Abstract: A method of producing an ellipsoid form from an expanded metal foil net teaches the steps of placing a sheet of expanded metal net on a work surface adjacent an open-ended hollow cylinder having the interior shape of a semi-ellipsoid, moving a first piston having the exterior shape of a semi-ellipsoid against the expanded metal sheet and into said open-ended cylinder to form the sheet into a semi-ellipsoid piece having a closed end and an open end, and subsequently moving a second piston into the open-ended cylinder to close the open end of the semi-ellipsoid piece and thus complete formation of the ellipsoid form. The metal foil may be a continuous sheet transversely slip and fed in unstretched form from a roll to the edge of said work surface, then stretched across the work surface and detached from the continuous sheet to provide the expanded metal net sheet to be formed into an ellipsoid.

Abstract: A shaving system that includes a holder and a blade member secured to the holder. The blade member has an aperture that defines an annular sharpened edge with main facet portions that converge at an angle of less than 30.degree. and supplemental facet portions that are extensions of the main facet portions and define an ultimate tip defining portion that has an included angle of less than 30.degree.. The supplemental facet portions are offset in the same direction from the main facet portions each at an angle of less than 175.degree., the outer main facet portion defines a shaving plane, the ultimate tip is disposed above the shaving plane less than 0.1 millimeter, and the bisector of the included angle defined by the supplementary facets is disposed at an angle to the shaving plane in the range of 15.degree.-35.degree..

Abstract: Flat stamped electrical contact device (2) has a contact edge (8,8') which extends from the first major surface (4) to the second major surface (6) of the device. The contact edge surface (8,8') is smooth for substantially its full width and does not have a fractured portion or a burr extending from the second major surface (6). The smooth straight surface is produced by steps of coining the opening produced during the initial punching operation at a location adjacent to the second major surface after the opening has been punched and then shaving the edge to produce the finished contact surface.

Abstract: A method of making a gasket of the kind wherein at least one aperture is blanked out at a desired location in a metal plate before or after, or at the same time as a peripheral corrugation is formed around the margin of said aperture, is characterized in that said corrugation is formed in the sheet around the intended location of said one aperture after an initial step of forming at least one preliminary aperture at said location, the shape and configuration of said preliminary aperture being selected in accordance with the proximity of the said one aperture to the edges of the plate and to the location of any other intended aperture in the plate, so that the corrugation formed after said preliminary aperture forming step exhibits controlled geometry and plastic deformation when subjected to compression.

Abstract: A method of making a brazeable metal pipe which has elliptical tube-insertion apertures and guide lugs extending from at least one of the opposite edges defining the minor axis of each aperture, with the guide lugs extending in the direction of insertion of flat tubes. The method in an embodiment comprises the steps of: bending a part of a raw strip, which may be previously embossed to form recesses, so as to provide a bulged portion arc-shaped in cross section and connected to at least one unbulged flat portions; pressing inwardly to form inward swells; subsequently punching each inward swell to provide the tube-insertion aperture so that at least one of the opposite edges located at ends of the minor axis of said aperture remains unpunched; and finally bending the at least one unbulged portions to produce the finished pipe.

Abstract: The present invention provides a method of manufacturing fins for heat exchangers, wherein a collared through-hole of a prescribed height can be easily formed while using volatile oils as machining oil, even if the material of the metal plate is thinner and harder than conventionally used.

Abstract: A base (10) and the method for fabricating the corners (32) of the base (10) of a piece of furniture (12) from tubing (18) by notching the tube (18). The notching removes a metal from the tube (18) along the first pair of extremities (40) converging to an apex (44), and along a second pair of transverse extremities (52). Additional material is removed from the spaces (38) by removing a plug from the tube (18) adjacent the apex (44) in the shape of a bowl having two parallel sides (56), a third side (58) perpendicular thereto and a point (44). The tube (18) is folded at each point (44) creating corners (32) in the tube (18) each with a space (38) and an enlarged relief space (46) therebetween to allow fluids used in the post-fabrication operations, i.e., washing and painting, to flow quickly therefrom thus increasing drying times. The gussets (62) are welded to the tube (18) to add strength to the base (10).

