizing core rod of the two-roller skew rolling mill, and conducting sizing and rolling and obtaining the thick-walled seamless steel tubes under the action of milling rollers and guide disks. During sizing and rolling, the portion, in contact with the milling rollers, of the crude tube serves as a rolled section, and a gap is always reserved between the inner wall of the rolled section and the sizing core rod. According to the sizing technique, the cost of a sizing skew rolling mill is saved, only core rods with the appropriate diameters are needed, the producing cost is greatly saved, and the sale prospect is improved. Furthermore, the sized seamless steel tubes have the beneficial effects of being high in geometric dimension accuracy, good in straightness and free of crack. The invention further discloses a technique for rolling the thick-walled seamless steel tubes through the two-roller skew rolling mill.

The invention relates to a method for manufacturing a special-shaped ring forge piece of a large wind power flange. According to the method for manufacturing the special-shaped ring forge piece of the large wind power flange, a bar is adopted to serve as a workblank, the workblank in a reasonable shape is obtained by conducting upsetting and punching on the workblank, a rectangular section in the axial direction of a fire diameter and two fire closed cavity special-shaped sections are rolled on the well manufactured workblank in the reasonable shape, and the required part is finally obtained through machining. According to the method for manufacturing the special-shaped ring forge piece of the large wind power flange, metal of all portions in the radial direction and the axial direction of the workblank is distributed three times through upsetting, rolling of the rectangular section and rolling of the special-shaped section. When the method is used for manufacturing the large wind power generation tower flange, the utilization rate of material is high, the production efficiency is high, a larger amount of subsequent machining time is saved, the metal of all the portions, in the radial direction and the axial direction, of the forge piece is evenly distributed, the structural property existing after thermal processing is improved, the quality is stable, and the method is particularly suitable for efficient and mass production of large wind power flanges.

The invention discloses a bend forming method of a large-angle pipeline with high precision, a large pipe diameter and a small bending diameter ratio, and belongs to the technical field of machining. Metal or alloy materials with the low melting temperature are machined to be a core rod, the core rod is assembled into an inner hole of the large pipeline to be bent, the large pipeline and the core rod are simultaneously bent through bend forming, pipe blank which is subjected to bend forming is heated to be at the temperature higher than the melting temperature of the alloy core rod, at a certain temperature below the AC1 temperature of a bent pipe material (or the heating temperature at which the performance of the pipe blank material can not drop obviously), a core rod material in the bent pipe is molten and flows out, and the large bent pipe with the bent section ovality being small, the inner hole surface being smooth and the inner arc being capable of not wrinkling is acquired. The bent pipe low-melting-point core rod technology is suitable for the bend forming of the large-angle pipeline which is high in forming precision requirement, thick in wall, large in pipe diameter and small in bending diameter ratio.

The invention provides a two-step induction heater of a bent tube for oil gas pipeline production, and a method thereof. The apparatus comprises a tube pushing mechanism, a bending mechanism, an electromagnetic induction heating mechanism and a cooling system, wherein double induction coils are arranged in the electromagnetic induction heating mechanism, a first induction coil is used to preheat a tube, a second induction coil is used to further heat the tube on the basis of preheating, and the bending system is used to bend the tube, so the mechanical properties of the bent tube obtained after bending are effectively improved, and many problems frequently appearing in present induction heated bent tube production are solved. The apparatus and the method can be used to produce induction heated bent tubes for high-performance oil gas pipeline production, can improve the tube heating uniformity in the bending process and the production efficiency of the bent tube, improve the dimension precision of the induction heated bent tube, and have the advantages of uniform heating and high production efficiency, and the bent tube produced in the invention has the advantages of excellent performances, small deformation, small ovality and low residual stress.

