Abstract: An object of the present invention is to provide a rotary cutting tool, a method of cutting a billet for manufacturing a seamless pipe, and a method of manufacturing the seamless pipe, which are capable of restraining the occurrence of an outer surface flaw on the seamless pipe. A rotary cutting tool 100 in accordance with the present invention has substantially circular shape and is provided with a plurality of blade parts 1 along the outer peripheral portion thereof. The end face 11 on the downstream side in the direction of rotation of the blade part 1 tilts at an angle ? not smaller than 1 degree and not larger than 10 degrees with respect to the thickness direction Y intersecting at right angles to the direction of rotation X.

Abstract: Pipe-swelling can be prevented by piercing-rolling a high-alloy steel billet heated to a temperature range from 900 to 1250° C. with a piercing mill equipped with main rolls having a surface roughness Rmax of 150 to 500 ?m. A ratio (the gap WG of guide rolls/the gap WR of the main rolls) is preferably at 1.10 to 1.20. The difference (?P??R) is preferably set at 0 to 3.0°, where ?R is an angle between an exit-side face of each of the main rolls of the piercing mill and the pass line; and ?P is an angle between a rolling face of the piercing plug and the pass line.

Abstract: Disclosed is a method for producing a seamless pipe by using a piercing mill which pierces and rolls a round billet heated to 1300° C. or lower, wherein the piercing mill is composed of a pair of skew rolls disposed to face each other around a pass line, a pair of guide devices disposed to face each other around the pass line, and a plug disposed along the pass line, between the pair of the skew rolls and also between the pair of the guide devices, wherein the piercing-rolling is performed under the conditions satisfying the following formulas (1) to (3) to prevent wrinkle flaws of the seamless pipe: ?1.0<????(1) ??=?p??r??(2) ?0.37×??+1.47?Rn?0.37×??+2.

Abstract: a billet made of high Cr-high Ni alloy, which contains, by mass percent, 20 to 30% of Cr, 30 to 50% of Ni, and at least one element selected from Mo and W with a value “Mo+0.5W” of 1.5% or more is heated under conditions satisfying the following formula (1), and then the billet is pierced and rolled using an inclined roll type piercing mill with a roll gouge circumferential speed of 2.28 m/sec or higher. This prevents melted rash on the inner surface and lengthens the plug life. T?1575?4.45×Vf?104.7×{?ln(th/ro)}??(1) wherein T indicates a heating temperature (° C.) of the billet, Vf indicates the roll gouge circumferential speed (m/sec), ro indicates a radius (mm) of a billet at an entry-side, and th indicates a radial thickness (mm) of a pipe after piercing.

Abstract: There is provided a lubricant for hot plastic working, which contains 20 to 40 mass % of iron oxide and 10 to 30 mass % of sodium silicate, wherein impurities are 3 mass % or less, and the lubricant contains 40 to 60 mass % of water. By virtue of combined action of these components, the lubricant exhibits excellent lubricity and suppliability and does not adversely affect the corrosion resistance of product. The lubricant is suitably used for lubricating a guide shoe in piercing-rolling, for example, a high-Cr steel and achieves a great effect of preventing a seizure flaw from occurring on the outer surface of product by being applied directly to the outer surface of a workpiece just before piercing rolling, preferably, within one second before starting piercing rolling.

Abstract: An apparatus for sizing a pipe end comprising: a plug 3 for sizing the pipe end; a chuck 2 for clamping the pipe; and shifting means for shifting the position of the plug 3 and/the chuck 2, which are placed successively from the end of the pipe 2, and the plug 3 has a circular cross section, and is constituted by a taper portion 31 and a diameter equivalent portion 32 continuously formed from the tip of the plug in succession. The outer diameter of the taper portion 31 is gradually expanding from the tip toward the rear end while satisfying the following formulas (1) and (2). The chuck 2 is capable of changing clamping position of the pipe 1. This apparatus makes it possible to size the inner diameter of a pipe end with superior dimensional precision 22?LR/(D1×0.01/2)?115 ??(1) R2?R1 ??(2).

