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CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application No. 61/809,934 filed on Apr. 9, 2013. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention concerns rain gutters installed beneath roof eaves to collect rainwater runoff. The roof eaves sometimes form inside corners where roof sections pitched in different directions intersect, which requires an inside corner piece connected to straight gutter sections along each of the eaves forming the inside corner. A problem is created by an increased volume of rainwater runoff collected by a roof valley formed between the different roof sections. Since the increased flow volume directed into the inside corner piece causes overflow of rainwater over the top portion of the inside corner piece if it is not big enough to contain this increased volume. 
         [0003]    Various solutions have been proposed to eliminate such overflows such as diverter baffles and rain water distributors, as shown in U.S. Pat. Nos. 2,899,912; 2,120,395 and 7,765,743; and patent publication nos. US 2002/0124476; US 2001/0017008; US 2002/0124476; and US 2002/0152691. 
         [0004]    Such baffles and diverters are relatively expensive and add to the labor of installing a gutter system, and also often do not work well. 
         [0005]    Another solution which has been proposed is to increase the capacity of the corner piece by providing a front wall extending across the inside corner at a 45 degree angle which widens the corner piece, as shown in U.S. Pat. Nos. 6,883,760; 2,537,243 and 2,120,395. The inside corner pieces described in the latter two patents are adapted to a simple semicircular gutter configuration formerly used. 
         [0006]    In practice it has heretofore been too expensive to manufacture such 45° inside corner pieces matched to the standard curved and stepped shape of the front wall of roof gutters currently used and have not gained widespread commercial acceptance. 
         [0007]    It is an object of the present invention to provide such an increased capacity corner piece and method of manufacture which can be made at a low enough cost to be commercially viable. 
       SUMMARY OF THE INVENTION 
       [0008]    The above recited object of the invention and other objects which will be understood upon a reading of the follow specification and claims are achieved by an inside corner rain gutter piece having a curved and stepped front wall extending at 45° and configured to match the curved stepped shape of the front wall now in widespread use. Two similarly shaped wing sections are provided, one on each side of a front wall main section, the wing sections angled out from the front wall main section. 
         [0009]    A flat bottom panel extends back from the bottom side of the front wall to a pair of right angled upright walls each formed up from a side of the bottom panel and integral therewith. 
         [0010]    Preferably, a back wall extension piece is attached to short upright back walls to be substantially of the same height as the back wall of a standard gutter section while facilitating manufacture of the inside corner piece. 
         [0011]    A pair of straight gutter section each have an end received within a respective one of the pair of angled out wing sections of the front wall and are cut off to angle their ends, so as to have a bottom wall angled out to completely overlie the inside corner piece bottom panel and to be positioned against a respective back wall of the corner piece thereof to complete the connection of the straight gutter sections to the inside corner piece. 
     
    
     
       DESCRIPTION OF THE DRAWINGS  
         [0012]      FIG. 1  is a plan view of an inside corner formed by two intersecting roof eaves with a rain gutter inside corner piece according to the invention installed at the inside corner and the ends of two straight rain gutter sections connected thereto. 
           [0013]      FIG. 2  is a pictorial view from the front of an inside corner piece for a rain gutter according to the invention. 
           [0014]      FIG. 3  is a pictorial view from the rear of the inside corner piece for a rain gutter shown in  FIG. 2 . 
           [0015]      FIG. 4  is a plan view of the inside corner piece shown in  FIGS. 2 and 3 . 
           [0016]      FIG. 5  is a side view from the right of the inside corner piece shown in  FIGS. 1-4 . 
           [0017]      FIG. 6  is a plan view of the initial steps in making an inside corner piece for rain gutters according to the invention including cutting a blank from sheet aluminum. 
           [0018]      FIG. 6A  is an enlarged view of the blank cut out in the initial forming step with scrape areas shown covered with horizontal broken lines. 
           [0019]      FIG. 7  is a pictorial view of a next intermediate step in making the inside corner piece according to the invention. 
