Abstract:
A system for feeding articles into a processing machine via a feeding railway, the system further comprising: a supply railway intersecting the feeding railway at a crossroads; a supply stand at the end of the supply railway and a crossroads stand at the crossroads, the stands being adapted to receive a pallet with an article in a position bridging the railways; a supply carriage adapted to pass freely under a pallet received in any of the stands, to take it from the stand and to move it to another stand; and a feeding carriage adapted to pass freely under a pallet received in the crossroads stand, to take it from the stand and feed it into the processing machine.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to means for strapping articles, in particular to automated transport systems for feeding articles into a strapping machine.  
       BACKGROUND OF THE INVENTION  
       [0002]     Packaging of glass sheets is a labor-consuming job. Typically, stacks of glass sheets are transported by forklift trucks from the production line to a packaging area where they are manually encased in wooden cases or frames. The cases are then manually strapped in tensioned strap loops by means of hand-held devices providing controlled tension and bonding of the straps. The process is time-consuming, the positioning and the tensioning of the straps are not always accurate and uniform.  
         [0003]     Automated strapping machines are used in other areas of mass-production such as building blocks, bricks, slabs or tiles. Such machines, for example SIGNODE® vertical or horizontal strapping machines, automatically feed the strap from a wheel along a closed frame to form a loop, then position a stack of blocks in the frame, tension the strap loop about the stack, bond the ends of the loop and cut the bonded loop off the wheel. Strapping of the above products does not require particular accuracy of strap positioning or tensioning.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with one aspect of the present invention, there is provided a system for feeding articles into a processing machine, such as stacks of glass sheets, into a strapping machine. The articles have length, width and height, and each article is supported on a pallet along the length. The processing machine is adapted to receive the articles moving along a first axis in an orientation where the length is parallel to the first axis. The system comprises:  
         [0005]     a) a supply railway transverse to the first axis;  
         [0006]     b) a feeding railway along the first axis;  
         [0007]     c) a crossroads at the intersection of the supply and the feeding railways allowing through passage along both railways;  
         [0008]     d) a first supply stand built at a first end of the supply railway and adapted to receive the pallet in a position bridging the supply railway, with the article in said orientation;  
         [0009]     e) a crossroads stand built at the crossroads and adapted to receive the pallet in a position bridging both the supply railway and the feeding railway, with the article in said orientation;  
         [0010]     f) a supply carriage adapted to run along the supply railway, to pass freely under the pallet received in the supply stand or in the crossroads stand, to take the pallet from the supply stand, to carry it and to leave it on the crossroads stand;  
         [0011]     g) a feeding carriage adapted to run along the feeding railway, to pass freely under the pallet received in the crossroads stand, to take the pallet from said crossroads stand and to feed it into the processing machine for processing the article supported on the pallet;  
         [0012]     The system includes an automated control system to control movements of the carriages.  
         [0013]     Each of the carriages has a moveable platform which, in lowered position, allows the carriage to pass under the pallet received in any of the stands. By moving to a raised position, the platform allows lifting the pallet from any of the stands and carrying it past any of the stands. By moving to the lowered position, the platform can leave the pallet on any of the stands.  
         [0014]     The supply railway may be extended beyond the crossroads and a second supply stand may be built at the second end of the supply railway. At least one additional supply stand may be built between the crossroads and either or both the first and the second supply stands, such that additional pallets may be simultaneously positioned on these additional supply stands by means of the supply carriage.  
         [0015]     The feeding railway may be extended to an operative area of the processing machine and preferably to an unloading area beyond the processing machine. The feeding carriage may be adapted to carry the pallet with the article thereon to the operative area and to preferably to the unloading area.  
         [0016]     The articles may have a length considerably greater than their width or their height, in particular flat boxes with width considerably less than the height. However, the feeding system may work also with articles having width greater than the height.  
         [0017]     The articles are preferably supported in the pallet with their height essentially vertical. The article may be a stack of sheets, such as glass sheets.  
         [0018]     The stack of sheets may be encased in wooden or another case.  
         [0019]     Among the advantages of the feeding system of the present invention are:  
         [0020]     saving space owing to the unique transverse disposition of the two railways;  
         [0021]     accurate positioning of the pallets/articles on the carriages and in the processing machine;  
         [0022]     creating a stock of articles on the additional supply stands for flexible synchronization of the supply rate of articles with the processing rate of the processing machine;  
         [0023]     effective use of only two carriages for moving, stocking and feeding pallets with articles;  
         [0024]     automation of the feeding process;  
         [0025]     the arrangement is simple, modular and allows adding more components by simply extending the railway or building more crossroads.  
