Patent Publication Number: US-2007110527-A1

Title: Hole saw slug removal device

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application is being filed as a continuation-in-part of U.S. patent application Ser. No. 10/81 7,944, filed Apr. 6, 2004. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to slug removal devices and, more specifically, to a hole saw slug removal device used to automatically eject plugs that have been sawed from material.  
      2. Description of the Related Art  
      A hole saw is a type of saw used in drilling circular holes in various materials, such as wood, metal, drywall, etc. The hole saw typically has a cylindrical body, one edge of which is serrated. In addition, the cylindrical body contains openings at both ends that allow for a drill bit to be extended therefrom. The drill bit juts out just beyond the serrated edge and stabilizes the hole saw against the surface of the material. When used with a drill power source, the serrated edge of the hole saw body rotates, creating circular holes in the material.  
      A substantial problem that is faced in employing the hole saw to drill holes in a surface is that the waste left over, typically called a slug, is difficult to extract from within the body of the hole saw. The user is required to stop after each hole is sawed and manually extract the slug from the hole saw. This manual slug removal technique is time-consuming and takes substantial effort for the user. Thus, a hole saw that allows for quick removal of the slug provides much greater use for the user. Automatic removal of the slug would be preferential to non-automatic slug removal.  
      The related art endeavors to solve the problem of slug removal by either developing different types of hole saws to eject the slugs or by developing a slug removal device to be connected to the hole saw.  
      U.S. Pat No. 3,390,596, issued Jul. 2, 1968 to Trevathan, discloses a cutting head assembly that may be utilized to bore circular holes. The cutting head assembly has a cylindrical body with a plurality of cutting teeth on one edge of the body. The plurality of cutting teeth appear to preferably consist of inwardly and outwardly extending teeth. A spring is positioned within the body portion, and a spring-actuated disc is inserted within the cylindrical body, the disc being used to decrease distortion in the hole shape. The disc and spring appear to be held within the cylindrical body of the cutting head assembly by the inwardly extending teeth. When attached to a power source, the cutting head assembly is rotatably driven about its axis such that a hole is cut into the surface of the material on which it is placed.  
      U.S. Pat No. 4,652,185, issued Mar. 24, 1987 to Malrick, shows a hole saw and slug-removing device. The hole saw has a cylindrical body through which a drill bit may pass, one edge o the cylindrical body being serrated such that when the hole saw is used, a circular hole is drilled into a surface. A plug member is positioned within the hole saw using a set of screws inserted through an annular collar and into the plug member. The screws maintain the plug member within the hole saw. It appears that a spring may be positioned within the hole saw between an inner portion of the hole saw and the plug member and become compressed when the hole saw is operated. After the hole has been made, the hole saw operator may extract the slug from within the hole saw by manually pressing down on the annular collar.  
      U.S. Pat. No. 5,816,752, issued Oct. 6, 1998 to Benjamin, describes a slug removal system. The system includes a knockout device that ejects slugs after a hole is drilled using a hole saw. The knockout device has a cylindrical body, which is tapered at one end, and fits inside the hole saw. A spring is included as part of the slug removal system. As the hole saw is used, the knockout device is pushed back against the spring. When the hole is completed, the spring decompresses, ejecting the slug from within the hole saw. A set of screws secures the knockout device to the hole saw at predetermined depths.  
      Although the related art does address devices for slug removal, what is needed is a simple device, easily constructed, that automatically removes slugs. What is further needed is a device for slug removal that may be attached to hole saws that lack a slug removal device. The device should allow for simple insertion within the body of a hole saw and should not require the addition of attachment means that are situated on the outside of the hole saw body. Further, it is advantageous to have a slug removal device that may be removed and later reattached to a hole saw.  
      None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a hole saw slug removal device solving the aforementioned problems is desired.  
     SUMMARY OF THE INVENTION  
      The hole saw slug removal device is a center device constructed to fit within a hole saw. The slug removal device provides for automatic ejection of waste slugs from within the body of the hole saw. The hole saw slug removal device generally includes a compression spring fixed between two discs, the discs being affixed to the spring. The device is then inserted within the hole saw. Upon operation of the hole saw, the spring compresses, and one disc is pushed down by the force of the sawing. After sawing is completed, the spring decompresses, and the disc is pushed up. The disc then automatically ejects the waste slug that has become trapped within the hole saw.  
