Patent Publication Number: US-2004045423-A1

Title: Transmission structure of a string saw

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a transmission structure of a string saw, and more particularly to a transmission structure of a string saw, wherein the saw blade may be used to saw the workpiece in a rigid and stable manner, without incurring vibration and noise during the sawing process, thereby enhancing the sawing efficiency and quality.  
       [0003] 2. Description of the Related Art  
       [0004] A conventional string saw in accordance with the prior art comprises an upper suspension arm, a lower suspension arm, a saw blade, a drive lever, and a motor. In operation, the motor may drive the drive lever to move upward and downward to push the lower suspension arm upward and pull the lower suspension arm downward, so that the saw blade may be used to saw a workpiece placed on the work table of the string saw in a vertical manner. However, the saw blade is operated at a high speed, thereby easily incurring vibration and noise during the sawing process, so that the saw blade cannot saw the workpiece in a rigid and stable manner, thereby reducing the sawing efficiency and quality.  
       SUMMARY OF THE INVENTION  
       [0005] The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional string saw.  
       [0006] The primary objective of the present invention is to provide a transmission structure of a string saw, wherein the drive lever, the lower suspension arm, the upper suspension arm, and the saw blade may be moved upward and downward in a rigid and stable manner by balance of the first counterweight and the second counterweight which are arranged in a symmetric manner, so that the saw blade at the high speed may be used to saw the workpiece placed on the work table of the string saw in a rigid and stable manner, without incurring vibration and noise during the sawing process, thereby enhancing the sawing efficiency and quality.  
       [0007] In accordance with the present invention, there is provided a transmission structure of a string saw, comprising an upper suspension arm, a lower suspension arm, a drive lever, a first counterweight, and a second counterweight, wherein:  
       [0008] the drive lever has a top pivotally mounted on the lower suspension arm, so that the lower suspension arm is moved by the drive lever, a bearing is pivotally mounted on a bottom of the drive lever, and has a pivot axle having a first end pivotally mounted on the first counterweight and a second end pivotally mounted on the second counterweight, so that the drive lever, the first counterweight and the second counterweight are moved in concert with each other;  
       [0009] the first counterweight is pivotally mounted on the first end of the pivot axle of the drive lever; and  
       [0010] the second counterweight is pivotally mounted on the second end of the second pivot axle of the second bearing of the drive lever, and is located opposite to the first counterweight, so that the first counterweight and the second counterweight are arranged on two sides of the bottom of the drive lever in a symmetric manner.  
       [0011] Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012]FIG. 1 is a side plan cross-sectional view of a transmission structure of a string saw in accordance with a preferred embodiment of the present invention, wherein the drive lever is moved upward to push the lower suspension arm;  
     [0013]FIG. 2 is a cross-sectional view of the transmission structure of a string saw taken along line  2 - 2  as shown in FIG. 1;  
     [0014]FIG. 3 is a side plan cross-sectional view of the transmission structure of a string saw in accordance with the preferred embodiment of the present invention, wherein the drive lever is moved downward to pull the lower suspension arm;  
     [0015]FIG. 4 is a cross-sectional view of the transmission structure of a string saw taken along line  4 - 4  as shown in FIG. 3;  
     [0016]FIG. 5 is a top plan view of the lower suspension arm of the transmission structure of a string saw in accordance with the preferred embodiment of the present invention; and  
     [0017]FIG. 6 is a top plan view of the transmission structure of a string saw in accordance with the preferred embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0018] Referring to the drawings, a transmission structure of a string saw in accordance with a preferred embodiment of the present invention comprises an upper suspension arm  10 , a lower suspension arm  20 , a drive lever  30 , a first counterweight  37 , a second counterweight  38 , and a motor  40 .  
     [0019] The upper suspension arm  10  is pivotally mounted on the base frame  50  of the string saw by a pivot shaft  11 , so that the upper suspension arm  10  may be pivoted about the pivot shaft  11 .  