Abstract: A combined punch and flange forming tool comprises a double-ended female die 7 and a punch 4. Initially, a first portion 2 of the female die is used in association with a cylindrical portion 8 of the punch to cut the required hole in the work-piece 11. Thereafter, the female die is reversed and flange forming profiles 17,18 the punch and female die respectively are used to deform the work-piece to provide the desired flange surrounding the hole.

Abstract: The invention relates to a method of producing a telescopic cover by bending a flat sheet material blank, in which a diamond-shaped cut-out is provided in the sheet material blank and is separated from the adjacent outer edge by a continuous material zone which is stretched without cracking during the bending operation to form a corner zone with a rounded contour.

Abstract: This method relates to the production of connectors each embodied by a row of substantially U-shaped clips formed in their curved part with a row of regularly spaced-apart apertures which separate the hinge elements from one another. The following metal deep drawing and pressing operations are performed consecutively in the central part of a metal strip, forming an aperture of reduced cross-section in the center of the place intended for each aperture required to be present between two hinge elements; widening each such aperture and pressing in the edges to form a collar which projects from a surface of the strip; bending the sides of each collar around on to the corresponding surface of the metal strip; and bending the strip round into a U-shape by the surface towards which the collar edges have been bent round being inwardly directed.

Abstract: A circular hole is defined in a top plate stock of thin sheet steel, and a peripheral edge of the circular hole is raised and radially outwardly expanded into a substantially frustoconical first flange blank. Then, a peripheral edge of a proximal portion of the first flange blank is raised and radially outwardly expanded into a substantially frustoconical second flange blank contiguous to the first flange blank, the second flange blank having a lower portion beneath the peripheral edge of the proximal portion. Finally, the third flange blank is drawn into a tubular flange which has a predetermined inside diameter and a predetermined height.

Abstract: A die set for forms fins of heat exchangers and a manufacturing device using the die set. The die set for manufacturing fins of heat exchangers, comprising a punch and a die for forming a projected section, which is formed along an edge of a hole bored in a metal plate, into a collar with a prescribed height. The die has a hollow section into which the punch is capable of entering and the outer circumferential face of the punch is a tapered face in the form of a truncated cone. The tapered face faces the inner face of the die when the upper end section of the punch proceeds beyond the upper end of the projected section, which is held between the outer circumferential face of the punch and the inner face of the die, and the projected section so held is extruded by reduction of the distance between the outer circumferential face of the punch and the inner face of the die, which hold the projected section therebetween, caused by movement of the tapered face of the punch into the hollow section of the die.

Abstract: Disclosed is a water aerosol or fog-generating system comprising a pipe having a plurality of atomizing nozzles threaded to the walls thereof. The pipe has thin walls made from an alloy, preferably stainless steel, with nozzles affixed at various points along the piping. A plurality of pilot holes are provided at each nozzle location and the edges of each pilot hole are deformed inwardly by a punch so that more surface area is provided for threading the walls of the pilot hole. Preferably, the pilot hole has been reamed after punching and before the threads are made. An atomizing nozzle is mated with the threads on the punched and reamed hole. Also disclosed are seals to be placed between the nozzle and the exterior piping surfaces.

Abstract: Apparatus is provided for forming strips of sheet metal into supports or hangers for ducts and the like. The apparatus comprises a reel for holding a coil of sheet metal for being formed into strips, a strip feeder for extracting lengths of sheet metal from a coil of sheet metal held in the reel, and a combination brake, punch and shear mounted on the reel for causing a 90 degree bend in a portion of the strip near the end to be sheared off, for punching at least one hole in, and for shearing, each of the extracted lengths of sheet metal from the coil, the combination brake, punch and shear being configured for causing the bending, punching and shearing with a single operational stroke, a hole being punched in the extracted length of sheet metal between the bend and shear lines before the bend is made and before the strip is sheared form the coil of sheet metal.

Abstract: A method for forming a threaded dispensing opening for a cylindrical drum container having a generally flat circular closed bottom, a generally flat circular closed top, and a cylindrical side wall comprising the steps of forming an aperture in the drum top and drawing the drum metal adjacent the aperture upwardly to define an upwardly extending annular shoulder. The shoulder is then compressed downwardly to thicken the shoulder and a female threaded portion is formed on the inside of the annular shoulder which is receptive of a threaded closure member.

