Abstract:
In the automated manufacture of helical coils from sheet-metal blanks, each station of a rotatable set or carrousel of winding stations picks up a flat elongated blank from a stationary loader and securely grips and locks one end in an angled position against a slightly-tapered arbor whose subsequent rotation then causes the blank to become tightly wrapped helically about the arbor while retractable ironing plates stretch-form it and while a second locking mechanism positions the opposite end of the blank untl wrapping is completed. The single thrust of a shaped actuating rod causes a locking member to both position itself and move into a clamping relation with the one end of the blank and the arbor, and both the second locking mechanism and the ironing plates are of toggle-type constructions which enable them to hold securely until positively released. Arbor rotation, and operation of the second locking mechanism, are powered in response to motion of the carrousel relative to stationary structure, and fluid-powered actuators serve to drive the thrust rod and ironing plates under control of detectors responding to angular positions taken up by the carrousel.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to improvements in the manufacture of helical coils, and, in one particular aspect, to novel and improved apparatus for the reliable automated manufacture of helical anchor-bolt coils from pre-cut flat metal blanks. Such coils are useful as elements of expansion-type fasteners, or anchor bolts, like those of my U.S. Pat. No. 3,881,393, dated May 6, 1975. 
     Helical coils are commonly produced from continuous stock, whereby a sustained hold or grip and control of the material can readily be maintained until each desired helix is fashioned and cut off as a separate coil. In some instances, however, it is a handicap that the cross-section of continuous stock cannot conveniently be a variable one, and the designer and manufacture must accept that limitation unless willing to resort to hand-worked shaped blanks and non-automatic coil forming. Stock in the form of separate flat pieces, or blanks, presents a classic production dilemma, because of problems associated with handling, conveying, gripping and feeding such parts during processing. In the case of blanks suitable for formation of coils used in expansion fasteners according to my said U.S. Pat. No. 3,881,393, the individual flat sheet-metal pieces of stock are tapered in width and have no flanges, perforations or other features which might assist in their handling; however, such blanks are nevertheless processed automatically into closely-controlled helical coil form in accordance with the practices disclosed herein and with the aid of apparatus constructed according to the present teachings. 
     SUMMARY 
     By way of a summary account of practice of this invention in one of its aspects, a stack of elongated, narrow and tapered sheet-metal blanks is disposed at a stationary feeding or loading site, whence the individual blanks may be delivered, in succession, into the grasps of different ones of a multiplicity of work stations located in equi-angular distribution about the periphery of a drum-like support which is rotated at substantially constant speed about a vertical central axis. The carrousel array of work stations is turned by a suitable power source, such as an electric motor, and each work station features a vertical arbor or mandrel about which a blank may be wrapped helically as the arbor is rotated by gearing which meshes with a relatively-stationary ring-gear or rack. Each station is further provided with a pair of gripping and releasable locking mechanisms, one located at an upper arbor position where winding is to commence and another located alongside a lower arbor position where winding is to be completed. The upper locking mechanism includes a separately-powered tooth which is both rotated and moved laterally to bite one end of a blank into firmly-locked abutting relation with the arbor, and the lower locking mechanism includes jaws which hold down the other end of the blank after being toggle-actuated by camming as the carrousel moves and which are slidable radially to allow the blank to be drawn toward the arbor as winding progresses. Once one end of a blank has been locked with an arbor, a pair of oppositely-disposed plates is separately powered to closure about the arbor, where the plates &#34;iron&#34; or stretch-form the blank during its coiling. Upon completion of the coiling, the side plates and locking tooth are seaparately actuated to release the coil, and the locking jaws by then have fallen open as the blank end was withdrawn from them in a substantially radial direction; further a return spring associated with the locking jaws mechanism will also by then have re-set that mechanism to a radially outer position where it may be re-loaded. 
