Abstract:
A bending brake for sheet material includes frames; an upper jaw and a lower jaw that cooperate to hold the sheet material a bending surface pivotally connected to the lower jaw to bend the sheet material against an anvil of the upper jaw; an interlocking unit connected to the frame and having a cam surface which has having a locking position; and an elongated pipe assembly for rotation by a user. The elongated body bears against the cam surface and rests in the locking position to clamp the sheet material with reduced freedom of play.

Description:
RELATED APPLICATIONS  
       [0001]     The present invention is a non-provisional counterpart to and claims priority from U.S. 60/641,497 filed on Jan. 5, 2005, which is hereby incorporated by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention is directed to portable construction equipment, and more particularly, to sheet bending brakes.  
         [0004]     2. Background  
         [0005]     The use of some machines calls for supporting a workpiece while presenting it with a particular orientation to the machine. For example, a common bending machine, known as a sheet bending brake (“brake”), is operative to bend a substantially flat workpiece of sheet material. Such sheet material typically are made of aluminum, one or more compositions of vinyl, or the like and are used in siding structures, houses, railings or the like.  
         [0006]     In order to bend such a workpiece using a typical sheet bending brake, ordinarily, the workpiece is first positioned upon the brake&#39;s clamping surface so that the edges of the workpiece have a desired orientation with respect to the brake. Commonly, a rectangular workpiece is positioned so that its front and rear edges are generally parallel to the front side of the brake.  
         [0007]     Such a position allows the typical brake to bend the workpiece along a line that is generally parallel to the workpiece&#39;s front and rear edges. It is common for the craftsman of a brake to position the workpiece manually, perhaps with the assistance of a helper, controlling the workpiece&#39;s orientation as it is presented to the brake. As the craftsman positions the workpiece upon the brake&#39;s clamping surface, he visually estimates, or perhaps determines with the assistance of temporary markings placed upon the workpiece, whether the workpiece is properly oriented or aligned relative to the brake.  
         [0008]     Considering that each workpiece is typically a several feet long, proper orientation and alignment operations take an inappropriately long time. Often, as the craftsman approaches one end of the workpiece, the opposite end of the latter may be accidentally moved out of alignment. Accordingly, it would be desirable to simplify these operations by providing, for example, stoppers operative to prevent the workpiece portion from accidental displacement.  
         [0009]     Typically, the workpiece must be cut from a coil of continuous sheet of material. This presents a problem as the coil is tightly wound for efficient shipping and storage. Once the retaining tape is removed the coil springs to unwind and is easily damaged or becomes soiled. To obviate this problem, craftsmen may work together—one craftsman unwinds the coil to the desired length of the individual workpiece and the other holds the still wound coil segment. However, this is highly inefficient use of manpower. Thus, it has been suggested that the coil be retained in some fashion while still being able to be unrolled.  
         [0010]     One suggestion is to use a cradling device that is positioned on its own legs adjacent to the bending brake. The material is then unrolled, cut and fed one at a time into the bending brake for bending. Problems are inherent with such an arrangement; for example while unwinding the coil, the cradling device may be knocked over; the coil may slip off the coil support and fall on the ground. Since the craftsman usually prepares numerous individual workpieces, recurrent resetting of the cradling device or mounting of the fallen coil considerably slows the craftsman and makes the entire process inefficient. Having the bending brake provided with a means for securing the coil can improve the efficiency of this machine.  
         [0011]     Furthermore after unwinding the coil at the desired length and using a cutter to sever the individual workpiece from the rest of the coil, the craftsman has a need to place the workpiece somewhere so as to proceed to cut the next workpiece or perform some other task. Typically, the workpieces end being aggregated on the ground where they are damaged or soiled. Thus, it would be desirable to have a table at the worksite so that the workpieces are stacked upon one another on that table. To accommodate this need, conscientious craftsmen attempt to fashion their own table. By necessity such a table must be long enough and wide enough for the cut workpieces. As a rule, such a table has a relatively cumbersome structure. Since equipment must be moved to new job sites, cumbersome tables are not desired. Therefore, it would be desirable to have the table that can be folded and/or easily transported and that would work efficiently to receive workpieces cut from the coil.  