The invention discloses a flexible sealing structure of a rotary air pre-heater. The flexible sealing structure is a contact type sealing device and comprises a sealing sliding block, a regulation supporting seat and a supporting fixing plate; the sealing sliding block is rotatablely connected with the supporting fixing plate; the supporting fixing plate is relatively arranged on a radial baffle plate of the air pre-heater fixedly; the regulation supporting seat is fixedly connected with the supporting fixing plate; a compression spring is arranged between the regulation supporting seat and the sealing sliding block; the sealing sliding block is in contact with a fan-shaped plate or an axial arc-shaped plate of the air pre-heater; a reset regulation device is arranged between the sealing sliding block and the regulation supporting seat; two ends of the reset regulation device are respectively connected with the sealing sliding block and the regulation supporting seat; and the reset regulation device is used for regulating the maximal resilience modulus of the compression spring positioned between the sealing sliding block and the regulation supporting seat. By using the flexible sealing structure, through regulating the reset regulation device, the regulation of sealing acting force between a moving component and a stationary component in the air pre-heater is realized; the wear of a sealing surface is decreased; and the service life of a quick-wear part is prolonged.

The invention discloses a wiring cutter head. The wiring cutter head comprises a cutter body, wherein a cutter point is arranged on one side of the cutter body; the lower part of the cuter point is a cutter setting surface; the vertical distance between the front side of the cutter setting surface and the point end of the cutter point is 0.1 mm; one end of the cutter setting surface is a diagonal cutting surface inclined towards the direction of the cutter point. The invention further discloses a method for preparing a wire exposed type electric smelting pipe fitting and the obtained electric smelting pipe fitting; the method comprises turning and wiring steps. The thickness of the cutter setting surface is added, the vertical distance between the front side of the cutter setting surface and the cutter point of the cutter head is shortened, the copper wire arrangement depth is shortened, the diagonal cutting surface is arranged on the cutter setting surface, and one side flange is compressed but another side flange is not pressed when the cutter setting surface is used for grinding a copper wire, so that the firmness of the copper wire is guaranteed, a part of the copper wire is exposed outside the inner surface of a plastic pipe fitting and is in good contact with the pipe fitting, the process is realized through the cooperation with a corresponding technology, and the obtained wire exposed type electric smelting pipe fitting is reasonable in copper wire arrangement, firm in the copper wire and small in ellipticity.

The present invention relates to a manufacture method of angle pipe and its special equipment. It is characterized by that one end of steel pipe to be bent is fixed on the mould wheel, the position to be bent and deformed is tightly held by mould wheel, and another end of said steel pipe can be driven by acting force produced by hydraulic or mechanical driving device, so that the steel pipe can be moved forwards and can be bent to form angle pipe.

The invention belongs to the technical field of aluminum alloy materials for air separators, in particular to a manufacturing method of a 6A02T651 aluminum alloy seam pipe for a low-temperature oxygen / nitrogen air separator, more particularly to a manufacturing method of a 6A02T651 (phi 411*30) aluminum alloy seam pipe. According to the manufacturing method, online quenching production of an ultralarge-diameter and large-wall-thickness seam pipe material for an air separator is realized; under the condition that the standard requirements are met, the labor productivity is raised, the cost is reduced and the ordering requirements of users are met.

The invention provides a high-precision bar rolling mill. The high-precision bar rolling mill comprises a base and a roller system. The roller system and the base are mounted and fixed through a roller system support. A conical hole and four grooves are formed in each stand column of the base of the rolling mill. Adjusting liner plates are arranged in the grooves. Vertical boss structures matched with the four grooves in each stand column of the base of the rolling mill are arranged on the four sides of the roller system support. An assembly gap between the roller system support and the stand columns of the base can be adjusted by tightly pressing screws through the adjusting liner plates. Semi-conical holes are formed in the middles of bosses of the roller system support and matched with the conical holes in the stand columns of the base of the rolling mill. The roller system support and the base of the rolling mill are locked through conical drift bolts. The high-precision bar rolling mill is compact in structure, easy to dismount and mount, high in rigidity, small in bounce value and free of axial displacement; round bar products rolled through the high-precision bar rolling mill are high in section size precision, small in ovality and especially suitable for production of bars; and domestication and batch manufacturing of the high-precision bar rolling mill can completely replace an import mode, and great economic and social benefits are achieved.

