Patent Publication Number: US-2015071720-A1

Title: Combination cutter and transmission shaft assembly

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to plastic pelletizing technology, and more particularly to a combination cutter and transmission shaft assembly used in a plastic pelletizing machine for making plastic pellets, which prevents perforated plate damage due to an overpressure. 
     2. Description of the Related Art 
     A plastic pelletizing machine for making plastic pellets is known using a motor to rotate a cutter over the surface of a perforated plate to cut off the extruded plastic material into plastic pellets. However, because the cutter is directly and rotatably abutted against the surface of the perforated plate without any buffer, the perforated plate will wear quickly with use. 
     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 combination cutter and transmission shaft assembly for plastic pelletizing machine, which prevents an overpressure damage during operation, prolonging the lifespan of the machine. 
     To achieve this and other objects of the present invention, a combination cutter and transmission shaft assembly of the invention comprises a transmission shaft and a cutter unit. The transmission shaft comprises a tubular shaft body rotatable on the axis thereof and axially movable forward and backward, and a plurality of axial coupling teeth located at a front end of said tubular shaft body. The cutter unit is coupled to and rotatable by the transmission shaft, comprising a cutter holder that comprises an accommodation hole axially defined in one end thereof for receiving the tubular shaft body of the transmission shaft and a plurality of axial coupling grooves axially slidably coupled to the axial coupling teeth of the tubular shaft body, a spring member mounted in the accommodation hole and stopped between an inside wall of the cutter holder and one end of the tubular shaft body of the transmission shaft, and a plurality of cutter blades fastened to one end of the cutter holder remote from the accommodation hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an oblique top elevational view of a part of a plastic pelletizing machine equipped with a combination cutter and transmission shaft assembly used in accordance with the present invention. 
         FIG. 2  is a side view of the plastic pelletizing machine shown in  FIG. 1 . 
         FIG. 3  is an elevational view of the combination cutter and transmission shaft assembly in accordance with the present invention. 
         FIG. 4  is a schematic sectional view illustrating the operation of the present invention (I). 
         FIG. 5  is a schematic sectional view illustrating the operation of the present invention (II). 
         FIG. 6  is a schematic sectional view illustrating the operation of the present invention (III). 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-4 , a combination cutter and transmission shaft assembly in accordance with the present invention is shown used in a plastic pelletizing machine and coupled to a driving mechanism  3 . The combination cutter and transmission shaft assembly comprises a transmission shaft  1  and a cutter unit  2 . 
     The transmission shaft  1  comprises a tubular shaft body  11  rotatable on the axis thereof and axially movable forward and backward, and a plurality of axial coupling teeth  12  equiangularly spaced around an outer perimeter of a front end of the tubular shaft body  11 . 
     The cutter unit  2  comprises a cutter holder  21 , a spring member  23 , a locating member  25 , and a plurality of cutter blades  26 . The cutter holder  21  comprises an accommodation hole  22  axially disposed in one end thereof, a displacement hole  24  axially disposed in an opposite end thereof in communication with the accommodation hole  22 , and a plurality of axial coupling grooves  211  equiangularly spaced around an inner perimeter thereof within the accommodation hole  22  and axially slidably coupled to the axial coupling teeth  12  of the tubular shaft body  11 . The spring member  23  is mounted in the accommodation hole  22  and stopped with its one end against an inside wall of the cutter holder  21  between the accommodation hole  22  and the displacement hole  24  and its other end against the front end of the tubular shaft body  11 . The locating member  25  is movably mounted in the displacement hole  24  and inserted through the spring member  23  into the tubular shaft body  11  of the transmission shaft  1  in the accommodation hole  22  and affixed to the tubular shaft body  11 . The cutter blades  26  are affixed to one end of the locating member  25  outside the cutter holder  21  and rotatable and axially movable with the locating member  25 . 
     The driving mechanism  3  comprises a main drive motor  31 , a driving shaft  32 , a bearing block  33 , and a linear motor  34 . The driving shaft  32  is coupled to and rotatable by the motor  31 , and axially inserted through the tubular shaft body  11  of the transmission shaft  1 . The bearing block  33  is affixed to one end of the tubular shaft body  11  of the transmission shaft  1  and mounted around and rotatable by the driving shaft  32 . Thus, the driving shaft  32  can be driven by the main drive motor  31  to rotate the bearing block  33  and the tubular shaft body  11 . The linear motor  34  is mounted at one side of the bearing block  33  and controllable to move the bearing block  33  and the tubular shaft body  11  axially forward and backward. 
     Referring to  FIGS. 5 and 6  and  FIGS. 2 and 4  again, during operation of the plastic pelletizing machine, the linear motor  34  is controlled to move the bearing block  33  and the tubular shaft body  11  axially forwardly toward a perforated plate  4  to push the spring member  23  against the cutter holder  21 , forcing the cutter blades  26  of the cutter unit  2  into contact with the surface of the perforated plate  4 . When continuously controlling the linear motor  34  to push the tubular shaft body  11  toward the perforated plate  4 , the spring member  23  will be compressed to compensate the displacement of the tubular shaft body  11 , preventing perforated plate damage due to an overpressure in the contact between the cutter blades  26  and the perforated plate  4 . Further, subject to the functioning of the spring member  23  to compensate the displacement of the tubular shaft body  11 , the cutter blades  26  are maintained in positive contact with the surface of the perforated plate  4 .