Patent Abstract:
A band sawing machine has a band saw which runs on a drive wheel and a driven wheel of the band sawing machine. The band sawing machine is provided with a slide seat to which the driven wheel is pivoted. The band sawing machine is provided with an eccentric wheel in contact with the slide seat. The eccentric wheel is turned to bring about a change in diametrical distance, thereby resulting in the up-and-down movement of the slide seat. The distance between the drive wheel and the driven wheel is thus shortened to facilitate the replacing of the band saw.

Full Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a band sawing machine, and more particularly to a band sawing machine with a band saw replaceable rapidly. 
     BACKGROUND OF THE INVENTION 
     The conventional band saw runs on two rollers. As the band saw is worn out, it is replaced by first shortening the distance between the two rollers so as to facilitate the removing of the worn-out band saw from the two rollers. 
     The conventional mechanism for shortening the distance between the two rollers comprises a slide seat which is mounted on the top of the band sawing machine stand. A driven wheel is pivoted to the slide seat which is connected with a threaded rod for regulating the elevation of the slide block, thereby resulting in the change in distance between the two rollers. 
     The conventional mechanism is defective in design in that the driven wheel must be lowered for a considerable distance for replacing the band saw. The control of elevation of the slide block by the threaded rod is inefficient and time-consuming. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a band sawing machine with a band saw which can be replaced with ease and speed. 
     The present invention comprises a machine stand, a drive wheel mounted at the bottom of the machine stand, a driven wheel mounted on the top of the machine stand, a band saw running on the drive wheel and the driven wheel, a slide seat slidably mounted on the machine stand and provided with a press portion. The driven wheel is pivoted on the slide seat. An eccentric wheel is pivoted on the machine stand such that the eccentric wheel is in contact with the bottom side of the press portion of the slide seat, and that the eccentric wheel is connected with a wrenching member capable of turning the eccentric wheel so as to cause the slide seat to engage in the longitudinal displacement to facilitate the replacing of the band saw. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a rear view of a preferred embodiment of the present invention. 
     FIG. 2 shows a partial front view of the preferred embodiment of the present invention to show the position relationship between the driven wheel and the slide seat. 
     FIG. 3 shows a front view of the slide seat as shown in FIG. 2, with the eccentric wheel being located at the first angle position and with the slide seat being located at the upper stop point. 
     FIG. 4 shows a perspective view of the eccentric wheel and the wrenching member of FIG.  2 . 
     FIG. 5 is similar to FIG. 3, with the eccentric wheel being located at the second angle position, and with the slide seat being located at the lower stop point. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIGS. 1 and 2, the band sawing machine of the present invention comprises the following components. 
     A machine stand  10  is formed of a bottom seat  11 , a side pillar  12 , a top seat  13 , and a workbench  14 . The bottom seat  11  is provided with a drive motor  15 . 
     A drive wheel  16  is pivoted in the bottom seat  11  of the machine stand  10  and is driven by the drive motor  15 . 
     A driven wheel  17  is mounted in the top seat  13  such that the axial, line of the driven wheel  17  is parallel to the axial line of the drive wheel  16 . 
     A band saw  18  runs on the drive wheel  16  and the driven wheel  17  such that one side of the band saw  18  is longitudinally put through the workbench  14 . 
     The above components are the prior art structures. The present invention further comprises the following components, as shown in FIG.  3 . 
     A slide seat  20  has an inverted U-shaped cross section with the opening facing forward and is mounted in a longitudinal receiving slot  21  of the interior of the top seat  13  of the machine stand  10  to slide longitudinally. The slide seat  20  is provided at the top end with a cross rod  22  with its both ends extending into the slot hole  23  of the side wall of the receiving slot  21 , thereby preventing the slide seat  20  from slipping out. The slide seat  20  is provided at the bottom end with a longitudinal threaded hole  24 . The slide seat  20  is provided at the top end with a press portion  26 . The press portion  26  of the present invention is the rod body of the cross rod  22 . The slide seat  20  is provided therein with a stop plate  25 . 
