Portable sheet bending brake

A portable sheet bending brake comprising a first member defining a clamping surface extending longitudinally, a second member extending longitudinally and hinged to the fixed member, and an anvil member extending longitudinally of the sheet bending brake that is moved into and out of clamping position with the fixed member. A floating compensator comprising a compensator member is pivoted to the bending member and a workpiece engaging pad is pivoted to the compensator member such that as the bending member is swung to bend a workpiece, the pad engages the surface of the workpiece and remains in contact with the workpiece at the same area by the relative pivotal action of the bending member, the compensator member and the pad.

This invention relates to sheet bending brakes and particularly to portable 
sheet bending brakes. 
BACKGROUND AND SUMMARY OF THE INVENTION 
In the handling of sheet material such as is used for building 
construction, it has been common in recent times to provide a portable 
sheet bending brake wherein sheet material is clamped between an anvil 
member and a clamping surface and a bending member is hinged for bending 
the sheet material about the anvil member. Typical sheet bending brakes 
are disclosed in U.S. Pat. Nos. 3,161,223, 3,481,174, 3,482,427, 
3,559,444, 3,187,075 and 4,240,279. 
As shown, for example, in the aforementioned U.S. Pat. Nos. 3,161,223, 
3,559,444, 3,817,075 and 4,240,279, the anvil member is clamped into 
position by means of a backing plate that has inclined cams underlying a 
portion of the fixed frame so that when the plate is moved longitudinally 
by a hand lever, the cams are moved into and out of position clamping and 
unclamping the backing plate. 
In the aforementioned U.S. Pat. Nos. 3,481,174 and 3,482,427, the anvil is 
supported by pivoted bars that, in turn, are connected by links to a 
handle that is pivoted on the frame of the brake so that rotation of the 
handle moves the bars and, in turn, the anvil into and out of clamping 
position. 
It has also heretofore been suggested that eccentric cams be utilized for 
moving the anvil member into and out of position as shown, for example, in 
U.S. Pat. Nos. 3,383,899, 4,092,841 and 4,081,986. 
In the aforementioned U.S. Pat. Nos. 3,481,174 and 3,482,427, a floating 
compensator has been pivoted on the bending member such that the 
compensator engages an area of the workpiece and remains in engagement 
with the same area so that the workpiece is not marred or scuffed during 
the bending. Such an arrangement has proved very effective in portable 
sheet bending brakes. However, as the bending member approaches and 
exceeds a position for making a bend of 90.degree. or greater, the area of 
application of force on the workpiece shifts radially inwardly so that the 
bending arm or lever is less and a greater force is required to move the 
bending member. In addition, there may be a tendency for the force to be 
concentrated on less than the total area of the compensator. 
Among the objectives of the present invention an to provide a portable 
sheet metal bending brake which includes an improved floating compensator 
which remains in contact with a greater area than the compensator of U.S. 
Pat. Nos. 3,481,174 and 3,482,427; which requires a lesser force to move 
the bending member, especially when the workpiece is bent to greater 
angles; and which permits a second and tighter bend to be performed 
without clamping the workpiece. 
In accordance with the invention, the hinged bending member is provided 
with a floating compensator that comprises a compensator member pivoted to 
the bending member and a workpiece engaging pad pivot to the compensator 
member. As the bending member is swung to bend a workpiece, the pad 
engages the surface of the workpiece and remains in contact with the 
workpiece at the same area by the relative pivotal action of the bending 
member, the compensator member and the pad.