Abstract: A billet is provided on a pass line between a pusher and a plug, and the billet is advanced and caught between a plurality of inclined rolls. At least between when said caught billet contacts said plug and when the piercing and rolling reaches a steady state, the advancing speed of the billet is not less than the advancing speed of the billet when the piercing and rolling is carried out without pushing the billet forward by the pusher in the steady state. By this manufacturing method, inner surface defects at a tip end of a hollow shell can be restrained.

Abstract: A hole 30 is formed in the center of the rear end face 20 of a round billet 10. The hole 30 has a predetermined depth from the rear end face 20 and a plurality of grooves 31 are provided in the side surface thereof. Each groove 31 extends in the depth direction of the hole 30. Piercing and rolling of the round billet 10 having the hole 30 is performed using a piercing mill having a plug. During piercing and rolling, the bottom surface of the hole 30 is broken through by the plug and a protrusion which is to be the starting point of burrs is formed, and the protrusion is absorbed by the groove 31 as the plug advances. Consequently, formation of burrs at the rear end of a hollow shell after piercing-rolling thereof can be suppressed.

Abstract: Seamless pipes excellent in quality features with high productivity is made by a by carrying out piercing-rolling using a piercer provided with a pair of inclined rolls. The piercing-rolling is carried out under conditions such that the plug tip draft (TDFT) or the root of the product of the plug tip draft (TDFT) are controlled along with the number of billet revolutions (N), namely (TDFT×N)0.5. In addition, positions of the inclined rolls are controlled in connection with the gorge draft (GDFT) indicating the ratio of the roll gap (Rg) which is minimal in the gorge section between the inclined rolls to the billet outside diameter (Bd). The piercing-rolling is carried out using a plug having a particular shape.

Abstract: By using a plating bath containing chromic acid: 100 to 250 g/L, sulfate radical: 3.0 to 5.5 g/L, and a catalyst: 100 to 200% (a weight ratio to the chromic acid content) for conducting electroplating, a Cr-plating film which has an increased film crack density is formed on the surface of a mandrel bar base metal, whereby peeling-off of the Cr-plating film can be suppressed in mandrel mill rolling for extending the service life of the mandrel bar.

Abstract: A pusher device 4 includes a cylinder device 30 and a pusher mandrel 34. The cylinder device 30 includes a cylinder shaft 32. The pusher mandrel 34 is attached to the tip end of the cylinder shaft 32. The tip end of the pusher mandrel 34 is abutted against the rear end of a billet 20. The cross sectional area Sp of the pusher mandrel 34 and the cross sectional area Sb of the billet 20 satisfy Expression (1). The length Lp of the pusher mandrel 34 and the cross sectional area Sp of the pusher mandrel 34 satisfy Expression (2). The moving distance Lc of the tip end of the cylinder shaft 32 during piercing and rolling and the outer diameter Dc of the cylinder shaft 32 satisfy Expression (3). Therefore, the pusher device 4 can restrain the wall thickness deviation of the tip end part of a produced hollow shell. 0.3?Sp/Sb??(1) Lp/Sp?1.

Abstract: A plug 2 used for a piercer according to the invention includes a tip end portion 23, a cylindrical portion 24, a barrel portion 25, a mandrel coupling portion 22, and an injection hole 21. The injection hole 21 penetrates from the surface of the cylindrical portion 24 to the surface of the mandrel coupling portion 22 and an externally supplied lubricant is injected from the hole. A clearance forms between the pierced material and the cylindrical portion 24. The injection hole 21 is formed at the cylindrical portion 24, and therefore the material in the process of piercing does not contact the injection hole 21. Therefore, an inner surface defect attributable to the contact between the material and the injection hole 21 can be prevented from being generated.