     An eccentric wheel  30 , as shown in FIG. 4, is pivoted to the interior of the top seat  13  of the machine stand  10  and is provided with an eccentric axial hole  31  for fitting with a pivoting rod  32  of the shell wall of the top seat  13 . A bolt  33  is put through from the outer peripheral surface to the pivoting rod  32  for fastening the pivoting rod  32  and the eccentric wheel  30 . The eccentric wheel  30  urges upwards the bottom side of the press portion  26  of the slide seat  20  and is provided in the periphery with a long diameter portion  34  separating farther from the axial center, and a short diameter portion  35  separating nearer from the axial center. The eccentric wheel  30  is capable of deflection between a first angle position and a second angle position. As shown in FIG. 3, when it is at the first angle position, the long diameter portion  34  urges upward the press portion  22  of the slide seat  20 , so as to push upwards the slide seat  20  to an upper stop point. When the eccentric wheel  30  is at the second angle position, as shown in FIG. 5, the short diameter portion  35  comes in contact with the press portion  26 . The slide seat  20  is caused by its own weight to descend to a lower stop point. The short diameter portion  35  of the eccentric wheel  30  is planar to enable the eccentric wheel  30  to press against the press portion  26  securely at the time when the eccentric wheel  30  is at the second angle position. A retaining protrusion  38  comes in contact with the cross rod  22  at the time when the eccentric wheel  30  is at the first angle position, thereby bringing about a locating effect. The bolt  33 , which is used to fasten the eccentric wheel  30  and the pivoting rod  32 , is provided at the head with said retaining protrusion. 
     A wrenching member  36  of the present invention is a long rod body, as shown in FIG. 4, which is disposed in the outer portion of the top seat  13  of the machine stand  10  and is connected at one end with the pivoting rod  32 , and at other end with a hand grip  37  which is gripped by hand for turning the eccentric wheel  30 . 
     A seat block  40  is disposed in the slide seat  20  and is located under the stop plate  25  to slide up and down in relation to the slide seat  20 . The driven wheel  30  is pivoted with the seat block  40 . 
     A first elastic member  50  is a rubber block and is held between the top of the seat block  40  and the stop plate  25  of the slide seat  20 . 
     A microadjustment rod  60  is provided at the longitudinal top end with threads which are put through the longitudinal threaded hole  24  of the lower end of the slide seat  20 . The bottom end of the microadjustment rod  60  extends out of the bottom of the top seat  13  and is provided with a wheel-shaped thread motion portion  61  for user to turn to cause the microadjustment rod  60  to displace up and down. The microadjustment rod  60  is provided at the top end with a support portion  62  which is provided at the top with an auxiliary rod  63  extending upwards. The support portion  62  is provided at the front side with a projected point  64 . 
     A second elastic member  70  of the present invention is a spiral spring, which is fitted over the auxiliary rod  63  such that the bottom end of the spring urges the support portion  62 , and that the top end of the spring urges the underside of the seat block  40 . 
     A pointer  80  is pivoted at the center with the top seat  13  of the machine stand  10  and is provided at the tail end with a slot hole  81  which is fitted with the projected point  64 . 
     When the grip  37  of the wrenching member  36  faces downwards, as shown in FIG. 3, the eccentric wheel  30  is at the first angle position to support the slide seat  20  at the upper stop point, thereby resulting in a greater distance between the drive wheel  16  and the driven wheel  17 . As a result, the band saw  18  runs on the drive wheel  16  and the driven wheel  17  at a predetermined tightness. 
     As the thread motion portion  61  of the microadjustment rod is turned, the microadjustment rod  60  is moved upwards such that the second elastic member  63  is compressed by the support portion  62  so as to press against the seat block  40  which is stopped by the first elastic member  50 , thereby resulting in a minute displacement. The driven wheel  17  is also caused to engage in a minute elevation, so as to adjust the tightness of the band saw  18 . As the support portion  62  moves, the pointer  80  is caused to move accordingly to point at a scale (not shown in the drawing). 
     In replacing the band saw  18 , the wrenching member  36  is turned counterclockwise to cause the slide seat  20  to descend to the lower stop point, thereby causing the eccentric wheel  30  to deflect to the second angle position, as shown in FIG.  5 . The driven wheel  17  is actuated by the slide seat  20  to displace downwards, thereby resulting in a reduction in distance between the drive wheel  16  and the driven wheel  17 . The band saw  18  is replaced with ease and speed. As the wrenching member  36  is turned clockwise to return to its normal position, the band saw  18  is ready for service. 
     The advantage of the present invention is that the replacement of the band saw  18  is done by turning the wrenching member  36 . The band saw  18  is actuated by the eccentric wheel  30  to become loosened. As the band saw  18  is replaced, the wrenching member  36  is turned back to tighten the band saw  18 .

Technology Classification (CPC): 8