Patent Publication Number: US-2006005979-A1

Title: Wear-reducing structure for rotary shaft of pneumatic tool

Description:
BACKGROUND OF THE INVENTION  
      The present invention is related to a pneumatic tool, and more particularly to a wear-reducing structure for rotary shaft of a pneumatic tool.  
      U.S. Pat. No. 3,174,597 discloses a technique related to a pneumatic tool. In this technique, via a pin clutch, two pin rammers ram the anvils of a rotary shaft to drive the rotary shaft. Such driving technique has been widely used in the field of pneumatic tool. However, when the rotary shaft rotates, noise and wear due to friction between metals take pace to limit the effect of the pneumatic tool. More specifically, when the rotary shaft rotates at high speed, the friction between the rotary shaft and the bush will lead to wear of the rotary shaft and the bush. Also, the friction results in loss of output power. Moreover, due to the wear of the parts, abnormal gaps will exist between the parts to enlarge the noise produced in operation of the pneumatic tool. All the above problems are not improved or solved in the prior art.  
     SUMMARY OF THE INVENTION  
      It is therefore a primary object of the present invention to provide a wear-reducing structure for rotary shaft of a pneumatic tool, which can effectively reduce the wear of the rotary shaft and adjacent parts of the pneumatic tool when the rotary shaft rotates.  
      It is a further object of the present invention to provide the above wear-reducing structure for rotary shaft of the pneumatic tool, which can avoid unnecessary loss of power during transmission.  
      It is still a further object of the present invention to provide the above wear-reducing structure for rotary shaft of the pneumatic tool, which can reduce the noise produced when the rotary shaft rotates.  
      According to the above objects, the wear-reducing structure for rotary shaft of pneumatic tool of the present invention includes: a rotary shaft having a predetermined length; two anvil blocks with a predetermined shape, the anvil blocks projecting from a middle section of the rotary shaft; a collar section fitted on the rotary shaft and correspondingly adjacent to the anvil blocks; and a bearing section fitted around the rotary shaft between the anvil blocks and the collar section. The bearing section includes several rolling bodies for abutting against a corresponding portion of an end face of the collar section. When the rotary shaft is rotated relative to the collar section, the rolling bodies roll relative to the collar section to reduce resistance.  
      The present invention can be best understood through the following description and accompanying drawings wherein:  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective exploded view of a preferred embodiment of the present invention;  
       FIG. 2  is a perspective assembled view of the preferred embodiment of the present invention;  
       FIG. 3  is a perspective partially sectional view of the preferred embodiment of the present invention;  
       FIG. 4  is a cross-sectional view of the preferred embodiment of the present invention; and  
       FIG. 5  is a partially longitudinal sectional view of the preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Please refer to FIGS.  1  to  5 . The wear-reducing structure  10  for rotary shaft of pneumatic tool includes a rotary shaft  20 , two anvil blocks  30 , a collar section  40  and a bearing section  50 .  
      The rotary shaft  20  is a rod body with a predetermined length. One end of the rotary shaft  20  is formed with multiple ratchet ribs  21 . The other end of the rotary shaft  20  is formed with a quadrangular connector  22 . The outer diameter of the rotary shaft  20  is varied along the axis of the rotary shaft  20 . In fact, the rotary shaft  20  pertains to prior art. In other words, the rotary shaft  20  is a conventional component of a pneumatic tool.  
      The anvil blocks  30  back to back project from a middle section of the rotary shaft  20  at an angular interval of 180 degrees. The anvil blocks  30  are for a pin rammer  61  of a conventional ramming mechanism  60  to ram. The jaw-shaped anvil blocks  30  also pertain to prior art.  
      The collar section  40  is a tubular sleeve body with a certain length for fitting on one end of the rotary shaft  20 . The collar section  40  is adapted to connect with a housing of the pneumatic tool for supporting the rotary shaft  20 . In this embodiment, the collar section  40  is a tubular sleeve. However, in practical application, the collar section  40  is not limited to the sleeve. For example, alternatively, the collar section  40  can be a section of the housing of the pneumatic tool.  
      The bearing section  50  has an annular seat body  51  coaxially fitted on the rotary shaft  20  between the anvil blocks  30  and the collar section  40 . The annular seat body  51  has a certain thickness. An annular groove  52  with a certain depth is formed on one face of the seat body  51  facing one end of the collar section  40 . The annular groove  52  has an opening correspondingly opposite to the circumference of the end of the collar section  40 . Several ball-shaped rolling bodies  53  are accommodated in the annular groove  52 . The outer diameter of the rolling body  53  is slightly larger than the depth of the annular groove  52 . Therefore, the rolling bodies  53  partially protrude from the opening of the annular groove  52  to abut against the circumference of the end of the collar section  40 .  
      According to the above arrangement of the wear-reducing structure  10  for the rotary shaft of pneumatic tool, by means of the bearing section  50 , the relative movement between the rotary shaft  20  and the collar section  40  is changed from the conventional sliding contact state into a rolling contact state. When the rotary shaft  20  is driven by an external power to rotate relative to the collar section  40  at high speed, the resistance can be reduced through the point contact between the rolling bodies  53  and the collar section  40  by way of rolling movement. Therefore, the loss of power can be reduced. Under the same strength of external application force, the rotational speed of the rotary shaft  20  can be enhanced. In addition, through the above rolling movement, the wear caused by friction can be reduced to enhance the durability of the components and avoid noise.  
      The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.