US3552305A

US3552305A - Tensioning apparatus

Info

Publication number: US3552305A
Application number: US753242A
Authority: US
Inventors: John Dorney; Colin Robinson
Original assignee: POWER IND Ltd
Current assignee: POWER IND Ltd
Priority date: 1967-08-16
Filing date: 1968-08-16
Publication date: 1971-01-05
Anticipated expiration: 1988-01-05
Also published as: DE1786101A1; NL6811727A; GB1235116A

Abstract

In a package binding machine for use with synthetic resin binding material, there is incorporated a primary tensioning device adapted to draw a loop of tape onto a package and to apply a small initial tension to the tape, and a secondary tensioning device adapted to apply a final tension to the tape and arranged to repeat its tensioning stroke any number of times necessary to bring the loop to a required final tension.

Description

United States Patent John Dorney;

Colin Robinson, Berkshire, England 753,242

Aug. 16, 1968 Jan. 5, 1971 Power Industries limited Berkshire, England a British company Aug. 16, 1967 Great Britain Inventors Appl. No. Filed Patented Assignee Priority TENSIONING APPARATUS 13 Claims, 2 Drawing Figs.

US. Cl. 100/4, 100/32,100/-33; 156/73 Int. Cl B65b 13/22 Field of Search 100/4, 26, 29, 30, 31, 32, 33; 156/73 [56] References Cited UNITED STATES PATENTS 3,146,695 9/1964 Van De Bilt 100/4 3,157,109 11/1964 Flanigan etaL. 100/26 3,179,038 4/1965 Mackenzie 100/26 3,183,824 5/1965 100/4 3,232,217 2/1966 IOU/26X 3,331,312 7/1967 Leslie 6! 31.... IOU/33X 3,442,203 5/1969 Kobiella 100/26 Primary Examiner-Billy J. Wilhite AtrorneyScrivener, Parker, Scrivener and Clarke ABSTRACT: In a package binding machine for use with synthetic resin binding material, there is incorporated a primary tensioning device adapted to draw a loop of tape onto a package and to apply a small initial tension to the tape, and a secondary tensioning device adapted to apply a final tension to the tape and arranged to repeat its tensioning stroke any number of times necessary to bring the loop to a required final tension.

62 139 413 8'615815 7'9iai7 6'3 67 13 PATENTED JAN 51% sum 1 0F 2 mm W 0 m. mm

TENSIONING APPARATUS SPECIFIC DESCRIPTION This invention relates to a improved package binding machine and more particularly to a package binding machine incorporating a new or improved tensioning apparatus.

In package binding machines a band of binding material is passed around a package to form a loop with overlapping ends, retracted to draw the loop against the package, tensioned, sealed by interconnection of the overlapping ends of the loop, and severed from the'binding material supply.

Hitherto it has been common practice to employ materials such as metal wires and bands in, packaging operations, and loops of these materials can be sealed by twisting together the overlapping ends in the case of wire binding material, or by means of a deformable metal seal which is placed around the overlapping ends and deformed to engage together and grip the overlapping ends.

In recent hears there has been a growing tendency to adopt synthetic resin tapes, particularly polypropylene tape, as binding materials. These materials while possessing many properties such as lightness, strength andcheapness which make them particularly suitable for use in packaging, nevertheless are inherently more susceptible to damage than the metallic -materials hitherto used, and in particular it is extremely difficult to seal loops of such materials with the conventional deformable metal seal without. damaging the tapes and consequently weakening the joint. This problem has however largely been overcome with the development of heat sealing and friction welding techniques by which processes the ends of the loop of tape are directly interconnected by a welding process without the use of a separate seal.

