Abstract:
The present invention relates to a disc for abrading which is fitted to an electrically driven tool and is able to freely abrade flat surfaces and curved surfaces. And provided is a disc for abrading flat surfaces and curved surfaces, wherein the disc comprises: a holder of a plastic material, which rotates following the coupling of the electrically driven tool into a coupling hole formed in the centre thereof; a disc-shaped abrasive-fabric assembly formed by stacking layers of a plurality of abrasive-fabric pieces circumferentially along the edge of the holder; a resin layer for integrally linking the holder and the abrasive-fabric assembly; and a circular curving part which is formed between the edge of the holder and the edge of the abrasive-fabric assembly, and wherein the curving part can flex along the surface of a material to be abraded, so as to freely abrade a flat surface or curved surface of the material to be abraded.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a National phase of PCT patent Application No. PCT/KR2013/000835 having an International filing date of Feb. 1, 2013, which claims priority to Korean Patent Application No. 20-2012-0001214, filed on Feb. 16, 2012, the entireties of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The embodiment relates to a disc which is mounted on an electrically driven tool and freely abrades a flat or curved surface, and more particularly to a plastic-made holder with a reduced diameter is disposed on the back side of an abrasive-fabric assembly formed by circumferentially overlapping a plurality of abrasive-fabric pieces and is integrally fixed to the abrasive-fabric assembly by a resin layer, so that the abrasive-fabric assembly can easily flex along the surface of a material to be abraded, thereby conveniently abrading the flat or curved surface and extending the available abrasive surface to the central portion of the abrasive fabric. The disc for abrading the flat or curved surface is environmentally-friendly because the whole amount of the used disc is incinerated. 
       BACKGROUND OF THE INVENTION  
       [0003]    In general, the surface of a metal material used in manufacturing machines or other products has a roughness greater than a certain particle size. In a machining process such as cutting, welding or the like, the surface of the metal material often becomes rough. 
         [0004]    An abrading operation is performed on the metal surface so as to smooth the rough surface of the metal material or to remove the processed bit of the surface. 
         [0005]    Here, an abrading device which abrades the metal surface includes an abrasive disc which is coupled to the electrically driven tool and abrades the metal surface by rotation. The conventional abrasive disc  1  generally includes, as shown in  FIG. 1 , a disc-shaped abrasive-fabric assembly  10  and a back pad  20 . The disc-shaped abrasive-fabric assembly  10  is formed by circumferentially overlapping and stacking a plurality of abrasive-fabric pieces  10   a  such that an insertion hole is formed in the central portion thereof. The back pad  20  has a certain diameter, is inserted and fixed to the insertion hole of the abrasive-fabric assembly  10 , and has a coupling hole  22  formed in the center thereof to which the electrically driven tool is inserted and coupled. 
         [0006]    In the conventional abrasive disc  1 , the diameter of the back pad  20  is almost the same as that of the abrasive-fabric assembly  10 , so that the abrasive-fabric assembly  10  is stably supported without being bent while performing the abrading operation. 
         [0007]    The above-structured conventional abrasive disc  1  rotates while in contact with the surface to be abraded of the metal material such that the surface of the material to be abraded is easily abraded. 
         [0008]    Generally, the metal surface to be abraded is formed to be flat or curved. When the flat metal surface is abraded, the diameter of the back pad  20  is, as shown in  FIG. 2   a , almost the same as that of the abrasive-fabric assembly  10 . Therefore, the abrasive-fabric assembly  10  is not bent during the abrading operation and performs well the abrading operation with being stably supported on the surface of the material  30  to be abraded. 
         [0009]    However, as shown in  FIG. 2   b , in abrading a recessed portion or a corner  40 , since the back pad  20  has a plate structure which is not bent, the abrading operation is difficult to perform appropriately. 
         [0010]    Also, as shown in  FIG. 2   c , when a surface to be abraded is a concave surface  50 , it is difficult to perform the abrading operation. Therefore, in this case, it is troublesome to select the disc for abrading the flat surface or the disc for abrading the curved surface in accordance with the metal surface to be abraded. 