Abstract: It is an object of the present invention to provide a monitoring apparatus and the like of seamless pipe or tube production conditions which enable to quickly correct production conditions during operating the manufacturing facilities of a seamless pipe or tube.

Abstract: A piercing and rolling plug has a film composed of oxides such as Fe3O4 and FeO and Fe (metal) as being formed on the surface of the base metal by electric arc spraying using an iron wire whose main component is Fe and, owing to this film, a plug excellent in heat-shielding and seizure-preventing effects can be realized and the lifetime of the plug can be prolonged. Further, in regenerating this plug, a film can be re-formed via the steps of shot blasting of the as-used plug in piercing and rolling and electric arc spraying in that order; thus, it is possible to regenerate the plug at low cost and in a short period of time.

Abstract: A mandrel mill is provided which can perform elongation rolling with a markedly increased working ratio and dimensional accuracy on a material which is inherently difficult to roll such as a hollow shell made of stainless steel or a thin-walled material. A mandrel mill for manufacturing a mother tube by performing elongation rolling of a hollow shell comprises a plurality of roll stands, having at least one 4-roll stand for wall thickness reduction of a hollow shell and at least one 2-roll stand including the final stand downstream of the 4-roll stand.

Abstract: Seamless pipes excellent in quality features with high productivity is made by a by carrying out piercing-rolling using a piercer provided with a pair of inclined rolls. The piercing-rolling is carried out under conditions such that the plug tip draft (TDFT) or the root of the product of the plug tip draft (TDFT) are controlled along with the number of billet revolutions (N), namely (TDFT×N)0.5. In addition, positions of the inclined rolls are controlled in connection with the gorge draft (GDFT) indicating the ratio of the roll gap (Rg) which is minimal in the gorge section between the inclined rolls to the billet outside diameter (Bd). The piercing-rolling is carried out using a plug having a particular shape.

Abstract: To provide a method and apparatus for seamless tubes in which the occurrence of material peeling can be prevented even when the skew angle ? and tube expansion ratio are increased. A piercing-rolling method for seamless tubes using a piercer, which is provided with a pair of cone-shaped main rolls and a pair of disk rolls, each pair being arranged in an opposing manner with a pass line therebetween as a center axis, and a plug whose center axis coincides with the pass line, wherein a billet to be pierced and rolled is advanced while being spirally rotated by a drive rotation of the main rolls; the method of which is characterized in each of the disk rolls being arranged in an inclined state at a fixed skew angle ? to the pass line.

Abstract: A metal pipe according to the invention has a plurality of ridges that have different heights, extend in the axial direction, and are arranged in the circumferential direction at its inner circumferential surface. If the Reynolds number changes and the streak structure and the scale of a hairpin vortex change, the streak and the hairpin vortex each match any one of the ridges. Therefore, the fluid friction can be reduced in a wide Reynolds number range.

Abstract: A high quality hollow shell in which the occurrence of internal surface flaws caused by the rotary forging effect and/or shear deformation is prevented by suppressing the rotary forging frequency and shear deformation in a transient region at the stage of billet gripping and a worsening of thickness deviations in the top portion of the hollow shell is also prevented is reliably produced with preventing miss-rolling such as incomplete billet gripping and troubles in bottom withdrawal and an increase in the outer diameter of the hollow shell in the bottom portion.

Abstract: A plug has a tip end portion, a taper portion, and a middle portion. The surface of the tip end portion is a spherical surface whose radius of curvature is R1 and length is L1 that is shorter than R1. The outer diameter of the taper portion on the front end side is D1, and the outer diameter on the back end side is D2 that is larger than D1, and the length is L2. The plug satisfies Expression (1), Expression (2) if 0<L1/R1<0.5 and Expression (3) if 0.5?L1/R1<1. The curve of the spherical surface of the tip end portion is gentler than that of the semi-spherical surface, and the diameter of a hole formed in a billet by the tip end portion is larger than that in the case of the semi-spherical surface. Therefore, the taper portion does not contact with the billet 0.5D1<L1+L2?2.5D1??(1) 1.0<D2/D1?1.4??(2) 1.0<D2/D1<1.8?0.8L1/R1??(3).

