Abstract:
In the strapping machine according to the invention, in which a strap guiding lance is inserted under the packaged goods through a penetrating opening provided in a pallet in order to create a circumferential strap channel into which a strap can be shot to produce a strapping, a particularly strong, but also lightweight design of the strap guiding lance is proposed, allowing rapid and precise insertion of the lance.

Description:
[0001]    The present invention claims priority on PCT Application Serial No. PCT/EP2008/002879 filed Apr. 11, 2008, which in turn claims priority on German Patent Application Serial No. 10 2007 019 605.0 filed Apr. 24, 2007. 
     
    
       [0002]    The invention relates to a strapping machine for strapping articles with a strapping band, which strapping machine includes a band guiding hoop surrounding an article to be strapped in an approximately portal-like manner at two upright sides and an upper side, and which strapping machine also includes a band guiding lance which can be displaced under a bottom side of the article, wherein the band guiding hoop and the band guiding lance in its displaced position under the article form a band guiding channel for the strapping band surrounding the article, which channel is covered by a cover at its inner sides facing the article allowing an exit of the strapping band from the band guiding channel in the direction toward the article. 
       BACKGROUND OF THE INVENTION 
       [0003]    Different techniques and equipments are known for strapping articles with strapping bands. One of the simplest methods consists in laying the strapping band—nowadays generally a plastic band of polypropylene—by hand around the article and to thread the two band ends into an apparatus operated by hand, with which they are tensioned against one another and subsequently connected rigidly with the help of a friction welding device. Especially when a larger number of articles are to be strapped, which are transported successively by means of for example a roll conveyor, strapping machines are used, where the band does not need to be laid around the article by hand, but is injected into a band channel surrounding the article to be packaged, from which it is then withdrawn in the direction toward the article while opening the closing flaps or the like covering the band channel initially temporarily, when the band ends are tensioned against each other. 
         [0004]    Particularly large articles, which can for example are machine parts, fabric bales or the like, are often fed to the strapping machine on transport pallets, wherein the strapping bands shall connect the article to be packaged rigidly with the pallet, but without drawing the strapping band around the bottom surface or base of the pallet. It is in fact desired that the strapping band is threaded through a gap between the upper side of the pallet and the lower runners of the pallet, which makes it necessary to open the band channel before arranging the article, which is present on the pallet in the strapping machine at the height of the pallet, and to close again afterwards when the desired position of the article in the machine is reached, so that the band can then be injected around the whole article into the band channel and then tensioned and closed, by which the article is rigidly connected to the pallet. So as to be able to produce such a strapping in a strapping machine, it is provided with a band guiding lance which can be moved transversely to the article below it, which, after the correct placement of the pallet carrying the article, enters between its lower runners and the upper support side and forms the band guiding channel together with the band guiding hoop overlapping the article in a portal-like manner in this entered state. After the completion of the strapping, the band guiding hoop is again withdrawn laterally from the pallet, and the article which is then connected rigidly to the pallet with the strapping band can be removed from the strapping machine. 
         [0005]    As the band guiding lance has to be fed in a cantilevered manner under the article in the comparatively small gap between the upper side of the pallet and the pallet runners, it is necessary to give it a high stiffness, so as to prevent hanging through or swinging during its movement. For this reason, the band guiding lances comprising the necessary stiffness were always very heavy components, which did not permit a high traversing speed and in particular high accelerations, so that comparatively a lot of time lapsed during the feeding and the withdrawal of the band guiding lance, during which the article had to remain motionless in its place in the strapping machine. Even though the actual strapping process, that is, the injection of the band into the band guiding channel, the tensioning of the band around the article and the welding, took place in a very short time, the number of cycles which could be achieved, that is, the number of the strappings per unit of time to be carried out at different articles, was comparatively low with such a machine. With the known band guiding lance, it was particularly problematic that the necessary stiffness could only be achieved with a comparatively large height of the lance, with which an even larger minimum height of the gap between the upper side of the pallet and the pallet runners had to be required, through which the band guiding lance had to be moved. 
       SUMMARY OF THE INVENTION 
       [0006]    It is the object of the invention to improve a strapping machine of the above-mentioned type to that effect that the band guiding lance can be injected under an article with high speed, in particular in a pallet, and can again be withdrawn from this position, without the danger of the lance hanging through or swinging, in which the height of the band guiding lance will preferably be comparably small. 
         [0007]    This object is solved by the invention in that the band guiding lance consists of a carrier profile approximately U-shaped in its cross section, which is open toward the article, which is provided with a stiffening angle extending over the length of the band channel section at the band guiding lance, preferably even over the entire length of the band guiding lance, which angle is arranged over a partial width of the carrier profile between a first side leg and the lower connection web of the carrier profile, wherein the cover for the band channel section of the band guiding lance is arranged at the upright side wall of the stiffening angle, and covers the upper side of the stiffening angle running parallel to the connection web for forming the band channel section with a distance. 
