Abstract:
A band feed length adjusting device in a packing machine which can newly input, to a control section, a length obtained by manually leading out a band to adjust the feed length of the band and can subsequently feed the band having a correct length in the case in which the size of an object to be packed is changed to be larger.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a band feed length adjusting device in a packing machine, and more particularly to a band feed length adjusting device in a semi-automatic packing machine which can feed a band having a proper length at a next banding operation if a fed band is short. 
     2. Description of the Related Art 
     For example, as shown in FIG. 4, a semi-automatic banding packing machine comprises a band reel  1  provided under a packing machine body  4 . A band led from the band reel  1  is caused to pass through a suspension roller  2  and then through a roller  3  of a brake arm and is thereafter inserted in a hole  5  provided on the packing machine body  4 . In this manner, a first band insertion is carried out. 
     In such a semi-automatic machine, the packing machine body  4  includes band feeding means A having a driving roller  7  and a touch roller  9  and band returning means B having a driving roller  8  and a touch roller  10  as shown in FIG.  5 . In the semi-automatic machine comprising such a band feeding device, when one of the means is driven, the other means is stopped. Thus, the band can freely be moved between the rollers on the stop side. 
     In order to carry out banding, when a band feeding switch  14  is first turned on, the operation of the band feeding means A is started in response to an instruction signal sent from a controller so that a band having a predetermined length is pushed out toward the upper surface side of the packing machine body  4 . Then, the tip of the band thus pushed out is wound upon the periphery of an object to be packed and is inserted into the packing machine body. Consequently, the tip of the band abuts on a limit switch provided on the band feeding device in the packing machine body so that operation of the band returning means B is started and the band is then returned in a reverse direction. Thus, the band is consecutively returned and tightened. 
     In addition to such a structure that permits the band to be fed by means of two roller pairs and then returned and tightened, a band feeding device is also known in which the band is fed and returned and tightened by means of one roller pair. For example, as shown in FIG. 6, a driving roller  11  is constructed to be reciprocally rotatable and a touch roller  12  abuts the roller  11  so that the band can be selectively fed and tightened by means of a roller pair. 
     In a conventional semi-automatic banding machine, the feed length of the band by the band feeding means A is typically adjusted by controlling by means of a timer a time required for rotating the driving roller  7 . 
     However, an object to be packed has various sizes. Accordingly, if an object to be packed having a certain size is banded and a next object to be packed having a larger size is to be then banded, the band having a current feed length cannot be wound upon the larger object to be packed. In that case, conventionally, the band shortage has been adjusted by manually pulling out the tip of the band without changing the set time of the timer. 
     However, even if the length of the band is thus adjusted, a countermeasure is taken only once. Therefore, also in the case in which the banding is to be subsequently carried out, only the band having a current small length is fed. Accordingly, the length of the band is still insufficient. Therefore, the insufficient part should be led out again. 
     SUMMARY OF THE INVENTION 
     In consideration of the above-mentioned circumstances, it is an object of the present invention to provide a band feed length adjusting device in a packing machine which can newly input, to a control section, a value obtained by manually leading out a band to adjust the feed length of the band at a first work and can subsequently feed the band having a correct length in the case in which the size of an object to be packed is changed to be larger. 
     In order to achieve the above-mentioned object, the present invention provides a band feed length adjusting device in a packing machine in which 
     a plurality of detecting portions are provided at regular intervals on a side surface of a touch roller which is opposed to a normal rotating roller or a reverse rotating roller and serves to selectively abut on one of the two rollers, thereby constituting band feeding means or band reverse rotating means, and furthermore, 
     a sensor for detecting the detecting portions is provided to face an outer periphery of the touch roller, 
     wherein when an amount of the band led from a band reel through a driving operation of the band feeding means for winding onto an object to be packed is insufficient, the band having a length corresponding to the shortage is led from the band reel through a manual operation and 
     the detecting portions of the touch roller thus moved are detected by the sensor and a result of the detection is supplied to a control section, thereby automatically adjusting a band length required for subsequent band feeding. 
     According to the present invention having the above-mentioned structure, it is possible to measure the shortage of the length of the band led out by means of the sensor. Consequently, if the shortage of the length of the band is newly input to the control section, the band having a length correctly set can be subsequently fed. 
     As described above, in the band feed length adjusting device in the packing machine according to the present invention, the amount of the band to be led out is automatically calculated through the rotation of the touch roller and is added to the feed amount for the subsequent banding. Therefore, in the case in which the size of the object to be packed is changed to be larger, the band feed length can be adjusted automatically. 
     These objects as well as other objects, features and advantages of the present invention will become more apparent to those skilled in the art from the following description with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view showing a packing machine comprising a band feed length adjusting device according to an embodiment of the present invention, 
     FIG. 2 is a sectional view showing a band feeding device provided in the packing machine, 
     FIG. 3 is a schematic view showing a rotation detecting section provided in a touch roller of the band feeding device, 
     FIG. 4 is a schematic view showing a conventional packing machine, 
     FIG. 5 is a front view showing a band feeding device provided in the conventional packing machine, and 
     FIG. 6 is a front view showing another conventional band feeding device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will be described below with reference to the drawings. 
     FIG. 1 shows a semi-automatic packing machine  33  according to the embodiment of the present invention. 