A further disadvantage of synthetic resin tapes as compared to metallic binding materials is the'undesirably high elasticity which they exhibit. Polypropylene tape, for example, may be extended by l 1 percent of its length when subjected to a tension of the magnitude normally applied in packaging operations, and it has been found that the tensioning apparatus in many existing packaging machines is not capable of accommodating itself to such a large extension. 7

According to our invention a package binding machine for use with synthetic resin binding materials incorporates tensioning apparatus comprising a primary tensioning device adapted to perform the function of drawing a loop of tape onto'a package and applying a small initial tension thereto,

and a secondarytensioning device adapted to apply the final tension to the tape, in which the secondary tensioning device operates through a limited stroke to tension the tape but is arranged to repeat its tensioning stroke a sufficient number of times to bring the loop to the required final tension, irrespective of the degree of extension-of the binding tape which may occur. Once the necessary tension has been applied the secondary tensioning device is halted and the tension is maintained while the ends of the loop are sealed together.'Thereafter the tension is released and the sealed loop is severed from the material supply.

In a preferred embodiment the tensioning apparatus is provided in an automatic or semiautomatic package binding machine adapted to utilize polypropylene tape binding material and to seal binding loops by friction welding the overlapping ends thereof.

One embodiment of our invention is illustrated in the accompanying drawings in which:

FIG. I is a partly-sectional elevation through a package binding machine incorporating tensioning apparatus in accordance with our invention; and

FIG. 2 is a sectional plan view on the line 2-2 of FIG. 1.

In the package binding machine illustrated in the drawings 10 is a casing which includes a primary tensioning device 11 and a secondary tensioning device 12. A base plate 13 of the casing 10 supports a frame 14 on which is carried, adjacent to the primary tensioning device 11 a free end gripper l5 fon'ned, adjacent to its lower end, with an aperture 15a. The

gripper 15 is pivotally connected to an intermediate point on a lever 16 one end of which is connected to a fixed pivot and the other end of which is connected to the piston rod 17 of a pneumatic cylinder G1. Extension or retraction of the cylinder G1 causes the gripper 15 to move away from or into gripping engagement with a nose plate 18 associated with the base plate 13.

On the opposite side of the frame 14, but aligned with the free-end gripper 12, is mounted a similar second gripper 19. The second gripper 19 is pivotally connected to an intermediate point on a lever 20 one end of which is connected to a fixed pivot and the other end of which is connected to the piston rod 21 of a pneumatic cylinder G2. Extension or retraction of the cylinder G2 causes the gripper 19 to move away from or into gripping engagement with the nose plate 18.

The construction, operation and arrangement of the nose plate 18 forms the subject matter of our copending Pat. application No. 753,241, tiled Aug. 16, 1968, now patented, and need not be further described herein.

The secondary tension device 12 comprises a pair of pneumatic cylinders ET mounted in side-by-side relationship on the base plate 13 and having piston rods 61 extending through apertures in support blocks 62 on the base plate 13. The piston rods 61 are connected to a support bracket 63 of generally U-shaped channel section which is movable with the piston rods 61 on extension or retraction thereof.

The bracket 63 supports a roller 67 and has a pair of upstanding lateral walls 68 between which two pulley wheels 69 are rotatably mounted in alignment with the roller 67.

The roller 67 and the pulley wheels 69 form part of the primary tensioning device 11 and are engaged by an endless flexible belt 70 which also passes around a drive pulley 71 connected to a reversible motor M, suitably an air motor. The belt 70 is tensioned by a pair ofjockey pulleys 72. Each jockey pulley 72 is rotatably mounted on the free end of an arm 73 pivoted to a fixed point adjacent to the axis of the drive pulley 71, and each jockey pulley 72 engages with a run of the belt 70 between the drive pulley 71 and one of the pulley wheels 69. The arms 73 are connected at intermediate points in their lengths by means of a tension spring 74 so that the jockey pul- Ieys 72 are at all times urged into engagement with the belt 70.

The bracket 63 supports, at its forward end, a tensioning gripper 75 pivotally mounted between the walls 68 and urged in a clockwise sense, as viewed in FIG. 1, by a torsion spring 76. The bottom face 77 of the gripper is arranged to engage a binding tape against the surface of the bracket 63. At the limiting position in the range of movement of the bracket 63, as shown in FIG. 1 and corresponding to maximum extension of the piston rods 61, an adjustable jack screw 78 carried by the tensioning gripper 75 isurged into engagement with a support block 79 by the torsion spring 76. In this position the bottom face of the gripper 75 is held clear of the bracket 63 and hence out of gripping engagement. As the bracket 63 is moved to the right from the FIG. 1 position the torsion spring 76 is effective to move the gripper 75 in a clockwise direction and into the gripping position.