         [0011]    In the conventional abrasive disc  1 , an available portion of the abrasive-fabric assembly  10  which is worn away during the abrading operation is limited to an outer edge of the back pad  20 . Therefore, since the available portion of the abrasive-fabric assembly  10  is worn away by being used even for a short period of time, the abrasive-fabric assembly  10  has a short lifespan. 
         [0012]    Also, in the conventional abrasive disc  1 , when the available portion of the abrasive-fabric assembly  10  is worn away, the back pad  20  contacts frequently with the surface of the material  30  to be abraded, so that excessive friction occurs. As a result, a burning mark is often generated in the material  30  to be abraded. 
         [0013]    The back pad  20  provided in the conventional abrasive disc  1  is often formed by applying and stacking an adhesive resin, etc., on a plurality of meshes made of glass fiber and then by hardening it with rapidity. The back pad  20  is a disc-shaped member which has a low elasticity and high fragility. 
         [0014]    Accordingly, the conventional back pad  20  is made of glass fiber which is harmful to industrial safety due to the nature of the material. The used glass fiber is not treated in an environmentally friendly manner, e.g., incineration, etc. As a result, there is a problem that industrial wastes are generated. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS  
         [0015]      FIG. 1  is a perspective view showing an appearance of a back pad abrasive disc according to a conventional technology; 
           [0016]      FIG. 2   a  is a view for describing that the back pad abrasive disc according to the conventional technology abrades a flat material to be abraded; 
           [0017]      FIG. 2   b  is a view showing that the back pad abrasive disc according to the conventional technology has a difficulty in abrading a recessed portion or corner of the material to be abraded; 
           [0018]      FIG. 2   c  is a view showing that the back pad abrasive disc according to the conventional technology has a difficulty in abrading a curved portion the material to be abraded; 
           [0019]      FIG. 3  is a perspective view showing an appearance of a disc for abrading a flat or curved surface in accordance with an embodiment of the present invention; 
           [0020]      FIG. 4  is an enlarged cross sectional view showing a space for mounting a resin layer of a holder provided in the disc for abrading the flat or curved surface in accordance with the embodiment of the present invention; 
           [0021]      FIG. 5  is a partial cut cross sectional view of the disc for abrading the flat or curved surface in accordance with the embodiment of the present invention; 
           [0022]      FIG. 6   a  is a view for describing that the disc for abrading the flat or curved surface in accordance with the embodiment of the present invention abrades a flat material to be abraded; 
           [0023]      FIG. 6   b  is a view for describing that the disc for abrading the flat or curved surface in accordance with the embodiment of the present invention easily abrades the recessed portion or corner of the material to be abraded; and 
           [0024]      FIG. 6   c  is a view for describing that the disc for abrading the flat or curved surface in accordance with the embodiment of the present invention abrades the curved portion of the material to be abraded. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Technical Assignment  
       [0025]    The embodiment of the present invention is provided to solve the problems. An objective of present invention is to provide an improved disc which is capable of conveniently and effectively abrading the flat and curved surface of the material to be abraded, of extending the available abrasive surface to the central portion of the abrasive fabric, and thus greatly extending the lifespan of the abrasive fabric, and of preventing the burning mark from being generated in the surface of the material to be abraded. 
         [0026]    Another objective of the embodiment of the present invention is to provide an improved disc which is capable of abrading the flat and curved surface without generating glass fiber powder, etc., harmful to a user, and of allowing the user to safely use the disc in an environmentally friendly manner by incinerating the whole amount of the used disc. 
       Technical Solution  
       [0027]    To accomplish the objectives, an embodiment of the present invention is to provide a disc which is mounted on an electrically driven tool and abrades a surface of a material to be abraded. 
