US3035814A - Apparatus for tensioning flexible binding material around packages and the like - Google Patents

Description

May 22, 1 F. w. MOSEY ETAL 3,

APPARATUS FOR TENSIONING FLEXIBLE BINDING MATERIAL AROUND PACKAGES AND THE LIKE Filed April 29, 1959v 5 Sheets-Sheet 1 gn fl 3 Q Q Q:

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APPARATUS FOR TENSIONING FLEXIBLE BINDING MATERIAL AROUND PACKAGES AND THE LIKE Filed April 29, 1959 5 Sheets-Sheet 2 PwZ 1 M4 w y 1962 F. W. MOSEY ETAL 3,035,814

APPARATUS FOR TENSIONING FLEXIBLE BINDING MATERIAL AROUND PACKAGES AND THE LIKE Filed April 29, 1959 5 Sheets-Sheet 3 V WW5:

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May 22, 1962 F. w. M

OSEY ETAL APPARATUS FOR SIONING F E IBLE BINDING ARO THE LI MATERIAL PACKAGES D Filed April 29, 1959 5 Sheets-Sheet 5 United States Patent APPARATUS FOR TENSIONING FLEXIBLE BIND- ING MATERIAL AROUND PACKAGES AND THE LIKE Frederick William Mosey, Oswald Victor Langford, and Jack Wild, London, England, assignors to Seal-Less Strapping Limited, London, England, a corporation of Great Britain Filed Apr. 29, 1959, Ser. No. 809,761 Claims priority, application Great Britain May 9, 1958 7 Claims. (Cl. 254-51) This invention relates to a mechanism for tensioning flexible material after the material has been looped for example around a package and before the overlapping portions of the material are interconnected. This mechanism is of the type essentially comprising two grippers. The first gripper is reciprocally movable towards and away from the second gripper for successively applying a tension to the material; the second gripper being adapted to hold the tension after it has thus been applied by the first gripper. The first gripper is adapted to open during its return stroke to take a fresh hold on the material and the second gripper is adapted to open to permit passage of the material through it during the tensioning strokes of the first gripper. In mechanisms of this type a free end of the material may be held by means of an anchoring gripper or otherwise, as for example by being hooked to a seal. Moreover, the tensioning strokes of the first gripper may be used either to pull or to push the material through the second gripper and similarly either to pull or to push the material through an associated jointing or sealing device with both the grippers disposed either on the far or on the near side of the latter, or with one of the grippers on one side and one on the other.

The required reciprocation of the first gripper may be effected by the swinging of a pivoted lever on which said gripper is mounted, a tensioning means of this character to which the present invention can be advantageously applied being one in which both grippers are on the far side of a jointing device with the first gripper arranged outwardly of the second gripper so that it is adapted to tension the material by pulling it through both the second gripper and said device.

In accordance with the present invention the reciprocation of the first gripper is eflected by successive power thrusts imparted thereto. These thrusts are preferably delivered all in one direction only, against the reaction of a spring or the like, so that the consequent positive strokes of said gripper in this direction leave it free for intermediate or return strokes in the opposite direction under the influence of said spring. The gripper is preferably thrust positively in the direction for tensioning with a force which is limited according to the magnitude of final tension desired in the material. The power may be conveniently applied to the aforementioned lever which carries said gripper.

Successive thrusts on the gripper of an appropriate kind can be produced by means of a cam of star form, preferably rotatable by a motor which is self-stopping in face of the resistance opposed by the full tension required. A pneumatic motor which is capable of remaining in operation until this predetermined upper power limit is reached simply by being kept in communication with a source of compressed air, is especially suitable for the purpose. Moreover the maximum power thus applied can be readily controlled by means of a pressure regulator in the air supply to the motor. A single-acting motor of this kind is adapted to rotate said cam unidirectionally, without requiring any reversal of the cam as a consequence of or following release of the air pressure acting on said motor on conclusion of one tensioning operation and before starting another. Such unidirectional rotation of the cam also enables its sectors to be contoured unsymmetrically, so that each sector gives rise to a quick return of the gripper followed by a relatively gradual tensioning stroke thereof.

The accompanying drawings show by way of example a tool for banding packages or the like with metal strip in which the latter is tensioned in accordance with the invention.