The machine is adapted to receive polypropylene binding tape passed from .a supply and guided lengthwise of the bracket 63 between the belt 70 and the pulley 67, and under the tensioning gripper 75.

The primary tension device 11 also performs the function of feed and retraction of the binding tape, and when the motor M is driven in a forward direction the tape is gripped by the belt 70 and driven through the aperture 15a in the gripper 15, through the nose plate 18, and between the gripper 19 and the nose plate 18. The free end of the tape fed in this way is passed manually around a package to be bound or automatically around the package through a continuous track. The free end of the tape is then passed beneath the gripper l5 and once more through the nose plate 18, to a stop, thus forming a loop with overlapping ends.

A trip switch 81 provided at any convenient location is actuated by the tape during its travel to actuate the pneumatic cylinder G1 which in turn, causes the gripper to close and grip the tape against the nose plate 18.-The trip switch also reverses the motor M causing the belt 70 to be driven in the reverse direction to retract the tape drawing the loop against the package. When the desired primary tension has been applied to the tape by the tensioning device 11 this tension opposes the torque on the motor M causing the body of the motor M to twist. This twisting movement operates a tension responsive switch 82 associated with the body of the air motor M to actuate a pneumatic device 83 which, in turn, supplies air.,under pressure to the cylinders ET of the secondary tensioning device 12. The piston rods 61 are thus retracted moving the bracket 63 to the right from the position shown in FIG. 1. As soon as the bracket 63 moves away from the block 79 the gripper 75 is rotated in a clockwise direction by the torsion spring 76 and grips the tape securely against the bracket 63. Thereafter further movement of the bracket 63 to the right causes the tape to be drawn back from the loop past the gripper 19 to increase the tension applied to the tape.

-The pressure of air supplied to the cylinders ET is controlled to correspond to the, desired tension to be applied to the tape and as soon as the desired tension is attained, a signal is sent from a pressure drop valve 84 in the exhaust line from the cylinders ET, to the pneumatic cylinder G2 causing the gripper 19 to close and grip the tape against the nose plate 18. The cylinders ET then return to the normal forward position as illustrated in FIG. 1, allowing the tensioning gripper 75 to open soth'at the length of tape between the gripper 19 and the bracket 63 is released, while the tension in the loop is maintained by the gripper 19.

The pressure of air supplied to the cylinders ET is controlled to correspond to the desired tension to be applied to the tape. 11 this tension is not reached during the first stroke of the cylinders ET a limit valve 80 is engaged and operated by the bracket 63. The limit valve 80 operates a pneumatic circuit to supply air to the cylinder G2 which causes the gripper 19 to close and grip the tape against the nose plate to hold the tension in the loop. The air supply to the cylinders ET is then reversed and the piston rods 61 are extended. Simultaneously the motor M starts in reverse to prevent the loop being pushed between the bracket 63 and the block 79. This reversal does not release the tension in the loop, this being maintained by the gripper 19, but allows the tensioning gripper 75 to release the tape which is passed back through the bracket 63 as the piston rods 61 extend due to the motor M tending to run in reverse. The motor M resumes driving in the reverse direction until the piston rods 61 are fully extended whereupon the motor M stalls and the body of the motor M twists.

' The gripper 19 is then opened and the tensioning cycle is repeated any number of times until the tape tension reaches the required FlG., at which point the cylinders ET are stalled and prevented from completing a retraction stroke. At this stage the pressure drop valve in the exhaust line from the cylinders ET is actuated to cause air to be supplied to the cylinder G2 to close the gripper 19 as described above.

Simultaneously the pressure drop valve 84 reverses the air supply to the cylinder ET at the same time deenergizing the air motor M. The bracket 63 is thus advanced to the position shown in FIG. 1., and the length of the tape between the gripper 19 and the bracket 63 is released, while the tension in the loop is maintained by the gripper 19.

The pressure drop valve 84 also actuates operation of a friction-welding device which seals the overlapping ends of the loop together. This device comprises a vibrator mechanism 85 which produces a high frequency rubbing action between the ends of the loop to cause fusion at the contacting surfaces thereofThis action is continued at a pressure and for a duration sufficient to cause welding of the loop ends and then terminated.

Simultaneously with the vibrator 85 being brought into contact with the tape, cutter means (not shown) are operated to sever the sealed loop from the tape supply.

At the termination of'the sealing cycle, ejector means (not shown) are operated to free the sealed joint from thenose plate.

Although in the foregoing description the machinehas been described as used in conjunction with polypropylene tape it will be appreciated that the bindingmaterial employed may be of any suitable composition, for,. example nylon or another synthetic resin.

We claim: 1 l

1. In a package binding machine for-fuse with binding tape of synthetic resin materials comprising a base, means for feeding synthetic resin tape around a package supported on said base to. form a loop encircling the package with portions of said loop in overlapping relationship, means for retracting said loop onto the package and for applying a tension to said loop up to a required predetermined final value, and means for joining together said overlapping end portions of saidloop when said loop is subjected to said final value of tension, said loop retraction and tensioning means comprising a primary tensioning device for drawing said loop onto the package and for applying an initial tension thereto, and a secondary tensioning device for increasing the tension applied to said loop until said predetermined final value is attained, the improvement wherein said secondary tensioning device comprises a reciprocable assembly movable between a first advancedinoperative position and a second operative retracted position, means for sensing tension in said loop operative to actuate said reciprocable assembly between said first and second positions a sufficient number of times to bring said loopto said required final tension irrespective of any extension in the length of the binding tape due to the tension applied thereto, and gripper means for holding in said .loop the tension previv ously applied thereto, at least between-successive strokes of said reciprocable assembly. 4 2. A package binding machine as claimed in claim 1', incorporating means for determining when the initial tension applied to the loop attains a predetermined value and for actuating said secondary tensioning device when the said predetermined value of initial tension is attained.

3. A package binding machine as claimed in claim 2, .including separate operating means for actuating said secondary tensioning device, wherein said operating means are'actuated by said tension determining means.

4. A package binding machine as claimed wherein said primary tensioning device incorporatesv means for slack takeup in a length of said loop between said gripper means and said secondary tensioning device, said slack takeup means being operated simultaneously with movement of said reciprocable assembly during each return stroke between said second and first positions.

5. A package binding machine as claimed in claim 1,-

wherein the primary tensioning device comprises a plurality of rollers, an endless belt arranged to run on said rollers, guide means arranged to pass binding material in running engagement between said belt and a surface of one of said rollers,

means for tensioning said belt, and drive means for said belt, the arrangement being such that a tension applied to said belt acts to grip said tape between cooperating surfaces of said belt and the said one roller, and operation of said drive meanssaid first gripper to hold said tape against movement at least at I its free end and adapted to drive said motor in a reverse direction whereby said belt is driven in a reverse direction to retract said tape drawing said loop against the package until said predetermined initial tension is applied to said loop.

7. A package binding machine as claimed in claim 1, wherein said secondary tensioning device comprises at least in claim 1,-

one air cylinder having a piston rod movable between a first advanced position and a second retracted position, a bracket connected to said piston rod and movable therewith between said first and second positions on extension and retraction thereof, a tensioning gripper pivotally connected to said bracket, a spring adapted to urge said tensioning gripper towards said bracket in a direction to grip said tape against an adjacent surface of said bracket, means holding said tensioning gripper away from said tape when said piston rod is in said fully advanced position, said holding means comprising a sta tionary stop with which said tensioning gripper cooperates and relative to which said bracket is movableupon operation of said cylinder, whereby upon retraction of said piston rod said tensioning gripper is adapted to grip said tape against said bracket, and said bracket and said tape are withdrawn causing said loop to be drawn back to increase the tension applied to said tape.

8. A package binding machine as claimed in claim 7, wherein said tensioning gripper cooperates with said stop through an adjustable jack screw carried by said tensioning p 9. In a package binding machine for use with binding tape of synthetic resin materials comprising a base, means for feeding synthetic resin tape around a package supported on said base to form a loop encircling the package 'with portions of said loop in overlapping relationship, means for retracting said loop onto the package and for applying a tension to said loop up to a required predetermined final value, and means for joining together said overlapping end portions of said loop when said loop is subjected to said final value of tension, said loop retraction and tensioning means comprising a primary tensioning device for drawing said loop onto the package and for applying an initial tension thereto, and a secondary tensioning device' for increasing the tension applied to said loop until said predetermined final value is attained, the improvement wherein said secondary tensioning device comprises at least one air cylinder having a piston rod movable between a first advanced position and a second retracted position, a bracket connected to said piston rod and movable therewith between said first and second positions on extension and retraction thereof, a tensioning gripper pivotally connected to said bracket, a spring adapted to urge said tensioning gripper towards said bracket in a direction to grip said tape against an adjacent surface of said bracket, means for holding said tensioning gripper away from said tape against said spring when said piston rod is in said first advanced position, means for sensing tension in said loop operative to actuate said air cylinder and reciprocate said piston rod between said first and second positions a sufficient number of times to bring said loop to said required final tension irrespective of any extension in the length of the binding tape due to the tension applied thereto, and gripper means for holding tension in said loop at least between successive strokes of said piston rod.

10. A package binding machine as claimed in claim 9, wherein means are incorporated to regulate the pressure of air supplied to said air cylinder to correspond to said required final value of tension in said loop, a pressure drop valve actuated when said final value of tension is attained operating said gripper means to retain said final tension in said loop.

11. A package binding machine as claimed in claim 9, incorporating a limit valve for closing said gripper means when said piston rod is in said second retracted position and said tension in said loop is less than said required final value and for reversing a supply of air to said airy cylinder to move said piston rod into said first advanced position, whereafter the tensioning cycle is repeated until said required final value of tension is attained in said loop.

12. A package binding machine as claimed in claim 11, wherein said limit switch is actuated by the engagement with it of said bracket.

13. A package binding machine as claimed in claim 9, wherein said bracket comprises achannel section member havin a pair of spaced upstanding walls, a plurality of rollers rotata ly mounted between said walls, an endless belt arranged on said rollers, guide means defined between one of said rollers and said belt through which said tape is adapted to be passed in running engagement between said belt and the said one roller, and means for driving said belt in a direction to take up slack in said tape when said piston rod is moved between said second and said first positions.

Claims

1. In a package binding machine for use with binding tape of synthetic resin materials comprising a base, means for feeding synthetic resin tape around a package supported on said base to form a loop encircling the package with portions of said loop in overlapping relationship, means for retracting said loop onto the package and for applying a tension to said loop up to a required predetermined final value, and means for joining together said overlapping end portions of said loop when said loop is subjected to said final value of tension, said loop retraction and tensioning means comprising a primary tensioning device for drawing said loop onto the package and for applying an initial tension thereto, and a secondary tensioning device for increasing the tension applied to said loop until said predetermined final value is attained, the improvement wherein said secondary tensioning device comprises a reciprocable assembly movable between a first advanced inoperative position and a second operative retracted position, means for sensing tension in said loop operative to actuate said reciprocable assembly between said first and second positions a sufficient number of times to bring said loop to said required final tension irrespective of any extension in the length of the binding tape due to the tension applied thereto, and gripper means for holding in said loop the tension previously applied thereto, at least between successive strokes of said reciprocable assembly.

2. A package binding machine as claimed in claim 1, incorporating means for determining when the initial tension applied to the loop attains a predetermined value and for actuating said secondary tensioning device when the said predetermined value of initial tension is attained.

3. A package binding machine as claimed in claim 2, including separate operating mEans for actuating said secondary tensioning device, wherein said operating means are actuated by said tension determining means.

