Patent Publication Number: US-2005120853-A1

Title: Power cutting tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims priority of Taiwanese application no. 092221550, filed on Dec. 8, 2003.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The invention relates to a cutting tool, more particularly to a power cutting tool that can facilitate cutting of relatively hard objects.  
      2. Description of the Related Art  
      Referring to  FIG. 1 , a conventional cutting tool  1  is shown to include a pair of handle members  11  connected pivotally to each other, and a pair of blade members  12  connected pivotally to front ends of the blade members  11 . The blade members  12  are further connected pivotally to each other.  
      In use, when the handle members  11  are pressed toward each other, the blade members  12  will be driven to move toward each other to permit cutting of an object  10  that is disposed between the blade members  12 .  
      The aforesaid conventional cutting tool  1  is disadvantageous in that the user must exert a large force when cutting a relatively hard object  10 , such as a stem of an artificial plant.  
     SUMMARY OF THE INVENTION  
      Therefore, the object of the present invention is to provide a power cutting tool that can facilitate cutting of relatively hard objects.  
      According to the present invention, a power cutting tool comprises an electric driving unit and a cutting unit. The electric driving unit includes a rotary driving member. The cutting unit includes a first cutting member and a second cutting member pivotable relative to the first cutting member. The second cutting member is driven by the rotary driving member such that rotation of the rotary driving member results in pivoting movement of the second cutting member relative to the first cutting member for cutting an object disposed between the first and second cutting members. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:  
       FIG. 1  is a schematic view to illustrate a conventional cutting tool;  
       FIG. 2  is a schematic partly sectional view of the first preferred embodiment of a power cutting tool according to the present invention;  
       FIG. 3  is a fragmentary schematic partly sectional view to illustrate a cutting state of the first preferred embodiment;  
       FIG. 4  is a schematic view to illustrate operation of a rotary drive member of the first preferred embodiment;  
       FIG. 5  is a fragmentary schematic partly sectional view to illustrate the second preferred embodiment of a power cutting tool according to the present invention; and  
       FIG. 6  is a view similar to  FIG. 5 , but illustrating a cutting state of the second preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.  
      Referring to  FIGS. 2 and 3 , the first preferred embodiment of a power cutting tool  2  according to the present invention is shown to comprise a casing  3 , an electric driving unit  4 , and a cutting unit  5 .  
      The casing  3  includes a handle portion  31  and a mounting portion  32  generally transverse to the handle portion  31 . The handle portion  31  is adapted for gripping by the user of the power cutting tool  2 , and has a power switch  311  mounted thereon. The mounting portion  32  confines a mounting space  33  therein.  
      The electric driving unit  4  is mounted in the mounting space  33 , and includes a power mechanism  41  and a rotary driving member  42  disposed in front of and driven rotatably by the power mechanism  41 . In this embodiment, the power mechanism  41  includes an electric motor and a speed reduction device. Since the specific construction of the power mechanism  41  is known in the art and is not pertinent to the claimed invention, a detailed description of the same is omitted herein for the sake of brevity.  
      With further reference to  FIG. 4 , the rotary driving member  42  includes a circular base plate  421  and a cylindrical drive post  422  extending from the base plate  421 . The base plate  421  is coupled to and is driven by the power mechanism  41  to rotate about an axis (X). The drive post  422  extends forwardly from the base plate  421 , and extends parallel to and is offset from the axis (X). In this embodiment, the drive post  422  is disposed proximate to a peripheral edge of the base plate  421 .  
      The cutting unit  5  is disposed in front of the electric driving unit  4  and is used to cut an object  20 . The cutting unit  5  includes a first cutting member  51 , a second cutting member  52 , and a biasing member  53 .  
      The first cutting member  51  includes a mounting section  511  having front and rear ends, a first pivot section  512  connected to the front end of the mounting section  511 , and a first blade section  513  extending forwardly from the pivot section  512 . In this embodiment, the electric driving unit  4  has opposite first and second sides (i.e., upper and lower sides) relative to the axis (X), and the rear end of the mounting section  511  is disposed to be fixed relative to the first (upper) side of the electric driving unit  4 . Preferably, the rear end of the mounting section  511  is fixed directly to the first (upper) side of the electric driving unit  4 .  
      The second cutting member  52  includes a second pivot section  521  connected pivotally to the first pivot section  512  of the first cutting member  51  by a pivot  50 , a driven section  522  extending rearwardly from the second pivot section  521  and driven by the rotary driving member  42 , and a second blade section  523  extending forwardly from the pivot section  521 . The driven section  522  abuts against the drive post  422  of the rotary driving member  42 . With further reference to  FIG. 4 , the drive post  422  moves along a circular path (P) upon rotation of the base plate  421 . The driven section  522  of the second cutting member  52  is formed with a driven end that is remote from the second pivot section  521  and that extends in a chordal direction relative to the circular path (P) of the drive post  422 .  
      In this embodiment, the biasing member  53  is a compression spring that is disposed between and that has opposite ends abutting respectively against the mounting section  511  of the first cutting member  51  and the driven section  522  of the second cutting member  52 . The biasing member  53  provides an urging force to maintain abutment between the driven section  522  of the second cutting member  52  and the drive post  422  of the rotary driving member  42 . In this embodiment, the biasing member  53  biases the driven section  522  away from the mounting section  511  of the first cutting member  51 , i.e., away from the first (upper) side of the electric driving unit  4 , thereby moving the first and second blade sections  513 ,  523  of the first and second cutting members  51 ,  52  away from each other.  
