Bundle tie tensioning clutch

Provided is a tensioning clutch to be used in a tool for tensioning bundle, or cable, ties. A tensioning clutch according to the present invention includes a pawl mechanism having a removable pawl insert adapted to be reoriented or replaced without requiring significant disassembly of the housing of the tool. A tensioning clutch according to the present invention includes a pawl link, a tension abutment at least partly contemporaneously movable with the pawl link, and a pawl mechanism movably coupled to the pawl link. The pawl mechanism includes a pawl insert having one or more tie engagement surfaces, the insert being detachably coupled to a pawl body. The tie engagement surface of the insert may be biased towards, and movable away from, the tension abutment.

BACKGROUND OF THE INVENTION

The present invention relates generally to tools used in tensioning bundle ties and more specifically to a bundle tie tensioning clutch to be used in a bundle tie tensioning tool.

Flexible bundle ties are well known items. Such ties are used to secure wires, cables, tubing and similar items into tight, neat bundles. Typically, flexible bundle ties include a head portion and a tie tail portion extending from the head. In use, the tie tail is looped around the items to be secured and then inserted through the head. A locking or ratcheting mechanism in the head holds the tie tail in the head and secures the tie around the bundle. Preferably, the tie tail is pulled through the head under tension to draw the items to be secured into a tight bundle. Thereafter, the excess portion of the tie tail may be clipped off near the head.

Many flexible ties are economically molded of flexible plastic. For some applications, however, plastic has insufficient strength or other drawbacks, and metal ties are used. Metal ties include a flat strap portion and a locking head portion, each of which is made of a strong, durable metal such as stainless steel. As a rule, metal ties are significantly stronger than plastic ties of the same size and are typically pulled at much higher tensions than plastic ties when they are installed.

A variety of tools have been developed to enable workers to install flexible bundle ties with speed, uniformity and economy. Generally, such tools function to grip the tie tail portion of the tie after the tie has been looped around the items to be bundled. The tool pulls the tie tail until a predetermined desired tension is achieved, after which the tool cuts off the excess portion of the tie tail closely adjacent the head. Such tools greatly simplify the task of properly installing bundle ties.

In a typical tie tensioning tool, a tie is grasped and pulled by a tensioning clutch including a pawl, a pawl link, a shaft, a torsion spring, and tension abutment such as a backing plate. The tensioning clutch is generally slidably situated in a housing. The pawl link usually includes a yoke in which the pawl is rotatably supported on the shaft. The torsion spring includes a substantially stationary leg that cooperates with an aperture in the pawl link, and a biasing leg that cooperates with the pawl, thereby biasing the pawl toward the backing plate.

Various handheld tools have been developed to assist in the installation of flexible ties. In one well known form of such tool, the tool comprises a pistol or gun-like device having a movable trigger or lever that is squeezed by the operator to pull on the tie tail and thereby tension the tie. The operator continues squeezing the trigger until a predetermined tension is achieved after which a cutting blade adjacent the nose of the tool snaps upwardly to clip off the excess portion of the tie tail. A knob at the rear of the tool allows the worker to adjust or set the tension at which cutoff occurs. Examples of such manually operated handheld tools are shown in the inventors' U.S. Pat. No. 4,997,011, issued Mar. 5, 1991, U.S. Pat. No. 4,793,385 issued Dec. 27, 1998, and U.S. Pat. No. 5,921,290 issued Jul. 13, 1999, commonly owned by the assignee hereof.

The pawls of prior devices were normally cast in hardened steel and had teeth, which gripped a tie when the tie was inserted between the pawl and the cooperating tension abutment or backing plate. The pawl is a wear part of a tensioning tool. That is, eventually and frequently, the teeth on the pawl wear down and the clutch needs to be repaired or the pawl replaced. This is especially true when the tensioning tool is used with metal ties, such as stainless steel ties. Replacing or repairing a damaged or worn pawl is both time and labor intensive. Most prior devices require that the tool be taken out of service for repair, and replacement of the pawl requires disassembly of the tool's housing. As with any industrial teardown repair, care must be taken to ensure that reassembly is properly executed, and the tool must be tested prior to reinstatement of service.

Therefore, the art of tensioning bundle ties may benefit from a bundle tie tensioning clutch having an engagement surface that may be changed when desired, without significant disassembly of the remainder of the tensioning tool.