In these drawings:

FIGURE 1 is a front elevational view of a mechanism constructed in accordance with this invention;

FIG. 2 is a corresponding view partly in section, with the front cover plate and pneumatic motor power device removed;

FIG. 3 is a rear elevational View again omitting the pneumatic motor, but indicating the limits of movement of the levers for operating the anchoring gripper and the joining mechanism;

FIG. 4 is an end elevation from the left of FIGURE 1;

FIGURE 5 is a sectional view taken substantially along the line 55 of FIG. 1;

FIG. 6 is a detail front elevational view to show the loading positions of the tensioning and holding grippers; and

FIG. 7 is a similar detail view to show the normal range of movement of the tensioning gripper under the influence of the pneumatic motor.

In the tool thus illustrated, the joint formation between the overlapping lengths or portions S and S of the previously looped strip material is effected in a manner in accordance with the teachings of United States Patent No. 2,549,626. For this purpose the tool comprises a base plate 1 with a gripper 2 for anchoring an end of underlying strip portion S Strip portions S and S extend in overlapping manner over the lower jointing dies 3 bedded in said plate. Overlapping strip portion S thence extends to the left in FIG. 2 above the anvil 4 to the tensioning means, to be hereinafter described, and then preferably beyond that to a supply coil.

The joining of the overlapping strip portions is efiected by the coaction of upper dies 5 and 6 with the dies 3. The upper dies are successively moved toward lower dies 3 into contact with the overlapping lengths of strip. Die 5 is moved sufliciently at least to hold these lengths before the upper strip part S is severed by the blade 7 on die 6 against the anvil during the subsequent movement of die 6 into engagement with said lengths intermediate the severed end of strip portion S and die 5.

Such lowering of the dies, in sequence, is effective by the pair of lever handles 8 and 9 which are adapted to be simultaneously swung oppositely on their respective journals 8a and 9 from the position shown in solid lines to the joining or operative position shown in broken lines in FIG. 3. Handles 8 and 9 are intercoupled by gearing between their hubs 8b and 9b at the rear of the tool as shown in FIG. 3 and their operative or joining stroke is adjustably limited by abutment of the stop 8c on the hub 8b against the hub 9b. The dies 5 and 6 are actuated respectively by the consequent rotation of the journals 8a, 9a through the eccentrics 5a, 6a thereon and the pivotal links 512, 6b as illustrated in FIG. 2. Die 5 is also used to control a catch 10 for preventing lateral displacement of the strip part S until the overlapping strip parts are gripped by that die. Catch 10 has a portion extending into a slot of die 5 whereby the catch is freely lowered into operative position when die 5 is raised (see FIG. 2) and the catch lifted clear of said strip part during the final stage of the descent of die 5. Anchoring gripper 2 is controlled by and can be freely closed onto strip part S by its lever handle 2a when dies 5 and 6' are raised. However, this gripper is thrown open by the engagement of its operating handle by jointing lever 9 during the final part of the operative stroke of the latter (see FIG. 3).

Turning now to the means for tensioning the strip part S with which the present invention is more immediately concerned, this consists of the combination of a tensioning gripper, generally denoted 11, and a holding gripper, generally denoted 12. Tensioning gripper 11 is pivotally mounted on pin 11a which is spaced outwardly in the tensioning direction (to the left in FIG. 2) from movable dies 5 and 6. Holding gripper 12 is pivota ly mounted on pin 12a which is disposed intermediate pivot pin Ma and the movable dies.

Gripper 11 consists of a lever 11b pivotally mounted on pin 110, a lower jaw part 11c integral with lever 11b and an associated upper jaw member 11d which is movable relative to lever 11b and lower jaw 110 about pivot pin 11a. Upper jaw member lid is urged toward its closed position for engagement with the strip material by a compression spring 11e acting between said ja-W member and lever 11b. As will be described, gripper 11 may be opened manually when required by the extension piece 11 Gripper 12 consists of an upper movable jaw member 1212 on the pivot 12a associated with anvil 4 which in this case is fixed and acts as a lower jaw. Movable jaw member 12b is urged by compression spring 120 towards the closed position for engagement with the strip material. As may be seen spring 120 acts between jaw member 12b and an adjacent part of the tool body. The two upper jaw members 11d and 12b are thus so constructed that the operative parts of both members beneath the respective pivot 11a and 1242 open in the direction of tensioning, i.e. to the left in FIGS. 1, 2, 6 and 7.