The invention relates to a production method for electron welding wire of 0.8-4.0mm diameter and its apparatus, which is characterized in the following steps: equipping squeezing barrel, squeezing module, heating element, temperature sensor and reducing die in squeezing head of squeezing press; controlling electronic instrument, relay and actuator by temperature sensor and digital temperature display; power set and heating element compositing temperature detect and control system with control range of 400-420 deg C. The product produced by this technology has the properties of high compatibility of diameter, fineness, rich-looking and quality, and end breaking and self-igniting never happen in the procedure of production.

The invention relates to a tubular electrode with high speed perforated pores, which comprises an outer tube of which the inside is provided with an inner core axially. Further, the inner core and the outer tube are fixed into an integral structure by stretching. Further, the inner core runs through the circle center of the outer tube. Further, the inner core is a rectangular structure which runs through the diameter of the outer tube. Further, the inner core is an integral structure consisting of three fan-shaped tubes with the same semi-diameter, and the semi-diameter of the fan-shaped tube is half of the internal diameter of the outer tube. As a preferred mode, the fan angle of each of the three fan-shaped tubes is 120 degrees, thus not only the processing speed can be improved, but also the electrical conductivity of the outer tube electrode in use can be improved. The tubular electrode is provided with the inner core to not only effectively remove the middle part of the processing pore of the work piece, but also reduce the consumption of the electrode when the electrode is used and consumed. The tubular electrode has the advantages of fast processing speed, good surface smooth finish, high straightness, small ellipticity, good mechanical property and the like.

The invention relates to the field of steel pipe production, in particular to a plug for punching of large-hole series medium- and thick-wall capillaries. The outline of the plug consists of a punching section, an expanding section, a rolling section, a circling section and a reverse cone section. The front end surface of the plug adopts a flat head design, and a bar inserting hole is formed on the tail end of the plug; connection between the front end surface of the plug and the punching section is realized through arc transition, wherein the arc radius is R2, and the arc radius of the outline of the punching section is R3; the expanding section and the rolling section are cones, wherein the taper of the expanding section is a2, and the taper of the rolling section is a1; the outline of the reverse cone section is an arc of which the arc radius is R1; and the circling section is a cylinder.

The invention provides a manufacturing method of a pressure-bearing equipment thick-wall seal head structure. The problem of the discontinuity of the outer surface due to outer surface and slope machining or transition is solved. The main technological process includes the steps that re-inspection of a steel plate is qualified; workblank blanking is carried out; heating is carried out; a head is hot-pressed; heat treatment is carried out; edging is carried out; the shape and position dimensions of an inner sphere are inspected by a template; turning of a circular seam groove 4 and an inner surface 1 is carried out, and slight turning and finishing for the groove outside surface are carried out; and thickness measuring is carried out. The outer surface of the seal head is smooth and continuous, the ovality of the inner surface after machining is decreased, the size of an internal groove is even, and the inner and outer surfaces of the seal head are of good quality.

The invention relates to the technical field of sintering furnaces, and in particular relates to a high-temperature sintering furnace. The high-temperature sintering furnace comprises a furnace body with a heating bar, a workpiece vehicle, a driving mechanism and a lifting mechanism, wherein the workpiece vehicle is arranged at the bottom of the furnace body; the driving mechanism is used for driving the workpiece vehicle to travel; and the lifting mechanism is used for lifting the workpiece vehicle. The high-temperature sintering furnace is characterized in that refractory bricks are tiled at the upper part of the workpiece vehicle along the length direction of the workpiece vehicle; the upper parts of the refractory bricks are provided with hollow refractory bricks; and the hollow refractory bricks are axially and radially provided with through holes respectively. The refractory bricks and the hollow refractory bricks are arranged on the workpiece vehicle, because the through holes are arranged in the hollow refractory bricks, each part of a TC (tungsten carbide) bearing can obtain uniform heat during the heating process, meanwhile, the bottom of the TC bearing in cooling can be cooled down uniformly, the product quality and amount are improved by 50% above, the product hardness is 260-280 degrees, and the ovality is reduced by 40% above.

