Abstract: Method of obtaining hollow forgings by radial forging of solid blanks where generating AA of the surface of solid blank (1) or its edge is oriented longitudinal axis CC of the working surface of forging tool (3) and blank 1 is swaged in a radial direction by at least one pair of forging tools (3) first in one direction with its subsequent rotation around longitudinal axis OO and/or is moved along axis OO, is swaged in another radial direction at defromation rates approximately within 3-8% of the current cross-sectional dimensions of blank (1) with the result that the width of the contact area element is approximately within 0.121-0.124 of said current cross-sectional dimension of blank (1).

Abstract: A method and apparatus for forming a head, having a controlled predetermined shape on an end of an elongate member, such as a wire, which is formed into a fastener, where an end portion of the wire is secured in a predetermined position and axially compressed so as to expand a predetermined amount of wire material radially outwardly and thereby form the head on the wire, and where material flow is directed during axial compression so as to provide the controlled predetermined shape of the head.

Abstract: A method of plastic deformation of metals, alloys and other crystalline materials for controlling their structure and texture comprises the steps of extruding a workpiece through two intersecting passages having equal cross-sections corresponding to a cross-section of a workpiece, the pressing including determining during each passage of a workpiece three main directions corresponding to a flow direction, a perpendicular to the flow plane, and a perpendicular to the first mentioned and second mentioned directions, changing the directions during placement of a workpiece in its initial position for each passage relative to a corresponding position in a predetermined passage by turning the workpiece by a predetermined angle around axes of the main directions, and cyclically repeating the method.

Abstract: A forged-steel connecting rod blank is formed with intentional-break zones extending over one or both of the broad crankshaft-eye surfaces of the connecting rod or as crevices formed radially in the inner surface of the large-diameter bore of the eye and running from an upper edge to a web of the material which is ultimately punched out.

Abstract: A process for converting sheet stock into a seamless outer shell for a toroidal shaped hybrid inflator for air bag inflation systems. In the process a seamless toroidal shaped shell is fabricated from sheet stock by a sequence of process steps comprising first drawing the sheet into a cup shaped blank, with curved transitions between the bottom wall and the sidewall, and then shaping the open end of the cup to the desired toroidal shape while simultaneously thickening the areas adjacent to the perimeter of the open end of the cup and finally removing the central portion of the bottom of the cup--thereby producing the desired shell.

Abstract: A method for producing ratchet devices, the method including the steps of forming a circular recess in a blank metal plate by drawing, compressing the metal plate in a pair of dies so as to reduce the depth of the recess and thicken the side wall thereof, and forming ratchet teeth on and along the inner annular surface of the side wall of the recess.

Abstract: An adjustable, pre-set, threaded and torqued pedal rod has a shaft part and a head part which are selectively adjusted and assembled with the use of screw threads to a pre-selected longitudinal mean dimension and then securely crimped to lock the parts together so that the two parts cannot be separated without total destruction. Screw threads of different size are disposed on two separate tiers to afford torque locking.

Abstract: A pedal rod is made of two separate pieces, a rod part and a head part, joined together by a crimped joint having as many as six elements. The parts may be selectively plated and/or coated to provide environmental resistance or color coding.

Abstract: A method of producing a coupling for pipes includes the steps of subjecting a predetermined length of desired cross-sectional profiled material to a bending process in a mould having a semi-circular portion to form an item of semi-circular shape; forming bent ends of predetermined size on the profiled material; and then coining the bent ends to lie in an identical horizontal plane as a horizontal diameter of the item of semi-circular shape. The coining step is accompanied by a substep of forcing excess material from the predetermined length of profiled material into a zone between the semi-circular portion of the mould and the bent ends of predetermined size on the profiled material.

Abstract: A method of scoring a metal panel such as a can end lid includes forming a first scoreline having a base and a pair of lateral walls and subsequently forming a second scoreline within the first scoreline by indenting a portion of the first scoreline base. The final scoreline may be created by employing two or more scoring operations after the first scoreline has been formed. The apparatus preferably includes a press which supports the first scoring die and second scoring die in such a manner as to establish the desired sequence of scoring operations. This method and associated apparatus provide a scored metal panel or container lid having improved performance characteristics. The resultant lid is characterized by reduced residual strain.