         [0012]     Furthermore, at least some of the components of the known bending machines may not be ergonomically designed and tend to make the craftsman&#39;s job rather difficult. For example, some of the known brakes have rulers used by the craftsman to mark a portion of the individual workpieces that has to be bent. As mentioned before, each workpiece is typically a few feet long. Accordingly, while the craftsman marks different regions of the single workpiece for further uniform cutting or bending, he/she moves along the workpiece. The rulers, which typically extend transversely to the longitudinal axis of the machine, tend to interfere with the craftsman&#39;s movement. It would be desirable to mount the rulers to the machine in a manner allowing the craftsman to swing them to a position, in which the rulers would not hinder the craftsman&#39;s work.  
         [0013]     After the portion of the workpiece to be bent is uniformly marked, the craftsman clamps the workpiece between holding jaws and pivots them to an operative position, thereby bending the workpiece. Some of the known bending machines do not have a mechanism providing a positive lock between the holding jaws and workpiece. Others may be equipped with such a lock, but the structure of the lock may not be safe for the craftsman, who may have his/her fingers trapped in the lock, which can lead to devastating injuries. As a consequence, it is desirable to improve the known lock structures.  
         [0014]     Many of the known bending machines also have a slitter operative to cut the workpiece parallel to its longitudinal axis so as to provide the workpiece with the desirable width. Upon cutting, a cutoff portion simply falls on the ground. The craftsman and his assistants, typically, pick up the fallen piece from the floor and put it back on the table for further bending operations, if the width of the cutoff portion allows for such an operation. Clearly, the efficiency of the process is reduced, since picking the cutoff portion from the floor and putting it on the table take a relatively long time. It would be advantageous to provide the bending machine with a support, which is attached to the machine and configured to catch the cutoff piece before it falls on the floor.  
         [0015]     A need, therefore, exists for sheet bending brakes that operate in an efficient manner.  
         [0016]     Another need exists for sheet bending brakes that have an ergonomically configured structure.  
         [0017]     Another need exists for sheet bending brakes provided with a support that prevents falling cutoff pieces on the ground.  
         [0018]     Still a further need exists for sheet bending brakes that have an easily foldable and transportable structure.  
       SUMMARY OF THE INVENTION  
       [0019]     The present invention provides a number of improvements in sheet bending brakes directed to increase their efficiency. These improvements may be implemented separately from each other, or more preferably in combination with each other, as in the preferred embodiment of the invention herein disclosed.  
         [0020]     A bending brake, configured in accordance wit the invention, includes a main frame supporting a table that has two halves pivoting relative to one another between a working position, in which the halves are unfolded, and a folded position, in which one of the halves lies atop the other. The working position allows the craftsman to mount a coil of sheet material, repeatedly unwind the coil at the desirable length and cut individual sheet material strips, which further can be bent. The folded position drastically reduces the dimensions of the inventive bending brake, which can be easily transported or stored in a space-effective manner.  
         [0021]     While the bending brake has numerous applications, most frequently, it can be seen at a construction site. Typically, the craftsman and assistants displace the bending brake around the site as close as possible to the desired location so as to continue a construction process in a time-effective manner. To facilitate transportation of the bending brake around the site, the inventive bending brake is provided with two removably mounted legs and a pair of wheels, which are mounted on a bracket between the legs. If the craftsman desires to move the bending brake, the legs may be decoupled from the main frame, which, thus, remains supported only by the wheels and can be moved by a single person alone or by a small group of people on any turf including grass.  
         [0022]     After the bending brake has been positioned at the desired location, the craftsman couples a coil holder to the main frame. The coil holder, like many other details of the inventive brake, has a structure that allows the craftsman to work in a time-effective manner. For example, to prevent the coil of sheet material from falling on the ground, the holder has a pair of grippers reliably holding the coil until and unless the craftsman unlocks them. In accordance with a further aspect, the coil holder is provided with a built-in slitter assembly configured to sever an unwound strip of sheet material, which has the desired length.  
         [0023]     Having severed the desired number of sheet material strips, which are temporarily stored on the table, the craftsman may sequentially place the stored strips in the bending brake. In accordance with one aspect, the bending brake includes a mainframe assembly and has a plurality of spaced apart and uniformly configured frames. Provided with a plurality of rails and guides, the bending brake allows for placing and clamping of each sheet material strip in a precise cutting position. The built-in slicer is displaceable along the entire length of the mainframe and mounted thereon in a manner preventing its voluntary decoupling from the entire assembly.  