           [0020]      FIG. 8  is a pictorial view of a next intermediate step in making an inside corner piece according to the invention. 
           [0021]      FIG. 9  is a pictorial view of a next intermediate step in making an inside corner piece according to the invention. 
           [0022]      FIG. 10  is a pictorial view of a next intermediate step in making an inside corner piece according to the invention. 
           [0023]      FIG. 11  is an inverted pictorial view of a completed corner piece according to the invention. 
           [0024]      FIG. 12  is a pictorial view of an inverted partially completed inside corner piece according to the invention. 
           [0025]      FIG. 13  shows additional forming of the top portion of a front wall of an inside corner piece according to the invention. 
           [0026]      FIGS. 14A-14C  are pictorial views of several variations in the configuration of the top portion of the front wall of an inside corner piece according to the invention. 
           [0027]      FIG. 15  is a pictorial exploded view of an inside corner piece according to the invention with a fragmentary view of mating angled ends of straight gutter sections. 
           [0028]      FIG. 16  is a pictorial view of the inside corner piece shown in  FIG. 15  with the ends of straight gutter sections shown fit into respective sides of an inside corner piece according to the invention. 
           [0029]      FIG. 16A  is an enlarged front view of a corner piece according to the invention with fragmentary end portions of straight rain gutter sections installed therein. 
           [0030]      FIG. 17  is a view of the section taken in  FIG. 16 . 
           [0031]      FIG. 18  is an enlarged plan view of an inside corner piece shown in  FIGS. 15 and 16  with straight gutter sections ends being inserted into respective sides of an the inside corner piece according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
         [0033]    Referring to the drawings and particularly  FIGS. 1-5 , an inside corner piece  10  according to the invention is shown installed at an inside corner  12  formed by the intersection of two roof sections  14 ,  16  which are pitched in different directions so as to form a valley  18 . The valley  18  descends to the inside corner piece  10  so that rain water collected in the valley runs off into the inside corner piece  10 . 
         [0034]    The inside corner piece  10  includes an upright front wall  20  having a main section  22  extending at about a 45° angle to a pair of upright rear wall section  24 A,  24 B extending at right angles to each other. A pair of wing sections  26 A,  26 B are angled out from the main front wall section  22  so that each of these extend parallel to a respective rear wall section  24 A,  24 B. 
         [0035]    A flat bottom panel  28  joins the front wall main section  22  to the rear walls  24 A,  24 B to form the completed inside corner piece  10 . 
         [0036]    The wing sections  26 A,  26 B project out from respective ends of the main section  22  of the front wall  20  and beyond the sides  25  of the bottom panel  28  which each extend from a respective end of the front wall main section  22 . 
         [0037]    The front wall main section  22  and wing sections  26 A,  26 B each have a curved stepped shape in general conformity to the shape of the outer wall of gutters currently being installed. That is, a short vertical section  30  extends up from the bottom, with an integral formed sinuously curved intermediate section  32  extending up and out to a top portion  34  thereof. 
         [0038]    The front wall main section  22  may have a top portion  34  which projects straight up as seen in  FIGS. 2 and 3   
         [0039]    Each of the wing sections  26 A,  26 B is shaped in the same way, with a short vertical section  25 A,  25 B and stepped curved sections  27 A,  27 B. 
         [0040]    The top portion  36 A,  36 B or each of the wing sections  26 A,  26 B comprises a short vertical section  38 A,  38 B, a horizontal section  40 A,  40 B extending back towards a respective rear wall  24 A or  24 B and a short downwardly extending terminal edge  42 A,  42 B. This is the same shape as conventional gutter top portions only slightly larger so as to be able to slidably receive the ends of lengths of straight gutter sections, as described further below. 
         [0041]    The rear walls  24 A,  24 B are comprised of short upturned sides  34 A,  34 B integral with the bottom panel  28  and an extension piece  46  formed with two integrally connected sides  46 A,  46 B extended at a right angle to each other, and staked or riveted at  47  to a respective formed up rear wall side  34 A,  34 B to extend the rear walls  24 A,  24 B to the full height of a conventional rain gutter. 
