US3137921A - Method of forming a sectional, stamped metal hold-down anchor device for the cables of prestressed concrete girders - Google Patents

Description

June 23, 1964 B. HILLBERG 3,137,921

METHOD OF FORMING A SECTIONAL, STAMPED METAL HOLD-DOWN ANCHOR DEVICE FOR THE CABLES OF PRESTRESSED CONCRETE GIRDERS Filed July 31, 1961 3 Sheets-Sheet l June 23. 1964 B. HILLBERG 3,137,921

METHOD OF FORMING A SECTIONAL, STAMPED META HOLD-DOWN ANCHOR DEVICE FOR THE CABLES OF PRESTRESSED CONCRETE GIRDERS Filed July 31, 1961 3 Sheets-Sheet 2 I44 I 44 A 4 I33 134 41 I I33 8190/? H/LL8ER6, DSC54560 By EMMA H/LLJERG, EXEC/170R JEAN ELIZABETH ALI A5", EXECUTOA CONTINENTAL ILL/N045 Alli/d/VIL 5411/1; 7/?067' Call/ 41V);

June 23, 1 964 B. HILLBERG 3,137,921 METHOD OF FORMING A SECTIONAL, STAMPED METAL HOLD-DOWN ANCHOR DEVICE FOR THE CABLES 0F PRESTRESSED CONCRETE GIRDERS Fil ed July 51, 1961 3 Sheets-Sheet 3 INVENTOR aka? mums-ea, DECEASED y MMA H/LLBERG, EXECUTOR JEAN L/ZA5E7'l-l 44 ws, sxzcurap CU/Yf/NEN/ZL MAM/0M NAT/0174i 844 4 Til/8T COMPANY, LIL BY United States Patent METHOD 0F FGRMING A SECTIONAL, STAMPED METAL HQLD-DGWN ANCHOR DEVICE FOR THE CABLES 0F PRESTRESED CQNQRETE GIRDERS Bror Hillherg, deceased, late of Elmwood Park, 11]., by Emma Hillherg and Jean Elizabeth Alvis, executrices, Wheaton, Ill., and Continental Illinois National Bank and Trust Company of Chicago, executor, Chicago, 151., assignors to Superior Concrete Accessories, Inc, a corporation of Delaware Filed July 31, 1961, Ser. No. 130,223 2 Claims. (6!. 29l5h) The present invention relates to hold-down anchor devices of the type which is shown and described in my copending patent application Serial No. 130,222, filed on July 31, 1961 and entitled Sectional Hold-Down Anchor Devices for the Embedded Cables of Prestressed Concrete Girders. The invention has particular reference to a method of forming the sheet metal stampings which cooperate to make up such hold-down anchor devices.

In the aforementioned patent application, there has been disclosed a composite sectional hold-down anchor device by means of which certain of the cables which extend through a concrete girder, for example a girder having the cross-sectional configuration of an I-beam, from one end thereof to the other for prestressing purposes are held taut and under a considerable degree of tension in the concrete girder form preparatory to and during concrete pouring operations. Reference may be had to such copending patent application for a full disclosure of the hold-down anchor device and of the manner in which it is used in connection with such a form. However, to facilitate an understanding of the present invention, it may be stated briefly that the hold-down anchor device with which the present method is concerned consists essentially, insofar as its overall configuration is concerned, of an elongated central tubular hub from which there extends outwardly and radially in opposite directions a pair of coplanar side wings. These side wings are provided with series of spaced notches which extend inwardly from the outer edges of the side wings and at an acute angle with respect to the longitudinal axis of the hub so that when the hold-down anchor device is operatively positioned within a concrete girder form, each notch may receive therein one of the cables to be tensioned with the vectorial force of the tensioned cable bearing upwardly against the inner or bottom edge of the notch. The holddown anchor device may initially be applied to the cables before the latter are tensioned, and thereafter the device may be pulled down or pushed down into position within the form to apply tension to the cables; The device is then held or maintained in such position until after the concrete has been poured and has become set or hardened. Alternatively, the hold-down anchor device may initially be secured in position within the form, the cables then threaded through the inclined notches by slipping them endwise into the notches, and finally the cables may be tensioned to draw them taut. With any one of these methods of installation and use, and particularly tubular hub facilitates installation of the hold-down anchor device in the form inasmuch as it may form a guide bore for either a pulled down or a pushed down cable, or a lag bolt by means of which the device may be bolted to the base of the concrete girder form, all in a manner clearly set forth in the aforementioned copending patent application.

