EP0838400A1

EP0838400A1 - Tension mechanism for strapping tool

Info

Publication number: EP0838400A1
Application number: EP97308365A
Authority: EP
Inventors: Nelson Cheung
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 1996-10-25
Filing date: 1997-10-21
Publication date: 1998-04-29
Also published as: JPH10129612A; TW379181B; MX9708148A; AU4098397A; KR19980033272A; CA2217063A1

Abstract

In a pneumatically operable strapping tool (10), a tension lever (24) is provided for controlling an internal pneumatic or air control valve which, in turn, controls an air motor drive operatively connected to a feedwheel (18) which tensions the strapping, disposed about an article or package to be strapped to a predetermined tension level. A seal lever (36) is provided in conjunction with the tension lever (24) so that upon completion of the tensioning phase of the strapping operation, the seal lever (36) is actuated to initiate the sealing phase of the strapping operation. To prevent a partial loss or a reduction of the tension level within the strapping which normally occurs during the transition between the tensioning and sealing phases of the strapping operation, the seal lever (36) is provided with a tang, tab, or ear member (40) which physically engages the tension lever (24) so as to maintain the tension lever at its operative or active position during the sealing phase of the strapping operation. In this manner, the tensioning phase of the strapping operation is not prematurely terminated and termination of the tensioning phase of the strapping operation is effectively delayed until the sealing phase of the strapping operation has been completed. Therefore, a proper tension level within the sealed strapping is achieved.

Description

The present invention relates generally to pneumatically operable tools for crimping or applying a metal seal about the overlapping portions of a tensioned loop of strapping which has been encircled about an object or article to be strapped for ensuring the integrity of the object or article during storage or transportation thereof, and more particularly, to a pneumatically operable strapping tool which is provided with a new and improved interlock mechanism defined between the tension and seal levers of the strapping tool so as to ensure the maintenance of a proper tension level within the strapping during the sealing operation.

Pneumatically operable tools, for crimping or applying metal seals about the overlapping portions of a tensioned loop of strapping which has been encircled about an object or article to be strapped, are of course well-known in the art. One early type of conventional pneumatically operable tool of the aforenoted type is disclosed within US-A3,552,450. Other more current types of conventional pneumatically operable strapping tools are disclosed within the SIGNODE Operation, Part and Safety Manual for the PNSC-12/58/34 Push Type Combination Strapping Tool, and within the ORGAPACX Operations Manual for the CR 25 A Steel Strapping Tool.

As can be readily appreciated from the ORGAPACX Operations Manual, and as more particularly noted and described on Pages 7 and 8 thereof, the tool comprises a green-colored tension lever and a yellow-coloured seal lever. As is known, each of these actuating levers operate or control internal valves which, in turn, operate or control pneumatically operable motors for operating or actuating the tension and sealing mechanisms. In utilizing the strapping tool in order to apply or secure tensioned strapping about an article or object to be strapped, the strapping is initially drawn from a supply reel of strapping material the free end of the strapping is inserted through the uncrimped seal member, and the loop of strapping is then encircled about the article or object to be strapped. After manually tightening the loop of strapping about the article or object so as to remove a large portion of slack within the looped strapping, an overlapped end of the strapping is inserted into the feedwheel mechanism of the strapping tool. The green-coloured tension lever is then actuated so as to actuate one of the internal valves which, in turn, actuates the air motor operatively associated with the feedwheel mechanism. The latter tensions the strapping, disposed about the article or object being strapped, to a predetermined tension level which will be indicated to the operator as a result of the feedwheel motor drive stalling. upon stalling of the feedwheel motor drive, the yellow seal lever is then actuated so as to similarly actuate the other one of the internal valves which, in turn, actuates the ir motor operatively associated with the sealing jaw mechanism so as to perform the seal crimping, sealing, and strap cutting operations.

