Abstract:
A cutting apparatus adapted for use in a machine tool. The cutting apparatus includes a mounting frame. A cutting unit is mounted rotatably in the mounting frame. A locking unit is connected to the mounting frame and the cutting unit, for restraining or permitting relative movement between the mounting frame and the cutting unit. A driving unit drives rotation of the cutting unit. A control unit controls the driving unit to drive rotation of the rotating shaft upon detecting that the relative movement between the mounting frame and the cutting unit is permitted. The control unit shuts off the driving unit upon detecting that the relative movement between the mounting frame and the cutting unit is restrained.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a cutting apparatus, more particularly to a cutting apparatus for use in a machine tool. 
     2. Description of the Related Art 
     In machining a polygonal rod, i.e., a rod with a polygonal cross-section, a workpiece is first turned by a lathe to form into a circular rod, and then machined by a polygonal turning machine to form the polygonal rod. 
     During the turning operation of the lathe, the workpiece is first held and rotated by a chuck. Then a lathe tool is operated to advance in both radial and axial directions of the workpiece to cut the workpiece, such that a circular rod that has a desired diameter and a desired length is formed at the machined portion of the workpiece. 
     In the forming process of the polygonal rod, the workpiece is held and rotated by a chuck of the polygonal turning machine. Then a polygonal cutter that rotates in a rotational direction the same as that of the workpiece is operated to cut the workpiece into the polygonal rod. 
     However, the removal of the workpiece from the lathe and the loading of the same on the polygonal turning machine are time-consuming and may affect the machining precision. 
     Another conventional machine tool is equipped with a lathe tool and a separate polygonal cutter to respectively perform turning and polygonal turning operations. However, in the machining process of the polygonal rod, the lathe tool and polygonal cutter need to be positioned relative to the workpiece in turn. As a result, the machining precision may still be affected. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the present invention is to provide a cutting apparatus for a machine tool that can serve as a lathe tool and a polygonal cutter. 
     Accordingly, a cutting apparatus of the present invention is adapted for use in a machine tool. The cutting apparatus includes a mounting frame, a cutting unit, a locking unit, a driving unit and a control unit. The cutting unit includes a rotating shaft that is mounted in the mounting frame, and that extends along and is rotatable about an axis, and a cutter assembly that is connected co-rotatably to an end of the rotating shaft along the axis. The locking unit includes a first locking piece that is connected immovably to the mounting frame and that has a first engaging portion, a second locking piece that is connected co-rotatably to the rotating shaft of the cutting unit and that has a second engaging portion, and a latch assembly that surrounds the rotating shaft and that is movable along the axis between a locked position and an unlocked position. The latch assembly engages the first and second engaging portions at the locked position to restrain the rotating shaft from rotating relative to the mounting frame. The latch assembly is separated from the first and second engaging portions at the unlocked position such that the rotating shaft is rotatable relative to the mounting frame. The driving unit is mounted to the mounting frame for driving rotation of the rotating shaft of the cutting unit when the latch assembly is at the unlocked position. The control unit includes a sensor for generating a first signal upon detecting that the latch assembly is at the locked position, and for generating a second signal upon detecting that the latch assembly is at the unlocked position, and a controller that is coupled to the sensor and the driving unit, that controls the driving unit to drive rotation of the rotating shaft upon receipt of the second signal from the sensor, and that controls the driving unit to shut off upon receipt of the first signal from the sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a schematic sectional view of a preferred embodiment of a cutting apparatus according to the invention, illustrating the preferred embodiment serving as a polygonal cutter; 
         FIG. 2  is an enlarged fragmentary sectional view taken from  FIG. 1 , illustrating a latch assembly of the preferred embodiment at an unlocked position; 
         FIG. 3  is a perspective view of a cutter assembly of the preferred embodiment; 
         FIG. 4  is another schematic sectional view of the preferred embodiment, illustrating the preferred embodiment serving as a lathe tool; and 
         FIG. 5  is an enlarged fragmentary sectional view taken from  FIG. 4 , illustrating the latch assembly at a locked position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in  FIGS. 1 and 2 , the preferred embodiment of a cutting apparatus according to the present invention is adapted for use in a machine tool, and includes a mounting frame  10 , a cutting unit  20 , a driving unit  30 , a locking unit  40  and a control unit  50 . 
     The mounting frame  10  has a shaft hole  11  that extends along an axis (L) and that is defined by a first inner surrounding surface, an annular retaining space  101  that extends radially and outwardly from the first inner surrounding surface and terminates at a second inner surrounding surface, and an inner flange  15  that extends radially and inwardly from the second inner surrounding surface. The inner flange  15  substantially divides the annular retaining space  101  into two annular retaining space portions. 
     The cutting unit  20  includes a rotating shaft  21  and a cutter assembly  22 . The rotating shaft  21  extends along the axis (L) through the shaft hole  11  of the mounting frame  10 , and is rotatable about the axis (L). The rotating shaft  21  has opposite first and second end portions  211 ,  212  along the axis (L), and a central portion  213  interconnecting the first and second end portions  211 ,  212 . The second end portion  212  of the rotating shaft  21  is formed with a first positioning structure  214 . In this embodiment, the first positioning structure  214  is configured as a plurality of columns. 
     The cutter assembly  22  includes a base seat  221 , a cutter seat  222  and a plurality of securing members  223 . The base seat  221  is formed with a second positioning structure  225  and a plurality of angularly spaced-apart and circumferentially-extending through grooves  224  (see  FIG. 3 ). In this embodiment, the second positioning structure  225  is configured as a plurality of holes that are engaged respectively with the columns of the first positioning structure  214  for connecting co-rotatably the base seat  221  to the rotating shaft  21 . 