Abstract: Disclosed is a large alloy forging, the forging having an alloy composition selected from one of a nickel base alloy, a cobalt-chromium-nickel base alloy, a nickel-cobalt base alloy and an iron-nickel-chromium-molybdenum alloy, the forging having a grain size of ASTM grain size 3 or finer, as measured by ASTM method E112 and having a tensile strength in the range of 135 to 175 KSI.

Abstract: Disclosed is a large alloy forging and method for making it. The forging having an alloy composition selected from one of a nickel base alloy, a cobalt-chromium-nickel base alloy, a nickel-cobalt base alloy and an iron-nickel-chromium-molybdenum alloy and having a grain size of ASTM grain size 4 or finer, as measured by ASTM method E112 and having a tensile strength in the range of 135 to 175 KSI. The process includes: (1) four upset forgings, (2) a rapid cooling after the final upset cooling, (3) a first and second upset forging with a reduction greater than 50%, (4) a third upset forging with a reduction greater than 25.%, and (5) a forging process with a fourth upset forging with a reduction greater than 50%.

Abstract: A method for forming a shaft with protrusions applies vertical pressure to the shaft to deformably displace material from the shaft to form one or more protrusions. The protrusions retaangularly spaced on and circumferentially aligned relative to the peripheral surface of the shaft. The shaft may be of any diameter, but typically three-eighths inch with the protrusions forming a larger diameter of typically one-half inch.

Abstract: A one-piece metallic belt driven pulley has a hub, an annular belt engaging wall having an outer belt engaging surface and a radially extending web that connects the hub and belt engaging wall. The hub has an internal bore defined by a tubular inner surface. At least a portion of the tubular inner surface that defines the bore has a plurality of axially spaced threads to form an axially extending threaded portion. In use, the threaded portion of the bore is threaded onto an axially extending thread on an outer surface of the shaft to secure the pulley to the shaft. One end of the hub takes the form of a nut having a hexagonal outer configuration that is adapted to be engaged by a tool for screwing the pulley onto the shaft. The other end of the hub forms an axially extending integral spacer, the end of which is located outwardly of an end surface of the pulley.

Abstract: A spider or cross for a universal joint is manufactured by first forging the basic configuration of the cross and thereafter extruding the trunnions into their final configuration. The component is initially hot or warm forged into its basic configuration including a central body and a plurality of trunnions. Thereafter, the trunnions are simultaneously extruded into their final configuration eliminating machining and a loss of materials. As a result, the grain flow of the component is not disrupted for a more reliable part.

Abstract: A fuel injector device has a fuel swirling element disposed upstream of a valve seat and capable of imparting a swirling force to a fuel supplied thereto, a fuel injection nozzle orifice disposed downstream of the valve seat, and a fuel distributing adapter disposed downstream of the fuel injection nozzle orifice and capable of distributing the flow of the fuel injected by the fuel injection nozzle orifice in two directions. The adapter has an axial fuel passage having a fuel inlet of a diameter greater than that of the injection orifice and an outlet end of a substantially "8"-shape having a minimum diameter smaller than that of the inlet end. The adapter can be formed by preparing a blank having an axial fuel passage and then conducting a plastic work by a punch press on an end face of the blank so as to restrict the outlet end of the fuel passage.

Abstract: A transition piece for attaching branch pipes, valves, etc. to a pipe or the like at a position intermediate its ends is formed as a one-piece component by forging, preferably drop-forging, and comprises a flanged end portion, a tapered neck portion and a flared neck portion, said tapered neck portion tapering from the flanged end portion towards a waist portion intermediate the ends of the component, said flared neck portion flaring from the waist portion towards the end of the component remote from the flanged end portion, said component having a throughbore running the length of the component.

Abstract: A process for slitting and recoiling steel which includes first levelling the uncoiled steel to elongate the steel at its thickest point. The levelled steel sheet is then slit into multiple strands, rolled and recoiled.

Abstract: The disclosure relates to a steel anvil extending along a substantially horizontal axis and along a vertical axis and comprising a base (3), a body (2) possessing a round horn (8) and a square horn (15) arranged on either side of a face (10). The disclosure further relates to portable anvils intended in particular for the smithy, in order to enable a farrier to practice his art with a maximum of facilities, even under itinerant conditions.

