Patent Publication Number: US-6655117-B2

Title: Arch type strapping machine

Description:
BACKGROUND OF THE INVENTION 
     In a conventional arch type strapping machine, a strapping band is fed to a band guide in an arch member to wind the band around an article to be strapped, and the strapping band is cut and bonded to form a loop, whereby the article is strapped. Such arch type strapping machine is provided with a sealing mechanism for the strapping band. The sealing mechanism comprises a first gripper (hereinbelow, referred to as a right gripper) for fixing a top end of the strapping band fed into the band guide, a second gripper (hereinbelow, referred to as a left gripper) for fixing a rear portion of the strapping band after the band has been pulled back to be tightened and a compression head for compressing and bonding (in many cases, melt-bonding) the top end and the rear portion of the strapping band and cutting the rear portion of the band. The right gripper, the left gripper and the compression head are operated by driving cams attached to a shaft for sealing which is rotated and driven by a motor for sealing. 
     In the conventional arch type strapping machine, a step for pulling back the strapping band at a high speed and a step for tightening the band at a high torque intervene between the operation of the right gripper and the operation of the left gripper. Accordingly, in the operation of the above-mentioned sealing mechanism, it is necessary that the rotation of the shaft for sealing is once stopped after the right gripper has been operated, and the shaft for sealing is again rotated to cause the operations of the left gripper and the compression head after the step for pulling back the band at a high speed and the step for tightening the band at a high torque have been finished. Accordingly, it is difficult to rotate the shaft for sealing at a high speed whereby a demand of shortening the cycle of strapping can not be satisfied sufficiently. Further, the service life of the sealing mechanism is short because the number of times of temporary stop of the driving system in the sealing mechanism is many. 
     Further, in a conventional arch type strapping machine, an article is strapped by performing a band feeding step for feeding a strapping band into a band guide in an arch member, a first tightening step for winding the strapping band around an article to be strapped by returning quickly the band fed into the band guide, a second tightening step for tightening strongly the strapping band wound around the article by returning the band, and a step for bonding (in many cases, melt-bonding) a rear portion and a top end of the band wound around the article to be strapped and cutting the band. The band feeding step and the first and second tightening steps are carried out by a driving mechanism comprising a plurality of rollers for running and tightening the strapping band. 
     Such driving mechanism for the strapping band makes the size of the arch type strapping machine large because a plurality of driving rollers are used, e.g., a driving roller for performing the band feeding step as well as the first tightening step and a driving roller for performing the second tightening step being provided separately. Accordingly, this is contrary to a demand of reducing the size of the arch type strapping machine. 
     Further, in a conventional arch type strapping machine, an article is strapped with a strapping band in such a manner that the strapping band is fed into a groove formed in a band guide having a channel-like shape in cross section, an open side of which is pushed to an inner surface of the arch member; the strapping band fed into the band guide is wound around the article to be strapped by returning the band at a high speed; the strapping band wound around the article is tightened by pulling it back, and the cutting of a rear portion of the band and bonding (melt-bonding) of the rear portion to an top end of the band is conducted. The returning of the strapping band at a high speed is conducted immediately after the state that the strapping band leaves entirely or partly from the band guide, such state being obtainable by opening forcibly the band guide in a direction departing from the inner surface of the arch member with which the band guide is brought into contact. 
     The width or the height (in particular, the height) of the groove of the band guide is formed to be relatively small so that the strapping band can be certainly passed without causing the bending of a top end of the band. In the operation for opening the band guide, there is a possibility that the strapping band follows the movement of the band guide due to a frictional force between an inner surface of the groove and the strapping band, and the band remains in the groove. If the strapping band is tightened at a high speed in the state that the strapping band remains in the groove, an unusual deformation is caused instantaneously in the band guide at the time of leaving the strapping band, whereby the band guide is damaged. 
     Further, in a conventional arch type strapping machine, the strapping band is rewound from a band roll fitted to a band reel which is attached to an outer side of the arch type strapping machine, to be stored temporarily in a band accommodation chamber in the strapping machine. Then, the strapping band in the band accommodation chamber is successively fed into the band guide. 
     In many cases, the band reel comprises a supporting shaft having an end supported by the main body of the strapping machine, a reed portion attached to the supporting shaft so that at least a part (in many cases, a rear side plate) is removable from the supporting shaft, the reel portion being adapted to mount the band roll for the strapping band, and a nob attached to a rear end of the supporting shaft to fix the reel portion. When a used band roll mounted on the band reel is replaced by a new one, the nob and, for instance, the rear side plate are removed from the supporting shaft; the core member of the used band roll is removed from the reel portion; a new band roll is attached to a reel portion, and then, the rear side plate and the nob are fixed again to the supporting shaft. 
     In many cases, the structure for fitting the nob to the supporting shaft comprises a male screw formed in a rear end (the free end) of the supporting shaft and a female screw formed in the nob so that the nob can be fitted to the supporting shaft by rotating it several times of turn. Accordingly, in the replacement of the band roll, it is necessary to turn back the tightly fastened nob, and the nob is tightly fastened by rotating after new band roll is mounted. Accordingly, the working for replacing the band roll is troublesome. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an arch type strapping machine having a sealing mechanism for cutting and bonding a strapping band fed into the band guide of the strapping machine, which is capable of achieving the speed-up of strapping operations and having a long service life. 
     Further, it is an object of the present invention to provide an arch type strapping machine having a strapping band driving mechanism for feeding the strapping band into the band guide and pulling back the band, which is suitable for reducing the size of the strapping machine. 