Abstract: A precision blanking tool mounted in a press, which may be a transfer press, comprises an upper part with an upper tool support and a lower part with a lower tool support. One hydraulic unit is accommodated in the upper part of the precision blanking tool and another in the lower part. The upper hydraulic unit is inserted with the upper tool support in an interchangeable frame and the lower hydraulic unit with the lower tool support in another frame. The hydraulic units are controlled with pressurized oil by drive means forming a separate unit.

Abstract: A process for making gaskets consists in forming, in the body, holes regularly distributed along each line intended to receive a sealing element, in effecting, by stamping, the formation of a groove along each line intended to receive a sealing element, and in effecting the molding of sealing elements in each groove which the body comprises.

Abstract: A progressive die for producing collared holes in a sheet. The die includes a first station having a pattern of three punches producing three spaced apart holes in the sheet. A main punch at the second die station is extended into the three holes producing a single hole with portions of the sheet extending therein. The straightening punch mounted at the third station of the die has a diameter larger than the single main hole and is extended therethrough bending the portions extending into the hole outwardly forming a collar. The curling punch mounted at the fourth station of the die, curls the distal end of the collar outwardly.

Abstract: A progressive die for producing collared holes in a sheet. The die includes a first station having a pattern of three punches producing three spaced apart holes in the sheet. A main punch at the second die station is extended into the three holes producing a single hole with portions of the sheet extending therein. The straightening punch mounted at the third station of the die has a diameter larger than the single main hole and is extended therethrough bending the portions extending into the hole outwardly forming a collar. The curling punch mounted at the fourth station of the die, curls the distal end of the collar outwardly.

Abstract: In a progressive die for punch press operations in which a strip of material is fed into the press and sequential operations are conducted on the strip including the separation of parts from the strip. The die is provided with a construction which forms an integral carrier tab between the parts to be separated. In the embodiment ilustrated, the operation is the manufacture of rotor and stator laminations for a dynamoelectric machine. The strip of material is fed into the press in which the die is mounted, and the respective rotor and stator laminations are formed in a series of workstations within the die. The improvement in the die construction is a punch station for substantially but not completely separating the rotor lamination from the strip. Thereafter, additional operations are constructed on the strip, the rotor lamination being completely separated at a subsequent workstation.

Abstract: An improved blank base and method of making a bird repellant structure. The method comprises forming slots into a continuous base strip for the formation of repellant members. Said repellant members have a single forward diagonal edge for the simple cutting of repellant barbs.

Abstract: A simplified nut having a substitute "thread" in the form of an edged flat which can receive a threaded member. The flat or flats are swedged from material preferably in sheet form surrounding a smooth bore opening in which the flat(s) entirely extend. The edges of the flat(s) may be circular or helical, continuous or discontinuous. The device and its forming method eliminates separate handling and cleanup associated with conventional thread forming methods.

Abstract: A method for forming a threaded dispensing opening for a cylindrical drum container having a generally flat circular closed bottom, a generally flat circular closed top, and a cylindrical side wall comprising the steps of forming an aperture in the drum top and drawing the drum metal adjacent the aperture upwardly to define an upwardly extending annular shoulder. The shoulder is then compressed downwardly to thicken the shoulder and a female threaded portion is formed on the inside of the annular shoulder which is receptive of a threaded closure member.

Abstract: A thin edge orifice disk is defined as a disk having a thickness to main dimension or diameter ratio of at least 1:80. The manufacturing of an accurately sized orifice in the disk is accomplished by means of a progressive die. One of the stations of the die provides a coining operation on the orifice. Such coining operation is adjustable by means of a micrometer adjustment.

Abstract: A method of forming a collar-shaped protrusion on thin plate material by relatively bringing a forming punch having the outer diameter varying stepwise into the forming hole of a forming die and during forming, punching a small diameter hole by means of a punch-through punch incorporated in said forming die. During the remainder of forming, ironing and burring are performed on the protrusion to form a collar for heat exchanger fins. The die set shaped for carrying out the steps is also included. Since these steps can be performed as a single continuous series of steps, heat exchanger fins of high accuracy can be manufactured with fewer tools, and at less cost and in less time than heretofore.

Abstract: A precision blanking tool mounted in a press, which may be a transfer press, comprises an upper part with an upper tool support and a lower part with a lower tool support. One hydraulic unit is accommodated in the upper part of the precision blanking tool and another in the lower part. The upper hydraulic unit is inserted with the upper tool support in an interchangeable frame and the lower hydraulic unit with the lower tool support in another frame. The hydraulic units are controlled with pressurized oil by drive means forming a separate unit.

