Abstract: An exemplary embodiment of the invention provides a method for producing an ultra thin wall metallic tube by cold working method with significant wall thickness reduction. In a method for producing the metallic tube with a cold pilger mill according to the invention, cold rolling is performed while tube diameters are being expanded using rolls having tapered groove dies whose calibers increase from an engaging entry side toward a finishing exit side. In a method for producing the metallic tube with a drawing machine according to the invention, cold drawing is performed while the tube diameters are being expanded using a solid die whose calibers increase from an engaging entry side toward a finishing exit side and a plug of a tapered mandrel bar whose diameters increase from an entry side of the die toward an exit side. In the metallic tube producing method, a maximum diameter of the plug or tapered mandrel bar may be larger than an outside diameter of the mother tube.

Abstract: In applying a non-graphite-based lubricant composed of, by mass %, 10 to 70% of an oxide-based lamellar compound and 30 to 90% of boric acid onto a mandrel bar, the lubricant film thickness is set from a predetermined master curve for the lubricant film thickness corresponding to an amount of mica. This stably produces a seamless steel pipe of high quality, while preventing seizing marks and internal flaws.

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 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: The object of the present invention is to provide a mandrel mill capable of producing a seamless pipe without flaws such as necking. The mandrel mill of the present invention includes a plurality of consecutively provided grooved-roll stands and a mandrel bar 3 provided in a roll groove array formed by the grooved-roll stands so as to continuously elongate a hollow shell 2. Roll grooves 4 of at least a first stand and a second stand are arranged so as to satisfy conditions represented by the following formulas (1) to (4): b?10a+1.5 ??(1) b?10a?0.2 ??(2) b??a+1.5 ??(3) b??a+1.15 ??(4) wherein a=S/R1, b=C/(R1?S).

Abstract: The object of the present invention is to provide a mandrel mill capable of producing a seamless pipe without flaws such as necking. The mandrel mill of the present invention includes a plurality of consecutively provided grooved-roll stands and a mandrel bar 3 provided in a roll groove array formed by the grooved-roll stands so as to continuously elongate a hollow shell 2. Roll grooves 4 of at least a first stand and a second stand are arranged so as to satisfy conditions represented by the following formulas (1) to (4): b?10a+1.5??(1) b?10a?0.2??(2) b??a+1.5??(3) b??a+1.15??(4) wherein a=S/R1, b=C/(R1?S).

Abstract: The present invention provides an application method of a Cr-plated mandrel bar repeatedly used in mandrel mill rolling by the Mannesmann tube making process. A regeneration treatment is performed to use the mandrel bar again as a tool of like size when an opening width H of a surface defect generated on the mandrel bar by its use in the mandrel mill rolling is not less than 1.5 mm and a depth of the surface defect is in the range of 0.3 mm to less than 2.0 mm. Alternatively, a downsizing treatment is performed to use the mandrel bar again as a tool of a smaller size when the depth of the surface defect generated on the mandrel bar by its use in the mandrel mill rolling is not less than 2.0 mm. The regeneration treatment or downsizing treatment is performed according to conditions or a configuration of the surface defect to achieve repeated application to the mandrel mill rolling, allowing life-extension of the mandrel bar and improvement of cost performance thereof.

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: An aspect of the present invention provides a method for producing an ultra thin wall metallic tube by a cold rolling method with significant wall thickness reduction. In a method for producing the metallic tube with a cold pilger mill, a wall thickness is reduced to perform elongation while a wall thickness center diameter is expanded using a pair of rolls, which has a tapered groove die whose diameter is gradually expanded or reduced from an engaging inlet side of the roll toward a finishing outlet side thereof, and a tapered mandrel bar, whose diameter is gradually expanded from an engaging inlet side of the tapered mandrel bar toward a finishing outlet side thereof.

