Abstract:
A rectangular tubing bender having a frame provided with an arrangement for locking in place a tube to be bent. Structure on the frame forms directly opposed depressions on opposite sides of the rectangular tube prior to bending of the tube adjacent the depressions for permitting a completely closed and square bend to be formed. The locking arrangement may be mounted on a carriage movable on the frame for bending the tube by moving same against a stationary forming point member subsequent to the formation of the depressions in the tube. Cam operated rockers are advantageously employed to form the depressions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is related generally to the bending of tubing, and particularly to the formation of bends in rectangular tubing, and the like, that are completely closed and square on the inside of the bend. 
     2. Description of the Prior Art 
     Conventional devices commonly employed for forming right-angle and similar bends in metal tubing having a rectangular cross section form an open bend which decreases the strength and rigidity of the element and makes it difficult to weld at the inside corner of the tube at the bend therein in order to additionally strengthen the bent tube. 
     Prior U.S. Pat. Nos. believed pertinent to this invention are as follows: 
     
         1,816,218        July 28, 19312,148,748        Feb. 28, 19392,516,372        July 25, 19502,835,306        May 20, 19583,042,099        July 3, 19623,073,372        Jan. 15, 19633,240,048        Mar. 15, 19663,472,055        Oct. 14, 1969 
    
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide rectangular tubing with completely closed and square bends for forming a more rigid, stronger bend, and making it possible to weld the inside corner of the bend for additional strength. 
     It is another object of the present invention to provide for the bending of rectangular tubing, and the like, in a simple, efficient and consistent manner. 
     These and other objects are achieved according to the present invention by bends formed by first depressing, or dimpling, a section of a tube to be bent on two opposing sides thereof to form directly opposed dimples in the tube; then moving the dimpled tube toward a forming point; and bending the dimpled tube on the forming point. 
     Apparatus according to the present invention for forming the aforementioned bends includes: a frame; a holding arrangement for locking a rectangular tube to be bent in place on the frame; a squeezing arrangement for forming the depressions on opposite sides of the tube; and a forming member for bending the tube about the depressions formed therein. 
     The holding arrangement advantageously includes a carriage mounted on the frame for reciprocal movement with respect to the frame, and a support member mounted on the carriage. The support member includes a pair of substantially parallel, opposed, spaced flanges connected together by a web, with the flanges being arranged for receiving between them a tube to be bent. 
     The forming arrangement advantageously further includes a forming point member affixed to the frame and arranged for cooperating with the support member to bend a tube to be bent. Accordingly, the holding arrangement preferably further includes drive means for sequentially moving the carriage toward the forming point member. 
     A preferred embodiment of the squeezing arrangement includes a pair of rockers pivotally mounted about substantially parallel axes on the carriage whereby each rocker is provided with a pair of arms. A squeezing jaw is mounted on a one arm of a rocker, and a cam follower is mounted on the other of the arms. The jaws and cam followers of the rockers are arranged in opposed relationship to one another, and cams, which may be in the form of ramps mounted on the forming point member, operatively engage the cam followers and pivot the jaws towards one another for forming the depressions in the tube. 
     The holding arrangement preferably further includes a pair of plates arranged bracketing the support member, and a pair of lock arms are pivotally mounted on the carriage for selectively engaging the plates and preventing same from spreading apart as the cam followers contact the cam following ramps referred to above. In this manner, the tube being bent is securely held on the carriage as the various operations are being performed on the tube. 
     These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing a tubing bender according to the present invention. 
     FIG. 2 is a fragmentary, sectional view taken generally along the line 2--2 of FIG. 1. 
     FIG. 3 is a fragmentary, perspective view showing a detail of the device of FIGS. 1 and 2. 
     FIG. 4 is a fragmentary, top plan view showing the detail of FIG. 3, but with the parts thereof in a moved position. 
     FIG. 5 is a fragmentary, vertical, longitudinal sectional view, similar to FIG. 2, but showing certain parts in a moved position from FIG. 2. 
     FIG. 6 is a fragmentary, top plan view, partly broken away, similar to FIG. 4, but showing certain parts thereof in a moved position from their position in FIG. 4. 
     FIG. 7 is a fragmentary, sectional view taken generally along the line 7--7 in FIG. 5. 
     FIGS. 8, 9, and 10 are fragmentary, perspective views showing the sequence of steps in forming a bend in rectangular tubing in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 of the drawings shows a rectangular tubing bender 10 according to the present invention which includes a frame 12 provided with an arrangement 14 for holding a tube 16 of rectangular cross section. A squeezing arrangement 18 is also provided on frame 12 for forming depressions, or dimples, on opposite sides of tube 16 prior to bending of the tube 16 by means of a forming arrangement 20. The tube is bent about the previously formed depressions in a manner to be described in greater detail below. 