         [0024]     Numerous measuring features including pivotal and telescopic arms provided with measuring tapes are ergonomically designed to exclude any interference with the craftsman&#39;s work during the entire process. The telescopic arms functioning as a measuring unit for multiple bends of the same strip, are also used as a support table for the cut-off pieces of the clamped strip.  
         [0025]     These and other inventive features will be explained in detail in the following detailed description of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a front isometric view of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0027]      FIG. 2   a  is a side view of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0028]      FIG. 2   b  is a side view of a side view of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0029]      FIG. 2   c  is a side view of a side view of a sheet bending brake in accordance with one embodiment of the present invention wherein the sheet material has been bent.  
         [0030]      FIG. 2   d  is a detail view of a side view of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0031]      FIG. 3  is a rear isometric view of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0032]      FIG. 4  is an angled view of a coil holder in accordance with one embodiment of the present invention.  
         [0033]      FIG. 5  is a detail view of a portion of the table of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0034]      FIG. 6  is a detail view of a portion of a coil holder in accordance with one embodiment of the present invention.  
         [0035]      FIG. 7  is detail view of a portion of a coil holder in accordance with one embodiment of the present invention.  
         [0036]      FIG. 8  is an isometric view of a sheet bending brake in an operational condition in accordance with one embodiment of the present invention.  
         [0037]      FIG. 9  is a detailed view of a portion of a sheet bending brake in a further operational condition in accordance with one embodiment of the present invention.  
         [0038]      FIG. 10  is an isometric view of a sheet bending brake in a further operational condition in accordance with one embodiment of the present invention.  
         [0039]      FIG. 11  is a front view of a coil holder in accordance with one embodiment of the present invention.  
         [0040]      FIG. 12  is a detailed view of a portion of a coil holder in accordance with one embodiment of the present invention.  
         [0041]      FIG. 13  is a front view of a sheet bending brake receiving a sheet of material in accordance with one embodiment of the present invention.  
         [0042]      FIGS. 14A and 14B  are detailed views of portions of a sheet bending brake in accordance with one embodiment of the present invention.  
         [0043]      FIGS. 15A and 15B  are detailed views of portions of the sheet bending brake in accordance with one embodiment of the present invention.  
         [0044]      FIG. 16  is a detailed view of a portion of the sheet bending brake in accordance with one embodiment of the present invention.  
         [0045]      FIG. 17  is a sectional view of a sheet bending brake in operation in accordance with one embodiment of the present invention.  
         [0046]      FIG. 18  is a sectional view of a sheet bending brake in further operation in accordance with one embodiment of the present invention.  
         [0047]      FIG. 19  is an isometric view of a lock unit in accordance with one embodiment of the present invention.  
         [0048]      FIG. 20  is a detail view of a portion of a lock unit in accordance with one embodiment of the present invention.  
         [0049]      FIG. 21  is a detailed view of a portion of the sheet bending brake in accordance with one embodiment of the present invention.  
         [0050]      FIG. 22  is a detailed view of a portion of the sheet bending brake in accordance with one embodiment of the present invention.  
         [0051]      FIG. 23  is a detailed view of a portion of the sheet bending brake in accordance with one embodiment of the present invention.  
         [0052]      FIG. 24  is a detailed view of a portion of the sheet bending brake in accordance with one embodiment of the present invention.  
         [0053]      FIG. 25  is a detailed view of a portion of the sheet bending brake in accordance with one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0054]     Reference will now be made in detail to the entire assembly of the invention that is illustrated in the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. For purposes of convenience and clarity only, directional terms, such as top, bottom, left, right, up, down, over, above, below, beneath, rear, and front may be used with respect to the drawings. These and similar directional terms should not be construed to limit the scope of the invention in any manner. The words “connect,” “couple,” and similar terms with their inflectional morphemes do not necessarily denote direct and immediate connections, but also include connections through mediate elements or devices.  
         [0055]     The inventive bending brake assembly  10 , as shown in  FIG. 1 , is operative to provide a high output production of bent and hemmed strips of sheet material in a time-effective and craftsman-friendly manner. Constructed as a modular structure, bending assembly  10  includes several major components that are easily couplable with one another to form a relatively light and compact structure.  
         [0056]     A main frame  14  of assembly  10  includes a combination of rails and guides supporting a bending brake  18 , work table unit  22 , coil holder unit  20 , and bending/cutting unit  24 , each of which is discussed below in detail. Mounted on at least a pair of leg units  12 , assembly  10  is also provided with a wheel unit  26  for easy transportation.  
