Abstract: A seamless steel tubular product is produced by hot-piercing an alloy-steel billet with a piercing plug to produce a hollow shell and then rolling the hollow shell. Prior to the hot-piercing, a steel sheet is joined to an end surface of the billet into which the plug is to be driven, such that the steel plate may not project beyond the periphery of the billet, the steel plate having a surface area (C) satisfying the equation:S.times.0.2.ltoreq.C.ltoreq.S.times.1.2where, S is represented (plug bottom radius).sup.2 .times.3.14.

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 piercing and rolling method involves the use of a piercer provided with cone-shaped main rolls and disk rolls. When a piercing and rolling operation is performed at an expansion ratio of 1.15 or more, the following relations (1), (2), (3), (4), and (5) are satisfied:3.ltoreq.D1/d.ltoreq.7 (1)9.ltoreq.D2/d.ltoreq.16 (2)2<D2/D1.ltoreq.3 (3)2.5.degree..ltoreq..theta.1.ltoreq.4.5.degree. (4),and3.degree. .ltoreq..theta.2.ltoreq.6.5.degree. (5).wherein D1: diameter of the gorge portion of a main roll; D2: diameter at the grooved portion of a disk roll; d: outer diameter of a billet; .theta. 1: inlet face angle of a main roll, and .theta. 2: outlet face angle of a main roll. The apparatus of the present invention is designed so that D1 is between 510 and 2000 mm inclusive and D2 is between 1,530 and 4,000 mm inclusive, and that the above-described relations (3), (4), and (5) are satisfied.

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: A method of manufacturing hollow steel bars comprising the steps of preparing a hollow billet with the dimensions meeting a condition expressed by the following formula (1) by piercing a steel billet with a piercer after heating, inserting a mandrel as an inner surface sizing tool into a hollow billet, and then rolling the hollow billet on a cross-rolling mill having three rolls arranged around a pass line to provide plastic working for reduction of the outside diameter and adjustment of the wall thickness of the hollow billet so as to meet a condition expressed by the following formula (2), and a manufacturing apparatus comprising an electric resistance heating unit, the piercer, and the cross-rolling mill, whereint.sub.0 /d.sub.0 >0.1 (1)Rt<0.55Rd (2)wheret.sub.0 =wall thickness of hollow billet before cross rollingd.sub.0 =outside diameter of hollow billet before cross rollingRt=wall thickness reduction (%), Rt=(t.sub.0 -t.sub.1)/t0.times.100Rd=outside diameter reduction (%), Rd=(d.sub.0 -d.sub.1)/d.

Abstract: A method for manufacturing seamless steel tubes by the Mannnesmann tube making process wherein a billet is passed through a piercer and the center of the billet is pierced through to obtain a hollow shell. A pair of disk rolls are disposed to incline by a skew angle .delta. with respect to a pass line toward cone-type main roll located at the entry side, where a material to be rolled enters into the disk roll sliding face, thereby to become unparallel with the outlet face angle of the main roll, while the skew angle .delta. is set to satisfy the following conditions related to the skew angle .delta., the inlet face angle .theta.1 and the outlet face angle .theta.2 of the main roll, thereby to obtain expansion ratio of outer diameter of 1.15 or higher value..theta.2+2.degree.<.delta.<9.degree., .delta.+.theta.1<12.degree.

Abstract: A two-high cross rolling mill with driven rolls situated one above the other and a pair of rotatably driven guide disks which are supported in rockers which are swivelable around vertical axles and can be adjusted transversely to the swivel axis of the rockers. To optimize the adjusting time and adjusting accuracy, each of the two bearing members of each guide disk is arranged in a vertically adjustable chock so as to be swivelable around a horizontal axis extending transversely to the rolling direction. Each chock is fastened in turn in a clampable manner in a bearing slide which is adjustable in the direction of these swivel axes in horizontal planes and arranged in each instance in fitted guides which are guided in the rockers so as to be displaceable parallel to the rolling direction independently from one another.

Abstract: An inclined-rolling apparatus for piercing and rolling a tube material by the use of a pair of piercing rolls and a pair of disk rolls, wherein rolling operation is executed with the disk rolls being positioned such that a skew angle opposite to the revolving direction of the tube material is added to the outlet sides thereof and their shaft center lines are inclined. In order to get rid of the interference between the piercing rolls and the disk rolls, there is provided a circular groove at the periphery of a side face of each disk roll.

