Abstract:
An apparatus for tensioning a band, in particular a strapping device, includes a drive unit ( 10 ) which, in the operated state, drives a band winding unit ( 12 ) selectively in opposite directions of rotation. As a result of the band ( 18 ), which can be inserted into the apparatus, being releasably locked in predefinable positions by an operating device ( 14 ) actuated by a control device ( 16 ) of the band winding unit ( 12 ), functional positioning of the band winding unit is started to fix the band. The band can be inserted into the apparatus, in the tensioned or tautened state to then be able to insert the band tensioning apparatus for a new strapping operation after the band is severed.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an apparatus for tensioning a band, in particular a strapping device. The apparatus has a drive unit which, in the actuated state, drives a band winding unit selectively in one of opposite directions of rotation. 
   BACKGROUND OF THE INVENTION 
   Band tensioning apparatus and strapping devices are readily available on the market in a plurality of embodiments. The known solutions, however, have been found to be difficult to manage in manual use, whether due to their dimensions or due to their weight in use. The known solutions are also to some extent costly to produce and are fault-susceptible in operation due to their construction. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to develop an apparatus for tensioning a band allowing economical production, being reliable and being easily handled in use with reduced geometrical dimensions. 
   This object is basically achieved by an apparatus with an actuating device which can be triggered by the control device of the band winding unit. The band insertable into the apparatus is releasably locked in definable positions. The operating position of the band winding unit is used to fix the band which can be inserted into the device in the tensioned or tightened state. Then, the band tensioning apparatus can be used for a repeated strapping process after the band is cut. Due to this mechanical positive coupling, the winding and locking processes, in addition to loosening the band for a re-attachment process, proceed entirely automatically. This operation greatly simplifies handling in terms of actuating processes. This mechanical trigger device can also be housed in a space-saving manner within the apparatus so that the solution according to the present invention is geometrically small and need have only a small weight in use. Moreover, the apparatus with its mechanical trigger components can be economically implemented or produced. As a result of the triggering processes of diverse control parts of the apparatus which proceed largely automatically, a reliable tensioning or strapping process is ensured. 
   In one especially preferred embodiment of the apparatus according to the present invention, a rotatable cutting means for the band is integrated in the housing of the apparatus, and can be guided in a slot guide provided with at least one cutting blade in the rotary position allowing the band to be cut. In this way, within the device another function is implemented, specifically that of cutting, in addition to the functions of winding and locking of the band. Preferably, to drive the rotatable cutting means, a rod drive is used which can be actuated by parts of a lever mechanism which causes the winding processes and the attachment and release of the band inserted into the apparatus. As a result of the mechanical positive coupling by the rod drive, in this respect a reliable sequence is ensured since triggering of a function at the same time triggers the following function in a defined manner. 
   In another especially preferred embodiment, the drive unit is a pneumatic motor having two opposite directions of rotation, and interacting with the band winding unit by a worm drive. Since commercial buildings generally have pneumatic supply means, the pneumatic motor can be connected to a compressed air supply almost anywhere allowing extensive independence when using the tensioning apparatus on site. With a pneumatic motor high forces can be applied and still a limit can be defined depending on the maximum definable working pressure. Even in the case of improper operation, the drive motor cannot then damage the mechanical components of the apparatus. This pressure limitation overall also benefits the safety of the apparatus in use. Otherwise the use of pneumatic drives has little susceptibility to dirt so that the apparatus according to the present invention can also be used in challenging areas such as the food industry, the pharmaceutical industry, electronics industry, etc. Fundamentally, the use of other drive concepts is also possible. 
   The apparatus according to the present invention for tensioning of a band can be used for almost any band size and for any packaging purpose in which a band for the purpose of strapping is placed around the packaged article and then tightened, for example, to bundle several packaging units of the packaged article to one another. 
   Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure and which are schematic and not to scale: 
       FIG. 1  is a perspective view of a band tensioning apparatus with a winding and cutting means according to a first exemplary embodiment according to the present invention; 
       FIG. 2  is a side elevational view of one part of the apparatus shown in  FIG. 1 , without the cutting means; 
       FIGS. 3 to 8  are side elevational views of the tensioning apparatus of  FIG. 1  in different operating positions; 
       FIG. 9  is a perspective view of part of the tensioning apparatus of  FIG. 1 , with the housing partially cut away; 
       FIGS. 10 to 13  are side elevational views of a tensioning apparatus according to a second exemplary embodiment of the present invention; and 
       FIGS. 14 and 16  are side elevational views and  FIGS. 15 and 17  are plan views of a tensioning apparatus according to a third embodiment of the present invention, modified relative to the control device. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a perspective side view of a band tensioning apparatus used as a strapping apparatus, but without the band to be tensioned. The tensioning apparatus shown in  FIG. 1  has a drive unit  10  which in the actuated state drives a band winding unit  12  selectively and alternatively in opposite directions of rotation. By an actuating device or actuator  14  triggered by a control device or control  16  of the band winding unit  14 , which will be detailed below, a band or strapping band  18  inserted into the apparatus, not shown in  FIG. 1 , can be releasably locked in definable positions. To cut the band, a cutting means or cutter  20  ( FIG. 4 ) is used. All these components of the tensioning apparatus are integrated in a tensioning housing  22  of the apparatus. This tensioning housing  22 , as viewed in  FIG. 1  on its underside, has a plate-like support shoe  24 . The underside of support shoe  24  makes it possible to support the apparatus on a packaged article. On its opposite exposed top, a guide surface  26  guides the band to be tensioned. 
     FIG. 2  shows a face or side view of the tensioning apparatus of  FIG. 1  with the tensioning housing  22  partially cut away for better representation of the interior operation of the apparatus. In  FIG. 2 , the cutting means  20  is omitted since in the basic embodiment the illustrated apparatus can also be used as a pure band tensioning apparatus with cutting of the band taking place outside the device, for example, with a separate cutting means in the form of a knife (not shown). The band  18  is shown schematically in  FIG. 2 . The band  18  can be a steel band, a plastic band or one with steel or plastic reinforcing. In the closed state shown in  FIG. 1 , the band straps a packaged article (not shown) held in the winding loop  30 . In particular, glued bands or those woven from plastic fibers are used. 
   Since the band  18  is generally used for a standard strapping process of a defined packaged article, the length of the band is fundamentally given in defined stages of size. For each type of packaged article, a defined band length is then available. The packaged article can also have several parts so that several packaging units can be held together in a bundle and therefore in a lot size by the band  18 . The tensioned and strapped band  18  is used to stiffen the packaged article. In particular when using cardboard as the packaging jacket, the packaging is additionally secured by the band. These relationships are recognized so that they will not be detailed here. Before their processing, the bands can have an exactly defined length matched to the packaged article. With the apparatus according to the present invention, use of any band length is also possible. 
   For better understanding, the band  18  with its one free or first end  32  is looped around an eye or thimble  34  in a self-locking manner. The other free end  36  of the band is held within the band winding unit  12  after a certain number of turns or loops. Since the number of loops is limited, the length of the band should always be chosen such that not too many turns arise on the band winding unit  12  which can then no longer be handled by the device. The band length, however, should not be too short since otherwise tightening of the band  18  and its attachment on the band winding unit  12  can be at risk. In a system state shown in  FIG. 2 , the band  18  is clamped within the tensioning apparatus. By winding the band  18  on the band winding unit  12 , the eye or the thimble  34  together with the free band end  32  is tightened in the direction of the arrow X to the tensioning housing  22 . This tightening shortens the free length of the tensioning band  18  with the result that the band  18  can be placed tightly around the packaged article (not shown). 
