US3780689A

US3780689A - Self-cocking explosively actuated cable cutter

Info

Publication number: US3780689A
Application number: US00163949A
Authority: US
Inventors: J Giebel; E Temple
Original assignee: Mine Safety Appliances Co
Current assignee: MSA Safety Inc
Priority date: 1971-07-19
Filing date: 1971-07-19
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25

Abstract

A cable cutter frame has a laterally opening recess near its front end for receiving a cable that can be cut by a chisel slidably mounted in the frame behind the recess when it is driven forward by an explosive charge. A plunger for actuating a firing pin is carried by the frame beside the recess and chisel and is slidable lengthwise of the frame. The plunger is provided adjacent the recess with a lateral notch that receives one end of a trigger extending transversely of the frame near the front of the recess in a position to be moved forward by a cable entering the recess, whereby to move the plunger forward against spring pressure. As the trigger is moved forward it withdraws from the notch, whereupon the plunger is driven rearwardly to actuate the firing pin. The anvil may be slidably mounted in the frame and provided with a shock absorber. The firing pin is preferably in the inner end of a transverse passage through the frame, in which a cartridge chamber is screwed.

Description

[ Dec. 25, 1973 SELF-COCKHNG EXPLOSIVELY ACTUATED CABLE CUTTER [75] Inventors: Joseph 11... Giebel, Pittsburgh; Ernest E. Temple, Murrysville, both of Pa.

[73] Assignee: Mine Safety Appliances Company,

Pittsburgh, Pa.

[22] Filed: July 19, 1971' [21] Appl. No: 163,949

[52] US. Cl 114/221 A, 89/1 B [51] Int. Cl. B63g 7/02 [58] Field of Search 89/1, 1 B; 114/221,

[56] References Cited UNITED STATES PATENTS 2,133,364 10/1938 Temple, Jr. 89/1 B 2,806,442 9/1957 Temple 89/1 B 2,396,732 3/1946 Wiener. 114/221 A 1,304,549 5/1919 DuPont 114/221 A 2,335,952 12/1943 Martin 114/221 A X 2,454,528 11/1948 Temple 89/1 B 3,111,927 11/1963 Temple et al.... 89/1 R X 3,320,669 5/1967 Chandler et al 89/1 B X Primary Examiner-Samuel W. Engle Attorney-Brown, Murray, Flick & Peckham [57] ABSTRACT A cable cutter frame has a laterally opening recess near its front end for receiving a cable that can be cut by a chisel slidably mounted in the frame behind the recess when it is driven forward by an explosive charge. A plunger for actuating a firing pin is carried by the frame beside the recess and chisel and is slidable lengthwise of the frame. The plunger is provided adjacent the recess with a lateral notch that receives one end of a trigger extending transversely of the frame near the front of the recess in a position to be moved forward by a cable entering the recess, whereby to move the plunger forward against spring pressure. As the trigger is moved forward it withdraws from the notch, whereupon the plunger is driven rearwardly to actuate the firing pin. The anvil may be slidably mounted in the frame and provided with a shock absorber. The firing pin is preferably in the inner end of a transverse passage through the frame, in which a cartridge chamber is screwed.

1 Claim, 8 Drawing Figures PATENTEI] UEEZS I973 mama NMU mm mw N L E i w My Jm wfi SELF-COCKING IEXPLOSIVELY ACTUATED CABLE CUTTER Explosively actuated cable cutters and the like are operated by tapping a firing pin against the detonator of an explosive charge, or by manually withdrawing a firing pin against spring pressure and then releasing it to set off the charge, or by cocking the tool and holding it in that condition by means of a flexible pin that releases the firing mechanism when the cable to be cut engages and separates the pin from the firing mechanism. Only this last system of operating a cable cutting tool can be operated at a distance from the operator, but it has the disadvantage that the tool may be fired accidentally or prematurely by something engaging the pin that holds the tool in its cocked condition.