Abstract: The invention relates to an apparatus for making a seamless hollow body (10) from a solid round block (7) of steel with a diameter <95% of the diameter of the solid round block by means of a two-roll cross-rolling mill with a piercing mandrel (3) held between the inclined roll (1) and including a piercer (5) and at least one smoothing part (4) using pass-closing guides, or by means of a three-roll cross rolling mill with a piercing mandrel held between the inclined rolls and including a piercer and at least one smoothing part, wherein the distance of the rolls is adjusted in a particular manner at the narrowest cross-section (2) in relation to the diameter of the used round block, and the position of the piercing mandrel is adjusted in relation to the narrowest cross-section of the rollers.

Abstract: A rolling mill (10) for processing seamless tubes comprises a plurality of rolling units (U) that are sequentially arranged along a rolling axis (L), each of which is provided with at least three removable working rolls (12), which are each equipped with a groove (12a) for accommodating the tube to be worked; the rolling mill comprises a mandrel suitable to be fitted in the tube cavity during the process; the tube is worked by being sequentially passed, with the mandrel (22) fitted in the tube cavity, within the grooves (12a) of the rolls (12) of the rolling units (U) such that the outer diameter of the tube (T) is reduced; in order to have low capital and production costs, each rolling unit (U) has an unchanged nominal diameter

Abstract: A process for producing seamless pipes which comprises conducting a piercing rolling step, a elongating rolling step using a mandrel bar, and a sizing rolling step and subsequently conducting a product heat treatment. In the process, when the carbon-equivalent weight, namely the sum of the weight of graphite in the lubricant and the carbon content in the organic binder, per unit area of the lubricant adhering to the mandrel bar surface in the above-mentioned step of elongating rolling is expressed by C (g/m2) or the maximum extent of carburization in the inner surface of the pipe to be heat-treated but prior to the heat treatment is expressed by ?C (% by mass), the heating temperature for the pipe to be heat-treated is expressed by T (° C.

Abstract: The present invention provides a seamless tube piercing/rolling plug and a seamless tube producing method in which piercing/rolling is performed with an inclined rotary piercing mill while the seamless tube piercing/rolling plug is used as a piercing tool. The seamless tube piercing/rolling plug is used while a front part and a rear part of the split plug are held as an integral plug, at least the front part is made of low alloy steel, and oxide films are formed on surfaces of the front part and rear part. The present invention also provides a seamless tube piercing/rolling apparatus and a seamless tube producing method in which the front part and/or rear part is replaceable in a tube making process line using the seamless tube piercing/rolling apparatus.

Abstract: A high quality hollow shell in which the occurrence of internal surface flaws caused by the rotary forging effect and/or shear deformation is prevented by suppressing the rotary forging frequency and shear deformation in a transient region at the stage of billet gripping and a worsening of thickness deviations in the top portion of the hollow shell is also prevented is reliably produced with preventing miss-rolling such as incomplete billet gripping and troubles in bottom withdrawal and an increase in the outer diameter of the hollow shell in the bottom portion.

Abstract: It is a problem of the present invention to provide a method of manufacturing the seamless pipes having better mechanical properties, by means of a pipe manufacturing method with large energy-saving effect to continuously carry out processes from pierce-rolling to heat treatment. A method of manufacturing a seamless pipe comprising the steps of a pierce-rolling process, elongation rolling process, sizing process, reheating process, quenching process and tempering process, wherein the sizing process is completed with a temperature of the seamless pipe not less than 600° C. but less than 800° C., the seamless pipe is charged into a reheating furnace with a temperature not less than 400° C. and is reheated with a temperature not less than Ac3 transformation temperature but not grater than 1000° C. in the reheating process.

