Abstract:
With a conventional baling machine, for tying an article resting on a pallet with a band, the article resting on the pallet is required to be placed in a frame of an arch guide. To solve this problem, the present invention provides a baling machine including a main body having a band feeding mechanism, a band bonding mechanism, and a band cutting mechanism; a vertical table ( 3 ) to be aligned with an article resting on a pallet; a band guide ( 7 ) provided to be drawn out from under the vertical table ( 3 ) in a horizontal direction; a support mechanism for supporting the band guide ( 7 ) inside the main body allowing it to slide; and wheels ( 17 ) provided to the main body, wherein the band guide ( 7 ) slides above the ground contact face of the wheels ( 17 ).

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a baling machine for tying an article with a band, more particularly, to a baling machine for tying an article resting on a pallet or like together with the pallet or the like by means of a band.  
           [0003]    2. Description of Related Art  
           [0004]    [0004]FIG. 19 is a diagram illustrating an article w resting on a pallet  50 . The pallet  50  is composed of a top plate  51 , a bottom plate  53  and vertical plates  52  connecting between the top plate  51  and the bottom plate  53 . The article w resting on such a pallet  50  is tied together with the pallet by means of a band. FIG. 18 illustrates a conventional baling machine used in such a band-tying operation.  
           [0005]    The conventional baling machine illustrated in FIG. 18 includes a main body  100  which is provided with a sealing unit  101  for tightening, bonding and cutting the band B, and a reel unit  102  for holding the band B.  
           [0006]    On the sealing unit  101  and a base  104 , an arch guide  103  is secured adjacent to the main body  100 . The chain lines in FIG. 18 represent a lower guide  105  which is typically housed in the main body  100 . The main body  100  includes a mechanism for moving the lower guide  105  in a horizontal direction from the main body  100  to the outside, and vice-versa.  
           [0007]    In the band-tying operation, the lower guide  105  moves from an opening  106  toward the left in FIG. 18 to connect with a connecting port  107  of the arch guide  103 . In order to make a proper connection between the lower guide  105  and the connecting port  107 , the main body  100  and the arch guide  103  are fixed on the floor of a building.  
           [0008]    When the conventional baling machine as explained above is used for tying the article w resting on the pallet  50  with the band B, the following steps are performed. First, an article w resting on a pallet  50  is placed on the base  104  in such a way that it is aligned with a side face of the sealing unit  101 .  
           [0009]    Then an operator pushes an operation button of the main body  100 , whereupon the lower guide  105  moves leftward in FIG. 18 to pass through the space between the top plate  51  and the bottom plate  53  of the pallet  50  from the opening  106 , and then connects with the arch guide  103 .  
           [0010]    Then, the band B unreeled from the reel unit  102  of the main body  100  reaches the arch guide  103  via the sealing unit  101 , the lower guide  105 , and the connecting port  107 . The band B moves inside the arch guide  103  to return to the sealing unit  101 . After the leading end of the band returns to the inside of the sealing unit  101 , the sealing unit  101  tightens, bonds and cuts the band B. After that, the lower guide  105  moves into the main body  100  for housing. In this way, the article w is tied together with the pallet  50  by means of the band B.  
           [0011]    The conventional baling machine designed as described above includes the arch guide  103 . For this reason, when the article w resting on the pallet  50  is inserted in the frame of the arch guide  103  by using a forklift truck, the following problem arises.  
           [0012]    When the article w resting on the pallet  50  is inserted in the frame of the arch guide  103 , the pallet  50  is placed on the base  104 . Hence, it is necessary to provide a conveyor on one or other side of the base  104 . More specifically, due to a heavy weight of the article w on the pallet  50 , it is necessary that the forklift truck is operated to place the article w resting on the pallet  50  first on the conveyor, then on the base  104 . This produces a problem of a low workability.  
           [0013]    Further, since the baling machine body  100  and the arch guide  103  are fixed on the floor of the building, it is necessary for a worker to convey the pallet  50  and the article w to their position in the frame of the arch guide  103 .  
