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BACKGROUND OF THE INVENTION 
     There have been various designs for metal roofing shingles. These metal shingles typically attempt to replicate the aesthetic properties of traditional slate and cedar shingles while maintaining a degree of weather resistance expected with steep slope roofing products. Numerous patents have been granted on variations of these shingles, all of which attempt to create a substantially weather resistant metal shingle. Examples of these shingles can be found in U.S. Pat. No. 503,173 (Spahmer), U.S. Pat. No. 1,597,993 (Meurer), U.S. Pat. No. 1,743,206 (Fulenwider et al), U.S. Pat. No. 1,876,597 (Bennett), U.S. Pat. No. 5,469,680 (Hunt), and U.S. Pat. No. 5,832,686 (Plath et al). 
     The Spahmer patent discloses a single course shingle system where the opposing sides of each shingle are bent to create interlocking folds. Similarly, the top and bottom edge of each shingle are optionally bent to create interlocking folds. These shingles can then be assembled together by inserting the left edge of the shingle into the right edge of a previously installed shingle, while inserting the bottom edge into the top edge of a second previously installed shingle. The Spahmer patent discloses cutting the metal away in each of the corners to facilitate the process of creating folds along each edge. As a result, the corners of the shingles are susceptible to leakage in the event of severe weather conditions. 
     The Meurer patent discloses a single course shingle system where the left side of each shingle contains a tongue and the right side of each shingle contains a corresponding groove. Also present on the right side is a nailing strip designed so as to facilitate the installation process. In this patent, upper rows of shingles overlap the adjacent lower row, however, there is no interlocking mechanism between these two rows. As a result, the shingle is susceptible to leakage during severe weather conditions when water may be blown upwardly between the rows. 
     The Fulenwider patent discloses a single course shingle system where each shingle has opposing side edges that define corresponding shoulders, an underturned bottom edge and an overturned top edge. The overturned top edge is secured to a separately formed lock fastener. The slightly upturned lip of the lock fastener engages with the underturned bottom edge of the shingle directly above it. However, the lock fastener does not create an adequate seal and therefore the shingle is susceptible to leakage during severe weather conditions. 
     The Bennett patent discloses a single course shingle system where each shingle has opposing overturned and underturned side edges and an underturned bottom edge. A dam strip is used to secure the top edge of the shingle to the roof. Nail holes are provided in the flat surface of the shingle, where they are overlapped by the adjacent upper row of shingles. This system is susceptible to leakage through the nail holes and along the dam strip during server weather conditions, when water may be blown upwardly between the rows. 
     The Hunt patent discloses a single course shingle system where each shingle has an overturned top edge and a corresponding underturned bottom edge, which is used to interlock adjacent rows of shingles. A joint pan is placed under adjacent shingles. This joint pan guides any water that leaks through onto the lower row of shingles. However, this system is still susceptible to leakage when water is blown upwardly on the joint pan. 
     The Plath patent discloses a single course shingle system in which a gutter is formed in the trailing edge by creating an “s” shaped fold. The opposing edge is not folded and is inserted into the “s” shaped fold as the shingles are installed. The top edge is overturned, and the bottom edge has a corresponding underturn. The underturn at the bottom edge of each row of shingles interconnects with the overturn at the top edge of the lower row of shingles. The gutter helps guide water from between adjacent shingles down onto the outer surface of the lower row. However, the upper edge of the gutter is not folded, so leakage can occur if water is blown upwardly through the gutter during severe weather conditions. 
     Because of the inherent stiffness and formability of metal, creating a water-resistant metal shingle system that does not leak is a difficult undertaking. The installation of such a roofing system is also difficult. Each of the aforementioned patents attempts to solve some aspect of these shortcomings. 
