Abstract:
A system and method for cutting shingles according to which a plurality of cutting blades are mounted on the outer circumference of a cutting cylinder, and the cylinder is rotated with the blades engaging the sheet while effecting relative translational movement between the cylinder and the sheet so that eight unique shingles are cut from the sheet upon one rotation of the cylinder.

Description:
BACKGROUND  
       [0001]     This invention relates to a system and method for cutting individual objects, such as shingles, from a continuous sheet of material.  
         [0002]     In the mass production of composition, or asphalt, roofing shingles, a cutting cylinder is often positioned to engage a continuous sheet of a composition material that forms the shingles. Cutting blades are provided on the outer circumference of the cutting cylinder and the continuous sheet of material is passed under the cylinder as it is rotated to cut the shingles. In order to produce an attractive pattern, shingles have been cut in a “dragon tooth” pattern. However, when dragon tooth patterns are cut, a lack of variance in shingle patterns result in a non-random appearance when the shingles are applied to a roof, resulting in a relatively unsightly patterned appearance when compared to individual wood shingles, and the like.  
         [0003]     Therefore a system and method is needed to produce roofing shingles of the above type which are cut in a dragon tooth pattern yet increase both productivity and product appearance when compared to the techniques discussed above. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is an isometric view depicting an embodiment of the system of the present invention.  
         [0005]      FIG. 2  is an elevational view of eight shingles produced by the system of  FIG. 1 .  
     
    
     DETAILED DESCRIPTION  
       [0006]     Referring to  FIG. 1 , the reference numeral  10  refers to a strip of material that is used to produce shingles in accordance with an embodiment of the invention. It is understood that the strip 10  forms a portion of a continuous strip which is described in detail later. The strip  10  passes between two opposed cylinders  12  and  14  which are mounted for rotation in a conventional manner. One or both of the cylinders  12  or  14  is driven in any conventional manner to rotate the cylinders and drive the strip  10  in a longitudinal direction indicated by the arrows while being guided by edge guides, or the like (not shown), all in a conventional manner.  
         [0007]     A cutting blade  16   a  is mounted on the outer circumference of the cylinder  12  and is adapted to cut the strip  10  when it passes between the cylinders  12  and  14 . The cutting blade  16   a  extends for approximately one half the circumference of the cylinder, and a cutting blade  16   b  is also mounted on the outer circumference of the cylinder and extends from the cutting blade  16   a  around the remaining one half of the circumference of the cylinder.  
         [0008]     A cutting blade  18   a  is also mounted on the outer circumference of the cylinder  12  and extends in a spaced parallel relationship to the blades  16   a  and  16   b  for approximately one half the circumference of the cylinder  12 . A cutting blade  18   b  is also mounted on the outer circumference of the cylinder and extends from the cutting blade  18  and around the remaining one half of the circumference of the cylinder. A cutting blade  19  is also mounted on the outer circumference of the center portion of the cylinder  12  and extends around the entire circumference of the cylinder. The cutting blades  16   a,    16   b,    18   a,    18   b  and  19  are mounted on the cylinder  12  in any conventional manner.  
         [0009]     Although  FIG. 1  is not necessarily to scale, it is understood that the circumference of the cylinder  12  is substantially equal to twice that of the length of each shingle to be cut, and the cutting blades  16   a,    16   b,    18   a  and  18   b  are configured to cut four different dragon tooth patterns in the strip  10  upon one rotation of the cylinder  12 . Each dragon tooth pattern produces two shingles with complementary tabs and spaces between the tabs, which will be described. Therefore one rotation of the cylinder  12  produces eight unique shingles.  
         [0010]     During the cutting of the above patterns by the blades  16   a,    16   b,    18   a  and  18   b,  the center cutting blade  19  cuts the strip  10  longitudinally to separate the patterns cut by the blades  16   a  and  16   b  from the patterns cut by the blades  18   a  and  18   b.  It is understood that an end cutter (not shown) can be provided downstream from, and in a spaced relation to, the cylinder  12  for making transverse cuts in the strip to cut the strips into predetermined lengths.  
         [0011]      FIG. 2  shows examples of eight different shingles after being cut by the blades  16   a,    16   b,    18   a,    18   b  and  19 , and by the above end cutter in response to one rotation of the cylinder  12 , with the shingles being shown spaced apart in the lateral and longitudinal directions. In particular, two shingles  20  and  22  are formed by the dragon tooth cut made by the blade  16   a.  The shingle  20  includes four relatively narrow rectangular tabs  20   a,  and the shingle  22  includes four relatively wide rectangular tabs  22   a.    
         [0012]     Two shingles  24  and  26  are formed by the dragon tooth cut made by the blade  16   b.  The dragon tooth pattern cut by the blade  16   b  is such that the shingle  24  includes two relatively wide rectangular tabs  24   a  which are wider than the wide tabs  22   a  of the shingle  22 ; while the shingle  26  includes a tab  26   a  that is wider than the tabs  24   a  and a tab  26   b  that is wider than the tab  26   a.    
         [0013]     Similarly, two shingles  28  and  30  are formed by the dragon tooth cut made by the blade  18   a.  The latter pattern is such that the shingle  28  includes a relatively wide rectangular tab  28   a  extending between two relatively narrow tabs  28   b;  while the shingle  30  is formed with three rectangular tabs  30   a  of the same width as the tabs  28   b,  with two of the tabs  30   a  being spaced apart as a result of cutting the tab  28   a.    
         [0014]     Two shingles  32  and  34  are formed by the dragon tooth cut made by the blade  18   b.  The dragon tooth pattern cut by the blade  18   b  is such that both shingles  32  and  34  include four triangularly shaped tabs  32   a  and  34   a.    
         [0015]     As a result of the above, one rotation of the cylinder  12  produces eight different shingles  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 , and  34  all of which vary in appearance. Thus, when stacked and applied to a roof in sequence, a non-random, dimensional appearance is achieved rather than the unsightly patterned appearance of the prior art.  
         [0016]     It should be emphasized that the above configurations of the shingles are for the purpose of example only, and that the patterns can vary considerably from those that are shown. For example, the sizes and numbers of the tabs, as well as their width, length, and/or shape can vary from tab-to-tab and/or from shingle-to-shingle. Also, the patterns cut by the blades are not limited to a dragon tooth pattern but may take other forms, such as saw tooth, etc.  
         [0017]     According to a preferred method of applying the different patterned shingles  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 , and  34  to a supporting structure to form a roof, the shingles are laid in accordance with the following equation: 
 