SUMMARY OF THE INVENTION

The present invention provides a bundle tie tensioning clutch having an engagement surface that may be changed when desired, without significant disassembly of the remainder of the tensioning tool.

In one embodiment, a tensioning clutch according to the present invention includes a pawl link, a tension abutment at least partly contemporaneously movable with said pawl link, and a pawl mechanism movably coupled to the pawl link. The pawl mechanism includes a pawl insert that is detachably coupled to a pawl body. The pawl insert includes a tie engagement surface, which is preferably biased towards and movable away from, the tension abutment, which may be a backing plate coupled to the pawl link. While the backing plate and pawl link could be provided separately, the backing plate may, instead, be formed integrally with the pawl link. The pawl mechanism is rotatably supported by the pawl link. The pawl link may form a yoke at least partially in which the pawl mechanism is movably supported. Such movable support may be provided in the form of rotatable support upon a bearing shaft.

The pawl insert is detachably coupled to said pawl body, which may be, for example, by a threaded mounting bolt inserted through said pawl insert and engaging a threaded mounting aperture located in the pawl body. In another embodiment, the pawl insert may be a polygonal insert having a plurality of tie engagement surfaces, such as three tie engagement surfaces. The pawl insert may be formed from, or at least include, a material including a carbide. The insert may include a tool surface, an access surface generally opposed from the tool surface by an insert thickness, at least one side surface extending from the access surface to the tool surface, and a mounting aperture accessible through the insert thickness. The insert tie engagement surface is preferably formed by the junction of the side surface and the access surface. The pawl body preferably includes an insert lip adapted to interface to at least one side surface of the pawl insert. The insert access surface may be a polygonal, planar surface, such as a triangular surface, for example. Similarly, the insert tool surface may be a polygonal, planar surface, such as a triangular surface.

The pawl mechanism of a tensioning clutch according to the invention may be biased towards the tension abutment by a torsion spring exerting a first force against said pawl link and a second force against the pawl mechanism. The second force may be exerted against the pawl body.

In another embodiment, an improvement is provided for a bundle tie tensioning tool having a mechanism for grasping a bundle tie. The improvement includes a pawl mechanism movably coupled to a pawl link. The pawl mechanism includes a pawl insert detachably coupled to a pawl body. Furthermore, the pawl link may be adapted for substantially linear reciprocal sliding movement within a housing of the tool.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the Figures,FIG. 1andFIG. 2show a prior bundle tie tensioning tool10. The handheld tool10may be optimized for use with metal, and, in particular, stainless steel, ties. The handheld tool10includes a generally gun or pistol shaped housing14having a handle or grip portion20, a barrel portion22and a trigger24. The housing14is usually provided in a plurality of parts held together by threaded fasteners15. The trigger24is located forwardly of the grip20and under the barrel portion22where it falls naturally under the fingers of the operator. The trigger24is movable from an initial position spaced away from the grip20to a second position nearer the grip20.

A tie12is tensioned by means of a tensioning clutch26, which is slidably disposed at least partially within the barrel portion22of the housing14. The tensioning clutch26grips a tail portion18of the tie12and pulls it rearwardly as the trigger24is moved from the initial position to the second position. When the trigger24is released, it springs forwardly to the initial position. At the same time, the tensioning clutch26releases the tie tail18and moves forwardly relative to the tie tail18. As the trigger24is once again squeezed, the tensioning clutch26once again grips the tie tail18and draws it rearwardly. The process is repeated until a desirable tension is achieved in the tie12.

With reference more particularly toFIG. 2, the construction of the prior tensioning clutch26may be more fully explained. As illustrated, the tensioning clutch26is internally mounted at least partially in the barrel portion22and includes a pawl link40mounted for horizontal, linear reciprocating movement relative to the housing14. The pawl link40may be supported for linear sliding movement within the housing14by means of slider blocks41received within rectangular-sectioned channels43formed on the interior wall of the housing14. When a tie12is inserted into the tool10, the tie tail18is gripped by means of a tie gripping pawl42carried upon a shaft45disposed towards the forward end of the pawl link40. The gripping pawl42is pivotally attached to the pawl link40and is upwardly biased toward a tension abutment such as a backing plate44, which is also carried by the pawl link40. In the prior device10, the backing plate44is integrally formed with the pawl link40. The gripping pawl42is rotatably biased toward the backing plate44by means of a torsion spring46so that a bundle tie tail18inserted therebetween will be engaged by and between the pawl42and the backing plate44. The upper surface of the pawl42is provided with teeth or serrations42athat engage the tie tail18.

A nose guide block38may be provided within the housing14. The guide block38includes a surface that engages the gripping pawl42when the pawl link40is at the leftmost or initial position. Such engagement pivots the gripping pawl42away from the backing plate44to facilitate insertion of the tie tail18into the tool10. When the pawl link40moves toward the right, the tie tail18is pinched between the gripping pawl42and the backing plate44. The tie tail18is thus pulled along with the pawl link40. It will be appreciated that, as the pawl links40move to the right, the gripping pawl42grips the tie tail18to pull the tie tail18and thereby tension the tie12. When the pawl link40is reciprocated to the left, the gripping pawl42loosens its grip on the tie tail18, thereby permitting the pawl link40to return to its initial position without simultaneously moving the tie tail18.

Turning now toFIG. 3andFIG. 4, an embodiment100of a bundle tie tensioning clutch according to the present invention is shown. Like prior devices, the tensioning clutch100includes a pawl link140, a pawl mechanism142, a tension abutment such as a backing plate144, a shaft145, and a torsion spring146. The clutch100also preferably includes a tool interface141that may include mounting structure such as a threaded stud to be linked to the drive mechanism of the tool and bearing supports to provide a mounting location for slide blocks, similar to those41inFIG. 2. A tensioning clutch according to the present invention may be used with a variety of tensioning tools that may be actuated by, for example, mechanical means, pneumatic means, electromechanical means, electrical means, manual means, or any combination thereof. Further, the clutch100may include a transition plate148mounted to the pawl link140by a pair of threaded fasteners149. As explained further below, the pawl mechanism142of a tensioning clutch100according to the present invention includes a replaceable pawl insert152. The pawl insert152is mounted to the pawl body150in a manner that allows removal and replacement of the insert152without the need for disassembly of the entire tensioning tool.

FIG. 5provides an assembly view of an embodiment of a pawl mechanism142according to the present invention. The pawl mechanism142includes a pawl body150and a replaceable pawl insert152, which is coupled to the pawl body150preferably by a threaded mounting bolt154. If a threaded mounting bolt154is used, the mounting bolt154may be removed by using a tool, such as a manual screwdriver200, for example. Such removal may occur preferably while the clutch100is operatively mounted in a tensioning tool. The pawl body150preferably includes structure to maintain the pawl insert152in a desired orientation. In this example, the pawl body150has an insert lip151, against which a side of the pawl insert152rests when coupled to the body150, and a threaded mounting aperture153, adapted to accept the threaded mounting bolt154. The pawl body150is preferably formed from any desirable supportive material, such as steel, aluminum, etc. The pawl insert152is preferably a commercially available triangular carbide insert such as a G10E insert available from Sumitomo Electric Carbide, Inc. of Mount Prospect, Ill. The insert152has preferably a plurality of tie engagement surfaces155. While a triangular insert152is preferred, any polygonal insert152, such as a rectangle, a pentagon, a hexagon, etc., may also be used. Use of a polygonal insert152having multiple engagement surfaces155provides a user the ability to quickly adjust the insert152, thereby providing a sharp edge when one is desired. Inserts152having different shapes than those listed may also be employed.

FIG. 6shows the embodiment100ofFIG. 3that has been incorporated into the barrel portion122of a bundle tie tensioning tool110similar to the prior tool10ofFIG. 1. In this position, the pawl mechanism142is rotated rearwardly by the nose guide block138, thus parting the pawl insert152from the backing plate144to ease lateral tie insertion.

FIG. 7also shows the embodiment100ofFIG. 3that has been incorporated into the barrel portion122of a bundle tie tensioning tool110similar to the prior tool10ofFIG. 1; however, the tensioning function of the tool has been activated, e.g. by way of a user grasping a trigger on the tool110, so that the clutch100has been retracted away from the nose guide block138thereby allowing the torsion spring146to bias a tie engagement surface155of the pawl mechanism142against the tie12. The tie12is thus gripped between the pawl insert152and the backing plate144during a majority of the retraction of the clutch100.