     Referring now more particularly to FIGS. 2 through 4 of the drawings, arrangement 14 includes a carriage 22 slidably mounted on frame 12 for reciprocal movement with respect to the frame. A support member 24 is mounted on carriage 22, and includes a pair of substantially parallel, opposed, spaced flanges 26 and 28 connected together by a web 30. Flanges 26, 28 are arranged for receiving therebetween tube 16. 
     Arrangement 20 advantageously further includes a forming point member 32 affixed to frame 12 in a conventional manner and arranged for cooperating with support member 24 to bend tube 16. Toward this end, arrangement 14 further includes a drive motor 34, which is advantageously the illustrated linear fluid motor, connected to carriage 22 as by piston rod 36 for sequentially moving carriage 22 toward forming point member 32. As will be appreciated, motor 34 will also retract carriage 22 from the proximity of member 32. 
     Squeezing arrangement 18 advantageously includes a pair of rockers 38 and 40 pivotally mounted on carriage 22 for pivoting about suitable axles such as the illustrated pins 42 and 44. As can be readily appreciated from, for example, FIG. 2 of the drawings, rockers 38 and 40 are pivotally mounted on pins 42, 44 at points on the rockers between the ends of same for providing each rocker with a pair of arms. Squeezing jaws 46 and 48 are mounted on one arm of the rockers, while cam followers 50, 52 are mounted on the other arm of the rockers. Jaws 46, 48 and cam followers 50, 52 are arranged opposite one another for operatively engaging a pair of oppositely directed ramps affixed to the forming point member 32 and forming cams that pivot the jaws 46, 48 toward one another and cause them to form the depressions in tube 16. 
     Arrangement 14 still further includes a pair of plates 58 and 60, which may have the generally diamond-shaped configuration best seen perhaps in FIG. 4 of the drawings, arranged bracketing support member 24. The free end of piston rod 36 of motor 34 is pivotally connected to plates 58, 60 as by a conventional hinge 62. A pair of lock arms 64 and 66 are pivotally mounted on carriage 22 for selectively engaging plates 58 and 60 and preventing same from spreading apart as cam followers 50, 52 engage the cam forming ramps 54 and 56. A crank 68 is affixed to a shaft 70 to which arms 64 and 66 are also affixed. Shaft 70 is pivotally mounted in suitable brackets 72 as can be seen from FIG. 7 of the drawings. Coiled torsion springs 74 are associated with brackets 72 in a conventional manner for retaining arms 64 and 66 in their upright, or locking, position as shown in FIG. 3 of the drawings. A pin 76 is provided projecting from a beam 78 partially forming frame 12 for engaging crank 68 when carriage 22 is in a retracted position, as shown in FIGS. 2 and 4 of the drawings, and swinging arms 64 and 66 into the position shown in FIG. 2 for arm 66. This position is an inoperative position of the lock arms 64, 66 which permits the tube 16 to be removed from, and another tube placed into, support member 24. Notches 80 are provided in arms 64 and 66 for permitting the arms to positively engage plates 58 and 60 and prevent the plates from spreading. Further, notches 82 are provided in arms 64, 66 for mating with tubes 16 as can best be seen from FIG. 5 of the drawings. 
     Referring again to FIG. 7 of the drawings, frame 12 further includes a pair of angles 84 and 86 forming spaced, substantially parallel, side rails of the frame. Beam 78 and a similar beam 88 are attached to the respective angles 84 and 86. As can best be seen from FIG. 3, a cutout portion 89 is provided in angle 86 for receiving crank 68. A plate 90 is attached to brackets 72, which in turn slide beneath beams 78 and 88, and is provided with a pair of projections 92 and 94 which journal shaft 70. As also can best be seen from FIG. 7, rocker 40 is provided with a pair of spaced, substantially parallel portions 96 and 98 which receive cam follower 52. The latter is rotatably mounted on a rod 100 journaled in portions 96 and 98. It will be appreciated that rocker 38 is constructed in a similar manner. 
     Point member 32 is advantageously mounted in a conventional manner, such as by the illustrated bolt, to a crossbar 102 which is arranged extending between the beams 78 and 88. Grooves 104 and 106 are provided in point member 32 extending longitudinally away from the ramps 54 and 56 for forming a guide path for the cam followers 50, 52 and permitting the followers to move toward one another a distance sufficient to assure that the jaws 46 and 48 will clear tube 16 once the depressions have been made in the tube. 