         [0057]     As a compact structure, the inventive bending brake assembly is delivered to a construction site in a folded position and characterized by foldable work table unit  22 , in which its rear half  28  is rotated so as to rest atop front half  30  ( FIG. 2   a ). Although leg units  12  are shown as attached to mainframe  14 , each of them can be dismounted from the frame by simply operating a respective one of leg handles  32  ( FIG. 2   a ) that are mounted on opposite sides of mainframe  14 . In addition, legs units  12  may be pivotally mounted to frame  14  and, instead of being completely detached from the frame, each leg unit may rotate to a rest position, in which it extends substantially parallel to the bottom of frame  14 .  
         [0058]     The table halves  28  and  30  each are configured with a respective frame  34  including a pair of longitudinal bars  36  and a plurality of crossbars  38 . Preferably, each longitudinal bar  36  has a rectangular cross-section, but this cross-section, of course, may be different. Two hinge assemblies  40  bridge inner sides of opposite ends of the table haves for providing an easy folding/unfolding operation of table unit  26 . Top surfaces of each half  28  and  30  are covered by a respective screen  42  preferably made of wire  44 . Front and rear top elongated bars  36  each have a respective extension  46  serving for receiving coil holder unit  20 , as will be explained below.  
         [0059]     Having selected the desirable location for bending brake assembly  10  at the construction site, the craftsman then rotates rear half  28  of the table unit away from front half  30  to the unfolded or working position of table unit  22 . To complete the conversion of brake assembly  10  from a storing position to a working one, the craftsman further mounts coil holder  20  to either of the opposite sides of table unit  22 , as shown in  FIG. 3 .  
         [0060]     Coil holder  20 , whose structure is illustrated in  FIG. 5  includes a pair of longitudinal L-shaped sides  50 , a plurality of cross members  52 , which bridge and couple L-shaped sides  50 , a plurality of rollers  54  for providing a smooth delivery of material onto work table unit  22 , and a cutting assembly  56 .  
         [0061]     To mount coil holder  20  to table unit  22 , the craftsman initially grabs the coil holder by inserting his hands through a pair of recesses  58  each formed approximately midway between the opposite ends of a respective one of L-shaped sides  50 . The inner end of each L-shaped side  50  has a mounting C-shaped bracket  60  provided with an attachment unit, which, in turn, includes a handle  62  fixed to a bolt. The craftsman holds the coil holder so that each bracket  60  receives a respective inner side of extension  46  ( FIGS. 4, 5 ,  6 ) of table unit  22  in such a manner that the bolts each extend into a respective threaded holes, which are formed on extension  46 . Upon rotating handles  62 , which are ergonomically structured to provide a reliable grip for the craftsman, he/she tightens the bolts and, thus, secures holder  20  to table unit  22 , as shown in  FIG. 6 .  
         [0062]     Thereafter, the craftsman loads the coil holder  20  with a coil of sheet material  64  ( FIG. 8 ) in the following manner. The craftsman pulls roller  70  off the coil holder, inserts it into coil  64  and further places opposite ends of roller  70  into U-shaped recesses  72 . To prevent displacement of roller  70 , the craftsman pivots spring-loaded levers  74  towards roller  70  so that recesses  76 , each of which is formed on a respective one of levers  74 , engage the opposite ends of roller  70  and lock this roller into place. Since levers  74  are biased towards the roller  70  by springs  78 , not only roller  70  is reliably secured to L-shaped longitudinal members  50  of coil holder  20 , but also coil  64  is biased towards and frictionally engages rollers  71  and  73  ( FIG. 7 ).  
         [0063]     After coil  64  is secured to coil holder  20 , the craftsman pulls the leading edge of the coil over an inner roller  68  ( FIG. 4 ). Finally, pivoting inner spring-loaded levers  66  ( FIG. 4 ), which support a roller  80 , so that the leading edge of coil  64  is sandwiched between rollers  80  and  68 , the loading operation of the coil is completed, as shown in  FIG. 8 .  
         [0064]     Sheet bending brake assembly  10  is now ready for a subsequent operation, during which the craftsman may prepare a plurality of strips of material each having the desired length, as will be discussed immediately below.  