Abstract: A method of fabricating box section from steel with walls of non-uniform thickness along its periphery. A starting product in the form of round tubing with a wall that is uniformly thick along its circumference is manufactured and rolled into box section with walls of uniform thickness along its periphery. A temperature difference is generated between the flange midsections and the web midsections of the box section with walls of uniform thickness along its periphery such that the flange midsections are at least 600.degree. C. hotter than the web midsections, the flanges are edged and thickened peripendicular to the longitudinal axis of the box section, with the edge length being shortened, by rollers, and the box section is finally cooled with air and/or water subject to standardization conditions.

Abstract: A method of manufacturing a magnetic rotor core member for a rotating-field dynamoelectric machine, particularly a small alternator, including the steps of hot forging a segment of steel bar stock into a core blank approximating the final volume desired for the rotor core member but with the pole piece finger angled outwardly from a central disc section at an angle of 45.degree. to 80.degree., the fingers being shorter than required for the finished pole pieces, de-burring the core blank and gradually cooling it. A shaft aperture is cold punched through the hub of the core blank, the pole piece fingers are bent into a vertical position relative to the rotor disc, and the pole piece fingers are ironed into close conformity with the required finished dimensions, in particular lengthening and shaping the fingers; this is all done in one step in a cold-forging press. The core blank is cold compressed to finished form as a rotor core member. Annealing is an optional step.

Abstract: A method and apparatus for upsetting forged bars to form compressor vane blanks are disclosed which utilize a two-stage upsetting process. In a first stage, the rough forged bar is placed in a first die having a first enlarged cross sectional area such that the end of the bar to be upset extends into the enlarged cross sectional area of the die. The enlarged cross sectional area is shaped so as to have at least three lines of contact with the bar segment during lateral expansion of the bar. In a second upsetting stage, the expanded bar is removed from the first die and inserted into a second die, also defining an enlarged cross sectional area portion such that the expanded portion of the bar extends into the enlarged cross sectional area of the second die. The second enlarged cross sectional area has a cross sectional shape so as to accommodate the previously enlarged portion of the bar such that at least one line of contact is maintained between the bar and the die as the bar laterally expands.

Abstract: A closed-die forging having an annular flat surface portion and a corner portion at an outer periphery of the annular flat surface portion is made by a method consisting of a rough forging process and a finish forging process. In the rough forging process, a rough forged product is shaped so as to have an annular flat surface portion smaller in outer diameter than the first mentioned annular flat surface portion and a conical surface portion at an outer periphery of the second mentioned annular flat surface portion. The conical surface portion is so shaped as to extend increasingly outwards as it extend in the same direction of movement of a punch of a rough forging die for performing a forming operation.

Abstract: A reference standard and a method for manufacturing a reference standard for use in calibrating an eddy current probe is disclosed. The reference standard is produced from a block of metal that is deformed by an indentation tool to provide a notch of prescribed dimensions. The reference standard is compressed along an axis substantially transverse to the longitudinal axis of the notch to substantially close the notch. A family of reference standards formed in this manner can be produced to calibrate an eddy current probe prior to use of the probe in evaluating metal components such as aircraft framework for the presence of fatigue cracks and the like.

Abstract: A method is disclosed for deforming a molybdenum based metal part, which involves press forging a powder metallurgically produced part made of material selected from the group consisting of molybdenum metal and molybdenum metal alloys, at a temperature of from about 1700.degree. F. to about 2300.degree. F. at an average strain rate of from about 5 inches per minute to about 20 inches per minute.

Abstract: The disclosed connection bar is elongated, adatped to overlap respective adjacent ends of two rails, and the top and bottom portions at each end of the bar have elongated contact faces shaped to cooperate flush against respective surfaces on these rails. A pair of holes is provided in a web portion of the bar, and securing devices may be extended through the holes for clamping the bar against the rails. An elongated reinforcing rib may be formed on the web portion, extended across the bar transverse to and between the enlarged top and bottom portions, and located to line up adjacent the ends of the rails when the bar is secured to the rails. Other reinforcing ribs may also be extended across the web portion, transverse to and between the top and bottom portions; and these other ribs are located outwardly beyond the holes.

Abstract: A forging method comprises the following four steps: a first step of disposing a columnar material into a first die and extruding one end portion of the material with a first punch in a direction opposite to the advancing direction of the first punch, a second step of deepending a first blind hole in a second stepped die with a cavity having large and small internal diameter portions, and extruding the other end portion of the material into the inside of the small internal diameter portion of the cavity with a second punch which has been previously extended thereinto, a third step of fitting the first and second blind holes to third punches while exposing the small outer diameter portion from a third die and pressurizing, by means of a sleeve, only an end face portion of the small outer diameter portion formed with the second blind hole to expand the small outer diameter portion of the material toward an outer periphery, and a fourth step of punching out a blind portion of the material.

