Patent Publication Number: US-6708605-B2

Title: Strap reserving control device for a strapping machine

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a strap reserving control device for a strapping machine, particular to one able to quickly adjust and stably control the length or amount of the packaging strap stored in a strap reserving room 
     A conventional strapping machine has a strap reserving control device for controlling a preset length of a packaging strap stored in a strap reserving room to let the packaging strap guided out for strapping an object such as a carton. 
     The conventional strap reserving control device  10 , as shown in FIGS. 1 and 2, has a balancing rod  11  and a press rod  12  respectively secured at the opposite ends of a rotating shaft  13 . The rotating shaft  13  is pivotally inserted in a shaft sleeve  14  at the outer side of a separating plate  21  of a strap reserving room  20 , letting the balancing rod  11  and the press rod  12  respectively positioned at the inner side and the outer side of the separating plate  21 . Then, the shaft sleeve  14  is secured around with a fixed base  15  having one side extending outward and making up a support frame  151 , which is provided with a micro-switch  16  on one side, and a twisting spring  17  and a stop rod  18  on the front side  152 . The twisting spring  17  has its lower end extending downward and forming a hook  171  for holding the bottom edge of the support frame  151 , and its upper end provided with a press-stopping member  172  extending horizontally above the stop rod  18 , with the bottom edge of the and of the press rod  12  pressing on the press-stopping member  172  to avoid the press rod  12  pressing directly on the press button  161  of the micro-switch  16 . 
     In operating, as shown in FIGS. 3,  4  and  5 , firstly, start a strap feed device  40  to guide the packaging strap  30  to move into the strap reserving room  20  along the top edges of the balanced rods  11 , with the packaging strap arranged to overlie on the left side and the right side on the balancing rods  11 . At this time, in case the total weight of the packaging strap  30  in the strap reserving room  20  and the overlying tension therebetween is larger than the resilience of the press-stopping member  171 , the balancing rods  11  will be pressed downward and the rotating shaft  13 , by interaction, will synchronously actuate the press rod  12  to incline downward. Simultaneously, the bottom edge of the end of the press rod  12  will press on the press-stopping member  172  as well as on the press button  161  of the micro-switch  16 , which immediately sends out a signal to turn off the power of the strap feed device  40  to stop guiding the packaging strap into the strap reserving room  20 , thus finishing one round of strap reserving. 
     On the contrary, when the packaging strap  30  in the strap reserving room  20  is guided out for strapping an article to be strapped, the force on the balancing rods  11  vanishes, and the press-stopping member  172  recovers its resilience, pushing the press rod  12  to incline upward to separate from the press button  161  of the micro-switch  16 , which in the mean time sends out a signal to turn on the power of the strap feed device  40 , which is then started to guide the packaging strap  30  again into the strap reserving room  20  for strapping in a next round. 
     However, in a conventional strap reserving control device  10 , the twisting spring  17  controls the strap-reserving amount in the strap reserving room  20  by its resilience. Under this condition, if a strapping machine is in use, the press-stopping member  172  of the twisting spring  17  will be pressed repeatedly by the press rod  12 , and hence the twisting spring  17  is liable to become tired in its elasticity and loose, weakened and even damaged, not only shortening the service life of the machine, but also failing to stably control the length or amount of the packaging strap guided in the strap reserving room  20 , and even resulting in insufficient supply of a packaging strap in the strap reserving room  20 . Besides, the resilience of the twisting spring  17  is constant and impossible to be adjusted so the strap reserving amount set in the strap reserving room  20 , which is controlled by the twisting spring  17 , can not be adjusted by the strap reserving control device  10 . 
     SUMMARY OF THE INVENTION 
     The objective of the invention is to offer a strap reserving control device for a strapping machine, applying a lever structure formed between a balancing weight device and a balancing rod to stably control the length or amount of the packaging strap stored in a strap reserving room, able to prolong the service life of the machine and lower cost for maintenance and repair. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     This invention will be better understood by referring to the accompanying drawings, wherein: 
     FIG. 1 is an exploded perspective view of a conventional strap reserving control device: 
     FIG. 2 is a perspective view of the conventional strap reserving control device: 
     FIG. 3 is a side view of the conventional strap reserving control device, illustrating a balanced rod pressed downward by the packaging strap stored in a strap reserving room: 
     FIG. 4 is a side view of the conventional strap reserving control device, illustrating the balanced rod actuating a press rod to operate: 
     FIG. 5 is a rear view of the conventional strap reserving control device, illustrating the press rod pressing on the press button of a micro-switch: 
     FIG. 6 is an exploded perspective view of a preferred embodiment of a strap reserving control device in the present invention: 
     FIG. 7 is an upper view of the preferred embodiment of the strap reserving control device in the present invention: 
     FIG. 8 is a front view of the preferred embodiment of the strap reserving control device, illustrating the locations of a balanced rod, a sensing rod and a balancing weight rod before storing a packaging strap in a strap reserving room in the present invention: 
     FIG. 9 is a cross-sectional view of the preferred embodiment of the balancing rod, the sensing rod and the weight rod in an operating condition in the present invention: 
     FIG. 10 is cross-sectional view of the preferred embodiment of a sensing switch sensing the action of the sensing rod in the present invention: and 
     FIG. 11 is cross-sectional view of the preferred embodiment of a weight member adjusted in its position on the weight-distributing rod in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of a strap reserving control device for a strapping machine in the present invention, as shown in FIGS. 6,  7  and  8 , includes a strap reserving room  50  and a strap reserving control device  60 . The strap reserving room  50  is formed by oppositely combining a separating plate  51  with a cover plate  52  with a preset interval. The separating plate  51  is bored with a through hole  511  at a lower right side and a plurality of small holes  512  around the through hole  511 . The strap preserving control device  60  consists of a balancing rod  61 , a rotating shaft  62 , a shaft sleeve  63 , a sensing rod  64 , a balancing weight unit  65  and a sensing switch  66 . 