         [0028]    The disc includes: a plastic-made holder which has a coupling hole formed in a central portion thereof and rotates by coupling an electrically driven tool to the coupling hole, a disc-shaped abrasive-fabric assembly formed by circumferentially overlapping and stacking a plurality of abrasive-fabric pieces along an edge of the holder, a resin layer which integrally links the holder and the abrasive-fabric assembly, and a circular curving part formed between an edge of the holder and an edge of the abrasive-fabric assembly. The curving part flexes along the surface of the material to be abraded and freely abrades a flat surface or curved surface of the material to be abraded. 
         [0029]    According to the embodiment of the present invention, preferably, the diameter of the holder is ⅓ to ⅔ of the outer diameter of the abrasive-fabric assembly. The curving part forms an available abrasive surface having a size from the outside of the edge of the holder to ⅓ to ⅔ of the outer diameter of the abrasive-fabric assembly. 
         [0030]    According to the embodiment of the present invention, preferably, a concave groove is formed on one side of the circumference of the coupling hole of the holder. A catching stepped portion is formed on an outer edge of the concave groove. A ring groove is formed concave on an inner edge opposite to the catching stepped portion, so that a mounting space in which the resin layer fixes an inner edge of the abrasive-fabric assembly to the holder is formed to extend. 
         [0031]    According to the embodiment of the present invention, preferably, the resin layer extends from the mounting space of the holder to the edge of the holder and the mid-point of the edge of the abrasive-fabric assembly, and elastically supports a back side of the curving part. 
       Advantageous Effects  
       [0032]    In the disc for abrading the flat and curved surface in accordance with the embodiment of the present invention, a circular curving part is formed between the edge of the holder and the edge of the abrasive-fabric assembly and flexes along the surface of the material to be abraded, so as to freely abrade the flat surface or curved surface of the material to be abraded. The diameter of the holder is ⅓ to ⅔ of the outer diameter of the abrasive-fabric assembly. The curving part forms an available abrasive surface having a size from the outside of the edge of the holder to ⅓ to ⅔ of the outer diameter of the abrasive-fabric assembly. 
         [0033]    Accordingly, according to the embodiment of the present invention, through use of the curving part, it is possible to conveniently and effectively abrade the flat and curved surface of the material to be abraded, to extend the available abrasive surface to the central portion of the abrasive fabric, thereby greatly extending the lifespan of the abrasive fabric, and to prevent the burning mark from being generated in the surface of the material to be abraded. 
         [0034]    Also, according to the embodiment of the present invention, the disc-shaped holder made of plastic mold is used instead of the existing back pad made of glass fiber, and a resin layer integrally links the abrasive-fabric assembly and the holder. Therefore, glass fiber powder, etc., harmful to a user is not generated during the abrading operation, and the user is allowed to safely use the disc in an environmentally friendly manner by incinerating the whole amount of the used disc. 
       MODE FOR INVENTION  
       [0035]    Hereafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
         [0036]    A disc  100  for abrading a flat or curved surface in accordance with an embodiment of the present invention is mounted on an electrically driven tool  105  and abrades the surface of a material to be abraded. As shown in  FIG. 3 , the disc  100  for abrading the flat or curved surface includes a plastic-made holder  110  which has a coupling hole  112  formed in the central portion thereof. The electrically driven tool  105  is coupled to the coupling hole  112 , and then the holder  110  rotates. 
         [0037]    The embodiment of the present invention includes a disc-shaped abrasive-fabric assembly  120  formed by circumferentially overlapping and stacking a plurality of abrasive-fabric pieces  120   a  along an edge  110   a  of the holder  110 , and includes a resin layer  130  which integrally links the holder  110  and the abrasive-fabric assembly  120 . 
         [0038]    The embodiment of the present invention includes a circular curving part  150  formed between the edge  110   a  of the holder  110  and an edge  122   a  of the abrasive-fabric assembly  120 . 
         [0039]    The holder  110  provided in the disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention is plastic-molded in the form of a disc. Instead of the conventional back pad  20  made of glass fiber, the holder  110  is mounted on the electrically driven tool  105  through the central coupling hole  112 . 
