Patent Publication Number: US-9889549-B2

Title: Precision handle for hand tools

Description:
FIELD 
     The present invention relates to an apparatus for hand tools, and more particularly to a precision handle for hand tools that can facilitate smooth and efficient operation of the hand tools. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     With reference to  FIG. 7 , when a hand tool is used in a precision environment, a conventional precision handle is mounted on a holding end of the hand tool to form a precision hand tool to prevent the hand tool from oscillating in use. The precision hand tool can remain steady and lineal during operation. So the precision hand tool is applied to the tiny screws of glasses, mobile phones or computers. The conventional precision handle comprises a body  80  and a positioning element  90 . The body  80  is a rod and has a front end, a rear end, a mounting protrusion  81 , and a tool head  82 . The mounting protrusion  81  is formed axially on and protrudes from the rear end of the body  80 . The positioning element  90  is a circular cap and is mounted around the mounting protrusion  81 . The tool head  82  is assembled at the front end of the body  80  when the hand tool is operated. In use, the tool head  82  is inserted into a screw, one hand of the user holds the positioning element  90 , and the other hand rotates the body  80 . The tool head  82  would rotate when the body  80  rotates, so as to fasten or loosen the screw. 
     However, the positioning element  90  is mounted around the mounting protrusion  81  directly, and the mounting protrusion  81  engages the positioning element  90  in a surface-to-surface contact. Thus the friction between the mounting protrusion  81  and the positioning element  90  increases when the body  80  rotates, and makes users unable to operate the precision hand tool smoothly. 
     To overcome the shortcomings of the conventional precision handle for hand tools, the present invention provides a precision handle for hand tools to mitigate or obviate the aforementioned problems. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     An aspect of the present invention is to provide a precision handle which could be operated smoothly and efficiently. 
     The precision handle for hand tools has a body, an elastic element, a sheath, a pressing element, and a group of balls. A mounting protrusion protrudes axially from a rear end of the body. The elastic element is mounted in the body. The sheath is mounted around the mounting protrusion. The pressing element is mounted through and engages with the sheath. The group of balls includes a first ball and a second ball. The first ball is mounted in the mounting protrusion and abuts the elastic element. The second ball is mounted between the pressing element and the first ball. The first ball abuts the second ball at one point of contact when the pressing element is pressed, which can decrease the friction between the body and the sheath. So the precision handle for hand tools may be operated smoothly and efficiently. 
     Other aspects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of a selected embodiment and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a perspective view of a precision handle for hand tools in accordance with an exemplary embodiment of the present invention; 
         FIG. 2  is an enlarged perspective view in partial section of the precision handle in  FIG. 1 ; 
         FIG. 3  is an exploded perspective view in partial section of the precision handle in  FIG. 1 ; 
         FIG. 4  is an enlarged and cross sectional side view of the precision handle in  FIG. 1 ; 
         FIG. 5  is an operational perspective view of the precision handle in  FIG. 1 ; 
         FIG. 6  is an operational enlarged side view of the precision handle in  FIG. 1 ; and 
         FIG. 7  is an exploded side view of a precision handle for a hand tool in accordance with the prior art. 
     
    
    