     Further, it is an object of the present invention to provide an arch type strapping machine having a band reel adapted to mount a band roll on which the strapping band fed into the band guide is wound, which permits the fitting and the removal of a nob easily. 
     Further, it is an object of the present invention to provide an arch type strapping machine having a band driving-out device which can provide a state that the strapping band leaves certainly from a groove for receiving the band at the time of opening the band guide without losing a smooth opening operation of the band guide. 
     In accordance with an aspect of the present invention, there is provided an arch type strapping machine having a sealing mechanism which comprises a right gripper for fixing a top end of a strapping band fed into a band guide of the arch type strapping machine; a left gripper for fixing a rear portion of the strapping band after the strapping band has been wound around an article to be strapped and tightened; a compression head for compressing and bonding the top end and the rear portion of the strapping band and cutting the rear portion of the band, and a driving means for operating the right gripper, the left gripper and the compression head, said arch type strapping machine being characterized in that the driving means of the sealing mechanism comprises a first driving section for operating the right gripper and a second driving section for operating the left gripper and the compression head, wherein the second driving section comprises a motor for sealing, a shaft for sealing rotated by the motor, a cam for fixing attached to the shaft for sealing to operate the left gripper, and a cam for bonding to operate the compression head. 
     In accordance with another aspect of the present invention, there is provided an arch type strapping machine having a strapping band driving mechanism which performs a band feeding step for feeding a strapping band into a band guide of the arch type strapping machine, a first tightening step for winding the strapping band around an article to be strapped by returning quickly the strapping band fed into the band guide and a second tightening step for tightening strongly the strapping band around the article by pulling back the strapping band, the arch type strapping machine being characterized in that the strapping band driving mechanism comprises a d.c. motor capable of rotating in a positive direction of feeding and in a reverse direction of returning; a band driving roller attached to an end of an output shaft for band-running of the d.c. motor and a motor for driving a shaft for sealing, connected to the output shaft via an electromagnetic clutch which is attached to the other end of the output shaft of the d.c. motor, wherein the band feeding step is performed by the rotation of the band driving roller caused by the rotation in a direction of feeding of the d.c. motor; the first tightening step is performed by the rotation of the band driving roller which is caused by the rotation in a direction of returning of the d.c. motor, and the second tightening step is performed by the rotation of the band driving roller which is caused by an output of rotation from the motor for driving the shaft for sealing via the electromagnetic clutch. 
     The output of rotation from the motor fro driving the shaft for sealing, which is transmitted by connecting the electromagnetic clutch is in many cases, an output of a low speed/high torque rotation. 
     In accordance with another aspect of the present invention, there is provided an arch type strapping machine having a band driving-out device adapted to discharge a strapping band from a band guide when the band guide disposed in an arch member of the arch type strapping machine is opened whereby the strapping band is prevented from remaining in a band groove, the arch type strapping machine being characterized in that the band driving-out device comprises a push pin inserted movably in a through hole formed in a rear portion of the band guide, a pin stopper disposed to oppose a head portion of the push pin, and a spring member disposed between the rear portion of the band guide and the head portion of the push pin so as to push the head portion of the push pin to bring it into contact with the pin stopper. 
     In accordance with another aspect of the present invention, there is provided an arch type strapping machine having a band reel for a strapping band, the arch type strapping machine being characterized in that the band reel for a strapping band comprises a supporting shaft having an end supported by the main body of the strapping machine, a reel portion attached to the supporting shaft, which is adapted to mount a band roll on which a strapping band fed to a band guide in an arch member of the arch type strapping machine is wound, and a nob attached to a rear end of the supporting shaft to fix the reel portion, wherein the nob has a cylindrical portion fitted to an outer periphery of a rear end of the supporting shaft; the cylindrical portion is provided with a guide groove extending spirally from its front side to its rear side; a recess is formed in the innermost portion of the guide groove, and a pin capable of passing relatively the guide groove to fit to the recess is provided in a rear end portion of the supporting shaft. 
     The supporting shaft may be such one supported rotatably by the main body of the strapping machine. In this specification, the side of the supporting shaft supported by the main body of the strapping machine is referred to as a front side. The rear end of the supporting shaft is free. The nob for fixing the reel portion may be a cap. The recess may be a groove. 
    
    
     BRIEF DESRIPTION OF THE DRAWINGS 
     In drawings: 
     FIG. 1 is a front view showing diagrammatically an inner structure of the arch type strapping machine with a sealing mechanism according to the present invention; 
     FIG. 2 is an enlarged front view partly cross-sectioned showing a roller unit; 
     FIG. 3 is an enlarged front view partly cross-sectioned showing the sealing mechanism; 
     FIG. 4 is a front view showing the structure for operating a right gripper; 
     FIG. 5 is a front view showing the structure for operating a left gripper; 
     FIG. 6 is a plan view showing the structure for driving the roller unit and the sealing mechanism; 
     FIG. 7 is a side view showing the structure for driving the roller unit and the sealing mechanism; 
     FIG. 8 is a front view showing the structure for operating a seal anvil and a heater; 
     FIG. 9 is a front view showing diagrammatically a band guide of the arch type strapping machine with a band driving-out device according to the present invention; 
     FIG. 10 is a plan view partly cross-sectioned showing an upper supporting device in detail; 
     FIG. 11 is a plan view showing a pushing type solenoid plunger for opening the band guide; 
     FIG. 12 is a plan view partly cross-sectioned showing the band driving-out device in detail wherein a state before opening the band guide is shown; 
     FIG. 13 is a plan view partly cross-sectioned of the band driving-out device wherein a state after opening the band guide is shown; 
     FIG. 14 is a vertically cross-sectional view showing the structure of a band reel; 
     FIG. 15 is a diagram showing the cylindrical portion of a nob with a guide groove in an developed state; and 
     FIG. 16 is a cross-sectional view showing a state of engagement of pins formed in a supporting shaft. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following, preferred embodiments of the arch type strapping machine of the present invention will be described with reference to the drawings. 