   When this tensioning and winding process is completed, the band  18  can be severed, for example, at the cutting site  38  by a separate cutting means or blade means. The strapping process would then be completed. Instead of the band  18  being a flat body, the band could also be a wire-shaped body. A multiple superimposed arrangement of bands  18  (not shown) could be attached to a third article, such as a packaged article, strapping it. If the band  18  has been cut off at the cutting site  38 , by the self-locking of the parts of the eye or cramp for the eye  34 , the band  18  in its tensioned position is held by locking. 
   The control device or control  16  shown in  FIG. 2  has a first control part  40  with first control cams  42 . These control cams  42  extend in pairs diametrically opposite one another around the longitudinal axis  44  of the band winding unit  12 . A second control part  46  with a second control cam  48  of another type is provided. This control cam  48  is present only once, and extends with its outside diameter along a graduated circle larger in diameter than the pivoting circle of the control cams  42  in their maximum possible pivoted-out position. Both control parts  40 ,  46  can be entrained at least in one direction by the winding shaft  50  of the band winding unit  12 . The graduated circle of second control cam  48  need not necessarily be larger. The winding shaft  50  is made as a cylindrical driving pin, and in the center has a continuous longitudinal slot  52  used to entrain the end region of the other or second end  36  of the band. Instead of one longitudinal slot, several longitudinal slots can be provided. If five control cams  42  are used, a diametrically opposite arrangement is replaced by one in which the distances of the control cams  42  in the radial peripheral direction to one another are the same. In each instance, the control cams  42  are preferably located on the same graduated circle. 
   One of the two control parts, here the control part  40 , is provided with a freewheeling means, freewheel device or automatic clutch  54  such that in one of the two possible directions of rotation, as viewed in  FIG. 2 , the second control part  46  can be entrained or rotated clockwise by the winding shaft  50  without the transfer of force or retains the position it has assumed. In this respect, the control cams  42  of the control part  40  maintain their illustrated position, and together with the second control part  46  turn counterclockwise. In the other direction identified with the arrow Y in  FIG. 2  and accordingly counterclockwise, the control parts  40 ,  46  tend to move in the other direction. The second control part  46  with its control cam  48  then forms an abutment for parts of the actuating device  14 . The freewheeling means  54  shown in  FIG. 1  is implemented by individual freewheeling bodies held in the inner and outer ring parts of the tensioning housing  22  and the band winding unit  12 . These freewheeling means are within the prior art so that they will not be described in detail. 
   As follows from  FIG. 2 , the actuating device  14  comprises a multipart lever drive, including a first lever  56  made as an angle lever being triggerable by a first control part  40  with its control cam  42 . Another or second lever  58  also made in the form of an angle lever can be triggered by the second control part  46  with its control cam  48 . Both levers  56 ,  58  for their actuation on their free end have a curve roller  60  so that they can slide better on the paths formed by the control cams  42 ,  48 . The other lever  58  on its other free end is pivoted in the tension housing  42  via an axis  62  of rotation. Another or third actuating lever  64  is rigidly coupled to the lever  58 , and via another articulation  66  bears a foot-shaped locking means or lock  68  for clamping or tightening the band  18 . The underside of the locking means  68 , as shown in  FIG. 2 , is provided with fluting to increase the force of engagement with the band surface  18 . 
   In the region of the lower third of the actuating lever  64 , as viewed in  FIG. 2 , behind that lever  64 , the lever  56  is coupled by a third axis  70  of rotation. An energy storage device in the form of a tension spring  72  biases the rear angle piece of the angle lever  56  to pivot counterclockwise around the third axis of rotation  70 . Another energy storage device in the form of a compression spring  74  presses or biases the upper end of the lever  58  counterclockwise. This compression spring  74  is shown only as a functional element in  FIG. 2 , and is otherwise implemented as shown in  FIG. 9  by a leg spring  76  for practical execution. The tension and compression springs can also be replaced by compression and tension springs, respectively, which, however, attach analogously elsewhere with their required force action. The angle lever  56  on its end opposite the curve roller  50  has a contact flank  78  in contact in the operating position shown in  FIG. 2  with a catch support  80  which in the region of potential sliding off of the contact flank  78  is provided with a convex guideway  82 . This catch support  80  with the formation of an abutment for the part of the lever drive is permanently connected to the housing  22  of the tensioning apparatus and is part of it. 