     DETAILED DESCRIPTION 
     An example embodiment will now be described more fully with reference to the accompanying drawings. 
     With reference to  FIGS. 1 to 3 , a precision handle for hand tools in accordance with an exemplary embodiment of the present invention comprises a body  10 , an elastic element  20 , a sheath  30 , a pressing element  40 , and a group of balls  50 . 
     The body  10  is rod-shaped and has a front end  101 , a rear end  102 , and a mounting protrusion  11 . A tool head may be mounted in the front end  101  of the body  10 . The mounting protrusion  11  is axially formed on and protrudes from the rear end  102  of the body  10  and comprises a rear side, a mounting recess  111 , a through hole  112 , and a limiting circular rib  113 . The rear side of the mounting protrusion  11  is opposite to the rear end  102  of the body  10  and has an inner diameter. The mounting recess  111  is formed in the mounting protrusion  11  adjacent to the rear end  102  of the body  10 . The through hole  112  is formed through the rear side of the mounting protrusion  11  and has an inner diameter. The inner diameter of the through hole  112  is larger than an inner diameter of the mounting recess  111 . The limiting circular rib  113  is formed in the mounting protrusion  11  at a connecting portion between the mounting recess  111  and the through hole  112 . The limiting circular rib  113  is tapered from the through hole  112  toward the mounting recess  111 . 
     The elastic element  20  is mounted in the mounting recess  111  via the through hole  112 . Preferably, the elastic element  20  is a spring. 
     The sheath  30  may be a tapered tube, is securely mounted around the mounting protrusion  11  of the body  10 , and comprises an inner surface, a proximal end  301 , a distal end  302 , a positioning circular rib  31 , and a connecting hole  32 . The proximal end  301  of the sheath  30  abuts the rear end  102  of the body  10 . The distal end  302  of the sheath  30  is opposite to the proximal end  301 . The positioning circular rib  31  is formed radially inward on the inner surface of the sheath  30  adjacent the distal end  302  of the sheath  30 . The connecting hole  32  is formed through the distal end  302  of the sheath  30  and communicates with the through hole  112 . 
     With reference to  FIG. 4 , the pressing element  40  is mounted through and engages with the sheath  30  and comprises a pressing disk  41  and an embedded portion  42 . The pressing disk  41  has a proximal face  410  and a distal face. The proximal face  410  faces the distal end  302  of the sheath  30 . The embedded portion  42  is formed axially on and protrudes from the proximal face  410  of the pressing disk  41  toward the mounting protrusion  11  and is mounted around the rear side of the mounting protrusion  11  via the connecting hole  32 . 
     The embedded portion  42  has an outer surface, a proximal side  420 , an engaging circular rib  421 , two constricting recesses  422 , and an embedding recess  423 . The proximal side  420  is opposite to the proximal face  410  of the pressing element  40 . The engaging circular rib  421  is formed radially outward on the embedded portion  42  at the proximal side  420  of the embedded portion  42 . The engaging circular rib  421  engages the positioning circular rib  31  of the sheath  30 , and this enables the pressing element  40  to be connected to the sheath  30  without separating. The two constricting recesses  422  are formed through the outer surface of the embedded portion  42  and the engaging circular rib  421  radially, thereby making the embedded portion  42  deformable. The two constricting recesses  422  face to each other. The embedding recess  423  is formed in the proximal side  420  of the embedded portion  42  axially and is a circular recess. The embedding recess  423  communicates with the two constricting recesses  422 . 
     The group of balls  50  is mounted in the sheath  30  between the mounting protrusion  11  of the body  10  and the pressing element  40 . The group of balls  50  comprises a first ball  51  and a second ball  52 . The first ball  51  is mounted in the mounting protrusion  11  via the through hole  112  and has a front side. A diameter of the first ball  51  is smaller than the inner diameter of the through hole  112 , while the diameter of the first ball  51  is larger than the inner diameter of the mounting recess  111 . The first ball  51  is located in the through hole  112 , and the front side of the first ball  51  extends in the mounting recess  111  to enable the first ball  51  to abut the elastic element  20 . The second ball  52  is embedded in the embedding recess  423  of the pressing element  40  and abuts the first ball  51  at one point of contact due to the pushing force between the elastic element  20  and the first ball  51 . An annular gap is formed between the distal end  302  of the sheath  30  and the pressing disk  41  of the pressing element  40 . 
     In use, with reference to  FIG. 5  and  FIG. 6 , a tool head  60  is assembled at the front end  101  of the body  10 , and then the tool head  60  is inserted into a screw. One hand of a user presses the pressing element  40 , making the pressing element  40  move toward the screw. While the pressing element  40  approaches the screw, the second ball  52  pushes the first ball  51 . The front side of the first ball  51  extends to the mounting recess  111  more deeply and abuts the limiting circular rib  113 , and then the first ball  51  compresses the elastic element  20 . During the operating process, the first ball  51  continually contacts the second ball  52  at one point of contact. At the same time, the engaging circular rib  421  is separated from the positioning circular rib  31  when the pressing element  40  is pushed to move relative to the sheath  30 . The other hand of the user holds the body  10 , and rotates the body  10  with the tool head  60  in a clockwise or a counter-clockwise direction, thereby fastening or loosening the screw. The screw, the body  10  and the pressing element  40  may remain precisely aligned linearly while the body  10  is rotating, which ensures the tool head  60  is operated precisely. Because the first ball  51  continually touches the second ball  52  at one point of contact while the body  10  is rotating, the friction between the body  10  and the pressing element  40  is decreased. 
     Compared with the conventional precision handle, wherein the mounting protrusion  81  engages the positioning element  90  in a surface-to-surface contact, the friction between the mounting protrusion  81  and the positioning element  90  is increased, and users are unable to operate the precision hand tool smoothly. The precision handle for hand tools of the present invention has the following advantages. 
     1. The first ball  51  continually touches the second ball  52  at one point of contact, which may decrease the friction between the body  10  and the pressing element  40 . Thus the precision handle can be operated more smoothly and more efficiently. 
     2. The screw, the body  10  and the pressing element  40  may stay precisely aligned and linear while the precision handle is operated. Thus the precision handle may maintain its precision since the friction between the body  10  and the pressing element  40  decreases. 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.