Abstract: Strip feeding mechanism intended for use in a stamping and forming machine comprises an intermittently rotated sprocket wheel which is located adjacent to the operating zone of the machine in which the stamping and tooling is located. The strip material is held against the periphery of the sprocket wheel by a retaining shoe so that the sprocket teeth will enter pilot holes in the strip and advance the strip during feeding intervals. During non-feeding intervals, the pilot pins which are part of the stamping and forming tooling, will adjust the position of the strip relative to the tooling performing the operation thereon. The construction of the biasing shoe and the sprocket wheel is such that the strip is not firmly held by the feeding mechanism and can be moved by a very slight amount by the pilot pins in order to position the strip precisely in the operating zone.

Abstract: Disclosed herein in dies for forging a gear-shaped part made of a sheet metal, comprising a cylindrical die for forming, in cooperation with a cylindrical punch, tooth portions and bottom land portions at a peripheral wall portion of a cup-shaped work integrally formed from the sheet metal, wherein ridges and grooves provided at the inner peripheral surface of the cylindrical die in the axial direction of the die in order to form the tooth portions and the bottom land portions are such that, in the direction from an insertion-side opening of the cylindrical die toward the depth of the die, the height of the ridges is gradually increased to a final height, then the width of the ridges is gradually increased to a final width, and thereafter the depth of the grooves is gradually decreased to a final depth.

Abstract: A retainer clip to fixedly position a mat relative to an underlying carpet particularly suited to automotive environments. The retainer clip is formed from a single piece of generally rectangularly shaped resilient material which has a cut-out cut in a first portion thereof, the cut-out including a series of V-cuts at one end and a control member at the other end. The retainer clip further has two pointed members cut along each edge of a second portion thereof. The retainer clip is then stamped so that the end thereof adjacent the V-cuts is bent thereby causing the V-cuts to erupt as teeth, and the two pointed members are bent so as to be laterally displaced, thereby forming two prongs. The retainer clip is then bent on itself to form a U-shape. In operation, the two prongs are caused to enter the carpet backing in order to anchor the retainer clip thereto.

Abstract: A process for manufacturing toothed parts having a tooth profile on a portion of their outline. The process utilizes a press machine having top and bottom die sets with stock interposed therebetween at uniform intervals in sequence with the vertical operation of the press machine. The process includes a first step wherein a center hole is stamped in said stock and, a second step wherein a window hole corresponding to the exterior peripheral tooth profile is stamped in said stock using the center hole as a reference, a third step wherein a tooth profile having a tooth width greater and a tooth height lower than the final tooth profile is rough-formed on one side of said window hole, and a fourth step wherein the exterior periphery of said rough-formed toothed part undergoes stamping and ironing operations concurrently with the processing of the final tooth profile.

Abstract: Stamping and forming machine has first and second tooling assemblies which are movable relatively towards and away from each other. Pilot pins are mounted on, and moved with, the first tooling assembly. The pilot pins enter pilot holes in the strip material and are movable on the first tooling assembly between extended positions and retracted positions. When the tooling assemblies are in their open, or separated, positions, the pilot pins are in their retracted positions and clearance is provided to permit feeding of the strip between the two tooling assemblies. As the tooling assemblies move to their closed positions, the pilot pins move to their extended positions and perform their piloting function. The pilot pins are actuated by an actuator which is separate from the actuator which moves the tooling assemblies.

Abstract: A method and apparatus (50 or 110) for forming bolt and center-pilot mounting openings (36, 30) in vehicle wheels (16 or 112), particularly styled-disc vehicle wheels. A preformed rim and disc assembly is engaged and fixtured around the rim bead seat (20, 22) with the inboard disc face resting on a lower die assembly (82) and without plastic deformation to the rim or disc. An upper die assembly (52) having an array of bolt hole punches (56) is moved into piercing-and-coining engagement with the disc to form the bolt openings. Continued motion of the upper die assembly pushes the disc and lower die assembly into shearing engagement with a center punch (76or 76a or 76b) which forms the center-pilot opening. The axes (BH, CH, BS) of the bolt openings and/or center-pilot opening and/or bead seats may be aligned or offset from each other.