     SUMMARY OF THE INVENTION 
     The problems of the prior art have been overcome by the present invention, which provides a metal shingle system which is resistant to leakage, even under severe weather conditions. The key attribute of the new system occurs at the intersection point between the top edge and the side edge of the shingle. This design innovation ensures that moisture (or water) cannot flow upward and seep under the shingle course above. Briefly, the top edge is overturned and the bottom edge is underturned such that each row of shingles can be horizontally interconnected. In addition, one side edge is folded to form a gutter area into which water that seeps between laterally adjacent shingles is collected and drained onto the lower row of shingles. By overturning the top edge, as well as the top of the gutter area, this moisture block is extended into the gutter region and ensures that moisture is collected and drained onto the lower row of shingles. Also disclosed is a useful tool for forming the cut edge of the shingles, such as is needed at the end of the roofline and around roof penetrations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a shingle in accordance with a first embodiment of the present invention; 
         FIG. 2  is a top view of a shingle in accordance with a second embodiment of the present invention; 
         FIG. 3  is a cross sectional view of the shingle in  FIG. 1  taken along line A-A; 
         FIG. 4  is a cross sectional view of the shingle in  FIG. 1  taken along line B-B; 
         FIG. 5  is a perspective cross sectional view of a mounting tab of the shingle in  FIG. 1 ; 
         FIG. 6  is a perspective cross sectional view showing the interconnection of two shingles in adjacent rows; 
         FIG. 7  is a side view showing the interconnection of two shingles at the mounting tab; 
         FIG. 8  is an exploded view of the upper right edge of the shingle in  FIG. 1 ; 
         FIG. 9  is an exploded view of the lower right edge of the shingle in  FIG. 1 ; 
         FIG. 10  is a side view showing the interconnection of two adjacent shingles in the same row; 
         FIG. 11  is a perspective view of a first embodiment of the pliers used in the present invention to bend the shingle of  FIG. 1 ; 
         FIG. 12  is a perspective view of a second embodiment of the pliers used in the present invention to bend the shingle of  FIG. 1 ; and 
         FIG. 13  is a perspective view of a shingle bent using the pliers of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a top view of a first embodiment of the metal shingle of the present invention. Metal shingle  10  is designed such that preferably about 8.625 inches of each metal shingle, as measured from top to bottom is exposed, and is preferably about 40.75 inches wide, although other sizes and ratios are acceptable. The preferred height and width of the exposed area are selected to simulate the appearance of traditional shingles. It provides installers with a metal shingle that is dimensionally similar to that which they use today. The width of the shingle can vary, if desired. Greater widths allow faster installation, since there are fewer shingles to install. Greater widths also allow higher metal utilization. However, greater shingle widths can be awkward to work with, especially in cases where there are gables and other irregularities in the roofing surface. 
     Shingle  10  has a top surface  15 , which may be unfinished as in the case of copper, or preferably painted or otherwise decorated so as to resemble a cedar shingle. In the preferred embodiment, the top surface has a plurality of indentations  40  oriented longitudinally from the top edge  20  to the bottom edge  30  so as to give the appearance of multiple individual shingles, each roughly 4 to 8 inches in width, although these dimension can vary. 
       FIG. 2  shows a second embodiment of metal shingle  10 . In this embodiment, the dimensions are the same as those in  FIG. 1 . However, the longitudinal indentations are spaced at different intervals than those of the first embodiment. In the preferred implementation, roofing installations would employ a combination of these embodiments so as to provide a random appearance when installed. While two specific embodiments are shown here, many others are possible, and the invention is not limited to solely these two embodiments. Additionally, more than two different embodiments can be employed to provide a more random appearance, if desired. 
       FIG. 3  shows a cross-sectional view of metal shingle  10 . Top edge  11  is folded over top surface  15  so as to form a first C shape  21 . Bottom edge  12  is folded under top surface  15  so as to form a second C shape  22 . During installation, the C shape  22  created by the bottom edge  12  of one shingle is engaged with the C shape  21  created by the top edge  11  of the shingle on the next lower row, which was previously installed. This interconnection method is well known to those skilled in the art.  FIG. 6  illustrates this interconnection, with the C shape  21  of the lower shingle  70  interlocking with the C shape  22  of the upper shingle  71 . 
     As is best seen in  FIG. 5 , mounting tabs  50  protrude from top edge  11 . Mounting tab  50  has a top edge  51 , near which a hole  52  is located. The top surface  54  of the mounting tab  50  has an inclined portion  55  below the hole  52  so as to be raised above the roofing surface. A second level portion  56  is formed below the inclined portion  55 . The tab is then folded under the second level surface  56  so as to form a protrusion  57  at roughly a 45 degree angle to level surface  56 . The metal is then folded onto itself, along the underside of protrusion  57 . At this point, the metal is bent to form C shape  21  of metal shingle  10 , as exists along the remainder of the top edge of the metal shingle as shown in  FIG. 2 . The assembly is secured to the roofing surface by nailing through hole  52 . In the preferred embodiment, mounting bracket  50  is an integral part of metal shingle  10 . However, other embodiments are envisioned. In an attempt to optimize the use of sheet metal, the mounting tabs can be produced as separate pieces and secured to the metal shingles in a number of ways, such as, but not limited to, welding, pressure fitting, and gluing. Those skilled in the art will appreciate that although the mounting tabs  50  are preferred for securing each shingle to the roof, they are shown for illustrative purposes only and other means of securing the shingles to the roofing could be used without departing from the spirit and scope of the invention. 