Abstract: A billet is provided on a pass line between a pusher and a plug, and the billet is advanced and caught between a plurality of inclined rolls. At least between when said caught billet contacts said plug and when the piercing and rolling reaches a steady state, the advancing speed of the billet is not less than the advancing speed of the billet when the piercing and rolling is carried out without pushing the billet forward by the pusher in the steady state. By this manufacturing method, inner surface defects at a tip end of a hollow shell can be restrained.

Abstract: A seamless tube is manufactured while effectively suppressing the occurrence of carburization in the seamless tube without interfering with operations. A seamless tube is manufactured by a step of washing at least a portion of a conveyor installed in a conveying step of a mandrel bar B which is situated from a lubricant applying device 7 to the entrance of a mandrel mill 8, a step of washing, on the upstream side of the lubricant applying device 7, a mandrel bar B which was used for elongation rolling, and a step of applying a non-graphite-based lubricant to the mandrel bar B with the lubricant applying device 7, wherein the conveyor and the mandrel bar B are each washed such that the amount of graphite C2 (g/m2) adhering to the surface of the mandrel bar B before it is provided to elongation rolling and the amount of carbon C1 (g/m2) contained in the organic binder of the applied lubricant satisfy Equation 1: 0.08×C1+0.05×C2?3 and Equation 2: 3?C1+C2?50.

Abstract: A plug has a tip end portion, a taper portion, and a middle portion. The surface of the tip end portion is a spherical surface whose radius of curvature is R1 and length is L1 that is shorter than R1. The outer diameter of the taper portion on the front end side is D1, and the outer diameter on the back end side is D2 that is larger than D1, and the length is L2. The plug satisfies Expression (1), Expression (2) if 0<L1/R1<0.5 and Expression (3) if 0.5?L1/R1<1. The curve of the spherical surface of the tip end portion is gentler than that of the semi-spherical surface, and the diameter of a hole formed in a billet by the tip end portion is larger than that in the case of the semi-spherical surface. Therefore, the taper portion does not contact with the billet. 0.5D1<L1+L2?2.5D1??(1) 1.0<D2/D1?1.4??(2) 1.0<D2/D1<1.8?0.

Abstract: [Objective] To provide a method and apparatus for seamless tubes in which the occurrence of material peeling can be prevented even when the skew angle ? and tube expansion ratio are increased. [Means for solution] A piercing-rolling method for seamless tubes using a piercer, which is provided with a pair of cone-shaped main rolls and a pair of disk rolls, each pair being arranged in an opposing manner with a pass line therebetween as a center axis, and a plug whose center axis coincides with the pass line, wherein a billet to be pierced and rolled is advanced while being spirally rotated by a drive rotation of the main rolls; the method of which is characterized in each of the disk rolls being arranged in an inclined state at a fixed skew angle ? to the pass line.

Abstract: A method is described for producing a cylindrical hollow body from a blank, with the workpiece being opened in the core region by successive swaging which is angularly offset against each other about the axis of the workpiece and being simultaneously pushed onto a piercing mandrel. In order to improve the piercing it is proposed that the workpiece is pressed during the swaging with a predeterminable axial force against the piercing mandrel which can be advanced against the workpiece against this axial force, which piercing mandrel is moved back to its initial position synchronous with the axial feed of the workpiece between the successive swaging steps.

Abstract: The present invention provides a seamless tube piercing/rolling plug and a seamless tube producing method in which piercing/rolling is performed with an inclined rotary piercing mill while the seamless tube piercing/rolling plug is used as a piercing tool. The seamless tube piercing/rolling plug is used while a front part and a rear part of the split plug are held as an integral plug, at least the front part is made of low alloy steel, and oxide films are formed on surfaces of the front part and rear part. The present invention also provides a seamless tube piercing/rolling apparatus and a seamless tube producing method in which the front part and/or rear part is replaceable in a tube making process line using the seamless tube piercing/rolling apparatus.