It is among the objects of this invention to provide an explosively actuated cable cutter which is not cocked until a cable that is to be cut is in correct position in the cutter, which is cocked by the cable, which is safe to use, which has a long life and which can easily be disarmed.

The invention is illustrated in the accompanying drawings, in which FIG. 1 is a front view;

FIG. 2 is an enlarged longitudinal section taken on the line II-Il of FIG. 1;

FIGS. 3 and 4 are cross sections taken on the lines III- --III and IV-IV, respectively, of FIG. 2;

FIG. 5 is a view, similar to FIG. 2, of a modification;

FIG. 6 is a cross section taken on the line VI-VI of FIG. 5;

FIG. 7 is a view, similar to FIG. 2, of a further embodiment; and

FIG. 8 is a cross section taken on the line VIIIVIII of FIG. 7.

Referring to FIGS. 1 to 41 of the drawings, the metal frame I of the cutter or tool is long in comparison with its width and thickness and is provided with a passage extending through it from end to end. The rear end of this passage may be threaded to permit the tool to be mounted on one end of a long pole 2. The central portion of this passage forms a barrel 3 for a chiesel-like cutting member 4 with a cutting edge at its front end. The chisel normally is held in its rear position by means of a shear screw 5. The front end of the passage is closed by a screw plug 7 that forms an end wall for the frame passage. Engaging the inner end of this plug is an anvil 8 that is held in correct relation to the chisel by means of a positioning pin 9 extending through the wall of the passage. Directly behind the anvil the opposite sides of the frame are cut away and the front side of the frame is provided with a slot 10 that opens into the cable-receiving recess thus formed. To guide a cable 11 into the recess, the front side of the frame is provided with an inclined guide member 12.

The rear end of the barrel forms the breech of the tool, and a central bore through the breech receives an explosive cartridge 14. Directly behind the cartridge the frame is provided with a laterally opening rectangular recess 115, in which a breech block 16 is mounted. The end of the block at the back side of the frame is hinged to the frame by a hinge pin 17 so that the block can be swung out of the frame to expose the back end of the cartridge to allow it to be removed, as shown in FIG. 4. The breech block normally is held in operating position by a spring-pressed detent 18 projecting into a depression in the frame.

The breech block has a passage 20 through it aligned with the cartridge. Slidably mounted in the reduced from end of this passage is a firing pin 21, the rear end of which is provided with a head that is pivotally connected to the inner end of a pivoted lever 22 that extends laterally toward the back side of the frame in a slot 23 in the breech block. Near its free outer end of the lever is provided with a projection 24 that extends toward the front end of the frame in a bore 25 through the breech block. The firing pin normally is locked in its retracted position by means of a safety pin 27 extending through it and into the breech block. When, after this pin and another safety pin 28 have been removed, the lever projection 24 is struck by a springpressed plunger 29 carried by the frame, the lever drives the firing pin forward against the cartridge to detonate it.

The rod-like plunger 29 for moving the firing pin lever is slidably mounted in a bore 31 extending lengthwise of the frame at the back side of the barrel. The plunger is urged toward the lever by means of a coil spring 32 encircling the plunger between its enlarged front end portion and a shoulder in the frame bore. To normally hold the plunger out of engagement with the firing pin lever and to make the tool self-cocking, a trigger 33 is provided that has a front or outer end connected by a removable pivot pin 34 to the cable guide member 12 at the front side of the frame. The trigger extends inwardly through a longitudinal slot 36 in the front wall of the cable recess, across the recess and through another slot 37 in the back part of the frame and into a notch 38 in the side of the plunger. The position of the notch is such that as long as the trigger is projecting into it, the rod will be spaced from the firing pin lever.