     In the preferred embodiment, the metal shingle of the upper row “clicks” into place when interconnected with the metal shingle of the previous row.  FIG. 7  illustrates the relative placement of the two shingles when they are locked in place. Lower shingle  70  is attached to the roofing surface using mounting tab  50 . The C shape  22  of upper shingle  71  is appropriately positioned on lower shingle  70  and then moved toward C shape  21  of lower shingle  70  (i.e., upper shingle  71  is moved in the direction of arrow  75  in  FIG. 7 ). As it moves into position, top edge  12  contacts protrusion  57  of the lower shingle. Further movement of the upper shingle  70  causes the protrusion to contract, and once top edge  12  has moved past protrusion  57 , the protrusion will return to its natural position. Typically, as the protrusion returns to its natural position, a “click” will be heard and/or felt, thus alerting the installer that the shingles are properly interconnected. 
     Referring to  FIG. 4 , metal shingle  10  has a left, or trailing, edge  13 , which is not folded, except along the top edge  11  and bottom edge  12  as described above. The right, or leading, edge  14  is first turned up in the direction of the top surface  15  of the shingle. The right side is then bent to form an S fold  60  approximately 1.5 inches from the edge. This S fold  60  receives the left edge of the adjacent shingle.  FIG. 4  shows S fold  60  and upturned fold  61  at right edge  14 . The area between S fold  60  and upturned fold  61  creates a gutter  62  into which water that has leaked between adjacent shingles is captured. This S fold is created along the entire edge (length) of shingle  10 , including the areas where top edge  11  is folded over and bottom edge  12  is folded under. Thus, gutter  62  extends the entire length of the shingle. At the top edge  11 , the gutter  62  combines with overturn C shape  21 , as shown in  FIG. 8 . At the bottom edge  12 , the gutter combines with underturned C shape  22 , as shown in  FIG. 9 . Since the bottom edge  12  is underturned, water that has accumulated in the gutter  62  is able to spill onto the top surface  15  of the shingle in the lower row. 
       FIG. 8  is an exploded view of the upper right corner of shingle  10 . As described earlier, an S shaped fold  60  is created at a location spaced from the right edge. The right edge of the metal shingle is then folded to form upturned fold  61 . The space between the S fold on one side and the upturned right edge on the other side defines the gutter  62 . As a result, the particular spacing of the S shaped fold defines the width of gutter  62 . A unique feature of this roofing shingle is that both S fold  60  and upturned edge  61  are also incorporated in the bending operation that creates C shape  21  along top edge  11 . To create this shingle, the blank travels through a multi-station tooling die that performs the folding in a series of sequential operations. In each of the stations there is one or more folds being accomplished and in most instances work is being done to both the vertical and horizontal edges. The folding operation comprises a number of stations to complete the edges. 
     In many previous metal shingles, this gutter extended only to the point at which the C shape fold begins. With such conventional shingles, in severe weather conditions, water that is collected in the gutter can be blown upward. Therefore, since the C shape bend does not exist in traditional shingles, there is nothing to block this upward movement of the water. Thus, it simply drips off the top edge of the gutter and therefore contacts the roofing surface, resulting in potential leaks. 
       FIG. 9  is an exploded view of the lower right corner of shingle  10 . Gutter  62  is formed between S fold  60  and upturned edge  61 . Near the bottom of the metal shingle, the right edge meets the C shape  22  formed at the bottom edge  12 . As in the case of the upper right corner, the gutter is also formed into the same underturned C shape  22  as the rest of the bottom edge. Using this configuration, any water that is captured in the gutter  62  will be directed onto the top surface of the shingle in the adjacent lower row. This prevents leakage, as the water always remains on top of the shingles. 
       FIG. 10  illustrates the connection between two adjacent shingles in a row when installed on a roofing surface. The left edge  13  of right shingle  100  is inserted into the S fold  60 . The upturned right end  61  of left shingle  101  creates a barrier which prevents water from escape from the gutter  62 . Typically, upturned right end  61  contacts the bottom surface  16  of right shingle  100 , providing a further barrier to leakage between the mated shingles. 
     A second shortcoming to the metal shingle systems currently available is maintaining the aesthetic appearance of the roofing materials along the edge of the roof and around roof penetrations when the metal is terminated (cut), exposing an undesirable cut edge. This exposed cut must be hemmed or concealed to prevent rust from forming along the cut edge. Simply hemming the edge back on itself is not aesthetically accepted in residential roofing. Metal shingles are typically designed in such a way that the lower portion of the shingle is formed to sit above the roofing surface, while the upper portions rests directly on the roofing surface, as shown in  FIG. 3 . In this figure, the top surface of the shingle near C shape  21  rests directly on the roofing surface, while the top surface of the shingle near C shape  22  is elevated above the roofing surface. This gives the appearance of cascaded cedar shingles, where each rests on the one below it. A specific shortcoming with this implementation is the shape of the shingle near the edges, specifically when the shingle needs to be trimmed to fit into the desired space. 