The invention discloses a drawing system for an MCP (Multi-Chip Packaging) optical fiber drawing machine and a drawing method thereof. The system comprises a laser diameter measuring instrument, a computer, a PCI bus controller card, a terminal board, a first servo driver, a first servo motor, a second servo driver, a second servo motor, a first reduction gear, a second reduction gear and a drawing component, wherein the laser diameter measuring instrument is connected with the computer; the computer is connected with the PCI bus controller card; the PCI bus controller card is connected with the terminal board; the terminal board is connected with the first servo driver and the second servo driver; the first servo driver and the second servo driver are respectively connected with the first servo motor and the second servo motor; the first reduction gear and the second reduction gear are respectively arranged on the first servo motor and the second servo motor; and the first reduction gear and the second reduction gear are connected with the drawing component. The drawing system can reduce the ovality of the optical fiber and can increase the drawing precision and the stability of the shape of a cross section.

The hot sprayed Zn-Al alloy wire consists of Al 10-20 wt%, one or several of RE, Mg, Ti and B 0.006-1.5 wt% and impurity less than 1 wt%, except Zn. The preparation process of the hot sprayed Zn-Al alloy wire includes melting zinc ingot and aluminum ingot in an alloy smelting furnace and refining; adding intermediate alloy under stirring, letting stand, eliminating slag and continuous horizontal casting to obtain coarse Zn-Al alloy wire; homogenizing annealing and drawing to form Zn-Al alloy wire product. Spraying with the Zn-Al alloy wire can well protect base steel and prolong its service life.

The invention provides a position control system and method for an axial centering roller of a ring rolling mill. The position control system comprises a processing unit and a signal receiving module; the signal receiving module is used for transmitting received data to the processing unit; and the processing unit is used for acquiring data of the signal receiving module and running a computer program. The invention further relates to a control method of the system. In the rolling process of an annular forge piece, the real-time distance between the current position of the axial conical roller and the minimum rolling starting position of the axial conical roller and the real-time distance between the outer diameter detection device and the outer diameter of the annular forge piece are adopted, the real-time stroke of the centering roller can be accurately calculated, and the position of the axial centering roller is controlled through a hydraulic servo control system; and in the rolling process of the annular forge piece, the jumping and swinging phenomena of the annular forge piece are limited, the deviation force caused by asymmetric rolling is reduced, the ovality of the annular forge piece is reduced, a basis is provided for real-time diameter detection and roundness of the annular forge piece, and a basis is provided for stable proceeding of the rolling process.

The invention discloses a limiting device for heat treatment of a double-layer-structure welding assembly and a clamping method. The limiting device comprises an outer disc, an inner disc, a chassis,a centering shaft and a pressing plate, wherein the outer disc, the inner disc and the chassis are all disc parts with center holes and are assembled on the centering shaft; the peripheral surface ofthe outer disc is a first annular outer cylindrical surface; the first annular outer cylindrical surface is tightly attached to the inner surface of an outer layer structure of the double-layer-structure welding assembly; the peripheral surface of the inner disc is a second annular outer cylindrical surface; the second annular outer cylindrical surface is tightly attached to the outer surface of an inner layer structure of the double-layer-structure welding assembly; the pressing plate is connected with the upper end surface of the chassis through a first bolt; and an outer layer mounting edgeand an inner layer mounting edge of the double-layer-structure welding assembly are positioned between the pressing plate and the upper end surface of the chassis. The limiting device is adopted forclamping, so that the concentricity of the inner layer mounting edge and the outer layer mounting edge after heat treatment is guaranteed, the ovality of the inner layer mounting edge and the outer layer mounting edge is controlled, the concentricity of the inner layer mounting edge, the outer layer mounting edge and a large-end outlet section is guaranteed, the workload of calibration is reducedprior to turning, and the assembly requirements are met.

The invention discloses a cladding mould capable of enhancing combination degree of an outer winding pipe of a krah pipe. The cladding mould comprises a cladding mould body for cladding, a vacuum cylinder and a vacuum pump, the vacuum cylinder is fixed in the cladding mould body in a penetrating mode, and the vacuum pump is connected with the vacuum cylinder. According to the cladding mould capable of enhancing combination degree of the outer winding pipe of the krah pipe, the vacuum cylinder and the vacuum pump are added so that the outer winding pipe is tightly combined with a cladding layer during cladding, and the hardness of the krah pipe can be enhanced.