Abstract: A tube making mill setup includes an induction heater for a billet, with means to transfer the heated billet directly to a piercing machine. The piercing machine includes main driving and gripping rolls on skewed axes and which drive the billet onto a piercing point. Upper and lower control rolls have axes parallel to the direction of billet drive through the machine. Internal cooling of the control rolls and the piercing point is provided by circulating cooling water through them. The piercing point is at the distal end of a mandrel which is swingable through an arc to place the formed tube on a take-away carriage.

Abstract: A vertical piercer/elongator mill includes a mill housing having a base, an open top and an open interior defined by a plurality of vertically extending mill posts and interconnecting side portions. A cylindrically shaped bottom cradle supports a rotatable bottom roll and is fitted in the mill housing through the open top thereof to assume an operable position within the open interior of the housing. A cylindrically shaped top cradle supports a rotatable top roll and is also received within the open interior of the mill housing through the open top of the housing. Vertical adjustment apparatus in the form of screw jacks and balance cylinders are associated with the upper and lower cradles to provide vertical movement of the cradles within the mill housing to establish a selected rolling gorge.

Abstract: In an improved process for hot-rolling of seamless tubes with preliminary diameter reduction of the semifinished products (axially pierced round blanks), the coreless reduction step (without mandrel) occurs immediately before the step of continuous rolling on a mandrel and practically at the same time of driving the mandrel into the pierced blank, without interferences therebetween. The apparatus carrying out this operation is positioned immediately upstream of the continuous mill with mandrel, so as to form with this a single unit on the same line, thus reducing the need for room, the operation time and consequently the blank cooling before rolling, whereby the last stand of the rolling mill is reached at a sufficient temperature for rolling without any need of intermediate heating steps.

Abstract: A plug for manufacturing a seamless steel pipe is disclosed. The plug includes the surface layer made of molybdenum or molybdenum base alloy coming in contact with a workpiece to be drilled and the core covered with the surface layer. The surface of the core being in contact with the surface layer is formed uneven. According to the invention, the surface layer and the core are strongly joined together, and the life of the plug is elongated.

Abstract: A method of manufacturing a seamless tube formed of a titanium material, such as pure titanium or titanium alloys, by the use of the Mannesmann's method. At first, an ingot formed of the titanium material is processed under the conditions that a heating temperature is 850.degree. to 1,250.degree. C., the final temperature being 600.degree. to 1,100.degree. C., and a working degree being 50% or more so as to be turned into a solid billet. The resulting solid billet is subjected to a piercing within a temperature range of .beta. transus -100.degree. to 1,250.degree. C. so as to be turned into a hollow piece. In this piercing process, inclined rolls of a piercer are descaled. The resulting hollow piece is, in case of need, regulated a size thereof by elongating so as to be turned into a hollow shell. Subsequently, the resulting hollow shell is subjected to a reducing step (reducing conditions: temperature at an inlet side of the mill is 600.degree. to 1,100.degree. C.

Abstract: A method of manufacturing a metallic tube with a spiral fin for use as a heat transfer tube of a heat exchanger and the like. A solid metallic bar or metallic elementary hollow bar provided with a small hole is supplied to an inclined rolling mill having a plurality of rolls provided with a plurality of annular grooves formed on an outer circumferential surface thereof, and the solid metallic bar or metallic elementary hollow bar is worked into a pierced hollow bar by piercing rolling by means of a piercing plug and at the same time a fin is formed on an outer circumferential surface of the pierced hollow bar to integrate the fin with a body of the tube. Accordingly, the piercing rolling and the formation of the fin on the outer circumferential surface of the tube can be carried out at the same time, so that the manufacturing process can be remarkably shortened and the productivity can be high.

Abstract: Mandrel rod (1) for pipe rolling mills, in which hollow billet (5) is rolled on mandrel rod (1), consists of two pipes (2, 3) lying inside one another. Annular gap (4) between pipes (2, 3) is filled with a thermosetting plastic, whose coefficient of expansion is selected large enough so that the thermosetting plastic completely fills annular gap (4), even with temperature differences, between pipes (2, 3).

