Explosive cutter for cables and the like

Oct. 28, 1969

D. J. PECK

3,474,533

EXPLOSIVE CUTTER FOR

Filed May 17. 1967

CABLES AND THE LIKE

Sheets-Sheet 1

<img file="US3474533A_D0001.tif" />

Oct. 28, 1969

D. J. PECK

3,474,533

EXPLOSIVE CUTTER FOR CABLES AND THE LIKE

<img file="US3474533A_D0002.tif" />

3,474,533

Patented Oct. 28, 1969

United States Patent Office

2

3,474,533 EXPLOSIVE CUTTER FOR CABLES AND THE LIKE

Donald 3. Peck, Price, Utah, assignor to Etco, Incorporated, Murray, Utah, a corporation of Utah Filed May 17, 1967, Ser. No. 639,205 Int. Cl. B26b 15/00, 13/00, 9/00

U.S. CI. 30—228 7 Claims

ABSTRACT OF THE DISCLOSURE

A tool for cutting bundled-type electrical cable and the like, including an explosive powered cutter blade, a fixed blade, special safety guards to prevent injury to a user, and a safety discharge port for safely venting spent gases from the explosion generated to move the powered cutter blade.

BRIEF DESCRIPTION

This invention relates to explosive powered cutting tools and is particularly concerned with such tools usable to cut electrical cable and the like.

In electrical cable stringing operations, wherein large size “bundled” conductors or cables are used, it is frequently necessary to cut the cable to a desired length or to provide a smooth cut that will enable it to be spliced.

The bundled cable will usually be made up of a steel ⁰core around which smaller lines are wrapped and will be covered with aluminum. Each of the smaller lines may be made up of many even smaller copper wires. The cable being cut may, therefore, have a diameter of two inches or more and be made from a number of different types ^Jof material and be very difficult to handle.

In the past a number of explosive cutter tools have been developed for many special purposes, and at least one has been developed for cutting cables and another has been intended for use in cutting electrical wires or conductors.

U.S. Patent No. 2,454,528, for example, shows an explosive powered cable cutter, wherein a section of cable is discharged from the end of the cutter like a bullet. _4gU.S. Patent No. 2,716,813 shows a cutter for electrical wires or conductors wherein a revolving cylinder carries cartridges so that they can be positioned to be fired by a firing pin triggered by operation of a long operating handle.

Nevertheless, the explosive tools heretofore known are not satisfactory from either a safety standpoint, or an operation standpoint, for use in cutting the large size bundled conductors that are now frequently used.

It is for these reasons that I have developed an explo- _ggsize powered tool for cutting even large size bundled conductors effectively, and with a maximum of safety to the user.

Principal features of the present invention are the special blade arrangement that repeatedly provides smooth θθ cuts through the different materials used in the cables, i.e., aluminum, steel, and copper, and the special safety devices used to prevent injury to a user. These safety devices include a single shot loading cylinder; cocking means for the powered cutting blade arranged to be automatically disconnected and moved away from such blade, so that it does not travel with the blade; no powered parts external to the tool; hand guards to reduce the possibility of a user’s fingers being injured while placing a conductor between the blades; and shields to prevent exhaust gases γθ from burning the user.

The tool is made to be easily disassembled for cleaning, repair, or replacement of parts and utilizes a special, inexpensive ejector mechanism for removing spent cartridges.

There is shown in the accompanying drawings a specific _g embodiment of the invention representing what is presently regarded as the best mode of carrying out the generic concepts in actual practice. From the detailed description of this presently preferred form of the invention, other more specific objects and features will become apparent.

THE DRAWINGS

FIG. 1 is a pictorial view of a tool of the invention partially broken away for clarity;

FIG. 2, a vertical section taken on the line 2—2 of 15 FIG. 1;

FIG. 3, an enlarged, fragmentary, bottom view of the cartridge loading end portion of the tool, showing the firing chamber open;

FIG. 4, a fragmentary front elevation as viewed from 20 the line 4—4 of FIG. 3; and

FIG. 5, an enlarged pictorial view of the cocking mechanism, partially broken away for clarity and with the cocking handle shown in its rearmost position in full lines and in its forward position by broken lines.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT

Referring now to the drawings:

In the illustrated preferred form of the invention, the explosive cutter, shown generally at 10, includes a pistol grip handle 11, a firing mechanism, shown generally at 12, a piston housing 13 and a blade housing 14.

