Patent Publication Number: US-6988323-B2

Title: Tool kit and method for working sheet metal trims

Description:
FIELD OF THE INVENTION 
   This invention pertains to gauges and instructions for bending sheet metal, and more particularly it pertains to angle gauges and corresponding trigonometric tables to facilitate the fabrication of sheet metal building trims. 
   BACKGROUND OF THE INVENTION 
   When installing aluminum or vinyl siding on a building, aluminum caps are also installed over the window frames and the eaves of the building. In many cases, cornices and friezes are also installed above the windows and doors to further decorate the building. While some decorative mouldings can be purchased prefab, most installers prefer to form the aluminum covers onsite using a portable sheet metal bender. However, the bending of sheet metal represents a challenge, especially to the novice or the apprentice in the trade and sometimes large amount of material and time can be wasted before quality work is obtained. 
   The known sheet metal benders are sold without stopper to limit the movement of their aprons to a specific angle. The frequent users of sheet metal benders eventually develop a skill for judging the working of the apron to obtain the desired angle, taking into consideration the material thickness and the amount of spring back. However, even the experienced tradesmen must remove the workpiece from the bender once or twice, measure the angle at several places along the bend, and put the workpiece back into the bender to readjust the angle of the bend. 
   It is believed that the prior art is generally short of suggestion with regards to controlling the movement of the apron of a sheet metal bender to obtain the desired bend at the first time. As such, it may be appreciated that there continues to be a need for a tool kit that may be used by aluminum siding installers to facilitate their work. 
   SUMMARY OF THE INVENTION 
   In the present invention, there is provided a set of angle gauges that are laid on the workpiece while the workpiece is being bent in the bender, to measure at a glance the angle being formed and to obviate the need for removing the workpiece from the bender several times before obtaining the required bend. 
   In one aspect of the present invention, there is provided an angle gauge having an elongated shape with juxtaposed longitudinal base surface and longitudinal angled surface, and an indicia applied thereon indicating a nominal angle. The angled surface makes a true angle with a transverse projection of base surface. The true angle is larger than the nominal angle to accommodate for the thickness of the nose bar in the sheet metal bender. When using a portable common sheet metal bender having a nose bar tapering along a 20° slope, the true angle corresponds to the sum of the nominal angle shown on the indicia and a supplement angle of 20°. 
   In use, the angle gauge is laid on the nose bar of the bender and on the workpiece as the workpiece is being formed, to monitor the formation of the workpiece to the desired nominal angle. 
   In another aspect of the present invention, there is provided a set of angle gauges for measuring angles in a workpiece being formed in a sheet metal bender. As previously described, each of the angle gauges in the set has an elongated shape, an indicia indicating a nominal angle, a base surface and an angled surface making a true angle with a projection of the base surface. This true angle corresponds to the sum of the nominal angle plus a supplement angle. The nominal angles on the angle gauges in the set are different from each other, and the supplement angle is common to all the angle gauges in the set. The entire set can thereby be used on a same sheet metal bender to measure different angles. 
   In yet another aspect of the present invention the set of angle gauges is part of a tool kit which also comprises printed math tips and charts related to the use of the angle gauges. The math tips and charts are expressed in fractions of an inch. This tool kit is advantageous for use on a job site by tradesmen having no calculator nor trigonometric table and wherein their measuring instruments are limited to a square and a measuring tape. 
   In a further aspect of the present invention, there is provided a method for bending a workpiece to a nominal angle in a sheet metal bender. This method comprises the first step of providing an angle gauge as previously described. Subsequent steps consist of setting and clamping the workpiece in the sheet metal bender and forming an obtuse angle in the workpiece. The angle gauge is laid in the obtuse angle and over the nose bar, and the bending of the workpiece is carried out until the workpiece is in contact with the angled surface of the angle gauge. 
   The apron bar can be released lightly to verify the spring back in the material. When over-bending to compensate for spring back in the workpiece, the angle gauge floats upward to accommodate for the additional displacement of the apron bar, and moves back to the bottom of the bend as soon as the apron bar is tilted back down. 
   Once the workpiece is in full contact with the angled surface of the angle gauge without any pressure thereon from the apron bar, the bent obtained in the workpiece corresponds to the nominal angle shown on the indicia of the specific angle gauge used. 