   The drive unit  10  preferably has a pneumatic motor, but could also have an electric motor or the like. The pneumatic motor has a rod on its one free face side ending in a drive pinion  84 . Drive pinion  84  meshes with a continuous worm drive  86  which drives the winding shaft  50  of the band winding unit  12 , counterclockwise (arrow Y) or in the opposite direction Z (see  FIG. 7 ) depending on the direction of drive rotation of the pneumatic motor. The housing parts of the pneumatic motor are seated outside on the tensioning housing  22 . The rotatable parts of the pneumatic motor, in particular in the form of the drive pinion  84 , are guided within the housing  22 . 
   The control cams  42  (a total of six) of the first control part  40  are arranged at discrete distances from one another extending along the closed curve path extending concentrically to the winding shaft  50 . In this first embodiment, the control cams  42  are movable around a pivoting axis  88  against the action of another energy storage device in the form of compression springs  90 . A different number of control cams  42  is possible. In this respect, the pivoting control cams  42  are held in at least the direction of rotation Y of the winding shaft  50  in the trigger position for parts of the lever drive in the form of the curve roller  60  of the angle lever  56 . The second control part  46 , as already described, has a control cam  48  forming on the outer peripheral side an involute path with control flanks  92 ,  94  tapering conically to its free end. Control flank  92  forms an abutment surface for parts of the lever drive in the form of a curve roller  60  for the upper angle lever  58 . 
   The embodiment as depicted in  FIG. 2  is shown without the cutting means. The  FIG. 2  arrangement is sufficient to bring about an attachment process for a band  18 . To complement the version shown in  FIG. 2 , a complete attachment cycle for the band  18  is described below using  FIGS. 3 to 8  with inclusion of the cutting means or cutter  20 . The band is only partially shown in the figures and only with its relevant regions. 
   The cutting means shown in  FIG. 3  et seq. can be pivoted, and is made comparably to the winding shaft  50  as a hollow sleeve  96  which in the expanded inner peripheral region has a cutting blade  98  projecting in the manner of a fin. Blade  98  has a free cutting edge projecting in the direction of the continuous longitudinal slot  100 , and is connected as a pivoting cutting means  20  to a triangle lever  102  (cf.  FIG. 3 ) triggered by a rod drive  104  via the lever drive. The lever drive acts pivotally on the longitudinal rod of the rod drive  104  by a lever piece  106 . The rod drive  104 , on its opposite free end, is articulated to the end of the triangle lever  102 . 
   As  FIG. 3  et seq. show, the hollow sleeve  96  remains in its position. The cutting blade  98  is pivoted counterclockwise via the rod drive  104  and the lever drive with the lever piece  106  out of its cutting position shown in  FIG. 3  into a neutral position shown in  FIG. 5  within the hollow sleeve  96 . Blade  98  can then be rotated clockwise in turn into the cutting position shown in  FIG. 8 . 
   According to the initial or base position as shown in  FIG. 3 , the cutting blade  48  is held in the cutting position, and the locking means  68  is held in the opened position, i.e., the base plate or clamping plate is raised, as shown, toward the top over the lever drive. The drive device  10  is not actuated. The band  18  (not shown) is wrapped around the packed article or packaging article, and is inserted into the attachment clasp in the form of the eye  34  as shown in  FIG. 2 . The band  18  is placed on the guide surface  26  of the housing  22  by the band  18  being pulled through between the locking means  68  and the guide surface  26 . The upper free end of the band is not yet inserted into the tensioning apparatus. 