In order to enable the hold-down anchor device to be progressively built up to any desired length from a number of stocked parts at the factory, the hub and its notched side Wings are formed from individual sections which are in the form of sheet metal stampings, each section including a half-hub and a pair of coplanar radially extending side wing fragments. Thus, by positioning one of these sections or stampings against another such section or stamping, with the two half-hubs thereof in registry and with the side wing fragments in face-to-face contact, a complete hub or a longitudinal section of a complete hub will be formed as will the two complete side wings or longitudinal portions thereof. The stampings are made in two lengths, namely, a full unit length stamping and a half-unit length stamping. The side wing fragments of the full unit length stampings are provided with two notches conformable in size and shape and orientation to the size, shape and orientation of the notches in the complete side wing, while the half-unit length stampings have single notches in the side wing fragments thereof. The arrangement is such that any number of pairs of cable strands may be accommodated. For example, two cable strands may be accommodated by assembling two of the half-unit length stampings upon each other; four cable lengths may be accommodated by assembling two of the full unit length starnpings; six cable strands may be accommodated by assembling two of the full unit length stampings upon each other with only one pair of notches in register and with one-half of each stamping overhanging an end of the other stamping and thereafter positioning half-unit length stampings at the opposite ends of the device and at opposite sides of a medial plane to complete the hub and side wings in the regions where the overhang takes place. The previously mentioned curved bevels on each side of the side wings of the completed article are formed in the individual stampings so that when these stampings are assembled upon one another, the bevels are paired on the opposite sides of the notches in the bottom edge regions thereof.

with the last mentioned method wherein the cables are It is among the principal objectsof the present invention to provide a novel method of forming either the full unit length. stampings or the half-unit length stampings, as described above, utilizing the same series of forming dies and involving only three stamping operations, the resultant stamping issuing from these operations being complete in every respect and requiring no machining or other metal-removing operations prior to assembly of the parts to produce the finished hold-down anchor device.

It is a still further object of the invention to provide such a method wherein by such stamping operations the stampings are formed from a flat sheet metal blank and wherein after the first stamping operation has been completed, the half-hub portion is displaced from the general plane of the metallic sheet so that it may thereafter serve as a pilot recess for piloting cooperation with a pilot pro tuberance on'certaiu of the dies subsequently employed to hold the partially completed stampings in position within the die structures which are involved during the remaining forming or stamping operations.

A still further object of the invention is to provide such a method wherein the previously mentioned notches which are formed in the side wing fragments of the stampings undergoing formation have their bottom edge regions intially fashioned by a combined punching and coining operation after which in a succeeding step the side edges of the notches are formed in proper register with the previously formed notch bottoms to produce the completed notches. By the provision of such a step, a more uniform notch is attained in each instance than wouldbe possible where conventional methods of proclucing acurved bevelled area around the bottom of a notch are employed. 7 r

With these and other objects in view which will become more readily apparent as the nature of the present method is better understood, the same consists in the novel steps which have been illustrated in the accompanying three sheets of drawings forming a part of this specification.

In these-drawings:

FIG. 1 is a side elevational view, partly in section, showing operatively assembled in a concrete girder form an assembled hold-down anchor device consisting of parts or stampings which are constructed according to the present method;

FIG. 2 is an exploded perspective view showing the parts of the hold-down anchor device of FIG. 1 operatively juxtapositioned for assembly upon one another to complete the device;

FIG. 3 is a sectional view taken on the line 33 of FIG. 1;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4;

FIG. 6 is a schematic view showing a series of forming dies in end elevation and in register with a strip of sheet metal to be operated upon, and also showing in perspective two preformed blank shapes, either of which may result from the use of the forming dies;

FIG. 7 is a schematic view similar to FIG. 6 but showing a pair of forming dies for operating upon either of the formed blank shapes of FIG. 6;

FIG. 8 is a schematic view similar to FIGS. 6 and 7 showing a pair of shearing, shaping and coining dies for operating upon either of the blank shapes of FIG. 7;

FIG. 9 is a sectional view taken on the line 99 of FIG. 7; and

FIG. 10 is a sectional view taken on the line 1010 of FIG. 8.