   The angle gauge is free to slide from one end of the workpiece to the other to quickly verify a desired angle. The measured angle can be gauged at a glance from the position normally held by a person operating the bender. 
   This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the present invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 
       FIG. 1  is a perspective end view of three pairs of floating angle gauges according to the preferred embodiment of the present invention, and printed cards showing corresponding math tips and charts; 
       FIGS. 2 ,  3  and  4  illustrate respectively the end view of a 30°, 45° and 90° floating angle gauges according to the preferred embodiment of the present invention; 
       FIGS. 5 and 6  illustrate respectively a perspective view and an end view of a common portable sheet metal bender used by aluminum siding installers; 
       FIG. 7  shows an enlarged end view of the apron bar, anvil bar and pinch bar of the sheet metal bender illustrated in  FIGS. 5 and 6 ; 
       FIG. 8  illustrates an example of a window and of a flower box capped with sheet aluminum and decorated with matching frieze and moulding made with the tool kit according to the present invention; 
       FIGS. 9 and 10  illustrate cross-sections of friezes and cornices made using the tool kit according to the present invention; 
       FIGS. 11 and 12  illustrate two examples of printed cards showing math tips and charts included in the tool kit according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will be described in details herein a specific embodiment, with the understanding that the present disclosure is to be considered as an example of the principles of the invention and is not intended to limit the invention to the embodiment illustrated and described. 
   Referring to  FIG. 1 , the tool kit  20  according to the preferred embodiment of the present invention contains several floating angle gauges  22 ,  24 , and  26 , for measuring common angles, and math tips and charts  28  that are printed on card stock for example or in a booklet form. For convenience, these charts are illustrated and described as stiff cards having a size suitable for carrying in a shirt pocket. 
   The preferred floating angle gauges  22 ,  24 ,  26  are made of bent or extruded metal strips or bars and have a length of about 10–14 inches. Each of these metal strips or bars has an angled surface  30 ,  32  or  34  of which the true angle from a projection of the base surface  36  corresponds to the nominal angle to be formed therewith plus a supplement angle. The angled surface  30  of the 30° angle gauge  22  forms a true angle of 50° from a transverse projection of the base surface  36  thereof, as illustrated in  FIG. 2 . The 45° angle gauge  24  has an angled surface  32  angled at 65°, and the 90° angle gauge  26  has an angled surface  34  angled at 110°. In the illustrated examples of  FIGS. 2–4 , the supplement angle in all three angle gauges is 20°. The nominal angle of each angle gauge is shown on an indicia engraved on or otherwise affixed to each angle gauge, as illustrated in  FIG. 1 . The amplitude of the supplement angle will be explained below. 
   Referring now to  FIGS. 5–7 , the common sheet metal bender  40  has an anvil bar  42 , a nose bar  44  articulated up and down by cams and a lever  46 , and an apron bar  48  articulated angularly about a pivot axis  50  by a pair of handles  52 . In a common portable bender, the top surface of the nose bar  44  tapers down and forms and angle of about 20°, as illustrated in  FIG. 7 , with the clamping surface of the anvil bar  42 . This angle becomes the supplement angle in the angle gauges  22 ,  24 ,  26 . 
   The sheet metal bender illustrated in  FIGS. 5–7  is referred to in the industry as a Port-O-Bender™, available from Tapco™ International Corporation, having distributors around the world. The nose bar  44  on these benders has a slope divergence  54  on its upper surface at a distance of about 1⅛ inches from its outer edge  56 . Therefore the preferred width ‘A’ of the base surface  36  of each angle gauge  22 ,  24  or  26  is 1⅛ inches or slightly less. 
   Along the same lines, the preferred width ‘B’ of the angled surface  30 ,  32  and  34  is about ½ inch, such that each angle gauge is usable to measure tight bends on a workpiece. 
   In use, one of the angle gauges  22 ,  24  or  26  is laid against the nose bar  44  and the workpiece  58  being bent. The angle measured is the inside angle of the workpiece  58  as the apron bar  48  is being tilted upward. Therefore, the angle gauge having a 50° angled surface is used to measure an inside angle of 30°. Similarly the other angle gauges are used to measure inside angles corresponding to the angled surface on the respective bar less the angle of the nose bar of the particular bender. 