Abstract: Ingots hot from rolling are pierced to form a hollow ingot by means of an internal tool of a press or skew-rolling line, and are subsequently elongated to form a tubular bloom by a stretching unit provided with a mandrel rod, and are finally finish-rolled. When inserting or withdrawing the internal tool into or out of the hollow ingot or the mandrel rod into or out of the tubular bloom, inert gas is introduced into the freed interior space in order to prevent scaling of the interior wall of the tubular bloom.

Abstract: A method of manufacturing a metallic tube with a spiral fin for use as a heat transfer tube of a heat exchanger and the like. A solid metallic bar or metallic elementary hollow bar provided with a small hole is supplied to an inclined rolling mill having a plurality of rolls provided with a plurality of annular grooves formed on an outer circumferential surface thereof, and the solid metallic bar or metallic elementary hollow bar is worked into a pierced hollow bar by piercing rolling by means of a piercing plug and at the same time a fin is formed on an outer circumferential surface of the pierced hollow bar to integrate the fin with a body of the tube. Accordingly, the piercing rolling and the formation of the fin on the outer circumferential surface of the tube can be carried out at the same time, so that the manufacturing process can be remarkably shortened and the productivity can be high.

Abstract: Seamless tubing and pipes are made from solid rounds with a diameter not exceeding 0.8 of the diameter of the tubing or pipe to be made; the method includes the steps of piercing the solid with a mandrel such that a conical widening angle at the end of piercing has a particular value; a smoothing step is provided downstream from the piercing also with a particular cone angle; and between the piercing and the smoothing of the now pierced hollow is widened under reduction of the wall thickness at a conical angle of widening that is larger (blunter) than the widening angle of piercing and the particular cone angle.

Abstract: In a method of manufacturing seamless tubes according to the present invention, piercing from a solid billet can be accomplished through one pass by means of a piercing mill ao the present invention, piercing from a solid billet can be accomplished through one pass by means of a piercing mill at the piercing ratio above 4.0 or the expansion ratio above 1.15, or the wall thickness/outside diameter ratio below 6.5%, and the piercing mill having cone-shaped rolls is used with its feed angle .beta. and cross angle .gamma. satisfying the following relations,8.degree..ltoreq..beta..ltoreq.20.degree.5.degree..ltoreq..gamma..ltoreq.35.degree.15.degree..ltoreq..beta.+.gamma..ltoreq.50.degree.and the solid billet diameter d.sub.o, outside diameter d and wall thickness t of a hollow shell after piercing satisfying a prescribed condition for realization, thereby manufacturing equipments can be largely simplified.

Abstract: A pierced hollow rolled by obliquely positioned conical or barrel-shaped rolls, is held against excessive ovality by driven guide sheaves or disks acting in combination with guide bars downstream for controlling the rate of radial widening of the hollow. Oblique positions of the axes of the disks permits them to be of larger diameter.

Abstract: This invention concerns a process and an arrangement for the production of seamless tube. An ingot heated to the rolling temperature is pierced in a skew-rolling stand to form a hollow ingot, is later stretched into a tube bloom and is rolled out into a finished tube. In order to improve this familiar process, it is proposed to conduct the stretching immediately after the piercing in the same heat as the latter, in which case the rolled goods is stretched in the same skew-rolling stand, but with a passage direction that is opposite to that of piercing. An arrangement with which this process according to the invention can be implemented is also proposed.

Abstract: A method of controlling the operation of a cross helical rolling mill. The cross helical rolling mill has a pair of work rolls arranged at respective predetermined lead angles, and a pair of power-driven drive roller shoes arranged obliquely at predetermined lead angles on both sides of the rolling region formed between both work rolls. The method comprises controlling the rotation speed of each of the drive roller shoes in synchronism with the speed of rotation of the rolled material such that the difference in the peripheral speed between each of the drive roller shoe and the rolled material falls within a predetermined range, and, simultaneously with the control of the speed, controlling the driving torque applied to each of the drive roller shoes.

Abstract: An apparatus for delivery and removal of mandrel rods for use with rolling mills. A plurality of rocking levers are arranged one behind the other in the direction of rolling and are pivotable into upper and lower positions. Free ends of the levers are provided receivers for receiving the mandrel rod. The pivot or rocking levers are two-armed angle levers which are slidably mounted in two different positions such that in the first position the receivers on the angle levers are maintained in the vertical projection through the rolling axis and in the other position are offset from such vertical projection.