Abstract: A seamless tube producing method uses a piercing/rolling plug wherein piercing/rolling is performed with an inclined rotary piercing mill while the seamless tube piercing/rolling plug is used as a piercing tool. In one mode, a front part and a rear part of the split plug are held as an integral plug, the front part being made of low alloy steel, and oxide films are formed on surfaces of the front part and rear part. In a second mode, the front part and/or rear part are replaceable via a removable mounting wherein a mandrel bar holding the plug goes through the rear part, the mandrel bar being coupled with the front part. A thickness of the oxide film formed in the front part can be 200 ?m or more and the oxide film of the front part can be thicker than the oxide film of the rear part.

Abstract: A round billet containing, by mass %, 10.50 to 14.00% of Cr with a value represented by the equation of “Cr+4Si?(22C+0.5Mn+1.5Ni+30N)” of not more than 9.0%, wherein the symbols of the elements represent the contents, by mass %, of the elements in the steel, is heated at a soaking temperature of 1100 to 1250 ° C. so that an in-furnace time (min) is not less than “0.5×Diameter of the round billet (mm)”, and then pierced and rolled with a piercing efficiency by a piercing mill of not less than 50%, a value regulated by the equation: “{(Diameter of the round billet?Roll gap at the foremost end of the plug)/Diameter of the round billet}×100” of not more than 8.0, and a plug shape represented by the equation: “Radius of foremost end of the plug (mm)/Diameter of the round billet (mm)” of 0.06 to 0.17. The thus-manufactured high-Cr seamless steel pipe or tube has excellent internal surface properties with minimized internal surface defects.

Abstract: A seamless steel tube comprising, in mass %, C: 0.30 to 0.50%, Si: 0.5% or less, Mn: 0.3 to 2.0%, P: 0.025% or less, S: 0.005% or less, Cr: 0.15 to 1.0%, Al: 0.001 to 0.05%, Ti: 0.005 to 0.05%, N: 0.02% or less, B: 0.0005 to 0.01% and O (oxygen): 0.0050% or less, wherein Beff defined in following equation (a) or (b) takes a value of 0.0001 or more, where Beff=B?10.8×(N?14×Ti/47.9)/14—(a) when Neff=N?14×Ti/47.9?0, and Beff=B—(b) when Neff=N?14×Ti/47.9<0, thus enabling to provide seamless steel tubes having excellent cold workability, hardenability, toughness and torsion fatigue strength and being most suitable for hollow shaft blanks for use in making one-piece type hollow drive shafts as well.

Abstract: A process for producing a seamless steel pipe, in which the occurrence of inner surface flaws in the pipe can be reduced through the lowering of the friction coefficient during the elongation rolling by means of a mandrel mill is provided. The reduction of inner surface flaws is accomplished through the use of a lubricant composed mainly of either or both of graphite and mica coated to the surface of a mandrel bar, and another lubricant composed mainly of an alkali metal borate that is applied onto the inner surface of the hollow stock pipe. The temperature of the pipe prior to receiving the lubricant, during lubricant application, and prior to elongation rolling is controlled. The time between descaling or piercing and lubricant application and between lubricant application and elongation rolling is also controlled.

Abstract: A method for manufacturing a seamless pipe, capable of preventing the carburization phenomenon that occurs in a manufacturing process of pipe and simplifying an elongation rolling process, is provided. In this method, after piercing in the piercing rolling process, rolling is performed without using an inside regulating tool in the elongation rolling process, or without performing the elongation rolling followed by reducing rolling in a reducing rolling process, and thickening is then performed by use of a cold mill or cold draw bench in a cold rolling process. According to this method, the trap of graphite fine particles in the inner and outer surfaces of the pipe that took place in the conventional elongation rolling process can be minimized to prevent the carburization of the pipe. The method of the present invention is effective, particularly as a measure for preventing the carburization of an ultra-low carbon stainless steel or high alloy steel.