4. A package binding machine as claimed in claim 1, wherein said primary tensioning device incorporates means for slack takeup in a length of said loop between said gripper means and said secondary tensioning device, said slack takeup means being operated simultaneously with movement of said reciprocable assembly during each return stroke between said second and first positions.

5. A package binding machine as claimed in claim 1, wherein the primary tensioning device comprises a plurality of rollers, an endless belt arranged to run on said rollers, guide means arranged to pass binding material in running engagement between said belt and a surface of one of said rollers, means for tensioning said belt, and drive means for said belt, the arrangement being such that a tension applied to said belt acts to grip said tape between cooperating surfaces of said belt and the said one roller, and operation of said drive means causes lengthwise feeding movement of said tape.

6. A package binding machine as claimed in claim 5, wherein said drive means comprises a reversible motor, a coupling between said reversible motor and another of said rollers, means for drawing said motor in a forward direction to feed said tape around a package, a first gripper, and a switch actuated by feeding movement of the tape adapted to operate said first gripper to hold said tape against movement at least at its free end and adapted to drive said motor in a reverse direction whereby said belt is driven in a reverse direction to retract said tape drawing said loop against the package until said predetermined initial tension is applied to said loop.

7. A package binding machine as claimed in claim 1, wherein said secondary tensioning device comprises at least one air cylinder having a piston rod movable between a first advanced position and a second retracted position, a bracket connected to said piston rod and movable therewith between said first and second positions on extension and retraction thereof, a tensioning gripper pivotally connected to said bracket, a spring adapted to urge said tensioning gripper towards said bracket in a direction to grip said tape against an adjacent surface of said bracket, means holding said tensioning gripper away from said tape when said piston rod is in said fully advanced position, said holding means comprising a stationary stop with which said tensioning gripper cooperates and relative to which said bracket is movable upon operation of said cylinder, whereby upon retraction of said piston rod said tensioning gripper is adapted to grip said tape against said bracket, and said bracket and said tape are withdrawn causing said loop to be drawn back to increase the tension applied to said tape.

8. A package binding machine as claimed in claim 7, wherein said tensioning gripper cooperates with said stop through an adjustable jack screw carried by said tensioning gripper.

9. In a package binding machine for use with binding tape of synthetic resin materials comprising a base, means for feeding synthetic resin tape around a package supported on said base to form a loop encircling the package with portions of said loop in overlapping relationship, means for retracting said loop onto the package and for applying a tension to said loop up to a required predetermined final value, and means for joining together said overlapping end portions of said loop when said loop is subjected to said final value of tension, said loop retraction and tensioning means comprising a primary tensioning device for drawing said loop onto the package and for applying an initial tension thereto, and a secondary tensioning device for increasing the tension applied to said loop until said predetermined final value is attained, the improvement wherein said secondary tensioning device comprises at least one air cylinder having a piston rod movable between a first Advanced position and a second retracted position, a bracket connected to said piston rod and movable therewith between said first and second positions on extension and retraction thereof, a tensioning gripper pivotally connected to said bracket, a spring adapted to urge said tensioning gripper towards said bracket in a direction to grip said tape against an adjacent surface of said bracket, means for holding said tensioning gripper away from said tape against said spring when said piston rod is in said first advanced position, means for sensing tension in said loop operative to actuate said air cylinder and reciprocate said piston rod between said first and second positions a sufficient number of times to bring said loop to said required final tension irrespective of any extension in the length of the binding tape due to the tension applied thereto, and gripper means for holding tension in said loop at least between successive strokes of said piston rod.

13. A package binding machine as claimed in claim 9, wherein said bracket comprises a channel section member having a pair of spaced upstanding walls, a plurality of rollers rotatably mounted between said walls, an endless belt arranged on said rollers, guide means defined between one of said rollers and said belt through which said tape is adapted to be passed in running engagement between said belt and the said one roller, and means for driving said belt in a direction to take up slack in said tape when said piston rod is moved between said second and said first positions.