     The cutter seat  222  is connected to the base seat  221 , and is mounted with a plurality of cutters  226 . 
     The securing members  223  extend respectively through the through grooves  224  into the cutter seat  222  for securing the cutter seat  222  to the base seat  221 . Once loosened, securing members  223  are slidable respectively along the through grooves  224  for permitting rotational displacement of the cutter seat  222  relative to the base seat  221 . Therefore, a position of the cutter seat  222  relative to the base seat  221  can be adjusted. 
     The driving unit  30  is mounted to the mounting frame  10 , and includes a motor  31 , a driving pulley  32 , a driven pulley  33  and a belt  34 . The driving pulley  32  is connected co-rotatably to an output shaft of the motor  31 . The driven pulley  33  is connected co-rotatably to the first end portion  211  of the rotating shaft  21 . The belt  34  is trained on the driving and driven pulleys  32 ,  33  for transmitting power from the motor  31  to the rotating shaft  21 . 
     The locking unit  40  includes a first locking piece  41 , a second locking piece  42  and a latch assembly  43 . The latch assembly  43  has a tubular wall segment  431  that surrounds the central portion  213  of the rotating shaft  21 , and first and second flange segments  432 ,  433  that extend radially and outwardly from opposite sides of the tubular wall segment  431  along the axis (L), respectively. An outer surrounding surface of the tubular wall segment  431  is in slidable and fluid-tight contact with an inner periphery of the inner flange  15  of the mounting frame  10 . The first flange segment  432  is disposed in one of the annular retaining space portions of the annular retaining space  101 , and has a periphery in slidable and fluid-tight contact with the second inner surrounding surface of the mounting frame  10 . The first flange segment  432  and the inner flange  15  of the mounting frame  10  cooperatively define a first fluid chamber  13  therebetween. The second flange segment  433  is disposed in the other one of the annular retaining space portions of the annular retaining space  101  that is distal from the first end portion  211  of the rotating shaft  21 , and has a periphery in slidable and fluid-tight contact with the second inner surrounding surface of the mounting frame  10 . The second flange segment  433  and the inner flange  15  of the mounting frame  10  cooperatively define a second fluid chamber  12  therebetween. The second flange segment  433  is formed with an annular engaging portion  434  facing away from the first flange segment  432 . 
     The first locking piece  41  is ring-shaped, and is mounted immovably in the mounting frame  10 . The first locking piece  41  is disposed at one side of the latch assembly  43  distal from the first end portion  211  of the rotating shaft  21 , and is formed with a first engaging portion  411  facing the engaging portion  434  of the second flange segment  433 . 
     The second locking piece  42  is ring-shaped, is surrounded by the first locking piece  41  (i.e., the first locking piece  41  surrounds the second locking piece  42 ), and is sleeved co-rotatably around the central portion  213  of the rotating shaft  21 . The second locking piece  42  is formed with an annular second engaging portion  421  facing the engaging portion  434  of the second flange segment  433  and registered with the first engaging portion  411  of the first locking piece  41 . 
     The latch assembly  43  is movable along the rotating shaft  21  between a locked position (see  FIGS. 4 and 5 ) and an unlocked position (See  FIGS. 1 and 2 ). The latch assembly  43  engages the first and second engaging portions  411 ,  421  at the locked position to restrain the rotating shaft  21  from rotating relative to the mounting frame  10 . The latch assembly  43  is separated from the first and second engaging portions  411 ,  421  at the unlocked position such that the rotating shaft  21  is rotatable relative to the mounting frame  10 . 
     The control unit  50  includes a sensor  51  and a controller  52 . The sensor  51  is disposed on the latch assembly  43  for (generating a first signal upon detecting that the latch assembly  43  is at the locked position, and for generating a second signal upon detecting that the latch assembly  43  is at the unlocked position. The controller  52  is coupled to the sensor  51  and the motor  31  of the driving unit  30  for controlling the motor  31  upon receipt of the signals from the sensor  51 . 
     Referring to  FIGS. 1 and 2 , when a hydraulic fluid is introduced into the first fluid chamber  13 , the latch assembly  43  is actuated to move to the unlocked position. Then the controller  52  controls the motor  31  to drive rotation of the rotating shaft  21  and the cutter assembly  22  upon receipt of the second signal from the sensor  51 . The preferred embodiment of the cutting apparatus therefore serves as a polygonal cutter for performing polygonal turning operation. 
     Referring to  FIGS. 4 and 5 , when the hydraulic fluid is introduced into the second fluid chamber  12 , the latch assembly  43  is actuated to move to the locked position. Then the controller  52  controls the motor  31  to shut down upon receipt of the first signal from the sensor  51 . Since the latch assembly  43  engages the first and second engaging portions  411 ,  421  to restrain the rotating shaft  21  and the cutter assembly  22  from rotating relative to the mounting frame  10 , the preferred embodiment of the cutting apparatus therefore serves as a lathe tool for performing turning operation. 
     To sum up, the cutting apparatus of the preferred embodiment according to this invention is capable of serving as a lathe tool and a polygonal cutter. During the machining process of a polygonal rod, the re-positioning action of cutters relative to a workpiece as with the prior art can be avoided. As a result, a machine tool using the cutting apparatus of the present invention has a better machining precision in comparison with the conventional machine tool. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.