      In one embodiment, the disc to be inserted into the hole saw has a center opening with internal teeth and is convexly shaped. The hole saw slug removal device is pressed into the hole saw, and when the user determines, the device will lock into the hole saw by latching against the drill bit. In another embodiment, the disc to be inserted into the hole saw has external teeth and is concavely shaped. Following depression into the hole saw, when the user determines, the device locks into the hole saw by latching against the hole saw body. In another embodiment, the lower disc is omitted and the hole saw slug removal device with the spring and one top disc is permanently affixed to the bottom of the hole saw.  
      One aspect of the invention is that the hole saw slug removal device provides for automatic removal of waste slugs in contrast to more time-consuming manual removal of the slugs. Another aspect of the invention is that the hole saw slug removal device may be provided as a separate piece from the hole saw. It may be purchased at a separate time from the hole saw, then inserted and “locked” within the hole saw for convenient slug removal. In one embodiment, the device may be removed from the hole saw, so that the slug removal device may be reused. A further aspect of the invention is that the slug removal device has a simple design, allowing for minimal expense in the construction of the device. The simple design lacks additional costly or obtrusive elements such as screws or the like to attach the slug removal device to the hole saw.  
      In another embodiment, the hole saw slug removal device extends to the combination of a pilot bit and a resilient slug ejection assembly as described above, the pilot bit having an annular groove defined in the shank that is resiliently engaged by the internal teeth of the bottom or proximal disc. The compression spring may be a helical spring having coils of progressively smaller diameter extending from the bottom disc to the top or distal disc, giving the helical spring a frustoconical shape. This gives the outer diameter of the coils adjacent the top disc, which bears against the slug, more room to expand within the hole saw as the spring is compressed in order to prevent the spring from binding in the hole saw.  
      The invention provides improved elements and arrangements thereof for the purposes described and is inexpensive, dependable and fully effective in accomplishing its intended purposes.  
      These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an elevational side view of a hole saw and hole saw slug removal device, partly in section, according to a first embodiment of the present invention.  
       FIG. 2  is a perspective view of the hole saw and hole saw slug removal device as shown in  FIG. 1 .  
       FIG. 3  is an exploded, perspective view of the hole saw slug removal device of the first embodiment.  
       FIG. 4  is an elevational side view of a hole saw and hole saw slug removal device, partly in section, according to a second embodiment of the present invention.  
       FIG. 5  is an exploded, perspective view of a hole saw slug removal device of the second embodiment.  
       FIG. 6  is an elevational side view of a hole saw and hole saw slug removal device, partly in section, according to a third embodiment of the present invention.  
       FIG. 7  is an exploded, perspective view of a fourth embodiment of a hole saw slug removal device according to the present invention. 
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings.  
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is a hole saw slug removal device, designated generally as  10  in the drawings. The hole saw slug removal device  10  is designed to fit inside a hole saw  12 , as shown in  FIGS. 1, 2  and  4 . The hole saw  12  includes a cylindrical body  14  having two openings to allow for a drill bit  30  to be inserted therein. A serrated edge  16  of the cylindrical body  14  is used for cutting into a material surface  60 .  
      Referring first to  FIG. 3 , the hole saw slug removal device  10  is shown with a drill bit  30 . The slug removal device  10  allows for the drill bit  30  to fit within the device  10 . The drill bit  30  guides the hole saw  12  against a surface  60  of the material to be cut. The slug removal device  10  is made up of a compression spring  20  fixed between two discs  22  and  24 . The top disc  22  is a disc of any type, for example, a washer, and may be flat or shaped in a different manner. The top disc  22  may be permanently attached to an end of the spring  20 . A bottom disc  24 , which may be a washer, may be permanently affixed to the other end of the spring  20 . The top  22  and bottom  24  discs may be annular. Both discs  22  and  24  have a hole in the center to allow for the drill bit  30  to fit through each disc  22  and  24 .  
      As shown in  FIGS. 1 and 4 , the bottom disc  24  serves as a locking mechanism with which to retain the compression spring  20  within the hole saw  12 . The bottom disc  24  contains a means for retaining the compression spring  20  within the hole saw  12 . In one embodiment, shown in  FIG. 1 , a means for retaining the compression spring  20  within the hole saw  12  is a set of inner teeth  26  of the bottom disc  24  that lock the slug removal device  10  onto an outer portion of the drill bit  30 . As shown in  FIGS. 1 and 3 , the bottom disc  24  is convexly shaped. In another embodiment, shown in  FIG. 4 , a means for retaining the compression spring  20  within the hole saw  12  is a set of outer teeth  28  of the bottom disc  24  that lock the slug removal device  10  onto an inner surface of the cylindrical body  14  of the hole saw  12 . As shown in  FIGS. 4 and 5 , the bottom disc  24  is concavely shaped.  
