Strap Tensioning And Cut-off Tool

Abstract

A pistol-grip, hand-operated tensioning and cut-off tool for cable straps or bundle ties is disclosed. The tool receives the free end of the strap with the buckle or strap head held against the tool barrel. The strap is tensioned to a level which may be adjusted. When this level is reached, the tool automatically cuts off adjacent to the strap head. During the tensioning, the trigger responds to manual pressure to pivot about a pintle and slide a draw bar in a strap tightening direction. When the tension of the strap exceeds the tension of a counter biasing spring member, the trigger and the pintle-bearing member are pivoted together to slide a shearing edge against and through the cable strap at the tool barrel.

Description

DESCRIPTION OF THE PRIOR ART

Many forms of tensioning and cut-off tools are known in the prior art. These have employed pliers-type, two-handle mechanisms, hydraulic mechanisms and many forms of hand-operated pistol-grip tools. In the pistol-grip types, lost motion members are generally used as motion-transmitting members, their motion transmission occuring when the settable tension has been reached. Many intricate linkages and mechanisms have been used.

In any such mechanisms, the goal is to produce a small, easily manipulated tool which can be manufactured inexpensively on a mass basis, in which the tension of the strap can be set to desired levels, and which is capable of sustained life under heavy usage conditions.

SUMMARY OF THE INVENTION

The present invention provides an improved, manually operated, pistol-grip tensioning and cut-off tool which can best be described briefly by describing its operation. An opening in the barrel or nose of the tool receives a strap and provides a stop against which the strap head rests, the strap body being looped about a body to be baled or bundled. The strap is passed through the strap head and inserted into the barrel of the tool. As the tool trigger is tightened, a spring-loaded member at the free end of a drawbar grips the strap. The drawbar is connected to the trigger by an intermediate link to pull the drawbar in response to pivotal movement of the trigger about a tensioning pivot. As the bar moves, the strap moves, tightening its loop about the body within the loop of the strap. As the loop tightens, tension in the strap increases. As the strap tension increases to a force greater than that exerted by a restraining spring, continued movement of the trigger couples the trigger to the spring-loaded member. The member pivots about a central axis drawing the trigger downwardly and pivoting a cut-off link to cause a shear blade to be driven past a shear edge disposed beyond the strap thereby cutting the strap at the tool nose.

It is, therefore, an object of our invention to provide a new and improved bale tensioning and cut-off tool.

It is a further object of the invention to provide a novel, simple and inexpensive cable strap tightening and cut-off tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a tool employing our invention, with the tool housing wall broken away to show the interior thereof;

FIG. 2 is a partial plan view of the tool of FIG. 1;

FIG. 3 is a side elevational view of the tool with a strap under tension;

FIG. 4 is a side elevational view of the tool with a strap fully tensioned and being cut off; and

FIG. 5 is a side elevational view of the tension adjusting assembly as used in our invention.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIG. 1, we show a tool 10 having its main frame 11 in the general shape of a pistol-grip or gun-shaped tool. The tool frame has a handle 12 and a barrel portion 14. The outer housing is broken away in FIG. 1 along the handle to show the frame and the interior components of the tool, the continuation of these components within the area covered by the housing, being indicated by dashed lines. A trigger 16 is pivoted within the barrel portion, the trigger being depressible under manual pressure toward the handle 12.

The function of the tool is to grip the tongue or strap 20 of a cable tie and tighten the strap about a bundle 22 of cable or wires while holding the head 24 or buckle of the strap against the outer end 30 of the barrel portion. When a set tension in the strap 20 is reached, a cutting head 32 is raised parallel to outer end 30 to shear the strap adjacent to the strap head.

The barrel end 30 of the frame 11 has an end plate 34 with a slitted clearance opening 40 for receiving an end of the strap 20 aligned for linear movement along the inner wall of plate 34, is cutting head 32. This cutting head has sharp dihedral upper edge normally positioned below the slit opening 40. Above slit opening 40 the barrel portion of frame 11 has a stationary retaining wall 42 forming the upper extremity of the barrel wall 42. A cutting head positioning member 44 is spaced from end plate 34 a distance sufficient to hold the cutting head relative to the plate. A finger 46 in member 44 rides in a suitable cutout within the cutting head body, thereby to align the cutting edge in its normal position relative to the slit opening. The member 44 is rigidly pinned to the barrel side wall to maintain its position relative to the barrel end 30.

The lower end of the body 52 of cutting head 32 terminates a distance above the bottom flange wall 50 of the barrel and is spaced therefrom. In the space between the body 52 and flange wall 50 is positioned the activating tip 54 of the pivotal cutting control lever 56. This lever is an elongated pivotal member which is pinned pivotally to the frame 11 intermediately along its length within the barrel portion such that on depression of handle end 58 of the lever 56, the actuating tip is raised to elevate the dihedral edge of cutting head 32 across the area of slit opening 40. This movement is accomplished in an abrupt snap action allowing the cutting edge to cooperate with the serrate edge of slit opening 40 and shear the straps.