         [0026]     In accordance with another aspect of the present invention, there is provided a strapping machine for strapping articles by placing a strap about an article, tensioning and bonding the strap in a closed loop lying substantially in one strapping plane. The article has a first and a second transverse axes and dimensions in the strapping plane. The machine comprises a first carriage carrying a strapping head, adapted to move along the first axis and to transport operatively the strapping head from an initial position remote from the surface of the article to a first contact position with the surface, so that the strap can be tensioned about articles with varying first dimension.  
         [0027]     The machine further comprises a second carriage movable along the second axis and adapted to support the strap and to transport it from an initial position remote from the surface of the article to a second contact position with the surface, so that the strap can be tensioned operatively about articles with varying both first and second dimensions.  
         [0028]     The machine may further comprise a third carriage movable in the strapping plane and adapted to transport a portion of the strap from an initial position remote from the surface of the article to a third contact position with the surface, thereby ensuring more precise positioning of the strap on the article.  
         [0029]     Preferably, the first axis is approximately horizontal and the second axis is approximately vertical.  
         [0030]     The machine as a whole may be adapted for limited motion along an axis perpendicular to the strapping plane, for example, by a pneumatic cylinder. Thus, two or more adjacent straps can be placed on the article in one transport cycle by simply displacing the machine along the length of the article.  
         [0031]     The strapping machine of the present invention provides for rapid and reliable strapping of articles along a contour with two variable dimensions (width and height) without any adjustment. The positioning of the contour along the third dimension (length) of the article may be provided by the motion of the transport carriage, so in fact the strapping machine is capable of operatively strapping any sequence of articles with all three dimensions varying from article to article. Moreover, a single article with varying contours of strapping along its length may be strapped as well, for example a stepped shape or tapered shape.  
         [0032]     The strapping machine also provides for more accurate positioning of the straps on the article—about 5 mm tolerance or better. Thus, the following risks can be avoided or minimized:  
         [0033]     jamming of the strap in the strapping head and damage to the article or machine;  
         [0034]     tearing of straps while transporting a box to the warehouse and damaging the box, especially breaking of a strapped wooden frame with glass sheets.  
         [0035]     Furthermore, the outer appearance of the accurately strapped articles is more aesthetic and commercially appealing.  
         [0036]     The usage of the feeding system of the present invention with the strapping machine of the present invention is especially advantageous. The feeding carriage provides accurate positioning of the article, about 5 mm, so that the article can be strapped directly on the carriage, without further adjustment with respect to the strapping machine. This is important for sensitive, fragile and slippery objects such as glass sheets. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]     In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:  
         [0038]      FIG. 1  is a schematic layout of the feeding system of the present invention;  
         [0039]      FIG. 2  is a side view of a feeding carriage used in the feeding system of  FIG. 1 ;  
         [0040]      FIG. 3  is a sectional view of the feeding carriage of  FIG. 2  and a crossroads stand;  
         [0041]      FIG. 4  is a schematic elevation view of the strapping machine of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0042]     With reference to  FIG. 1 , the feeding system  10  of the present invention comprises a supply railway  12  and a feeding railway  14  intersecting at a crossroads  16 , a supply carriage  18 , a feeding carriage  20 , a supply (loading) stand  22  and a crossroads stand  24 . Optionally, the system may have an unloading stand  26  and a plurality of additional supply stands  32   a ,  32   b , . . .  32   n  and  34 , etc. A computerized control system (not shown) including positional sensors, velocity sensors, load sensors, etc. controls the operation of the carriages  18  and  20 .  
         [0043]     The feeding system  10  is used for inserting (feeding) and positioning stacks of glass sheets  40  supported on pallets  42  in a strapping machine  44 . The stacks are typically flat, e.g. their width is considerably less than their length and height (the length and the width are seen in the plan view of  FIG. 1 ). The stacks are encased in wooden cases or frames embracing their width.  
         [0044]     The strapping machine  44  requires feeding along the axis Y in  FIG. 1  and performs strapping along a contour lying in a plane perpendicular to the axis Y. Consequently, the feeding railway  14  extends along the axis Y. The supply railway  12  is perpendicular to the feeding railway  14 . The crossroads  16  provides free passage of the carriages  18  and  20  along their respective railways  12  and  14 .  
         [0045]     With reference also to  FIG. 3 , the crossroads stand  24  comprises four pillars  50 . Each pillar has a landing pad  52  with guides  54  designed and disposed for receiving the pallet  42  in a position where the pallet bridges both railways  12  and  14 . The pillars  50  allow both carriages  18  and  20  to pass therebetween.  
         [0046]     The supply stand  22  comprises four pillars  60  with landing pads and guides similar to those in the crossroads stand. However, the pillars  60  are designed to position the pallet  42  bridging only the supply railway  12 , and to allow passage of the supply carriage  18 .  