         [0008]    This particular constructive embodiment of the band guiding lance permits a particularly light, at the same time very stiff construction of thin-walled profiles or sheets which considerably reduces the mass of the band guiding channel to be moved with a comparable, if not better, stability than the known constructions, thereby permitting higher speeds than with the machines known up to now during the feeding and withdrawal of the lance. This high stiffness with a simultaneously low weight is furthermore achieved with a very uncomplicated construction, which can be produced easily, in which the carrier profile in its interior which is open towards the top is provided with the asymmetrically arranged stiffening angle at its one side leg and its lower connection web. Connection between the carrier profile and the stiffening angle can for example be made by the use of laser welding methods with maximum accuracy. Apart from the cover for the band channel and the elements serving for its securing, the band guiding lance therefore essentially consists of only two connected components, which are connected in a particularly advantageous arrangement, namely the U-shaped carrier profile and the asymmetrically arranged stiffening angle, that is, offset to one side. 
         [0009]    It has been shown to be particularly advantageous if the lower connection web of the carrier profile is provided with apertures in its partial region lying laterally adjacent to the stiffening angle, which apertures have the effect to further reduce the total weight of the lance on the one hand, but which furthermore also ensure a problem-free removal of plastic parts occurring as abrasion from the strapping band or other contaminations, which can fall into the U-shaped carrier profile from above. These contaminations can also be abrasions from the articles to be strapped, for example stone, clay or concrete particles when stones or roof tiles are strapped. As these contaminations immediately exit the carrier profile again through the apertures, it is ensured that they do not collect in the profile and can possibly impede the orderly function of the cover opening during the tensioning of the strapping band. 
         [0010]    The cover of the band channel section of the band guiding lance can in an advantageous further development of the invention be formed by flap elements, which are arranged in a flexible manner at the carrier profile and/or at the stiffening angle. An embodiment which can be mounted particularly easily and which is also very reliable results when the flap elements abut the upright side wall of the stiffening angle with a first leg in their closed position, and cover the upper side of the stiffening angle while forming the space forming the band channel with a second leg extending at a right angle from the first leg. The flap elements can for example are held in their closed position by means of spring elements, where they open during the tensioning of the strapping band and the exiting of the band from the band channel transversely to the longitudinal direction of the band against the action of the springs and immediately close again after the exit of the band. The spring elements can thereby consist of compression springs arranged between the flap elements and the second side leg of the carrier profile, which springs keep the first leg of the flap elements pressed against the upright side wall of the stiffening angle as long as the band does not press from below against the second leg of the flap element due to the tensioning process and opens this hereby. So as to keep the springs reliably in their location and to give them a guide preventing a bending of the springs, guide pins can be provided for the compression springs arranged transversely to the side wall penetrating the flap element with a tolerance. 
         [0011]    The band guiding lance is preferably provided with band deflection elements at the end regions of the band channel section formed thereby, which reliably deflect the strapping band injected into the band channel in the lower edge regions of the band channel. It is particularly advantageous if the band deflection elements are exchangeable, because they can then not only be adapted optimally for different band widths, but it is also possible in a simple manner to change the band surrounding or injection direction by exchange of the band deflection elements which are conveniently screwed to the lance for running in or out. 
         [0012]    Further characteristics and advantages of the invention result from the following description and the drawing, where a preferred embodiment of the invention is explained in more detail with an example. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  illustrates an article in perspective view strapped with two strapping bands with a strapping machine according to the invention; 
           [0014]      FIG. 2  illustrates a strapping machine according to the invention in a front view; 
           [0015]      FIG. 3  illustrates a section of a band guiding lance for the strapping machine according to  FIG. 2  in a connection region to the band guiding hoop in a side view; and, 
           [0016]      FIG. 4  illustrates the band guiding lance according to  FIG. 3  in cross section along line IV-IV in an enlarged depiction. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1  shows an article  10  which is arranged on a pallet  11  and which is secured thereto with two strapping bands  12 . The strapping bands run in a direction Q transversely to the longitudinal direction L of the article. They run along the upper side  13  and the two upright side surfaces  14 ,  15  of the article and are guided at their bottom side through apertures  16  present in the pallet  11 , so that they hold the article together with the pallet in a rigid manner. The apertures generally have a height with such dimensions that the fork of a forklift truck can be introduced into them, so as to transport the pallet with the article arranged thereon and secured by means of the strapping bands. 
         [0018]    The strapping machine serves for producing the strappings  12  at the article shown in  FIG. 1 , which is shown somewhat simplified in  FIG. 2 . The strapping machine  17  comprises a rectangular machine frame  18 , whose upright posts  19  are connected to the machine base bar  20  with a distance from one another. A roller conveyor  21  is provided between the two base bars, on which conveyor the article  10  is transported into the strapping machine in the longitudinal direction, and is transported out again after completion of the strapping. 