 C=L/N± 3 
 
 where C is one of the course offsets, L is the length of each shingle, and N is the number of courses repeated during installation under the following conditions: 
        1. all of the shingles  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 , and  34  have a tooth covering the area C±3″ from the left side of the shingle     2. all of the shingles  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 , and  34  have a gap between teeth in the area C±3″ from the right side of the shingle, and     3. the sum of the offsets in the course repeat equal the shingle length.        
 
         [0022]     This provides a random appearance and insures that all the seams between adjacent shingles  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 , and  34  are covered for enhanced appearance and leak protection. Also, the above permits the shingles  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32 , and  34  to be applied using continuous offsets (e.g. 0. C, 2 C, 3 C . . . ) to obtain the same roof appearance as when the offsets repeat (e.g. 0, C, 2 C, 0, C, 2 C, etc.). Further, roofers can cut the shingles C inches from the right side of each shingle and never have to cut through a tooth and only one shingle needs to be cut every N courses when applying shingles of a rake edge which allows for easier application and less waste.  
         [0023]     It is understood that the strip  10  may be formed in a conventional manner such as by applying one or two asphalt coatings to a base material made from a mat of organic felt, fiberglass, polyester, or a blended fiberglass/polyester, and applying one or two outer layers of mineral granules to the asphalt coating(s). Further details of the composition of the strip  10  and the lamination technique are disclosed in U.S. Pat. No. 5,369,929 which is assigned to the assignee of the present invention and which is incorporated by reference. It is also understood that one or more backing strips (not shown) can be laminated to the strip  10  before the resulting laminated strip is cut in the foregoing manner. The backing strip may be identical to the strip  10  or may be different from the latter strip.  
         [0024]     It is understood that other variations may be made in the foregoing without departing from the scope of the invention. For example, the above-described relative movement between the cylinder  12  and the strip  10  can be achieved in other manners. Also, the spatial references, such as “over,” “under,” “longitudinal,” “lateral,” and the like, are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above.  
         [0025]     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many other modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.