         [0047]     The additional stands  32  and  34  have similar design to the supply stand  22 . The unloading stand  26  is similar to stands  22  or  32  but allows passage of the feeding carriage  20 .  
         [0048]     The feeding carriage  20  comprises a chassis  70 , wheels  72  and  73 , electric drives  74 , a lifting platform  76 , a cable  78  in articulated shield, a controller  80 , position and speed sensors (not shown). The chassis  70  has two lifting jacks  81  for raising the platform  76  that are powered synchronously by a motor  86  via gears and transmission shaft  88 . The platform is also supported in four linear bearings  82 . The platform  76  has guiding cones  84  adapted to enter corresponding recesses  85  in the pallets  42  for alignment of the latter.  
         [0049]     The lifting platform  76  and the chassis  70  are designed such that when the platform is in lowered position, the feeding carriage  20  can freely pass under the pallet  42  resting in one of the stands  24  or  26 . In a raised position, the platform  76  lifts the pallet  42  clear above the landing pads  52  and their guides  54  so that the carriage  20  can carry the pallet  42  through the same stands.  
         [0050]     The supply carriage  18  has a lifting platform  96  and other elements similar to those of the feeding carriage  20  except that their dimensions may differ in accordance with the gauge of the railway  12  and the size of the stacks  40 . Consequently, the construction of the carriage  18  and its lifting platform enables free passage of the carriage under the pallet  42  resting on the stands  22 ,  24 ,  32  and  34  and free transport of the pallet  42  above the landing pads of the same stands.  
         [0051]     The feeding system  10  operates in the following way. An external transport means such as forklift truck  90  brings a pallet  42  with a stack of glass sheets  40  from the production line and leaves it on the supply stand  22  over the supply railway  12 . Guides  54  provide for an accurate positioning of the pallet on the landing pads  52 . The supply carriage  18  comes along the same railway with its platform  96  lowered and stops under the pallet  42 . The platform  96  is then raised and the pallet  42  is lifted off the landing pads  52 . The supply carriage  18  carries the pallet  42  to the crossroads stand  24 , stops therein and lowers the platform  96  leaving the pallet  42  on the landing pads  52 . Then the supply carriage  18  runs back to the supply stand  22  for another pallet.  
         [0052]     The feeding carriage  20  comes along the feeding railway  14  with its platform  76  lowered and stops under the pallet  42  in the crossroads stand  24 . The platform  76  is then raised and the pallet  42  is lifted off the landing pads  52 . The feeding carriage  20  carries the pallet  42  to the strapping machine  44  and positions the pallet  42  with the stack  40  in a predetermined position or positions for strapping. After the strapping is done, the carriage  20  travels further down the railway  14  to the unloading stand  26 , stops therein and lowers the platform  76  leaving the pallet  42  on the landing pads. Then the feeding carriage  20  runs back to the crossroads stand  24  for another pallet  42  which, in the meantime, had been fetched by the supply carriage  18 .  
         [0053]     The strapped stack  40 ′ with its pallet  42  is collected by a forklift truck  90 ′ from the unloading stand  26 .  
         [0054]     If, for some reason, the stacks  40  are coming from the production line with greater rate than the strapping machine can handle, the additional stands  32  may be used for accumulating stock in the following way. The supply carriage  18  takes a pallet  42  from the loading stand  22  but the control system finds that the crossroads stand  24  is still busy. The carriage  18  is directed to leave the pallet  42  on the additional stand  32   n  (the nearest to the crossroads stand  24 ). The next pallet  42  is then left on the stand  32   n - 1 , etc. When the crossroads stand  24  is freed, the carriage  18  can take the pallet from the stand  32   n  and put it on the stand  24 , and so on.  
         [0055]     The additional stand (or stands)  34  may be also used for accumulating stock while the crossroads stand  24  is still free. Another option is to use the stand  34  for performing a technological operation such as assembling a frame or case over the stack of glass sheets  40 .  
         [0056]     Alternatively, the railway  12  may be equipped with a second loading stand at the side of the additional stand  34 , and possibly with a second supply carriage  18 . In such case, pallets  42  may be fed to the strapping machine  44  with doubled rate. Furthermore, another feeding railway with another crossroads stand and another strapping machine may be added.  
         [0057]     It will be appreciated that the inventive feeding system allows construction of various configurations appropriate to the needs of the production process. Moreover, each such configuration even once built, is rather flexible and can cover wide range of packaging dimensions and production rates. The system also can be easily reconfigured by adding or removing modules such as stands, carriages, feeding railways and strapping or other packaging machines. The system can be used for feeding other processing machines such as washing, painting, coating, shrink-wrap, bottling, filling machines, etc.  