         SUMMARY OF THE INVENTION  
         [0014]    It is an object of the present invention to provide a baling machine capable of facilitating the tying of an article resting on a pallet with a band.  
           [0015]    As a first aspect, the present invention has the feature that a baling machine includes a main body including a band feeding mechanism, a band bonding mechanism, and a band cutting mechanism; a vertical table to be aligned with an article resting on a pallet; a band guide provided to be drawn out from under the vertical table in a horizontal direction; a support mechanism for supporting the band guide inside the main body and allowing the band guide to slide; and wheels provided to the main body, in which the band guide slides above the ground contact face of the wheels.  
           [0016]    According to the first aspect, the provision of the wheels to the main body enables the main body to be moved to the site of the article resting on the pallet or the like and the vertical table on the main body to be aligned with the article. As long as the vertical table on the main body is aligned with the article, the band guide can be inserted under the pallet or the like, so that the band guided by the band guide can be passed under the pallet or the like. Consequently, it is possible to pass the band under the pallet or the like without moving the article resting on the pallet.  
           [0017]    As a second aspect, the present invention has the feature that the band guide is supported only by the support mechanism provided in the main body.  
           [0018]    According to the second aspect, since the band guide is supported only by the support mechanism provided in the main body, the band guide is supported while being drawn out from the main body.  
           [0019]    As a third aspect, the present invention has the feature that the support mechanism includes a retainer member for inhibiting the turning of a leading end of the band guide toward the ground contact of the wheels.  
           [0020]    According to the third aspect, even when the band guide is drawn out from the main body, there is no chance of the leading end of the band guide making a downward inclination.  
           [0021]    As a fourth aspect, the present invention has the feature that the support mechanism includes a stop mechanism for determining a selected position for drawing out the band guide.  
           [0022]    According to the fourth aspect, since the band guide can be stopped at a selected position, the extent of drawing out the band guide can be determined in correspondence with the size of the pallet or the like.  
           [0023]    As a fifth aspect, the present invention has a feature that the main body further includes a band tightening mechanism including an input member linked to an output shaft of a motor serving as a power source, an output member linked to a tension roller for pulling the band, and a powder clutch for engaging or disengaging the input member with or from the output member, and torque transferred from the input member to the output member is varied in accordance with excitation current applied to the powder clutch.  
           [0024]    According to the fifth aspect, the band tightening mechanism includes the powder clutch. With such band tightening mechanism, a strength of the fixation between the rotor and the shaft can be changed in accordance with a magnitude of the excitation current passing through the coil of the powder clutch, to vary torque transferred from the rotor to the shaft. Since the torque transferred from the rotor to the shaft is thus varied, it is possible to control a force of tightening the band. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    [0025]FIG. 1 is an external perspective view of a baling machine according to the present invention.  
         [0026]    [0026]FIG. 2 is a side view of the baling machine.  
         [0027]    [0027]FIG. 3 is a sectional view of a band guide.  
         [0028]    [0028]FIG. 4 is a side view of the band guide.  
         [0029]    [0029]FIG. 5 is a top view of a clamp lever.  
         [0030]    [0030]FIG. 6 is a side view of a band-guide moving mechanism according to a second embodiment.  
         [0031]    [0031]FIG. 7 is a back view of the band-guide moving mechanism according to the second embodiment.  
         [0032]    [0032]FIG. 8 is a top view of the band-guide moving mechanism according to the second embodiment.  
         [0033]    [0033]FIG. 9 is a side view of a band-guide moving mechanism according to a third embodiment.  
         [0034]    [0034]FIG. 10 is a back view of the band-guide moving mechanism according to the third embodiment.  
         [0035]    [0035]FIG. 11 is a side view of a band-guide moving mechanism according to a fourth embodiment.  
         [0036]    [0036]FIG. 12 is a side view of a band-guide moving mechanism according to a fifth embodiment.  
         [0037]    [0037]FIG. 13 is a top view of the band-guide moving mechanism according to the fifth embodiment.  
         [0038]    [0038]FIG. 14 is a side view of a band-guide moving mechanism according to a sixth embodiment.  