   To form a bend, the workpiece  58  is set and clamped in the bender  40  and a slight obtuse angle is formed therein as illustrated in  FIG. 7 . Then one or a pair of angle gauges  22 ,  24  or  26  is laid against the top surface of the nose bar  44  and in this obtuse angle. The workpiece  58  is then bent by working the apron bar  48  until the bent portion of the workpiece  58  touches along the angled surface of the angle gauge  22 ,  24 , or  26 . The spring back in the material is verified by releasing the apron bar lightly. If over-bending is required, the angle gauge moves upward across the nose bar according to the movement of the apron bar, and slides back to a measuring position when the apron bar is released. The workpiece  58  is then removed from the bender with the proper bent formed therein. 
   The angle gauges  22 ,  24 ,  26  are not fixed to the bender or to the workpiece. The angle gauges are loosely laid onto the workpiece after setting a small obtuse angle in the workpiece. The angle gauge can be slid from one end of the bender to the other or used in pair, one on each end of the bender, to quickly measure an angle along the entire length of a workpiece  58 . These angle gauges are also convenient for verifying the accuracy of a new bender to quickly identify a twisted apron bar  48  for example. 
   Referring now to  FIGS. 8–10  there are illustrated therein a window header  60  manufactured using the tool kit according to the present invention and a covered flower box  62  having the same style as the window header  60 . There are also illustrated the cross-sections of two different types of headers or cornices  64 ,  66  showing typical locations of 45° angles found on these mouldings. 
     FIGS. 11 and 12  illustrates math tips and charts printed on stiff cards. The preferred card stock is a stiff plastic material or a cardboard laminated with a plastic cover. These cards  70 ,  72  have dimensions to fit into a common shirt pocket, such that they can be carried along and stowed away by tradesmen during normal working activities. These printed math tips and charts may include for example, trigonometric tables associated with the bending of sheet metal in caps for bay window frames, planar window frames, mouldings, friezes and cornices. 
   For example, the card  70  illustrated in  FIG. 11  shows the sine and cosine dimensions of a 45° angle and of a 30° angle. These charts are used to calculate the projection at right angle from a wall of a section extending at 30° or 45° from that wall. These charts are also used to calculate the total height and depth of a moulding having one or more segments extending at 30° or 45° from a mounting surface, such as those illustrated in  FIGS. 9 and 10 . 
   Also for example, the card  72  shown in  FIG. 12  has instructions to calculate the projections at right angle from a base line on a workpiece used for capping the frame of a bay window. For example, a ⅞″ right angle projection  74  from a base line  76  of a piece extending at 45° from a wall surface  78  corresponds to a distance of 1¼″ along the wall (⅞″×secant 45°) and to a ⅜″ linear projection  80  (⅞″×tangent 22½°) at the 22½° corner. 
   Although only two math tip and chart cards  70 ,  72  have been illustrated, it will be appreciated that a number of additional printed instruction sheets  28  may be included in the tool kit according to the preferred embodiment. For example, there may be included an entire booklet showing tips and related trigonometry for making mantles, faceted columns, window sills, window headers, caps for channelled vinyl windows, cornices and friezes for restoring heritage buildings, etc. 
   It will be readily appreciated that the floating angle gauges  22 ,  24  and  26  for another type of bender may have a different width or a different supplement angle to accommodate the shape of the nose bar of that other bender. It will also be appreciated that the tool kit may contain other gauges having other nominal angles than those illustrated. 
   Although the tool kit according to the present invention is described and illustrated as a combination of floating angle gauges and printed math tips and charts, it will be appreciated that the floating angle gauges can be used alone without the math charts to obtain a new and useful result. Therefore, it should be appreciated that the essence of the present invention consists of the angle gauges with or without the printed math tips and charts. 
   As to other manner of usage and operation of the present invention, the same should be apparent from the above description and accompanying drawings, and accordingly further discussion relative to the manner of usage and operation of the invention would be considered repetitious and is not provided. 
   While one embodiment of the present invention has been illustrated and described herein above, it will be appreciated by those skilled in the art that various modifications, alternate constructions and equivalents may be employed without departing from the true spirit and scope of the invention. For example the angle gauges  22 ,  24  and  26  may also be made of extruded plastic material, or wood. Therefore, the above description and the illustrations should not be construed as limiting the scope of the invention which is defined by the appended claims.