     FIG. 1 is a front view showing diagrammatically an inner structure of the arch type strapping machine having a sealing mechanism for a strapping band according to the present invention; FIG. 2 is an enlarged front view showing a roller unit, and FIG. 3 is an enlarged front view showing the sealing mechanism. 
     An arch type strapping machine  1  comprises a main body  5  in which a band accommodation chamber  3  is formed, an arch member  9  provided on the main body  5  so as to accommodate a band guide  7 , a band reel  13  attached to an outer side of the main body  5 , on which a band roll (not shown) for a strapping band  11  is mounted, a roller unit  15  disposed in the main body  5  and adapted to feed forward and tighten the strapping band  11 , and a sealing mechanism  17  for the strapping band which is disposed in the main body  5  and which cuts and melt-bonds the strapping band  11 . The strapping band  11  is rewound from the band reel  13  due to the rotation of a feeding/driving roller  19  in a direction of arrow mark A (i.e., a clockwise direction) in the roller unit  15 , to be supplied to the band accommodation chamber  3 . Then, the strapping band  11  in the band accommodation chamber  3  is fed to the band guide  7  by means of a strapping band driving mechanism  21  in the roller unit  15 . 
     A pair of winding rollers  23  are provided at front and rear sides of the feeding/driving roller  19 . The strapping band  11  is fed in a snaky movement between each of the winding rollers  23  and the feeding/driving roller  19 , passed on a guide roller  25 , and supplied to the band accommodation chamber  3 . The strapping band driving mechanism  21  comprises a band driving roller  27 , a band-running rocker roller  29  disposed at a specified position above the band driving roller  27  to hold the strapping band  11  in association with the band driving roller  27 , and a second tightening rocker roller  33  disposed at a specified position below the band driving roller  27  wherein the second tightening rocker roller  33  is moved so as to hold the strapping band  11  in association with the band driving roller  27  when a solenoid plunger for secondarily tightening  31  is operated. In a band feeding step, the strapping band  11 , which is extended to the sealing mechanism  17  via the guide roller  25 , a guide  35 , the band driving roller  27  and the band-running rocker roller  29 , is introduced into the band guide  7  through a center guide  37  by the rotation of the band driving roller  27  in a counter clockwise direction (indicated by an arrow mark B) so that a top end of the strapping band  11  is returned to the sealing mechanism  17 . When a proximity switch  39  detects that the top end of the strapping band  11  has reached the position of the sealing mechanism  17 , the band feeding step is finished, and the rotation of the band driving roller  27  is stopped. The top end of the strapping band  11  returned to the position of the sealing mechanism  17  through the band guide  7  is clamped by a right gripper or a top end gripper  45  (a first gripper) ascended according to a rotating or swinging movement of an L-like lever  43  which is caused by the operation of a solenoid plunger for fixing  41  (a first driving section) and a seal anvil or an iron bed for sealing  47  so that the top end of the strapping band  11  is fixed as shown in FIG. 3 (see FIG. 4 which is a front view showing the structure for operating the right gripper  45 . FIG. 4 shows a state that the right gripper  45  descends whereas FIG. 3 shows a state that the right gripper  45  ascends). A solenoid plunger  51  for opening the band guide, an operating shaft  53  and a link  55  constitute a first band guide driving unit. The center guide  37  is unified with the band guide  7  so as not to cause any deflection in the passage for the band. 
     At substantially the same time of fixing the top end of the strapping band  11 , pushing type solenoid plungers  49  for opening the band guide (each constituting a second band guide driving unit) are operated, and the links  55  are operated by the rotation of the operating shaft  53  due to the operation of the solenoid plunger  51  for opening the band guide, whereby the entirety of the band guide  7  including the center guide  37  is moved to be opened in a front direction in FIG.  1 . As a result, the strapping band  11  comes off from the band guide  7  by bringing the band guide  7  apart from the arch member  9  (more specifically, an arch plate as an element at one side of the arch member  9 ). 
     Subsequent to the opening operation of the band guide  7 , the strapping band  11  is pulled back at a high speed by a high speed rotation of the band driving roller  27  in a clockwise direction (indicated by an arrow mark C) so that the strapping band  11  is wound around an article to be strapped  57  (a first tightening step). As soon as the first tightening step is finished, the band driving roller  27  is rotated at a low speed and a high torque in a clockwise direction, and the second tightening rocker roller  33  is moved in a direction coming to contact with the band driving roller  27  due to the operation of the solenoid plunger for secondary tightening  31  so that the strapping band  11  is strongly held between the second tightening rocker roller  33  and the band driving roller  27 . Accordingly, the strapping band  11  wound around the article to be strapped  57  is strongly pulled back for tightening (a second tightening step). A rotating type pulse generator (not shown) is mounted on the band-running rocker roller  29 . The absence of an output of rotating pulses from the rotating type pulse generator indicates the cease of the rotation of the band-running rocker roller  29 . Therefore, the completion of the first tightening step can be confirmed by the detection of the absence of the rotation pulses. 