In the above described views, similar characters of reference have been employed to designate similar contours through out regardless of whether these contours appear in the completed hold-down anchor device, in the partially completed stampings, or in the fully completed stampings which cooperate to make up the hold-down anchor device.

Referring now to the drawings in detail and in particular to FIGS. 1, 3 and 4 inclusive, one of a number of composite hold-down anchor devices of varying lengths, the individual parts of which are capable of being constructed according to the present method, has been designated in its entirety by the reference numeral 10. The device is comprised of four individual sheet metal stampings which may be assembled upon one another in various ways to produce any desired length of hold-down anchor device and thereafter welded together to complete the device. The specific nature of these stampings will be made clear presently. In the form of the invention illustrated herein for exemplary purposes, the hold-down anchor device is adapted to accommodate the tensioning of six cable strands such as the strands shown at 12.

Considering only the outline or configuration of the device 10 as a whole, without relation to its component parts, the device includes a central tubular hub portion 14 of elongated design and having an internal bore 16 extending longitudinally therethrough. Projecting outwardly and radially from opposite sides of the hub portion 14 and in opposite directions are a pair of flat coplanar side wings 18. Each of these side wings 18 has formed therein a series of three vertically spaced notches 20 and they extend inwardly from and at an acute angle d to their side wing. As shown in the drawings the notches are inclined downwardly and outwardly. Each notch 20 is provided with straight parallel side edges 22 and a semicircular inner or bottom edge 24 and is adapted to receive edgewise therein one of the cable strands 14 as clearly shown in FIGS. 1 and 4 so that when the strands are tensioned they will exert an upward pressure on the bottom edges 24 of the notches. In order to reduce frictional forces and prevent damage to the cable strands 12 when the latter are drawn taut, the bottom edge 24 of each notch 21} is bevelled on a curved bias as indicated at 26.

The hold-down anchor device 10 is adapted to be secured within a concrete girder form in various Ways and one manner of anchoring the device in position has been shown in FIG. 1 wherein a lag bolt 34 extends upwardly through a hole 31 in the base member 32 of the concrete girder form and extends completely through the bore 16. The upper end of the lag bolt receives thereon a clamping nut 34 by means of which the lower end of the device is forced downwardly against a spacing collar 36 which is seated on the base member 32.

As previously stated, the hold-down anchor device 10 comprises four principal parts. These parts are best illustrated in FIG. 2 and they include two full unit length stampings 5t) and two half-unit length stampings 52, hereinafter referred to simply as full length and halflength stampings respectively. The two full length stampings 50 are identical and each includes a half-hub 54 and a pair of oppositely extending coplanar side wing fragments 56. Each side wing fragment 56 is formed with a pair of vertically spaced notches which in the assembled device create the side wing notches 21) of FIGS. 1 and 4. The half-length stampings 52 include a halfhub 60 and oppositely directed side wing fragments 62. Each side wing fragment 62 is formed with a single notch conforming in size and shape to the notches in the side wings 18 of the assembled device.

The various side wing fragments 56 and 62 of the full length stampings 50 and of the half-length stampings 52 are further provided with a series of locating holes 70 and locating protuberances 72, the disposition of such holes and protuberances being such that the various stampings 50 and 52 may be assembled upon one another in several diiferent ways so that the protuberances of one stamping will extend into the holes of another stamping and vice versa In my heretofore mentioned copending patent application, a description of how these various stampings may selectively be fitted together to produce anchor devices of varying selected lengths has been set forth. In the present instance, the two full length stampings 50 and the two half-length stampings 52 are shown in FIG. 2 as being juxtapositioned for subsequent assembly upon one another to produce the anchor device 10 of FIG. 1. The assembly is effected by bringing the halfhubs 54 and the side wing fragments 56 together to produce the full hub 14 and side wings 18 with one-half of each stamping 50 overhanging one-half of the other stamping in a longitudinal direction. Thereafter, the half-length stampings 52 are moved into contact with the overhanging portions of the full length stampings 50 to complete the hub 14 and side wings 18. Finally, welding heat and pressure are applied to the thus positioned side wing fragments in the vicinity of the various interlocking holes 70 and protuberances 72 to effect permanent union of the parts. After the assembly has been made, each notch in the side wing fragments 62 of each half-length stamping 52 will register with a notch in a side wing fragment 56 of a full length stamping, while two of the notches associated with each full length stamping 50 will register with two other notches in the other full length stamping.