   As shown in  FIGS. 4 and 5 , the drive unit  10  is then turned on for producing rotation counterclockwise in direction Y. As a result of the worm drive in the form of a continuous worm, the clockwise direction of rotation results in the winding shaft  50  also being rotationally entrained counterclockwise. The control cams  42  coupled to the disk-shaped first control part  40  actuate the angle lever  56  by its projecting guide roller  60 . This angle lever  56  is then moved clockwise away from the projecting end of the engaged control cam  42  by pivoting around the pivoting axis  70  so that in this respect the other angle lever  58  is released and can turn counterclockwise around the pivoting axis  62 . This rotation takes place until the clamping plate of the locking means  68  as shown in  FIG. 5  under the spring force of the energy storage device  74  is moved downwardly and clamps the band  18  in this way. 
   Then “overcentering” would take place between the movable lever parts via the lever drive made as a toggle joint lever drive. This “overcentering” accordingly raises the clamping force for the locking means  68 . For this position, the angle lever  58 , as shown in  FIG. 5 , with its guide roller  60  is in contact with the flank  94  of the control cam  48 . Until clamping of the band  18  takes place within the locking means  68 , the triggering process is also used to guide the free end of the band through the longitudinal slot  100  within the hollow sleeve  96  and to allow the end of the band to engage the longitudinal slot  52  of the winding shaft  50  for a winding process. To enable this process, by pivoting the rod drive  104  back by the lever piece  106  coupled to the angle lever  58 , the cutting blade  98  is moved out of its cutting position, shown in  FIGS. 3 and 4 , into the upper inactive position as shown in  FIG. 5 . The sharp blade edge extends parallel to the longitudinal slot  100  of the cutting means  20 . This entrainment of the lever piece  106  counterclockwise around the pivoting axis  62  is induced by the feed motion of the lever  58  under the action of the compression spring  74 . 
   As follows from  FIGS. 3 to 5 , the contact flank  78  of the angle lever  56  is first in supportive contact with the free face side of the catch support  80 . As a result of the described lever motion, first the contact flank  78  is guided along the concave face-side path of the catch support  80  until it catches underneath. At this point, sliding along the lower convex guide path  82  of the catch support  80  is induced, a movement supported by the tension spring arrangement  72 . The tension spring  72  with its two free ends is coupled on the one hand to the actuating lever  64  and on the other hand to the angle lever  56  in the region of the acting flank  78 . As soon as the position as shown in  FIG. 5  has been assumed, the drive unit  10  is stopped. The drive unit  10  in the form of the pneumatic motor is turned on and off by actuating knobs (not shown) permitting one-hand operation for the entire tensioning apparatus. For each direction of rotation of the drive unit  10 , preferably an actuating knob indicates the direction. 
   As shown in  FIG. 6 , the drive unit  10  has again been turned on and the winding shaft  50  according to the direction of rotation Y has brought about several winding processes for the end  36  of the band. The second control part  46  with the control cam  48  is then entrained via frictional engagement until the flank  92  used as the abutment surface makes contact with the guide roller  60  of the other lever  59 , extending underneath it. At this point, the band can be further wound by actuating the winding shaft  50 , and is tensioned until a set tensioning force is reached and dictated by the pneumatic motor in terms of its possible pressure balance. Viewed in the direction of  FIG. 2 , the eye or thimble  34  is pulled in the direction of arrow X toward the tension housing  22  of the apparatus. The band then straps the packaged article positively and nonpositively. If excess winding of the band material on the winding shaft  50  were to occur unexpectedly beforehand, the drive  10  could be shut off by hand in this case. 