         [0065]     Preparation of each individual strip of sheet material includes a measuring step, during which the craftsman applies a pulling force to the leading edge of material as shown in  FIG. 9  and unwinds the coil  64 , so that the individual strip having the desired length lies atop table unit  22 , as illustrated in  FIG. 10 , and a severing step. Since each of rollers  54  ( FIG. 4 ) has a respective plastic core, which is wrapped by a mesh screen, and sheet material is reliably engaged by the rollers, unwinding coil of material  64  requires an insignificant force and can be done in a time-effective and precise manner.  
         [0066]     To facilitate the precise measurement of the individual strips of sheet material, front and rear top edges of elongated sides  36  of table unit  22  each have a respective measuring tape  82  ( FIGS. 5 and 11 ) extending along the entire length of the table. The reason why both top edges of sides  36  have measuring tapes  82  is because coil holder  20  can be mounted on either end of table unit  22  and, depending on the direction in which the craftsman pulls an individual strip along the length of assembly  10 , he/she always can conveniently determine the desired length.  
         [0067]     Having completed the measuring step, the craftsman actuates cutting assembly  56 ,  FIGS. 11 and 12 , to sever the individual strip from the coil of sheet material. The cutting assembly  56  is configured with a C-shaped rail  84  ( FIG. 12 ) having an upwardly open guide channel, which is configured to guide a carriage  86  ( FIG. 8 ). The carriage  86  is relatively short by comparison with rail  84  and has two opposite flanges  88  each received within the guide channel of rail  84  so that the carriage can slide along the rail. Mounted to carriage  86  is a slicer  90  ( FIGS. 11 and 12 ) having a handle that can be gripped by the craftsman who applies a force to the handle so as to displace the carriage and slicer along rails  84  in a plane extending perpendicular to the opposite elongated edges of the individual strip of sheet material. Having severed one individual strip, the craftsman may continue to sever as many strips as needed.  
         [0068]     As further shown in  FIGS. 11 and 12 , slicer  90  has an S-shaped housing  92  provided with a substantially horizontal outer channel  94 , which faces roller  80  of holder assembly  20  and is configured to confine a new leading edge of coil  64  after severing the previous individual strip. Housing  92  is also provided with a slanted inner channel  96  ( FIGS. 6 and 12 ), which is configured to deflect the inner end of the individual strip downwards as the cutting assembly  56  advances across the strip.  
         [0069]     Two rollers  98  and  100  perform a cutting operation, each cutter having opposing edges overlapping one another in a vertical plane for severing the strip from coil  64 .  
         [0070]     After severing each individual strip from coil  64  of sheet material, the craftsman can continue with cutting the strip into multiple elongated pieces, since usually the width of individual strips is substantially greater than needed. Referring to  FIG. 13 , bending/cutting unit  24  constitutes a component of mainframe  14  and is configured to cut individual strips and further bend cut pieces of the strip, as will be explained below.  
         [0071]     During the initial stage of the cutting and bending operation, the craftsman pivots a handle  102  ( FIG. 13 ) towards worktable unit  22 . Displacement of handle  102 , which is removably mounted to a midsection of mainframe  14 , causes an upper jaw  104  of the bending assembly to move away from a lower jaw  106  so as to form a passage  108  opening into a C-shaped frame  110 . As the strip is guided through passage  108 , the craftsman orients it so that only the strip&#39;s outer end portion  112  protrudes outwards from jaws  104  and  106 , while the rest of the strip lies inside C-shaped frame  110 . After aligning outer end portion  112  of the strip, which protrudes from the jaws at the desired distance, the craftsman clamps and subsequently positively locks the strip between the jaws and performs a cutting operation.  
         [0072]     Aligning the individual strip or, in other words, providing strip&#39;s outer end portion  112  with the desired width may be realized in accordance with different embodiments. In one embodiment, a measuring/aligning assembly  114 , as shown in  FIGS. 14A-14B ,  15 A- 15 B has at least two units spaced from one another and each including a U-shaped housing  116 , which extends under table unit  22  between a rear rail  120  and a front rail  122  of mainframe  14  ( FIGS. 13 and 14 A). Opposite ends of housing  116  are provided with mounts  118 ,  124  ( FIGS. 14A and 14B ), respectively, each of which is configured to receive a respective one of front and rear rails  122  and  120 , respectively. Rear mount  124  has a pair of clamps  126  operative to lock the entire unit in the mounting position thereof, in which not a single part or portion of the measuring units extends beyond opposite front and rear rails  122  and  120 , respectively, of mainframe  14 .  
