APPARATUS FOR FABRICATING CONCRETE REINFORCING STIRRUPS AND THE WELDING THEREOF WITH RODS TO FORM A CONCRETE REINFORCING CAGE

Abstract: Stirrups (8) for concrete reinforcing cages are fabricated to a required shape by feeding wire (19) through a die (21) located in a wire distribution head (22) and placing an end (18) of the wire (19) in a retaining means (17) on a matrix plate (1) and then moving the wire distribution head (22) via an actuating means (24, 25, 26, 27) in a predetermined path around a series of parallel pins (14) situated in the matrix plate (1) and then overlap, cut and weld the wire (19) to thus form a stirrup (8). Also described and claimed is a welding apparatus to combine the stirrups (8) with longitudinal rods (2) to form a concrete reinforcing cage.

Description: Apparatus for fabricating concrete reinforcing stirrups and te welding thereof with rods to form a concrete reinforcing cage This invention relates to apparatus for fabricating concrete reinforcing cages and has been devised particularly for the fabricating of concrete reinforcing stirrups and for the welding of those stirrups to longitudinal rods to form concrete reinforcing cages. BACKGROUND ΑRT In the past reinforcing cages used to reinforce concrete beams or panels used in many applications such as the footings of buildings, pillars, floor sections or concrete panels have been fabricating by bending the reinforcing wires or rods to the desired configuration and by then tying or welding the wires or rods together. Such a procedure is extremely time consuming and costly and it is therefore desirable, to provide a machine which will automatically bend and fasten together the various rods and wires required to fabricate a concrete reinforcing cage.. Attempts have been made to provide such a machine, for example as described in International Patent Specification PCT/AU82/00134 but such machines have required the prefabricating of stirrups to be fed into the machine which itself is time consuming and costly, and furthermore have incorporated components which are difficult to use or prone to fail in service. In particular such machines have incorporated conduits for the supply of current to resistance welding electrodes which have been flexible in nature and difficult to locate, insulate and cool. DISCLOSURE OF INVENTION It is therefore an object of the present invention to provide apparatus for fabricating concrete reinforcing cages which will go at least part of the way toward meeting the foregoing desiderata or which will obviate or minimise the foregoing disadvantages in a simple yet effective manner, or which will at least provide the public with a useful choice. Accordingly in one aspect the invention consists in apparatus for fabricating concrete reinforcing stirrups from wire or rod, comprising a support frame on which are mounted a plurality of substantially parallel pins protruding out of a reference plane and being located at the corners of a desired stirrup shape, wire retaining means arranged to hold one end of the wire in a desired position to commence bending of the stirrup, a wire distribution head incorporating a die adapted to receive wire from a supply thereof at right angles to the reference plane and bend the wire parallel to the reference plane as it passes through the die. and actuation means arranged to support and move the distribution head over a predetermined path parallel to the reference plane, distributing the wire from the wire retaining means around the pins and back to the wire retaining means, forming a continuous stirrup. Preferably the apparatus includes finishing means arranged to join the ends of the wire adjacent the wire retaining means, and cut the wire between the die and the joined ends. Preferably the actuation means is arranged to cause the ends of the wire to be overlapped one on top of the other adjacent the wire retaining means, and wherein the finishing means includes welding means arranged t.o weld together the overlapped ends. Preferably the finishing means includes two shearing jaws protruding out of the reference plane on either side of the overlapped wires, being provided with cutaway portions at the depth of the lower wire and shearing portions at the depth of the upper wire, and means arranged to move the two jaws together so that the lower wire is accommodated in the cutaway portions, and the upper wire is cut by the shearing portions. Preferably the welding means comprise a first electrode located beneath the overlapped wires and a second electrode located alongside the overlapped wires, together with a conducting bridge movable toward and away from the reference plane so that when the conducting bridge is moved toward the reference plane one arm of the bridge contacts the second electrode and the other arm of the bridge contacts the uppermost of the overlapped wires directly above the first electrode so that when a voltage is applied across the electrodes