Referring now to FIGS. 6 to 10, inclusive, wherein the method of forming the stampings 50 and 52 has been illustrated schematically, a pair of first step dies and 102 are shown in FIG. 6 for operating upon a blank 104 to produce the shape 106. The shape 106 is then operated upon by a pair of second step dies 108 and 110 (see FIG. 7) to produce the shape 112. The shape 112 is then transferred to a pair of third step dies 114 and 116 (see FIG. 8) and the shape 50 (which is the full length stamping) is produced. Alternatively, and as will be described subsequently, the various dies 100, 102, 100, 110, 114 and 116 are capable of producing half-unit length shapes leading to the production of the half-length stamping 52 as shown in FIG. 8.

Referring now to FIG. 6, the upper die 100 has on its operating surface a semi-circular rib 120 which, in combination with a semi-cylindrical trough 122 in the lower die 102, produces the half-hub 54. The upper die 100 also has a pair of flat side surfaces 124 which, in combination with similar side surfaces 126 on the lower die 102, produce in the blank 104 the side wing fragments 56. If a half-length blank (not shown) is appropriately placed in the dies 100, 102, the resultant shape will be the shape indicated at 130 which includes the half-hub 60 and the side wing fragments 62.

The shape 106 is then transferred to the pair of dies 108 and 110 shown in FIG. 7 in an inverted relationship. A series of four combined shearing and coining punches 132 having coining surfaces 133 and shearing edges 134 is provided on the working surface of the upper die 108 and cooperates with corresponding series of mating bores 135 in the lower die 110 to produce a series of four holes 136 in the previously formed side wing fragments 56 of the shape 106, as well as to displace the metal in the upper rim regions of the holes 136 as indicated at 138 to produce a generally rounded continuous bevelled surface surrounding these holes. The four holes 136 are formed in the side wing fragments 56 precisely at the places where the bottom edges or regions of the notches occur in the finished full length stamping 50 and a portion of the coined or displaced regions 138 ultimately constituting the curved, bevelled regions 26 on one side of the various notches in the finished stamping 50. The upper die 108 is also formed on its operating surface with a series of punches 140 which cooperates with a corresponding series of bores 142 in the lower die 110 to produce the various holes 70 in the side Wing fragments 56. A series of protuberances 144 on the working surface of the upper die 108 cooperates with a corresponding series of depressions 146 in the working surface of the lower die 110 to produce the protuberances 72 in the side wing fragments 56.

It is to be noted that the half-hub 54 of the shape 106 fits against and is centered in saddle-like fashion over a rib 150 on the working surface of the lower die 110 so as to maintain the shape 106 as a whole properly centered on the die 110 for cooperation with the die 108. A relief groove 152 affords clearance for the half-hub 54.

In connection with the formation of a blank halflength stamping 52, the blank for such stamping after being formed is properly positioned in the die structure consisting of the second step dies 108 and 110 and onehalf of each die is utilized to produce the half-length shape 130 of FIG. 6.