         [0039]    [0039]FIG. 15 is a side view of a band-guide moving mechanism according to a seventh embodiment.  
         [0040]    [0040]FIG. 16 is a diagram illustrating a structure of a band tightening mechanism.  
         [0041]    [0041]FIG. 17 is a half-sectional view illustrating a structure of a powder clutch.  
         [0042]    [0042]FIG. 18 is a diagram illustrating a conventional baling machine.  
         [0043]    [0043]FIG. 19 is a diagram illustrating the state when an article is rested on a pallet. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0044]    [0044]FIG. 1 is a perspective view illustrating a first embodiment according to the present invention. A main body  1  holds a reel unit  2  allowing it to rotate and has a side face serving as a vertical table  3 .  
         [0045]    Inside the vertical table  3 , a band feeding mechanism, a band tightening mechanism, a band bonding mechanism and a band cutting mechanism are incorporated. FIG. 2 is a side view illustrating the first embodiment. Reference numeral  60  represents the band tightening mechanism.  
         [0046]    The above individual mechanisms in the first embodiment are arranged along the vertical table  3 , whereas the corresponding mechanisms in the conventional baling machines are arranged along a horizontal table.  
         [0047]    The band tightening mechanism  60  will be described later. The band bonding mechanism and the band cutting mechanism are the same as those used in the prior art and the description is omitted.  
         [0048]    As illustrated in FIG. 2, a band B having passed through all the above mechanisms is guided by a stationary guide  4  and an arcuate guide  5  continuing from the stationary guide  4  to reach the bottom portion of the main body  1 .  
         [0049]    On the bottom portion of the main body  1 , a recess-shaped holder  6  is provided. The holder  6  has a bottom face  6   a  and two side walls  6   b  provided along either side of the bottom face  6   a . In the holder  6 , a band guide  7  is provided moving in a horizontal direction, of which the sectional form is illustrated in FIG. 3.  
         [0050]    Specifically, the band guide  7  has a bottom plate  7   a  on which a pair of guide pieces  7   b  are provided in an upright position at a predetermined interval. From the opposite faces of the guide pieces  7   b , introductory guide pieces  7   c  protrude on either side. From each of the top ends of the guide pieces  7   b , a horizontal piece  7   d  protrudes outward.  
         [0051]    The above bottom plate  7   a , guide piece  7   b , introductory guide piece  7   c  and horizontal piece  7   d  continue in the longitudinal direction of the band guide  7 .  
         [0052]    The band guide  7  designed as described above is supported by a support mechanism provided in the main body  1 . As illustrated in FIG. 3, the support mechanism is composed of a bottom-plate support member  8 , a side-face support member  9  and a retainer member  10  which is a feature of the present invention, all of which are arranged so as to surround the band guide  7  and allow it to slide. Specifically, the bottom plate  7   a  of the band guide  7  is placed so as to slide on the bottom-plate support member  8 . Each of the side portions of the bottom plate  7   a  and the horizontal piece  7   d  in the width direction is retained by the side-face support member  9  to prevent rolling. Additionally, the horizontal piece  7   d  is retained by the retainer member  10  so as not to move upward.  
         [0053]    Accordingly, the band guide  7  is supported by the support mechanism so as to slide while being prevented from rattling. However, the band guide  7  is not completely prevented from rattling, but is prevented from rattling to the extent of interfering with the operation of the band guide  7 .  
         [0054]    Due to the sliding facility provided to the band guide  7  by the support mechanism, the band guide  7  can be drawn out outward from the main body  1  as illustrated in FIG. 1. Even while the band guide  7  is thus being drawn out, the band guide  7  is supported by the support mechanism so that its leading end does not touch the ground.  
         [0055]    A stop mechanism S is provided for determining the point to which the band guide  7  is drawn out. As illustrated in FIG. 3, the stop mechanism S has a rod  11  as a principal element which passes through the side walls  6   b  of the aforementioned holder  6 . Specifically, the rod  11  has one penetrating-end on which a nut  12  is secured and the other penetrating-end on which a hole  13  is provided. The hole  13  is provided with a shaft  14  on which an operation member  15  is rotatably mounted.  