Abstract: The disclosure is directed to a process and a mill installation for the production of seamless tubes of high quality, in production mills having relatively modest production requirements. The mill installation comprises a cross roll piercing mill for piercing and initially elongating a solid cylindrical billet. Preferably, but not in all cases, the cross roll piercer is followed by a second cross roll "piercer" which functions purely as an elongator, and which functions to substantially elongate the pierced billet, typically in conjunction with an increase in O.D. and reduction in wall thickness. As a key feature, the pierced billet, previously processed by either one or two cross roll piercer/elongators, is thereafter further elongated by means of a Diescher-type elongator, and most particularly a novel form of such Diescher type elongator incorporating a restrained mandrel bar feature.

Abstract: A process and apparatus for the production of seamless tubing incorporating a push bench is provided in which ingots are pierced in the longitudinal direction by diagonal rolls over the stopper rods of a piercing mill to provide pierced ingots having one end with a wall thickening which protrudes outwardly or inwardly, then the wall thickening ends reshaped to provide a partially closed end and finally the pierced ingots are forced through the roll passes of a push bench by mandrel rods engaging the partially closed end so that the ingots are formed into a tube bloom.

Abstract: In a rolling mill plant for the manufacture of seamless tubes, a piercing mill (2), a planetary skew rolling mill (15) and a sizing or stretch-reducing rolling mill (18) are arranged one after the other. In order to improve the output and the quality of the products of plant of this kind, it is proposed not to withdraw the shaft rods (11) used during the piercing operation in the mill (2), but also to use them as internal tools in the planetary skew rolling mill (15). The shaft rods can then remain at the entry end upstream of the planetary skew rolling mill (15) from where they can be returned to the piercing mill (2). Alternatively (FIGS. 2 and 4) they can also pass through the planetary skew rolling mill and be returned from the delivery end thereof to the piercing mill. The insertion, hitherto required, of rods into the hollow ingots before entering the planetary skew rolling mill is not required. The heavy scaling of the surface of the bore in the hollow ingot thereby occurring is avoided.

Abstract: Apparatus is provided for supporting the mandrel back-up bar of a press-piercing rolling mill. The apparatus comprises a plurality of constraining elements supported by a base in two lines disposed parallel to and symmetrically with respect to the rolling and piercing axis of the rolling mill. All the constraining elements of each line are mounted on a single beam which is supported on horizontal guides perpendicular to the rolling axis and adjustable in position on the guides. This arrangement facilitates the simultaneous adjustment of all the constraining elements making up a line.

Abstract: The invention relates to a method of rotary piercing in seamless tube manufacturing under a rotary piercing process, such as Mannesmann mandrel mill process. Rotary piercing operation is carried out by employing a rotary piercing mill having a pair of cone-shaped main rolls adapted to cooperate with a plug for rotary piercing and disc rolls disposed in opposed relation between the pair of main rolls and adapted to press hollow shell on the surface thereof. In this method of rotary piercing, the main rolls have feed and cross angles designed to meet certain conditions individually and in combination. The method makes it possible to carry out rotary piercing of less hot workable and/or extremely hard-to-work materials, that is, high-alloy steel billets, without surface torsional deformation and circumferential shear deformation. Thus, it is possible to manufacture high quality tubes of high-alloy steels free from outside seams and inside bore defects.

Abstract: The compound tool is made from a powder-metallurgically-prepared portion, establishing the wear-resisting zones onto which a carrier body is cast from steel.

Abstract: The present invention relates to manufacturing process of seamless metal tubes by elongating mill such as Mannesmann mandrel mill. Shells are subjected to rolling operation with main object of wall thickness equalization by means of a rotary mill having 3 rolls without any internal tools such as mandrel bar or plug. This process improves wall eccentricity and enables to decrease the number of billets as materials for tube making.

Abstract: In a rolling mill having a perforating head supported on a bar which is rotatable and longitudinally displaceable, the bar is supported on a carriage by way of a gripper fixed to the carriage and engaging a recess in the bar with sufficient radial play to allow rotation of the bar. The recess also affords axial clearance so that the rolling reaction on the perforating head displaces the rear end of the bar into abutment with a planar end contact face of a rotating bearing. The abutment of the end of the bar against the contact face allows the bar to be ejected laterally without previous axial disengagement of the bar from the bearing.