         [0042]    The reasons for such a two piece construction is related to the cost of manufacture of the inside corner piece  10  as described in detail herein below. 
         [0043]    Referring to  FIGS. 6-13C , the manufacturing steps comprise cutting and forming operations preferably in a conventional progressive die set up. 
         [0044]    Sheet aluminum  48  is advanced from a roll of a width sufficient to allow a blank  50  to be cut therefrom (not shown) in a first step. 
         [0045]    The blank  50  has two narrow strip areas  52 ,  54  on the leading and trailing sides of the blank  50  respectively, projecting from a region  56  from which will be formed the bottom panel  28  of the inside corner piece  10  ( FIG. 6A ). 
         [0046]    A second strip of aluminum sheet  58  is fed off a roll (not shown) in a next step so as to underlie the trailing strip  54 . 
         [0047]    The width of the strip aluminum  58  corresponds to the finished height of the rear walls  24 A,  24 B. 
         [0048]    In the next step indicated in  FIG. 7 , the strip  58  is cut off to length to form a rear wall extension piece  59 , on end thereof staked or riveted to the underside of strip  54 . 
         [0049]    Simultaneously a front piece  60  of the blank  50  is formed into the curved stepped shape of the front wall  20 . The wing sections  26 A,  26 Bs are formed from the subregions  62 ,  64  of the blank  50 . The front wall  20  is also bent down along line  66  between regions  56  and  60  of the blank  50 . 
         [0050]    In the next step, the trailing strip  54  and attached extension piece  59  is formed down 90° as seen in  FIG. 8 . 
         [0051]    The projecting end  68  of the strip  54  is formed back 90° under the leading strip  52  aligned with one end  45  of the strip  54 , as shown in phantom lines in  FIGS. 8 and 9 . 
         [0052]    The leading strip  52  is then formed down and staked to the end  68  of extension piece  59 , thus forming the back walls  24 A,  24 B ( FIGS. 10 and 11 ). 
         [0053]    Referring again to  FIG. 6A , the blank  50  area  60  has a trapezoidal shape with a pair of sides A, B each sloping from the ends of an upper side C out to a longer lower side D (which constitutes fold line  26 ). 
         [0054]    This inclines the sides of parallelogram shaped areas  62 ,  64 . When the area  60  is being shaped in the curved stepped shape it is folded up along  66 D line  1  to be inclined up from the area  56  (forming the bottom panel  28 ), the areas  62 ,  64  are simultaneously also folded up when being shaped in the same way. Area  60  becomes the main section  22  of the front wall  20 . The areas  62 ,  64  at the same time are folded out in relation to the folded up area  60  to be parallel to fold lines F, G. This forms the wing sections  20 A,  20 B of the front wall  12 . 
         [0055]    The shape and position of areas  62 ,  64  causes the top edges H, Ito be moved to be parallel to the top edge C of the area  60 , and the bottom edges J, K to be parallel to the back walls  24 A,  24 B respectively. 
         [0056]    This results in the formed top portions  36 A,  36 B of the wing sections  26 A,  26 B to be aligned with the top portions and curved stepped front of the straight gutter sections  68 ,  70  ( FIG. 15 ) to allow them to be inserted into the inside corner side piece  10  as shown in  FIGS. 16 and 18 . 
         [0057]    The front wall main section  22  extends at about 45° to the back walls  24 A,  24 B and also to the installed straight gutter sections  68 ,  70 . 
         [0058]    This relationship creates an enlarged volume capacity of the inside corner piece  10  better able to contain the increased volume of rainwater runoff from the roof valley  18  ( FIG. 1 ). 
         [0059]    In order to minimize excessive scrap, lateral projections from the blank  50  are minimized, as can be seen in  FIG. 6A  where the areas of trimming scrap are indicated by horizontally broken lines. This is done here by minimizing both the length and the height of the short back walls  34 A,  34 B directly formed by the strips  52 ,  54  of the blank  50 . The width of the blank is reduced by first forming the short walls  34 A,  34 B and then attaching the separate back wall extension  46 A,  46 B to complete the back walls  24 A,  24 B. The length of the back walls is reduced by angling the floor panel sides L, M back towards each other rather than at 90° to the wing section  26 A,  26 B as seen in  FIG. 6A . 