     In the packing machine  33 , a band reel  28  having a long band D wounded thereupon is accommodated in the lower space of a packing machine body  30 . 
     A band feeding device  32  for feeding and returning a band is positioned on a lower surface of an upper surface table  31  on which a small object w to be packed, a large object W to be packed or the like is to be placed. 
     The band feeding device  32  has a structure that includes a normal rotating roller  20  for feeding the band D to the side of the object to be packed and a reverse rotating roller  21  for returning the band D toward the guide roller  40  side at a predetermined interval. A touch roller  22  is opposed to the two rollers  20  and  21  as shown in FIG.  2 . The touch roller  22  is movably provided to selectively abut on the peripheral surface of the normal rotating roller  20  or the reverse rotating roller  21  through position changing means which is not shown. Moreover, a clearance to permit free insertion of the band D therethrough is maintained between the roller  21  and the roller  22  or between the roller  22  and the roller  20 . In addition, since the reverse rotating roller  21  is formed of metal, the band D is not wound upon the roller  21  to create a resistance even if it is pulled in a direction of an arrow C. 
     In the band feeding device  32  having such a structure, a band path is maintained between the rollers. Therefore, a low resistance is generated when the band D is to be pulled out in the direction of the arrow C. Moreover, the band D is wound upon the touch roller  22 . Therefore, even if the band D is pulled in any direction, the touch roller  22  can be rotated. 
     On the other hand, a plurality of holes  24  is formed on the side surface of the touch roller  22  at regular intervals along an outer peripheral side surface as shown in FIG.  2 . Furthermore, a sensor  25  for detecting the holes  24  is fixed to face the side surface of the touch roller  22 . 
     As shown in FIG. 3, the sensor  25  comprises an optical sensor, a magnetic sensor or the like. A movement distance coincident with the rotation of the touch roller  22  is detected by the sensor  25 . More specifically, the holes  24  pass through the optical beam of sensor  25  so that the travel distance of the outer peripheral surface of the touch roller  22  is detected. The movement distance is equivalent to the amount of band feed. A detection signal is counted through a counter  26 , and is stored in storage means  27  and is output to a control section  29 . 
     In the semi-automatic packing machine  33  comprising the band feeding device  32  described above, for example, in the case in which the small object w to be packed is banded and the large object W to be packed is then banded, the feed amount of the band is set in the control section  29  such that the band having a small length is still fed. 
     As shown in a dotted chain line of FIG. 1, the object w to be packed which has a small size is provided on the upper surface table  31 . 
     For the band feeding operation in this state, the touch roller  22  abuts on the peripheral surface of the normal rotating roller  20  in response to a signal sent from the control section  29  and thus constitutes band feeding means A together with the normal rotating roller  20 . In other words, the touch roller  22  separates from the reverse rotating roller  21  and the band D can freely reciprocate therebetween. 
     The band feeding means A is driven by a pulse set number provided in the control section  29  and the band having a predetermined length is fed toward the object w to be packed. However, the band thus fed has such a length as to be simply wound upon the small object w to be packed. In order to correctly carry out the banding over the object W to be packed (shown in a solid line) having a greater width and height than smaller object w, it is preferable that the following operation should be performed. 
     First of all, a worker grips the tip of the band extended up to the middle by hand to lead out the band having such a length as to correspond to a shortage from the band reel  28 . Consequently, the touch roller  22  is rotated in a direction of an arrow E in FIG. 2 corresponding to the length of the band D pulled in the direction of the arrow C. The amount of the rotation of the touch roller  22  in the direction of the arrow C is detected through the detection of the movement of the holes  24  by means of the sensor  25 . A detection signal is counted by the counter  26 , and is then stored in the storage means  27  and is sent to the control section  29 . Thus, a new band feed length is set. 
     On the other hand, when the worker grips the tip of the band pulled out sufficiently by hand and inserts the tip of the band into the packing machine body  30 , the tip of the band abuts on a limit switch so that the band is returned and tightened in response to the signal. Subsequently, the band having an automatically adjusted length is fed in the following manner. 
     More specifically, the band is fed through the driving operation of the normal rotating roller  20  of the band feeding means A and the touch roller  22  is rotated. At the same time, the rotation of the holes  24  is detected by the sensor  25  and a result of the detection is output to the counter  26 . A number counted by the counter  26  is compared with a number stored in the storage means  27  through comparing means. When the numbers are equal to each other, the rotation of the normal rotating roller  20  is stopped in response to an instruction signal output from the control section  29 . Thus, it is possible to feed the band having a desirable length to the side of the object W to be packed. Accordingly, it is not necessary for the worker to lead out the band by hand again. Thus, the large object W to be packed can be banded exactly. 
     While the embodiment of the present invention has been described above, the present invention is not restricted to the embodiment. In the embodiment, for example, the signal detected by the sensor  25  is input to the counter  26 , and furthermore, is supplied to the storage means  27  and is compared through the comparing means, thereby controlling the driving operation of the normal rotating roller  20 . The control can be carried out by another means and is not restricted to the embodiment. 
     Numerous modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and/or function may be varied substantially without departing from the spirit of the invention and all modifications which come within the scope of the appended claims are reserved.