         [0073]     To provide proper measurement or alignment of strips, each unit of assembly  114  has a slideable support arm  128  ( FIG. 14B ) configured as a U-shaped bracket, which is dimensioned to slide inside U-shaped housing  116 . Thus, housing  116  and slideable support arm  128  forms a telescopic arm operative to extend beyond front rail  122  of mainframe  14  at the desired distance. To set the desired width, the craftsman reaches for slideable support arm  128  and pulls it out. The top of slideable support arm  128  has two rulers, one for bending  132  and one for cutting  130  ( FIG. 14B ), and is further provided with a handle  134 . Having two different rulers is necessary because the bending and cutting assemblies operate in different planes. The handle  134  is pivotally mounted to slideable support arm  128  and swivels between a rest position, in which it extends within a recess  136  so as not to interfere with the slider&#39;s displacement, and an erected position, in which handle  134  extends upwards.  
         [0074]     After the craftsman adjusts the outer edge of the strip to be cut or bent in accordance with the desired width, he initially pivots handle  102  ( FIG. 13 ) to a clamping position, in which upper and lower jaws  104  and  106 , respectively, slightly press upon the opposite sides of the strip. Then, the craftsman displaces slideable support arm  128  so as to have erected handle  134  next to the strip&#39;s edge, as shown, for example, in  FIG. 15B  and locks the strip, thereby preventing its further displacement by tightening assembly  138  ( FIGS. 14A and 14B ) that extends through elongated parallel slits  140  ( FIG. 14B ), which are formed in both housing  116  and slideable support arm  128 . Assembly  138  includes a bolt extending through slits  140  and having on its top end a head  142  and on the lower end a handle (not shown), which is screwed onto this lower end. The craftsman rotates the handle so as to adjust the pressure of head  142  against the slider&#39;s top and, thus, locks displacement of housing  116  and slideable support arm  128  relative to one another in the desired position. This locked position is particularly advantageous for multiple repeat bents.  
         [0075]     In accordance with a further embodiment, the measurement operation can be realized by an assembly, which includes a support  144  ( FIGS. 15A, 15B  and  16 ), pivotally mounted on and coextending with the upper jaw  104  of bending brake  18 , and one or several rulers  146  coupled to support  144 . Rulers  146  pivot along with support  144 , and each of the rulers may slide along the support and swivel to a respective rest position, in which the rulers extend parallel to support  144 . In addition, rulers  146  each are provided with two measuring scales  148  and  150  used for setting the bending and slicing width, respectively.  
         [0076]     The measuring assemblies disclosed above can be used separately or in combination with one another. For example, after inserting the individual strip of sheet material in passage  108  ( FIG. 13 ) and displacing handle  102  to the clamping position ( FIG. 15B ), the craftsman may pivot support  144  with rulers  146  downwards from a position shown in  FIG. 15A  to a position of  FIG. 15B  and make necessary measurements on the inserted strip. Thereafter, extending slideable support arm  128  of assembly  114  ( FIG. 14B ) at the desired distance and displacing handle  134  of slideable support arm  128  to its erected position, the craftsman may make numerous slices and/or bents without further using rulers  146  . Assembly  114  is particularly advantageous for ultra accurate repeat bents; excellent for wrapping posts, 4×4&#39;s etc. Once, the craftsman does not need to use rulers  146  anymore, he/she pivots the support  144  upwards away from upper jaw  104  ( FIG. 16 ) and, then, swivels rulers  146  to the rest position, in which they do not interfere with the craftsman&#39;s work.  
         [0077]     After the desired width of a piece to be cut is established, the craftsman moves handle  102  to its locked position, in which the strip is prevented from displacement relative to upper and lower jaws  104  and  106 , and begins a slicing operation . A cutting unit  152  including a slicer  154 , which can be configured identically to slicer  90  shown in  FIGS. 11 and 12 .  
         [0078]     A mounting assembly of slicer  154 , better illustrated in  FIGS. 15A and 15B , includes a rail  156  slidably inserted into a C-shaped channel  158  of lower jaw  106 , so as to slide along channel  158  along the entire length of the locked strip. Since the length of jaws  104  and  106  is greater than the length of the strip of sheet material, the craftsman is able to position the slider outside the ends of the strip, so it would not interfere with the craftsman&#39;s work during measuring and bending operations.  
         [0079]     The slicer is so mounted that it cannot accidentally slide off the rail  107  associated with the lower jaw  106 , since the mounting assembly of the slicer is provided with a stop unit. The stop unit includes an elongated metal body  158 , which has an inner end slidably inserted into a channel  160  of the rail  107  associated with the lower jaw  106 , and an outer end provided with a holder  162  that supports a spring-loaded body  164  having a handle  166 . In a blocking position, spring-loaded body  164  extends towards lower jaw  106  and arrests displacement of slicer  154 , thereby preventing the latter from falling off the jaw. If the craftsman needs to dismount the slicer, he/she will pull handle  166  away from the slicer and simply slides the latter until it goes off rail  107 . Since the slicer is mounted to rail  107 , it rotates with this rail during a bending operation. Note that body  158  is configured to slide within channel  160  of rail  107  and can be retracted into this channel in the storing position of the assembly  10  so as to minimize the overall the size of the latter.  
         [0080]     After one or a numerous number cutoff pieces are produced and stored on table unit  22 , the craftsman can begin the bending operation. Similarly to the cutting operation, each piece is inserted into C-shaped frame  110 , measured to have the desired width and finally locked upon bringing handle  102  in a locking, upright position.  
         [0081]     Turning to  FIGS. 17-20 , showing a section  17 - 17  of  FIG. 1  of the bending brake according to one embodiment of the present invention, the bending assembly includes a bending brake  18  each including an upper arm  170  and a lower arm  172 , which supports rail  107  pivotably through a rotation hinge  107   b  which contacts a striking surface  107   a  to an anvil  104   a  on upper jaw  104  to the sheet material ( FIGS. 2   b  and  2   c ).  
         [0082]     Formed as a one-unit piece, each pair of upper and lower arms  170  and  172  , respectively, defines C-shaped frame  110  that has its rear end attached to rear rail  120 , whereas upper arms  170  of bending brake  18  are interconnected with one another by a top circular pipe  174  along a pivot  174   a . Pipe  174  is associated with a roller  175  that rolls on a cam surface  206  having a rest position  206   a  ( FIGS. 2   a  and  2   d ). Pivotally attached to each upper arm  170  is a lever  176 , which has two spaced apart and interconnected parts  171  that are fixed to upper jaw  104  and move between an open position of jaws  104  and  106 , a clamping position of jaws and a locked position of jaws. Displacement of the upper arm is caused by a force applied by the craftsman to one or more U-shaped handles  102 , which are detachably coupled to top pipe  174 , during measuring, cutting and bending operations.  
         [0083]     To lock jaws  104  and  106 , the craftsman again applies a pulling force to handle  102 , which is translated into pivoting of lever  176  through rotation of top pipe  174  and a lock unit  178 , which, in turn, has a flange  186  ( FIG. 18 ) attached to lever  176  between its parts  171 . As can be seen in  FIG. 24 , although inner surface  182  of lock unit&#39;s body  204  is curved, it does not extend complementary to top pipe  174  and, thus, serves as a cam that is operative to positively lock the lever  176 , when handle  102  extends perpendicular to the clamped strip or piece of material during the slicing and bending operations, respectively. While the craftsman pivots handle  202  along with pipe  174  from the open position of jaws  104  and  106 , the pipe  174  pivots and presses roller  175  against and pushes inner surface  182  of the lock unit downwards, which causes lever  176  and upper jaw  104  to follow the lock unit&#39;s displacement. At the end of this displacement, the upper jaw approaches and slightly presses against lower jaw  106 , thereby bringing the jaws in the clamping position ( FIG. 17 ).  
         [0084]     However, in the clamping position, the strip of sheet material engaged between the jaws still can move. To positively lock the clamped strip, the craftsman applies an additional force and brings pipe  174  in positive engagement with the lower portion of inner surface  182 , namely cam surface  206 , of the lock unit, which corresponds to the locking position of the jaws, namely locking position  206   a.    
         [0085]     During displacement of lock unit  178  relative to pipe  174 , the opposing surfaces of these components approach each other and may come in contact, which can either prevent further displacement of the components or, if the craftsman will apply an excessive force, damage them. To avoid such a possibility, body  204  of lock unit  178  is provided with a roller  192  ( FIG. 19 ) guided against pipe  174  only when the jaws move between the open and clamping positions associated with minimal stresses upon the displaceable components. In the locking position, which is associated with very significant forces, roller  192 , due to the geometry of inner surface  182  of body  204 , is spaced at a distance from pipe  174 , thereby effectively operating for a long period of time.  