Abstract: The present disclosure relates to an apparatus and a method for deforming sheet metal plates and more particularly aluminium and steel plates. The objectives of this disclosure are realized by laminating a plate of sheet metal in juxtaposed and parallel strips. This method allows for the formation of spherical surfaces having a variable curvature. These strips are oriented according to predetermined axes according to the expected result.

Abstract: A billet (10) is pressed with a first blocking punch (36, 38). Thereafter, the billet is rotated approximately 90.degree.. A second punch (50) is pressed against the billet while a split ring die assembly (58) substantially surrounds the billet and constrains outward flow of the steel. The split ring die assembly includes projecting regions (64, 66) matingly received in recesses (14, 16) created by the first blocking punch. A finishing punch (90, 92) is pressed through the billet to complete formation of openings (94, 96). Preferably, a trimmer (100) removes any flashing from the finished billet.

Abstract: An improved fastener provides axially extending teeth on a narrow shoulder adjacent the fastener head. The teeth bite into sheet material, and are particularly useful in biting into the surface of a thin sheet which is fastened to a thicker sheet material. The teeth extend from a shoulder formed on a medial collar between the head and a threaded shank. The narrow shoulder has a larger diameter than the end of the threaded shank to which the shoulder is joined. The teeth can be formed by cold-flow of the material of the shoulder so that the teeth axially extend from the outer peripheral edge of the shoulder in order to bite into the thin sheet metal proximate the annular periphery of the aperture in which the threaded shank is engaged. Preferably, the teeth axially overlap the threading of the shank which extends entirely to its junction with the shoulder, and the teeth are fabricated after the shank thread in order to enable such overlap by the teeth.

Abstract: A method for manufacturing a metal substrate for a memory disk wherein a metal blank material (6) is sandwiched between two dies within a metal mould (3) limiting the extent to which the material spreads, using a core member (4) if necessary, each of the dies having a flat and smooth working surface, the compression force and sheet gauge reduction ratio being regulated or the surface roughness and amount of coating lubricants employed being regulated.

Abstract: A method is disclosed for deforming a molybdenum based metal part, which involves press forging a part made of material selected from the group consisting of molybdenum metal and molybdenum metal alloys, at a temperature of from about 1700.degree. F. to about 2300.degree. F. at an average strain rate of from about 5 inches per minute to about 20 inches per minute.

Abstract: A method for providing a tubular node in framework truss structures, such as offshore platforms for oil drilling and production activities of the type consisting of interconnected legs and braces of steel tube elements. For formation of the transition between leg and brace in the node is utilized a blank of rolled plate steel, which is given the desired curved shape corresponding to the curvature of the leg. The blank is pressed or extruded in a suitable press tool formed with an outwardly extending brace stub at the desired angle, which brace stub is designed for welding to a complementary brace tubing in the framework. Thereafter, the blank with the brace stub is welded into the leg proper and constitutes a wall segment of the leg in the node.

Abstract: A surgical implant is disclosed manufactured from cast austenitic stainless steel and cold-forged to a final shape. The endoprosthesis is initially a preform which is cast oversized in shape and dimensions. It is then compressed using the cold-forging process to its final size and shape. Using a cast material as a starting material and then compressing it substantially reduces the porosity of the material and increases its strength compared to a machined product from a wrought material.

Abstract: A method of forming a pipe fitting of unitary construction having a tubular section with a radial flange at one end of the tubular construction. The method includes forming a solid cylindrical bar, upsetting one end of the bar to form a head thereon, drawing the remaining cylindrical portion of the bar to increase its length and decrease its circumference, upsetting the head to form the radial flange, and forming a bore through the flange and remaining cylindrical portion of the bar.

Abstract: A self-plugging blind fastener of the break-stem type, is suitable for fastening apertured sheets together, and comprises a headed tubular body and an elongate stem disposed in the bore of the body. The stem comprises a plug, and a stem-tail connected to the plug by a breakneck which is concealed by overlapping lips. The plug has a stop face, and an annular locking groove between the breakneck and the stop face. The body has a deformable locking collar upstanding above an adjacent region of the upper surface of the head. The diameter of the bore reduces, to provide a stop face and a locking region of smaller diameter, within the head. The fastener is set by pulling the plug into the bore until the stop faces meet, to form a blind head, and then deforming the collar to force the body to bulge into the locking groove of the plug.

