Abstract:
A sanding device for performing sanding operations comprising a core carrying a plurality of bristles and a plurality of pieces of abrasive cloth, wherein within said core is a material comprising a filler material and a binding material.

Description:
[0001]    The invention relates to a device for performing sanding operations, the sanding device comprising: a core having a surface; a plurality of bristles being secured to said core and extending from said surface; and a plurality of pieces of abrasive cloth extending from the surface. 
       BACKGROUND OF THE INVENTION 
       [0002]    Sanding devices are used among others within the woodworking, metal, plastic and furniture industries and may be used for surface treatment or sanding of plane and curved surfaces for providing smooth surfaces. Sanding devices usually comprise a combination of brushes and sanding means. The function of the brushes is to ensure a certain application pressure between the sanding means and the items to be sanded. 
         [0003]    U.S. Patent application No. 2003/0092370 discloses a sanding strip for use with a sanding wheel. The sanding strips are anchored in undercut grooves in a sanding wheel thereby comprising a sanding device. The disclosed sanding strip comprises a profiled rail wherein a line of bracing elements or brushes is secured. Sanding means are secured to one side of the line of brushes by means of glue. 
         [0004]    In a sanding device the expected life time of the sanding means is usually way below the life time of the brushes. When the sanding means have been worn down either the entire sanding device or only the sanding means have to be replaced. When the uptime of a production line is crucial, it is undesirable to waste valuable time on changing sanding means one by one. Changing and discarding of known sanding device may be both economically and environmentally undesirable. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention seeks to provide an improved sanding device wherein the properties of the core may be customized according to specific requirements for the sanding device. 
         [0006]    This is achieved by the device comprising a core having a surface; a plurality of bristles being secured to the core and extending from the surface; a plurality of pieces of abrasive cloth extending from the surface; wherein the core is made from a material comprising a filler material and a binding material. The core may be solid or it may be a cylindrical shell. 
         [0007]    An advantage in this respect is that the properties of the core material may be varied according to the specific construction of the sanding device. By using different types of filler material, binding material and combinations thereof the core may be of lighter weight, less expensive to produce, easier to dispose of, etc. The core may also be designed in accordance with means for securing bristles and/or pieces of abrasive cloth to the core. 
         [0008]    In one embodiment, the filler material comprises a recycled material. Hereby the sanding device, particularly the core, may be less expensive to produce, and the sanding device may de disposed of in an environmental-friendly way. 
         [0009]    In another embodiment the pieces of abrasive cloth are secured to the surface by use of staples extending through the abrasive cloth and into the core. Hereby the pieces of abrasive cloth are secured to the core by simple and inexpensive means. The pieces of abrasive cloth may be easily changed without the use of advanced tools. The staples may be the only means for securing the pieces of abrasive cloth; alternatively the staples may be used in combination with glue for securing the pieces of abrasive cloth while the glue is curing. Velcro tape may also be used. 
         [0010]    In another embodiment, reinforcement strips are arranged on top of the pieces of abrasive cloth, and the staples extend through the reinforcement strip, the abrasive cloth and into the core. An advantage in this respect is that the reinforcement strip prevents tearing of the abrasive cloth by the staples, when forces are applied to the cloth. 
         [0011]    In another embodiment, the pieces of abrasive cloth are secured to the surface or to the bristles by use of glue. Hereby staples may be applied only for securing the abrasive cloth during curing of the glue. If staples are use in a combination with glue, the construction may be strengthened, tear of the abrasive cloth may be prevented, and the number of staples may be reduced. 
         [0012]    In a still further embodiment, the abrasive cloth is secured to the sanding device  1  by gluing and/or stapling of the abrasive cloth to the bristles. In this embodiment, the abrasive cloth need not be secured to the surface of the cylindrical core. 
         [0013]    In a still further embodiment, the core comprises grooves adapted to receive and secure pieces of abrasive cloth and bristles. By utilizing grooves, the abrasive cloth and/or bristles may be arranged in fastening strips adapted to be inserted in the grooves. A fastening strip may comprise several bristles or pieces of abrasive cloth arranged side by side. By utilizing fastening strips, the abrasive cloth and/or bristles may be changed faster. 