While the aforenoted type of prior art strapping tools operate quite satisfactorily and have of course been quite successful in the marketplace, such tools do exhibit some operational drawbacks or deficiencies which, if properly addressed, would provide strapping which is more secure when such strapping is disposed about the objects, loads, articles or packages being strapped with such strapping. More particularly, the tension and seal levers of such pneumatically operated strapping tools are interrelated or mechanically interconnected with respect to each other by an internal cam mechanism. Consequently, when the seal lever is actuated after the tension or feedwheel motor drive stalls, the depression of the seal lever, through means of such interrelated or mechanically interconnected cam mechanism, permits the tension lever to be released from its actuated position. Accordingly, actuation of the tension or feedwheel motor drive, through means of the aforenoted internal pneumatic valving, is terminated. However, due to the fact that the strapping has necessarily been subjected to such a high degree of tension by the feedwheel motor drive in order to properly tension or load the strapping being disposed about the particular article, object, or package being strapped, due to the additional fact that the strapping exhibits a predetermined amount of inherent resiliency, and due to the passage of a predetermined amount of time, however small, which elapses between the termination of the tension or feedwheel motor drive and the actuation and completion of the sealing operation, the tension level or value achieved by the tension or feedwheel motor drive at the time of stalling is not able to be maintained and accordingly the amount of tension within the tensioned strapping is undesirably reduced to a level which renders the strapping, disposed about the article, load, or package, to exhibit a degree of fixation which is not as secure as is desired.

Therefore, there is a need in the art, to which the present invention is addressed, for a pneumatically operable strapping tool wherein the tension level, previously developed within the strapping during the tensioning phase of the strapping operation, is able to be fully maintained within the strapping, at the same tension level and without any reduction in such tension level, during the sealing phase of the strapping operation even though actuation of the seal lever has caused the internal cammed interlock mechanism defined between the seal and tension levers to disengage the tension lever from its actuated and locked position.

According to this invention a strapping tool for securing strapping about an article to be strapped, comprising:

a feedwheel for engaging a portion of strapping and applying tension forces to the strapping so as to tension strapping disposed about an article to be strapped during a tensioning phase of a strapping operation;

means for driving the feedwheel to cause the feedwheel to apply the tension forces to the strapping during the tensioning phase;

a tension lever movably mounted upon the tool for activating the means for driving the feedwheel; and,

a seal lever movably mounted upon the tool for activating a sealing mechanism for applying a seal member to the tensioned strapping during a sealing phase of said strapping operation;

is characterised by means interconnecting the seal lever and the tension lever to prevent the tension lever from deactivating the means for driving the feedwheel and/or to cause said tension lever to maintain the means for driving the feedwheel during said sealing phase of the strapping operation;

whereby driving of the feedwheel during the sealing phase is continued to continue the application of tension forces to the strapping during the sealing phase of the strapping operation.

In this manner, despite the internal release or disengagement of the tension lever from its downwardly actuated and locked position as a result of the engagement of an associated tension lever lock lever by means of an internal cam mechanism defined between the seal lever and the tension lever lock lever, the tension lever is physically maintained in its downward depressed position such that the internal pneumatic or air control valve, operatively associated therewith for controlling the air motor driving the strap tensioning feedwheel mechanism, is nevertheless maintained activated or open so as to conduct a supply of compressed air to the air motor driving the feedwheel mechanism. Therefore, the feedwheel mechanism is maintained active and in its driven state, and consequently, the predetermined tension level previously developed within the strapping by the feedwheel mechanism during the tensioning phase of the strapping operation is now able to be fully maintained within the strapping, at the same tension level and without any reduction in such tension level, during the sealing phase of the strapping operation.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing which is a partially exploded perspective view of the pneumatically operable strapping tool.

Referring now to the drawing, the pneumatically operable strapping tool, for fastening and securing strapping about articles, loads, packages, or the like in order to securely fasten or bind the same for storage or transportation purposes, is generally indicated by the reference character 10. The tool 10 conventionally comprises a feedwheel 12, which is provided for drivably engaging one of the overlapped ends of the strapping encircled about the article, load, package, or the like to be strapped, and the feedwheel 12 is adapted to be mounted upon a transversely extending feedwheel drive shaft 14 which projects laterally outwardly from a feedwheel gear housing 16. The feedwheel 12 is provided with an axial through-bore 18 which has a hexagonal configuration, and feedwheel drive shaft 14 is provided with a section 20 wherein the external configuration of section 20 is hexagonal such that the feedwheel drive shaft 14 is drivingly mated with feedwheel 12 as a result of the feedwheel drive shaft section 20 being accommodated within the hexagonally shaped through-bore 18 of the feedwheel 12. An air motor 22 has suitable drive components thereof, not shown, operatively connected to suitable gear components, not shown, of the gear housing 16 so as to transmit rotary drive from the air motor 22 to the feedwheel 12 through means of the gear housing 16 and feedwheel drive shaft 14.