Referring now to FIG. 8, after the full length shape 112 has been completed, it is positioned for cooperation with the third step dies 114 and 116. The lower die 116 is provided with a semi-cylindrical rib 154 over which the half-hub 54 of the shape 112 extends and on which it is seated in saddle-like fashion in order properly to align the shape 112 with the die 114. A clearance 156 in the upper die 114 receives the protuberance 154 and the half-hub 54 when the dies are closed upon each other. The upper die 114 is formed with a series of four raised shearing ribs 160 on opposite sides of the working face thereof (see also FIG. Each of these ribs has parallel sides 162 and a curved inner end 164. The ribs 160 extend inwardly from the opposite longitudinal sides of the die and they are conformable to the size and shape of the notches 20. The disposition of'these shearing ribs 160 is such that the inner curved ends 164 thereof register with portions of the circular rims of the holes 136. The radius of curvature of the curved ends 164 is precisely equal to the radius of the holes 136 exclusive of the bevelled areas 138 so that when the upper die 114 descends upon the lower die 116 to form the notches 20 in the completed or finished stamping 50, some of the metal on one side of each hole 136 is removed from the shape 112, together with the adjacent portions of the curved bevels 138 but the remaining portions of the bevels are not disturbed so that these portions appear as at 26 in the finished stamping 50. Stated in other words, the shear ing ribs 160 serve to create in the shape 112 notches which intersect the holes 136 in the side wing fragments 56 so that portions of the circular edges of the holes, including the associated curved bevels, are cut away while other portions are allowed to remain intact and constitute the predeterminedly shaped bevelled bottom edges of the completed notches in the stamping 50.

The operation of the dies 114 and 116 on the halflength shapes is substantially the same as that set forth above in connection with the full length shapes 112, only one pair of shearing ribs at one end of the die 114 being used. To facilitate alignment of the shapes 130 with the two shearing ribs 160, the two dies 114 and 116 may be formed with vertically registering sockets and 172 respectively. The socket 172 is adapted to receive therein a removable locating pin 174 such as has been shown in dotted lines while the other socket 172 constitutes a clearance void for the pin 174.

It will be understood that the disclosures of FIGS. 6 to 10 inclusive are schematic in their representation and the various die instrumentalities portrayed in these views are not necessarily exact representations of the actual dies which may be employed in constructing the various shapes leading up to the formation of the stampings 50 and 52. For example, the various pairs of upper and lower dies may have associated therewith suitable pilot stems and cooperating recesses and various other accessory instrumentalities if desired. Other die arrangements are contemplated for performing the method steps outlined above and even the method steps themselves may be varied within certain limits. For example, by causing the protuberances 144 and depressions 146 to be associated with the dies 114 and 116 instead of the dies 108 and 110, the forming operations performed thereby may be effected at a later step in the process. Therefore, only insofar as the invention has particularly been defined in the accompanying claims is the same to be limited.

Having thus described the invention what is claimed as new is:

l. The method of making a hold-down anchor device of the type having a central tubular hub from which there extend outwardly in radial fashion in opposite directions from the opposite sides thereof a pair of flat side wings each of which is formed with a cable-receiving notch therein extending inwardly from its outer edge, the bottom edge of the notch being semi-circular with the opposite rims of the notch along the semi-circular bottom edge thereof being relieved on a curved bias to enhance the anti-frictional characteristics of a cable strand undergoing axial sliding movement through the notch, said method comprising utilizing a first pair of forming dies to deform the medial region of a flat rectangular metal blank between the longitudinal side edges thereof and produce a semi-cylindrical half-hub from which there extend outwardly in radial fashion in opposite directions from the longitudinal edges of the half-hub a pair of flat side wing fragments; utilizing a second pair of forming dies to punch a circular hole in each of said side wing fragments and, in the same operation, coin the rim of the hole which is on the side of the fragment from which the half-hub projects and thus produce a closed bevelled surface completely encompassing the hole on such side;

utilizing a third pair of forming dies to shear from each 'of the thus punched side wing fragments a strip of metal which spans the distance between the outer edge of the side wing fragment and the hole in such fragment and in-' cludes a portion of the edge of the hole and the adjacent portion of the bevelled surface, thus producing in the side wing fragment a notch which has for its bottom edge that portion of the edge of the hole remaining in the side wing fragment after the shearing operation; similarly deforming, punching, coining and shearing a second and identical flat rectangular metal blank; assembling the two shapes resulting from such deforming, punching, coining and shearing operations by juxtapositioning said shapes with their semi-cylindrical half-hubs in opposed relation ship to form a cylindrical hub, with their side wing fragments in face-to-face contact, and with the notches of the side wing fragments in register; and finally fixedly conmeeting the two shapes together in such juxtapositioned relationship.