The lever 11b of the tensioning gripper is adapted to be swung so that the lower jaw 11c thereon moves outwardly (to the left) during tensioning (see FIGS. 6 and '7), with the associated upper jaw 11d closed onto the strip to hold it. As lever 11b returns inwardly (to the right) the lifting of upper jaw lid in the same direction is eifected against spring He by the engaged strip then held stationary by gripper 12. The limits of this lever movement are shown in FIG. 7. The corresponding actuation of gripper 12 is similarly automatic, its upper jaw member 1212 being lifted by the strip as it is drawn through by the successive tensioning strokes of gripper 11 and closed by spring 120 during the return strokes of that gripper, so that each gripper is opened by the strip in turn whilst the other is closed by its compression spring.

On conclusion of jointing, both grippers may however be opened simultaneously for strip removal and loading, by positively throwing over all their movable parts together in the same direction as in tensioning, by means of the handle extension 11 Manual pressure on this handle being applied above pivot 11:: first directly causes lifting of the jaw member 11d followed, when spring He has been fully compressed, by inward swinging of lever 11b beyond the normal limit of its tensioning stroke so that the upper part of said lever abuts against stop 1201 on the jaw member 1% of the holding gripper above the pivot 12a. This abutment with stop 12d causes jaw member 12b to pivot in a clockwise direction toward its open position against the resistance of compression spring 120, as shown in FIG. 6.

The powering of lever 11b in accordance with the present invention is effected by means of a multi-throw star cam 13 which is adapted to engage roller follower 13a disposed on the upper extremity of lever 11b above pivot 11a. Rotation of this cam in a counterclockwise direction produces a succession of swings of lever 11b of sufiicient amplitude to produce the normal tensioning and return strokes of gripper 11 as previously described. Follower 13a is held in engagement with the cam by means of a'tension spring 13b pulling on the upper part of lever 11b. The follower and upper end of lever 11b are thus moved inwardly (to the left) against the resistance of spring 1312 resulting in movement of gripping jaws 11c and 11a. to the left in the tensioning direction.

The thrust of the cam is therefore delivered to the gripper outwardly to produce the tensioning strokes thereof, whilst the return strokes are caused by the spring. This arrangement also has the advantage that it does not interfere with the final simultaneous opening of the grippers in the manner already described, for lever 1117 may be easily pivoted to lift the follower from the cam against the resistance of spring 13b. Because of its high speed of rotation, the cam 13 is preferably shielded by a safety guard 17.

The cam is here rotatable unidirectionally anticlockwise (as seen in FIGS. 2 and 7) so that its three sectors can be similarly contoured unsymmetrically to give a quick return stroke of gripper 11 under the influence of spring 13b when the follower drops behind one of the sharp corners 130 of the cam, tending to snap the gripper open, and a relatively gradual tensioning stroke as the follower rides up the slope 13d to the next corner.

As shown in FIG. 5 cam 13 has a stub shaft 13s by which it is mounted in the back plate 14 of the tool in a bearing 1%, and is rotated unidirectionally in the required manner by a pneumatic motor 15 which may be of the fin turbine type commonly known as a nutsetter. This motor extends longitudinally above the body of the tool supported by suitable strap parts 15a and 15b from the tool front plate 16 (see FIG. 1), with its transmission head 15c adjacent the cam and its output spindle 15d squared and rearwardly directed from said head for engagement in a corresponding socket 13f of the cam, as shown in FIG. 5.

The speed contemplated for the motor 15 is up to approximately 15,000 revolutions per minute in the turbine. With appropriate gearing a suitable output rate for the cam of between about to about 350 rotations per minute may be obtained. The maximum power which the motor can exert and thus the maximum tension which can be applied by the machine to the strip material is dependent upon the pressure of its air supply. This power can, however, be adjustably controlled below its upper limit to apply a lesser tension by means of a simple regulator 15e (see FIG. 1), whereby the cross section of the supply line is restricted. This has the effect of diminishing the air flow and of thereby reducing the rotation rate of the motor and consequently delaying the build-up of its torque over the short period during which the motor is required to remain in operation for tensioning, so that when stalling of the motor begins to take place and the predetermined tension has been applied to the material the operation can be terminated. In this connection it Wlll be understood that the actual duration of the operation of the motor is controlled by its lever 15 which serves to open and close the air supply thereto fully.