After this tool has been loaded with a cartridge, it is prepared for use by removing the two

safety pins

27 and 28. The tool then is hooked over a cable by moving the tool laterally to cause the cable to enter the frame recess, where it will engage the trigger. Then, by pulling backward on the tool, the cable will swing the trigger forward in the frame, which will cause the trigger to slide the firing plunger forward in the frame and compress the coil spring 32. As the inner end of the trigger swings forward in an arcuate path, it is withdrawn from the notch in the plunger. The moment this occurs the plunger is released and is propelled rearwardly in the frame by its spring to cause it to strike the firing pin lever, which in turn drives the firing pin forward against the cartridge. The resulting explosion drives the chisel forward inthe barrel to sever the cable against the anvil. Since the trigger is likely to be ruined during the cable cutting, it is replaced by a new one and then the plunger is moved forward in the frame by means of a lateral projection 41 extending through a slot 42 in the back side of the frame. The plunger is moved far enough for the trigger to be able to enter its notch and then the plunger is allowed to move rearwardly again until stopped by the inner end of the trigger engaging the back wall of frame slot 37.

there is no danger of the tool being fired accidentally or before the cable is in correct position for cutting.

In the modification shown in FIGS. 5 and 6, the operation of the tool is similar to what has just been described, but the trigger is U-shape and straddles part of the frame 45. That is, the trigger is formed from two arms 46, one at each side of the frame, with their inner ends rigidly connected by a cross pin 47. The front or outer ends of the arms are mounted on a pivot pin 48 projecting from opposite sides of the frame, or from a cable guide member like member 12. The cross pin of the trigger extends through an arcuate slot 49 in the back side of the frame, located in such a position that when the trigger is at the rear end of the slot the pin will fit in a notch 50 in a spring-pressed firing plunger 51.

Although the breech block could be the same as that previously described, a modification is illustrated which has certain advantages. in this embodiment the cartridge 53 is not mounted in a longitudinal bore in the frame, but in an axial bore in a cylindrical breech block 54 provided with external screw threads. A short distance behind the chisel 55 the frame 45 is provided with a transverse cylindrical passage 56 that extends entirely through it, although the inner or back end of this passage is reduced in diameter. The breech block is screwed into the passage, and a firing pin 57 is slidably mounted in the reduced inner end of the passage. The pin projects out into the path of plunger 51, the front of which is notched to accommodate the pin and provide a sloping forward wall 58. At the inner end of the cartridge the breech block is provided with a radial port 59 that communicates with an opening 60 behind the chisel.

When a cable enters the frame recess 62 and swings the trigger forward, its cross pin 47 moves the plunger forward with it and compresses the plunger spring 63 until the pin leaves the plunger notch 50. At that moment the spring expands and drives the plunger rearwardly in the frame to cause the sloping wall 58 of the plunger to drive the firing pin against the cartridge. The resulting explosion drives the chisel forward in the barrel and severs the cable against an anvil 64. The anvil can be mounted the same way as described before, but a modification is shown in which it is slidably mounted in the frame and normally is spaced from the plug 65 in the front end of the frame passage by means of a shock absorber, preferably in the form of a short metal tube 66. When the anvil receives the impact of the chisel, it moves forward and crushes the tube, which thereby absorbs the shock to prolong the life of the tool. The crushed shock absorber can easily be removed and replaced by a new one.

If, after the tool has been fired, someone removes the breech block and the spent cartridge, reloads the breech block and then screws it back into the frame without first moving the plunger back to receive the inner end of the trigger in its notch 50, the act of screwing the breech block into the frame could press the firing pin against the side of the plunger and fire the cartridge. To prevent this from occurring, a safety device can be used which is in the form of a piston 68 pressed against the rear end of the plunger by a small coil spring 69 encircling the piston rod 70 between the piston and a ring nut 71 screwed into the rear end of the frame. The spring exerts just enough pressure against the plunger to move it back to the position it occupies while the trigger is in its notch. in this position the side of the plunger is spaced slightly from the firing pin, so there is no danger of a cartridge being detonated when the breech block is screwed into the frame.