         [0086]     Furthermore, the interlocking unit  178  includes body  204  having inner portion  206 . Inner portion  206  includes a cam surface that as shown in  FIG. 19  includes a depressed portion, a rising hill portion, and a depressed locking position  206   a.    
         [0087]     Also, in the locking position of the jaws, inner portion  206  of lock unit&#39;s body  204  is compressed between pipe  174  and lever  176 . It is not unusual that the craftsman may apply an unnecessary excessive force to handle  102  in the locking position of the jaws just to make sure that this position has been indeed established. To ensure that lock unit  178  is not damaged as a result of the additional forces and provide reliable engagement between a base  196  and inner portion  206  of the lock unit, a washer  210  is inserted between the opposing surfaces of these components and coupled to them by a bolt  212  extending through openings  214  ( FIG. 20 ) of these parts, which are aligned upon mounting the lock unit to lever  176 .  
         [0088]     Eventually, due a heavy use of assembly  10 , washer  210  may deform. As a consequence, attachment between lock unit  186  and lever  176  may become less reliable, which, in turn, can lead to the inefficient operation of assembly  10 . To compensate deformations of washer  210 , bolt  212  has an additional washer  216 , which is substantially thinner than washer  210 . Accordingly, if the craftsman feels that the engagement between the jaws is not positive, he may unscrew bolt  212 , and place washer  216  next to washer  210 , reestablishing, thus, the desired form and size of the latter. This operation is very simple and does not require disassembling of entire lock unit  178 .  
         [0089]     As also shown in  FIGS. 19 and 20 , lock unit  178  has a frame including two spaced apart, curved guards  188 , which are configured so as to prevent any injury to the craftsman during locking and unlocking of upper and lower jaws  104  and  106 , respectively. Guards  188  are mounted on and pivot about lower pin  203 , which extends through a passage formed in the lower portion of body  204 , whereas the upper stretches of these guards are mounted on a second pin  207 , which moves along recesses  198  during displacement of the lock unit. When the craftsman rotates handle  102 , the inner surface of guards  188  are always in a close proximity of pipe  176  because of their shape and because the guards are biased towards the pipe by a resilient element  190 , which is mounted on the opposite ends of pin  203 . As a consequence, the fingers of the craftsman cannot be squeezed between the lock unit and the pipe.  
         [0090]     Upon bringing jaws  104  and  106  in the locking position, the craftsman reaches for one or more handles  184  ( FIGS. 18, 21  and  22 ) and pulls them upwards so as to produce a bend. In a rest position, when the craftsman does not need these handles, they may swivel from a downright position ( FIG. 21 ) to a horizontal position ( FIG. 22 ), in which a U-shaped holder  183  ( FIG. 21 ), mounted to mainframe  14 , engages the handle.  
         [0091]     As is often happens at the construction site, the craftsman may need to move assembly between different locations. To provide easy transportation of the assembly, mainframe  14  can removably support wheel unit  26 , as illustrated in  FIGS. 23-25 . Wheel unit  26  is configured with a frame  220 , wheels  222  and handle  224 . Frame  220  is shaped and dimensioned to extend under mainframe  14  and has its opposite ends removably attached to front and rear rails  122  and  120 , respectively, of the frame. Handle  224  is spring-loaded so that it is biases towards and engages front rail  122 . Accordingly, when the craftsman applies a pulling force to the handle, it can be disengaged from the front rail. As can be seen in  FIG. 1 , in the mounted position, wheel unit  26  does not reach for the ground, since leg units  12  are longer than wheel assembly  26 . However, dismounting either one of the leg units or both, allows the craftsman to utilize wheels  222  that are configured similar to wheels of a lawnmower. Frame  220  is so attached to front and rear rails  122  and  120 , respectively, that it can slide therealong so as to allow the craftsman to selectively position wheel unit  26  under mainframe  14 .  
         [0092]     This document describes the inventive assembly for illustration purposes only. Neither the specific embodiments of the invention as a whole, nor images, nor those of its features limit the general principles underlying the invention. The specific features described herein may be used in some embodiments, but not in others, without departure from the spirit and scope of the invention as set forth. Many additional modifications are intended in the foregoing disclosure, and it will be appreciated by those of ordinary skill in the art that in some instances some features of the invention will be employed in the absence of a corresponding use of other features. The illustrative examples therefore do not define the metes and bounds of the invention and the legal protection afforded the invention.