Abstract:
A double-grinding-wheel type drill bit grinding device with a single driving shaft and grinding method thereof comprising a power source disposed on a table, two grinding wheels being disposed at both ends of a single power shaft extending out of the power source. The grinding device further comprises a first grinding seat with multi-axes deflectable cutting edges, and a second grinding seat with an apex and adjustable apex depth, so that the grinding device is capable of grinding right spin drill bit or left spin drill bit. The power source is a pneumatic motor and is provided with an absorbing passage for facilitating dust discharge, therefore, it is environmental friendly. The multi-axes deflectable first grinding seat and the second position-adjustable seat, the grinding seat is improved in terms of applicability and adjustability.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present invention is a continuation-in-part application of the co-pending U.S. application Ser. No. 11/405,413, filed on Apr. 18, 2006. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a double-grinding-wheel type drill bit grinding device with a single driving shaft and grinding method thereof, and more particularly to a grinding device with a grinding wheel at each end of the power shaft of the power source. With the two grinding wheels and their positioning devices, and two grinding seats between the two grinding wheels, the grinding device is capable of grinding right spin drill bit or left spin drill bit.  
         [0004]     2. Description of the Prior Art  
         [0005]     U.S. Pat. No. 38,119 discloses a drill bit structure, and U.S. Pat. No. 6,517,411 discloses a grinding device designed for grinding the drill bit structure of U.S. Pat. No. 38,119, the drill bit grinding device is provided with two grinding wheels at both sides of the table thereof. This type of drill bit grinding device is a large-scale machine, and the two grinding wheels are driven by two different power source, it is not only difficult to carry but also wastes energy source. Further, its adjustable range of the grinding angle is too limited since only the flat grinding surface of the grinding wheels cooperates with the base for fixing the drill bit, and it is unable to grind the right spin drill bit and the left spin drill bit simultaneously, and the grinding operation must depend on the individual grinding skills, otherwise, it will cause grinding errors.  
         [0006]     U.S. Pat. No. 6,652,367 discloses another drill bit grinding device which employs a single driving shaft to drive a single grinding wheel, and this type single driving shaft type grinding device is also unable to grind the right spin drill bit and the left spin drill bit simultaneously.  
         [0007]     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.  
       SUMMARY OF THE INVENTION  
       [0008]     The primary objective of the present invention is to provide a double-grinding-wheel type drill bit grinding device with a single driving shaft and grinding method thereof comprising a power source disposed on a table, two grinding wheels being disposed at both ends of a single power shaft extending out of the power source. The grinding device further comprises a first grinding seat with multi-axes deflectable cutting edges, and a second grinding seat with an apex and adjustable apex depth, so that the grinding device is capable of grinding right spin drill bit or left spin drill bit.  
         [0009]     The second objective of the present invention is to provide a double-grinding-wheel type drill bit grinding device with a single driving shaft and grinding method thereof, wherein the power source is a pneumatic motor and is provided with an absorbing passage for facilitating dust discharge, therefore, it is environmental friendly.  
         [0010]     Another objective of the present invention is to provide a double-grinding-wheel type drill bit grinding device with a single driving shaft and grinding method thereof, with the multi-axes deflectable first grinding seat and the second position-adjustable seat, the grinding seat of the present invention can be improved in terms of applicability and adjustability. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a perspective view of a double-grinding-wheel type drill bit grinding device with a single driving shaft in accordance with the present invention;  
         [0012]      FIG. 2  shows the interior of the double-grinding-wheel type drill bit grinding device with a single driving shaft in accordance with the present invention after the covers open;  
         [0013]      FIG. 3  is an exploded view of the double-grinding-wheel type drill bit grinding device with a single driving shaft in accordance with the present invention;  
         [0014]      FIG. 4  is an amplified view of a second grinding seat in accordance with the present invention;  
         [0015]      FIG. 5  is an amplified view of the positioning devices in accordance with the present invention;  
         [0016]      FIG. 6  is an assembly view of the double-grinding-wheel type drill bit grinding device with a single driving shaft in accordance with the present invention;  
         [0017]      FIG. 7-1  is a perspective view of a grinding wheel in accordance with the present invention;  
         [0018]      FIG. 7-2  is a projection view of the first grinding seat and the grinding wheel of the  FIG. 7-1 ;  
         [0019]      FIG. 7-3  is a projection view of the first grinding seat and the grinding wheel of the  FIGS. 7-1  and  7 - 2 ;  
         [0020]      FIG. 8-1  is a perspective view of a drill bit in accordance with the present invention;  
         [0021]      FIG. 8-2  is a top view of the drill bit in accordance with the present invention;  
         [0022]      FIG. 9  is a side view of the drill bit of  FIG. 8-1 ;  
         [0023]      FIG. 10  shows the pivoting portion and the deflection point of the first grinding seat in accordance with the present invention;  
         [0024]      FIG. 11  is an exploded view of the first grinding seat in accordance with the present invention; and  
         [0025]      FIG. 12  is an assembly view of the first grinding seat in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     The present invention will be more clear from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.  