         [0014]    In another embodiment, the sanding device comprises different pieces of abrasive cloth with different grit sizes. Hereby the sanding device has one grit size when it is rotated in one direction and another or the same grit size when it is rotated in the opposite direction. 
         [0015]    Instead of a single layer of abrasive paper, it is an option according to one embodiment that two or more layers of abrasive paper are provided, like a sandwich. When the outermost layer is worn, the layer behind will overtake the sanding. 
         [0016]    According to another embodiment, several rows of bristles may also be provided between two pieces or two sandwiches of abrasive paper, to the effect that two or three bristles, seen in the peripheral direction, support the abrasive paper. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for exemplary purposes only and should not be used to limit the scope of the invention. 
           [0018]      FIGS. 1   a, b, c  illustrate different ways of securing abrasive cloth to a sanding device. 
           [0019]      FIGS. 2   a, b  are perspective views of cylindrical cores with differently arranged holes. 
           [0020]      FIG. 3  is a perspective view of a cylindrical core with holes and only one row of extending bristles. 
           [0021]      FIG. 4  is a perspective view of a cylindrical core with only one section of abrasive cloth secured to the surface of the core. 
           [0022]      FIG. 5  illustrates end pieces for the sanding device. 
           [0023]      FIG. 6  illustrates a disc-shaped sanding device according to one embodiment of the invention. 
       
    
    
     DESCRIPTION 
       [0024]    With reference to the drawings a sanding device  1  comprising an elongated cylindrical core  10 , a plurality of bristles  12 , and pieces of abrasive cloth  11  will be described in the following. 
         [0025]    The cylindrical core  10  has a surface  20  with a plurality of holes  21 . In the embodiments shown, the cylindrical core  10  is hollow with an appropriate wall thickness. The cylindrical core may be manufactured from a material comprising a filler material and a binding material. 
         [0026]    The filler material may be paper, recycled paper, paperboard, fibreboard, cardboard, wood chips, plastic, recycled material, etc., but is not limited hereto. The filler material may have many different configurations such as, but not limited to, granulate, chips, sheets, layers, film, etc. 
         [0027]    The binding material may be some kind of glue, such as polyvinyl acetate glue, but not limited hereto, preferably chosen in accordance with other constructional parameters of the sanding device  1  as described below. 
         [0028]    A plurality of bristles  12  are arranged in the holes  21  and secured therein, preferably by staples and/or glue. The bristles  12  may be arranged in different patterns along the cylindrical core  10 , preferably in straight lines parallel to an axis of rotation  22  or in lines twisting around the cylindrical core  10  creating a spiral-like pattern. The axis of rotation  22  is defined as a line in space extending through the centre of the cylindrical core  10  in the longitudinal direction. The bristles  12  extend substantially radially from the surface  20  of the core  10 . 
         [0029]    Referring to  FIG. 1   a,  sections of abrasive cloth  11  are arranged between the bristles  12 . In the shown embodiment the abrasive cloth  11  is in the form of bent, elongated pieces of cloth secured to the surface of the core  10  by fastening means  13  such as, but not limited to, staples. Staples  13  are placed along a middle section of the abrasive cloth  11  in the longitudinal direction. The abrasive cloth  11  thus has a shape resembling a U with the staples placed in the bottom part. 
         [0030]    Referring to  FIG. 1   b  an embodiment of the inventions is shown where the abrasive cloth  11  is secured to the surface of the cylindrical core  10  by staples arranged along a longitudinal edges of the pieces of abrasive cloth  11 . In a still further embodiment as shown in  FIG. 1   c,  two pieces of abrasive cloth  11  are secured to the surface of the cylindrical core  10  by staples arranged in an overlapping section between the two pieces of abrasive cloth  11 . By utilizing two separate pieces of abrasive cloth  11 , it is possible to have a sanding device  1  with abrasive cloth having different grit sizes. Hereby the sanding device has one grit size when it is rotated in one direction and another grit size when it is rotated in the opposite direction. The abrasive cloth  11  extends substantially radially from the surface of the cylindrical core  10  and may be in abutment with the bristles. 
         [0031]    When securing the abrasive cloth by using staples  13 , it may be advantageous to use a reinforcement strip, e.g. a piece of cardboard, arranged on top of the pieces of abrasive cloth in the region where the staples are applied. By inserting the staples through both the reinforcement strip and the abrasive cloth, the tear resistance of the construction is improved. 