         [0019]    For producing the strappings, the strapping machine is provided with a band guiding hoop  22  arranged in the machine frame in a known manner, which surrounds the article  10  in a portal-like manner at the two upright side surfaces  14 ,  15  and the upper side  13 , and which forms three sides of a surrounding band channel, into which the strapping band can be injected in a manner not shown in detail and thus laid around the article. For the completion of the band channel at the bottom side of the article, the machine comprises a band guiding lance  23 , which is arranged transversely to the longitudinal direction in a displaceable manner, which forms the band channel section running below the bottom side of the article, which section completes the band guiding hoop to the surrounding band channel in the position of the band guiding lance being pushed through below the article through the aperture  16  in the pallet. The band guiding lance  23  is in a resting position laterally next to the machine, so that it does not hinder the unimpeded transport of the pallet with the article arranged thereon. When the article has reached the desired position in the machine, in which it is to be strapped, the band guiding lance  23  is moved from the side through the corresponding aperture  16  in the pallet beneath the article until it reaches its end position, in which the band guiding channel is completely closed around the article, and the band can then be injected into this in the known manner. 
         [0020]    The special embodiment of the band guiding lance  23  which is to be fed below the article through the aperture into the pallet and withdrawn therefrom with a speed as fast as possible and which has to be particularly stiff due to the cantilevered arrangement, so as not to hang through during its feeding and withdrawal, is the object of the present invention. It is shown in more detail in  FIGS. 3 and 4 . 
         [0021]    It can be seen that the band guiding lance  23  consists of a carrier profile  24 , which is approximately U-shaped in its cross section, which is open upwardly, that is, toward the article  10 , which profile is provided with a stiffening angle  26  extending over the length of the band channel section  25  at the band guiding lance, which angle is arranged over a partial width of the carrier profile  24  in its inside between a first side leg  27  and the lower connection web  28  of the carrier profile  24 . For forming the band channel section  25  in the band guiding lance, the upper side  29  of the stiffening angle  26  is provided with a cover  30 , which consists of several flap elements  31  arranged successively over the length of the band channel section, which flap elements are essentially formed by angle sheets, which are mounted at the stiffening angle  26  in a flexible manner. The arrangement is made in such a manner that the flap elements abut the upright side wall  33  of the stiffening angle  26  with a first leg in their closed position, and cover the upper side  29  of the stiffening angle while forming the space  25  forming the band channel with a second horizontal leg extending at a right angle from the first leg  32 . 
         [0022]    So as to hold the flap elements  31  in their closed position, compression springs  36  are arranged between their first legs  32  and the second side leg  35  of the carrier profile, which springs press the flap elements against the stiffening angle with a small pretension. The compression springs are guided around guiding pins  37 , which are arranged transversely to the side legs  27 ,  35  of the carrier profile and which traverse the flap elements in associated bores  38  with tolerance. 
         [0023]    It can further be seen well from  FIGS. 3 and 4  that the lower connection web  28  of the carrier profile  24  is provided with apertures  40 , which are distributed over its length in its partial region  39  lying laterally adjacent to the stiffening angle, which are respectively only interrupted by comparatively small webs  41 . At one end region of the band channel section  25  (the left end region shown in the drawing ( FIG. 3 ) formed by the band guiding lance  23 , the lance is provided with a band deflection element  42  which ensures that the strapping band  12  injected into the band channel is deflected from the band channel section in the band guiding lance into the band guiding hoop  22  or from this into the band guiding lance. The band deflection element can be designed differently for the run-in or run-out into and from the band guiding lance. It is simply clamped between the two side legs  27 ,  35  of the carrier profile by means of clamping screws, and can be removed and exchanged through this with little effort. 
         [0024]    The embodiment of the band guiding lance according to the invention, which essentially consists of simple thin-walled sheet profile elements, which are connected to one another by laser welding methods and which are processed by laser cutting methods, creates a particularly light, at the same time a very stable, stiff construction, which permits to move the band guiding lance with high acceleration values and to feed it fast under the article through the pallet for closing the band guiding hoop and to withdraw it again from the transport path after the completion of the strapping. The apertures  40  enhance reliably during the operation by allowing dirt particles as, e.g., plastic residues or abrasion from the strapped wares that enter the carrier profile  24  from clogging the free space forming laterally next to the flap elements. Plastic particles can for example develop by abrasion of the strapping band  12  used, which is drawn inwardly (arrow  43  in  FIG. 4 ) from the band channel for the generation of the strapping around the article, whereupon the flap elements open due to the tensile force acting on the strapping band—as shown in a dashed manner-, so as to close again under the action of the compression spring after the passage of the band through the band channel which is then open. 
         [0025]    The invention is not limited to the embodiment shown and described, but various changes and additions are feasible without leaving the scope of the invention. Thus, the cover of the band channel does not have to take place by essentially rigid flap elements, mounted in a flexible manner with regard to the stiffening angle, but it is feasible to provide a flexible profile strip of a rubber-like material, of plastics or the like, which then does not have to be divided over the length of the band channel section. It is also feasible without difficulty to provide the strapping machine with several strapping stations of the described type, if it is for example desired to produce two strappings at the article at the same time as shown in  FIG. 1 . The machine can also permit a rotation of the article on the pallet in the region of the strapping station in a known manner, so as to be able to thereby lay a further strapping over the faces of the article.