currrent passes through the bridge and through the overlapped wires, resistance welding the overlapped wires together. Preferably the support frame comprises a backing plate in the reference plane with the pins protruding outwardly from the backing plate. Preferably the actuation means arranged to support and move the distribution head comprise hydraulic rams mounted on the backing plate and controlled by preprogrammed control means. Preferably the die incorporated in the distribution head has a passage therethrough at right angles to the reference plane, the passage terminating in a bell mouth at the end of the die adjacent the reference plane. Preferably the backing plate is divided into two sections movable relative to one another in the reference plane, selected ones of the pins being located in one section and the remaining pins being located in the other section so that the pins in one section may be moved toward the pins in the other section after formation of a stirrup around the pins, allowing easy release of the stirrup from the pins. In a further aspect the invention consists in an apparatus for welding a stirrup into a matrix of longitudinal rods forming a concrete reinforcing cage, said apparatus comprising a plurality of electrodes adapted to be positioned in pairs within the perimeter of the stirrup in contact with the stirrup wire so that each electrode is located on the opposite side of the stirrup wire from a longitudinal rod, and a plurality of electrically conducting bridges movable toward and away from the longitudinal rods and arranged such that each bridge may be moved into contact with a pair of rods located on the opposite side of the stirrup wire from a corresponding said pair of electrodes. whereupon a voltage may be applied across each said pair of electrodes causing current to flow from one electrode, through the stirrup wire and the longitudinal rod adjacent thereto, into the corresponding bridge, through the bridge to the other rod of the pair and thence through the stirrup wire to the other of the pair of electrodes, causing the stirrup wire to be resistance welded to the longitudinal rods. Preferably the longitudinal rods are located by being passed through selected holes in a matrix plate under tension, and the bridges are movable toward and away from the longitudinal rods in the plane of the stirrup by hydraulic rams mounted on the matrix plate. Preferably the electrodes are formed on two metal electrode plates, the first plate being located in the plane of the stirrup and having peripheral portions extending into contact with the stirrup and forming one of each pair of electrodes, and the second plate being spaced from but parallel to the first plate and having projections therefrom into the plane of the first plate in those regions between the said peripheral portions on the first plate, the projections forming the other of each pair of electrodes and the two plates being insulated from one another. Preferably the electrode plates are mounted on the matrix plate and current is supplied to the electrode plates by conductors passing through the matrix plate from a position immediately behind the electrode plates. Preferably the overall periphery of the first plate and the projections from the second plate, substantially conforms with the inner periphery of the stirrup, so that the stirrup may be placed over and located by the two plates before welding. BRIEF DESCRIPTION OF DRAWINGS Notwithstanding any other forms that may fall within its scope, one preferred form of the invention will now be described by way of example only with reference to the accompanying drawings, in which:- Fig. 1 is an overall perspective view of apparatus for fabricating concrete reinforcing cages according to the invention; Fig. 2 is a perspective scrap view of the apparatus for fabricating concrete reinforcing stirrups incorporated in the apparatus shown in Fig. 2; Fig. 3 is a transverse section through the welding apparatus incorporated in the apparatus shown in Fig. 2; Fig. 4 is a perspective view of the transfer mechanism arranged to transfer stirrups fabricated by the apparatus shown in Fig. 2 into the cage formed by the longitudinal rods; Fig. 5 is a perspective view of the electrode plates used in the welding of the stirrups to the longitudinal rods; Fig. 6 is an elevation of the electrode plates shown in Fig. 5 when engaged with a stirrup and longitudinal rods; an Fig. 7 is a sectional elevation through the apparatus shown in Fig. 6. at right angles to the Fig. 6 elevation. MODES FOR CARRYING OUT THE INVENTION In the preferred form of the invention apparatus for fabricating concrete welding cages is constructed as follows with reference to Fig. 1. The apparatus comprises a vertical matrix plate (1) having a plurality of holes therethrough arranged to locate a plurality of longitudinal rods (2) which pass through the plate from supply coils (3) by way of straighteners (4). The rods