The trigger operated linkage of the tool includes a drawbar 60 constrained to linear motion within the barrel. The drawbar as seen in FIG. 2 has two rigid side supports formed into a ladder-like drawbar.

In its at rest condition, the drawbar rests against the positioning member 44, the member also serving to cam strap gripping head 62 to its at rest position. A gripping head 62 is pivotally affixed to the drawbar at pivot 64 and has an upper serrated surface 65. With the gripping head in its normal position, an extension of slot opening 40 is formed between the gripping head and clamping wall 66, the clamping wall being rigidly connected to the drawbar for movement therewith.

A wire sear spring 70 mounted on pivot 64 biases the gripping head when the drawbar is moved away from member 44 to pivot the head toward engagement with clamp wall 66 and combinedly grip a strap tightly therebetween, as shown in FIGS. 3 and 4.

Drawbar 60 is constrained to linear motion (horizontally as shown in FIGS. 1, 3 and 4) by the two separated sections 72 of frame 11, also by supporting ledges opposite 72 (not shown) and at the handle end by its positioning within a slot 74 in the frame above the handle. A pivot pin 76 serves as the roller which is journalled within slot 74. The frame section 72 has an edge facing the tool barrel end 30 and an inclined face 78 extending from the edge to receive and divert the strap end out of the tool mechanism during the tensioning operation (as shown in FIGS. 3 and 4).

The pivot pin 76 also connects the drawbar to the trigger activated linkage through an intermediate connecting link 80 which is connected to the trigger 16 intermediately along its length. The trigger 16 may comprise a U-shaped cross section in its lower section, the base 82 of the U cross section being adapted to be held by the fingers of the person using the tool. The trigger design in this area is a matter of choice and may be any suitable shape.

At its uppermost end, the trigger is pivotally pinned to one end of a tension control link 90. The tension control link joins the trigger linkage to the tension adjustment assembly. Link 90, as mentioned, at one end is connected through pivot pin 92 to the trigger. The other end of the control link receives and holds a vertically extending arm of 93 of the main tension spring 94. As shown, control link 90 has a second opening 96 at the spring end, the opening 96 being an alternate connection for the arm 93. By selecting either opening 96 or receiver 98 (as shown) the mechanical advantages of the control link about its central pivot 110 may be set to either of two levels. Pivot 110 is secured to the frame 11 and rides within an elongated slot 112 in link 90.

As long as the holding force acting on control link 90 does not cause the spring to elongate, the link 90 assumes its normal position as shown in FIG. 1 and remains stationary, allowing the trigger to pivot about pin 92.

Also pinned to the frame 11 in pivotal fashion is cutter activating crank 114. This crank is a generally S shaped member, its pivotal connection to the frame 11 being within the handle 12. At roughly the center of the crank is a U-shaped recess 116. Within recess 116, rides a dowel 118 secured adjacent the inner end of cutting lever 56. The dowel rests freely within the recess, so that downward movement of the crank will depress the inner end of the lever and will raise the actuating tip 54. The crank is biased to its normal position (as shown in FIG. 1) by a compression spring 130, one end 131 of which rests against an embossed section of crank 114. The free end 134 of crank 114 rests engageably under pivot pin 92 for movement therewith.

The normal position of the linkage is further retained by the retaining finger 140. At its lower end finger 140 is pivotally pinned at 141 to frame 11. Adjacent the pin connection on finger 140 is an emboss which receives the other end 144 of spring 130 to bias the crank and finger relative to one another. The free end 146 of finger 140 remains on the upper side of pin 92. Thus compression spring 130 biases two members to normally position pivot pin 92 therebetween holding the pin in its normal position relative to control links 90.

The tension adjusting assembly (shown best in FIG. 5) includes the main tension spring 94, which, as mentioned previously, has its extending arm engaging an end of control link 90. The body 150 of spring 94 rests with a cylindrical passage in the hollow handle 12. The lower end 151 of spring 94 is secured to a central axial threaded shaft 152 for axial movement therewith. The shaft is mated within a threaded washer and retaining ring 154, the ring being affixed to the handle 12. Thus, when the shaft is rotated within ring 154, the lower end 151 of spring 94 responds and moves accordingly upwardly or downwardly relative to the fixed handle to correspondingly change the activating force on arm 93 necessary to elongate spring 94.

A tension adjusting knob is secured on the free end of shaft 152 below the base 16 of the handle. Rotation of the knob causes rotation of the shaft or stud 152 corresponding changes in the spring response level as mentioned previously. A suitable indicator pointer (not shown) extending through a vertical slot (not shown) in the handle, the pointer being secured to the spring for linear movement therewith, may be used to indicate spring tension settings viewable from the exterior of the tool. Such indicating pointers are, of course, well known in the art.

With the tool at its normal condition as shown in FIG. 1, a cable strap 20 is inserted into slitted opening 40 and the strap head is positioned adjacent to end plate 34 of the tool barrel.