     Guides 108 and 110, which are advantageously in the form of metal plates, and the like, are desirably provided in those portions of beams 78 and 88 traversed by carriage 22. In this manner, the lower surface of plate 60 and the uppermost portion of brackets 72 will act as slides which permit the carriage 22 to be moved in a rigid and stable manner along frame 12. 
     As best seen from FIGS. 1 and 3 of the drawings, an installation is provided which includes a crossbar 112 and beams 114 and 116 extending cantilever fashion perpendicular to bar 112 for supporting a curved rail 118 that prevents the tubing from dropping as the bend is being made. This also eliminates placing undue stress on the machine. Curved rail 118 has associated therewith a pair of guide bars 120 and 121 upon which the tube 60 is arranged prior to its being bent. A fixed stop 122 is arranged at the outermost end of guide bar 121, while an adjustable stop and alignment assembly 124 is provided for positioning tubing being bent to allow for varying placement of the bends. Assembly 124 is mounted on guide bar 121 in a manner that permits it to be adjusted along the length of the bar. This mounting may be achieved as by a conventional clamp mounting of the assembly, which mounting is shown schematically in FIG. 1. 
     Referring again to FIG. 1, a conventional electric motor 126, and the like, is connected to a conventional source of electric power (not shown) to actuate a conventional fluid pump 128. The output of pump 128 is situated through hoses 130 and 132 to motor 34 for the purpose of actuating same. A linkage 134 connects in a conventional manner an operator&#39;s handle 136 to the conventional control mechanism (not shown) of pump 128. In this manner, an operator (not shown) may actuate motor 34 by manipulation of handle 136 in a known manner. 
     As can best be seen from FIGS. 4 and 6 of the drawings, support member 24 is divided into a pair of similar portions 138 and 140. Each of these portions 138, 140 is pivotally mounted between plates 58 and 60 as by pins 142 and 144 which may be in the form of the illustrated bolts. Further, each of the portions 138 and 140 has a flange 26, 28 and a connecting web 30. Thus, when tube 16 is bent by engagement therewith against point member 32, portions 138 and 140 will be swung around pins 142 and 144 to a position forming a substantial V-shape as is shown in FIG. 6. When tube 16 is first placed within support member 24, however, the webs 30 will be parallel to tube 16 as is seen in FIG. 4. 
     OPERATION 
     The operation of a bender 10 according to the present invention will now be described with reference to FIGS. 5, 6, and 8 through 10 of the drawings. 
     A tube 16 is initially loaded into support member 24 with the carriage 22, and lock arms 64 and 66, in the positions shown in FIG. 2 of the drawings. Motor 34 is now actuated and carriage 22 is fed toward forming point member 32. When carriage 22 has traversed toward point member 32 sufficiently to permit the cam followers 50 and 52 to engage their associated ramps 54 and 56, as shown in FIG. 5, jaws 46 and 48 will be brought toward one another by a pivoting movement of rockers 38 and 40 about their associated pins 42 and 44, and a pair of directly opposed depressions 146 will be formed in opposite walls of tube 16. These depressions are advantageously substantially in the transverse center portion of the associated walls of the tube. As carriage 22 continues its movement to the right as seen in FIG. 5, cam followers 50 and 52 will fall into their associated grooves 104 and 106, an extreme position of which is shown in FIG. 6 of the drawings. When the cam followers 50, 52 pass into grooves 104, 106, carriage 22 will have moved sufficiently far to the right as viewed in FIG. 5 to cause the V-shaped point of forming point member 32 to engage tube 16 at a point immediately adjacent the depressions and in a wall adjacent the forming member 32 and perpendicular to the walls in which the depressions were made. It will be appreciated that once the cam followers 50, 52 pass into grooves 104, 106 jaws 46, 48 will be released from tube 16. Contact of tube 16 with forming point 32 will cause the tube to start to bend as is seen in FIG. 8. Continued movement of carriage 22 toward the right in FIG. 5 will cause additional bending of tube 16, as is shown in, for example, FIG. 9. Both depressed sides of tube 16 bend inward as the bending proceeds. Further, the area where the forming point member 32 contacts tubing 16 also bends inwardly. This is apparent from FIG. 9. As tube 16 is bent further, the bend on the inside of the tubing forces forming point member 32 out of the inside bend, thus allowing completion of the bend as shown in FIGS. 6 and 10 of the drawings. In this manner, a bend is formed which is closed and square on the inside 148 of the bend, thus making it possible to weld the inside corner of the bend for additional strength. 
     The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.