Abstract: A process for stainless-steel pipe production which comprises piercing rolling a raw material stainless steel containing, by mass, Cr: 10-30%, to give a hollow shell, elongating rolling the hollow shell using a mandrel bar, together with a graphite-free lubricant, to give a finishing rolling blank pipe and heating the blank pipe in a reheating furnace and subjecting the same to finishing rolling by sizing rolling to produce a hot-finished pipe, and then subjecting this pipe as a mother pipe to cold working to produce a stainless-steel pipe. In the reheating furnace, the finishing rolling blank pipe is heated to 1000° C. or more and subjected to heating in which an oxidizing gas is blown into the pipe inside, whereby a stainless-steel pipe which is inhibited from forming a carburized layer in the pipe inner surface can be produced. When the finishing rolling by sizing rolling to give a cold working mother pipe is carried out by stretch reducer rolling at 860-1050° C.

Abstract: An exemplary embodiment of the invention provides a method for producing an ultra thin wall metallic tube by cold working method with significant wall thickness reduction. In a method for producing the metallic tube with a cold pilger mill according to the invention, cold rolling is performed while tube diameters are being expanded using rolls having tapered groove dies whose calibers increase from an engaging entry side toward a finishing exit side. In a method for producing the metallic tube with a drawing machine according to the invention, cold drawing is performed while the tube diameters are being expanded using a solid die whose calibers increase from an engaging entry side toward a finishing exit side and a plug of a tapered mandrel bar whose diameters increase from an entry side of the die toward an exit side. In the metallic tube producing method, a maximum diameter of the plug or tapered mandrel bar may be larger than an outside diameter of the mother tube.

Abstract: A mandrel assembly is provided for insertion into a hollow tube to support the interior walls of the tube during bending of the tube in a tube bending apparatus. The mandrel assembly includes at least one mandrel segment that is adapted for positioning within the tube and has an exterior support surface for supporting the interior walls of the tube during bending. The mandrel segment is anchored at a fixed axial location within the tube by an anchoring device that is radially expandable and retractable between an expanded condition in which an anchor shoe is engaged with the interior wall of the tube and a retracted condition in which the anchor shoe is loose within the tube. A mandrel support rod is attached to the anchoring device for inserting and withdrawing the anchoring device into the tube when the anchor shoe is retracted.

Abstract: An exemplary embodiment of the invention provides a method for producing an ultra thin wall metallic tube by cold working method with significant wall thickness reduction. In a method for producing the metallic tube with a cold pilger mill according to the invention, cold rolling is performed while tube diameters are being expanded using rolls having tapered groove dies whose calibers increase from an engaging entry side toward a finishing exit side. In a method for producing the metallic tube with a drawing machine according to the invention, cold drawing is performed while the tube diameters are being expanded using a solid die whose calibers increase from an engaging entry side toward a finishing exit side and a plug of a tapered mandrel bar whose diameters increase from an entry side of the die toward an exit side. In the metallic tube producing method, a maximum diameter of the plug or tapered mandrel bar may be larger than an outside diameter of the mother tube.

Abstract: A process for manufacturing a hollow metal ball bat includes forming a shell into a tubular shape using a pilger mill. The wall thickness of the tube shell is reduced by drawing the tube shell with the draw bench. A handle section and a taper section are created using the pilger mill. The handle is drawn through a draw bench, and the handle and taper sections are swaged.

Abstract: The holder member 4 is rotatably supported at the tip portion 2a of the sliding member 2 placed on the guide face 1a of the guide member 1 arranged fixedly inside the cylinder C. The holder member 4 is inclined when the tip portion 3a of the profiling member 3 is inserted between the holder member 4 and the sliding member 2. Then the tapered end of the processing roller 6 is pushed into the inner peripheral surface of the cylinder where the sliding member 2 and the profiling member 3 move together in the axial direction of the cylinder, thereby to form a linear groove on the inner peripheral surface of the cylinder C.