are pulled through the holes in the matrix plate (1) under tension by way of pawls (5) incorporated in a frame (6) movable by a hydraulic ram (7). The apparatus is designed to weld transverse stirrups (8) to the longitudinal rods (2) as will be described below, and the pawls (5) engage behind each stirrup so welded in turn to pull the longitudinal rods through the matrix plate (1). Once the cage so fabricated has reached its desired length it is cut to size by a guilotine (9) incorporating a number of pairs of shearing jaws (10) [one pair for each longitudinal rod]. The apparatus for fabricating concrete reinforcing cages is provided with apparatus for fabricating stirrups to go in those cages shown generally at (11). The apparatus is also provided with apparatus for welding the stirrups into the matrix shown generally at (12). The stirrup forming apparatus will now be more particularly described with reference to Figs. 2 to 4, and the welding apparatus with reference to Figs. 5 to 7. The stirrup fabricating apparatus is mounted on the matrix plate (1) [Fig. 2] which defines a reference plane for the apparatus. The matrix plate has a number of holes therethrough, examples of which are shown at (13) and pins (14) are engaged in selected ones of the holes (13) so as to protrude out of the matrix plate, the pins being located at the corners of a desired stirrup shape. The apparatus shown in Fig. 2 is set up for the formation of a simple rectangular stirrup having four external corners, but it will be appreciated that the apparatus can be used to form stirrups of any desired configuration, incorporating re-entrant corners if required. Selected ones of the pins (14) are mounted directly in the matrix plate CD and others of the pins are mounted in a separate portion (15) of the matrix plate, which is coplanar with the main portion (1) but which is movable relative to the main portion as shown by arrows (16). By virtue of this movement the lower two pins shown in Fig. 2 may be moved closer to the upper two pins by upward movement of the portion (15). releasing the stirrup from the pins after fabrication as will be described further below. The apparatus is further provided with wire retaining means in the form of vice jaws (17) protruding through the matrix plate (1) and actuable by a hydraulic ram assembly behind the matrix plate so as to grasp the free end (18) of the wire from which the stirrup is to be formed. The wire (19) is provided from a coil (20) [Fig. 1] and is directed toward the matrix plate (1) at right angles to the plate by way of a die (21) located in a wire distribution head (22). The die has a passage therethrough at right angles to the matrix plate (1) terminating in a bell mouth at the end of the die adjacent the reference plane. The distribution head is supported and located by the piston rod (23) of a hydraulic ram (24) which is located in a plane parallel to the matrix plate (1) and mounted to that plate by way of a pivot pin (25) [Fig. 1] for movement in that plane. The rotational movement of the hydraulic ram (24) about the pivot pin (25) is controlled by a second hydraulic ram (26) engaging the first ram by way of a yoke (27). The operation of the two hydraulic rams (24) and (26) is controlled by preprogrammed control means [e.g. numerical or computer control means] to position and locate the distribution head (22) anywhere over the matrix of pins (14) supported by the matrix plate (1). In this manner once the end of the wire has been grasped in the wire retaining vice (17), the distribution head may be moved over the desired shape of the stirrup, causing the wire (19) to be drawn through the die (21). turned at right angles through the bell mouth of the die. and laid against the matrix plate (1) around the pins (14) in the desired shape. Once the distribution head has made a complete circuit around the pins (14) back to the end (18) of the wire, the head is moved slightly outwardly away from the matrix plate (1) and then continues its movement over the wire already placed causing an overlap of the wire at (28) adjacent to the wire retaining jaws (17). In this location there are provided a pair of welding electrodes (29) and (30), most clearly seen in Fig. 3 and which protrude through the matrix plate separated by insulator (31) so that the end of the electrode (29) abuts against the lower portion (32) of the overlapped wires. The welding apparatus further comprises a conducting bridge (33) mounted on the distribution head (22) by way of a hydraulic ram (34) for movement toward and away from the matrix plate (1). Once the stirrup has been formed by overlapping the wire portions (35) and (32) to form the overlap (28), the conducting bridge (33) is moved towards the matrix plate as shown by arrow (36) under operation of the hydraulic ram (34) causing one arm (37) of the bridge to contact the electrode (30) and the other arm (38) to contact the uppermost overlapped wire portion (35). In this manner a circuit is completed from the first electrode (29) through the lower wire (32), the upper wire (35) and the bridge (33) to the other electrode (30). When a voltage is applied across the electrodes (29) and (30) current passes between the wire portions (32) and (35), resistance welding the two wire portions together. Once the welding operation has been completed the bridge (33) is retracted by the hydraulic ram (34) and the upper portion of the overlapped wires cut between the weld and the distribution head (22). The cutting operation is performed by shearing means in the form of two shearing jaws (39) protruding through the matrix plate (1) on either side of the overlapped wires. The shearing jaws are provided with cutaway portions at the depth of the lower wire (32) and shearing portions at the depth of the upper wire (35) so that when the jaws are moved together by a hydraulic ram on the opposite side of the matrix plate (1) the lower wire is accommodated in the cutaway portions and the upper wire is cut by the shearing portions. In this manner a completed stirrup is bent up around the pins (14), the ends are welded together, and the wire extending from the distribution head (22) is cut. The distribution head (22) is then retracted by the hydraulic ram (24). the pins (14) are moved together by movement of the plate portion (15) as described previously, the vice jaws (17) are opened, and the stirrup may then be removed from the pins to be welded in place in the reinforcing cage. Once the stirrup has been removed as described below, the distribution head is re-positioned to engage the recently cut end of the wire (18) in the vice (17) and the operation repeated to produce another stirrup. The completed stirrup is picked up from the pins (14) by a transfer arm (40) [Fig. 4] mounted for transverse movement on guide rods (41) by way of a carriage (42) controlled by a hydraulic ram (43) mounted on the matrix plate (1). Jaws (44) are mounted on the lower end of the arm (40) operable by a hydraulic or electrical mechanism (45) to grip the stirrup (46), preferably at the position of the overlapped welded wires. Once the stirrup located on the pins (14) has been so gripped, the arm is rotated outwardly away from the matrix plate (1) by an actuating member (47) to move the jaws (44) through an arc shown by arrow (48), and then moved transversely as shown by arrow (50) by operation of hydraulic ram (43) to locate the stirrup inside the cage of longitudinal rods (2), whereupon the actuator (47) is again operated to move the jawa as shown by arrow (51) to locate the stirrup over the welding electrode plates as will now be described. The welding apparatus (12) comprises a plurality of electrodes adapted to be positioned in pairs within the perimeter of the stirrup in contact with the stirrup wire so that each electrode is located on the opposite side of the stirrup wire from a longitudinal rod. To this end the electrodes are formed on two metal electrode plates (52) and (53) [Figs. 5 to 7], the first plate (52) being located in the plane of the stirrup (54) placed over the plates by the transfer mechanism shown in Fig. 4, and the second plate (53) being spaced from but parallel to the first plate and separated therefrom by insulation (55). The first plate (52) has peripheral portions (56) extending into contact with the stirrup (54) and forming one of each pair of electrodes. The second plate (53) has projections therefrom (57) into the plane of the first plate in those regions between the peripheral portions (56) of the first plate. The projections (57) form the other of each pair of electrodes. Where necessary the periphery of the peripheral portions (56) of the first plate may be built up in the location of the longitudinal rods as shown at (58) [Fig. 5] to provide a superior contact between the electrode plate (52) and the stirrup wire (54) in the location of the longitudinal rods during the welding process described below. The welding apparatus is further provided with a plurality of electrically conducting bridges (59) [Fig. 6] which are positioned and movable by hydraulic rams (60) supported by the matrix plate (1). The overall layout of the welding electrodes (52) and (53), the bridges (59) and the hydraulic rams (60) can be clearly seen in Fig. 1. The bridges (59) are located so that each bridge may be moved into contact with a pair of rods (2) located on the opposite side of the stirrup wire from a corresponding pair of electrodes (56, 57), by the operation of the hydraulic rams. When the bridges (59) are moved into this position as shown in Fig. 6 and voltage is applied across the electrode plates (52) and (53), current is caused to flow from the plate (52) through the peripheral portions (56) to the stirrup wire (54) and the longitudinal rods (61), passing through the bridges (59), the longitudinal rods (62) and the stirrup wire (54) back to the projections (57) on the