     Accordingly, it is one of the objects of the present invention to provide for novel and improved automated manufacture of helical coils wherein individual flat blanks are gripped at opposite ends and are oriented and caused to wrap themselves about a forming member with a predetermined pitch of winding and are ironed and released as finished coils. 
     A further object is to provide unique and advantageous apparatus for reliable automated manufacture of helical coils from pre-cut sheet-metal blanks, including rotated arbors associated with blank-holding mechanisms which cause the blanks to wrap themselves into helical coils of desired pitch and dimensions. 
     Still further, it is an object to provide novel automatic coil-winding apparatus in the form of a rotated carrousel of work stations each of which picks up a pre-cut flat coil blank, locks one end to a rotated arbor and the other to a movable pitch-regulating locking mechanism, and wraps and stretch-forms the blank to a desired helical form before releasing it, and to provide unique and useful locking mechanisms for the handling of flat blanks and the like. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Although the aspects of this invention which are believed to be novel are set forth in the appended claims, additional details as to preferred practices and as to the further objects, advantages and features thereof may be most readily comprehended through reference to the following description taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a pictorial view of a helical expansion-fastener coil such as may be advantageously fashioned automatically according to this invention; 
     FIG. 2 provides a pictorial representation of an automated helical-coil manufacturing apparatus constructed in accordance with the present teachings, including an associated blank-feeding installation; 
     FIG. 3 is a view, on an enlarged scale, of a work station and blank-feeding installation such as appears in the apparatus of FIG. 2; 
     FIG. 4 is a front end view, with portions broken away to expose certain structural details, of a work station such as is illustrated in FIGS. 2 and 3; 
     FIG. 5 is a partly cross-sectioned detail, in enlargement, of an arbor locking mechanism such as appears in the FIG. 4 view of a work station; 
     FIG. 6 is an end view of the actuating rod and locking-mechanism shaft shown in the detail of FIG. 5, together with dashed linework representing their alternative positioning during use; 
     FIG. 7 illustrates one of the blank locking mechanisms of FIG. 4 in its cammed and toggle-held gripping condition; 
     FIg. 8 depicts a pair of ironing or stretch-forming shoes such as are used at each of the work stations such as those shown in FIGS. 2, 3 and 4, together with a dashed-linework representation of an associated actuating mechanism; and 
     FIG. 9 is a view from above, showing further details of a blank-locking mechanism and cooperating slide rail used to position the lower ends of coil blanks being fashioned by the apparatus as shown in FIGS. 2, 3, 4 and 7. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The helical coil spring 11, in FIG. 1, is of a type which is useful in the construction of expansion fasteners, such as those described in my U.S. Pat. No. 3,881,393. For those purposes, the coil 11 is fashioned by helically winding a flat strip of a suitable spring-metal such that the turns are axially spaced, and each successive turn, from top to bottom, is of axially-longer dimensions, as shown. Further, the top end 11a and bottom end 11b preferably lie in planes transverse to the direction of axial elongation of the coil, also as shown. 