     In the completion of the second tightening step, a shaft for sealing  59  in the sealing mechanism  17 , which extends in a direction perpendicular to the arch member  9 , is rotated once at a constant speed in a clockwise direction (indicated by an arrow mark D) in FIG.  3 . The sealing mechanism  17  has the right gripper  45 , a left gripper or a rear side gripper  61  (a second gripper) and a compression head or a press-cutting head  63 . The left gripper  61  and the compression head  63  are operated by the rotation of a cam for fixing  65  and a cam for bonding  67  which are attached to the shaft for sealing  59  (see FIG. 5 showing the structure for operating the left gripper  61 ). Immediately after the initiation of rotation of the shaft for sealing  59  from its neutral position, the left gripper  61  is moved upward by a swing lever  69  pushed upward by a pushing force of the cam for fixing  65 , whereby a rear portion of the strapping band  11  is held and fixed between the left gripper  61  and the seal anvil  47 . An upper end of the left gripper  61  has a rough surface, and a lower surface of the seal anvil  47  corresponding to the left gripper  61  has a flat surface, whereby a possibility of damaging or cutting the strapping band  11  in a case that the rear portion of the strongly stretched strapping band  11  is held and fixed, can be eliminated. 
     A heater  71  is disposed at a position in height between the center guide  37  and the seal anvil  47 , or a position having a substantially the same level as an upper end of the center guide  37 . The heater  71  is moved forward to a position between the top end and the rear portion of the strapping band  11 . When the shaft for sealing  59  is further rotated, the compression head  63  is moved upward by a pushing force of the cam for bonding  67  so as to press the top end of the strapping band  11 , the heater  71  and the rear portion of the strapping band  11 , in an overlapping state, to the seal anvil  47 . Then, the compression head  63  cuts a rear portion of the strapping band  11 , and at the same time, it melts the top end and the rear portion of the strapping band  11 . 
     When the shaft for sealing  59  is rotated further, the compression head  63  is slightly descended along the cam surface of the cam for bonding  67  by a pulling force of a tension coil spring  73 , and the heater  71  is retracted to be withdrawn between the top end and the rear portion of the strapping band  11 . When the shaft for sealing  59  is rotated further, the compression head  63  is ascended again so that the molten top end and rear portion of the strapping band  11  are pressed and melt-bonded in association with the seal anvil  47 . When the shaft for sealing  59  is rotated further, the right gripper  45 , the left gripper  61  (which is pulled in a lower direction by a tension coil spring  75 ) and the compression head  63  are descended; the seal anvil  47  is retracted, and the shaft for sealing  59  is further rotated to a position of 360° rotation (the neutral portion) at which the shaft for sealing  59  is stopped (see FIG. 8 showing a state that the seal anvil  47  is at an advanced position when the shaft for sealing  59  is returned to the neutral position). In FIG. 8, reference numeral  77  designates a position determining device for the shaft for sealing  59 . The position determining device  77  comprises a disc  78  attached to the shaft for sealing  59  and a swing arm  83  having a roller  79  in contact with the disc  78  at its intermediate portion and an end connected to a supporting shaft  81 . The swing arm  83  is connected with a tension spring (not shown) which urges the swing arm  83  in such a direction that the roller  79  is pushed to the disc  78 . When the shaft for sealing  59  is returned to the neutral position, the roller  79  is fitted to a recessed portion (not shown) formed in a portion of the disc  78  by a pulling force of the spring, whereby the shaft for sealing  59  can correctly be stopped at the neutral position. 
     The article  57  after having been strapped is discharged from the arch type strapping machine  1 . Then, an electric current fed to the push type solenoid plunger  49  for opening the band guide and the solenoid plunger  51  for opening the band guide is interrupted, whereby the band guide  7  including the center guide  37  is restored to a state that it is pushed to the arch member  9 . 
     The driving mechanism for the roller unit  15  and the sealing mechanism  17  will be described with reference to FIG. 6 as a plan view and FIG. 7 as a side view. 
     The band driving roller  27  is attached to an end of the output shaft  87  of a d.c. motor  85 . An electromagnetic friction clutch  91  with a pulley  89  is provided on the other end of the output shaft  87 . A tooth clutch  95  having a pulley  93  is provided at a rear end of the shaft for sealing  59  which is rotated by a motor  97 . The band feeding/driving roller  19  is connected via an electromagnetic clutch  101  to an end of the output shaft  99  of the motor  97  for driving the shaft for sealing. A reduction unit  105  having a pulley  103  is provided at the other end of the output shaft  99 . A single driving belt  107  is wound around the pulley  89 , the pulley  93  and the pulley  103 . In the band feeding step, the strapping band  11  is driven by a high speed rotation of band driving roller  27  which is caused by a high speed rotation of the d.c. motor  85  in a counterclockwise direction, and in the first tightening step, the strapping band  11  is driven by a high speed rotation of band driving roller  27  which is caused by a high speed rotation of the d.c. motor  85  in a clockwise direction. In the second tightening step, the electromagnetic friction clutch  91  is connected to the output shaft  87  of the d.c. motor  85  so that a rotating force of low speed/high torque of the reduction unit  105  connected to the motor  97  is transmitted to the output shaft  87 , whereby the strapping band  11  is strongly pulled back by the rotation of low speed/high torque of the band driving roller  27 . The adjustment of the second tightening force is conducted by changing a voltage applied to the electromagnetic friction clutch  91 . In the completion of the second tightening step, the tooth clutch  95  is connected to the shaft for sealing  59  so that the shaft for sealing  59  is rotated by the motor  97  for driving the shaft for sealing  59 . Then, the left gripper  61  is raised to press the strapping band  11 . Then, the electromagnetic friction clutch  91  is disconnected, and subsequent to this, the compression head  63  is operated. When the shaft for sealing  59  is rotated continuously by 360°, a sealing step is finished. In this case, when the fact that the shaft for sealing  59  is returned to the neutral position after the rotation of 360°, the tooth clutch  95  is disconnected, and the rotation of the motor  97  for driving the shaft for sealing is stopped. 