Abstract: A pierced shell of an austenitic stainless steel having a good inner surface condition is provided, and a means is established which can perform mass production on an industrial scale of a good quality seamless steel pipe of stainless steel. An austenitic stainless steel billet with a P content of at most 0.040% and an S content of at most 0.020% is pierced under conditions such that the pipe expansion ratio H (outer diameter of shell/diameter of billet to be worked) satisfies the following equation to obtain a tube shell of an austenitic stainless steel. {P(%)/(0.025×H?0.01)}2+{S(%)/(0.015×H?0.01)}2?1. When manufacturing a seamless steel pipe of an austenitic stainless steel, the above-described shell is rolled to form a pipe.

Abstract: A piercing method for manufacturing a seamless pipe capable of suppressing the rotary forging effects and suppressing the redundant shear strain without excessive narrowing of the roll diameter is provided. This method is characterized by holding a feed angle ? and a cross angle ? of main rolls in a range satisfying the following expressions (1) to (3), setting the relationship between outer diameter “d0” of the solid billet and the outer diameter “d” and thickness “t” of a hollow piece after piercing so as to satisfy the following expression (4), and further setting the relationship between inlet diameter D1 and outlet diameter D2 of the main roll with the above-mentioned “d0”, “d” and ? so as to satisfy the following expression (5) 8°???20°??(1) 5°???35°??(2) 15°??+??50°??(3) 1.5???r/???4.5??(4) (d/d0)/(0.75+0.025?)?D2/D1??(5) In the expression (4), ?r=1n(2t/d0) and ??=1n{2(d?t)/d0}.

Abstract: A method of manufacturing a seamless tube by the invention can duly control the rotary forging effect without miss-rolling such as defective onset engagement with rolls by satisfying either of (1)–(3) formulas below, dependent on a given range of roll diameter ratio Dg/D1, prevent the occurence of internal surface flaws at the top of the work material attributable to deteriorated hot workability, and further prevent the occurrence of said flaws over the remaining length without altering parameters for piercing-rolling process. Thus, the invention can be widely utilized as an excellent manufacturing method for said tube: in case of Dg/D1<1.1, 23?N/(Df/100)?40,??(1) in case of 1.1?Dg/D1<1.5, 20?N/(Df/100)?44,??(2) in case of 1.5?Dg/D1?1.8, 20?N/(Df/100)?48.

Abstract: The present invention relates to a making method for a seamless metallic tube with a tilting roll type piercing rolling mill (piercer). According to the making method for a seamless metallic tube of the present invention, the rotary forging effect and the circumferential shearing strain can be significantly suppressed without generating uncompleted engagement of a billet. Accordingly, a product having reduced inside defects and excellent inside quality can be produced in high productivity. Further, by strengthening a plug nose rolling portion, a sharpened plug nose is obtained and an engagement limit can be increased. Additionally, a product further excellent in the inside quality can be efficiently produced. Accordingly, the present invention can be applied to wide fields of the piercing rolling of the seamless metallic tube.

Abstract: A 2-roll piercing mill for producing hollow blocks from a rolled material comprising high alloy steels has guide tools for the rolled material. The guide tools are arranged for closing a reforming zone of the piercing mill transversely with respect to the rolling axis as the hollow block is pierced. In this arrangement, each of the guide tools includes a base body made of a carrier material and a working face made of a material that has antiadhesive properties with respect to high alloy steels and high hot strength. Prior to the piercing operation, the temperature of either the working face or the entire guide tool is raised above room temperature to avoid high thermal stresses.

Abstract: A piercer roll exchanging apparatus for use in a vertical piercing mill, as well as a piercer roll exchange method for use with the apparatus, which can automate the exchange of piercer rolls and which are suitable for flexible manufacture of small quantities of seamless steel tubes of a variety of sizes. The apparatus comprises a traveling carrier car capable of moving while carrying upper and lower cradles thereon, and a cradle shifter mounted on the traveling carrier car. The cradle shifter shifts the upper and lower cradles from a traveling end position to the interior of a piercing mill body. The cradle shifter includes a spacer clamp for clamping a cradle-to-cradle spacer and for adjusting the vertical position of the spacer, as well as a lower cradle clamp. According to the present invention, automation of piercer roll exchange work and shortening of the exchange time can be attained by means of a simple structure and without deterioration of workability.