     The flat strip or blank, 11&#39;, from which a coil such as 11 may be wrapped, has a distinctive trapezoidal configuration such as appears in FIGS. 2 and 3, with the narrower upper end, 11a&#39;, being parallel with the lower wider end, 11b&#39; (FIG. 3). There is a high degree of elongation, and the width of the blank increases progressively from the upper to lower end. FIG. 2 illustrates a sloping chute or conveyor 12, in which a stack of such blanks, 11&#34;, is readied for feeding of the blanks one-at-a-time to work stations of a drum-like rotatable carrousel 13 as such stations become radially aligned with the stationary blank-loading installation 14. As is illustrated in FIGS. 2 and 3, a blank 11&#39; which has been poised for loading onto a work station has a substantial length 11c extending freely and inclined upwardly so that the end 11a&#39; may be engaged by an arbor of a work station as it turns past installation 14. For the latter purpose, each of the multiplicity of like work stations, such as the six stations 15a-15 f, is carried at equally-spaced positions on the outer periphery of a cylindrical or drum frame, 16, such that they may be moved past the blank-loading installation in succession as the frame is rotated in the direction of arrow 17 about a vertical axis 18--18 (FIG. 2) by suitable motive means such as an electric motor (not shown). Preferably, the lowermost or first blank in the conveyor 12 is automatically ejected from the conveyor, downwardly and outwardly, each time one is needed for the fresh loading of a work station, although the same thing may be accomplished manually in an alternative arrangement. When the ejection is automatic, a narrow blade or plate 19 (FIG. 3) of about the thickness of a single blank is propelled in the intended direction, represented by arrow 20, and drives the first blank, represented by dashed linework 21, to the loading position, responsive to the force exerted by a double-actuating pneumatic ejection piston-cylinder unit 22 (FIG. 2). The latter unit is actuated to drive blade 19 downwardly when a work station approaches installation 14, by a suitable position-responsive switch not shown, and to retract the blade and hold it in readiness for another ejection thrust after a work station leaves the loading position of installation 14. When a blank is driven to or otherwise placed in the poised loading position shown for blank 11&#39; in FIGS. 2 and 3, it is held there, relatively lightly and releasably, by the edge-clamping actions of spring fingers such as 23, or the like; sidewise forces will dislodge the blank, as intended, once a work station advances to meet it and pick it up from its poised loading position. 
     Each of the work stations, 15a-15f, includes a vertically disposed blank-coiling arbor, 24a et seq., held in a framework, 25a et seq., and rotated by a pinion-gear unit, 26a et seq., which meshes with and is turned by its movement relative to an arcuate stationary rack or partial ring gear structure 27 as the carrousel is rotated about axis 18-18. The engagements between a pinion unit, such as 26a, and the rack structure 27 begin as a blank is loaded at the site of installation 14, whereupon an arbor such as 24a begins to turn for purposes of coiling a blank; however, after a blank is fully coiled into the desired helix, such as may occur when it reaches the site of discharge station 15d, the arbor need not be turned in the same way and the rack structure is discontinued from there fully around to the loading site. Nevertheless, for purposes of setting the arbor accurately in a predetermined angular orientation in its framework, so that it may properly grasp and hold a blank, a camming action is developed between an arcuate cam member 28 and an arbor-mounted cam follower, 29a et seq., having an arcuate cut-out, 30a et seq., which matches the curvature of cam member 28 and thus forces the arbor to be angularly set in a desired orientation for pick-up of a blank at the site of installation 14. Cam member 28 is of course effective over the arcuate region, angularly about axis 18--18, where ring-gear unit 27 is not effective to turn the arbor, and vice versa. 
     With its arbor angularly set, each work station is turned with the carrousel until its arbor, such as 24a (FIG. 3), is disposed at the back of the upper end of a poised blank, such as 11&#39;. When that occurs, a switch (not shown) responds to the relative positioning of the work station next to the installation 14 and causes the double-acting piston-cylinder unit 31a, of units 31a et seq., to depress a thrust rod 32 (FIG. 4) within a mount 33 for the arbor 24a. That thrust rod is keyed angularly by a pin 34 which passes through a slot 35, such that a shaped end 36 of the thrust rod may coact in a double cam-like way with a cross-piece of pin 37 extending transversely through the mount or head 33 for the arbor. Cross-piece 37 has a radially-projecting tooth 38 (FIG. 3) integral with it on one side at one end and projecting outside of the head 33, and a spring 39 (FIGS. 4, 5) at the opposite end thereof and also outside of the head 33 normally urges the tooth to a horizontal and outer position away from the arbor. For a blank-locking or -biting action, the tooth 38 must be rotated 90° to hang downwardly and must also be pulled inwardly toward the arbor 24a, so that the free upper end of blank 11&#39; will become firmly clamped to the arbor. Dashed line-work 38&#39; (FIGS. 4, 5) characterizes the downward outer locus of the tooth 38, and dashed linework 38&#34; characterizes the