You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to the field of removal of snow accumulation from a roof structure. More specifically, the present invention relates to a method and apparatus allowing for the safe and convenient removal of accumulated snow from a roof structure utilizing a lightweight snow removal knife.  
         BACKGROUND OF THE INVENTION  
         [0002]    In climates that experience winter conditions, it is common for snow to accumulate on roof structures. As this snow accumulates through either continued snowfall or through the action of wind, this snow accumulation can lead to a variety of problems to the structure. These problems can include possible damage to the structure as well as creating safety concerns for individuals who are using the structure.  
           [0003]    As the accumulated snow compresses and hardens, ice can form at the interface between the roof and the snow. This ice can result in ice dams, which prevents the roof from shedding moisture properly. The creation of ice dams ultimately leads to roof leakage and possible interior damage to the structure. Once the ice dam is formed, removal of the ice dam is typically accomplished through the physical labor of the structure owner. Removal of the ice dam necessarily puts the structure owner in an unsafe environment and typical removal methods can lead to further roof damage.  
           [0004]    Individuals can also be put into harms way when accumulated snow melts off the roof structure through heat radiated through the roof or because of warmer weather conditions or direct sunlight. As the snow melts, the water can drip off of the roof creating slippery conditions on any walkways surrounding the edge of the structure. Melting snow can also lead to the creation of icicles on roof overhangs. These icicles can lead to direct physical injury by falling on a passerby. Finally, as accumulated snow melts, large patches of snow can become dislodged and slide off the roof leading to inconvenience and possible injury to passersby.  
           [0005]    Because of the possible inconvenience and harm that accumulated snow can present on a roof structure, a variety of methods and tools have been developed to remove these accumulations.  
           [0006]    U.S. Pat. No. 3,091,790 discloses a snow removal device utilizing a multi-edged blade connected to an elongated handle. The blade is oriented so that in use, it is perpendicular to the roof surface. The user lifts the blade to as high a position on the roof as he can reach and proceeds to drag the snow down in his direction. The blade includes one edge with a flexible flapper to be used with fresh, loose snow. The blade also includes a toothed edge for use in removing built up ice.  
           [0007]    U.S. Pat. No. 3,483,643 discloses a snow removal device utilizing a pivoting blade assembly connected to a sectional handle. The device is designed so that the blade slides over the top of the accumulated snow as the user pushes the device to the peak of the roof. The user then pulls the device in a downward direction causing the blade to rotate and drag the accumulated snow downward toward the user.  
           [0008]    U.S. Pat. No. 3,773,375 discloses a snow removal device utilizing a blade connected to a sectional handle. The blade is oriented so that it is perpendicular to the plain of the roof. The blade is lifted above the snow surface and placed as high on the roof as the user can reach. The user then pulls the blade toward himself causing the snow to slide in his direction.  
           [0009]    U.S. Pat. No. 3,998,486 discloses a snow removal device utilizing a flexible, low-friction sheet. The sheet is attached to a rod having wheels at its ends. The rod being connected to a frame which is ultimately connected to a sectional handle. The device is placed at the edge of the roof and the user pushes the device up the roof and through the snow. The rod is designed to undercut the snow that then slides down the low-friction sheet in the direction of the user.  
           [0010]    U.S. Pat. No. 4,024,654 discloses a snow removal device using a blade with two pulling devices. The first pulling device is used to pull the blade to the top of the roof by pulling from the opposite side in which you intend to remove the snow. When the blade reaches the top of the roof, the user moves to the side of the structure in which it is desired to remove the snow. The user pulls on the second pulling device to drag the blade through the snow. This results in the snow being slidably removed in the direction of the user.  
           [0011]    U.S. Pat. No. 4,089,127 discloses a snow removal device utilizing a chute attached to an elongated handle. The device is placed on the edge of the roof and the user applies a bias to the handle resulting in the chute moving up and through the snow accumulation. The dislodged snow slides down the chute in the direction of the user.  
           [0012]    U.S. Pat. No. 6,092,315 discloses a snow removal device having a wheeled frame and slide attached to an elongated handle. The wheeled frame is placed at the edge of the roof and the user biases the wheeled frame to the peak of the roof. The frame cuts through the accumulated snow causing it to slide down the chute in the direction of the user.  
           [0013]    A wide variety of prior art concerned with various snow shovel and scoop designs exists including U.S. Pat. No. 195,198 disclosing a method to increase the strength and efficiency of snow shovels, U.S. Pat. No. 941,271 disclosing a strong but inexpensive snow shovel design, and U.S. Pat. No. 2,752,631 disclosing a combination shovel and snow mold assembly.  
           [0014]    Each of the aforementioned systems for snow removal from roofs suffers from disadvantage. Use of some of these designs can lead to shingle and roof structure damage. Nearly all of the designs call for the snow to be removed through a sliding action in the direction of the user. These designs are also unwieldy leading to difficulties in lifting, manipulating and operating the devices. What is needed is a device that overcomes the limitations of the prior art.  