     When a band quantity sensor  109  detects that the quantity of the strapping band  11  in the band accommodation chamber  3  decreases to a predetermined level, the electromagnetic clutch  101  is connected to the output shaft  99  of the motor  97  for driving the shaft for sealing  59  so that the band feeding/driving roller  19  is rotated by a driving force from the motor  97  for driving the shaft for sealing  59 , and the strapping band  11  is rewound from the band reel  13  so as to supply the band into the band accommodation chamber  3 . 
     The mechanism for operating the seal anvil  47  and the heater  71  will be described with reference to FIG.  8  and FIG.  6 . 
     The heater  71  is attached to a heater supporting member  111  which is attached in a manner capable of sliding to a supporting shaft  81  which is extended in a direction of front and back, i.e., a direction of moving the heater  71  (FIG.  6 ). Further, the seal anvil  47  is attached to a supporting member  113  which is attached in a manner capable of sliding to the supporting shaft  81  at a front side with respect to the heater supporting member  111  (FIG.  6 ). A tension coil spring  117  is extended between the heater supporting member  111  and a supporting plate  115  of the arch type strapping machine  1  so that the heater supporting member  111 , hence, the heater  71  is always pulled in a front direction. The supporting member  113  is attached in a manner capable of sliding to a pressing shaft  119 , and a compression coil spring  121  is located between a rear end of the pressing shaft  119  and the supporting member  113 , whereby the supporting member  113 , hence, the seal anvil  47  is always pushed in a front direction. A connecting rod  123  is attached to the heater supporting member  111 . The connecting rod  123  is inserted in a manner capable of sliding in a hole formed in the supporting member  113 , and has a head for pulling  125  at its top end. The heater supporting member  111  is adapted to move in a direction of front and back along a cam surface which is formed at a rear end of a cylindrical cam  127  attached to the shaft for sealing  59 . FIG. 8 shows a state before the initiation of rotation of the shaft for sealing wherein the seal anvil  47  is advanced and the heater  71  is retracted. In such state, when the shaft for sealing  59  is rotated at substantially the same time of the completion of the second tightening step, the left gripper  61  is raised, and subsequent to this, the heater supporting member  111  is moved in a front direction along the cam surface of the cylindrical cam  127  by a pulling force of the tension coil spring  117 , and then, the heater  71  is moved between the rear portion and the top end of the strapping band  11 . The seal anvil  47  is prohibited to move forward beyond the position as indicated in FIG.  8 . 
     When the shaft for sealing  59  is rotated further, the heater supporting member  111  is moved in a rear direction by the cam surface of the cylindrical cam  127 , whereby the heater  71  is also retracted. However, the seal anvil  47  is remained at the advanced position. When the heater supporting member  111  is retracted further by the pushing force of the cam surface of the cylindrical cam  127  with the rotation of the shaft for sealing  59 , the supporting member  113  is moved in a rear direction by a pulling force of the connecting rod  123 , and therefore, the seal anvil  47  is moved backward. When the shaft for sealing  59  is rotated further, the heater supporting member  111  is moved forwardly along the cam surface of the cylindrical cam  127 , and the supporting member  113  is also moved forwardly by a pushing force of the compression coil spring  119 . Then, the seal anvil  47  and the heater  71  are restored to the state as shown in FIG. 8 by the rotation of 360° of the shaft for sealing  59 . 
     The cylindrical cam  127  has also a cam surface at its front end, which as soon as the initiation of the rotation of the shaft for sealing  59 , operates a vertically extending portion  129  of the L-like lever  43  to maintain the right gripper  45  at an elevated position (see FIG.  4 ), whereby an electric current to the solenoid plunger for fixing  41  is interrupted. Just before the completion of the rotation of 360° of the shaft for sealing  59 , the L-like lever  43  is rotated in a direction of raising along the cam surface formed at the front end of the cylindrical cam  127  by a pushing force of a spring  131  to return to the original position, and the right gripper  45  is lowered. 
     In the above-mentioned embodiment, the first driving section and the second driving section are respectively constructed so as to operate separately. The right gripper is operated by the first driving section, and then, the second driving section is operated. The second driving section comprises the motor for sealing, the shaft for sealing, and the cam for fixing and the cam for bonding which are attached to the shaft for sealing. The left gripper and the compression head are operated sequentially by the continuous rotation of 360° of the shaft for sealing which is caused by the motor for sealing. The source for driving the first driving section is generally separate from the motor for sealing as the source for driving the second driving section. The right gripper is not always necessary to be operated by the first driving section. The first driving section is to cause an initial operation of the right gripper. Another driving section may be provided to maintain the initial operation and may perform the subsequent operations for the right gripper. 
     In a case of opening forcibly the band guide, a cam is usually provided on the shaft for sealing so that the band guide is opened by the rotation of the shaft for sealing. However, the band guide has to be maintained in an opening state at least until the completion of the strapping band pulling step. Accordingly, it is necessary for the above-mentioned structure to stop once the shaft after the rotation of the shaft for sealing, and then, to rotate again the shaft. Therefore, in order to open forcibly the band guide, another driving section for the band guide may be provided separate from the second driving section. A solenoid plunger may be used for the first driving section and the driving section for the band guide. 
     Further, in the above-mentioned embodiment, the band driving roller is driven by the motor in order to perform directly the band feeding step, the first tightening step and the second tightening step. 