The invention discloses a non-tangent expansion round steel hole type and a production method, and relates to the field of a steel rolling technology. The non-tangent expansion round steel hole type is composed of a base circle and width expansion parts located on the two sides of the base circle. By means of a non-tangent expansion hole type technology, the size of a diagonal line of the hole type is minimum, and accordingly ovality is minimum. Rolled grooves are easy and convenient to machine and assemble, the ovality of produced high-precision round steel is not larger than 0.20 mm, and the requirement for ovality of high-precision bars is met. Meanwhile, the service life of the grooves is prolonged, mechanical equipment is simplified through the round steel hole type, the produced round steel is good in stability and high in automation degree, and production efficiency and product quality are greatly improved.

The invention discloses a mandrel for molding rubber pipes. The mandrel is used for molding the rubber pipes and comprises a central portion, a first layer portion and a second layer portion. The central portion is a cylinder; the first layer portion is a column with the cross section in the shape of a circular ring and is extruded and molded on the central portion; the second layer portion is a column with the cross section in the shape of a circular ring and is extruded and molded on the first layer portion. The mandrel has the advantages that the traditional single layer is changed into a double-layer or multilayer structure, accordingly, the quality of the molded mandrel can be greatly improved even on existing molding equipment, namely an extruding machine, the ellipticity of the mandrel can be lowered, and shrinkage marks on the surfaces of the mandrel can be reduced; novel molding production equipment does not need to be purchased, increase of complicated molding working procedures can be omitted, and increase of the production cost can be prevented; the recycling frequencies of the mandrel can be increased, accordingly, the service cost of the mandrel can be lowered, and the service life of the mandrel can be prolonged.

The invention discloses a TA16 titanium alloy wire processing process. The TA16 titanium alloy wire processing process comprises the following steps of: extracting, rolling, high-temperature rounding,high-temperature drawing and room-temperature drawing, thereby obtaining the TA16 titanium alloy wire with a diameter being Phi 1.0 mm. According to the TA16 titanium alloy wire processing process disclosed by the invention, the high-temperature rounding step is increased, so that ovality of the rolled wire is reduced through a wire rod with a diameter being Phi 9.5 mm while a rolled back-skin wire is heated to a high temperature being about 800 DEG C, and therefore, the yield is increased; the skin of the high-temperature rounded wire is pulled off through a centerless lathe, and skin of thehigh-temperature drawn wire is pulled off through high-temperature wire drawing, so that surface defects can be effectively reduced, and the surface grain size and roughness of the wire are ensured;and compared with a conventional process, the TA16 titanium alloy wire processing process has the advantages of cancelling a plurality of acid-floating and manual-grinding processes in a white-skin wire processing process as well as a process of performing acid-alkaline washing while the wire is drawn to be 3.0 mm, so that the environmental protection purpose is realized, and working hours can bereduced by 1 / 3.

The invention discloses pipe bending equipment and a bent pipe machining method for inhibiting a bent pipe from becoming elliptic. The pipe bending equipment comprises a guide seat and a plurality of movable joint pressing blocks, the guide seat is installed on a rack, the movable joint pressing blocks are distributed side by side and installed on the guide seat in a sliding mode, and semicircular grooves are formed in the right end faces of the movable joint pressing blocks. The semicircular grooves in the movable joint pressing blocks are matched to form a first semicircular groove. Before pipe bending operation is carried out, the first semicircular groove is linear and can be attached to the outer side wall of the linear part of the guide pipe. According to the technical scheme, when pipe bending operation is carried out, part of the movable joint pressing block can slide out of the guide seat, the first semi-circular groove can be bent along with the guide pipe, and then the first semi-circular groove can be attached to the outer side wall of the bent part of the guide pipe. The outer side wall of the bent part of the guide pipe is sufficiently supported, furthermore, the ellipticity of the bent part of the guide pipe is further reduced, and the outer side wall of the bent part of the guide pipe can be effectively prevented from being stretched and fractured.