         SUMMARY OF THE INVENTION  
         [0015]    The snow removal device of the present invention overcomes the limitations of the aforementioned devices by providing a lightweight device that can be directed to undercut the snow pack disposed on the roof without disadvantageously engaging roof shingles.  
           [0016]    The present invention is a snow removal knife including a knife assembly operably, disengagably connectable to a handle assembly and having a pole interface disposed on a knife assembly upper margin, the knife assembly presenting a substantially planar knife assembly lower margin and having a distal cutting edge, the cutting edge being non-coplanar with the knife assembly lower margin, the cutting edge being upwardly directed relative to the knife assembly lower margin to define a roof engaging surface proximate an intersection of the knife assembly lower margin and the distal cutting edge. The present invention further includes a method of forming the snow removal knife. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view of the snow removal knife of the present invention;  
         [0018]    [0018]FIG. 1 a  is a sectional view of the distal edge of the snow removal knife taken through the snow removal knife center axis;  
         [0019]    [0019]FIG. 2 is a top view of the knife assembly;  
         [0020]    [0020]FIG. 3 is a side view of the distal edge of the knife assembly;  
         [0021]    [0021]FIG. 4 is an enlarged side view of the distal edge of the knife assembly;  
         [0022]    [0022]FIG. 5 is a schematic drawing of a structure having a snow-covered roof;  
         [0023]    [0023]FIG. 6 is a schematic drawing of the structure in which a user has begun using the snow removal device;  
         [0024]    [0024]FIG. 7 is a schematic drawing of the structure in which the user has cleared less than half of the roof with the snow removal device;  
         [0025]    [0025]FIG. 8 is a schematic drawing of the structure in which the user has cleared more than half of the roof with the snow removal device; and  
         [0026]    [0026]FIG. 9 is a schematic drawing of the structure in which the user has cleared the roof with the snow removal device;  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    A snow removal knife according to an embodiment of the present invention is illustrated at  100  in FIG. 1. The snow removal knife  100  of the present invention includes a lightweight elongated handle assembly  110 , a gripping portion  120  and a knife assembly  130 .  
         [0028]    The handle assembly  110  preferably includes extension means allowing a user to increase the reach of the snow removal knife  100 . The gripping portion  120  provides the user was a safe and sure grip of the snow removal knife  100 . The knife assembly  130  is designed such that the snow removal knife  100  can exhibit a slicing action when moved in either a vertical or horizontal orientation.  
         [0029]    The design of the present invention provides a number of user enhancements that are not exhibited by prior art snow removal devices. The lightweight design requires less strength on the part of the operator to lift and operate the device. The gripping portion  120 , if constructed from an electrically insulating material, can provide a measure of safety to the user when power cables and wires are located in the vicinity of the roof structure. Finally, the ability to laterally slide the snow removal knife  100  allows a user to clear snow in a manner that prevents sliding snow from falling upon the user.  
         [0030]    The handle assembly  110  is constructed of lightweight materials and includes a series of hollow, pole sections  140  adapted for quick interconnection with one another. One end of the pole section  140  is preferably designed with a protrusion  150  having an outside diameter that is slightly less than the inside diameter of an end of another pole section  140 . When mated to the knife assembly  130 , the handle assembly  110  is coincident with the center axis  112  of the snow removal knife  100 .  
         [0031]    The protrusion  150  preferably includes a spring loaded locking mechanism  160  that is compressed as the protrusion  150  is inserted into the pole section  140 . On each pole section  140 , the end opposite the protrusion  150  includes a small diameter bore  170  that is slightly larger than the spring loaded locking mechanism  160 .  
         [0032]    As the protrusion  150  is inserted into the hollow end of the second pole section  140 , the spring loaded locking mechanism  160  is released into the small diameter bore  170  effectively the locking pole sections  140  together. This process can be repeated for any number of pole sections  140  depending upon the desired length of the snow removal knife  100 .  
         [0033]    The pole sections  140  can be separated by forcibly depressing the spring loaded locking mechanism  160  and sliding the protrusion  150  out of the hollow end of the pole section  140 . The pole sections  140  may be manufactured of aluminum but a suitable electrically non-conductive material that is both lightweight and possessing sufficient strength and rigidity could be used. This may be a plastic, fiberglass, or other non-metallic material.  
         [0034]    The gripping portion  120  consists of a tubular section that can optionally be of an electrically insulated material. A rubber handgrip  180  is placed over one end of the gripping portion  120 . The other end includes a protrusion  150  with spring loaded locking mechanism  160 . The protrusion  150  is inserted into the hollow end of the pole section  140 . The spring loaded locking mechanism  160  on the gripping portion  120  interacts with a small diameter bore  170  on the pole section  140  effectively locking the two pieces together. The gripping portion  120  is preferably constructed of a lightweight metal such as aluminum, or can be made from fiberglass or any other suitable non-conducting material possessing sufficient strength and rigidity.  