Abstract: In the cold rolling process by pilger rolling that holds a mandrel between each of paired roll-dies, by optimizing the side relief rate SR and the pass schedule factors such as the Area Rd, ID Rd and the feed rate F of the workpiece material, and further by properly selecting the taper ?1 in the primary deformation zone of mandrel and the taper ?2 in the final size reduction zone thereof, the dimension-related shape characteristics (near-perfect round shape) of the tube inside surface after the final finishing rolling process by pilger rolling can be ascertained to thereby ensure excellent surface property without requiring a new apparatus, and further without causing the decrease of the product yield and/or the increase of the manufacturing costs. Thus, this can be widely applied for producing steam generator tubes which exhibits high S/N ratio in the inner coil eddy current testing.

Abstract: In the cold rolling process by pilger rolling that holds a mandrel between each of paired roll-dies, by optimizing the side relief rate SR and the mandrel factors like the taper ?1 in the primary deformation zone of the mandrel and the taper ?2 in the final size reduction zone thereof, and the feed rate F of the workpiece material, and at the same time by properly adjusting the relationship between the side relief rate SR and the feed rate F, the dimension-related shape characteristics (near-perfect round shape) of the tube inside surface after the final finishing rolling process by pilger rolling can be ascertained to thereby ensure excellent surface property without requiring a new apparatus, and further without causing the decrease of the product yield and/or the increase of the manufacturing costs. Thus, this can be widely applied for producing steam generator tubes which exhibits high S/N ratio in the inner coil eddy current testing.

Abstract: When manufacturing a seamless pipe by carrying out elongation rolling and sizing on a mother tube for forming a seamless pipe, the occurrence of portions of thickness variation in the seamless pipe is suppressed by previously identifying the portions of wall thickness variation where the thickness varies in the circumferential direction of the seamless pipe, and carrying out elongation rolling so that the thickness of the portions of the mother tube corresponding to the portions of wall thickness variation of the seamless pipe are different in thickness at the completion of elongation rolling from that of other portions of the mother tube. As a result, local variations in wall thickness in the circumferential direction of a seamless pipe are prevented.

Abstract: By employing a Cr-plated mandrel bar for producing hot seamless tubes according to the present invention wherein centerline average roughness Ra in axial and circumferential directions as well as maximum depth Rv in axial and circumferential directions is specified and further maximum height Rp in axial and circumferential is specified, surface defects such as seizure unlikely generate in an elongation-rolling process by a mandrel mill so that the service life can be dramatically extended, thereby the remarkable reduction of tool cost can be achieved. Moreover, it contributes greatly to improve the inner surface quality of hot seamless tubes to be rolled by a mandrel mill rolling process. Also, the manufacturing method by the present invention makes it possible to efficiently manufacture Cr-plated mandrel bar for producing hot seamless tubes.

Abstract: A complex Fourier transform is performed on measured values of wall thickness at points in a cross section of a pipe in an axial direction, types of thickness deviation are classified, thickness deviation amount is calculated from the absolute value of the complex Fourier component, the position of a thick or thin portion of thickness deviation is calculated from the phase of the complex Fourier component, and manufacturing conditions of the pipe are adjusted based on these variables. The relationship r·exp(j?) between the thickness deviation amount r and phase ? of a first-order thickness deviation obtained for cross sections in the axial direction is subjected to a complex Fourier transform as a function of pipe longitudinal direction, the thickness deviation is further classified by the frequency of twist of the thickness deviation, and an action is taken to prevent the thickness deviation according to the classified thickness deviation.

Abstract: A method of producing a torque transmission between a driving member and a driven member including the steps of capturing an annular gear within the interior of a hollow cylindrical shell formed of a formable material which is caused to be flow formed around a portion of the exterior of the gear to militate against any relative longitudinal and axial movement between the shell and the gear.

Abstract: In the planetary skew rolling blooms to form seamless metal tubing or pipe the internal tool is retracted at the leading and/or trailing end of the tubular bloom to allow the rolls to seal the end or ends and prevent coolant from entering the rolled tubing or bloom. The internal tool is advanced back into its normal rolling position after the end has passed the rolling location.