The strapping tool 10 further comprises a tension lever 24 which is pivotably mounted upon an upstanding bracket 26 by means of a suitable pivot pin 28 such that the tension lever 24 is pivotably movable between a first, upper, inoperative or inactive position as illustrated, and a second, lower operative or active position, not illustrated, at which the tension lever 24 actuates a suitable air valve, not shown, which is fluidically connected to the air motor 22 so as to permit the drive thereof to be transmitted to the gear housing 16 and feedwheel 12. An upstanding tension lever lock lever 30 is pivotably mounted upon the tool 10 such that a first shoulder portion 32 thereof engages the tension lever 24 when the latter is disposed at its first, upper, inoperative or inactive position, and the tension lever lock lever 30 is also provided with a second shoulder portion, not shown, which is disposed vertically beneath the first shoulder portion 32 in a spaced arrangement with respect thereto and which is adapted to engage a notched or recessed portion 34 defined upon the tension lever 24 so as to retain the latter at its second, lower operative or active position. The tension lever 24 is normally spring-biased toward its first, upper, inoperative or inactive position, and tension lever lock lever 30 may be similarly spring-biased toward its normal upstanding position so as to properly engage the tension lever 24 when the latter is disposed at either one of its first, upper, inoperative/inactive or second, lower, operative/active positions.

As is also known in the art, the tool 10 further comprises a seal lever 36 which, in a manner similar to that of tension lever 24, is pivotably mounted upon an upstanding bracket 38 so as to be movable between a first, upper, inoperative or inactive position, as illustrated, and a second, lower, operative or active position, not illustrated, at which the seal lever 36 activates another suitable air valve, not shown, which controls the operation of another air motor, also not shown, for driving the sealing mechanism of the tool 10 so as to crimpingly secure the metal seal member onto the overlapped portions of the strapping. As has been noted hereinbefore, the sealing operation, as initiated by movement of the seal lever 36 from its first, upper, inoperative or inactive position to its second, lower, operative or active position, is implemented after a predetermined amount of tension has been impressed upon the strapping by means of the feedwheel 12 and as indicated to the operator by means of the stalling of the air motor 22 and feedwheel 12. In addition, it has also been noted that the seal lever 36 and the tension lever lock lever 30 are also conventionally mechanically interrelated or interconnected together by means of a suitable cam mechanism, not shown, whereby when the seal lever 36 is depressed downwardly so as to be moved from its illustrated first, upper, inoperative or inactive position to its illustrated second, lower, operative or active position, the tension lever lock lever 30 is cammed away from its position, at which it is engaged with the tension lever 24 so as to maintain the latter at its second, lower, operative or active position, to a position at which the tension lever 24 is released and permitted to return from its second, lower, operative or active position to its first, upper, inoperative or inactive position.

As a result of such movement of the tension lever 24, activation or operation of the air motor 22 for feedwheel 12 is terminated whereby tensioning of the strapping is stopped. Consequently, during the performance of the sealing operation by means of the tool's sealing mechanism as initiated or activated by means of the seal lever 36, and its associated air drive motor, not shown, and before completion of such sealing operation, and due to the fact that the strapping had necessarily been subjected to such a high degree of tension by the feedwheel 12 in order to properly tension or load the strapping being disposed about the particular article, load, package, or the like being strapped, due further to the additional fact that the strapping exhibits a predetermined amount of inherent resiliency, and due to the elapsed time which elapses between the termination of the feedwheel motor drive and the completion of the sealing operation, the tension level or value achieved by the feedwheel motor drive at the time of stalling of such feedwheel motor drive and initiation of the sealing operation is not able to be maintained and accordingly the amount of tension within the tensioned strapping encircled about the particular article, load, package, or the like being strapped is undesirably reduced to a level which results in the strapping exhibiting a degree of fixation which is not as secure as is desired.