We claim:

1. An apparatus for tensioning flexible strip material which has been previously looped about a package or the l ke to provide two adjacent portions of said strip material comprising the'ends of said loop, said apparatus comprising means for engaging and holding one of said portions of the strip material, a lever reciprocably movable with respect to said holding means, a gripping element mounted on said lever effective to grip the second portion of said strip material to apply a tension to said looped material between said first and second portions thereof when said lever is moving in one direction and effective to release said material when said lever is moving in the opposite direction, gripping means for gripping said second portion of said material during movement of said lever in said opposite direction, spring means urging said lever in said opposite direction, a rotatable star-shaped cam engaging a portion of said lever, and power means for rotating said cam to cause periodic movement of said lever in said one direction against the resistance of said spring means.

2. The structure of claim 1 wherein said power means is self-stopping upon the application of a predetermined amount of tension to said strip material by said lever and said gripping element.

3. The structure of claim 2 wherein said power means is a pneumatic motor operable to apply a predetermined force to said cam, whereby a predetermined tension may be applied to said strip material.

4. The structure of claim 2 wherein said power means includes a source of compressed air and a pneumatic motor in communication with said compressed air source to apply a force of predetermined magnitude to said cam, whereby a predetermined tension may be applied to said material.

5. The structure of claim 2 wherein said power means includes a source of compressed air, a pneumatic motor in communication with said compressed air source for applying a rotative force to said cam, and pressure-regulating means intermediate said compressed air source and said motor for regulating the air supply to the motor, whereby the amount of force applied to said cam and the amount of tension applied to said strip material may be regulated.

6. The mechanism constructed in accordance with claim 5 wherein said motor delivers a unidirectional force to said cam to effect rotation of said cam in one direction only.

7. The structure of claim 6 wherein the radially protruding sectors of said star-shaped cam are of unsymmetrical contour for efiecting a gradual tensioning stroke followed by a quick return of the lever and gripping element.

8. An apparatus for tensioning flexible strip material which has been previously looped about a package or the like to provide two adjacent portions of said strip material comprising the ends of said loop, said apparatus comprising means for engaging and holding one of said portions of the strip material, a lever pivotally and reciprocably movable with respect to said holding means about a fixed axis and having a first jaw portion, a gripping element mounted for pivotal movement with re- Spect to said lever and said holding means about the pivotal axis of said lever, said gripping element having a second jaw portion effective to cooperate with the first jaw portion carried by said lever to grip the second portion of said material and to apply a tension to said looped material between said first and second portions thereof when said lever is moving in one direction and efiective to release said material when said lever is moving in the opposite direction, gripping means adjacent said lever for gripping said second portion of said material during movement of said lever in said opposite direction, manually operative means for effecting release of the second portion of the strip material by said lever and for effecting movement of said lever in said one direction into engagement with said gripping means to release the second portion of the strip material therefrom, means urging said lever in said opposite direction and power actuated means operatively engaging said lever to repetitively move said lever in said one direction short of engagement with said gripping means for applying tension to said material.

9. An apparatus for tensioning flexible strip material which has been previously looped about a package or the like to provide two adjacent portions of said strip material comprising the ends of said loop, said apparatus comprising means for engaging and holding one of sa1d portions of the strip material, a lever pivotally and reciprocably movable with respect to said holding means about a fixed axis and carrying a first jaw portion adjacent one end thereof, a gripping element mounted for pivotal movement with respect to said lever and to said holding means about the pivotal axis of said lever and carrying a second jaw portion cooperating with said first jaw portion carried on said lever to grip the second portion of said strip material to apply a tension to said looped material between said first and second portions thereof when said lever is moving in one direction and efiective to release said material when said lever is moving in the opposite direction, gripping means pivotally mounted adjacent said lever for gripping the second portion of the material during movement of said lever in said opposite direction, said gripping element having a handle portion and a lever engaging portion, said gripping element may be moved in said one direction to release the second portion of the strip material from between first and second jaw portions and said lever may be moved in said one direction into engagement with said gripping means to pivot said gripping means, whereby the second portion of material may be released by said gripping means, means urging said lever in said opposite direction, and power actuated means operatively engaging said lever to move said lever in said one direction short of engagement with said gripping means for applying tension to said material.