         [0032]    In an alternative embodiment, the pieces of abrasive cloth  11  may be secured to the surface for the core  10  using some kind of Velcro. By having mating pieces of Velcro on the pieces of abrasive cloth  11  and the core  10 , respectively, the abrasive cloth  11  may be removably secured to the core  10 . 
         [0033]    The cylindrical core described above may be used in many different types of sanding devices. Abrasive cloth and/or bristles may alternatively be secured in grooves in the core  10 . By utilizing grooves the abrasive cloth and/or bristles may be arranged in fastening strips adapted to be inserted in the grooves. A fastening strip may comprise several bristles  12  or pieces of abrasive cloth  11  arranged side by side. Fastening strips are widely used in known sanding devices. 
         [0034]    The binder used in the core material and the staples and/or glue used for securing the abrasive cloth  11  to the core  10  may be chosen in accordance with each other. It is desirable that the hardness and consistency of the core material are suitable for the utilized fastening means. 
         [0035]      FIG. 5  shows end pieces  30  for the sanding device  1 . Different types of end pieces  30  can be mounted on the sanding device  1 . The end pieces  30  can be standard end pieces or custom made according to the specific use. The end pieces  30  may preferably have a hole diameter ranging from 5 mm to 80 mm. In the shown embodiment, the end pieces  30  have hexagonal-shaped holes  31 . The sanding device  1  may be mounted in a sanding apparatus by inserting a shaft (not shown) through the hexagonal-shaped holes  31  in each of the end pieces  31 . In an alternative embodiment, the sanding device  1  may be mounted by only inserting a shaft through a hole  31  in one of the end pieces  30 . 
         [0036]    In an alternative embodiment as shown in  FIG. 6 , the cylindrical core  10  is substituted with a disc-shaped core  10   b  having a top surface  20   b  with a plurality of holes. In this embodiment, the plurality of bristles  12  and the pieces of abrasive cloth  11  extend in a direction perpendicular to the top surface  20   b  of the disc  10   b.  This direction corresponds to the direction of the axis of rotation of the disc. The bristles  12  and the pieces of abrasive cloth  11  are secured to the disc-shaped core  10   b  with means similar to the means used for securing bristles and the pieces of abrasive cloth to the cylindrical core. The disc-shaped core may have a shaft  20  extending from the centre of the disc and from a side opposite the top surface. The shaft thus extends in a direction opposite to the bristles and the pieces of abrasive cloth and parallel to the axis of rotation. Alternatively the shaft may be arranged excentrically and the disc core may be weighted to the effect that the abrasive paper entails an excentric movement. 
         [0037]    The base plate may be manufactured from a material comprising a filler and a binding material. The filler may be paper, recycled paper, paperboard, fibreboard, cardboard, wood chips, plastic, recycled material, etc., but is not limited hereto. The binding material may be some kind of glue, such as polyvinyl acetate glue, but is not limited hereto. 
         [0038]    The embodiment comprising as disc-shaped core may be used in both a commercial sanding apparatus and in connection with power tools, such as but not limited to a hand-held drilling machine. The sanding device may be mounted on a drilling machine by connecting the shaft  20  of the sanding device with the drill chuck or other means for securing equipment to a drilling machine. 
       Use of the Invention 
       [0039]    Having described the sanding device in detail, its use and operation will be described in further detail below. 
         [0040]    A sanding device  1  according to the invention is mounted in a sanding apparatus as described above. When the shaft is rotated, the sanding device  1  rotates accordingly. Depending on the specific embodiment, the sanding device may be rotated either clockwise, counter-clockwise or a combination of the two. Thus, when the abrasive cloth  11  has been worn sufficiently on one side, the rotation may be reversed to utilize the opposite side of the abrasive cloth  11 . When the abrasive cloth  11  has been worn sufficiently, either the entire sanding device  1  or only the abrasive cloth  11  may be replaced. The abrasive cloth  11  may be replaced by removal of the used abrasive cloth  11  and securing of new pieces of abrasive cloth to the sanding device  1 . This may be done by stapling of new pieces of abrasive cloth to the surface of the cylindrical core  10  or by securing of pieces of abrasive cloth to the sanding device  1  according to any one of the above mentioned embodiments.