Abstract: Disclosed is a producing method which allows low-cost and highly productive production of a seamless tube with a grooved inner surface having a smooth outer surface and an inner surface formed with plural types of grooves such that a protrusion is not formed at the produced seamless tube with a grooved inner surface. The tube is reduced in diameter by using a die and a plug. Then, the outer surface of the tube is pressed against a grooved plug by means of a pair of rolls such that a groove is formed in a portion of the inner surface of the tube. The process flattens the cross-sectional configuration of the tube in the direction in which the tube is pressed with the rolls. Subsequently, a sizing process using a die is performed with respect to the tube such that the tube has a generally circular configuration.

Abstract: A tubular blank (22) is rolled on a mandrel (14) in a pilgrim rolling mill. In a first rolling stage, a first part of the blank (22) is rolled on a first part (18,19) of the mandrel (14), with a reduction of the outside diameter of the blank (22) to the outside diameter of the guide tube and a reduction of the wall thickness of the blank (22) to one of a first wall thickness (e1) and a second wall thickness (e2) exceeding the first wall thickness (e1). The mandrel (14) is advanced in the axial direction. A second part of the blank (22) is rolled on a second part (20,21) of the mandrel spaced from the first part in the axial direction with a reduction of the outside diameter of the blank to the outside diameter of the guide tube and a reduction of the wall thickness of the blank (22) to the other of the first wall thickness (e1) and second wall thickness (e2).

Abstract: The present invention provides methods of forming mud motors. In one method, rollers are urgingly stroked against a tubular member having a mandrel therein that has an outer profile which is the inverse of the desired profile of the stator. In another method, rollers are urged and rotated radially on the tubular member with the mandrel disposed in the tubular member. In yet another method, dies are pressed against the tubular member having a mandrel with a desired outer profile. In another method, a molten metal is deposited over a mandrel with an outer lobed surface that is substantially the inverse of the desired inner profile of the stator housing. The mandrel is then removed, leaving a metallic longitudinal member having an inner profile defined by the outer profile of the mandrel. In each of these methods, the inner surface of the resulting member has the profile defined by the outer profile of the mandrel.

Abstract: A rolling machine for processing a metal container which has a longitudinal seam and is made from a flat metal plate to form a cylindrical body having adjacent or overlapping butt edges securely joined to one another by folding or welding, whereupon a disk-shaped lower bottom and, optionally, a respective upper bottom, is welded or folded to the cylindrical body to form a closed container, or an open-topped container, respectively, is configured as a continuous rolling machine and includes an upper carrier frame; an upper rolling drum rotatably supported in the upper carrier frame; a lower drum stand; and a driven lower rolling drum rotatably mounted in the lower drum stand.

Abstract: A method and apparatus for drawing an elongated stock continuously are disclosed which permit plural types of drawings to be done at a narrower area than in the prior art by a series of automated works and which permits easy adjustment of the distance between a front end position of a plug and an outlet position of a die. A holding member with plural types of dies 18a and 18b mounted at a central position for reciprocation of an elongated stock is held movably. When the elongated stock is to be moved from one side to the opposite side with the dies holding member as the center, it is passed through an elongated stock passing space, not through the dies, while when the elongated stock is to be moved from the opposite side to the one side with the dies holding member as the center, it is passed through one of the plural dies.

Abstract: This invention relates to the plastic metal working, particularly to tube rolling production and can be applied for tube cold pilgering on rolling machines. Tool design for tube cold pilgering, in which, in order to increase accuracy, surface quality, mechanical properties stability and decrease rolled tubes defects, the evolvement of external and profile of internal tooling are executed in the form of unified curve and represent geometrical location of various spline-functions key-points, whereupon along with geometrical parameters of spline-functions calculated curves the authors use factors defining physical-mathematical properties of rolled material and pilgering schemes.

