Abstract:
A grinding machine, which includes a grinding wheel rotatable by a motor, a first slide movable in X-axis direction, a second slide supported on the first slide and movable in Y-direction, a bracket supported on the second slide and turnable about Y-axis, a tool holder supported on the bracket for holding the workpiece for grinding by the grinding wheel, and a driving mechanism for rotating and reciprocating the tool holder.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to grinding machines and more particularly, to a grinding machine for grinding tool bits and milling cutters. 
     2. Description of the Related Art 
     Various grinding machines are known for grinding milling cutters and tool bits. Because different milling cutters and tool bits have different cutting edges and may be made of different materials of different hardness, it requires a special skill to grind different milling cutters and tool bits with conventional grinding machines. It is difficult to accurately and efficiently grind different milling cutters and tool bits with conventional grinding machines simply based on experience. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a grinding machine, which can conveniently be adjusted to fit the angle of the cutting edge of the workpiece so that the cutting edge of the workpiece can be ground accurately and efficiently. According to one aspect of the present invention, the grinding machine comprises a grinding wheel rotatable by a motor, a first slide movable by a first guide screw in X-axis direction, a second slide supported on the first slide and movable by a second guide screw in Y-direction, a bracket supported on the second slide and turnable about Y-axis, a tool holder supported on the bracket for holding the workpiece for grinding by the grinding wheel, and a driving mechanism for rotating and reciprocating the tool holder. According to another aspect of the present invention, the grinding machine further comprises an adjustment block mounted on the first slide, the adjustment block having an axial hole, an inner thread provided inside the axial hole for engagement with the first guide screw, and an adjustment hole axially joining the axial hole at an angle, a spring member connected between the adjustment block and the first slide to hold the adjustment block in an engagement position where the inner thread is kept meshed with the first guide screw to prohibit movement of the first slide relative to the first guide screw when the first guide screw stands still, and a handle fastened to the adjustment block for pulling by hand to move the adjustment hole into a parallel position relative to the first guide screw where the inner thread is disengaged from the first guide screw for allowing quick position adjustment of the first slide relative to the first guide screw. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a grinding machine according to the present invention. 
         FIG. 2  is a schematic drawing showing the tool holder of the grinding machine adjusted in Y-axis direction according to the present invention. 
         FIG. 3  is a schematic drawing showing adjustment of the tilting angle of the tool holder of the grinding machine according to the present invention. 
         FIG. 4  is a schematic drawing showing adjustment of horizontal angle of the tool holder of the grinding machine according to the present invention. 
         FIG. 5  is an exploded view of a part of the present invention, showing the structure of the tool holder. 
         FIG. 6  is an exploded view of a part of the present invention, showing the relative positioning between the rear side of the tool holder and the drive bevel gear. 
         FIG. 7  is a schematic side view of the present invention, showing the chuck rotated and reciprocated. 
         FIG. 8  is a schematic drawing showing the first guide screw meshed with the locating block according to the present invention. 
         FIG. 9  corresponds to  FIG. 8 , showing the first guide screw disengaged from the locating block, the first slide adjusted relative to the first guide screw. 