     Traditional bending devices are made with long, flat edges. While preferable in most applications, it creates a misshaped, aesthetically displeasing edge on the shingle during installation. It is preferably that the shingle retains its asymmetric appearance, where it appears thicker toward the bottom edge than at the top edge. This is not possible using traditional flat edged bending devices. 
     A solution to this shortcoming is the development of bending devices, such as the pliers shown in  FIG. 11 , that are designed to bend the shingle in such a way so as to retain the asymmetric appearance as shown in  FIG. 13 . Preferably, this is done by having the thickness of either the upper or lower jaw of the pliers increase linearly from one side to the other. In this way, the edge is gripped by the pliers, which then bend the metal into two angles. As an example, using the pliers of  FIG. 11 , the metal shingle is gripped between the jaws, with the top surface of the shingle in contact with the lower jaw  150 . As shown in  FIG. 13 , this gripped portion becomes folded-under edge  170 . As the pliers are rotated downwardly with respect to the top surface of the shingle, a first angle  174  is created between folded-under edge  170  and sidewall  171 , which corresponds to the angle between the flat surface  152  and the front surface  153  of the upper jaw  151 . As the pliers continue rotating, a second angle  175  is created between sidewall  171  and top surface  176 , which corresponds to the angle between the front surface  153  and the top surface  154  of the upper jaw  151 . Since the upper jaw is thicker at end  156  than at end  155 , the shingle is bent such that it is thicker on that end than on the other. Thus, the sidewall  171  is thicker at end  173  than it is at end  172 , thereby preserving the asymmetric appearance of the shingle. Knowing that the shingle was placed in the pliers with its top surface in contact with the lower jaw, this plier is properly configured to create the proper angle when used on the left side of the metal shingle. 
     In order to properly bend the right edge of a metal shingle, it is necessary that a tool be created in which the upper jaw is formed with the thicker side at  155  and the thinner side at  156 . While possible, it presents a drawback to installers, who are now forced to carry two similar, but different, bending tools in order to properly install a metal shingle system. 
       FIG. 12  illustrates a second embodiment of these pliers.  FIG. 12  shows a single set of pliers that can be used to create a suitable bend for both the left and right edges of a metal shingle. Lower jaw  150  of the pliers remains unchanged in this embodiment. However, upper jaw  160  is modified. The upper jaw  160  increases in thickness from end  155  toward the center. Similarly, it increases in thickness from end  156  toward the center. Rotationally affixed to the center of upper jaw  160  is rotating block  161 . Rotating block  161  is designed to pivot about axis  162  such that it can positioned toward side  155  or on side  156 . Structurally, its lower edge is sloped downward at the same angle as the portion of the upper jaw upon which it rests. Its upper edge is sloped upward at the same angle as the portion of the upper jaw which remains exposed. In this manner, the rotating block  161 , in conjunction with the exposed portion of the upper jaw create a flat inclined surface. When the rotating block  161  is rotated to cover the previously exposed part of the upper jaw  160 , it creates a second inclined flat surface. By rotating the block in this manner, the pliers can be readily adapted to bend either side of the metal shingle. 
     As previously described, rotating block  161  has two utilitarian positions. Preferably, a mechanism exists by which the rotating block  161  is held in place in each of these positions. One such mechanism is illustrated in  FIG. 12 . In this embodiment, rotating block  161  is held in place via a fastener  163 , which extends through a hole  164  in the rotating block and a hole  165  in the upper jaw  160 . Preferably, a keyhole-shaped hole is used such that the fastener can fit through the hole and then slidingly engage. While this is the preferred embodiment, others are possible without departing from the spirit of the invention.

Summary:
A metal shingle system which is resistant to leakage, even under severe weather conditions. The key attribute of the new system to the design of the side edge of the shingle such that water that seeps between adjacent shingles cannot be blown upward. Briefly, the top edge is overturned and the bottom edge is underturned such that they can be interconnected as is well known in the art. One side edge is folded to form a gutter area into which water that seeps between laterally adjacent shingles is collected and drained onto the lower row of shingles. The top of the gutter area is blocked by the overturned top edge, which extends into the gutter region. Also disclosed is an improved tool for cutting the shingles, such as is needed around obstructions and at the end of the roofline.