         [0056]    As illustrated in FIG. 5, the operation member  15  has a lever  15   a  and a cam  15   b  provided at an end of the lever  15   a . The rotation of the cam  15   b  allows the operation member  15  to come into contact with one of the side walls  6   b  or move away therefrom.  
         [0057]    When the operation member  15  is situated at the position indicated by the solid line in FIG. 5, the cam  15   b  is separated from the side wall  6   b . Then when the lever  15   a  is turned to hold the operation member  15  in the position indicated by the chain line in FIG. 5, the cam  15   b  comes into contact with one of the side walls  6   b  and presses it, and the reaction force of the pressing force pulls the rod  11 . The force pulling the rod  11  in turn draws the other side wall  6   b.    
         [0058]    In other words, when the operation member  15  is held in the position indicated by the solid line in FIG. 5, the space between the pair of opposite side walls  6   b  is maintained in its normal state. However, when the operation member  15  is held in the position of the chain line, the space between the pair of opposite side walls  6   b  is decreased.  
         [0059]    When the space between a pair of opposite side walls  6   b  is decreased, the band guide  7  is clamped to the extent of the decreased space by the side-face support members  9 , and is stopped at a predetermined position by the clamping force of the side-face support members  9 .  
         [0060]    With respect to a space L 1  between the guide pieces  7   b  on the bottom plate  7   a  of the band guide  7 , a space L 2  between the introductory guide pieces  7   c  is sufficiently small. The space L 2  is slightly larger than the width of the band B and the aforementioned arcuate guide  5  is inserted into the space L 2 .  
         [0061]    Accordingly, the band B guided along the arcuate guide  5  is guided into the space between the introductory guide pieces  7   c  and then the space between guide pieces  7   b . The band B thus guided into the space between the guide pieces  7   b  is retained by the introductory guide pieces  7   c  between which the space is smaller than that between the guide pieces  7   b . Hence, the band B does not move upward from the band guide  7 .  
         [0062]    Even when the band guide  7  is drawn out to the maximum from the main body  1  as illustrated in FIG. 1, the band guide  7  has a part, e.g. one-fifth to one-sixth of its length, supported by the support mechanism provided in the main body  1 . Further, when the band guide  7  is drawn out to the maximum as described above, each retainer member  10  is in contact with the corresponding horizontal piece  7   d  and retains it.  
         [0063]    In the leading end of the band guide  7 , a directing piece  16  is provided and has a leading end which slops upward for conducting the band B, drawn from the band guide  7 , upward.  
         [0064]    The main body  1  thus incorporating the band guide  7  as described above is provided with four wheels  17  for moving the main body  1 . The support mechanism supports the band guide  7  in a position above the ground contact face of the wheels  17 . In other words, when the band guide  7  is drawn out, the band guide  7  is positioned above the ground or the floor. More specifically, the band guide  7  drawn out from the main body  1  is designed to maintain a position at which the band guide  7  is inserted between the bottom plate  53  and the top plate  51  of the pallet  50 . All of the dimensions and others of the pallet are defined by Japanese Industrial Standards, so that the position of the band guide is determined in correspondence with the defined dimensions.  
         [0065]    Next, the operation in the first embodiment will be explained.  
         [0066]    First, the band guide  7  is drawn out to the maximum from the main body  1  by hand and the stop mechanism S is operated for positioning the band guide  7 . Then, the main body  1  provided with the wheels  17  is moved to a site of an article w resting on a pallet  50 , and the vertical table  3  on the main body  1  is aligned with the article w. In this event, the band guide  7  is inserted into the space between a bottom plate  53  and a top plate  51  of the pallet  50 .  
         [0067]    At this point, the band feeding mechanism provided in the main body  1  is operated to draw a band B from the reel unit  2 . The band B having been drawn from the reel unit  2  is guided via the stationary guide  4  and the arcuate guide  5  into the band guide  7 . The band B thus guided into the band guide  7  passes through the band guide  7 , then through the inside of the pallet  50 , and is then guided by the directing piece  16  to be pushed out upward to the length required for tying.  