         [0027]     Referring to  FIGS. 1-3 , a double-grinding-wheel type drill bit grinding device with a single driving shaft in accordance with the present invention comprises a power source  10  disposed on a table  100 . Each end of a power shaft  11  of the power source  10  extends out of a supporting member  12  on the table  100  and is connected to a grinding wheel  13 , respectively. A cooling fan  14  is attached to the outer surface of the respective grinding wheels  13 , and at each side of the table  100  is additionally disposed a cover  15  for covering the grinding wheels  13 .  
         [0028]     A first and second grinding seats  20 ,  30  are disposed on top and in front of the respective grinding wheels  13 , respectively. A clamping assembly  40  for claiming a drill bit  99  is arranged on each of the first and second grinding seats  20 ,  30 . On the front surface of the table  100  is disposed more than one positioning device  50  for positioning the clamping assembly  40  and adjusting the relative position between the clamping assembly  40  and the drill bit  99 .  
         [0029]     Each of the first grinding seats  20  includes a base  21 . An arc-shaped slide slot  210  is defined in the bottom of the base  21  for allowing the first grinding seat  20  to be fixed to the table  100  by insertion of a bolt. At the other end of the bottom of the base  21  is formed a pivoting portion  211  to be inserted in the table  100 , so that the base  21  is rotatable around the pivoting portion  211 .  
         [0030]     An eccentric rotating seat  22  is formed on the vertical surface of the base  21 , and two positioning pins  220  are formed on the vertical surface of the rotating seat  22 . The clamping assembly  40  is mounted in and locked by the rotating seat  22 , so that the clamping assembly  40  is rotatable with the rotating seat  22 . The rotating seat  22  is further provided with a flat and straight limit portion  221  located opposite the vertical surface of the base  21 . And two opposite limit pins  212  are formed on the base  21  for limiting the deflection angle of the rotating seat  22  relative to the first grinding seat  20 .  
         [0031]     The second grinding seat  30  includes a base  31  to be positioned on the supporting member  12 , as shown in  FIG. 4 . One end of the base  31  is pivotally connected to the supporting member  12  by a blot  32 , and the other end of the base  31  is provided with a bolt  33  to be inserted and positioned in the supporting member  12 . An end of the central shaft of a cam-controlling element  34  inserted through the supporting member  12  is provided with an abutting member  35  in the form of a cam. The abutting member  35  abuts against the bottom of the base  31  so that the base  31  can change its gradient to meet different cutting requirements. The base  31  is further provided with a limit pin  310  for limiting the deflection angle of the clamping assembly  40  relative to the base  31 .  
         [0032]     The clamping assembly  40  includes a clamping member  41  and a packing member  42  screwed onto the clamping member  41 . In the clamping member  41  is disposed a collet, and at the end of the clamping member  41  is formed a small-diameter receiving portion  410  for insertion of the first and second grinding seats  20 ,  30 . The large-diameter end of the receiving portion  410  is further defined with a flat and straight limit portion  411  so as to limit the position of the clamping member  41  by cooperating with the grinding seats  20 ,  30  and the limiting pins  20  and  310  of the positioning device  50 . The number of the positioning portions  411  is variable according to the number of the number of the cutting edges of the drill bit  99 .  