Abstract: A plug for use in a piercing and elongating mill characterizing in that an adherent durable surface layer consisting essentially of iron oxides, i.e. FeO, Fe.sub.3 O.sub.4, Fe.sub.2 O.sub.3 or mixtures thereof is formed on the surface of the plug by spraying said molten iron oxide powder onto the plug surface to form said layer. The powder may also contain oxides of chromium, nickel, cobalt, copper, manganese and alloys thereof. The plug is preferably coated with a layer of nickel aluminum before the iron oxide powder is sprayed thereon.

Abstract: Two water tanks, one behind the other, are disposed adjacent to the rolling gap for a piercing mill; the rolled seamless tube on a mandrel rod passes through both tanks during rolling. The tank closest to the gap contains also a mandrel holder, and following rolling the mandrel is retracted into that tank; this tank, but not the other one, is emptied and the mandrel on the rod is exchanged. The tank is refilled and the next billet can be rolled. Nozzles are provided to prevent water from escaping through openings in tank walls for the tube.

Abstract: A solid square cross-section bloom or billet is pierced to form a hollow cylindrical piece with a closed end, using a combination of a mandrel carrying a plug or piercing point at its leading end and a set of rolls. The closed-end cylindrical workpiece and the piercing mandrel together, at the completion of piercing, are fed into a rotary elongating mill, with the closed end of the workpiece foremost. Rotary elongation is performed on the workpiece while pushing the mandrel until the plug has at least passed the point at which the closed end of the workpiece clears the delivery end of the elongation rolls.

Abstract: The present invention is directed to a device for inserting and thrusting a bar into a double rolling pressure piercing mill (PPM) machine comprises a drum-shaped bedplate coaxially keyed to a motor-driven shaft having its axis of rotation parallel to the PPM's rolling axis, a first and a second thrust means on the drum-shaped bedplate having acting lines (R R.sub.1) parallel to the PPM's rolling axis and circumferentially spaced from each other by a predetermined center angle, a motor for angularly moving the drum-shaped bedplate from a position in which the line R coincides with the rolling axis to a second position in which the line R.sub.1 coincides with said rolling axis and vice-versa.

Abstract: Rolling mill for forming seamless pipes from round billets, comprising a rotary piercing mill or a punch press for shaping billets into hollow blocks, a cross conveyor leading to a planetary rolling mill for the rolling of the hollow blocks on a mandrel into seamless pipe, followed by stretch-reducing rolling mill for rolling the seamless pipes into a finished product.

Abstract: A device for controlling the speed of a mandrel in a continuous retained-mandrel rolling mill, such device comprising a rod having a double rack provided at one end with a means for removably securing an end of a mandrel and a number of pinions engaging the rack on the rod, each pinion being driven in rotation by a corresponding motor-driven shaft which, via respective clutches is connected to a motor and speed-reducing group provided with a brake for each motor-driven shaft. Further, the device includes a second set of pinions engaging the rack on the rod, each pinion being driven in rotation by a corresponding motor and speed-reducing group provided with a brake.

Abstract: An arrangement for securing and easily releasing a mandrel from a mandrel rod upon their advancement and return movements during the piercing operation of a seamless tube. Between the mandrel and rod is an intermediate piece having one or more openings for receiving a hook with a nose extending into an opening of the mandrel. The hook is biased into position by a spring mounted around its one end and at its other end beneath a nose is a tapered surface for contacting a corresponding surface of the mandrel to pivot the hook away from the interior of the mandrel to release the mandrel from the intermediate piece and mandrel rod.

Abstract: The disclosure of the present invention concerns a piercing rolling mill with a mandrel changing device which has at least two groove-like recesses which can be positioned alternately in the rolling line in order to hold the mandrels, and a retractable mandrel stripper, and where the mandrel rod carries at its front end a pin on which the mandrel is attached in such a way that it is detachable against the effect of expanding springs or similar means.

