Patent Publication Number: US-6905401-B1

Title: Bi-directional rotation pneumatic grinding tool

Description:
FIELD OF THE INVENTION 
   The present invention relates to a pneumatic grinding tool and particularly to a bi-directional rotation pneumatic grinding tool. 
   BACKGROUND OF THE INVENTION 
   There are many types of grinding machines. They mostly are designed for uni-rotation at low speed and high torque to treat rough surfaces. Depending on the surface to be treated, the grinding operation can be divided in plane grinding and side grinding. Because the grinding tools are designed in a versatile fashion, they are widely used in various industries such as iron works, machinery, wood working, mold fabrication, car and motorcycle repair shops, fiberglass, electronics and the like. By changing the grinding member of different granular sizes, they can perform many different functions such as polishing, rust removing, glue removing, grinding, wax polishing, rough edge trimming, drilling, etc. 
   As to the actuating section used in the conventional. uni-direction, low speed and high torque grinding machines, refer to  FIG. 1  for an actuating section  1  for a conventional pneumatic grinding machine. It has a transmission axle  13  extended outwards from the actuating section  1 . A bearing  14  is coupled on the transmission axle  13 . The transmission axle  13  further is fastened to a coupling member  10  by screwing. The coupling member  10  has a through fastening hole  15 . The coupling member  10  is fastened to a fastening member  11 . When in use, a grinding member  12  is clamped and anchored between the coupling member  10  and the fastening member  11 , and is driven by the transmission axle  13  to rotate at high speed in one direction. However, when in operation, the uni-rotation grinding machine set forth above generally will generate a lot sparks, grinding debris, powders or dusts. The sparks are scattered around and may cause fire when inflammable goods are held nearby. The dusts create pollution in the operation environment. The scattered debris seriously affects the health and safety of operators. As the conventional grinding machines rotate in one direction, when to process a narrow work piece or a comer, the handgrip design of the conventional grinding machine could make operation difficult and result in a portion of the surface or corners of the work piece not possible to be treated as desired. Operators have to change their operating postures. This could affect the grinding quality and produce detects. Moreover, when the grinding member  12  rotates at high speed, a greater torque often occurs to the exposed portion of the transmission axle  13 . The transmission axle  13  receives uneven distribution of torque and might deform or even damage. All these inconveniences and problems reduce the product effectiveness and undercut marketing competitiveness. 
   SUMMARY OF THE INVENTION 
   The primary object of the invention is to solve the aforesaid disadvantages. The present invention provides a novel design for transmission axle which can rotate in a positive direction or an inverse direction so that the sparks, grinding debris, or dusts generated during grinding operation may be directed in a desired direction to avoid creating pollution in the working environment or harmful effects to operators and work pieces. 
   Another object of the invention is to provide a transmission axle with a spline section that may be fabricated easily without concerning the screwing direction occurred to the conventional structure. 
   Yet another object of the invention is to allow the torque to be evenly applied on the fastening member to prevent deformation or damage thereof resulting from uneven torque distribution. 
   The bi-directional rotation pneumatic grinding tool according to the invention includes an operating section and a handgrip. The operating section includes: 
   an actuator to drive a transmission axle to rotate in two directions. The transmission axle has a spline section and a screw hole formed on the spline section; 
   a coupling member which has through openings on two ends. One end has a coupling section with a first splined trough formed therein to couple with the spline section of the transmission axle; 
   a fastening member which has through openings on two ends. One end has a second splined trough formed on an inner wall and may be inserted into the coupling member to couple with the spline section of the transmission axle; and 
   a fastening element which has screw threads and runs through the fastening member to be fastened to the screw hole of the transmission axle. 
   Because the transmission axle is designed with the spline section, the problems occurred to the conventional techniques may be overcome. 
   The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a fragmentary sectional view of the operating section of a conventional pneumatic grinding tool. 
       FIG. 2  is a perspective view of the present invention. 
       FIG. 3  is an exploded view of the present invention. 
       FIG. 4  is a fragmentary sectional view of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Please referring to  FIGS. 2 ,  3  and  4 , the bidirectional rotation pneumatic grinding tool according to present invention is adopted for use on surface treatment. It includes a grinding member  4 , an operating section  3  and a handgrip  2 . The operating section  3  includes: 
   an actuator  34  to drive a transmission axle  30  to rotate in two directions; the transmission axle  30  having a spline section  300  and a screw hole  301  formed in the spline section; 
   a coupling member  31  which has through openings on two ends; one end having a stepwise coupling section  310  with a first splined trough  311  formed therein to couple with the spline section  300  of the transmission axle  30 ; 
   a fastening member  32  which has through openings on two ends; one end having a second splined trough  320  formed on an inner wall and being insertable into the coupling member is  31  to couple with the spline section  300  of the transmission axle  30 ; and 
   a fastening element  33  which has a compression section  331  on one end with screw threads  330  formed thereon to run through the fastening member  32  to fasten to the screw hole  301  of the transmission axle  30 . 
   By means of the construction set forth above, the spline section  300  and the first and second splined troughs  311 , 320  may be coupled to enable the invention to rotate in the positive or inverse direction to meet different requirements without loosening off. The spline structure may be fabricated simply and assembled easily without concerning the direction of screwing occurred to the conventional techniques. And the sparks, grinding debris or dusts generated during grinding operation may be directed in a desired direction without polluting the working environment or hurting people or damaging the equipment. 
   While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.