inwardly-retracted position of the tooth. The reversed tooth motions must occur later, as the finished coil is released. The needed 90° rotation and inward sliding motion of toothed cross-piece 37 are both achieved by interference and camming actions as the shaped end 36 of thrust rod 32 is depressed upon actuation of piston-cylinder unit 15a. Cooperative shaping of an intermediate portion of cross-piece 37 is also involved; specifically, the cross-piece is provided with a substantially hemicylindrical cross-section, having a flat 37a as shown in FIGS. 5 and 6, and it is also provided with an oblique or sloped wedging surface 37b inclined longitudinally of the cross-piece, as shown in FIG. 5. Shaped end 36 of the thrust rod is flat on one side, 36a, where it may abut with flat 37a after its descending off-center point 36c has forced the cross-piece to turn 90°; the two abutted flat surfaces then serve to lock the cross-piece in the quarter-turned position shown by linework 38&#39;. Thereafter, further downward thrust of rod end 36 results in wedging or camming of its laterally-inclined edge 36b with the complementarily-inclined oblique surface 37b of the cross-piece, whereupon the cross-piece is wedge longitudinally to move the tooth 38 to the position 38&#34; where it bites and locks the end of blank 11&#39; with the arbor so long as the thrust rod end 36 is held in its fully-depressed position shown by dashed linework 36&#39; (FIGS. 5 and 6). Needed locking forces are maintained with little power, and variations in thicknesses of the blanks are accommodated as the thrust rod merely descends until it can move no further in that direction. 
     It is also important that a blank being picked up at the loading site be restrained and oriented at its tail end, more remote from the arbor of a work station. In particular, the tail end of each blank must be prevented from being pulled upwardly, and must be prevented from turning with the arbor as it attempts to wrap a blank about itself as a coil, and must be held at an angle of inclination appropriate to the winding of a coil with a specific pitch. For such purposes, each work station is supplied with a guide rail, 39a et seq., extending radially outward in relation to the carrousel axis 18--18 and supported at an appropriate adjustable angle relative to the horizontal by a triangular gusset plate, 40a et seq., which is adjustable in relation to a frame-supported plate 41 (FIG. 4) by way of bolts 42 (FIGS. 3 and 4) fitting loosely in one of the abutted plates. The angular adjustment thus afforded in one which affects pitch of the helically-wound coils, and is therefore an important feature when such pitch variations are to be accommodated. The guide rails 39a et seq., carry slidable locking mechanisms, 43a et seq., which have bodies 44a et seq. interfitting therewith and which therefore can move from radially outer positions, to which they are biased by a coiled cable and return-spring mechanism, 43a et seq., disposed at the radially outer ends of the guide rails. Each of the slidable locking mechanisms mounted on the bodies 44a et seq. is essentially a &#34;toggle&#34; device which will grip and hold the rear lower end of a blank as the loading onto a work station takes place. One of the elements of each toggle device is a lower jaw member, 46 (FIGS. 3, 4, 7), which is in a normally-open lowered position to begin with, and therefore allows the lower edge 11b&#39; of a blank to clear it as a blank is being approached by a work station (FIG. 4) and enables the lower rear side of the blank to abut with a horizontal tungsten-carbide tooth 47 which is the effective part of a second jaw. Thereafter, as the work station continues to turn, the roller 48 of an actuating link rides up a stationary cam surface 49 at the site of the loading installation 14 (FIG. 4) and is moved to a &#34;closed&#34; position, as shown in FIG. 7, where the pivoted link 50 pushes the cooperating link 51 and thereby forces the lower jaw member 46 both backwardly and upwardly. In the course of that &#34;toggle&#34; action, the tungsten-carbide horizontal tooth 52 of lower jaw member 46 bites the front side of the blank, at an offset position slightly above that at which tooth 47 makes its bite, such that their joint bite (FIG. 7) is tightened as any force tends to pull the blank upwardly. Jaw member 46 also provides a horizontal rest and guide for the bottom edge of the blank just before the jaw teeth complete their bite. The over-center toggle mechanism tends to hold itself locked closed until the blank has been nearly fully wound upon the arbor, at which point the coiling action tends to draw the blank material substantially radially and horizontally through the jaws and horizontal teeth, with relatively little resistance being offered by the teeth. Once the blank is thus withdrawn, the lower jaw is free and then drops under influence of gravity, and links 50 and 51 and roller 48 return to their initial positions (FIG. 4), in readiness for loading of another blank as the work station thereafter returns to the site of installation 14. The slidable locking mechanism will have been drawn radially inward along its cooperating guide rail until it is close to the arbor, before the tail end of the blank is withdrawn horizontally from between the jaw teeth, a condition shown in FIG. 9 in dashed linework, and at work station 15d in FIG. 2. Upon thus becoming free from its locking, the slidable locking mechanism is pulled to its radially outermost position once again, by the cable and coiled return-spring mechanism 45a. 