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 method and apparatus for smoothing a thick walled portion of a steel pipe produced by pressure-welding two opposite longitudinal edges of an open pipe with a squeeze roll after being subjected to induction heating. Outer and inner reduction rollers pressure sandwiches the thick walled portion from the outer and inner surfaces of the pipe, a support supports the inner reduction roller to be rotatable and containing a water passage for cooling water, a connecting rod connects the support device to a coupler and contains a further water passage for feeding cooling water to the water passage, and an anchor holds the connecting rod. In the a method of producing steel pipes two opposite longitudinal edges of the open pipe are preformed before being subjected to the induction heating and thereafter a thick walled portion is smoothed by the above-described apparatus.

Abstract: A cold pilger rolling tool for producing internally ribbed tubes uses a cold pilger step rolling process in a rolling stand that is movable back and forth in a direction of rolling and has rolls of a tapered design. The rolls of the stand roll along a material with an alternating direction of rotation. The tool includes a cold pilger rolling mandrel which tapers. The tool further comprises an extension plug mounted coaxially and rotatably at a free end of the cold pilger rolling mandrel and in which a negative of the helical internal ribbing which is to be produced is machined.

Abstract: Process for creation and adjustment, from one moment to the next, of the external force to apply by the feed assembly to the preformed forging in cold rolling mills of the "pilgrim process" type with rollers and mandrel for producing seamless tubes by means of a computer, in accordance with the geometric parameters of the contours of the rollers and of the mandrel and in accordance with the reaction generated during rolling in the roller supports, for lessening the risk of breaking the tube, reducing unit loads and raising productivity.

Abstract: The present invention is of a mandrel bar assembly for a seamless pipe mill. The assembly includes a pair of tooling sections each having a tapered end, a reduced diameter portion axially inward of the tapered end adapted to be gripped by a retaining means of the mill, and a working portion adjacent the reduced diameter portion extending from the reduced diameter portion to the end opposite the tapered portion. The assembly includes a coupling for connecting the tooling sections together end-to-end with the tapered ends facing oppositely outward therefrom. An adapter is provided to cover the reduced diameter portion and provide a working surface thereon of one tooling section that is to be positioned as the lead end into the mill. When one tooling section wears the adapter can be removed and installed on the other tooling section, and the assembly is reversed end-to-end to use the other tooling section as the lead end, extending the useful life of the assembly.

Abstract: A multiple disk clutch includes a clutch drum having an interior surface with a plurality of spline grooves, a servo piston, a clutch plate with splines engaged within the spline grooves, and a cushion plate, with splines engaged within the spline grooves, arranged between the clutch plate and the servo piston. The splines of the clutch plate and those of the cushion plate are engaged within different spline grooves so that the splines of the clutch plates and those of the cushion plate do not contact each other when the clutch is engaged by a load imposed by operation of the piston.

Abstract: Inner or outer cylindrical worked surfaces of powder metal components are bearingized by orbiting tapered rollers against them using a tapered mandrel having points for impacting the rollers against the worked surface.

Abstract: Hollow cylindrical blanks of tubular stock are transformed into finished work pieces (3) in a single work stroke with a profiling tool (7) equipped with profiling rollers (30) in one tool section (8) and a die matrix (15) in another tool section (6). The two tool sections (6, 8) are coaxially movable relative to each other, for example by a press. Each profiling roller in the one tool section is rotatably mounted in a chamber and all rollers (30) are positioned circularly around a central longitudinal tool axis (34) so that a central plane of each roller extends substantially radially relative to the tool axis. The die matrix (15) in the other tool section (6) is supported on a central mandrel or arbor (14) that also supports the blank. The die matrix (15) has in its outer surface a plurality of grooves (15A) and ridges (15B) that cooperate with grooves and ridges in the profiling rollers.