second plate (53) completing the electrical circuit . The current passing through the junction between the longitudinal rods (2) and the stirrup wire (54) causes the stirrup wire to be welded to the longitudinal rods in those locations by • resistance welding. Once the welding has been completed the bridges (59) are withdrawn by the hydraulic rams (60) and the cage may be advanced by pulling the longitudinal rods (2) through the matrix plate (1) under the action of the pawls (5) in the frame (6) actuated by the hydraulic ram (7). Once the cage has been advanced by the desired spacing between stirrups, a further stirrup is inserted into the cage by the transfer arm (40) and the welding operation is repeated. Where it is desired to form a reinforcing cage having an odd number of longitudinal rods, it is possible to form one of the electrode plates with a portion outside of the stirrup perimeter and arrange one bridge to contact both that portion and one rod which is located immediately adjacent an electrode formed on the other plate. In this manner apparatus is provided which enables the fully automatic fabrication of concrete reinforcing cages from supplies of rod or wire such as reels (3) and (20). Furthermore the apparatus has the advantage that cages of any desired cross section may be fabricated by placing the longitudinal rods through selected holes in the matrix plate (1) and positioning the pins (14) in the required location for the bending up of a stirrup of the desired shape. The program controlling the hydraulic rams (24) and (26) is adjusted to move the distribution head (22) in the desired path to form the wire (19) into the desired stirrup shape around the pins (14). The welding apparatus (12) has the particular advantage that current may be supplied to the electrode plates (52) and (53) by way of conductors (63) and (64) from the opposite side of the matrix plate (1) so that there is no requirement for loose or flexible conductors to be located on the "operational" side of the matrix plate where they could be damaged by the operation of the fabrication apparatus.

Claims: CLAIMS:- 1. Apparatus for fabricating concrete reinforcing stirrups from wire or rod, comprising a support frame on which are mounted a plurality of substantially parallel pins protruding out of a reference plane and being located at the corners of a desired stirrup shape, wire retaining means arranged to hold one end of the wire in a desired position, to commence bending of the stirrup, a wire distribution head incorporating a die adapted to receive wire from a supply thereof at right angles to the reference plane and bend the wire parallel to the reference plane as it passes through the die, and actuation means arranged to support and move the distribution head over a predetermined path parallel to the reference plane, distributing the wire from the wire retaining means around the pins and back to the wire retaining means, forming a continuous stirrup. 2. Apparatus as claimed in claim 1 including finishing means arranged to join the ends of the wire adjacent the wire retaining means, and cut the wire between the die and the joined ends. 3. Apparatus as claimed in claim 2 wherein the actuation means is arranged to cause the ends of the wire to be overlapped one on top of the other adjacent the wire retaining means, and wherein the finishing means includes welding means arranged to weld together the overlapped ends. 4. Apparatus as claimed in claim 3 wherein the finishing means includes shearing means arranged to shear or cut the overlapped wire between the weld and the distribution head. 5. Apparatus as claimed in claim 4 wherein the shearing means comprise two shearing jaws protruding out of the reference plane on either side of the overlapped wires, and being provided with cutaway portions at the depth of the lower wire and shearing portions at the depth of the upper wire, and means arranged to move the two jaws together so that the lower wire is accommodated in the cutaway portions, and the upper wire is cut by the shearing portions. 6. Apparatus as claimed in claim 3 wherein the welding means comprise a first electrode located beneath the overlapped wires and a second electrode located alongside the overlapped wires, together with a conducting bridge movable toward and away from the reference plane so that when the conducting bridge is moved toward reference plane one arm of the bridge contacts the second electrode and the other arm of the bridge contacts the uppermost of the overlapped wires directly above the first electrode so that when a voltage is applied across the electrodes current passes through the bridge and through the overlapped wires, resistance welding the two wires together. 7. Apparatus as claimed in claim wherein the welding bridge is operable for movement toward and away from the reference plane by a fluid actuated piston and cylinder assembly mounted on the distribution head. 8. Apparatus as claimed in any one of the preceding claims wherein the said actuation means arranged to support and move the distribution head comprise hydraulic rams controlled by preprogrammed control means. 