Abstract: A method of manufacturing a magnetic rotor core member for a rotating-field dynamomoelectric machine, particularly a small alternator, including the steps of: hot forging a segment of steel bar stock into a core blank approximating the external configuration desired for the rotor core member but with the pole piece fingers shorter than required for the finished pole pieces; de-burring the core blank; coining the core blank into closer conformation to the desired core member configuration; gradually cooling the core blank; rough machining only two opposed surfaces of the hub and base to assure a controlled uniform volume for subsequent processing; cold punching a shaft aperture through the hub of the core blank and simultaneously ironing the pole piece fingers into close conformity with the required finished dimensions, in particular lengthening the fingers; and, finally, cold-compressing the core blank to finished form as a rotor core member in a single cold compression step.

Abstract: An extruded aluminum alloy improved especially in wear resistance and cuttability and comprising 12 to 30% of Si and 0.3 to 7.0% of Cu, with or without 0.3 to 2.0% of Mg, the balance being substantially aluminum. In this alloy, primary Si crystals 40 to 80 microns in particle size occupy at least 60% of the area occupied by all the primary Si crystals in the aluminum matrix, and eutectic Si crystals up to 10 microns in particle size occupy at least 60% of the area occupied by all the eutectic Si crystals in the matrix. The primary and eutectic Si crystals are uniformly dispersed throughout the matrix. A process for preparing the extruded aluminum alloy is also disclosed.

Abstract: A method of manufacturing a scroll member for use in a rotary compressor has the steps of heating a material which has been preformed into a substantially frusta-conical body consisting of a flat upper surface portion provided with a cylindrical projection integrally formed in the center portion thereof and a lower surface portion having a conical surface and a flat projecting surface, and forging the material by a forging apparatus. The heating step compriss a first heating at a temperature in the range from 100.degree. to 200.degree. C. and a second heating at a temperature of 440.degree. C. which is carried out after coating the material with graphite, the coating being applied to the material between the first and the second heatings.

Abstract: A carbon steel with at least 1% by weight carbon and at least one carbide-forming alloying element such as chromium is forged into a construction machine-tool part for engagement with abrasive material, the forging provides a fiber extension direction which coincides with the principal direction of abrasive action.

Abstract: A process for the manufacture of a synchronizing component, provided with a hort toothing having undercut teeth, for a shift transmission by precision forging, in which the teeth, the radially inner side of which lies against a common cylindrical surface and the base of which is placed on a common lower plane surface, being first manufactured with parallel tooth flanks and then subjected to final clenching, permits especially precise formation of the coupling surfaces, the following process steps being essential:(a) by means of preliminary forging a semi-finished product is produced the short toothing of which has teeth (7) having excess dimensions exceeding the finished tooth head (10),(b) by means of one or more subsequent calibrating strokes the cold semi-finished product is acted upon in such a manner that(aa) firstly the tooth head (10) are subjected to preliminary clenching, the radially outer sides of the teeth being supported on the forging-die side,(bb) simultaneously with the preliminary clenching o

Abstract: A method for producing a worm shaft for use in a rotation control valve of a power steering mechanism. The worm shaft is formed with grooves which receive a control body and form therewith a fail safe structure. The grooves are formed evenly so that the permitted range of movement on either side of a neutral position is uniform. A cylindrical member is plastically deformed in two steps to form the outer side of the control valve. Then, while in a die having in inner shape corresponding to the desired outer shape of the worm shaft, a punch, having an outer shape corresponding to the desired shape of the grooves on the inner surface of the worm shaft and an enlarged-diameter portion, is pressed into a hole in the interior of one end of the member to thereby plastically deform the member to the desired final inner and outer configurations.

Abstract: In accordance with the present invention, there is provided a method for increasing the longitudinally compressive and tensile proportionality limits and ultimate strengths of an elongated structural member by applying to the member a longitudinally compressive load. To increase the proportionality limits of the member, a longitudinally compressive load is applied to the member which is close to its maximum load. In order to prevent buckling of the member under such a load, the member is confined in an encasement which allows the member to yield longitudinally without bending. By applying to the member a longitudinally compressive load much greater than the member's original (i.e., untreated) ultimate compressive strength, both the ultimate strengths and the proportionality limits of the member are increased.