The present invention discloses a limited device and clamping method for the heat treatment of double -layer structure welding composition. The limit device includes the outer disk, inner plate, chassis, attentive shaft, and pressure plate.The disk, and the three are assembled on the heart axis.The outer surface of the outer disk is a first ring -shaped outer cylinder, and the inner surface of the inner surface of the outer structure of the first ring -shaped outer cylinder and the double -layer structure welding is tight;The outer surface of the inner structure of the inner structure of the second ring -shaped outer cylinder and the double -layer structure welding is tight; the upper end of the chassis is set with a pressure plate connected by the first bolt, and the outer installation edges of the outer layer of the double -layer structure welding component areThe inner layer is installed between the upper end of the pressure plate and the upper end of the chassis.The restriction device of the present invention is used for the installation of the installation of the inner and outer layers of the inner and outer layers of the inner and outer layers of the inner and outer layers.A pre -school volume to ensure assembly requirements.

The invention particularly relates to an ultra-high strength and low stress aluminum alloy pipe and a preparation method thereof. The ultra-high strength and low stress aluminum alloy pipe is a 7xxx series aluminum alloy pipe, and a grain is in a long strip shape and has the characteristics that the length is 30 to 50mu m, the tensile strength is 618 to 748MPa, the yield strength is 568 to 702MPaand the ellipticity is 0.02 to 0.15mm. The preparation method comprises multistage quenching, slow stretching and multi-time cryogenic treatment. The mechanical properties of the aluminum alloy pipe obtained by the invention are significantly improved; compared with a conventional 7xxx aluminum alloy pipe, the aluminum alloy pipe obtained by the invention has the advantage that the tensile strength can be improved by about 12 percent at most. In addition, residual stress in a product prepared by the invention can be effectively eliminated and the deformation degree can be reduced to 1 / 25 thatof a conventional pipe at most, which show that the reduction effect of the residual stress is obvious; besides, the grain size of the product disclosed by the invention is effectively refined and thegrain length is only about half that of a conventional product.

The invention discloses a technique for sizing thick-walled seamless steel tubes through a two-roller skew rolling mill. The sizing technique comprises the steps of (1) adjusting the milling roller distance of the two-roller skew rolling mill to enable the milling roller distance to be 1.01-1.05 times of the outer diameter of a finished steel tube, and adjusting the guide disk distance of the two-roller skew rolling mill to enable the guide disk distance to be 1.02-1.10 times of the roller distance; and (2) sleeving a crude tube on a sizing core rod of the two-roller skew rolling mill, and conducting sizing and rolling and obtaining the thick-walled seamless steel tubes under the action of milling rollers and guide disks. During sizing and rolling, the portion, in contact with the milling rollers, of the crude tube serves as a rolled section, and a gap is always reserved between the inner wall of the rolled section and the sizing core rod. According to the sizing technique, the cost of a sizing skew rolling mill is saved, only core rods with the appropriate diameters are needed, the producing cost is greatly saved, and the sale prospect is improved. Furthermore, the sized seamless steel tubes have the beneficial effects of being high in geometric dimension accuracy, good in straightness and free of crack. The invention further discloses a technique for rolling the thick-walled seamless steel tubes through the two-roller skew rolling mill.

The invention provides a two-step induction heater of a bent tube for oil gas pipeline production, and a method thereof. The apparatus comprises a tube pushing mechanism, a bending mechanism, an electromagnetic induction heating mechanism and a cooling system, wherein double induction coils are arranged in the electromagnetic induction heating mechanism, a first induction coil is used to preheat a tube, a second induction coil is used to further heat the tube on the basis of preheating, and the bending system is used to bend the tube, so the mechanical properties of the bent tube obtained after bending are effectively improved, and many problems frequently appearing in present induction heated bent tube production are solved. The apparatus and the method can be used to produce induction heated bent tubes for high-performance oil gas pipeline production, can improve the tube heating uniformity in the bending process and the production efficiency of the bent tube, improve the dimension precision of the induction heated bent tube, and have the advantages of uniform heating and high production efficiency, and the bent tube produced in the invention has the advantages of excellent performances, small deformation, small ovality and low residual stress.