Abstract: A flow-forming device includes a forming device having a cage in which a plurality of rolling members are rotatably arranged in ring-like manner about a rotation axis. A spinning chuck is configured to hold a blank so as to be axially displaceable relative to the forming device. A drive is provided for rotating the blank relative to said forming device. A method for flow-forming includes rotating at least one of the blank and the rolling member about a rotation axis and flow-forming the blank through contact with a plurality of rolling members which are arranged in a ring-like manner around the rotation axis and mounted in rotary manner in a cage.

Abstract: This invention provide a plug and a mandrel bar for use in rolling a seamless steel pipe of which life can be substantially improved more than that of the prior art under a severe condition of use always exposed to a high temperature and high load. The entire plug or the mandrel bar or at least the surface layer of the extremity end and the work section of it is made of ceramics. In addition, this invention provides a method for manufacturing a seamless steel pipe using such a plug or mandrel bar as described above.

Abstract: A method of producing a cylindrical shell in which a billet of circular, transverse cross-section is provided with of first and second sections formed of steel and a liner insert material, respectively. The first section has an end portion and a recess defined within the end portion. The second section is shaped to nest within the recess of the end portion of the first section. The billet is extruded into a cylindrical shell by a billet piercing operation so that the first section produces an outer cylindrical form and the second section produces a liner insert for the cylindrical form. The recess and therefore the second section (forming the liner insert) can be a frustum of a cone. The material for the liner insert may be a corrosion resistant nickel or nickel alloy, Hastalloy C-22, tantalum, titanium, gold or platinum.

Abstract: A process for producing a hollow billet for producing tubing for antifriction bearings includes massively reducing a bloom in a three-roll rotary piercing mill and subsequently piercing the reduced bloom in a three-roll rotary piercing mill. The reducing and piercing may be performed in one-pass through the three-roll rotary piercing mill. The reducing and piercing steps may also be performed in separate passes through the same mill or through two separate mills.

Abstract: A method for manufacturing a seamless pipe, comprises:preparing a billet made of an alloy steel or an alloy;joining a steel plate to an end surface at which piercing of the billet is commenced;preparing a piercing plug made of Mo, a Mo alloy or a heat-resisting steel;hot-piercing the billet by using the piercing plug to produce a hollow shell; androlling the hollow shell to produce a seamless pipe.

Abstract: A method and a device for producing a hollow body from solid round steel that has been heated to shaping temperature by piercing in an inclined rolling mill using pass-closing guide elements. For this purpose, prior to the commencement of piercing, the clear distance between the pass-closing guide elements is reduced in comparison to that of the stationary rolling phase and, after initial rolling, the distance is adjusted to the customary value for the stationary phase. The changes in distance are effected automatically through the balancing of the forces acting on the pass-closing guide elements during the shaping of the round steel and the closing forces which keep the pass opening dimension small.

Abstract: A lubricant is provided for use in hot working such as cross-roll rolling of a seamless steel pipe. It effectively reduces the friction coefficient between the working tools and the material under the hot work, thus extending the lives of the tools. The lubricant contains: (A) from about 10 to about 60 wt % of alkali silicate; (B) from about 1 to about 20 wt % of silane coupling agent; (C) from about 0.1 to about 5.0 wt % of at least one kind of alkali compound selected from a group consisting of an alkali hydroxide, an alkali carbonate, an alkali borate and an alkali salt of mineral acid; and (D) from about 30 to about 70 wt % of water. Alternatively, the lubricant contains: (A) from about 10 to about 60 wt % of alkali silicate; (B) from about 1 to about 20 wt % of silane coupling agent; (C) from about 0.1 to about 5.