In accordance then with the teachings of the present invention, the seal lever 36 is provided with an integral, laterally projecting or transversely extending tab, tang member, or ear 40 which has its distal free end portion thereof disposed above the tension lever 24. Consequently, when the seal lever 36 is depressed and moved pivotably downwardly during the initiation of a sealing operation, the arcuate movement of the tab or ear 40 will be such that such tab or ear 40 will encounter and engage an upper surface portion of the tension lever 24. Therefore, despite the fact that the aforenoted interconnecting or interlocking cam mechanism defined between the seal lever 36 and the tension lever locklever 30 normally results in the tension lever lock lever 30 being disengaged from its interlocked position or state with respect to the tension lever 24 so as to permit the tension lever 24 to be move away from its second, lower, operative or active position and toward its first, upper, inoperative or inactive position when the seal lever 36 is depressed downwardly so as to commence a sealing operation, such downward depression of the seal lever 30 now results in the integral tab or ear 40 thereof physically encountering and engaging the tension lever 24 such that the tension lever 24 cannot return to its normal or first, upper inoperative or inactive position. Therefore, the tension lever 24 effectively remains in its second, lower, operative or active position whereby the tension lever 24 still activates or opens its operatively associated air control valve, not shown, which permits compressed air to operate air motor 22 which, in turn, and by means of the suitable gearing housed within gear housing 16, drives the strap tensioning feedwheel 12.

As a result of such retention of the tension lever 24 at its second, lower, operative or active position and the continuance of the drive of feedwheel 12 during the initiation and performance of the sealing operation, the tension, originally developed within the strapping by means of the feedwheel 12 during the tensioning phase of the strapping operation, is now able to be fully maintained within the strapping, during the sealing phase of the strapping operation, at the same tension level impressed upon or developed within the strapping, during the tensioning phase of the strapping operation, when the air motor 22 driving the feedwheel 12 underwent stalling because the stall condition attendant the driving of the feedwheel 12 is effectively maintained. Therefore, the strapping does not experience any slackening or loss of tension and the strapping can therefore be secured, fastened, or bound about the particular article, load, package, or the like with the proper level of tension effectively preserved therein. Obviously, when the seal lever 36 is released so as to permit the same to return to its normal, first, upper, inoperative or inactive position upon the termination of the sealing operation, the tension lever 24 is likewise permitted to return to its normal, first, upper, inoperative or inactive position as a result of the disengagement of the seal lever tang or ear member 40 therefrom. Consequently, it is appreciated that the tensioning phase of the strapping operation is not prematurely terminated, termination of the tensioning phase of the strapping operation is effectively delayed until after the sealing operation has been completed, and that the tensioning and sealing operations are terminated substantially simultaneously.

It is to be further appreciated that the aforenoted release or disengagement of the tension lever 24 from its second, lower, operative or active position, as a result of the camming away of the tension lever lock lever 30 by the cam mechanism defined between the seal lever 36 and the tension lever lock lever 30, cannot be viably prevented by eliminating the cam mechanism defined between the seal lever 36 and the tension lever lock lever 30 because the cam mechanism serves an important operational role within the overall strapping operation. If such cam mechanism did not exist, then once the tension lever 24 was depressed and moved to its second, lower, operative or active position, and when the seal lever 36 was subsequently moved to its second, lower, operative or active position so as to initiate the sealing phase of the strapping operation, upon termination of the sealing phase of the strapping operation when the seal lever 36 is released from its second, lower, operative or active position so as to return to its first, upper, inoperative or inactive position, the tension lever 24 would nevertheless be disposed and retained at its second, lower, operative or active position which would then necessitate manual release or disengagement of the tension lever 24 from such operative or active position. In accordance with the present invention, such release or disengagement of the tension lever 24 occurs, in effect, automatically and simultaneously with the release or movement of the seal lever 36 from its second, lower, operative or active position to its first, upper, inoperative or inactive position because the tension lever 24 has been previously released or disengaged from the tension lever lock lever 30 as a result of the tension lever lock lever 30 having been moved away or released from its upright illustrated position by means of the aforenoted cam mechanism.