         FIG. 10  is a schematic drawing of the present invention, showing the tool holder moved with the second slide and the first slide relative to the first guide screw. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 and 2 , a grinding machine comprises a grinding unit, a workpiece driving unit, and a machine base  3  supporting the grinding unit and the workpiece driving unit. The grinding unit comprises a motor  1  fixedly mounted on the machine base  2 , and a grinding wheel  11  coupled to and rotatable by the motor  1 . The workpiece driving unit comprises a first guide screw  3  pivotally mounted on the machine base  2  at the top side in horizontal and extending in X-axis direction, a first slide  32  coupled to the first guide screw  3  and movable forwards/backwards in X-axis direction upon rotation of the first guide screw  3  in clockwise/counter-clockwise direction, a locating block  5  mounted on the first slide  32 , a second guide screw  4  pivotally mounted in the locating block  5  and extending in Y-axis direction in parallel to the center axis of the grinding wheel  11 , a second slide  42  coupled to the second guide screw  4  and movable forwards/backwards in Y-axis direction upon rotation of the second guide screw  4  in clockwise/counter-clockwise direction, a first knob  31  fixedly fastened to one end of the first guide screw  3  for operation by the user to rotate the first guide screw  3 , a second knob  41  fixedly fastened to one end of the second guide screw  4  for operation by the user to rotate the second guide screw  4 , a rack  52  horizontally rotatably mounted on the second slide  42  (see  FIG. 4 ), a bracket  53  pivotally mounted on the rack  52  and locked thereto by a screw bolt  521  for allowing the bracket  53  to be turned about Y-axis after loosened the screw bolt  521  (see  FIG. 3 ), an axle sleeve  67  fixedly mounted on the bracket  53 , and a tool holder  6  mounted in the axle sleeve  67 . The tool holder  6  comprises a barrel  61  mounted in the axle sleeve  67 , a shaft  621 , and a chuck  62  mounted on one end of the shaft  621 . A screw  611  is mounted in the barrel  61  and threaded into a longitudinal groove  622  at the periphery of the shaft  621  to secure the shaft  621  to the barrel  61  (see  FIG. 5 ), allowing axial movement of the shaft  621  relative to the barrel  61  and rotary motion with the barrel  61 . The tool holder  6  further comprises a driven bevel gear  64  fixedly mounted on the rear end of the barrel  61  and meshed with a drive bevel gear  65 , which is pivotally mounted on the bracket  53  and rotatable by a hand wheel  54  (or belt wheel). A universal joint  63  is pivotally mounted in one end of the shaft  621  to support an extension axle  631 . The drive bevel gear  65  has an eccentric rod  651  perpendicularly extending from the front side thereof, and a screw hole  652  on the front side near the periphery. An eccentric wheel  66  is coupled between the extension axle  631  and the drive bevel gear  65 . The eccentric wheel  66  comprises a recessed coupling hole  663  disposed at the back side at an eccentric location and coupled to the eccentric rod  651 , a front coupling rod  664  perpendicularly extending from the front side and coupled to the extension axle  631 , and an arched sliding slot  661  cut through the front and back side near the periphery. A lock screw  662  is inserted through the arched sliding slot  661  and threaded into the screw hole  652  to adjustably lock the eccentric wheel  66  to the drive bevel gear  65  at the desired angle. When operating the hand wheel  54  to drive the drive bevel gear  65  to rotate the driven bevel gear  64  and the barrel  61 , the shaft  621  and the chuck  62  are simultaneously rotated with the barrel  61 , and at the same time the eccentric wheel  66  is alternatively rotated forwards and backwards to reciprocate the extension axle  631  and the shaft  621  with the chuck  62  (see  FIGS. 6 and 7 ). By means of changing the angular position of the eccentric wheel  66  relative to the drive bevel gear  65 , the reciprocating distance and cycle of the extension axle  631  is relatively changed. After installation of the workpiece (milling cutter or tool bit)  7  in the chuck  62 , the first guide screw  3  and the second guide screw  4  are rotated to adjust the position of the first slide  32  and the second slide  42  in X-axis and Y-axis directions respectively. Thereafter, adjust the angular position of the bracket  53  so as to adjust the tilting angle of the chuck  62  and the workpiece  7 . Further, the locating block  5  has an arched sliding slot  51  through which an adjustment screw  511  is inserted and threaded into the first slide  32  to lock the locating block  5  to the first slide  32 . When the adjustment screw  511  is loosened, the locating block  5  can be turned horizontally to adjust the angle between the workpiece  7  and the outer edge of the grinding wheel  11 . 
     Referring to  FIGS. 8˜10 , an adjustment block  33  is mounted on the first slide  32 , having an axial hole  332 , an inner thread  3321  provided inside the axial hole  332  for engagement with the first guide screw  3 , an adjustment hole  331  axially joining the axial hole  332  at an angle, a spring member  334  connected between the adjustment block  33  and the first slide  32  to hold the adjustment block  33  in an engagement position where the inner thread  3321  is kept meshed with the first guide screw  3  to prohibit movement of the first slide  32  relative to the first guide screw  3  when the first guide screw  3  stands still, and a handle  333  fastened to the adjustment block  33  for pulling by hand to move the adjustment hole  331  into a parallel position relative to the first guide screw  3  where the inner thread  3321  is disengaged from the first guide screw  3  for allowing quick position adjustment of the first slide  32  relative to the first guide screw  3 . 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention.