Strapping machine

Abstract: A strapping machine (10) is provided with a restriction device (16) that helps prevent strapping material (15), remaining after a break in the material, from being drawn, by gravity or inertia, into the strapping machine slack box. The restriction device (16) also assists in the orderly movement of strapping material (15) through the strapping machine, by being adjustable, by either strap tension or weight, to widen or restrict the strap path as needed.

Description: Strapping machines comprise a number of elements that allow for a strap to be fed from a reel to a strapping head and then onto an object to be strapped. Within the strapping machine the strapping material must be fed through a number of elements that allow the strapping material to travel quickly, efficiently, and accurately towards an object to be strapped. In the operation of strapping machines the strap is first propelled in a forward direction towards the item to be strapped and then the strap is pulled around the item and tightened. Means are provided to reverse the direction of strap travel so that strap may be tightened about the object prior to cutting the strap and so that cutting and securing strap can be accomplished with little waste of material. Strap pulled back into the machine during the tightening process is subsequently released, within the strap path, for further strapping. However, because strap can double up when released, which may result in a restriction of its movement, use of these complex strapping machines is often times impeded by a blockage of loose strap. Because of the nature of the strapping material, and the need for the material to move rapidly through the strapping machine, no single element of these machines generally holds the loose end of the strapping material within the strapping machine. In some present strapping machines, upon the breaking of an end of the strapping material, the leading end of the strap which is left in the strapping machine is subjected to the pull of gravity and inertia during takeup and little, if any, restraint. The strap end, therefore, often falls or coasts from the guiding members of the machine into the slack box of the machine. This action is known as "suck-back" by users of strapping machines. When suck-back occurs, the end of the reel must be retrieved and the strapping machine must be re-threaded. This process is time consuming and causes delays in the strapping process. Previously, a fixed type of restrictor has been tried in certain strapping machines. The fixed restrictors, which have been placed between the strap gate and the winder (or strap tensioning device) have proven to be effective in preventing suck back, but also simultaneously restrict strap, which is not broken or loose, from proceeding in the strap path after certain normal machine operations. For example, after an unwinding (a common event in a strapping cycle), strap may form a "tear drop" shaped loop. In a machine with a fixed restrictor, strap material in the shape of a tear drop may be prevented from passing through the fixed restrictor because of the inherent doubling up of the thickness of the strap in such a loop. Further, a fixed restrictor may prevent loops of strap from pulling out of the slack box and into the head, for similar reasons. According to the present invention, a strapping machine, including a winder; a strap gate, disposed operationally apart from said winder; a slack box; and, a restriction device between the winder and the strap gate is characterised in that the restriction device comprises: an upper guide, having a first end and a second end; a lower guide having a first end and a second end said first end of said lower guide being rotationally connected to said first end of said upper guide; and, means biassing said upper guide and said lower guide apart such that said second end of said upper guide is urged apart from said second end of said lower guide, with said second end of said upper guide being disposed towards said winder and said second end of said lower guide being disposed towards said strap gate in a default position, to restrict the size of the gap between said strap gate and said winder, in use, to prevent strapping material from falling or coasting into the slack box. Further, preferably the ends of the upper and lower guide form a strap path which provides a frictional surface on which the strap may drag to slow down the falling or coasting of the strapping material into the slack box. As the guides are spring biased the movement of strap, respectively, beneath or above the lower and upper guide, can change the position of the guides depending on the tension and force applied to the guides by the strap. The lower guide, when forced upward by strap, provides less of a restriction for the strap to travel through allowing for quicker strap speeds. When the upper guide is forced downward by strap, the restriction device provides less restriction below the winder, allowing quicker clean up of looped material. For example, the formation of a loop of material, due to any number of causes, including the winding and subsequent unwinding of strapping material, may cause the upper guide to be forced downward. When the upper guide is forced downward less restriction occurs for strap passage between the guide and the winder, allowing the loop of strap to be more quickly pulled out of the machine. Similarly, a loop between the lower guide and the strap gate is more quickly removed when the guide is forced upward by the strap. In one embodiment of the present invention the lower guide is divided into two sections along its longitudinal axis and the upper guide is rotationally set between the two sections of the lower guide and attached to a strapping machine. The lower guide sections and the upper guide are biased apart at their second ends by a spring such that the upper guide is disposed upward and the two sections of the lower guide are disposed downward. In this manner strap which may travel laterally along the strapping gate, may be more easily guided by the two separate parts of the lower guide. Particular embodiments in accordance with this invention will now be described with reference to the accompanying drawings; in which:- Figure 1 is a front elevation of a strapping machine showing a restriction device in a first default position; Figure 2 is an enlarged front elevation of the restriction device; Figure 3 is an elevation of the strapping machine showing the restriction device in a second position; Figure 4 is an enlarged front elevation of the restriction device; Figure 5 is an elevation of the strapping machine showing the restriction device in a third position; Figure 6 is an enlarged front elevation of the restriction device; Figure 7 is an elevation of the strapping machine showing the restriction device in a fourth position; Figure 8 is an enlarged front elevation of the restriction device; and, Figure 9 is a perspective view of another embodiment of the restriction device. Referring to the drawings, Figures 1 and 2 show a strapping machine 10 having a winder 12 and a strap gate 14 in a first strapping position with strapping material 15 being fed through strapping machine 10. A restriction device 16 comprising an upper guide 18 and a lower guide 20 is provided. Upper guide 18 and lower guide 20 are rotationally connected by pin 22 at a first end 18a and 20a, respectively, to each other and to the strapping machine 10 through wall 11. The second ends of guide 18 and 20, upper guide end 18b and lower guide end 20b, of restriction device 16 are biased apart by a spring (not shown). In a default, at rest position, upper guide 18 is biased upward and upper guide end 18b is disposed generally toward winder 12 and lower guide 20 is biased downward and lower guide end 20b is disposed generally toward strap gate 14. In this first default position, strapping material 15 is fed through strapping machine 10 under constant tension, putting little or no pressure on restriction device 16. As a result, the biasing spring of restriction device 16 is the prevalent force on the upper guide 18 and lower guide 20 of restriction device 16, biasing upper guide end 18b and lower guide end 20b apart and toward, respectively winder 12 and strap gate 14. Restriction device 16 thereby closes the gap 17 between winder 12 and strap gate 14 so that strapping material 15 proceeds from strap gate 14 through to winder 18 utilizing guide ends 18b and 20b as additional guidance between these elements. Referring now to Figures 3 and 4, strapping machine 10 is shown with the leading edge 24 of strapping material 15 in a position between feed wheels 26 and tension wheels 28. Restriction device 16, in its first default position, as shown in Figures 1 and 2, has lower guide 20 and upper guide 16 biased apart, filling gap 17. Lower guide 20b of restriction 16 in conjunction with strap gate 14 provide a drag on strapping material 15 such that the leading edge 24 of the strapping material is stopped from slipping or coasting through feed wheels 26 down to the slack box (not shown). Such a slip, also known as a "suck back" is thus prevented by restriction device 16 of the present invention. Thus, in Figures 1 through 4, the default position of restriction device 16 is shown to provide a path for strapping material 15 proceeding normally through the strapping machine 10 and to provide a means for stopping the slippage of strapping material 15 into the slack box. Suck back, which requires that the strapping process cease and that strapping material 15 be re-threaded into strapping machine 10, is thus generally eliminated. The improvement over fixed restriction devices of the prior art is shown in the ability of restriction device 16 to provide guidance for strapping material 15 and prevent suck back, while allowing the flexibility of allowing feeding of strapping material 15 after unwinding and when an excess of slack strapping material has accumulated in the slack box, both common