DESCRIPTION 
Referring to FIGS. 1, 2 and 3, the portable sheet bending brake embodying 
the invention comprises a plurality of longitudinally spaced C-shaped 
frame members 10 which are made of metal such as cast aluminum or 
injection molded of reinforced plastic such as 30% glass filled nylon. 
Each frame member 10 includes a lower arm 11 and an upper arm 12 with a 
connecting portion 13, the upper arm 12 being shorter than the lower arm 
11. Each frame member 10 includes a rearwardly extending recess or notch 
14 for receiving an extruded aluminum square rear rail 15. As shown in 
FIG. 2, portion 13 includes laterally extending flanges 16 overlying the 
upper surface of the rear rail 15 through which screws 17 extend to fasten 
the rear rail 15 to the frame members. 
A first fixed extruded aluminum member 20 is provided on the front end of 
the lower arms 11 as presently described and comprises an upper generally 
triangular portion 21 defining a horizontal clamping surface 22 and a 
lower C-shaped portion 23 that has upper and lower walls that telescope 
over the free ends of the lower arms 11. Screws fasten the fixed member 20 
on the arms 11. 
An extruded aluminum bending member 24 is hinged to a portion of the fixed 
member 20 by a continuous hinge defined by intermeshing projections on the 
members 24, 20, respectively. A hinge pin extends through aligned openings 
in the projections to complete the hinge. The bending member 24 further 
includes a laterally extending L-shaped portion 25 that receives the lower 
end of an extruded floating compensator 26 yieldingly urged by a spring 27 
against the hinge. The member 26 engages the sheet to be bent and 
minimizes marring during the bending as more fully described in U.S. Pat. 
Nos. 3,481,174 and 3,482,427 which are incorporated herein by reference. 
The bending member 24 further includes a tubular operating handle 28. 
The sheet bending brake further includes a plurality of extruded aluminum 
bars 30, a bar 30 being pivoted to each frame member 10 by a bolt 31 at 
the area of juncture of the rear of the arm 12 and the upper part of the 
connecting portion 13. Each bar 30 includes an upper flange 32, a lower 
flange 33, and a vertical wall 34. An extruded aluminum shaft 35 is 
journalled in the forward ends of the upper arms 12 by plastic bearings 
and extend through enlarged openings in the vertical walls of the bars 30. 
A plurality of plastic eccentric cams 36 are fixed on shaft 35 so that 
they are positioned between the upper and lower flanges 32, 33 of each 
bar. 
The bars 30 support an anvil member 37 that includes an upper horizontal 
portion bolted to the lower flange 33 of the bars, and inclined portion 
and a V-shaped nose portion having a horizontal bottom surface and an 
inclined upper surface. As shown in FIG. 2, a protective strip 38 of sheet 
metal such as rolled stainless steel is provided. 
The shaft and eccentric cams are rotatably adjustable relative to one 
another. More specifically, the shaft and eccentric cams are provided with 
circumferentially spaced teeth extending axially so that the cams are 
locked in any adjusted position. The position of a cam can be adjusted by 
moving the cam axially relative to the shaft to disengage the teeth on the 
cam from the teeth on the shaft, rotating the cam to the desired adjusted 
position and moving the cam axially to reengage the teeth. 
The sheet bending brake heretofore described is substantially like that 
described in the aforementioned U.S. application Ser. No. 423,459 filed 
Sept. 24, 1982, which is incorporated herein by reference. 
The floating compensator 26 comprises a compensator member 40 pivoted to 
the bending member 24 and a workpiece engaging pad 41 pivoted to the 
compensator member 40. Compensator member 40 and pad 41 extend 
longitudinally throughout the length of the bending member 24 and fixed 
member 20. As the bending member 24 is swung to bend a workpiece S, the 
pad 41 engages the surface of the workpiece and remains in contact with 
the workpiece at the same area by the relative pivotal action of the 
bending member 24, the compensator member 40 and the pad 41. 
More specifically, the compensator member 40 comprises an extrusion, the 
upper and lower ends 42, 43 of which are formed with arcuate cylindrically 
shaped surfaces, respectively. The lower end 42 engages an upwardly facing 
cylindrical recess 44 in the bending member 24. The upper end 43 engages a 
cylindrical recess 45 in the pad 41. Compensator member 40 further 
includes a retaining lip 46 that cooperates with a lip 47 on the bending 
member 24. Similarly, pad 41 includes a lip 48 that normally contacts 
compensator member 40 when the compensator pad is out of contact with the 
workpiece. The upper surface 49 of pad 41 is flat to provide maximum 
contact with the workpiece. 
As shown in FIG. 2, before engagement with the workpiece, the upper surface 
49 of pad 41 is inclined with respect to the clamped workpiece so that 
there is full contact by pivoting action of the pad when it engages the 
workpiece. 
After a workpiece has been clamped in position for bending by swinging 
handle 40, the handle 28 is used to swing the bending member 24 to bend 
the workpiece. The pad 41 engages the workpiece and remains in contact 
with the entire portion of the same area of the workpiece during the 
entire bending operation, FIG. 4. This is assured due to the relative 
pivotal action of the bending member 24, compensator member 40 and pad 41. 
In the modified compensator 26a shown in FIG. 5, the compensator member 40a 
is provided with a lop 50 which cooperates with lip 49a on pad 41a to 
assist in the retention of pad 41a on the compensator member 40a. 
The compensator 26 embodying the invention permits making a tighter bend 
after the first bend. Thus, if the workpiece is bent so that the bent 
portion contacts the upper surface of strip 38, the bent workpiece can be 
unclamped and laid on the upper surface of strip 38. The bending member is 
then moved to bring pad 41 into engagement with the workpiece further 
bending the workpiece to provide two substantially parallel contacting 
portions.