Pistol grip 11 includes a usual handle 15 and trigger guard 16 and also includes a tang 17 projecting rearwardly therefrom. The piston grip is permanently affixed to the firing mechanism 12 such that trigger guard 16 reaches around trigger 18 in usual fashion to keep the trigger from being inadvertently pulled.

Trigger 18 is pivoted at 19 to the housing 20 of firing mechanism 12, and a spring 21, positioned in a well 22 formed in the housing, biases the trigger such that sear 18α thereon will catch a shoulder 23 on an enlargement 24α of a firing pin plunger 24, when the plunger is pulled to the rear against the bias of spring 25. When trigger 18 is pulled sear 18α is lowered and spring 25, which is mounted between shoulder 24α and a plug 26 threaded into the end of the bore in housing 20 in which the plunger is positioned, biases the plunger forward so that eccentric pin 27 on the face of shoulder 23 will be pushed through hole 28 in the face of housing 20 to strike and explode a cartridge inserted in the bore of the plunger cylinder 13.

A knob 29 is affixed to the rear of plunger 24 to be gripped as the plunger is pulled back until sear 18α holds the plunger in position. An inverted U-shaped member 30 is fixed to the knob and straddles tank 17 to prevent turning of plunger 24, so that pin 27 will be held in proper alignment with hole 28. A spring 31 is compressed by knob 29 as plunger 24 moves forward and biases the plunger back slightly, so that pin 27 does not get stuck in hole 28. When the cartridge C (shown in phantom only in FIG. 3) is exploded, the gases act on piston 33 to drive it away from the firing mechanism. A piston rod 34 has one of its ends connected to piston 33 and its other end connected to a movable or powered cutting blade 35. Piston 33 slides sealingly within a central bore 36 of the piston housing 13 until it abuts a collar 37 positioned in an enlarged bore 38 of the housing.

Collar 37 is biased against the housing at the opening of bore 36 by a spring 39 that is positioned between the collar and a shoulder 40 formed in a coupling 41 that connects blade housing 14 with the piston housing 13. Collar 37 is freely slidable in enlarged bore 38, so that

3,474,533 when piston 33 abuts collar 37 spring 39 is compressed and acts as a buffer to slow down and stop travel of the piston and to return the piston to the bore 36.

After the piston enters the enlarged bore 38, the gases from the exploded cartridge are exhausted through port 42 into a chamber 43, FIG. 1, and finally out port 44. In exhausting from bore 36 the gases must make a number of right angle turns and in so doing dissipate much of their energy and heat. In passing out port 44, downwardly away from the tool, they are directed safely away from the operator.

In the illustrated form of the invention, blade housing 14 is made from two sections 45 and 46, FIG. 1, secured together by bolts 47 and having mated, cable-receiving openings 45a and 46α, respectively, into which corresponding upwardly disposed openings 456 and 46Z&gt; lead for the insertion of cables to be cut.

A fixed replaceable blade 48, FIGS. 1 and 2, is secured by two of the bolts 47 in a recess provided therefor at the inner face of housing section 46. The movable blade 35 is slidably fitted within a corresponding recess provided therefor at the inner face of housing section 45, so as to slide into face-to-face overlapping relationship with the cutting end of fixed blade 48 when the cartridge is exploded. The opposing, cutting ends of the blades 35 and 48 are each concavely curved, so as to encompass a cable being cut, and their cutting edges 35α and 48α, respectively are bevelled outwardly, as at 35b and 48Z&gt;, to merge into elongate thin sections 35c and 48c of the blades. It should be noted that such thin sections are bordered by relatively thick, marginal, reinforcing blade portions 35d and 48d that are wholly integral therewith.