         [0033]     Referring to  FIG. 5 , the positioning device  50  includes a horizontally arranged base  51 , at one end of the base  51  is formed a receiving portion  510  in the form of a through hole, and a plurality of limit pins  511  is located around the outer periphery of the receiving portion  510  for cooperating with the limiting portions  411  of the clamping member  41  to provide a positioning effect. A column-shaped positioning member  52  is horizontally disposed at the other end of the base  51  and is defined with an inner space for accommodation of an elastic member  53  in the form of a helical spring. A positioning seat  54  is abutted against the top of the positioning member  52 , and in the bottom of the positioning seat  54  is formed positioning concave  540  for cooperating with the positioning member  52 . A central shaft of a fixing member  55  in the form of a screw inserts through the center of the positioning seat  54  and the threaded end of the central shaft of the fixing member  55  is screwed in the bottom of the inner space of the positioning member  52 , so that the positioning seat  54  is fixed to the top of the positioning member  52  by the fixing member  55 . according to this embodiment, the positioning portion  541  of the positioning seat  54  whose peripheral shape being formed correspondingly to the shape of the cutting edge at the sharp end of the drill bit  99  is provided with four cooperating surfaces of different gradients. Therefore, the present invention totally includes two positioning devices  50 , and the positioning seat  54  of each positioning device  50  is provided with a positioning portion  541  with four cooperating surfaces of different gradients, so that the structure of the present invention is applicable to a drill bit  99  with at least more than eight cutting edges.  
         [0034]     Beside the first and second grinding seats  20 ,  30  at both ends of the power source  10 , with reference to  FIG. 6 , the power source  10  can also be provided at its side thereof with another first and second grinding seats  20 ,  30 , so that the grinding device of the present invention is provided with four different grinding seat  20 ,  30  at both ends thereof for meeting different grinding requirements.  
         [0035]     Further, a large storing member  60  in the form of a drawer is disposed in an inner space at the bottom of the table  100 , in the storing member  60  is disposed a holding rack  61  for holding different clamping assemblies  40  applicable for different drill bits  99 .  
         [0036]     The power source  10  of the present invention can be a general electric motor, or a pneumatic motor, as shown in  FIG. 3 . One end of the pneumatic motor is an air-intake end  101 , and the other end is an air-discharge end  102 . An absorbing passage  103  is defined in the table  100  and located at the position of the pneumatic motor, and the open ends of the absorbing passage  103  are located at the two grinding wheels  13 . When the power source  10  operates, a negative pressure is created in the absorbing passage  103 , so that grinding dust produced from the grinding wheels  13  are sucked in the absorbing passage  103  and discharged out of the air-discharge end  102  of the power source  10  and is finally collected. The grinding dust is prevented from being discharged into the surrounding air, therefore, it is environmental friendly.  
         [0037]     The structure of the rotating seat  22  of the base  21  of the first grinding seat  20  is shown in  FIGS. 7-1 ,  7 - 2  and  7 - 3 . On the vertical surface of the base  21  is formed an assembling portion  213  in the form of a hole, the rotating seat  22  is also formed with an assembling portion  222  in the form of a hole for mounting the clamping assembly  40 . The contact point of the axis of the drill bit  99  at the center of the clamping assembly  40  with respect to the surface of the grinding wheel  13  is a central cutting point C. The point of the central cutting point C projected onto the vertical surface of the base  21  is a horizontal-axis point C′. The center of the assembling portion  222  deflects downward to form an eccentric axis point A. When the rotating seat  22  rotates on the base  21  to drive the clamping assembly  40  and the drill bit  99 , the sharp end of the axis of the drill bit  99  is positioned at the central cutting point C, and the peripheral surfaces of the sharp end of the drill bit  99  can rotate along the eccentric axis point A around the horizontal axis point C′ about 90 degrees to produce a cutting and grinding action. Further, the assembling portion  213  of the base  21  is in the form of a slant hole and is provided with a horizontal deflection axis point A′, so that the first deflection axis CA′ of the rotating seat  22  on the base  21  is deflectable within a defection angle of −10-10 degrees relative to the datum axis CC′. And the second deflection axis CA of the assembling portion  222  of the rotating seat  22  is also deflectable at a vertical deflection angle 0-5 degrees with respect to the datum axis CC′. When rotating on the rotating seat  22  of the base  21  during grinding operation, the clamping assembly  40  and the drill bit  99  are allowed to deflect a predetermined distance along the first and second deflection axes CA′ and CA and about the datum axis CC′, so that the peripheral surfaces of the sharp end of the drill bit  99  can be processed simultaneously by the two deflection axes to produce different curvatures and arc-shaped surfaces.  
