OBJECT-TURNING APPARATUS FOR A HIGH-SPEED STRAPPING MACHINE

Technical Field

This invention pertains to strapping machines and, more particularly, to devices for rapidly and accurately rotating a strapped object ninety degrees for placement of a cross-strap around the object.

Background Art

It is frequently advantageous to place a second strap on an object, such as a bundle of newspapers, at right angles to the first strap. Heretofore, rotating the object often has been done at a station remote from the strapping station since it is difficult to fit the necessary rotating components into the highly complex machinery of the strap¬ ping apparatus. U.S. Patent 3,901,138 shows a typical bundle-rotating device remote from a strapping station. The disadvantage with this type of bundle-rotating device is that it requires moving the bundle out of the strapping sta¬ tion for the purpose of rotating the bundle.- This movement of the bundle requires considerable time and defeats the purpose of high-speed strapping machines in which the bundle is delivered to the strapping station and removed at ex¬ tremely high rates of speed and the straps are placed on the bundle at the strapping station in less than a second. A strapping machine capable of doing such rapid strapping and movement of the bundle into and out of the strapping sta¬ tion, for example, is shown and described in U.S. Patents 4,120,239 and 4,201,127 (the subject matter of both patents being incorporated by reference into this description) .

Other known types of rotating apparatus are shown in U.S. Patents 2,850,963 and 3,783,773. Both devices are complicated in operation and require a considerable amount of time for rotating the object to be strapped. In particular, the structure of U.S. Patent 2,850,963 requires

rotation of the object, followed by repositioning of t object, which, during its initial rotation, can be skew out of proper alignment on the conveyor. Furthermore, t delivery to and removal from the strapping station i cumbersome and time consuming.

Another machine uses a pair of opposed pushe which engage opposite sides of the object at forward an rearward halves and rotate the bundle directly on the con veyor, which has a relatively slippery surface for this pu pose. Rotation by the use solely of these opposed pusher is slow. This type of machine is also limited in its abili ty to convey a bundle rapidly.

Disclosure of Invention This invention provides a bundle-turning devic which is simple in operation and useful at a strappin station on a high-speed strapping machine. The devic simultaneously rotates and positions a bundle or stack a a strapping station. It is especially useful at a statio which carries the object on a rapidly accelerated high friction conveying surface to a strapping station.

Basically, the device operates by moving th object to the strapping station on a high-speed, high friction conveyor, lifting the object off the high-frictio surface onto a low-friction surface, extending vertical opposed turning posts or bars to move simultaneously agains opposite, transversely spaced sides at opposite halves o the object, and rotating the object ninety degrees against positive stop, which is either a part of the turning post o an independent post. The stop provides tr iangulation o three-point engagement on the bundle to assure that th bundle can be rotated at maximum rotational velocity at th end of its turn, yet stop in the correct orientation fo strapping. Maintaining maximum rotational velocity through out the turn assures that the output requirements of th strapping machine are not slowed by the turning operation.

In its broadest aspect, the turning mechanism als has application on other types of lower friction conveyin

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surfaces or turning surfaces where speed of delivery into and out of the strapping station is not a high priority. It is most uniquely suited, however, to the combination with the lifting table of a low-friction surface to obtain the maximum benefits of high conveying speed and rotational speed for a strapping machine of the type capable of handl¬ ing 60 bundles per minute through the strapping station.

Brief Description of Drawings Figs. 1A-1F are. schematic operational diagrams illustrating the rotation sequence of an object, such as a stack of newspapers, in a strapping machine.

Fig. 2 is a schematic isometric illustrating a mechanism capable of carrying out the functional operations of Figs. 1A-1F and embodying the principles of the inven¬ tion.

Fig. 3 is a perspective of a typical strapping machine embodying the principles of the invention.

Figs. 4A-4E are schematic operational diagrams of an alternate embodiment of the invention.

Fig. 5 is a detailed partial top plan of the alternate embodiment of this invention.

Fig. 6 is a partial side elevation of an alternate embodiment of this invention. Fig. 7 is another detail similar to Fig. 5 showing the turning post rotated ninety degrees.

Best Mode for Carrying Out the Invention

As is best shown in Figs. 2 and 3, a high-speed strapping machine of the type shown in U.S. Patents 4,120,239 and 4,201,127 is illustrated. In this type of equipment, an object is conveyed by a conveyor mechanism 10 to a strapping station 12 in which a strap or wire SI is placed around the object or bundle B. At the strapping station, a turning apparatus 16 rotates the bundle ninety degrees and a second strap S2 is applied to the bundle. Finally, the conveyor 10 then moves the cross-strapped bundle out of the strapping apparatus.

The strapping apparatus at the strapping stati includes a guide 14 which identifies the location of th strap line for the purposes of this invention. It should understood that suitable strapping apparatus constructed i accordance with the teachings of U.S. Patent 4,120,239 an identified schematically by reference numeral 20 delivers bundle against stops 60, 61 to the strapping station 12 feeds a plastic strap around the bundle at the strappin station, compacts the bundle, if desired, tensions the stra tightly around the bundle, and finally, seals the tensione strap on the bundle. A second strap may be fed into th strapping guide 14 prior to final sealing of the previou strap. Reference is made to this feeding of the secon strap only as a point of reference to aid understanding th sequence of operations of the bundle-rotating mechanism o this invention.

The strapping station uses conveying mechanism and a hold-down bar 21 of the type shown in U.S. Paten 4,201,127 (which is incorporated by reference herein). Th conveying mechanism includes an upstream, transversel spaced set of conveyors 22, having a high-friction conveyin surface which will grip the bottom of the bundle for rapidl accelerating the bundle. A similar second set of trans versely spaced conveyors 24 are located downstream from th upstream conveyors 22 for rapidly accelerating the bundl out of the strapping station. As is well understood, thes conveyors are driven simultaneously by a suitable motor 2 and drive 24a.

A turning apparatus 16 is best illustrated in Fig 2 and includes two spaced, vertical turning posts or bars 2 and 30. The posts are spaced lengthwise of the conveyor slightly greater distance than the width of the bundle to b turned and are adjustably positioned so as to be adjuste for various bundle widths. The posts are secured to a com mon cable 30a which is powered through a turning cylinder 3 to move the posts simultaneously. The posts are positione to engage simultaneously opposite, laterally facing sides o the bundle at respective forward and rearward halves of th

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bundle relative to the length of the bundle so that by push¬ ing against the laterally facing sides, the bundle is rotat¬ ed through ninety degrees to the position shown in Fig. IE. As the bundle rotates, an independent vertical stop post 34 becomes positioned against the same lateral side as the post 30, and thus is in alignment with the post 30. The three posts 28, 30 and 34 provide a triangulation or three-point engagement orientation on the bundle, bringing the bundle to a rapid stop in position for strapping. The stop post 34 is initially moved by a spring 36 against the post 30 (Fig. IB) when the post 30 is moved by the turn cylinder 32. The spring 36 and block 38, however, limit the movement of the stop post 34 so that it becomes positioned as shown in Fig. IE. The stop post is automatically retracted by post 30 as the post 30 is returned during a reverse stroke of the turn cylinder 32, as is shown in Fig. IF.

A low-friction lifting mechanism 40 includes a downstream table 42 which is lifted 'by a cylinder 44 and an upstream table 46 which is lifted by a cylinder 48. The cylinders 44, 48 and 32 are preferably pneumatically power¬ ed. The space between the tables allows straps to be applied to the bundle.

In operation, the conveying mechanism 10 delivers the bundle to the strapping station, where it is stopped by posts 60 and 61 of the type shown in Patent 4,201,127. The first strap or straps are applied. The air cylinders 48 are energized at a time just prior to sealing of the first strap, with a convenient time being selected as the initia¬ tion or feeding of a new strap into the strap guide 14. By the time the first strap has been completely sealed and is free to be moved with the bundle, the lifting tables 42 and 46 will begin to rise and lift the bundle. The bundle is lifted off the conveying surfaces and totally supported by the tables 42 and 46. The air pressure buildup in the cyl- inders 44 and 48 indicates that the tables are fully raised, and triggers the energization of turn cylinder 32 so that both turning posts 28 and 30 are moved against the object, as shown in Figs. 1A and IB. The stop post follows into the

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position shown in Fig. 1C and the bundle is fully rotate into the position shown in IE.

A limit switch 62 on the turn cylinder signals th completion of rotation and immediately energizes the pneu matic supply to return the turn cylinder to its origina position and to lower the tables 40 and 42. At this time the bundle is back on the conveying surfaces 22 and 24, an the cross-strap is applied. After the cross-strap is ap plied, the bundle is removed by energizing the conveyors 2 and 24.

When tying bundles of newspapers having adver tising inserts, the bars are elongated to resemble paddle 100 and 102 (as shown in Figs. 4A-4E). The elongated bar provide larger surface area of contact on the spaced, les packed edges of the papers in the bundle. That is, th broad face of each paddle contacts a larger area of th bundle, better insuring contact with a firm part of th bundle. In other respects the turning device is similar t that just described, except that the longer surface of th paddle integrally provides the three-point ^' stop for triangu lation or accurate positioning of the bundle. When th paddles retract to their starting position, they remai rotated until they nearly reach their destination.

Referring now to Figs. 6-8, each bar or paddle ha an oval-shaped shroud 106 fixed to a shaft 104. The shaf is fixed to the carriage 140 while the shroud 106 is abl to rotate relative to the shaft 104. The rotation of th shroud 106 is controlled with a slip clutch 108. The clutc may be set to a prescribed minimum force which need be at tained before the shroud 106 will rotate. The clutch 108 i attached to the shroud 106 through a cam plate 110. Pivot ally attached above the cam plate 110 in line with th clutch 108 is a forked cam 116 which swings with the rota tion of the paddle. A cam follower 112 extends downwardl from a triangular plate 114 which is rigidly attached t shaft 104. The follower 112 rolls between the forks of th cam 116 as cam plate 110 and the paddle turn relative t triangular plate 114 and shaft 104. A stop surface 11

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projects upwardly from the plate 110 and contacts a stop 120, which projects downwardly from plate 114, to insure that the shroud 106 only rotates ninety degrees. When fully rotated, the paddle serves as a stop. Because it contacts both halves of its side of the bundle, the tr iangula tion orientation is maintained.

To insure that the paddle rotates substantially ninety, degrees where the bundle is not of sufficient strength to rotate the paddle, a cam surface 122 is posi- tioned on the frame to engage a wear strip 126 on the plate 110 as the paddle moves inwardly. When the carriage 140 returns to its starting position, a cam surface on the plate 110 contacts a reset roller 128 to return the paddle coun¬ terclockwise to its original position. Only when the reset roller is engaged will the shroud 106 begin to turn, the slip clutch 108 otherwise maintaining the paddle in its turned orientation. Cam surface 124 is positioned to con¬ tact the other paddle 102.

While preferred embodiments of the invention have been shown and described, it should be understood that vari¬ ations will be apparent to one skilled in the art, and thus the invention is not to be limited to the specific embodi¬ ments illustrated in the drawings. For example, a second stop post can be added adjacent the turning post 28 for four-point positioning.