9. Apparatus as claimed in claim 8 wherein the said hydraulic rams comprise a first ram arranged parallel to the reference plane, having the distribution head mounted on one end thereof and being pivotally mounted on a portion at the opposite end for movement in a plane parallel to the reference plane, and a second ram in the same plane arranged to rotate the first ram about the said pivot pin. so that combined operation of the first and second hydraulic rams in a predetermined manner can position the distribution head anywhere over the matrix of pins supported by the support frame. 10. Apparatus as claimed in any one of the preceding claims wherein the die incorporated in the distribution head has a passage therethrough at right angles to the reference plane, the passage terminating in a bell mouth at the end of the die adjacent the reference plane. 11. Apparatus as claimed in any one of the preceding claims wherein the support frame comprises a backing plate in the reference plane, with the pins protruding outwardly from the backing plate. 12. Apparatus as claimed in claim 11 wherein the backing plate is divided into two sections movable relative to one another in the reference plane, selected ones of the pins being located in one section and the remaining pins being located in the other section so that the pins in one section may be moved toward the pins in the other section after formation of a stirrup around the pins, allowing easy release of the stirrup from the pins. 13. Apparatus as claimed in claim 11 when dependent upon claim 9 wherein the hydraulic rams are mounted on the backing plate. 14. Apparatus as claimed in any one of the preceding claims including a transfer mechanism arranged to pick up a completed stirrup from the pins and transfer that stirrup into a predetermined position in a cage of longitudinal rods for the welding of the stirrup into that cage. 15. Apparatus for welding a stirrup into a matrix of longitudinal rods forming a concrete reinforcing cage, said apparatus comprising a plurality of electrodes adapted to be positioned in pairs within the perimeter of the stirrup in contact with the stirrup wire so that each electrode is located on the opposite side of the stirrup wire from a longitudinal rod. and a plurality of electrically conducting bridges movable toward and away from the longitudinal rods and arranged such that each bridge may be moved into contact with a pair of rods located on the opposite side of stirrup wire from a corresponding said pair of electrodes, whereupon a voltage may be applied across each said pair of electrodes causing current to flow from one electrode, through the stirrup wire and the longitudinal rod adjacent thereto into the corresponding bridge, through the bridge to the other rod of the pair and thence through the stirrup wire to the other of the pair of electrodes, causing the stirrup wire to be resistance welded to the longitudinal rods. 16. Apparatus as claimed in claim 15 wherein the bridges are movable toward and away from the longitudinal rods in the plane of the stirrup by hydraulic rams. 17. Apparatus as claimed in either claim 15 or 16 wherein the electrodes are formed on two metal electrode plates, the first plate being located in the plane of the stirrup and having peripheral portions extending into contact with the stirrup and forming one of each pair of electrodes, and the second plate being spaced from but parallel to the first plate and having projections therefrom into the plane of the first plate in those regions between the said peripheral portions on the first plate, the projections forming the other of each pair of electrodes, the two plates being insulated from one another. 18. Apparatus as claimed in claim 17 wherein the overall periphery of the first plate and the projections from the second plate, substantially conforms with the inner perimeter of the stirrup, so that the stirrup may be placed over and located by the periphery of the two plates before welding. 19. Apparatus as claimed in either claim 17 or claim 18 wherein the longitudinal rods are located by being passed through selected holes in a matrix plate under tension, and wherein the electrode plates are mounted on the matrix plate. 20. Apparatus as claimed in claim 19 wherein electrical current is supplied to the electrode plates by conductors passing through the matrix plate from a position immediately behind the electrode plates. 21. Apparatus as claimed in claim 19 when dependent upon claim 2 wherein the hydraulic rams locating and controlling the bridges are supported by the matrix plate.

Inventors: BRUCE HOWARD, BRUCE, HOWARD
Applicants: BRUCE HOWARD, BRUCE, HOWARD
Application year: 1985
Main classification: B21D11
IPC codes: B21F1, B21F27, B21F31, B23K11