     [0020] The lower suspension arm  20  is symmetrically located opposite to the upper suspension arm  10 , and is pivotally mounted on the base frame  50  of the string saw by a pivot shaft  21 , so that the lower suspension arm  20  may be pivoted about the pivot shaft  21 . A saw blade  55  is vertically mounted between a front end of the upper suspension arm  10  and a front end of the lower suspension arm  20 , and is passed through a work table  52  mounted on the base frame  50  of the string saw, so that the saw blade  55  may be used to saw a workpiece placed on the work table  52  of the string saw in a vertical manner. A link  15  is pivotally mounted between a rear end of the upper suspension arm  10  and a rear end of the lower suspension arm  20 , so that the upper suspension arm  10  may be moved in concert with the lower suspension arm  20 . The lower suspension arm  20  has a front side formed with an elongated slot  25  (see FIG. 5).  
     [0021] The drive lever  30  has a top pivotally mounted between two side walls of the elongated slot  25  of the lower suspension arm  20 . Thus, the drive lever  30  may be moved upward and downward reciprocally to push and pull the lower suspension arm  20  synchronously, so that the saw blade  55  may be moved upward and downward reciprocally to saw the workpiece placed on the work table  52  of the string saw in a vertical manner.  
     [0022] Preferably, a first bearing  31  is pivotally mounted on the top of the drive lever  30 , and has a first pivot axle  32  whose two ends are pivotally mounted between the two side walls of the elongated slot  25  of the lower suspension arm  20 .  
     [0023] In addition, a second bearing  35  is pivotally mounted on a bottom of the drive lever  30 , and has a second pivot axle  36  having a first end pivotally mounted on the first counterweight  37  and a second end pivotally mounted on  11  the second counterweight  38 , so that the drive lever  30 , the first counterweight  37  and the second counterweight  38  are moved in concert with each other.  
     [0024] The first counterweight  37  has a sector shape, and is pivotally mounted on the first end of the second pivot axle  36  of the second bearing  35  of the drive lever  30 . The motor  40  has a drive shaft  41  screwed on the first counterweight  37 . Thus, when the drive shaft  41  of the motor  40  is rotated, the first counterweight  37  may be rotated by the drive shaft  41  of the motor  40 , so that the second pivot axle  36  of the second bearing  35  of the drive lever  30  may be driven by the first counterweight  37  to rotate about a periphery of the drive shaft  41  of the motor  40 , so as to move the drive lever  30  upward and downward in a reciprocal manner.  
     [0025] The second counterweight  38  has a sector shape, and is pivotally mounted on the second end of the second pivot axle  36  of the second bearing  35  of the drive lever  30 . The first counterweight  37  and the second counterweight  38  are located at two opposite sides of the bottom of the drive lever  30  symmetrically, so that the drive lever  30  may be moved stably.  
     [0026] In operation, when the drive shaft  41  of the motor  40  is rotated, the first counterweight  37  may be rotated by the drive shaft  41  of the motor  40 , so that the second pivot axle  36  of the second bearing  35  of the drive lever  30  may be driven by the first counterweight  37  to rotate about the drive shaft  41  of the motor  40 , so as to move the drive lever  30  upward and downward in a reciprocal manner. Thus, the drive lever  30  may be moved upward and downward reciprocally to push and pull the lower suspension arm  20  synchronously, so that the saw blade  55  may be moved upward and downward reciprocally to saw the workpiece placed on the work table  52  of the string saw in a vertical manner. In such a manner, the first counterweight  37  and the second counterweight  38  are located at the two opposite sides of the bottom of the drive lever  30  symmetrically, so that the drive lever  30  may be moved rigidly and stably. Thus, the first counterweight  37  and the second counterweight  38  may provide a balance effect, so that the drive lever  30 , the lower suspension arm  20 , the upper suspension arm  10 , and the saw blade  55  may be moved rigidly and stably.  
     [0027] Accordingly, in the transmission structure of a string saw of the present invention, the drive lever  30 , the lower suspension arm  20 , the upper suspension arm  10 , and the saw blade  55  may be moved upward and downward in a rigid and stable manner by balance of the first counterweight  37  and the second counterweight  38  which are arranged in a symmetric manner, so that the saw blade  55  operated at the high speed may be used to saw the workpiece placed on the work table  52  of the string saw in a rigid and stable manner, without incurring vibration and noise during the sawing process, thereby enhancing the sawing efficiency and quality.  
     [0028] Although the invention has been explained in relation to its preferred embodiment as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.