         [0068]    As described above, since the band B is pushed out upward by the directing piece  16 , a following band overlies the preceding band. Hence, the band is prevented from being tangled.  
         [0069]    After the band B is thus guided from the band guide  7 , the leading end of the band B is pinched for the band B to wind around the article w, and is then inserted into the band bonding mechanism.  
         [0070]    After the leading end of the band B is thus inserted into the band bonding mechanism, the band tightening mechanism  60  tightens the band B. After that, the bonding and the cutting processes are performed in the conventional baling machine manner.  
         [0071]    As described above, the main body  1  includes the wheels  17 . Hence, it is possible to move the main body  1  to the site of the article w resting on the pallet  50  for tying them with the band. In other words, to tie the article w with the band, the main body  1  can be brought close to the article w resting on the pallet  50  in a fixed place on the floor.  
         [0072]    Further, after the main body  1  is moved to the site where the article w resting on the pallet  50  is placed as explained above, the vertical table  3  on the main body  1  is aligned with the article w. When the vertical table  3  on the main body  1  is aligned with the article w, there is no need for the complicated operation of a forklift truck, resulting in improvement in workability.  
         [0073]    In a second embodiment as illustrated in FIGS.  6  to  8 , a pulley is used to move the band guide  7  into and out of the main body  1 . Specifically, a guide member  18  which is the support mechanism holds the band guide  7  allowing it to slide, and pins  19 ,  20  are respectively provided on the opposite sides at the back and front ends of the band guide  7 . A wire  25  is extended between the pins  19  and  20  via a plurality of pulleys  21  to  24 .  
         [0074]    The wire  25  is extended from the pin  19 , which is provided at the leading end of the band guide  7 , to the first pulley  21  provided at the rear of the band guide  7 , and then is changed in direction at the first pulley  21  so as to be guided upward to wind onto the driving pulley  22 . Then, the wire  25  having wound onto the driving pulley  22  is guided downward and changed in direction at the second pulley  23 , and then guided to the third pulley  24  provided toward the leading end of the band guide  7  to wind onto the third pulley  24 . Then, the wire  25  is turned around at the third pulley  24  so that the other end of the wire  25  is locked at the pin  20 .  
         [0075]    A handle  26  is provided to the driving pulley  22  and is turned by hand to rotate the driving pulley  22 .  
         [0076]    In FIGS. 6 and 7, a scale  27  is provided for measuring the amount of movement of an indicator  28  which is secured on the wire  25 , namely the amount of travel of the band guide  7 .  
         [0077]    In the event illustrated in FIG. 8, the handle  26  is turned to rotate the driving pulley  22  to pull the wire  25  in the direction indicated by the arrow in FIG. 8, whereupon the band guide  7  is drawn out forward. On the other hand, when the handle  26  is turned in the opposite direction to the above, the band guide  7  is retracted. The amount of travel of the band guide  7  can be measured by the amount of relative movement of the indicator  28  to the scale  27 .  
         [0078]    A third embodiment illustrated in FIGS. 9 and 10 employs a traction mechanism instead of the handle  26  employed in the second embodiment, and the remaining configuration is similar to that in the second embodiment.  
         [0079]    In the following description, the components equivalent to those in the second embodiment are designated by the same reference numerals.  
         [0080]    Pulleys  29 ,  30  are respectively provided above a first pulley  21  and a second pulley  23 . Wires  25  respectively turn in a downward direction at the pulleys  29 ,  30  and grips  31 ,  32  are respectively suspended at the leading ends of the wires  25 . One-way clutches  33 ,  34  are respectively provided between the grips  31 ,  32  and the pulleys  29 ,  30 . Upon pulling and then releasing the grips  31 ,  32 , the one-way clutches  33 ,  34  work to maintain the pulling position. When the one-way clutches  33 ,  34  are disengaged, the wires  25  can move back in the opposite direction.  
         [0081]    Hence, when one of the grips  31  and  32  is pulled, the band guide  7  moves in proportion to the amount of pulling of the grip  31  or  32 .  