     In order to reduce the size of the arch type strapping machine, it is preferred to feed the strapping band into the band accommodation chamber by providing a band feeding/driving roller on one side of the output shaft of a motor via an electromagnetic clutch and providing a reduction unit on the other side of the output shaft wherein the band feeding/driving roller is rotated by the connection of the electromagnetic clutch, and to conduct the second tightening step by the rotation of the band driving roller due to a rotating force from the reduction unit. Further, it is effective to use the above-mentioned motor to operate the sealing mechanism (including a part of the sealing mechanism) for cutting a rear portion of the strapping band wound around an article to be strapped, and then, bond (or melt-bond) the rear portion to the top end of the strapping band. In many cases, the motor is to rotate the shaft for sealing to which a driving cam is attached. Or, the motor for driving the sealing mechanism may be used for a source for conducting the second tightening step so that an output of rotation of the motor is transmitted to the band driving roller. 
     Another embodiment of the present invention will be described with reference to FIGS. 9 to  11 . 
     FIG. 9 shows diagrammatically a band guide  7  of the arch type strapping machine  1  provided with band driving-out devices  239  for a strapping band according to the present invention; FIG. 10 is a plan view partly cross-sectioned showing an upper supporting device in detail, and FIG. 11 is a plan view partly cross-sectioned showing a pushing type solenoid plunger for opening the band guide. 
     The band guide  7  having a channel-like shape in cross section is arranged in a loop form along the arch member  9  of the arch type strapping machine  1 , and an upper central portion of the band guide  7  is supported by the upper supporting device  207 . The upper supporting device  207  comprises a movable supporting member  209  located at an upper central portion of the band guide  7 , a guide rod  215  attached to a first arch plate  211  (a front side arch plate) of the arch member  9  and a second arch plate  213  (a rear side arch plate) of the arch member  9  in its upper portion to extend horizontally or in parallel to a front/rear direction, i.e., in a width direction of the band guide  7  and to support the movable supporting member  209  in a manner capable of sliding, and a compression coil spring  217  wound on the guide rod  215  between the second arch plate  213  and the movable supporting member  209 . With this, the band guide  7  is in such a state that a side of the opening of a groove  219  of the channel-like band guide  7  is pressed to the first arch plate  211  by a spring action of the compression coil spring  217 . In this state, the strapping band  11  is movable in the groove  219 . When the band guide  7  is opened, the movable supporting member  209  is urged together with the band guide  7  in a rear direction, i.e., the band guide  7  being moved in a direction aparting from the first arch plate  211 , along the guide rod  215  against the spring action of the compression coil spring  217 . The groove  219  is preferably formed to be thin. Accordingly, a lower wall of the band guide  7  in FIG. 10 on which the band slips, is formed to be slightly thin so that the withdrawal of the band  11  can be smooth even when the band drags on the inner surface of the groove  219 . 
     Pushing type solenoid plungers  49  for opening the band guide are fixed to the first arch plate  211  at the second and third corner portions of the arch member  9  respectively. An operating portion  49   a  of each of the pushing type solenoid plungers  49  is attached to the band guide  7 . When the pushing type solenoid plungers  49  are operated wherein each of the operating portions  49   a  is moved in a direction of an arrow mark in FIG. 11, the band guide  7  is pulled by the operating portions  49   a  so that the band guide  7  is moved to be opened in a direction aparting from the first arch plate  211 . 
     In FIG. 9, a pair of return spring members  227  are provided at both sides of the band guide  7 . Each of the return spring members  227  is constituted by a stick  229  and a tension coil spring  231  connected to a lower end of the stick  229  wherein an upper end of the stick  229  is attached to the first arch plate  211  in a rotatable manner, and a lower end of the tension coil spring  231  is attached to an outer side of the band guide  7 . 
     Below the arch member  9 , the operating shaft  53  is disposed in a rotatable manner along a lower portion of the band guide  7 . The operating shaft  53  and the lower portion of the band guide  7  are connected by means of the link  55 . An end portion of the operating shaft  53  is connected to the solenoid plunger  51  for opening the band guide  7 . By the operation of the solenoid plunger  51 , the operating shaft  53  is rotated to open the band guide  7  via the link  55 . The lower portion of the band guide  7  is pushed by a spring (not shown) toward the first arch plate  211 . 
     Accordingly, when the pushing type solenoid plungers  49  and the solenoid plunger  51  are operated simultaneously, the band guide  7  is moved in its entirety to perform an opening operation in a direction aparting from the first arch plate  211 . The arch member  9  is provided with a pair of band driving-out devices  239  each of which prevents the strapping band  11  from following the movement of the band guide  7  and remaining in the groove  219  of the band guide  7  when the band guide  7  is subjected to the opening operation. 
     FIG. 12 is a plan view partly cross-sectioned of a band driving-out device in detail wherein a state before the opening of the band guide  7  is shown, and FIG. 13 shows a state after the opening of the band guide  7 . 
     Each of the band driving-out devices  239  is provided at lower corner portions of the arch member  9 , and comprises a pin stopper  241  made of a metallic plate, a push pin  245  having a head portion  243  at its rear end and a compression coil spring  247 . The pin stopper  241  has an integral body comprising a fixing portion  249  fixed to the first arch plate  211 , a portion  251  having a larger width than the band guide  7 , which extends from an end of the fixing portion  249  in a rear direction, i.e., in a width direction of the band guide  7  and a rear portion  255  which is contiguous to the other end (a rear end) of the portion  251  and which extends in parallel to the arch member  9  or the first and second arch plates  211 ,  213  to a position behind a rear portion  253  of the band guide  7 . 