in the further modification illustrated in FIGS. 7 and 8, the tool is equipped with a sliding trigger instead of a pivoted trigger. Thus, an anvil 75 is slidably mounted in the frame barrel 76 and normally is spaced from the screw plug 77 at the front end. A tubular shock absorber like the one previously described may be placed between them, or a cup-like shock absorber 78 can be screwed into the front end of the anvil with the open side of the cup facing the plug and spaced from it. The anvil is provided with a straight passage 79 extending through it from the front side of the frame to the back side. Slidably mounted in this passage is a trigger pin 81 that extends out of the back side of the anvil and into a slot 82 in the back side of the frame. The side of the pin normally engages the back wall of this slot and projects into a lateral notch 83 in a spring-pressed plunger 84. The forward wall of this notch slopes toward the front end of the pin. Also, the inner surface 85 of the frame at the outer end of the pin slopes forward and away from the anvil.

When a cable enters the frame recess 86 and the tool is pulled backward, the cable moves the anvil and trigger pin forward in the tool frame. The pin, in turn, moves the plunger forward against the pressure of coil spring 87, but since the inner end of the pin is pressed against the sloping wall of the plunger notch the pin is urged away from the plunger and along the sloping surface 85 of the frame. The latter surface is sloped enough to allow the pin to leave the plunger notch after the plunger spring has been compressed sufficiently. Then the plunger is driven forward to fire the cartridge. The trigger pin is protected and concealed within the tool at all times.

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. An explosively actuated cable cutter for operation by a cable to be cut, comprising a frame having a rear end and provided near its front end with a recess having an entrance at one side of the frame for admitting a cable to be cut, an anvil mounted in the frame between its front end and said recess, a chisel slidably mounted in the frame behind the recess and having a front cutting end, a firing pin in the frame behind the chisel for detonating an explosive charge to drive the chisel forward in order to sever a cable against the anvil, a plunger for actuating the firing pin carried by the side of the frame opposite said recess entrance and slidable lengthwise of the frame, the plunger normally being in an uncocked position and being provided with a lateral notch adjacent the front of the recess and facing said one side of the frame, the frame having a slot therein extending forward along the plunger from the notch, a rigid trigger extending transversely of the frame near the front of said recess in a position to be moved forward by a cable entering the recess behind the trigger, one end of the trigger extending through said slot and normally projecting into said plunger notch, means pivotally connecting the opposite end of the trigger to the between the frame and plunger adapted to be compressed by the forwardly moving plunger until the trigger leaves said notch and releases the plunger, whereupon the spring will drive the plunger rearwardly to actuate the firing pin.

Claims

1. An explosively actuated cable cutter for operation by a cable to be cut, comprising a frame having a rear end and provided near its front end with a recess having an entrance at one side of the frame for admitting a cable to be cut, an anvil mounted in the frame between its front end and said recess, a chisel slidably mounted in the frame behind the recess and having a front cutting end, a firing pin in the frame behind the chisel for detonating an explosive charge to drive the chisel forward in order to sever a cable against the anvil, a plunger for actuating the firing pin carried by the side of the frame opposite said recess entrance and slidable lengthwise of the frame, the plunger normally being in an uncocked position and being provided with a lateral notch adjacent the front of the recess and facing said one side of the frame, the frame having a slot therein extending forward along the plunger from the notch, a rigid trigger extending transversely of the frame near the front of said recess in a position to be moved forward by a cable entering the recess behind the trigger, one end of the trigger extending through said slot and normally projecting into said plunger notch, means pivotally connecting the opposite end of the trigger to the frame on a transverse axis, said one end of the trigger being swingable forward in said slot and the plunger being movable forward along said slot by said one end of the trigger from said uncocked position to cock the cutter, the trigger being retracted from said notch as tHe trigger is swung forward in said slot, and a spring between the frame and plunger adapted to be compressed by the forwardly moving plunger until the trigger leaves said notch and releases the plunger, whereupon the spring will drive the plunger rearwardly to actuate the firing pin.