Abstract: This invention relates to platinum group metal-containing alloys comprising, apart from impurities:(a) at least 40 wt. % nickel or at least 40 wt. % cobalt;(b) a trace to 30 wt. % chromium; and(c) a trace to 15 wt. % of one or more of the metals platinum, palladium, rhodium, iridium, osmium and ruthenium.

Abstract: For decreasing the width of a thin slab: a turning roll contacts the thin slab being conveyed at a certain contact angle to curve the thin slab; a tension applying device disposed in front and at the back of the turning roll, applys a tension to the thin slab forwardly and rearwardly in the direction of conveyance of the slab. Thus, the slab can be decreased in its width to a satisfactory section with no buckling loop forming portions for forming loops of the hot thin slab at the inlet and the outlet sides of the apparatus for decreasing the width of the thin slab absorb the intermittent proceeding of the hot thin slab in the direction of flow of the material. Thus, the continuous receipt and the delivery of the slab are made possible while the intermittent width decrease is performed, and the combination of the continuous casting equipment with the hot finish rolling equipment is materialized.

Abstract: A method of manufacturing precise sheet metal made poly-V pulleys with poly-V grooves, being uniform in thickness of peripheral wall and free of reduction of mechanical strength, by a step of preliminarily forming a lug in the peripheral wall of a cup-shaped blank and thickening the peripheral wall, a step of forming a plurality of V-grooves in a multiple arrangement on this thickened peripheral wall by pressing from both sides with a V-groove preliminary forming roller possessing a plurality of V-grooves forming ridges and a rotary inner die possessing a plurality of V-grooves while rotating the cup-shaped blank, and a step of pressing this peripheral wall with a plurality of V-grooves with a finishing roller. Furthermore, a method of manufacturing sheet metal made poly-V pulleys having advanced precision, by a step of preliminarily forming lugs and first grooves in the peripheral wall of a cup-shaped blank, and a step of thickening the peripheral wall.

Abstract: A pick type bit is disclosed with an improved socket for a carbide insert. The cutter body of the bit is cold-headed from a steel blank to provide a cylindrical shank and a conical head with a socket in the forward end. The cylindrical shank is roll-formed to provide a retaining groove and an intermediate section is roll-formed to provide an extraction groove between the head and the shank. The cold-heading includes an initial step of squaring-up the forward end of the blank by cold-heading it into cylindrical shape with a flat forward end and then punching the socket. This provides a socket of densified work-hardened steel. The bit is completed by brazing the base of a carbide insert in mating relation with the socket in the head.

Abstract: An improved hot forming method for metals, alloys and the like, and in particular, for difficult to process high strength and high temperature metals and alloys of particular use in aerospace applications, is described, which comprises the steps of generating flow stress data as a function of strain rate and temperature on samples of the material at predetermined strain within predetermined ranges of temperature and strain rate; determining from that data the strain rate sensitivity and power dissipation efficiency of the material within the ranges of temperature and strain rate represented by the generated data; selecting values of strain rate and corresponding temperature for a selected value of the dissipation efficiency for the material; and hot forming the material at the selected strain rate and temperature values to a predetermined shape.

Abstract: A camshaft is prepared from separately formed cams and a shaft. The cams may for example be formed by sintering. The cams are provided with holes which are under-sized and are provided with serrations. They are located on a correspondingly shaped dummy shaft in their required relative orientations and angular positions. Next, the cams are clamped in these positions and the dummy shaft removed. The cams are then heated to red heat and the serrated holes in them broached to bring them to their final size and to concentricity. Finally, a shaft having an exterior profile corresponding to the shape and size of the broached profile of the holes, at ambient temperature, is introduced into the holes and the cams are then cooled so that they shrink fit on to the shaft so ensuring that they are accurately positioned on the shaft. The cams are then released from the jig to give a finished camshaft.

Abstract: Multiple strands of metal slit from strip which varies in thickness from edge to center are separately coiled on the same mandrel into uniformly tight coils by selectively working the strands so as to reduce the thickness and elongate thicker strands more than thinner strands. The working is preferably accomplished by imparting reverse bends to the strands while tensioning them in amounts less than the tensile yield strength of the metal.