2. The method of making a hold-down anchor device of the type having a central tubular hub from which there extend outwardly in radial fashion in opposite directions from the opposite sides thereof a pair of flat side wings each of which is formed with a cable-receiving notch therein extending inwardly from its outeredge, the bottom edge of the notch being semi-circular with the opposite rims of the notch along the semi-circular bottom edge thereof being relieved on a curved bias to enhance the anti-frictional characteristics of a cable strand undergoing axial sliding movement through the notch, said method comprising: utilizing a first pair of forming dies to deform the medial region of a flat rectangular metal blank between the longitudinal side edges thereof and produce a semi-cylindrical half-hub from which there extend outwardly in radial fashion in opposite directions from the longitudinal edges of the half-hub a pair of fiat side wing fragments; utilizing a second pair of forming dies to punch a circular hole in each of said wing fragments and, in the same operation, coin the rim of the hole which is on the side of the fragment from which the half-hub projects and thus produce a closed bevelled surface completely encompassing the hole on such side; utilizing a third pair of forming dies to shear from each of the thus punched side wing fragments a strip of metal which spans the distance between the outer edge of the side wing fragment and the hole in such fragment, has parallel straight side edges, is equal in width to the outside diameter of the closed bevelled surface encompassing the punched hole, and includes a portion of the edge of the hole and the adjacent portion of the bevelled surface, thus producing in the side wing fragment a notch which has for its bottom edge that portion of the edge of the hole remaining in the side wing fragment after the shearing operation; similarly deforming, punching, coining and shearing'a second and identical flat rectangular metal blank; assembling the two shapes resulting from such deforming, punching, coining and'shearing operations by juxtapositioning said shapes with their semi-cylindrical half-hubs in opposed relationship to form a cylindrical hub, with their side wing fragments in face-to-face contact, and with the notches of the side wing fragments in register; and finally fixedly connecting the two shapes together in such juxtapositioned relationship.

References Qited in the file of this patent UNITED STATES PATENTS 1,917,322 Peirce July 11, 1933 2,287,182 Leake June 23, 1942 2,822,146 Ridgers et al. Feb. 4, 1958

Claims (1)

1. THE METHOD OF MAKING A HOLD-DOWN ANCHOR DEVICE OF THE TYPE HAVING A CENTRAL TUBULAR HUB FROM WHICH THERE EXTEND OUTWARDLY IN RADIAL FASHION IN OPPOSITE DIRECTIONS FROM THE OPPOSITE SIDES THEREOF A PAIR OF FLAT SIDE WINGS EACH OF WHICH IS FORMED WITH A CABLE-RECEIVING NOTCH THEREIN EXTENDING INWARDLY FROM ITS OUTER EDGE, THE BOTTOM EDGE OF THE NOTCH BEING SEMI-CIRCULAR WITH THE OPPOSITE RIMS OF THE NOTCH ALONG THE SEMI-CIRCULAR BOTTOM EDGE THEREOF BEING RELIEVED ON A CURVED BIAS TO ENHANCE THE ANTI-FRICTIONAL CHARACTERISTICS OF A CABLE STRAND UNDERGOING AXIAL SLIDING MOVEMENT THROUGH THE NOTCH, SAID METHOD COMPRISING UTILIZING A FIRST PAIR OF FORMING DIES TO DEFORM THE MEDIAL REGION OF A FLAT RECTANGULAR METAL BLANK BETWEEN THE LONGITUDINAL SIDE EDGES THEREOF AND PRODUCE A SEMI-CYLINDRICAL HALF-HUB FROM WHICH THERE EXTEND OUTWARDLY IN RADIAL FASHION IN OPPOSITE DIRECTIONS FROM THE LONGITUDINAL EDGES OF THE HALF-HUB A PAIR OF FLAT SIDE WING FRAGMENTS; UTILIZING A SECOND PAIR OF FORMING DIES TO PUNCH A CIRCULAR HOLE IN EACH OF SAID SIDE WING FRAGMENTS AND, IN THE SAME OPERATION, COIN THE RIM OF THE HOLE WHICH IS ON THE SIDE OF THE FRAGMENT FROM WHICH THE HALF-HUB PROJECTS AND THUS PRODUCE A CLOSED BEVELLED SUR-

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