     As soon as a blank is picked up and locked both to the arbor and the tail-locking mechanism, coiling commences around the arbor, due to rotation of the latter attendant upon traversal of the stationary ring gear by the arbor pinion gear. Preferably, the blanks are coiled about the slightly-tapered arbors while simultaneously being &#34;ironed&#34; or stretch-formed by side plates 53a et seq. and 54a et seq. The latter pairs of side plates are held by movable shoes 53a&#39; et seq. and 54a&#39; et seq. and 54a&#39; et seq. which are tiltable about upper pivots 55 and 56 (FIGS. 4 and 8), the tilting being required so that the plates may be withdrawn or retracted from the finished coils to allow the latter to be released from the arbors. Each cooperating pair of ironing shoes, with side plates, is actuated by another toggle-type assembly involving links 57, 58 (FIG. 8) between their lower ends and a common circular plate, 59. As shown in FIG. 8, and in FIG. 3, the further toggle assembly is in dashed linework, because hidden behind the framework 13&#39; of the carrousel. Three rollers, 60,61 and 62, support plate 59 for limited angular movements induced by its lever-arm extension and a rod 63 actuated by a double-acting piston-cylinder unit such as units 64c and 65d in FIG. 2. In the working condition, with the side plates closed to the positions marked by dashed linework 53a&#34; and 54a&#34; in FIG. 8, the actuating links 57 and 58 are disposed substantially horizontally and diametrically opposite one another, where they can most readily withstand the &#34;ironing&#34; loadings. Turned slightly counter-clockwise, upon lifting of rod 63 to the upper position shown for piston-cylinder unit 64d in FIG. 2, the links 57 and 58 turn to the positions 57&#39; and 58&#39; shown in FIG. 8 and draw the shoes and ironing plates apart, so that a helical coil which has been wound and ironed between them may be allowed to drop off the arbor (not shown in FIG. 8, to promote clarity). The shoes and plates are drawn together just as soon as coil winding commences, and this occurs as the result of a switch, 65a et seq., on each work-station frame being actuated by its lever arm, 66a et seq., as the latter rides up a stationary cam 67 disposed near the loading installation 14. When winding is completed, the shoes and plates are separated, as the result of the same switch having its lever arm depressed by a second stationary cam 68 disposed near a coil-discharge site, such as that of station 15d in FIG. 2. The switches 64a et seq. are of known types, pneumatic or electrical, which are suitably in control of the aforementioned actuations of the piston-cylinder units such as 64c and 64d. 
     In other embodiments, the blanks being processed may be of uniform or irregular widths, and hydraulic or electrical actuators may be used in place of the illustrated pneumatic devices, and the automatic or semi-automatic controls and detectors may be mechanical, fluid or electrical, and so forth. Accordingly, it should be understood that the specific embodiments and preferred practices described herein have been presented by way of disclosure rather than limitation, and that certain departures may be accomodated within the spirit and scope of this invention in its broader aspects and as set forth in the accompanying claims.