Abstract: A method of controlling the clamping movement of a single action drawing press having a fluid actuated pressure member wherein movement of the pressure member is interrupted by stops after a predetermined range of movement toward the base of the press.

Abstract: A method of making a knockout plug in a sheet of metal is provided. The method comprises the steps of: shearing the sheet metal along a majority of a perimeter of a geometric shape so that a plug is produced retained to the sheet metal by at least one retaining strip; cold working at least one sheared area at a pressure sufficient to cause the sheared sheet metal in the area to coalesce; and shearing the retaining strip so that the sheet metal has been sheared along the entire perimeter of the geometric shape. An appliance having a metal casing and a knockout plug stamped in the casing for providing a vent in the cabinet is also provided. The knockout plug is fully sheared along its entire perimeter and has an area along its perimeter that has been cold worked to produce coalesce between the sheared metal.

Abstract: A tapping machine has a plurality of punches for punching a plate-shaped workpiece and extruding or plunging the punched holes and a plurality of tapping units for carrying out the tapping operation continuously in the tapping machine. A free positional workpiece transfer-and-position device is provided which moves the plate-shaped workpiece in the longitudinal and transverse directions of the work area of the machine. The plurality of punches are provided in the direction transverse to the longitudinal direction of the machine. First operating means provide an operating force for the tapping units and second operating means provide an operating force for the punches.

Abstract: A metal fastener for a report folder and the method of manufacturing same comprising the steps of forming the fastener head, forming a single prong portion extending from the periphery of the head, and lancing the prong portion to form two separate prongs.

Abstract: A slotted retaining plate for use in a tubular reactor within an analytical system. The reactor contains inert packed material which provides for the necessary flow path length for a fluid stream entering the reactor. The retaining plate is extremely thin and has an array of slots which permit the necessary flow of the stream through the reactor, but retain the packing material within the reactor. The design of the slot array in the retaining plates essentially eliminates any possible impediment to the stream flow. The slots are adjustable to provide more flexibility in slot size control to allow use of smaller packing particles within the reactor and improve the instrument resolution in, for example, an amino acid analyzer.

Abstract: A one-piece piston is produced by die pressing in a single step, a previously forged blank to bend an annular cylindrical collar thereon and at the same time form a fire rib between two lugs which are pierced in the die-pressing tool so that eyes are formed in the lugs and the latter are calibrated by the piercing operation.

Abstract: A guide vane ring for a return flow passage in axial fans comprises a ring (3) intended for placing in the return flow passage (4) coaxial with the impeller (6). A plurality of guide vanes (7) are formed integral with the ring and distributed round its exterior circumference. In a method of producing such a ring integral with its vanes, separate longitudinal slits are formed in a line one after the other in a metal strip. A cut is made transverse the strip between one end of each slit and one long edge of the strip. Portions of the band thus cut free are bent out from its plane and formed to a desired configuration, whereafter the formed band portions are bent such that the transverse cut lines will extend substantially at right-angles to the unformed flat band portion. This flat band portion is cut to desired length, formed and joined together into a circular ring with the portions formed to desired configuration forming exterior, substantially axially disposed guide vanes.

Abstract: A method of forming a spray nozzle along a fluid conduit includes forming a hole into a length of tubing and then providing a countersink for the hole. A portion of the tubing is then depressed inwardly along an imaginary line along the tubing outer surface that is parallel to the central tube axis and that passes over the hole. An apparatus for carrying out the method is also disclosed.

Abstract: A pipe flange with a heavy welding neck which is hot formed from a circular section of steel plate having a small co-axial hole in the center.The steel around the hole is shear-formed downward and outward by a tapered die plug which is forced through the small hole, forming an integral neck on the flange. A supporting ring die is radiused at its inner corner to form a suitable fillet radius at the junction of the neck with the flange proper. A suitable preforming or post-forming operation may be required to compensate for any deflection in the workpiece out of planar configuration.

Abstract: A device for corrugating a sheet material with forming staggered cut corrtions, comprising a mechanism 1 for feeding a sheet material 2 to at least two punches 3, 4. The punches 3, 4 are mounted for reciprocating motion on both sides of the material 2 in the plane perpendicular to the plane of the material 2 and over the surface of the material 2 at right angles to the direction of its feeding. The device is provided with dies 12, 13 disposed on both sides of the punches 3, 4 in the direction of feeding the material 2, with a clearance being not less than the thickness of the material 2. The dies 12, 13 are adapted to reciprocate relative to the punches 3, 4 at right angles to the plane of the material 2 such that in the process of forming the corrugations the punches 3, 4 are forced in the material 2 between the oppositely lying dies.