     A through hole  257  is formed penetrating the rear portion  253  of the band guide  7  to reach the groove  219 . The push pin  254  is inserted in the through hole  257  from its top end side in a manner capable of sliding. The compression coil spring  247  is fitted to the push pin  245  so as to be interposed between a rear surface of the band guide  7  and the head portion  243  of the push pin  245 , whereby the head portion  243  of the push pin  245  is always pressed toward the rear portion  255  of the pin stopper  241  to be in contact with the rear portion  255 . Before the opening operation of the band guide  7 , the band guide  7  is pressed to the first arch plate  211  by the compression coil spring  247 , and the top end of the push pin  245  is around the top end side of the through hole  257  so as not to enter into the groove  219 . When the opening operation of the band guide  7  is started against the spring action of the compression coil spring  247 , the top end of the push pin  245  enters into the groove  219  and is advanced relatively to the position of the opening of the groove  219  in a state that the band guide  7  is fully opened. Accordingly, the strapping band  11  is driven out from the groove  219  by means of the push pin  245  even when the band  11  tends to follow the movement of the band guide  7 . Thus, the strapping band is in a state of being drawn entirely from the band guide  7  in the completion of the opening operation of the band guide  7 . 
     After the strapping band  11  has been pulled back at a high speed, followed by tightening strongly, cutting the rear portion and melt-bonding the rear portion to the top end, the feeding of electric current to the pushing type solenoid plungers  49  and the solenoid plunger  51  is stopped, whereby the band guide  7  is restored to be a state of being in contact with the first arch plate  211  by the spring actions of the compression coil spring  217  on the upper supporting device  207 , the return spring members  227 , the compression coil spring  247  of the band driving-out devices  239  and other springs. 
     In the above-mentioned embodiment of the present invention, the through hole is formed to penetrate the rear surface of the band guide to reach the groove. When the band guide is pressed to the inner surface of the first arch plate, namely, the head portion of the push pin is pressed to the pin stopper by the spring, the top end of the push pin does not enter into the groove, or is inserted slightly. Accordingly, there is little possibility that the movement of the strapping band in the groove of the band guide is hindered by the push pin. 
     When the band guide is operated to be opened by the spring action in a direction aparting from the inner surface of the first arch plate, i.e., in a direction that the opening of the groove is apart from the inner surface of the first arch plate in a state that the strapping band is supplied into the groove of the band guide, the top end of the push pin enters deeply into the groove so that the strapping band or a band portion which tends to follow the movement of the band guide, is driven out from the groove. Since the push pin is merely brought into contact with the pin stopper, namely, the push pin is capable of sliding with respect to the pin stopper, there is little possibility of causing a trouble in the opening operation of the band guide even when the band guide shakes in the opening operation to increase a frictional force between the push pin and the band guide. 
     The spring member in the band driving-out devices functions to bring the push pin into contact with the pin stopper when the band guide is returned to the original position. Further, this spring member provides generally a returning force or a substantial auxiliary returning force to the band guide. Usually, the spring member acts on the band guide to provide a pushing force or an auxiliary pushing force against the inner surface of the first arch plate. It is preferable that the spring force of the spring member is such an extent that a contact pressure between the head portion of the push pin and the pin stopper is not too excessive, and the push pin can smoothly slide toward the pin stopper when the band guide is operated for opening. By using the compression coil spring fitted around the push pin as the spring member, the structure of the band driving-out device can be simple. The band driving-out devices of the present invention are preferably located at such positions that the strapping band can follow a forcibly opening operation of the band guide, for example, at corner portions of the arch member or the band guide. 
     The pin stopper may be such one fixed to the arch member. However, the arch plate at the opposite side of the arch plate to which the band guide is pressed can be used as it is. 
     In the following, another embodiment of the present invention will be described with reference to the drawings. The general structure and the operation of the arch type strapping machine provided with a band reel for a strapping band of this embodiment are the same as the description based on FIGS. 1 to  8  concerning the first embodiment, and therefore, the description is omitted. 
     FIG. 14 is a vertically cross-sectional view showing the entire structure of a band reel  13  for a strapping band; FIG. 15 is a diagram in a developed state of a portion in which guide grooves are formed in a cylindrical portion of a nob, wherein the shape of the guide grooves is shown, and FIG. 16 is a cross-sectional view showing a state of engagement of pins of a supporting shaft. 
     A top end portion of a supporting shaft  325  (a side of the main body  5  of the strapping machine  1  is referred to as a top end side or a front side, and the opposite side thereof, i.e., a free end side is referred to as a rear end side or a rear side) which supports a band reel  13 , is provided with a bearing  327  which is fixed to the main body of the arch type strapping machine  1 . The top end portion of the supporting shaft  325 , which extends beyond the bearing  327  into the main body  5  is fixed with a pulley  329  which is connected to an electromagnetic brake (not shown) by means of belt  331 . 
     A collar  333  is fixed to a rear side of the supporting shaft  325  with respect to the bearing  327 . The main body  337  of a reel portion  335  is connected to the collar  333 . The main body  337  comprises a side plate  339  (a front side plate) made of a thin metallic plate in which a fitting hole is formed at the center and an annular body portion  343  made of a thin metallic plate. The annular body portion  343  has, at its an end (front end), a bottom portion  341  having a fitting hole at its center, fixed to the side plate  339  and at its other side (a rear side), an opening having a smaller diameter than the fitting hole of the side plate  339 . A cylindrical portion  345  of the collar  333  is inserted into the fitting hole of the side plate  339  and the fitting hole of the bottom portion  341 . On the other hand, the side plate  339  and the bottom portion  341  are fixed to a flange portion  347  of the collar  333 . Thus, the main body  337  of the reel portion  335  is attached fixedly to the collar  333 , i.e., the supporting shaft  325 . 