   In the continuation of the process as shown in  FIGS. 7 and 8 , the drive unit  10  is then turned on and there is rotation in the Z direction as shown in  FIG. 7  for the winding shaft  50 . Therefore, it turns clockwise. In the opposing motion, the tension of the band  18  at the clamping site, that is, in the region of the locking means  68 , is relieved. At the same time the control cam  48  of the second control part  46  is entrained away from the stop, clockwise Z via the freewheeling or freewheeling means  54 . After approximately ¾ of a revolution the flank  94  of the control cam  48  comes into contact with the guide roller  60  of the lever  58  and the actuating lever  58  is moved clockwise against the spring force of the energy and spring storage device in the form of the compression or leg spring  74  around the pivoting axis  62 . Due to this motion of the lever  56 , as shown in  FIG. 8 , the clamping plate of the locking means  68  is raised, and then releases the band  18 . At the uppermost curve point, the lever  58  with its contact flank  78  then passes the edge of the stationary catch support  80 , and is then turned counterclockwise around the pivoting axis  64  by spring force and is supported in turn on the free face side of the catch support  80 . Accordingly, this actuating lever  56  is fixed in this position when the clamp is opened. 
   With the opening of band clamping, by the rod drive  104  the cutting blade  98  is pivoted clockwise via the triangle lever  102  and is moved into its cutting position shown in  FIG. 8 . In this cutting position shown in  FIG. 8 , the band  18  is severed on the end side at that location. The spring-loaded control cams  42  sliding past the curve roller  60  of the angle lever  56  are folded or pivoted away against the spring force, and thus, do not hinder the release process for the band. The drive unit  10  can then be turned off. With respect to the severed band  18  with the band clamping opened, the tension apparatus can be removed. The band residue which remains on the winding shaft  50  as shown in  FIG. 8  can then be easily removed by hand. The band tensioning apparatus is then available for a repeated tensioning process according to its initial position as shown in  FIG. 3 . 
   In the second embodiment shown in  FIGS. 10 to 13 , the disk-shaped control part  40  interacting with the winding shaft  50  is equipped with stationary control cams  42   a  instead of the spring-loaded, movable control cams  42 . To achieve the same action as described above, in addition to the angle lever  56 , another angle lever  108  is provided having the same pivoting axis  70  as the lever  56 . The free end of angle lever  108  overlaps the other angle  56  in the region of the contact flank  78  on the end side with an overlap piece  110  (cf.  FIG. 12 ). In this contact position, the angle lever  108  is held via another tension spring  112 . The overlap piece  110  ensures that the angle lever  56  with its contact surface  78  can extend underneath, engaging the stationary catch support  80 , according to the foregoing description (cf.  FIG. 13 ). 
   In the third embodiment shown in  FIGS. 14 to 17 , the control disk as the first control part  40  connected securely to the latter, viewed in the direction of  FIGS. 14 and 16 , has control cams  42   b  projecting to the rear. If, as already described, the drive unit  10  is turned on, the direction of rotation Y is to result and the winding shaft  50  turns counterclockwise. The control disk is the driver disk  114  permanently connected to the winding shaft  50 . An actuating disk  116 , pivotally guided on the winding shaft by a conventional bearing site  118  provided with freewheeling, has a spring-loaded actuating pin  120 . Viewed in the direction of  FIGS. 14 and 15 , actuating pin  120  keeps a projecting actuating journal  122  in contact with the projecting, underlying stationary control cam  42   b . When the actuating disk  116  continues to be pivoted in the direction of rotation Y, the actuating pin  120  comes into contact with a control housing part  124 , and, as shown in  FIGS. 16 and 17 , is pressed to the inside against the actuating force of the spring arrangement of the actuating pin  120 . The actuating journal  122  guided to the inside disengages from the pertinent control cam  42   b . This action leads to decoupling of the control disk  114  as a control part  14 . The winding shaft  50  can then continue to turn counterclockwise Y. In the process, the control flank  92  in turn comes into contact with the lever  58 , extending underneath it. The operation description above in this respect applies to the continuing sequence of motions and also to the illustrated modified embodiment. 
   While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.