         [0040]    In this case, when the electrically driven tool  105  is coupled to the coupling hole  112  of the holder  110 , a separate steel cap (not shown) or a plastic reinforcing cap (not shown) may be additionally used for the purpose of structural strength between the electrically driven tool  105  and the coupling hole  112 . 
         [0041]    The diameter of the holder  110  is ⅓ to ⅔ as large as the outer diameter D 2  of the abrasive-fabric assembly  120 . The diameter D 1  of the holder  110  is greatly reduced compared with that of the conventional back pad  20 . A portion of the abrasive-fabric assembly  120 , which is formed at the outside of the edge  110   a  of the holder  110  forms the circular curving part  150 . 
         [0042]    Therefore, the curving part  150  forms an available abrasive surface having a size from the outside of the edge  110   a  of the holder  110  to ⅓ to ⅔ of the outer diameter D 2  of the abrasive-fabric assembly  120 . 
         [0043]    Accordingly, since the curving part  150  can flex along a flat  182   a  or a curved surface  182   c  of a material  180  to be abraded, it can be conveniently applied to the flat  182   a  and the curved surface  182   c  respectively, so that the material  180  to be abraded can be effectively abraded. It is possible to extend the available abrasive surface to the central portion of the abrasive fabric assembly  120 , and thus to greatly extend the lifespan of the abrasive fabric assembly  120 . 
         [0044]    The disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention forms a mounting space  160  for coupling the disc-shaped abrasive-fabric assembly  120  to the holder  110 . As shown in the enlarged cross sectional view of  FIG. 4 , the mounting space  160  corresponds to an annular concave groove  162  formed on one side of the circumference of the coupling hole  112  of the holder  110 . 
         [0045]    The holder  110  has a structure in which a catching stepped portion  164  is formed on the outer edge of the concave groove  162  and a ring groove  166  is formed concave on the inner edge opposite to the catching stepped portion  164 . 
         [0046]    In the holder  110 , the resin layer  130  is applied in the mounting space  160 , so that an inner edge  122   b  of the abrasive-fabric assembly  120  is fixed to the holder  110 . The catching stepped portion  164  formed on the outer edge of the concave groove  162  causes, as shown in  FIG. 5 , the resin layer  130  to be caught by the concave groove  162  in the radial direction of the holder  110 , thereby causing the resin layer  130  to effectively resist the rotation centrifugal force applied to the abrasive-fabric assembly  120  during the high speed rotation of the abrading disc  100  and preventing the abrasive-fabric assembly  120  and the resin layer  130  from being separated from the holder  110 . 
         [0047]    In addition, the ring groove  166  formed in the inner edge of the concave groove  162  increases greatly the internal volume of the mounting space  160 , thereby increasing the attachment surface area between the resin layer  130  and the holder  110 . As a result, the resin layer  130  is more securely attached to the mounting space  160  of the holder  110 . 
         [0048]    The resin used in the embodiment of the present invention may include an epoxy resin or FRP which has an excellent mechanical property such as a bending strength, hardness or the like. 
         [0049]    Meanwhile, preferably, in the embodiment of the present invention, the resin layer  130  extends from the mounting space  160  of the holder  110  to the edge  110   a  of the holder  110  and the mid-point of the edge  122   a  of the abrasive-fabric assembly  120 , and elastically supports the back side of the curving part  150 . 
         [0050]    When the disc  100  for abrading according to the embodiment of the present invention abrades the curved surface  182   c  of the metal material, the size of the holder  110  supporting the abrasive-fabric assembly  120  is significantly less than that of the existing back pad  20 . Therefore, the extension structure of the curving part  150  effectively solves a problem that the abrasion efficiency is deteriorated due to the abrading operation without correctly supporting the abrasive-fabric assembly  120 . 
         [0051]    That is, the resin layer  130  extending to the curving part  150  elastically supports the back side of the abrasive-fabric assembly  120 , so that the abrasion efficiency is improved and the lifespan of the disc  100  for abrading according to the embodiment of the present invention can be remarkably extended by using the entire curving part  150  in the abrading operation. 