Abstract: A windshield wiper yoke and a method for producing same is described. The wiper yoke is formed from a single strip of sheet metal which is bent to have a U-shaped cross-section. The web of the yoke includes a plurality of slots each of which extends in width to or beyond the imaginary bending lines. With slots provided in accordance with the invention, the wiper yoke exhibits relatively good aerodynamic behavior at high vehicle speeds.

Abstract: A method for producing an electrode structure for use in an electron gun, especially an in-line type electrode structure for use an electron gun of a color picture tube. The electrode structure dispenses with auxiliary electrodes by forming its three cylindrical members integrally by press work. After the pressing step, the inner edge of the bottom portion of each of the cylindrical members is beveled to provide a tapering surface having a desired circular cross section. By forming a circular groove in the bottom portion, opposite to the tapering surface, the formation of the tapering surface is made more exact.

Abstract: In an automatic punching and bending machine the interspace between the bending device and the punching device is adjustable in order to make the interspace as small as possible and to adjust that interspace in dependence on the length of the working piece of a band material, thereby gaining the advantages that series of different work pieces of high precision can be produced in the same machine. The bending device is removable and can easily be replaced by another one which has been reset in a preceding working process. Therefore standstill periods of the machine are reduced.

Abstract: Immediately after a composite electric contact is made from wires by cold welding and in a manner as it has been cold welded, it is brought onto a supporting metal and subjected to pressure and resistance heat exerted by a pair of electrodes whereby the contact and the supporting metal are spot welded in situ without adversely affecting the supporting metal such as warping thereof and whereby cold welded abutting ends of the contact are released from stress which is produced by cold welding and the contact is annealed in whole.

Abstract: An improved vapor-liquid contact grid apparatus which maximizes the generation of small drops and which is inexpensive to manufacture and easy to construct is disclosed. The grid apparatus consists of multiple layered grids, each grid being formed of upright grid members and connectors. The grid members carry vanes, formed from the member itself by a process of slitting and bending, which vanes extend out into the region between the upright grid members, thus restricting vapor passage, providing drip points and increasing the effective surface area for gas-liquid exchange. The grid members and connectors are arranged in an "egg carton"--like fashion to provide a simple, yet sturdy, grid.

Abstract: An easily openable container closure comprising (1) a shell of a unitary structure including a top and a cylindrical skirt, said top having an annular top surface portion leading to the upper end of the skirt and a pull ring connected to a part of the inner peripheral edge of the annular top surface portion through a linking piece, and the annular top surface portion and the skirt having a pair of breaking weakened lines formed along the phantom lines extending from both side edges of the linking piece, and (2) a sealing member positioned within the shell for closing an opening present in the top surface of the shell. The annular top surface portion of the shell at least includes a first annular portion extending inwardly from the upper end of the skirt and a second annular portion extending downwardly and inwardly in an inclined manner from the first annular portion.

Abstract: A progressive stage forging machine is provided for forming an article in stages by means of a plurality of dies and cooperating punches, carried on a ram, wherein more than two forging blows are required to complete the forming of the article. The invention particularly provides a forging machine of the three-blow type having three punches and three cooperating dies, wherein two of the dies are carried on a member to permit alternating changes of position of those two dies, thereby eliminating a transfer mechanism between the two dies and achieving a one hundred percent increase over the production rate of presently available forging machines of the three-blow type.

Abstract: A machine having blanking, barb forming and bending stations is provided for making a coil of metal tape from a substantially planar linear strip of metal stock wherein such strip is fed in sequence to the stations in a single pass through the machine to respectively edge notch the strip into barbs, upset the barbs into inclined relation to the plane of the strip and then edge bend the strip in the plane of the strip to form it into identically angularly displaced adjoining linear segments of equal length to make a generally annular coil of barbed metal tape.The method of this invention features forming spaced openings along a longitudinal axis of a substantially planar linear strip of metal stock, positioning the strip by means of its openings and edge bending the strip in the plane of the strip adjacent its openings to form the strip into a coil having identical angularly displaced adjoining linear segments.