         [0035]    The knife assembly  130 , which is illustrated in FIGS.  1 - 5 , preferably comprises a precision-machined laminate sheet  190 . The laminate sheet  190  is generally planar and has four edges, comprising a distal edge  200  furthest from the gripping portion  120 , a proximal edge  210  nearest the gripping portion  120 , and two spaced apart generally parallel side edges  220 . The distal edge  200  may be gently curved, bending back toward the points of intersection with the two spaced apart generally parallel side edges  220 . The laminate sheet  190  has an upper margin  222  and an opposed lower margin  227 . The lower margin  227  is generally planar so that the lower margin presents no raised surfaces to disadvantageously engage the shingles of the roof.  
         [0036]    Referring to FIGS. 1 and 1 a , the distal edge  200 , the proximate edge  210 , and the side edges  220  each contain a cutting edge  225 . The cutting edge  225  of the distal edge  200  comes to a radiused tip  226 . The cutting edge  225  is directed upward to define a beveled surface  228  so that the actual tip  226  is elevated relative to the bottom margin  227  when the bottom margin  227  is in a generally horizontal disposition. By elevating the tip  226 , a roof engaging surface  223  is defined proximate the intersection of the beveled surface  228  and the lower margin  227 , the actual location of the engaging surface  223  being a function of the angle of the lower margin  227  with the plane of the roof. The elevated tip  226  thereby slides over roofing shingles without catching and causing any damage to either the knife assembly  130  or the roof.  
         [0037]    A plurality of spaced apart, generally parallel strengthening strakes  229  extend rearward from the tip  226  on the upper margin  222 . The strakes  229  are tapered and gradually blend into the upper margin  222 .  
         [0038]    The laminate sheet  190  is designed so that the cross-section of the laminate sheet  190  tapers from a maximum sheet thickness at the proximate edge  210  to a minimum sheet thickness at the distal edge  200 . The tapered edge design provides for a minimum cross-section at the cutting edge  225  on the distal edge  200  and a maximum cross-section at the cutting edge  225  at the sweeping interface of the proximate edge  210 .  
         [0039]    The laminate sheet  190  preferably includes a molded pole interface  230  disposed on the upper margin  222  so as to leave the lower margin  227  planar. The pole interface  230  has small a diameter bore  240  sized to interface with the spring loaded locking mechanism  160  found on the protrusion  150  of the pole section  140 . The knife assembly  130  is both bendable and resilient, such that it resumes its original shape after being deflected from the original shape.  
         [0040]    The knife assembly  130  is preferably constructed of a high density polyethylene material or a high density polycarbonate material such as Lexan plastic, but any suitable high-impact plastic possessing qualities including lightweight, strength, and resilience could be used.  
         [0041]    The use of the snow removal knife  100  is depicted in FIGS.  5 - 9 . During use of the snow removal knife  100 , a user  240  assembles the snow removal knife  100  to the proper length by attaching the gripping portion  120  and the knife assembly  130  to the desired number of pole sections  140  via the spring loaded locking mechanisms  160 .  
         [0042]    The user  240  then lifts the knife assembly  130  to the base of structure roof  250  that is covered in snow  260 . The user  240  proceeds to push the knife assembly  130  up the structure roof  250 , such that the knife assembly  130  is generally parallel to the roof surface and is riding just above the roof surface and under cutting the bulk of the snow pack on the roof.  
         [0043]    The knife assembly  130  may also be employed in a generally orthogonal disposition relative to the roof surface to make generally parallel cuts through the depth dimension of the snow pack on the roof. By doing this before undercutting the snow pack as noted above, the undercutting action then results in discrete blocks of the snow pack being dislodged, a pair of generally parallel, spaced apart, depth cuts defining the edges of the discrete block.  
         [0044]    The distal edge  200  of the knife assembly  130  slices any bond between the snow  260  and the structure roof  250 . When the bond is broken, the snow  260  slides off the structure roof  250  by means of gravity. The user  240  can also rotate the gripping portion  120  in a lateral motion. This allows the high impact knife assembly  130  to travel sideways across the structure roof  250  while the user  240  maintains a stationary position. In this manner, the user  240  can cause the snow  260  to be removed from the structure roof  250  with no danger of the snow  260  falling upon the user  240 .  
         [0045]    Through the use of the spring loaded locking mechanism  160 , the present invention can be disassembled into individual pieces for storage when not in use. The modular design also allows for quick, easy and inexpensive replacement of any components that have worn or broken during use.  
         [0046]    It is contemplated that features disclosed in this application, as well as those described in the above applications incorporated by reference, can be mixed and matched to suit particular circumstances. Various other modifications and changes will be apparent to those of ordinary skill.

Summary:
A snow removal knife includes a knife assembly operably, disengagably connectable to a handle assembly and having a pole interface disposed on a knife assembly upper margin, the knife assembly presenting a substantially planar knife assembly lower margin and having a distal cutting edge, the cutting edge being non-coplanar with the knife assembly lower margin, the cutting edge being upwardly directed relative to the knife assembly lower margin to define a roof engaging surface proximate an intersection of the knife assembly lower margin and the distal cutting edge. A method of forming the knife is further included.