         [0052]    When the above-configured disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention abrades the material  180  to be abraded, the curving part  150  flexes along the surface of the material  180  to be abraded, and thus, the disc  100  is able to freely abrade the flat  182   a  or curved surface  182   c  of the material  180  to be abraded. 
         [0053]    In other words, as shown in  FIG. 6   a , the electrically driven tool  105  is inserted and fixed to the central coupling hole  112  of the holder  110  on which the abrasive-fabric assembly  120  has been mounted. Then, the disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention rotates by the rotation of the electrically driven tool  105 , and then abrades the surface of the material  180  to be abraded. 
         [0054]    Here, like the conventional abrasive disc, the disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention is easily able to abrades the flat  182   a  of the material  180  to be abraded 
         [0055]    Moreover, as shown in  FIG. 6   b , since the curving part  150  can flex along a recessed portion or a corner  182   b  of the material  180  to be abraded, the disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention is easily able to abrades the recessed portion or the corner  182   b  of the material  180  to be abraded. 
         [0056]    Also, as shown in  FIG. 6   c , since the curving part  150  can flex along the curved surface  182   c  of the material  180  to be abraded, the disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention is easily able to abrades the curved surface  182   c  of the material  180  to be abraded. 
         [0057]    In this case, as shown in  FIGS. 3 and 5 , the abrasive-fabric assembly  120  is bent within a certain range without being excessively bent by the resin layer  130  supporting the back side of the curving part  150 , and closely contacts with the surface of the material  180  to be abraded. 
         [0058]    Accordingly, even when the surface of the material  180  to be abraded is the flat  182   a,  the recessed portion, the corner  182   b  or the curved surface  182   c,  the abrasive-fabric assembly  120  of the embodiment of the present invention stably closely contacts with and effectively abrades the surface of the material  180  to be abraded. 
         [0059]    As such, in the disc  100  for abrading the flat or curved surface in accordance with the embodiment of the present invention, the circular curving part  150  is formed between the edge  110   a  of the holder  110  and the edge  122   a  of the abrasive-fabric assembly  120  and flexes along the surface of the material  180  to be abraded, so as to freely abrade the flat surface  182   a  or curved surface  182   c  of the material  180  to be abraded. The diameter D 1  of the holder  110  is ⅓ to ⅔ of the outer diameter D 2  of the abrasive-fabric assembly  120 . The curving part  150  forms the available abrasive surface having a size from the outside of the edge  110   a  of the holder  110  to ⅓ to ⅔ of the outer diameter D 2  of the abrasive-fabric assembly  120 . 
         [0060]    Accordingly, according to the embodiment of the present invention, through use of the curving part  150 , it is possible to conveniently and effectively abrade the flat  182   a  and curved surface  182   c  of the material  180  to be abraded, to extend the available abrasive surface to the central portion of the abrasive fabric assembly  120 , thereby greatly extending the lifespan of the abrasive fabric, and to prevent the burning mark from being generated in the surface of the material  180  to be abraded. 
         [0061]    Also, according to the embodiment of the present invention, the disc-shaped holder  110  made of plastic mold is used instead of the existing back pad  20  made of glass fiber, and the resin layer  130  integrally links the abrasive-fabric assembly  120  and the holder  110 . Therefore, glass fiber powder, etc., harmful to a user is not generated during the abrading operation, and the user is allowed to safely use the disc in an environmentally friendly manner by incinerating the whole amount of the used disc. 
         [0062]    Though the embodiment of the present invention has been described in detail with reference to the accompanying drawings, the present invention is not limited to the specific structure. Those skilled in the art is able to variously change or modify the present invention without departing from the spirit and scope of the present invention disclosed in the utility registered claims. However, it is intended to mention that all the design changes or modified structures will clearly belong to the scope of the present invention.