         [0060]    This necessitates cutting mating ends of the mated straight gutter sections  68 ,  70  at an angle as shown in  FIGS. 15 ,  16  and  18 . 
         [0061]    The formed wing sections  26 A,  26 B slidably receive the shaped side of the straight sections  68 ,  70  which are advanced therein to the end of the respective wing section  26 A,  26 B. The straight section ends cannot be further advanced therein as they would create flow obstructions within the inside corner piece  10 . 
         [0062]    Since the length of the rear walls  24 A,  24 B does not extend out to be even with the end of the wing sections  26 A,  26 B, the straight sections must be cut along an angle of about 45° to overlap the bottom panel  28  and rear walls  24 A,  24 B as shown in  FIGS. 15 ,  16  and  18 . 
         [0063]      FIG. 11  shows the front wall  20  with the (inverted) top portion  34 ,  36 A,  36 B of the main section  20  and wing sections  26 A,  26 B yet to be formed. The forming of the portion can be done in a variety of ways, such as shown in  FIGS. 2 ,  3  and  13  in which the main section top portion  24  is left straight up and the tops of the wing sections  36 A,  36 B formed over to match the mating gutter straight sections, but a little larger in size to slidably receive the same therein. 
         [0064]      FIGS. 14A ,  14 B,  14 C show other possible variations with  FIG. 14A  showing the main section top portion  34 A formed over in a fashion similar to the top portions  36 A,  36 B of angled wing sections  26 A,  26 B. 
         [0065]    The slits  72  formed into the blank  50  ( FIG. 6A ) accommodate the separate forming of the top portions  36 A,  36 B,  34 A. 
         [0066]      FIG. 14B  shows the main section top portion  34 B formed straight out with formed over wing section tops. 
         [0067]      FIG. 14C  shows the main section top portion  34  left straight up and wing section top portions  36 C and  36 D formed straight out. 
         [0068]      FIGS. 15-18  show the connection of a inside corner piece  10  according to the invention to the two straight gutter sections  68  and  70  which would extend along the two roof eaves forming an inside corner. 
         [0069]    The straight gutter sections  68 ,  70  mate with an end of the inside corner piece  10  by the ends  78 A,  78 B sliding within a respective wing sections  26 A,  26 B and the rear walls  80 ,  82  thereof within the rear walls  24 A,  24 B ( FIG. 18 ). 
         [0070]    Since the wing sections  26 A,  26 B each extend substantially further out towards the respective straight sections  68 ,  70  than the rear walls  24 A,  24 B, the straight sections  68 ,  70  must be cut off at angle. If their ends were squared off, the ends would need to extend well into the inside corner piece  10  past the corners  74 ,  76  ( FIG. 13 ) which the wings  26 A,  26 B make with the main section  22  of the front wall  20 . This would create turbulence and flow resistance with water flow out of the two ends of the inside corner piece  10  and likely create leaks. 
         [0071]    Accordingly, the ends  78 A,  78 B of the straight sections  68 ,  70  are cut at an angle to locate the outer wall of each at the respective corners  74 ,  76  while each of the back walls  80 ,  82  thereof extend well past the ends of the back walls  24 B,  24 A as indicated in  FIGS. 15-18  creating sufficient overlap to enable a sealed connected to be made. 
         [0072]    Accordingly, the inside corner piece  10  can be made cheaply by conventional dies and minimal scrap to be commercially practical, thereby satisfying a long felt need in the industry.

Summary:
An inside corner piece for a rainwater gutter system having an angled front wall extending at a 45 degree angle to increase the amount of water able to be collected by the corner piece, with each end of a main section of the front wall having an angled out wing section slidably receiving an end of one of the straight gutter sections. The manufacturing method minimizes scrap by the shape of a blank used to form the corner piece