Patent Publication Number: US-2013237133-A1

Title: Grinder equipped with a curved motion mechanism

Description:
FIELD OF THE INVENTION 
     The present invention relates to a machining grinder and particularly to a machining grinder equipped with a curved motion mechanism. 
     BACKGROUND OF THE INVENTION 
     Machining processes usually rely on a machining grinder to process various types machining tools such as gears, worms, drills, milling cutters, hobbing cutters and the like. Such a machining grinder mainly includes a cutting power mechanism, a cutting position adjustment mechanism and a feeding mechanism for an intended working piece. For processing the worms the commonly adopted approach is turning with a cutter. 
     U.S. patent application No. 20090241712 discloses a worm processing manner. It mainly clamps a working piece in a chuck first; next, forms an intended shaping portion at one end of the working piece by turning; then processes a primary helical teeth section on the intended shaping portion via two opposing shape-forming wheels; then clamps the working piece in a chuck and performs precise machining on the helical teeth section via a hobbing cutter inclined at 15 degrees against the axis of the working piece; the hobbing cutter and the working piece are spun at the same speed ratio, and the axes of the hobbing cutter and working piece are maintained at a constant distance to finish the product. 
     While processing the worm by turning can make the finished product in one process at a faster speed to facilitate mass production, there is still room for improvement in terms of precision. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to solve the problem of the conventional technique that processes the worms by turning and results in deficiency in precision. 
     To achieve the foregoing object the present invention provides a grinder equipped with a curved motion mechanism to process a working piece to form a double-envelope structure. The grinder of the invention includes a grinding wheel, a driving shaft, a track bracket and a holder. The grinding wheel includes a grinding edge which has a grinding zone in contact with the working piece. The driving shaft drives the grinding wheel spinning and has a fastening end connecting to the grinding wheel, a free end remote from the fastening end and a middle section between the fastening end and free end. The track bracket holds the driving shaft and is movable in a curved motion against the holder. The driving shaft is coupled with the track bracket via the middle section and driven by the curved motion and tilts against the holder to oscillate about the grinding zone of the grinding wheel as an oscillation center. 
     Through the curved motion of the track bracket against the holder the driving shaft is driven in the oscillation to process the working piece on the grinding zone at varying angles. Thus a worm can be formed with the double-envelope structure, and a multi-angle grinding process also is formed to improve process precision 
     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 perspective view of an embodiment of the invention. 
         FIG. 2  is a schematic view of an embodiment of the invention showing the track bracket and holder in a coupled condition. 
         FIG. 3A  is a schematic view of an embodiment of the invention showing a swivel movement. 
         FIG. 3B  is a schematic view of an embodiment of the invention showing another swivel movement. 
         FIG. 4A  is a schematic view of an embodiment of the invention showing a grinding condition. 
         FIG. 4B  is a schematic view of an embodiment of the invention showing another grinding condition. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Please refer to  FIG. 1  for an embodiment of the invention that is a grinder equipped with a curved motion mechanism to process a working piece  60  to form a double-envelope structure  61  (also referring to  FIGS. 4A and 4B ). The grinder of the invention includes a grinding wheel  10 , a driving shaft  20 , a track bracket  30  and a holder  40 . The grinding wheel  10  has a grinding edge  11 . In this embodiment the grinding edge  11  is an inclined surface, but this is not the limitation, and also can be formed in an arched surface protrusive radially. The grinding edge  11  has a grinding zone  111  in contact with the working piece  60 . The driving shaft  20  drives the grinding wheel  10  spinning and has a fastening end  21  connecting to the grinding wheel  10 , a free end  23  remote from the fastening end  21  and a middle section  22  between the fastening end  21  and free end  23 . 
     Referring to  FIG. 2 , the track bracket  30  is coupled with the middle section  22  of the driving shaft  20 , and has an indented upper curved track  31  and a lower curved track  32  opposing the upper curved track  31 . The holder  40  has an upper latch  41  and a lower latch  42  to latch respectively the upper curved track  31  and lower curved track  32  so that the track bracket  30  is clamped onto the holder  40 . The track bracket  30  further has an elongate gear rack  33  located on the upper curved track  31 . The holder  40  has a transmission gear  43  engaged with the gear rack  33 . The transmission gear  32  also is coupled on a motor  44 . In this embodiment, the transmission gear  43  includes three sets driven by the motor  44 . 
     Referring to  FIG. 1  again, in this embodiment the grinder further includes a rotary seat  50  located at one side of the holder  40  remote from the track bracket  30  and hinged on the holder  40  so that the rotary seat  50  can swivel against the holder  40 . More specifically, take three dimensional coordinates including X-axis, Y-axis and Z-axis as an example, the driving shaft  20  has a spinning axis  24  that can be in parallel with the Y-axis, then the grinding wheel  10  is parallel with a XZ plane formed by the X-axis and Z-axis. When the driving shaft  20  is moved by the curved motion the spinning axis  24  oscillates in parallel with the XY plane and drives the grinding wheel  10  to form an oscillation axis  25  extended from the grinding zone  111  as an axis. The oscillation axis  25  is parallel with the Z-axis. When the rotary seat  50  swivels against the holder  40 , the holder  40  has a swivel axis extended to form a swivel axis  51  parallel with the X-axis, so that the swivel axis  51  swivels against the rotary seat  50 . Also refer to  FIGS. 3A and 3B  for an embodiment of the invention in swivel conditions. In  FIG. 3A , the holder  40  tilts against the rotary seat  50  during swiveling, and the spinning axis  24  and Y-axis form an included angle of negative 30 degrees. Referring to  FIG. 3B , the holder  40  also tilts against the rotary seat  50  during swiveling, but with the spinning axis  24  and Y-axis forming an included angle of positive 30 degrees. 
     Please refer to  FIGS. 4A and 4B  for an embodiment of the invention in grinding conditions. When in use, the working piece  60  is held by a chuck  70  in contact with the grinding zone  111  to receive grinding. During grinding the motor  44  drives the transmission gear  43  which drives the gear rack  33  to move along the upper curved track  31  and lower curved track  32  against the holder  40 , thereby the driving shaft  20  is driven and tilted against the holder  40  to oscillate about the grinding zone  111  as the oscillation center, hence the double-envelope structure can be formed on the working piece  60  by changing the contact angle with the working piece  60  without changing the contact position between the grinding zone  111  and working piece  60 . It is to be noted that during oscillation the spinning axis  24  and the Y-axis are crossed to form an angle no greater than 30 degrees. When the spinning axis  24  and Y-axis are crossed at 30 degrees, the rotary seat  50  swivels against the holder  40  so that the swivel axis  51  and the XY plane are crossed at an angle no greater than 20 degrees. 
     As a conclusion, the invention, through the curved motion of the track bracket against the holder, can drive the driving shaft in oscillation to perform process on the working piece via the grinding zone at different angles to form a worm with the double-envelope structure. In addition, grinding precision improves. Moreover, with the rotary seat hinged on the holder, the grinding zone not only can oscillate horizontally at varying angles, also can swivel vertically increase angle alterations to achieve multi-angle grinding effect, thus is adaptable for grinding of diversified working pieces. It provides significant improvement over the conventional techniques. 
     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.