Abstract:
Repeatable bending angle apparatus incorporated into existing manually or pneumatically operated metal stock bending apparatus permits making a number of successive bends of metal stock having similar characteristics. A disk is rotatably mounted below the bending apparatus bending arm with its center located at the bending arm axis. The disk can be rotated and locked at any bending angle. In a first embodiment, using manual bending power, an upward extension from the disk into the bending arm path provides a stop for successive bends at identical angles. Second and third embodiments use pneumatic power. The second embodiment utilizes a spring loaded insert from the stop to give the operator an indication of where to stop the apparatus at the desired angle before the disk will be rotated by the bending arm bearing against the stop. In the third embodiment the stop mounts a valve with a spring loaded extension which shuts off air to a pneumatic pump which stops the bending arm at the same angle when the bending arm depresses the valve extension for successive bends of equal angles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a regular application filed under 35 U.S.C. §111(a) claiming priority, under 35 U.S.C. §119(e)(1), of provisional application Ser. No. 61/026,240, previously filed Feb. 5, 2008 under 35 U.S.C. §111(b). 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]    Several characteristics of metal make forming an identical bending angle in two or more metal strips or tubes using conventional bending apparatus quite difficult. One is the fact that metal must be bent beyond the desired angle because it springs back after the bending force is removed. Another complication is the fact that metals with different characteristics, such as the type of metal, the metal gage, and the metal cross-section, can each result in a different final bend angle even though initially bent to the same angle. In making bends in metal it would be desirable if successive equal angle bends could be made easily without requiring complex apparatus. Previous bending apparatus attempted to obtain identical bending angle by a stop which utilized a metal circle centered on the bending axis. Equally spaced holes around the periphery of the circle provided a location for a mating bolt. The bolt extended upward into the path of the bending arm to stop the bending arm at that angle. The problem with this approach was that the force generated by a hydraulic cylinder would damage the apparatus if the bending angle exceeded the bolt location. This problem has been overcome in the present apparatus. 
       SUMMARY OF THE INVENTION  
       [0003]    The bending apparatus used can be powered either manually by a lever or by a hydraulic cylinder. The bending apparatus described here is representative of a number of benders known in the art. The repeatable bender apparatus incorporated into this bending apparatus is arranged to make multiple identical angle bends easily using either bender power source. 
         [0004]    In the present apparatus a planar disk is used to provide an angular indicator to determine the bender arm angle. The disk is rotatably attached to the bending apparatus in a horizontal orientation by a centered cylinder mounted on the disk extending downward. The disk is mounted with its center directly below the bend axis of the bending arm. A manually adjustable two part split lock has a centered hole which mates with the cylinder for mounting the disk. This lock has an adjustment arranged to permit manually changing the spacing between the two parts of the split lock to change the grip of the lock on the cylinder. 
         [0005]    The disk has equally spaced sequentially numbered radial lines on the upper surface of the disk. An indicator attached to the bender adjacent to the periphery of the disk points to the adjacent numbered radial lines or radial fractional divisions between the lines to indicate the bend angle of the bending arm. The lines are numbered rather than specifying an angle since bending metal with different characteristics to the same angle will produce different resulting angles as indicated hereinabove. Rotating the bending to a larger number results in a larger bend angle. 
         [0006]    For a first embodiment a cylindrically shaped stop is attached to the disk periphery extending upward into the bending arm path. When the bending arm is rotated to the stop position this produces the desired bending angle. To set up a bend the lock around the cylinder attached to the disk is first released. The disk is then rotated to the required angle as indicated by the line and subdivision. A cylinder lock is then adjusted to secure the cylinder and attached disk until the force required to rotate them is greater than an operator can generate using a bending arm lever. With this arrangement, in order to make a number of equal bends in stock with similar characteristics, the operator need only reset the arm to its initial location, insert a new stock piece and then rotate the bending arm until it bears against the stop. The required line and subdivision location for the disk for any desired angle and stock with the same characteristics is first determined by trial and error. 
         [0007]    When the bending apparatus uses hydraulic power to rotate the arm, the stop arrangement must be modified and a different operating procedure used. This is necessary because the force generated by a hydraulic cylinder is always adequate to rotate the disk regardless of the disk lock adjustment. For a second embodiment the stop is modified by having a spring loaded pin mounted within a recess in the stop facing the bending arm. The angle the bending arm rotates before reaching the stop defines a second angle before the disk will be rotated by the bending arm bearing against the stop. This provides an indicated interval to the operator to avoid rotating the disk. 
         [0008]    Manual operation of the hydraulic system uses a manually operated foot valve mounted on top of the hydraulic fluid pump enclosure to control the bending arm. The foot valve controls the flow of the air from an air compressor to a hydraulic fluid pump. Pumping the hydraulic fluid extends the hydraulic cylinder to rotate the bending arm. The operator merely operates the foot control, which controls the air flow to the hydraulic fluid pump, to control the bending arm rotation. In order to obtain the desired bend angle, the operator uses the foot control to rotate the bending arm until the arm reaches the pin. Manual operation of the hydraulic system uses a manually operated foot valve mounted on top of the hydraulic fluid pump enclosure to control the bending arm. The foot valve controls the flow of the air from an air compressor to a hydraulic fluid pump. Pumping the hydraulic fluid extends the hydraulic cylinder to rotate the bending arm. The operator merely operates the foot control, which controls the air flow to the hydraulic fluid pump, to control the bending arm rotation. 
         [0009]    In order to obtain the desired bend angle, the operator uses the foot control to rotate the bending arm until the arm reaches the pin. If the bending arm completely depresses the spring loaded pin and bears against the stop, the bending arm can rotate the disk and increase the bend angle beyond the desired angle even though secured by the cylinder-disk lock. This results because the force generated hydraulically is always great enough to rotate even a locked disk. However since the cylinder can rotate within the lock there is no damage to the apparatus. If this occurs, the operator can determine if the resulting bend is too excessive and whether that part should be discarded and whether the disk must be reset to the previous angle. The above process is repeated for all subsequent parts having the same characteristics to obtain the same desired bend for every part provided. The fact that the disk can rotate with no harm to the bending apparatus eliminates the problem with the present bending apparatus. 
         [0010]    A third embodiment also uses a hydraulic cylinder to rotate the bending arm with the stop of the first embodiment replaced by a control valve. The control valve has an in-port which connects with an out-port. The control valve has a spring loaded extension which is urged outward from a mating recess in the valve toward the bending arm. When the extension is extended outward the control valve, this permits air to flow from the in-port to the out-port, but when the extension is depressed the valve will prevent air from flowing between the ports. An air compressor is connected by an air line to the input port of the control valve and the output port is connected by another air line to a hydraulic pump air connection. When the bending arm is rotated against the stop, the bending arm will depress the control valve extension into the stop. This will stop the flow of air to the hydraulic pump which will stop further rotation of the bending arm. This provides the same function that the operator did manually observing the spring loaded pin to know when to stop the bending process. This arrangement eliminates the human element and provides greater accuracy. The process of using a test part to obtain the number and any fractional subdivision and the system operation is essentially the same here as described hereinabove as previously for the first embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]      FIG. 1  is a top isometric view of the bending and repeatable bending apparatus; 
           [0012]      FIG. 2  is a bottom isomeric view of the repeatable bending apparatus for all embodiments; 
           [0013]      FIG. 3  is a top isometric view of the repeatable bending apparatus for the second embodiment; 
           [0014]      FIG. 4  is a top isometric view of a portion of the repeatable bending apparatus for the second embodiment; 
           [0015]      FIG. 5  is a top plan view of the repeatable bending apparatus for the second embodiment; 
           [0016]      FIG. 6  is a top isometric view of the bending and repeatable bending apparatus for the second embodiment; and 
           [0017]      FIG. 7  is a top view of the repeatable bending apparatus for the third embodiment and a schematic of the pneumatic power equipment; and 
           [0018]      FIG. 8  is a top isometric view of the bending and repeatable bending apparatus for the third embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    There are three embodiments which relate to the method of stopping the bend at a selected angle. In the first embodiment the bending arm is powered manually and uses a simple cylinder to stop the bending arm at the desired angle. The second embodiment is powered by a hydraulic cylinder and uses a stop with a spring loaded extension. The extension provides information indicating to the operator where to stop the bending process before the part is bent too far. The third embodiment is also powering by a hydraulic cylinder but uses a control valve to stop an air source providing power to a hydraulic pump which stops the bending arm. 
         [0020]    The first embodiment is shown in  FIG. 1 . Here bending apparatus  10  is attached to mount  12  and the repeatable angle apparatus  11  attached the bending apparatus. Support arm  16  is attached extending outward from base  14 . Bending apparatus  10  is manually operated by lever arm  18 . 
         [0021]    Lever arm  18  is attached to bending arm  20  which bends stock  21 . The end of bending arm  20  opposite to lever arm  18  and the center of forming disk  23  have aligned holes sized to receive pivot pin  22 . This permits rotating forming disk  23  and bending arm  20  around pin  22 . Forming disk  23  has a groove  23 A sized to receive a portion of the circular cross-section of cylindrical shaped stock  21 . 