Abstract: Disclosed are a method and apparatus for manufacturing tubes, preferably tubes composed of high-tensile steels or special alloys, using the cold pilger rolling method with two rolling stands which can be moved backward and forward, at least in opposite directions at times and in the rolling direction by means of crank drives. The rolling stands have rollers which are calibrated in a tapering manner and which, driven by toothed racks via cogs, roll over the material to be rolled, with an alternating rotation direction. The majority of the forming work takes place on the first rolling stand and a relatively small portion of the forming work takes place on the second rolling stand and additional smoothing work is carried out.

Abstract: A tool is provided for working a shaped metal tube, such as a square or rectangular metal tube, having a hollow interior and an outer surface to produce an end reduction in the tube. The tool includes a head having a longitudinally extending interior cavity and a plurality of roller cavities, each communicating with the interior cavity. A plurality of grooved rollers are rotatably mounted within the head, one within each of the roller cavities. Each of the grooved rollers has a periphery extending into the interior cavity and configured to engage a portion of the outer surface of the tube to be reduced, such as a corner portion of a square tube. Depending upon the shape of the tube being reduced, the tool may further include a pair of flat-area rollers. The flat-area rollers may be used to engage the relatively long sides of a rectangular tube.

Abstract: Hollow cylindrical blanks of tubular stock are transformed into finished work pieces (3) in a single work stroke with a profiling tool (7) equipped with profiling rollers (30) in one tool section (8) and a die matrix (15) in another tool section (6). The two tool sections (6, 8) are coaxially movable relative to each other, for example by a press. Each profiling roller in the one tool section is rotatably mounted in a chamber and all rollers (30) are positioned circularly around a central longitudinal tool axis (34) so that a central plane of each roller extends substantially radially relative to the tool axis. The die matrix (15) in the other tool section (6) is supported on a central mandrel or arbor (14) that also supports the blank. The die matrix (15) has in its outer surface a plurality of grooves (15A) and ridges (15B) that cooperate with grooves and ridges in the profiling rollers.

Abstract: A gear teeth forming apparatus is used for forming a plurality of gear teeth on an outer circumferential wall of a pressed drum. The apparatus includes a die and a plurality of rotational rollers. A plurality of convex/concave portions are formed in the axial direction on the die. The die has an outer circumferential surface on which the outer circumferential wall of the pressed drum is fitted. Also, the die is movable in the axial direction. A plurality of the rotational rollers are insertable partially into grooves of the die and are rotatable along the grooves.

Abstract: A process for rolling tubes, in which two grooved rolls mounted opposite one another in a roll stand are moved back and forth, i.e., reciprocated, on tube-shaped rolling material, which is arranged on a tapered rolling mandrel supported in the axial direction by a mandrel bar. The rotary-driven rolls have, on their circumferential surfaces, narrowing work grooves matching in shape to the tapered rolling mandrel, which roll down the rolling material on the rolling mandrel. At the ends of the work passes the rolls release the rolling material at the two dead centers of the roll stand path so as to assist in the advancement and rotation of the rolling material. According to the invention, the tube-shaped rolling material and the rolling mandrel are driven asynchronously in the same rotational direction at different rotational speeds.

Abstract: An automobile steering rack manufacturing apparatus has a material clamp for holding a hollow pipe-like rack material that has a solid core bar inserted therein. A forming roll on the apparatus has an outer periphery with rack teeth formed thereon, while a material drive causes a mutual rolling of the material clamp and the forming roll, thereby cutting rack teeth into the material. The clamp moves in the tangential direction of the forming roll orientation, and a tooth depth controller controls the distance between the rack material held in the material clamp, and the forming roll.

Abstract: A gear teeth forming apparatus is used for forming a plurality of gear teeth on an outer circumferential wall of a pressed drum. The apparatus includes a punch and a plurality of rotational rollers. A plurality of convex/concave portions are formed in the axial direction on the punch. The punch has an outer circumferential surface on which the outer circumferential wall of the pressed drum is fitted. Also, the punch is movable in the axial direction. A plurality of the rotational rollers are insertable partially into grooves of the punch and are rotatable along the grooves.