Abstract: A method of producing a cylindrical metallic tubular body in a press roll piercing mill. The method involves applying a pressing force to a polygonal metal billet in the axial direction thereof while guiding the billet by means of a guide during its advance, rolling corner portions of the billet to a certain degree with a pair of rolling rolls having semicircular grooves disposed above and below the billet prior to the contacting of a plug with the center of the front end surface of the billet, and successively piercing the billet by means of the plug while the billet is rolled, the tip portion the plug being retained on the pass center line by the rolling rolls.

Abstract: A pipe reeling machine guide for guiding and burnishing an external surface of a pipe having a work contact surface of a composition consisting essentially, in percent by weight, of: 0.70-0.90 carbon, up to 1.75 manganese, 0.08 max. phosphorus, 0.08 max. sulfur, 0.5-1.75 silicon, 8-12.0 nickel, 23-27 choromium, and the balance being essentially iron with residual impurities.

Abstract: The plug is assembled from three parts held against the mandrel by a tie rod which is screwed into the front and guiding part. A spacer is keyed to the latter part as well as to the tie rod, whereby tie rod keying is provided though flat surface portions interrupting the cylindrical surface portions of the spacer bore and the tie rod, while the guiding part and spacer are mutually keyed through axially aligned square portions and a clip thereon.

Abstract: The disclosure is directed to improvement in piercing and reeling mills, to facilitate the changing of mandrel plugs and mill shoes. In piercing and reeling operations, mandrel plugs are supported at the ends of elongated mandrel bars, and workpieces are driven over the mandrel plugs while being rotated, to effect piercing and enlarging, in the case of piercing mills, and to achieve roundness, in the case of reeling mills. In each case, after processing a finite length of tubing, and while the workpiece remains on the mandrel, the mandrel is retracted, first stripping off the just-used mandrel plug, and then withdrawing the mandrel from the processed workpiece. A multi-position magazine is provided for retaining a circulating supply of mandrel plugs such that, after each operation, the used mandrel plug may be returned to the magazine for cooling, and a new plug may be brought quickly into working position ready for the next operation.

Abstract: A method for changing the plug in a mandrel in which the plug is attached to the mandrel by a detachable interlocking mechanism. The plug is maintained fixed to the mandrel during the displacement of the latter through the blank following piercing and the plug is detached from the mandrel to the rear of the piercing mill towards the end of the rearward displacement of the mandrel. A new plug is then fitted on to the mandrel during the subsequent displacement of the mandrel in the direction of the piercing mill.

Abstract: The disclosure generally relates to a positive drive hose reel apparatus for a cooling system mounted on the linearly movable thrust block of a piercing or reeling mill. The thrust block means is adapted to move along a path between a working position and a retracted position and includes a rotatably mounted hose reel apparatus to support a flexible hose. The hose interconnects a remote water supply with the cooling system of the thrust block. A drive cable extends between and is secured at points adjacent the working position and retracted position and is partially wrapped around the hose reel apparatus, whereby the linear movement of the thrust block will impart positive rotational movement to the hose reel apparatus and thereby coil and uncoil the hose, as needed as the thrust block moves at high speed back and forth along the path.

Abstract: The rolling mill plug assembly comprises a guide plug and a working plug joined together in interlocking relationship. The working plug includes a female connection formed by a socket recess in one end. Two opposing flanges extend over the recess and are spaced apart by a central opening and opposing slots in registry with the recess. The guide plug includes a male connection comprised of a neck extending outward from one end of the guide plug which terminates in two opposingly extending lugs which are adapted to pass through the slots and into the recess in the working plug. Rotating the guide plug positions the lugs under the flanges and locks the guide plug in place within the recess of the working plug. A key assembly can be employed with the two plugs to maintain them in interlocking relationship.

Abstract: A device for use in piercing and plugging mills, comprising a rod with a plug and a gear, for keeping the rod from longitudinal displacements under the effect of the load arising during the piercing or plugging. The gear includes a fixed thrust bearing accommodating a revolving casing through which passes the rod that reciprocates in operation. A part of the internal surface of the revolving casing forms a working cone that faces the plug with its base. The gear also includes a lock to fix the rod when piercing or plugging a billet, and preferably mounted on the rod, and a drive for carrying the rod with the plug. The lock mounts a spring-biased cone positively encompassed round the circumference with radially floating cams. Before piercing, the spring-biased cone is slightly drawn off by the spring from the cams so that the latter can enter the lock which is then able to enter the casing.