         [0038]     Referring to  FIGS. 8 and 9 , the center of the sharp end of the drill bit  99  is an apex  990 , the drill bit is provided with two straight cutting edges  991  that extend in the clockwise and counterclockwise directions, respectively to form an arc-shaped cutting extension  992 . At the end of the cutting extension  992  is formed a cutting lip  993  with a certain angle, and a dust-discharge chute  994  is formed next to the cutting lip  993 . The cutting lip  993  extends to the apex  990  to form a slant apex cutting edge  995 . The first grinding seat  20  is used to grind the cutting edges  991  and the cutting portions  992 , and the second grinding seat  30  serves to grind the cutting lip  993  and the apex cutting edge  995 . As compared with the first arc-shaped side line MN cut only by the second defection axis CA, the present invention can also make a second arc-shaped side line M′N′ by using the two deflection axes simultaneously. During the rotation of the drill bit  99 , the apex  990  and the central cutting point C of the drill bit  99  are fixed, only part of the cutting extension  992  is unequally ground at a high speed, as shown in Figure. The amount of deflection of the first deflection axis CA′ relative to the datum axis CC′ is within 0-10 degrees, namely, when it deflects, the cutting extension  992  will move toward the surface of the grinding wheel  13  quickly to deep the grinding depth, so that the curvature of the second arc-shaped side line M′N′ is relatively large. The support force of the cutting edges  991  reduces, and accordingly strength of the cutting edge also reduces, which is suitable for grinding the work piece with a relatively low hardness. When the first deflection axis CA′ is located at a negative angle with respect to the datum axis CC′, the grinding amount of the cutting extension  992  reduces, the second arc-shaped side line M′N′ is relatively flat, the supporting force of the cutting edges  991  is relatively large, and the strength of the drill bit  99  increases substantially, therefore, it is suitable for grinding or cutting the work piece with a relatively high hardness.  
         [0039]     Referring to  FIG. 10 , the pivoting portion  211  of the base  21  is inserted on the pivoting point  211 A of the table  100  to perform compensating displacement around the deflection axis point A′ and can move the deflection point  211 B or  211 C. The assembling portion  213  of the base  21  is kept in the vertical portion of the base  21 , not in the form of a slant hole, such that it can also obtain the effect strengthening the cutting function, as stated above. The same design can also be provided with a deflection member  23  which is disposed between the base  21  and the rotating seat  22  or between the rotating seat  22  and the clamping assembly  40 , and such arrangements can also achieve the same function as mentioned above. For example, the deflection member  23  is disposed between the clamping assembly  40  and the rotating seat  22 , as shown in  FIGS. 11 and 12 , and the deflection member  23  is defined with an inner space  230  for insertion of the clamping assembly  40 . The defection member  23  has a large-diameter flange formed at one end thereof and a small-diameter mounting portion  231  formed at the other end thereof. The hole of the mounting portion  231  is concentric with the center of the rotating seat  22 . The inner space  230  can be shaped in the form of a slant hole according to the slope of the deflection axis point A′, this method can also change the position of the center of the drill bit  99  and achieve the function of multi-axis grinding. The inner space  230  can also be located eccentrically to the center of the mounting portion  231  according to the lengths of the cutting edges  991 , so that it can grind the drill bit  99  with two cutting edges  991  of different lengths.  
         [0040]     Another characteristic of the present invention is that the rear grinding surface  130  of the grinding wheel  13  is shaped in the form of an inward-slanting sharp angle, as shown in  FIG. 9 . The rear grinding surface  130  is maintained at 0-5 degrees with respect to the parallel rear surface, so that the apex cutting edge  995  of the cutting edge  991  close to the apex  990  is formed in a non-vertical form and has an inner slant angle of 0-5 degrees in the vertical direction, so as to reduce the risk of the dust discharge being blocked by the apex cutting edge  995 .  
         [0041]     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.