Abstract: A single-piece self-guiding, high integrity high mill plug for producing seamless tubular steel products in rolling mills is provided. The high mill plug is produced from a single a casting having a substantially bullet shape with an opening at each end and a passage therebetween to allow gases which develop during the casting process to escape. By designing the high mill plug to be produced from a single casting with no dead-end cores, the latent surface defects associated with the prior multi-piece casting designs are substantially avoided and the casting used to produce the single-piece self-guiding high mill plug has a very high integrity. The single-piece self-guiding high mill plug substantially improves rolling mill operations for producing seamless tubular steel products by eliminating both time and labor expenses associated with disassembling and reassembling the worn work plug sections as required by the prior art multi-piece high mill plug designs.

Abstract: In a mandrel mill for elongating and rolling a hollow shell, with a mandrel bar inserted, by passing the hollow shell, a four-roll stand for diameter reduction used to reduce only the outer diameter of the hollow shell is disposed as the first stand, a group of two-roll stands for wall thickness reduction used to reduce the wall thickness of the hollow shell is disposed following the four-roll stand, and a four-roll stand for eccentric wall cancellation used to cancel any nonuniform wall thickness in the circumferential direction of the hollow shell is disposed as the final stand. The ratio (D.sub.i /D.sub.m) between inner diameter D.sub.i of the hollow shell on the outlet side of the four-roll stand as the first stand and outer diameter D.sub.m of the mandrel bar is 1.05 or less.

Abstract: In a method and a roll stand for diagonal rolling of medium or thin-walled tube ingots, an inner mandrel rod is held at an inlet side and controllably axially displaceably relative to rolls. In order to avoid a funnel-shaped expansion at the tube ingot end, the rolling product during rolling is rolled in a constriction of the mandrel rod and thereby obtains a thickened wall forming a support of the tube ingot wall against the expansion.

Abstract: A method of making stock for fabricating a hollow metal ball bat, the stock having a barrel section, a handle section and a tapered section connecting the barrel section and handle section. The barrel section has a first inner and outer diameter. The handle section has a second outer and inner diameter. The second outer and inner diameters are smaller than the first outer and inner diameters. The tapered section has a variable inner and outer diameter along its length and a substantially uniform wall thickness.

Abstract: A roll mandrel monitoring device in cold pilger mills with a coil which surrounds the rolled tube concentrically and is arranged on the delivery side after the rolling mill for detecting longitudinal movement of a coil core which is fastened inside the tube to a bar extending between the mandrel and coil coaxially to the tube. In order to achieve faster reaction times and accordingly to stop the rolling mill when the mandrel breaks, the bar is connected with the mandrel rod holding the mandrel so as to penetrate the mandrel concentrically and is constructed in the region of the mandrel as a tension bar which can be pretensioned against the end of the mandrel on the delivery side with the intermediary of an energy accumulator.

Abstract: A mandrel mill for rolling seamless steel tubes includes a plurality of roll stands each having a pair of rolls defining a roll groove therebetween, an axis of the rolls of each roll stand being orthogonal to the axis of the rolls of the adjacent roll stands. The mandrel mill further includes a mandrel bar disposed in the roll grooves configured by the roll stands. The ratio between the radius of curvature of a groove bottom of the groove and a distance between the groove bottom of the roll groove of the first stand ranges from 0.46 to 0.54, and that of the second stand ranges from 0.48 to 0.52.

Abstract: In a method of elongating a metal tube by means of a mandrel mill, a tapered mandrel bar is inserted into a hollow piece and the feeding speed of the mandrel bar is controlled so as to change the length by which the mandrel bar projects beyond the delivery end of the final stand of the mandrel mill at the point of time when the leading end of the hollow shell is gripped by the rolls in the final stand. As a result, the wall thickness of the hollow shell is altered to permit the rolling of hollow shells of many sizes with different wall thicknesses using a single mandrel bar.