events. In these conditions, as explained below, lower guide 20 may be pushed upward and upper guide 18 may be pushed downward, by the force of strapping material 15, to open gap 17 as needed to alleviate strap drag that causes jams. Referring now to Figures 5 and 6, strapping machine 10 is shown having an excess of strapping material 15 in a slack box (not shown) and below and about strap gate 14 and winder 12. In such situations, strapping material 15 is not fed through strapping machine 10 under constant tension. Strapping material 15 may tend to push upward on lower guide end 20b, forcing the lower guide to be pushed upward providing a larger gap 17, reducing feed force requirements and providing a means to eliminate the slack without entanglement of the strapping material 15. In another situation, as illustrated in Figures 7 and 8, after strapping material has been fed through the head (not shown) of strapping machine 10, and placed around an object to be strapped, the tension wheels 28 of the strapping machine 10, in association with winder 12, cause the free end of the loop of strapping material 15, around the object to be strapped, to be pulled into strapping machine 10 tightening the strapping material 15 about the object to be strapped. After the ends of the strapping material are fastened together, in a manner known in the art, the strapping material 15 is cut, the winder 12 unwinds to allow the rewound material to subsequently be used to strap the next item to be strapped. Feed wheels 26 begin to feed the strapping material again towards the head (not shown). Concurrently, new strapping material 15 has continued to be fed towards strap gate 14 and has collected in the slack box (not shown). Loops of strapping material 15, as shown in Figure 8, are thereby formed above and below restriction device 16. The presence of these loops, or "tear drops", of strapping material force upper guide 18 to be disposed toward the lower guide widening gap 17. In this manner restriction device 16 has its lowest profile allowing for the freer flow of strapping material 15 such that local jamming incidents are reduced or generally eliminated. It is to be understood that variations of the shape and size of restriction device 16 may be made. For example, in the preferred embodiment of the present invention, shown in Figure 9, a restriction device 29 having a three guiding members, one upper guide 30, for engagement with winder 12 sandwiched between two lower guides 32 and 34, for engagement with strap gate 14 are shown, rotationally engaged together, at a first end, by a pin 36 and biased apart by a spring (not shown), in a manner similar to that described above. The use of two lower guides 32 and 34 allows for guidance under conditions of wide lateral movements of strapping material through strap gate 14.

Claims: A strapping machine including: a winder (12); a strap gate (14), disposed operationally apart from said winder; a slack box; and, a restriction device (16) between the winder (12) and the strap gate (14); characterised in that the restriction device (16) comprises: an upper guide (18), having a first end (18a) and a second end (18b) a lower guide (20), having a first end (20a) and a second end (20b), said first end (20a) of said lower guide (20) being rotationally connected to said first end (18a) of said upper guide (18); and, means biassing said upper guide (18) and said lower guide (20) apart such that said second end (18b) of said upper guide (18) is urged apart from said second end (20b) of said lower guide (20), with said second end (18b) of said upper guide (18) being disposed towards said winder (12) and said second end (20b) of said lower guide (20) being disposed towards said strap gate (14), in a default position, to restrict the size of the gap between said strap gate (14) and said winder (12), in use, to prevent strapping material from falling or coasting into the slack box. A strapping machine according to claim 1, wherein said second end (18b) of said upper guide (18) and said second end (20b) of said lower guide (20) define a frictional surface which engages the surface of the strapping material, in use, to slow down falling or coasting strap material. A strapping machine according to claim 1 or 2, wherein said lower guide (20) is forced up or the upper guide (18) is forced down, in response to the strap material being positively driven to provide a reduced restriction and thereby to prevent jamming of strap material. A strapping machine according to any one of the preceding claims, wherein said lower guide is comprised of two parts (32,34), said upper guide (30) being rotationally attached between said two parts (32,34) of said lower guide at said first end. A strapping machine according to any one of the preceding claims, wherein said upper guide and said lower guide are biased apart by a spring.

Inventors: BOBREN ALLEN J, BOBREN, ALLEN J.
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 2001
Main classification: B65B13
IPC codes: B65B13