     The balancing rod  61  has a proper length, horizontally positioned side wise to the strap reserving room  50 . 
     The rotating shaft  62  has its front end perpendicularly secured at one end of the balance rod  61  and its rear end formed with an engage portion  621 . The rotating shaft  62  is inserted through the through hole  511  of the separating plate  51  to extend outward. 
     The shaft sleeve  63  is shaped cylindrical, threadably fixed on the outer side of the separating plate  51  by means of four combining members  67  screwing through the four small holes  512  of the separating plate  51 , and provided axially with a central shaft hole  631  aligned to the through hole  511  for the rotating shaft  62  to be inserted therethrough, with the engage portion  621  of the rotating shaft  62  extending out of the shaft hole  631 . 
     The sensing rod  64  has an axial combining hole  641  in one end for the engage portion  621  of the rotating shaft  62  to be secured therein by two combing members  67 , having a predetermined length and located in the same direction of the balancing rod  61 . 
     The balancing weight unit  65  consists of a weight rod  651  and a weight member  652 . The weight rod  651  has a lateral fit hole  653  at one end for fixedly receiving the engage portion  621  of the rotating shaft  62  with a combining member  67 . Further, the respective arm of force of the weight rod  651  and the balancing rod  62  are positioned in opposite directions, with the rotating shaft  62  acting as a central fulcrum between them. The weight member  652  has a lengthwise fit hole  654  for the weight rod  651  to be inserted therethrough and a diametrical threaded hole  655  communicating with the fit hole  654 , having a bolt  656  engaging the threaded hole  655  for fixing the weight member  652  on the weight rod  651  at one of many locations. 
     The sensing switch  66  being a proximity sensor in this preferred embodiment is positioned adjacent to the sensing rod  64 , having a sensing portion  601  at one side facing the sensing rod  64  for sensing and the movement of the sensing rod  64 . 
     In operating, as shown in FIGS. 7,  9  and  10 , firstly, the strap feed device  70  is started to guide a packaging strap  80  to move orderly into the strap reserving room  50 . When the total weight of the packaging strap  80  in the strap reserving room  50  becomes larger than the preset resisting force of the weight member  652  of the balancing weight unit  65 , the weight of the packaging strap  80  will make the balancing rod  61  incline downward, and synchronously the balancing rod  61  will actuate the rotating shaft  62  to move the sensing rod  64  incline downward and force the weight rod  651  incline upward. When the sensing rod  64  shifts to a position nearer to the sensing portion  661 , the sensing portion  661  will sense and send out a signal immediately to turn off the power of the strap feed device  70  to stop guiding the packaging strap  80  into the strap reserving room  50  to finish a round of strap preserving. 
     On the contrary, as shown in FIGS. 8 and 9, when the packaging strap  80  in the strap reserving room  50  is guided out for strapping an article, the weight of the packaging strap  80  pressing on the balanced rod  61  will vanish, and the weight rod  651  will automatically move downward to its original position and the balancing rod  61  as well as the sensing rod  64  will be actuated by the rotating shaft  62  to incline upward to their original locations. Simultaneously, the sensing rod  64  separates from the sensing portion  661  of the sensing switch  66  to interrupt the signal sensed by the sensing portion  661 , and the sensing switch  66 , with the signal interrupted, turns on the power of the strap feed device  70  to let it guide the packaging strap  80  again into the strap preserving room  50  for strapping for a next round. 
     In addition, as shown in FIG. 11, the weight member  652  is adjustable in its location on the weight rod  651 . If the weight member  652  is positioned closer to the rotating shaft  62 , the distance of its arm of force to the central fulcrum becomes shorter and its relative resisting force against the balancing rod  61  becomes small, and in consequence the length or amount of the packaging strap  80  stored in the strap-preserving groove  50  become comparatively short or small. 
     Contrarily, in case the weight member  652  is moved to a position comparatively far from the rotating shaft  62 , the distance of its arm of force to the central fulcrum becomes long and its resisting force against the balancing rod  61  becomes large and hence the length or amount of the packaging strap  80  stored in the strap preserving room  50  become relatively long and large. Thus, the weight member  652  can be adjusted in its position to match with different sizes of articles to be strapped to let the amount of the packaging strap  80  stored in the strap reserving room  50  meets practical needs in strapping. 
     As can be noted from the above description, this invention has the following advantages. 
     1. The application of the relative action between the balance weight unit and the balancing rod, and the functions of sensing and detecting of the sensing rod and the sensing switch can effectively control the length or amount of the packaging strap stored in the strap reserving room. 
     2. The balancing weight unit and the balancing rod are connected on the principle of a lever structure so no tiredness of elasticity or damage may happen to them, not only economizing time and cost in maintenance and repair, but also prolonging the service life of the machine and stably and precisely controlling the length or amount of the packaging strap stored in the strap reserving room. 
     While the preferred embodiment of the invention has been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications that may fall within the spirit and scope of the invention.