         [0058]     With reference to  FIG. 4 , there is shown a schematic elevation view of the strapping machine  44  of the present invention. The stack  40  to be strapped is shown on the feeding carriage  20  with all its parts numerated as above.  
         [0059]     The strapping machine  44  comprises a vertical portal frame  102 , a vertical carriage  104 , a lateral carriage  106 , a bayonet assembly  108 , a strap feeder  110  and a control desk (not shown).  
         [0060]     The portal frame  102  is disposed over the feeding railway  14  in a plane perpendicular thereto. The frame  102  is supported on wheels  111  rolling along guides  112  parallel to the feeding railway  14 . Pneumatic drives  113  provide limited reciprocating displacement of the frame  102  along the guides. The frame  102  further has chutes  114 ,  116  for conducting packaging strap  120 .  
         [0061]     The vertical carriage  104  has a drive  122  with transmission located in the frame  102 , sensors for detection the height of the stack  40  and chutes  124 ,  126  for conducting the strap  120 . The vertical carriage  104  is adapted to travel vertically along the portal frame  102  and to bring the strap  120  into contact position with the surface of the stack  40 .  
         [0062]     The lateral carriage  106  also has a drive (not shown), a strapping head  134  and sensors for detection the width of the stack  40 . The lateral carriage  106  is adapted to move along a slightly inclined axis X 1  and to transport the strapping head  134  to a contact position with the lateral surface of the stack  40 .  
         [0063]     The bayonet assembly  108  comprises a bayonet  140  and a drive (not shown) for pulling the strap  120  across the portal opening. In extended position, the end of the bayonet with the end of the strap is received in the chute  116  of the frame. In retracted position of the bayonet  140 , the feeding carriage  20  is free to travel along the railway  14  in or out of the strapping machine  44 .  
         [0064]     The strapping head  134  comprises a tensioning device  144  and a bonding device  148 .  
         [0065]     Optionally, a third carriage (a second bayonet assembly)  152  may be positioned opposite to the lateral carriage  106 , at the other side of the stack  40 . This bayonet is adapted to transport a portion of the strap (a loop)  154  into a third contact position with the stack  40  and is similarly equipped with sensors for detecting the opposing surface of the stack  40 .  
         [0066]     The strapping machine  44  operates in the following way. Initially, the vertical carriage  104  is in uppermost position, the lateral carriage  106  and the bayonet assemblies  108  and  152  are withdrawn so that the portal frame  102  is not obstructed. The feeding carriage  20 , carrying a pallet  42  with a stack  40 , enters the portal frame  102  along the feeding railway  14  and stops in a predetermined position with respect to the portal  102 . The bayonet  140  moves into the receiving chute  116  and the vertical carriage  104  moves down until its sensor detects the stack upper face so as to bring the strap in contact with the upper stack surface. At this time, the strapping head feeds the strap  120  through the bayonet  140  across the portal  102  into the receiving chute  116  and pushes it further through the chutes  114 ,  126 ,  124  back to the strapping head  134 . There the strap end is caught, and then the strapping head  134  slides slowly until it touches the surface of the stack  40 . The system automatically detects the width of the stack by means of a mechanical flap and a sensor. Simultaneously, the second bayonet  152  (if installed) pulls a loop  154  of the strap towards the surface of the stack  40 . During the motions of the carriages, the tensioning device  144  takes up the slack of the strap  120  back to the strap feeder  110 .  
         [0067]     When the strapping head  134  establishes contact with the stack  40 , the tensioning device  144  further pulls the strap  120  stronger so as to pull it out of the chutes and tightens the loop about the stack  40  with predetermined tension. Finally, the bonding device  148  bonds the strap loop and cuts the loop off the strap end. The vertical carriage  104 , the lateral carriage  106  and the bayonets  140  and  152  return to their initial positions.  
         [0068]     If more than one strap loop has to be tightened on the stack  40 , the pneumatic drive  113  is operated to displace the portal frame  102  a small fixed distance and another strapping cycle is performed as described above.  
         [0069]     The feeding carriage  20  then may move to another position for strapping or may carry away the strapped stack.  
         [0070]     It will be appreciated that the strapping machine  44  allows quality strapping of stacks or boxes with three variable dimensions without interruption for readjustment. For example, in a glass production factory, such machine straps stacks of glass sheets in variety of sizes, from 450×1000 mm to 2800×3800 mm, where the width of the stack (thickness) may vary between 120 and 900 mm.  
         [0071]     Although a description of specific embodiments has been presented, it is contemplated that various changes could be made without deviating from the scope of the present invention. For example, the strapping machine may be modified for strapping in a horizontal plane, the strapping head may be carried by the vertical carriage instead of the lateral, drives may be hydraulic or electric, etc.