      Following use of the hole saw  12 , the hole saw slug removal device  10  may be removed from the hole saw  12 , depending on the type of disc used. For example, if a convex inner-toothed bottom disc  24  is utilized, as in  FIG. 1 , after the drill bit  30  is disconnected from the hole saw  12 , the slug removal device  10  may easily slip out of the hole saw  12 . In contrast, if a concave outer-toothed bottom disc  24  is utilized, as in  FIG. 4 , even after the drill bit  30  is removed from within the hole saw  12 , the slug removal device  10  will stay lodged within the hole saw  12 .  
      As shown in  FIGS. 1, 2 , and  4 , after the hole saw slug removal device  10  is inserted within the hole saw  12 , an arbor  40  is used to attach the hole saw  12  to a portable drill for powering the hole saw  12 . When operated, the hole saw  12  cuts into a surface, such as drywall or the like. The top disc  22  is depressed, compressing the spring  20 . A volume of waste material, or slug, then becomes wedged into the hole saw  12 . Following operation of the hole saw  12 , the spring  20  decompresses and the top disc  22  is forced out of the hole saw  12 . The slug is then automatically ejected from within the hole saw  12 .  
      Alternatively, as illustrated in  FIG. 7 , the drill bit  30 , which is a pilot bit for a hole saw, may have an annular groove  100  formed along the outer surface thereof above the fluted cutting edges of the bit  30  and below the flat(s) on the upper portion of the shank that the arbor&#39;s set screw bears against. It will be understood that hole saw pilot bits come in a variety of configurations, and may be provided with a single flat or a plurality of flats that may be engaged by the set screw, and the flats may extend continuously along the entire length of the upper shaft, or may be formed in one or more discrete notches. For example, the upper portion of the shank may be octagonal, hexagonal, or cylindrical through about 270° of its circumference, with a flat being formed across the remaining 90°, the flats being continuous along the length of the upper portion of the shaft so that the arbor may be adjustably positioned along the shaft in order to adjust the length of fluted cutting edges extending below the teeth of the cylindrical hole saw body  14 . Alternatively, the upper portion of the shank may be cylindrical, with a flat formed in one notch for use with a single hole saw. The upper portion of the shank of the pilot bit  30  of the present invention may have any of these configurations, the annular groove  100  being disposed between the flat(s) on the upper shank and the fluted cutting edges of the bit  30 .  
      The inner circumference  110  of bottom disc  24  may be positioned within groove  100  of the drill bit  30 , the internal teeth  26  resiliently engaging the groove  100 , allowing for secure positioning of the device  10  with respect to the drill bit  30 , and allowing the device  10  to rotate freely with the bit  30 . In  FIG. 7 , the spring  20  is shown as having a substantially frustoconical side profile, with the diameter of the helix forming spring  20  adjacent the bottom disc  20  being greater than diameter the diameter of the helix adjacent the top disc. The annular top disc  22  is slidable over the fluted cutting edges of pilot bit  30 , so that the slug bears against top disc  22  and compresses spring  20  as the teeth of cutting cylinder  14  penetrate work surface  60 . When the hole saw  14  is withdrawn from the work surface,  60 , compression spring  20  expands, thereby ejecting the slug from cylindrical body  14 . The tapered, frustoconical shape of compression spring  20  allows room for the coils adjacent top disc  22  to expand laterally as spring  20  is compressed within cylindrical body  14 , preventing the spring  20  from binding against the wall of cylindrical body  14  and ensuring ejection of the slug.  
      In another embodiment shown in  FIG. 6 , the hole saw slug removal device  10  is permanently attached to the hole saw  12 . According to this embodiment, the slug removal device  10  consists of the compression spring  20  and the top disc  22 , which is attached to one end of the compression spring  20 . The other end of the compression spring  20  is permanently affixed to the bottom end  18  of the hole saw  12 . When the hole saw  12  is operated, the top disc  22  is depressed further into the hole saw  12  by the force of the sawing, compressing the spring  20 . A waste slug becomes lodged into the hole saw  12 . After the sawing is completed, the compression spring  20  presses the top disc  22  forward and the waste slug is automatically ejected from the hole saw  12 .  
      Preferably, device  10  is formed from stainless steel, which is then electro-polished. The elements forming device  10 , i.e., discs  22  and  24  and spring  20 , are preferably laser-welded together. It will be understood that instead of resilient teeth  26 , bottom disc  24  may have any other means for resilient engaging drill bit  30 , e.g., a spring-biased detent mechanism.  
      It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.