10. The structure of claim 9 in which said power actuated means is efi'ective to apply successive power strokes to said gripping means to effect the application of tension to said material in increments, and adjustable means is provided for adjustably regulating the force applied to said lever by said power actuated means, whereby the amount of tensioning in the strip material may be regulated.

11. An apparatus for tensioning flexible strip material which has been previously looped about a package or the like to provide two adjacent portions of said strip material comprising the ends of said loop, said apparatus comprising means for engaging and holding one of said portions of the strip material, a gripping element mounted for reciprocable movement with respect to said holding means and effective to grip the second portion of said strip material to apply a tension to said looped material between said first and second portions thereof when moving in one direction and eifective to release said material when moving in the opposite direction, gripping means for gripping said second portion of said material during movement of said gripping element in said opposite direction, means urging said gripping element in said opposite direction, a rotatable star-shaped cam engaging a portion of said gripping element, and power means for rotating said cam to cause periodic movement of said gripping element in said one direction.

12. The structure of claim 11 wherein said power means includes a source of compressed air, a pneumatic motor in communication with said compressed air source for applying a unidirectional rotative force to said cam, and pressure-regulating means intermediate said compressed air source and said motor for regulating the air supply to the motor, whereby the amount of force applied to said cam and the amount of tension applied to said strip material may be regulated.

13. The structure of claim 11 wherein the radially protruding sectors of said star-shaped cam are of unsymmetrical contour for effecting a gradual tensioning stroke followed by a quick return of the gripping element.

14. An apparatus for tensioning flexible strip material which has been previously looped about a package or the like to provide two adjacent portions of said strip material comprising the ends of said loop, said apparatus comprising means for engaging and holding one of said portions of the strip material, first gripping means reciprocably movable with respect to said holding means, said first gripping means when moving in one direction being eifective to grip the second portion of said strip material -to apply a tension to said looped material between said first and second portions, and when moving in the opposite direction being effective to release said material, second gripping means for gripping said second portion of said strip material during movement of said first gripping means in the opposite direction, motor drive means which when energized has a continuous power output, and means intermediate said motor drive means and said first gripping means for applying the power from said motor drive means to said first gripping means in successive and discrete thrusts, whereby said first gripping means may be reciprocated until the desired tension is produced in the looped strip material.

15. The structure of claim 14 including means for adjustably regulating the continuous power output of said motor drive means.

16. An apparatus for tensioning flexible strip material which has been previously looped about a package or the like to provide two adjacent portions of said strip material comprising the ends of said loop, said apparatus comprising means for engaging and holding one of said portions of the strip material, first gripping means reciprocably movable with respect to said holding means, said first gripping means when moving in one direction being efiectve to grip the second portion of said strip material to apply a tension to said looped material between said first and second portions, and when moving in the opposite direction being effective to release said material, second gripping, means for gripping said second porton of said strip material during movement of said first gripping means in the opposite direction, return means urging movement of said first gripping, means in said opposite direction of reciprocation, motor drive means which when energized has a continuous power output, and means intermediate said motor drive means and said first gripping means for applying the power from said motor drive means to said first gripping means in successive and discrete thrusts, whereby said first gripping means will be repetitively first driven in said one direction by said motor driven means and then returned in the opposite direction by said return means.

'17. An apparatus for tensioning flexible strip material which has been previously looped about a package or the like to provide two adjacent portions of said strip material comprising the ends of said loop, said apparatus comprising means for engaging and holding one of said portions of the strip material, a lever reciprocably movable with respect to said holding means, a gripping element mounted on said lever eitective to grip the second portion of said strip material to apply a tension to said looped material between said first and second portions thereof when said lever is moving in one direction and effective to release said material when said lever is moving in the opposite direction, gripping means for gripping said second portion of said material during movement of saidlever in said opposite-direction, spring means urging said lever in said opposite direction, motor drive means having a continuous power output when energized, and means intermediate said motor drive means and said lever for applying the power from said motor drive means to said lever in successive and discrete thrusts, whereby said lever and the gripping element thereon will be repetitively first driven in said one direction by said motor driven means and then returned in the opposite direction by said spring means.

References Cited in the file of this patent UNITED STATES PATENTS 1,988,730 Harvey Jan. 22, 1935 2,229,786 Abbott Jan. 28, 1941 2,375,769 Childress et a1 May 15, 1945 2,881,636 Palrnleaf Apr. 14, 1959

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