With this configuration the blades absorb impact in themselves and are actually forced together during cutting operations, because of the bevels 35b and 48έ. Moreover, they are strong enough to withstand cutting of the steel core of bundled cable, and the bevelled edges will readily cut through the relatively soft aluminum and copper surrounding the core substantially without undesirable deformation thereof. By making the cutting sections of the blade relatively thin, sharp cuts are assured. Blade breakage is prevented by the marginal reinforcement. The bevels 35b and 48&amp; are preferably slight, e.g. about fifteen degrees relative to the transverse cross-sections of the respective blades.

In use, a cartridge C is inserted into a cartridge-receiving bore 50, FIGS. 2, 3, and 4, at the end of central bore 36 that is adjacent the firing mechanism 13, and the firing mechanism, which is pivoted at 51 to the piston housing, is closed and locked by a latch 52, FIG. 3, that is biased by a spring 53 to catch a shoulder 54 on the piston housing 13.

The cocking handle 55 of a blade cocking device 56 is pulled toward the firing mechanism by the user of the device, and, as it travels rearwardly, its tongue 57 is cammed by a slot 59α in a tube 59 carried by the blade housing section 14, so as to pass through a slot 58 in the wall of housing section 45 and ultimately engage a shoulder 35e that is formed at the end of the thin section 35c of movable blade 35. Handle 55 is connected to a rod 55α, FIG. 5, that is slidable and rotatable within the tube 59, and this rod has one end connected to a spring 60, whose other end 60α is anchored to the end of the tube. Thus, once handle 55 has been used to pull blade 35 to its rearmost position and has been released, spring 60 will pull the handle forwardly and slot 59α will cam it downwardly, to disengage tongue 57 from movable blade 35. It is then only necessary to grasp knob 29 and pull back plunger 24 until sear 18α catches shoulder 23 to ready the tool for use.

The user should grasp handle 12 in one hand and grasp with the other hand a handle 61, FIG. 1, located above the piston housing and removably fastened to blade housing 14 by a wing nut 62. The cable to be cut should be inserted between the cutting edges of blades 35 and 48. When trigger 18 is pulled in the usual manner of firing a gun, firing pin plunger 24 will be released and firing pin 27 will strike and explode the cartridge, which forces piston rod 34 and movable blade 35 forwardly, by reason of the expanding gases, and cuts the cable.

The spent cartridge is displaced for removal by pivoting the firing mechanism with respect to the piston housing, as shown in FIGS. 3 and 4, which cams an ejector 62, pivoted at 63 to the piston housing, to partially eject the cartridge to a point where it is easily grasped by the operator.

Handle 55 is pulled rearwardly to reposition the blade 35, and the tool is ready for insertion of another cartridge and another operation.

Should the fixed blade 48 break, it is a simple matter to replace it by removing bolts 47. Movable blade 35 can be replaced by removing a pin 64, FIG. 2, that connects it to a clevis 65 at the end of piston rod 34.

As a safety precaution, a bar 66 is preferably provided as a rearward extension of housing 20 beyond the rearmost position of knob 29, so that, if the tool is dropped, the firing pin plunger 24 is protected by such bar 66 and tang 17 so that it is not inadvertently released or damaged.

A deflector shield 67, secured as by welding to housing 20, extends over housing 13 when the firing mechanism is locked thereto and prevents any blow-back of escaping gases into the face of the user.

Guards 68 and 69, FIGS. 1 and 5, projecting outwardly from housing sections 45 and 46, respectively, protrude far enough from the sides of the tool to guard against inadvertent placing of parts of the body of a user close to the cutting blades. They therefore serve as safety devices against injury to fingers and other parts of the body.

It should be realized that various kinds of cable, other than electrical, etc., can be cut by the tool of the invention. Thus, structural steel strand cables of high strength, wire ropes, steel rods, bolts, and the like can all be cut by the tool.

Whereas there is here illustrated and specifically described a certain preferred construction of apparatus which is presently regarded as the best mode of carrying out the invention, it should be understood that various changes may be made and other constructions adopted.