      In use, the power switch  311  on the handle portion  31  of the casing  3  is operated to activate the power mechanism  41  of the electric driving unit  4 . When the base plate  421  of the rotary driving member  42  is driven rotatably by the power mechanism  41 , the drive post  422  will move along the circular path (P) from the second (lower) side of the electric driving unit  4  to the first (upper) side of the electric driving unit  4 . Since the driven section  522  of the second cutting member  52  abuts against the drive post  422 , the driven section  522  of the second cutting member  52  will be moved from an initial position remote from the mounting section  511  of the first cutting member  51  (see  FIG. 2 ) to a cutting position proximate to the mounting section  511  of the first cutting member  51  (see  FIG. 3 ) against the biasing action of the biasing member  53 . As the driven section  522  moves from the initial position to the cutting position, the second cutting member  52  pivots relative to the first cutting member  51  about the pivot  50  to bring the second blade section  523  toward the first blade section  513  of the first cutting member  51 , thereby cutting the object  20  that is disposed between the first and second blade sections  513 ,  523 .  
      Thereafter, when the power mechanism  41  continues to drive rotation of the base plate  421  of the rotary driving member  42  about the axis (X), the drive post  422  will move along the circular path (P) from the first (upper) side of the electric driving unit  4  back to the second (lower) side of the electric driving unit  4 . As a result, the driven section  522  of the second cutting member  52  will be moved from the cutting position back to the initial position through the biasing action of the biasing member  53 , and the second cutting member  52  pivots relative to the first cutting member  51  about the pivot  50  to bring the second blade section  523  away from the first blade section  513  of the first cutting member  51  in preparation for another cutting operation.  
       FIGS. 5 and 6  illustrate the second preferred embodiment of a power cutting tool  2   a  according to the present invention. The power cutting tool  2   a  of this embodiment differs from the previous embodiment in the construction of the cutting unit  6 .  
      In this embodiment, the cutting unit  6  is similarly disposed in front of the electric driving unit  4  and is used to cut an object  20 . The cutting unit  6  includes a first cutting member  61 , a second cutting member  62 , a pivot connection member  63 , and a biasing member  64 .  
      The first cutting member  61  includes a mounting section  611  having front and rear ends, a connecting section  612  connected to the front end of the mounting section  611 , and a first blade section  613  extending forwardly from the connecting section  612 . In this embodiment, the electric driving unit  4  has opposite first and second sides (i.e., lower and upper sides) relative to the axis (X) of rotation of the base plate  421  of the rotary driving member  42 , and the rear end of the mounting section  611  is disposed to be fixed relative to the first (lower) side of the electric driving unit  4 . Preferably, the rear end of the mounting section  611  is fixed directly to the first (lower) side of the electric driving unit  4 .  
      The second cutting member  62  includes a pivot section  621 , a driven section  622  extending rearwardly from the pivot section  621  and driven by the rotary driving member  42 , and a second blade section  623  extending forwardly from the pivot section  621 . The driven section  622  abuts against the drive post  422  of the rotary driving member  42 . The relationship between the driven section  622  and the drive post  422  is the same as that described hereinabove in connection with the previous embodiment.  
      In this embodiment, the pivot connection member  63  includes a pair of connection plates that are disposed on opposite sides of the first and second cutting members  61 ,  62 , that are connected fixedly to the connecting section  612  of the first cutting member  61 , and that are connected pivotally to the pivot section  621  of the second cutting member  62 , thereby permitting pivoting movement of the second cutting member  62  relative to the first cutting member  61  in response to rotation of the rotary driving member  42 .  
      In this embodiment, the biasing member  64  is an extension spring that is disposed between and that has opposite ends connected respectively to the mounting section  611  of the first cutting member  61  and the driven section  622  of the second cutting member  62 . The biasing member  64  provides an urging force to maintain abutment between the driven section  622  of the second cutting member  62  and the drive post  422  of the rotary driving member  42 . In this embodiment, the biasing member  64  biases the driven section  622  toward the mounting section  611  of the first cutting member  61 , i.e., toward the first (lower) side of the electric driving unit  4 , thereby moving the first and second blade sections  613 ,  623  of the first and second cutting members  61 ,  62  away from each other.  
      In use, when the base plate  421  of the rotary driving member  42  is driven rotatably by the power mechanism  41 , the drive post  422  will move from the first (lower) side of the electric driving unit  4  to the second (upper) side of the electric driving unit  4 . Since the driven section  622  of the second cutting member  62  abuts against the drive post  422 , the driven section  622  of the second cutting member  62  will be moved from an initial position proximate to the mounting section  611  of the first cutting member  61  (see  FIG. 5 ) to a cutting position remote from the mounting section  611  of the first cutting member  61  (see  FIG. 6 ) against the biasing action of the biasing member  64 . As the driven section  622  moves from the initial position to the cutting position, the second cutting member  62  pivots relative to the first cutting member  61  to bring the second blade section  623  toward the first blade section  613  of the first cutting member  61 , thereby cutting the object  20  that is disposed between the first and second blade sections  613 ,  623 .  
      Thereafter, when the power mechanism  41  continues to drive rotation of the base plate  421  about the axis (X), the drive post  422  will move from the second (upper) side of the electric driving unit  4  back to the first (lower) side of the electric driving unit  4 . As a result, the driven section  622  of the second cutting member  62  will be moved from the cutting position back to the initial position through the biasing action of the biasing member  64 , and the second cutting member  62  pivots relative to the first cutting member  61  to bring the second blade section  623  away from the first blade section  613  of the first cutting member  61  in preparation for another cutting operation.  
      In sum, the power cutting tool ( 2 ,  2   a ) of this invention permits the cutting of relatively hard objects without requiring the user to exert a large force.  
      While the present invention has been described in connection with what is considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments 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.