     The reel portion  335  is adapted to fit a band roll  317 , in which the strapping band  11  is wound around a core member  349 , to an outer circumference of the annular body portion  343  and to attach the side plate  339  and the other side plate  351  (a rear side plate) to the supporting shaft  325  so that the strapping band  11  is held between both the side plates  339 ,  351 . The rear side plate  351  is assembled to the nob  353  (or a cap). Namely, the rear side plate  351  is attached to the supporting shaft  325  by fixing the nob  353  to the supporting shaft  325 . 
     The nob  353  comprises a cylindrical portion  355  to which a rear end portion of the supporting shaft  325  can be fitted and a handle portion  357  fixed to a rear end of the cylindrical portion  355 . The rear side plate  351  is assembled to the nob  353  by inserting the cylindrical portion  355  into a fitting hole formed at the center of the rear side plate  351 . In the cylindrical portion  355  of the nob  353 , two guide grooves  359  extending spirally from its front end portion to the rear portion at a distance of 180° wherein a recess  361  recessed in a front direction (or extending slightly in a front direction) is formed at a rear end of each of the guide grooves  359 . Two pins  363  are also formed in a rear portion of the supporting shaft  325  at a distance of 180° so as to correspond to the guide grooves  359 . The height of the pins  363  is slightly lower than the thickness of the cylindrical portion  355 . An annular groove  365  is formed in a rear side surface of the handle portion  357  of the nob  353 , and a head portion of a compression coil spring  367  having a truncated cone shape is fitted to the annular groove  365  so that the rear side plate  351  is pressed toward the band roll  317  whereby the band roll  317  is held between the both side plates  339 ,  351 . In FIG. 14, reference numeral  369  designates a C-ring which prevents the rear side plate  351  from coming off. 
     In order to attach the nob  353  to the supporting shaft  325 , each opening formed at the top end of the guide grooves  359  of the nob  353  is made coincident with each of the pins  363  of the supporting shaft  325  (FIG. 16 shows such state), and the nob  353  is pushed to the shaft. Then, the nob  353  is moved forwardly while rotating around its own axis whereby it can be fitted to the supporting shaft  325 . When the pins  363  reach the rear end portion of the guide grooves  359 , the rotation and the advance of the nob  353  are stopped. However, before the movement of the nob  353  is stopped, the band roll  317  comes to contact with the outer circumference and so on of the rear side plate  351 , and the compression coil spring  367  is compressed between the rear side plate  351  and the nob  353  at the time of the completion of pushing the nob  353 . Accordingly, when the pushing force to the nob  353  is removed, the nob  353  is moved in a direction of coming-off from the supporting shaft  325  (i.e., a rear direction) by the spring action of the compression coil spring  367  compressed between the nob  353  and the rear side plate  351 . As a result, the pins  363  are fitted to the recesses  361  so that the nob  353  is engaged with the supporting shaft  325  so as not to cause the rotation. When the nob  353  is to be removed from the supporting shaft  325 , the nob  353  should be pushed against the spring action of the compression coil spring  367  to disengage the pins  363  from the recesses  361 , and the nob  353  is pulled while rotated slightly. Thus, the nob  353  can be disengaged from the supporting shaft  325  under the rotation. 
     Thus, in the above-mentioned embodiment, the nob can be fitted to the supporting shaft by making the openings of guide groove coincident with the pins and pushing the nob, whereby the nob is advanced according to the relative movement and rotation of the pins with respect to the guide grooves. When the pins reach the rear end (i.e., inlets of recess) of the guide grooves, the movement of the nob is stopped. In this case, the nob is moved in a rear direction by weakening the pushing force to the nob since the nob is urged in a rear direction (a direction capable of coming-off from the supporting shaft) by the spring member disposed between the nob and the reel portion. As a result, the pins are fitted to the recesses whereby the nob can be fixed to the supporting shaft in a non-rotatable manner. 
     In a preferred embodiment of the present invention, the rear side plate of the reel portion is attached to the nob (in many cases, the side plate is assembled to the cylindrical portion of the nob). Then, the assembling or disassembling of the side plate can be conducted together with the removal or the attachment of the nob. 
     In order to obtain a certain fixing state of the nob to the supporting shaft, it is preferable to form two guide grooves and recesses and two pins in correspondence with the guide grooves. 
     As described above, in accordance with the arch type strapping machine having the sealing mechanism of the present invention, one continuous revolution of the shaft for sealing having a cam for driving can be performed without stopping it. Accordingly, the steps of cutting and melt-bonding of the strapping band can be conducted quickly. 
     Further, according to the arch type strapping machine having the driving mechanism for the strapping band, the band feeding step, the first and second tightening steps can be performed by only the rotation and driving of the band driving roller. Accordingly, the size of the strapping machine can be reduced. 
     Further, according to the arch type strapping machine having the band driving-out mechanism of the present invention, the remaining of the strapping band in the groove of the band guide at the time of opening the band guide can be prevented. Further, the push pin can follow the movement of the band guide even when the band guide shakes at the time of opening of the band guide. Accordingly, a smooth opening operation of the band guide can be maintained. 
     Further, according to the arch type strapping machine provided with the band reel for the strapping band of the present invention, the replacement of band rolls can quickly and simply be conducted. The entire disclosures of Japanese Patent Application No. 2001-110233 filed on Apr. 9, 2001, Japanese Patent Application No. 2001-110234 filed on Apr. 9, 2001, Japanese Patent Application No. 2001-112059 filed on Apr. 10, 2001 and Japanese Patent Application No. 2001-112060 filed on Apr. 10, 2001 including specifications, claims, drawings and summaries are incorporated herein by reference in their entireties.