The trigger is then squeezed toward the handle in the usual pistol-grip manner. As the trigger is depressed, it pivots about pin 92 and through link 80 moves drawbar 60 linearly. As the drawbar moves (to the right in FIGS. 1, 3 and 4), gripping head 62 is freed of its engagement with member 44 and under the bias exerted by spring 70 pivots toward clamp wall 66 to grasp the cable strap between serrated surface 65 and the clamp wall. Thus, as the drawbar is drawn toward handle 12, the end of strap 20 is pulled further through strap head 24, tightening the strap about the wire bundle 22. Spring 130 compresses, maintaining the cutter actuating crank separated from its activating engagement with lever 56.

As long as the force transmitted to control link 90 by the trigger assembly does not exceed the elongating force set for spring 94, link 90 remains stationary and the trigger continues to tighten the strap in the manner shown by FIG. 3. When the tension on the strap causes the force on the link 90 to become greater than the force necessary to elongate main spring, 94 the spring will elongate. Elongation of the spring allows the link 90 to slide a limited amount about its pivot 110 to the position of FIG. 4. The link 90 will also pivot a limited amount downwardly at its end connected to the trigger. This movement of link 90 causes a snap action movement to rapidly drive crank 114 downwardly and into actuating engagement with cutting lever 56. Lever 56 pivots to impel cutting head 32 upwardly through the strap, shearing the strap 20 against end plate 34. On completion of the shearing action, the tension on the trigger assembly is automatically released, restoring the mechanism automatically to the normal position.

Claims

We claim:

1. A strap tensioning tool having a pistol-grip body, a trigger member, an intermediate linkage coupled to said trigger member, a strap gripping head, drawbar means linking said trigger member to said gripping head to cause said head to grip a strap received within said head, means constraining said drawbar to substantially planar movement, said drawbar means responsive to movement of said trigger member in a tensioning direction for advancing said head to tension said strap between the advancing head and an entry nose of said tool, said intermediate linkage normally restrained in a stationary manner during tensioning of the strap, cutter means normally decoupled from said intermediate linkage and said trigger member, means responsive to the tension in said strap exceeding a predetermined level for driving said trigger member and said intermediate linkage in a cutting direction, and means actuated by the driving of said trigger member in said cutting direction for coupling said cutter means to said intermediate linkage for causing said cutter means to shear the strap adjacent said entry nose.

2. A tool as claimed in claim 1, wherein there is pivot control means maintaining said trigger member in pivotal motion to slide said drawbar in a tensioning direction, said pivot control means responsive to said tension reaching said predetermined level for itself moving to drive said trigger member in said cutting direction.

3. A tool as claimed in claim 2, wherein said pivot control means includes an intermediate mounting means and a tension spring normally holding said intermediate mounting means against movement to permit said trigger member to move and slideably advance said drawbar.

4. A tensioning and cut-off tool for tightening a strap about a bundle and through a buckle-like head of said strap, said tool including a wall member for positioning thereagainst said strap head, a slit in said wall for passing the strap body into said tool, a reciprocable tensioning member means constraining said tensioning member to reciprocating substantially tensioning movement, said tensioning member including a strap gripping head adjacent said slit to receive a strap therein, means normally biasing said head in an open condition relative to a strap passed through said slit, a manually operable handle member, means linking said handle member to said tensioning member to control the movement of said tensioning member, said gripping head responsive to movement of said tensioning member for assuming a gripping condition about a strap, means for pivoting said handle member about a first pivotal axis whereby to move said tensioning member planarly and increase the tension on said strap, and means responsive to the tension on said strap exceeding a predetermined amount for causing said handle member and said linking means to rotate about a second pivotal axis, and shear members engaged by said handle member on its rotation about said second pivotal axis for advancing in shear motion against said strap adjacent said slit.

5. A tool as claimed in claim 4, wherein said rotation causing means includes a pivotal linkage and a tension spring normally resisting movement of said pivotal linkage, and means for adjusting the elongation force of said tension spring relative to said predetermined amount of tension, said spring on elongation thereof releasing said pivotal linkage to rotate said handle member about said second pivotal axis.

6. A strap tensioning and cutting tool comprising a frame, an opening in one end of said frame for receiving a headed strap for tensioning, a gripping head disposed adjacent said opening, a slide bar for holding said gripping means, and a trigger member pivotal on depression thereof, a link interposed between said trigger member and said slide bar to move said slide bar in a strap tensioning direction on pivotal movement of said trigger member, a second link engaging said trigger member at one end of said second link, means for pivotally mounting said second link to the frame intermediately of said second link, bias means secured to the other end of said second link for restraining said second link from pivotal movement, said trigger means on continued depression after overcoming the bias imposed by said bias means for driving said second link in pivotal movement about its pivotal mounting, and a cutter arm normally decoupled from said links and said trigger member, and a third link responsive to said continued depression of said trigger member for coupling said cutter arm to said trigger member and driving said cutter arm to sever the strap adjacent said opening.