         [0022]    A centered hole in angle indicator disk  24  also mates with and receives pin  22  permitting the disk to rotate around the pin. Stop  24 A, which is cylindrical in shape, is attached near the periphery of angle indicator disk  24  extending upward into the path of bending arm  20 . 
         [0023]    Stop  24 A limits the rotation of bending arm  20  to the stop location. This is required because in order to repeat a bend angle bending arm  20  must stop at the same rotation angle for each successive part. This also requires that angle indicator disk  24  be locked at this rotation angle and secured with enough force that the disk cannot be rotated manually past this angle by any force that can be exerted using lever arm  18 . Index marks  25 , and numbers described hereinafter, are used to set up apparatus  11  to make a predetermined size bend after the proper rotation angle has been determined by trial and error for a particular stock. Angle indicator disk  24  is then rotated to and locked at that angle. The lock is provided by disk lock  29  hereinafter described. 
         [0024]    Disk lock  29 , shown in  FIG. 2 , is the same for all three embodiments of the invention. Here cylinder shaped extension  28  is attached perpendicular to angle indicator disk  24  with their respective centers aligned and the extension located below the disk. The rotation of extension  28  and attached angle indicator disk  24  are locked against rotation with respect to bending apparatus  10  with a predetermined force by disk lock  29 . 
         [0025]    Disk lock  29  has a support structure  30  with a split opening  30 A on the end opposite to the attachment end extending past cylinder  28  with hole  30 B enclosing the cylinder. A split  30 A into hole  30 B permits changing the hole size. Hole  30 B is sized slideably fit around cylindrical extension  28  from angle indicator disk  24  unless the split opening  30 A is partially closed. Threaded bolt  30 C engages mating threaded hole  30 D in rod  30 E. Handle  30 F is slideably mounted through hole  30 G which extends through the end of rod  30 E. With this arrangement rotating rod  30 E using handle  30 F will change the spacing of split opening  30 A and change the gripping force of disk lock  29  on extension  28  and its attached angle indicator disk  24 . For this embodiment the gripping force provided by disk lock  29  is greater than the force that can be exerted manually against stop  24 A using lever arm  18 . 
         [0026]    Support structure  30  is attached to right angle bracket  32  by four bolts  30 H through aligned mating holes and secured by mating nuts. Right angle bracket  32  has bolts  32 A which extend through mating holes in the bracket, and pointer  34  is secured by mating nuts to attach the pointer to right angle bracket  32 . Right angle bracket  32  and pointer  34  are secured to bending arm  16  with the pointer directed to the outer edge of disk  24  to indicate the angle of bending arm  20 . 
         [0027]      FIG. 5  shows index marks  25  and numbers  25 A around the periphery of the angle indicator disk  24 . Locating pointer  34  opposite to a larger number  25 A will result in a larger bend angle. Numbers are used here rather than angles because the resulting angle for any given number will change for stock with different characteristics. To set up a predetermined angle disk lock  29 , described hereinafter, is released using handle  30 F and angle indicator disk  24  then positioned the disk at a predetermined angular location. For manual powered bending operation disk lock  29  is then tightened using handle  30 F until a gripping force greater than lever  18  can produce is produced. Any number of stock items with the same characteristics can then be bent to the same angle using this set-up. 
         [0028]      FIG. 6  shows apparatus  10  and apparatus  11  in the second embodiment with hydraulic cylinder  40 C being used to rotate bending arm  20 . For hydraulic powered bending operation disk lock  29  is still locked however this is done primarily to indicate the location of the desired bend angle, since the hydraulic power provided will always be great enough to overcome the lock. 
         [0029]    Hydraulic cylinder  40 C has a return spring to return the cylinder to the recessed position when pressure is removed.  FIG. 3  shows apparatus  11 , and  FIGS. 4 , and  5  show details of stop  24 B. 