Thus, it may be seen that the present invention comprises an advancement in the strapping art to the effect that by means of the present invention, the deficiencies or drawbacks characteristic of the prior art or conventional strapping sealing systems are overcome and the problems resulting therefrom appropriately rectified. In particular, by means of the present invention, the tensioning phase of the strapping operation is not prematurely terminated and the termination of such tensioning phase of the strapping operation is, in effect, delayed such that the tension level, previously present within the strapping at the conclusion of the tensioning phase of the strapping as indicated to the operator by means of the stalling of the feedwheel drive motor, is not reduced. In particular, the tensioning phase of the trapping operation is positively and effectively continued until the sealing phase of the strapping operation has been completed. In this manner, the resultant tension developed within the strapping during the tensioning phase of the strapping operation is effectively preserved and is therefore substantially greater than the tension characteristic of conventional strapping secured about articles, loads, packages, or the like. In addition, such increased resultant tension level within the strapping facilitates severance of the strapping when the cutting implement of the strapping tool severs the sealed strapping from the supply of strapping material disposed upon a reel of strapping material upon conclusion of the sealing phase of the strapping operation.

Claims

A strapping tool (10) for securing strapping about an article to be strapped, comprising:

a feedwheel (12) for engaging a portion of strapping and applying tension forces to the strapping so as to tension strapping disposed about an article to be strapped during a tensioning phase of a strapping operation;

means for driving (22) the feedwheel to cause the feedwheel to apply the tension forces to the strapping during the tensioning phase;

a tension lever (24) movably mounted upon the tool for activating the means for driving (22) the feedwheel; and,

a seal lever (36) movably mounted upon the tool for activating a sealing mechanism for applying a seal member to the tensioned strapping during a sealing phase of said strapping operation;

characterised by means (40) interconnecting the seal lever (36) and the tension lever (24) to prevent the tension lever (24) from deactivating the means for driving (22) the feedwheel and/or to cause said tension lever (24) to maintain the means for driving the feedwheel (22) during said sealing phase of the strapping operation;

whereby driving of the feedwheel (18) during the sealing phase is continued to continue the application of tension forces to the strapping during the sealing phase of the strapping operation.
A strapping tool according to Claim 1, wherein: the means interconnecting the seal lever (36) and the tension lever (24) comprises an ear member (40) integral with the seal lever (36) for engaging the tension lever (24) when the seal lever is moved to a position at which it activates the sealing mechanism.
A strapping tool according Claim 2, wherein: the tension lever (24) is pivotably mounted upon the tool (10) between a first inoperative position at which the tension lever does not operate the means for driving (22) the feedwheel, and a second operative position at which the tension lever (24) activates the means for driving (22) the feedwheel;

the seal lever (36) is pivotably mounted upon the tool (10) between a first inoperative position at which the seal lever (36) does not operate the sealing mechanism, and a second operative position at which the seal lever (36) activates the sealing mechanism; and,

the ear member (40) projects laterally outwardly from the seal lever (36) to engage the tension lever (24) when the seal lever (36) is moved from the first inoperative position to the second operative position to maintain the tension lever (24) in or move it to its second operative position.
A strapping tool according to any one of the preceding Claims, wherein:
the strapping tool (10) is a pneumatically operable strapping tool.
A strapping tool according to Claim 4, wherein: the means for driving the feedwheel comprises an air motor (22).
A strapping tool according to any one of the preceding claims, further comprising:
a tension lever lock lever (30) for engaging the tension lever (24) and maintaining the tension lever (24) at its operative position, and being interconnected with the seal lever (36) such that when the seal lever (36) is moved into its operative position, the tension lever lock lever (30) is disengaged from the tension lever (24) to permit the tension lever (24) to be released from its operative position.