         [0082]    A fourth embodiment illustrated in FIG. 11 is similar to the second and third embodiments in that the guide member  18  supports the band guide  7  allowing it to move.  
         [0083]    The fourth embodiment differs, however, in that the band guide  7  is moved by a rotor  36  which has a large frictional force and is provided in an electric motor  35 . Further, the fourth embodiment includes sensors  37 ,  38  for detecting the amount of travel of the band guide  7 .  
         [0084]    A fifth embodiment illustrated in FIGS. 12 and 13 employs a rack-and-pinion mechanism instead of the rotor  36  in the fourth embodiment. A rack  39  is provided on a side face of the band guide  7  and a pinion  40  is provided on the rotating shaft of the electric motor  35 .  
         [0085]    In the fifth embodiment, a rail  41  is provided on a side face of the band guide  7  and engages with wheels  42  provided in the main body  1 . Such rail  41  and wheels  42  constitute the support mechanism of the present invention.  
         [0086]    The remaining configuration is similar to that of the fourth embodiment.  
         [0087]    A sixth embodiment illustrated in FIG. 14 employs a screw shaft  43  instead of the rack-and-pinion mechanism of the fifth embodiment.  
         [0088]    A seventh embodiment illustrated in FIG. 15 employs a hydraulic cylinder  44  instead of the screw shaft  43 .  
         [0089]    [0089]FIG. 16 illustrates the specific structure of the band tightening mechanism  60  in FIG. 2.  
         [0090]    From the position indicated by the arrow in FIG. 16, a band B fed from the reel unit  2  is inserted between a feed roller  61  and an auxiliary roller  62 . Upon the entrance of the leading end of the band B between the feed roller  61  and the auxiliary roller  62 , a solenoid (not shown) is triggered to move the auxiliary roller  62  toward the feed roller  61 . The auxiliary roller  62  is moved toward the feed roller  61  to hold the band B between them, after which the feed roller  61  rotates. The rotation of the feed roller  61  carries the band B, inserted between the feed roller  61  and the auxiliary roller  62 , toward a curve guide  63 .  
         [0091]    The band B having been carried by the feed roller  61  so as to pass along the curve guide  63  is inserted between a tension roller  64  and an auxiliary tension roller  65  which are provided to give a strong tightening process. The band B is further inserted between the tension roller  64  and a tension plate  66 .  
         [0092]    Subsequently, the band B having passed between the tension roller  64  and the tension plate  66  as sent by the feed roller  61 , is directed along the linear guide  67 . The band B then passes between a return roller  68  and an auxiliary roller  69  which are provided at the midpoint in the linear guide  67 . The return roller  68  is provided for rewinding the band, as will be described later.  
         [0093]    The band B having passed between the return roller  68  and the auxiliary roller  69  is sent along the vertical table  3  and is inserted into the band retainer mechanism (not shown). The band B having passed through the band retainer mechanism reaches the aforementioned stationary guide  4 . As described in the first embodiment, the band B having passed through the stationary guide  4  is sent to the band guide  7 . The band B is extended from the leading end of the band guide  7  to the length required for tying, after which the rotation of the feed roller  61  is stopped.  
         [0094]    After the band is sent in this way, as described in the operation of the first embodiment, the operator puts the band B over the article w and then inserts the leading end of the band B into the band bonding mechanism, whereupon a sensor on a band stopper (not shown) is turned on.  
         [0095]    Upon the turning on of the sensor of the band stopper, the auxiliary roller  69  moves toward the return roller  68 . The auxiliary roller  69  and the return roller  68  then catch the band B between them, and then the return roller  68  rotates. The rotation of the return roller  68  moves the band B back to the reel unit  2  to the extent of the excess length of the band B put over the article w. When the band B put over the article w comes into tight contact with the surface of the article w, the rotation of the return roller  68  is stopped.  
         [0096]    Next, a tension solenoid  70  is activated to pivot an auxiliary roller arm  72  about an axis pin  71  in the counterclockwise direction in FIG. 16. Upon the pivoting of the auxiliary roller arm  72 , the auxiliary tension roller  65  moves toward the tension roller  64  to press the band B firmly against the tension roller  64 . At this point, the rotation of an output shaft of a motor  73  serving as the power source is transferred to the tension roller  64  to rotate it in the counterclockwise direction in FIG. 16. The rotation of the tension roller  64  firmly tightens the band B, which is held between the tension roller  64  and the auxiliary tension roller  65 , toward the reel unit  2 .  
         [0097]    The rotation of the output shaft of the motor  73  is transferred through a powder clutch  74  to the tension roller  64 . The following is a description of the configuration of the powder clutch  74 .  
         [0098]    As illustrated in the half sectional view of FIG. 17, a rotor  77  of the powder clutch  74  is coupled through a belt  76  to the output shaft of the motor  73 . By coupling through the belt  76 , the rotation of the output shaft of the motor  73  is transferred to the rotor  77 . The tension roller  64  is coupled to a shaft  75  of the powder clutch  74 . The rotor  77  supports the shaft  75  from outside through bearings  78 . A base body  84  of the powder clutch  74  supports the rotor  77  from outside through bearings  79 . Briefly, the shaft  75  and the rotor  77  are configured so as to be concentric.  
         [0099]    The rotor  77  is an input member of the present invention and the shaft  75  is an output member of the present invention.  
         [0100]    As illustrated in FIG. 17, a ring  80  is mounted on the shaft  75  and between the shaft  75  and the rotor  77 , and the periphery of the ring  80  is covered with a magnetic powder material  81 . The base body  84  is situated on the outer periphery of the magnetic powder material  81 , and includes a coil  82 . Upon the passage of an excitation current through a lead wire  83  connected to the coil  82 , a magnetic field is generated around the coil  82 . The magnetic powder material  81  bonds together firmly due to the generated magnetic field. The bonding of the magnetic powder material  81  causes fixation between the rotor  77  and the ring  80  mounted on the shaft  75 .  
         [0101]    As the excitation current passing through the coil  82  is increased, a force of the magnetic field generated around the coil  82  increases. As a force of the magnetic field increases, a strength of fixation between the shaft  75  and the rotor  77  increases to link the rotor  77  with the shaft  75 , thus torque of the rotor  77  is transferred directly to the shaft  75 . Briefly, as the excitation current passing through the coil  82  is increased, the torque transferred from the rotor  77  to the shaft  75  is increased.  
         [0102]    On the other hand, as the excitation current passing through the coil  82  is decreased, a force of the magnetic field generated around the coil  82  decreases. As a force of the magnetic field decreases, a strength of the fixation between the rotor  77  and the shaft  75  decreases. This results in transferring only part of torque of the rotor  77  to the shaft  75 . In other words, when the excitation current passing through the coil  82  is decreased, the rotor  77  and the shaft  75  are disengaged, resulting in a decrease in the torque transferred from the rotor  77  to the shaft  75 .  
         [0103]    In this way, it is possible to vary the excitation current passing through the coil  82  to change a strength of the fixation between the rotor  77  and the shaft  75  for controlling a magnitude of the torque transferred from the rotor  77  to the shaft  75 . That is to say, the band tightening mechanism  60  can vary the torque transferred from the rotor  77  to the shaft  75  in accordance with the amount of excitation current passing through the coil  82  of the powder clutch  74 , to control a force of tightening the band B.  
         [0104]    Explanation of Codes  
         [0105]    [0105] 1  MAIN BODY  
         [0106]    [0106] 3  VERTICAL TABLE  
         [0107]    [0107] 7  BAND GUIDE  
         [0108]    [0108] 17  WHEELS  
         [0109]    [0109] 60  BAND TIGHTENING MECHANISM  
         [0110]    [0110] 64  TENSION ROLLER  
         [0111]    [0111] 73  MOTOR  
         [0112]    [0112] 74  POWDER CLUTCH  
         [0113]    [0113] 75  SHAFT (OUTPUT MEMBER)  
         [0114]    [0114] 77  ROTOR (INPUT MEMBER)