Patent Publication Number: US-2009235788-A1

Title: Hand tool for providing high twisting forces and low damage to screw

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation-in-part Application of Ser. No. 11/036,704, filed Jan. 18, 2005, and entitled “CLAMPING DEVICE FOR PROVIDING HIGH TWISTING FORCES AND LOW DAMAGE TO SCREW DEVICE”, now pending. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a hand tool, and more particularly to a hand tool for providing high twisting forces and low damage to a screw. 
     2. Description of Related Art 
     There are many improvements for improving the twisting force of a sleeve or a spanner. A conventional sleeve comprises a polygonal space defined therein. Each side of the polygonal space is teethed to increase the friction force between the sleeve and the screw received in the polygonal space. When a great twisting force is applied, the teeth are damaged at the apexes such that the friction force is reduced. The teeth also damage the screw. After a period of usage, the sleeve and the screw are broken. The conventional spanner with the teeth has the same problem. 
     The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional hand tool. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide an improved hand tool for providing high twisting forces and low damage to a screw. 
     To achieve the objective, the hand tool for providing high twisting forces and low damage to a screw includes a handle having a driving end formed in one end thereof. The driving end has an inner hexagonal space defined therein. The driving end has three engaging portions and three flat portions respectively form in six edges of the inner hexagonal space. The three engaging portions and the three flat portions are alternatively disposed. The driving end has six recesses formed therein. Each recess is disposed between each engaging portion and the flat portion adjacent to the engaging portion for receiving an apex of the screw. Each engaging portion has two cambered protrusions respectively extend from two ends thereof and a sharp protrusion extended therefrom and disposed between the two cambered protrusions. An apex of the sharp protrusion and those of the two cambered protrusions are collinear. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention; 
         FIG. 2  is a top plane view of the hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention, showing the driving end; 
         FIG. 3  is a top plane view of the hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention, showing the screw received in the inner hexagonal space; and 
         FIG. 4  is a perspective view of a second embodiment of a hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to  FIGS. 1-3 , a hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention is illustrated. In the preferred embodiment the hand tool is a spanner  10 . The hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention comprises a handle  11  having a driving end  12  formed in one end thereof. The driving end  12  has an inner hexagonal space  121  defined therein for receiving a screw  30 . The driving end  12  has three engaging portions  20  and three flat portions  21  respectively formed in six edges of the inner hexagonal space  121 . The three engaging portions  20  and the three flat portions  21  are alternatively arranged. The driving end  12  has six recesses  22  formed therein, each recess  22  disposed between the engaging portion  20  and the flat portion  21  for receiving an apex  31  of the screw  30  to prevent the screw  30  from damage. 
     Each engaging portion  20  has two cambered protrusions  201  extended therefrom and respectively disposed in two ends thereof. Each engaging portion  20  has a sharp protrusion  202  extended therefrom and disposed between the two cambered protrusions  201 . An apex of the sharp protrusion  202  and those of the two cambered protrusions  201  are collinear. 
     Referring to  FIG. 3 , the hexagonal screw  30  is received in the inner hexagonal space  121 . Each flat portion  21  abuts against a flat surface  32  of the screw  30  for providing more contacting surface. The two cambered protrusions  201  and the sharp protrusion  202  of each engaging portion  20  abuts against the other one flat surface  32  of the screw  30  for increasing a twisting force from the spanner  10  to the screw  30 . Each apex  31  of the screw  30  is received in the recess  22  such that the apex  31  will not wear. The flat portion  21 , the cambered protrusion  201 , and the sharp protrusion  202  increase the friction force such that the screw  30  is driven easily. 
     Referring to  FIG. 4 , a second embodiment of the hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention is illustrated. In the second embodiment, the hand tool is a sleeve  40 . The hand tool for providing high twisting forces and low damage to a screw in accordance with the present invention comprising a sleeve  40  having an inner hexagonal space  121  defined therein. The sleeve  40  has three engaging portions  20  and three flat portions  21  respectively formed in six edges of the inner hexagonal space  121 . The three engaging portions  20  and the three flat portions  21  are alternatively arranged. The sleeve  40  has six recesses  22  formed therein, each recess  22  disposed between the engaging portion  20  and the flat portion  21 . 
     Each engaging portion  20  has two cambered protrusions  201  extended therefrom and respectively disposed in two ends thereof. Each engaging portion  20  has a sharp protrusion  202  extended therefrom and disposed between the two cambered protrusions  201 . A apex of the sharp protrusion  202  and those of the two cambered protrusions  201  are collinear. 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.