         [0030]    The stop arrangement used in the second embodiment essentially provides an indication that the bending arm  20  is within a defined second angle adjacent to the desired first angle provided by the stop location. This defined second angle is provided by the apparatus shown in  FIG. 4 . Here stop  24 B has a hole  24 B 1  extending through stop  24 A perpendicular to its length with the portion on the end of the hole adjacent to bending arm  20  being larger than the opposite end. Head  24 B 4  is sized to slideably fit within the larger portion of hole  24 B 1 . The portion of insert  24 B adjacent to head  24 B 4  is reduced in size to accommodate coiled spring  24 B 3 . The end of hole  24 B 1  opposite to bending arm  20  and the portion of insert  24 B 2  within that portion of the hole are both reduced in size with that portion of the insert  24 B slideably engaging the adjacent portion of the insert. This prevents insert  24 B from being forced outward through than end of hole  24 B 1  by spring  24 B 3 . Insert  24 B 2 , spring  24 B 3  and hole  24 B 1  are arranged to permit slideable movement of the insert within the hole and permit head  24 B 4  to slideably move from the location shown in  FIG. 4  to a location where the outer end of head  24 B 4  is flush with hole  24 B 1 . Retainer  24 B 5  prevents spring  24 B 3  from ejecting insert  24 B 2  when bending arm  18  is not adjacent to stop  24 B. Chain  24 B 6  secures retainer  24 B 5  to stop  24 B. 
         [0031]    With this arrangement after bending arm  20  has rotated until it touches insert  24 B 2 , the arm will then compress spring  24 B 3  until head  24 B 4  is flush with the adjacent end of hole  24 B 1 . The angle that bending arm  20  travels trough from the location where bending arm  20  first touches insert  24 B 4  until head  24 B 2  is flush with hole  24 B 1  defines the second angle rotation. The location of bending arm  20  where head  24 B 4  is flush with hole  24 B 1  is the selected and locked first angle. The first angle is selected and locked using the same approach and arrangements in the second embodiment as was used in the first embodiment. The second angle interval will permit the operator to respond any time before bending arm  20  bears against stop  24  where it would begin to rotate angle indicator disk  24 . However since angle indicator disk  24  can rotate there will be no damage to any part of apparatus  10  as would occur in current bending apparatus. This second angle adjacent to the selected and locked first angle essentially gives the operator an angle interval to stop the bending arm were there is no possibility of having to reset the angle indicator disk  24 . 
         [0032]    In the third embodiment shown in  FIGS. 7 and 8 , electrically powered air compressor  38  provides compressed air to control valve  36  through air hose  38 A, and air hose  38 B provides air from the control valve to foot control assembly  40 . This contrasts with the second embodiment where air compressor  38  provides air directly to foot control assembly  40 . Essentially control valve  36  in embodiment  3  is substituted for stop  24 B in the first embodiment. As mentioned hereinabove the pneumatic powered system hydraulic cylinder  40 C requires a spring return for proper operation, which is a common configuration. Control valve  36  has a spring loaded projection  36 A facing bending arm  20 . A control valve having the required characteristics is manufactured by Pneumadyne Inc. Part No. All-30-44. When extension  36 A is extended air can flow through control valve  36  from air hose  38 A to air hose  38 B. When control valve extension  36  is depressed by bending arm  20  control valve  36  will close and prevent air from flowing from air hose  38 A to air hose  38 B which will stop the advance of bending arm  20  at that angular rotation as hereinafter described. This arrangement will also repeat the same bend angle for stock having the same characteristics until angle indicator disk  24  is rotated and control valve  36  repositioned at a different angle. 
         [0033]    Foot control assembly  40  has a base  40 A containing a hydraulic fluid storage tank and an air driven pneumatic pump controlled by the position of foot control  40 B. A foot control assembly having the required characteristics for foot control  40 B is manufactured by Shin Fu of Taiwan for BVA Hydraulics Part # PA1500. Hydraulic fluid pumped by assembly  40  is forced through hose  40 D to hydraulic cylinder  40 C. 
         [0034]    With this arrangement when bending arm  20  depresses control valve extension  36 A, the flow of air to rotate bending arm  20  will automatically stop. This will result in the same bend angle being formed successively in stock having similar characteristics. Again the location of control valve  36  can be determined by trial and error for stock with any given characteristics identical to the previous procedures used to obtain the previous stop locations. The fact that cylinder  40 C has a return spring permits resetting the cylinder by merely releasing pressure to the cylinder using foot control  40 B after the hydraulic fluid flow is stopped. 
         [0035]    Incorporating repeatable bending apparatus into conventional bending apparatus, which can be either lever or hydraulically powered, requires only simple apparatus to obtain the same angle bend for any number of successive bends of stock which have the same characteristics. The set-up is also simple requiring only rotating and locking the disk at a predetermined location relative to the disk numbers and index marks. The required disk location can easily be determined by trial and error, and once determined can be provided to the user as part of a plan. This greatly simplifies constructing apparatus requiring a number of equal angle bends in a number of similar stock pieces. 
         [0036]    The above embodiments are just a few examples of the modifications and changes that are possible and would readily occur to one skilled in the art, therefore it is contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention. 
         [0037]    It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims.