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Publication numberUS3658006 A
Publication typeGrant
Publication dateApr 25, 1972
Filing dateFeb 5, 1969
Priority dateFeb 5, 1969
Publication numberUS 3658006 A, US 3658006A, US-A-3658006, US3658006 A, US3658006A
InventorsHannagan Harold W, Nistler Gordon A
Original AssigneeExplosive Tech
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Explosively actuated egress and ingress device and method
US 3658006 A
Abstract
Explosively actuated egress and ingress device having a case formed of relatively light-weight material with an outer surface and having a linear-shaped explosive positioned within the case adjacent to the outer surface and with a resilient backing material in the case. A pliable gathering material may also be provided within the case to the rear of the linear-shaped explosive charge. The method includes the positioning of the devices for cutting large holes.
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United States Patent Nistler et al.

1451 Apr. 25, 1972 EXPLOSIVELY ACTUATED EGRESS 2,779,278 1/1957 Klotz,.ir. ..lO2/2O AND INGRESS DEVICE AND METHOD 2, ,833 6/1957 'Sweetmam- --l02/20 2,797,892 7/1957 Ryan 102/24 HC [72] Inventors: Gordon A. Nlstler, vacwllle Harold W. 2,982,209 5/1961 Borcher I I "102/27 x Hamil", Napa'bmm Cam 3,190,372 6/1965 Johnson 102/24110 [73] Assignee: Explosive Technology, lnc., Fairfield, 3,296,968 67 hu man t a1 ..l02/27 Calif. 3,323,544 6/1967 Francis ..l02/24 HC 3,374,737 3/1968 Pike ..l02/24 HC [221 Feb-5,1969 3,477,372 11/1969 McFemn eta ..102/24 11c [2l] Appl.No.: 796 770 Primary Examiner-Verlin R. Pendegrass Related p Data AnorneyFlehr, Hohbach, Test, Albritton & Herbert [63] Continuation-impart of Ser. No. 740,645, June 27,

l968,abandoned. [57] ABSTRACT Explosively actuated egress and ingress device having a case [52] U.S. Cl ..l02/24 HC formed of relatively light weight material with an outer sub 2 face and having a linear-shaped explosive positioned within 1 0 l the case adjacent to the outer surface and with a resilient backing material in the case. A pliable gathering material may [56] References cued, also be provided within the case to the rear of the linear- UNITED STATES PATENTS shaped explosive charge. The method includes the positioning of the devices for cutting large holes. 2,682,220 6/l954 Hagensen ..l02/24 2,715,365 8/1955 Godchaux et al.. 30 Claims, 28 Drawing Figures 55 1: =5 t -53 it 1 \Il ll ,-W' 7 4 P 1 3 l l/ 3 l I I 1i l I H "1 Hi {11 54 4', I I

1 a J it n/ x 7 2 I \1, i w 5 v; A L [P312 i PATENTEDAPR 25 I972 SHEET 1 BF 8 INVENTOR Gordon A. Nlsner Harold W Hon gan PATENTEUAPR 2 5 m2 SHEET 2 BF 8 lll l=l I INVENTORS Gordon A. Nistler BY Harold W Hannagan :21:24, Wag iatforneys PATENTEUAPR 25 I972 SWEET 3 [1F 8 m .m l

INVENTORS Gordon A. Nisfler BY HOfO/ d W Hannagan W1 Attorneys PATENTEI] APR 2 5 I972 SHEET 8 [IF 8 INVENTORS Gordon A. Nisfler Harold W Hanna BY gan W 71 mforneys PATENTEDAPR 25 I972 3, 658 O06 SHEET 7 OF 8 L N \l d Q N II M INS: 823 g 0 t INVENTORS Gordon A. Nistler BY Harold W. Hannagan PATENTEDAPR 2 5 m2 SHEET 8 BF 8 Fi g. 28 147 INVENTORS Gordon A. Nisrler y Harold W Hannagan 27%, W, n4 M y W Alforneys EXPLOSIVELY ACTUATED EGRESS AND INGRESS DEVICE AND METHOD CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 740,645, filed June 27, 1968, and now abandoned.

BACKGROUND OF THE INVENTION In emergency operations of various types, it frequently becomes necessary to gain immediate access to the inside of a structure such as a building, ships hold, grain elevator, aircraft fuselage, or the like, for the purpose of rescue, fire fighting or similar types of emergency operations. Forced entry of this general type normally has employed the use of conventional or specialized hand implements such as axes, saws, pry bars, battering rams and oxyacetylene cutting torches. More recently, motorized saws have been used. Although each of these implements or devices has been used for a number of years, they all have disadvantages particularly in that most of them require considerable time to use and are frequently ineffective or hazardous for one reason or another. For example, chain saws are now used rather extensively by fire fighters for emergency roof ventilation and the like. A not uncommon incident is for the saw blade to encounter live electrical wires when cutting into the structure. Such an occurrence is obviously dangerous to the operator of the chain saw. In an attempt to overcome these disadvantages, explosives, per se, have been utilized in an attempt to gain forcible entry into structures. However, these attempts have largely utilized techniques associated with rock blasting and have generally employed stick dynamite or blasting gelatin. The result is inefficient utilization of energy, relatively unsafe operation, and inordinate damage to the structure being breached. Also in such operations it is necessary to clear personnel and bystanders to a remote location from the point of explosion because of the fragment hazard and the concussion.

There is, therefore, need for a new and improved explosively actuated egress and ingress device.

SUMMARY OF THE INVENTION AND OBJECTS The explosively actuated egress and ingress device for forming an opening in a wall-like structure having an exposed surface consists of a case which is formed of a relatively lightweight material and which has an outer surface adapted to be placed in engagement with the exposed surface of the wall-like structure in which the opening is to be cut. A linear-shaped explosive charge is positioned in the case adjacent to the outer surface and lays along at least a portion of a line which defines the perimeter for the opening to be cut into the wall-like structure. A resilient backing material is mounted in the case to the rear of the linear-shaped charge with a pliable gathering material which is also provided in the case to the rear of the linear-shaped explosive charge.

In general, it is an object of the present invention to provide an explosively actuated egress and ingress device and method which can be utilized by relatively unskilled personnel.

Another object of the invention is to provide a device of the above character which can be rapidly and readily placed in operation. 7

Another object of the invention is to provide a device of the above character which is relatively fool-proof.

Another object of the invention is to provide a device of the above character which can be readily manufactured and which is relatively inexpensive.

Additional objects and features of the invention will appear from the following description in which the preferred embodiments are set forth in detail in conjunction with the accompanying drawings.

BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 1 is a perspective view showing an explosively actuated egress and ingress device incorporating the present invention for use in cutting an opening in a rolling door.

- wall for cutting a hole into the wall.

FIG. 7 is a top plan view of the device shown in FIG. 6 with the flaps in an open position.

FIG. 8 is a top plan view of still another embodiment of a device incorporating the present invention.

FIG. 9 is a plan view of the under side of the lid of the device shown in FIG. 8.

FIG. 10 is a cross-sectional view taken along the line 10- 10 of FIG. 8.

FIG. 11 is a cross-sectional view taken along the line 11-11 of FIG. 8.

FIG. 12 is a bottom plan view of the device shown in FIG. 8 with certain portions broken away.

FIG. 13 is a top plan view of the device shown in FIG. 8 with the center section of the lid broken out and with portions of the lid broken away.

FIG. 14 is a cross-sectional view taken along the line 14-14 of FIG. 12.

FIG. 15 is a cross-sectional view taken along the line 15-15 of FIG. 14.

FIG. 16 is a cross-sectional view taken along the line 16-16 of FIG. 14.

FIG. 17 is a greatly enlarged view, partially in cross section, of the means utilized for firing the device shown in FIG. 8.

FIG. 18 is a top plan view of still another embodiment of a device incorporating the present invention.

FIG. 19 is a bottom plan view of the lid of the device shown in FIG. 18.

FIG. 20 is a cross-sectional view taken along the line 20-20 of FIG. 18.

FIG. 21 is a bottom plan view of the device shown in FIG. 18 with certain portions broken away.

FIG. 22 is a top plan view of the device shown in FIG. 18 with certain parts removed therefrom.

FIG. 23 is a top plan view of the device shown in FIG. 18 with the center section broken out.

FIG. 24 is a top plan view of a combination of devices incorporating still another embodiment of the invention showing the manner in which they would be arranged for cutting a large hole in a roof or similar structure.

FIG. 25 is a side elevational view of one of the devices shown in FIG. 24 with certain portions broken away.

FIG. 26 is a cross-sectional view taken along the line 26-26 of FIG. 25.

FIG. 27 is an isometric view of a package assembly showing the manner in which the explosively actuated ingress and egress devices can be packaged for shipment.

FIG. 28 is a partial cross-sectional view'taken along the line 28-28 of FIG. 27.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS The explosively actuated egress and ingress device consists of a case 11 which is formed of a relatively light-weight nonfragmentable material such as cardboard. The case is formed in two box-like parts 12 and 13. Both the box-like parts 12 and 13 are provided with the spaced parallel sidewalls 14 and spaced parallel endwalls 16 and a top or a bottom wall 17. The part 12 is slightly larger than the part 13 so that the two parts can be telescoped together as shown in FIG. 3 to provide a complete enclosure. The two parts 12 and 13 are bonded together by a suitable means such as an adhesive and, in addition, the edges can be sealed with tape 18 so that the case is substantially water-proof.

The case 11 is provided with a substantially planar outer surface formed by the bottom wall 17 of the inner box-like part 13 which is adapted to be placed against the exposed surface of the wall-like structure in which an opening is to be cut.

A linear-shaped explosive charge 21 is disposed immediately adjacent the inner surface of the bottom wall 17 of the inner box-like part 13 of the case 11. The linear-shaped explosive charge can be of any suitable type as, for example, Jetcord manufactured and sold by Explosive Technology, Inc. of Fairfield, California. As is well known to those skilled in the art, such a linear-shaped explosive charge consists of a shaped metal member 22 of a suitable material such as lead which is substantially V-shaped or chevron shaped in cross section to concentrate the explosive effects. The open side of the V" or chevron is positioned so that it faces in the direction in which the cut is to be made. The explosive charge 23 is embedded within the metal member 22 and extends longitudinally of the metal member. The explosive charge can be of any suitable material such as RDX, PETN, TNT or any powdered explosive. The linear-shaped explosive charge 21 is arranged in a predetermined pattern as, for example, the perimeter of the opening which is to be cut with the device. Thus, as shown in F 16. 2, the linear-shaped explosive charge 21 can be formed into a circle to provide a circular opening of the desired size.

A resilient backing material 26 of a suitable type such as a closed cell syntactic plastic foam is applied to the rear of the charge 21. A supporting and/or gathering material 27 which is relatively pliable also is provided to the rear of the explosive charge and either can be provided within the backing material 26 or can surround the outside of the resilient backing material. Thus, as is shown in FIG. 3 of the drawings, the gathering material 27 can take the form of a rubber sheet which envelopes the outer surface of the syntactic foam which serves as a resilient backing material 26. The resilient backing material is in the form of a circle and is generally rectangular in cross section as can be seen in FIG. 3. The gathering material 27 is generally U-shaped in cross section and covers the side and the rear surfaces of the resilient backing material. Alternatively, the gathering material 27 can be a woven fabric such as woven Nylon or it can be in the form of chopped Nylon roving dispersed within the syntactic foam which makes up the resilient backing material. As can be seen, the resilient backing material 26 with the gathering material 27 substantially fills the outer peripheral portions of the case 11 but leaves a cylindrical space 28 in the center.

Means is provided for detonating the linear-shaped explosive charge and consists of a non-electric blasting cap 31 of a conventional type which is embedded within the resilient backing material 26 and is in engagement with the linearshaped explosive charge. A confined detonating cord 32 of a conventional type is connected to the blasting cap 31 and extends outwardly through a hole 33 in the gathering material 27 and is connected to a firing mechanism 34. The firing mechanism 34 consists of a housing 36 formed of a suitable material such as plastic. The housing 36 is generally cylindrical and is of a size which can be readily grasped by hand. The confined detonating cord extends into a bore 37 provided in the housing. A percussion detonator 38 is mounted in the housing 36 and is in engagement with the end of the detonating cord 32. The detonator 38 is adapted to be detonated by firing pin 39 slidably mounted in the housing 36 and yieldably urged in a direction toward the detonator 38 by a coil spring 41. The spring 41 is mounted in a well 42 provided in the housing 36 and has one end engaging a collar 43 provided on the firing pin 39.

The firing pin 39 is normally retained out of engagement with the detonator by a trigger member 46 which is slidably mounted in a bore 47 in the housing 36 extending at right angles to the bore 37. The trigger mechanism 46 is provided with a bore 48 which is of such a size so that the firing pin 39 can travel therethrough. The trigger member 46 is also provided with a slot 49 which opens into the bore 48 and is adapted to receive the pointed tip 390 of the firing pin 39 as shown in FIG. 4 Spring means in the form of a waffle spring 51 is provided for yieldably urging the trigger member outwardly so that the slot 49 of the trigger member is engaged by the pointed end 39a of the firing pin. Safety means is provided for preventing operation of the trigger member until it is removed and consists of a safety pin 52 which extends through the housing 36 and through the trigger member 46. The firing pin 39 is provided with a pull ring 53 to permit cocking of the firing pin against the force of the spring 41. The firing mechanism with the confined detonating cord is normally stored within the cylindrical recess 28 provided within the case 11.

The top wall of the box 17 is perforated to provide two flaps 17a and 17b which can be opened to expose the recess 28 and to permit access to the firing mechanism 33 and the confined detonating cord 32. Before use of the device, the flaps 17a and 17b are in closed positions with the firing mechanism stored within the recess 28.

If desired, means may be provided in or on the case for securing the case to the wall in which a hole is to be cut. Thus, for example, four magnets 56 can be provided in the four opposite corners of the case 11 adjacent the bottom wall 17 of the inner part 13. These magnets are of such strength and size so that they can readily support the device upon a steel door or the like in which a hole is to be cut.

Let it be assumed that an emergency has arisen and that it is desired to cut a hole in a steel door which is the steel door 61 shown in FIG. 1 in the drawings in the sidewall of a building 62. The user would quickly grab one of the devices and would merely place it against the steel door and it would be held on the steel door in the desired position by the magnets 56 within the case. The perforated flaps 17a and 1712 would be broken by the fist and the flaps 17a and 17b opened as shown in FIG. 3 to permit immediate access to the firing mechanism 33. The operator would then quickly grab the firing mechanism and pull out the confined detonating cord 32 to the extent of the length of the cord which in a typical device can be 30 feet to permit the operator to move a sufficient distance to permit safe operation of the device.

The safety pin 52 is then removed and the trigger 46 is actuated against the force of the spring 52 by the same hand which is holding the firing mechanism 46 to permit the spring 41 to force the firing pin through the hole 48 and to detonate the percussion detonator 38. The percussion detonator 38 ignites the cord which detonates the blasting cap 31. The detonation of the blasting cap 31 detonates the linear-shaped explosive charge which immediately cuts through the steel door 61 against which it is placed to provide a relatively large hole so that a man can crawl through the same and enter the building. All this can be accomplished in a very few minutes because the device is a relatively light-weight device and can be easily manipulated because of its practical size and bulk. It also provides the necessary degree of safety.

When the linear-shaped charge is detonated, the high pressure gases or shock waves which are generated are dispersed and attenuated by the geometry of the voids that constitute the macroscopic air holes in the foam. This has the overall effect of normalizing the pressure points emanating from the explosion and thereby extends the pressure release duration and reduces the over-pressure in the proximity of the explosion. The plastic foam also serves to decelerate the fragments that result from the fragmentation of the metal sheath of the linearshaped explosive charge. It also collects the fragments within the foam in which they are embedded. If and as the foam structure begins to fracture into large segments, the foam presents a significant aerodynamic drag so that the fragments, in their foam encapsulation, travel only a few feet. The gathering or supporting media around the foam minimizes the breakup of the foam and increases the size of the broken-up foam sections and thereby reduces the distance that they will be propelled. Thus, it has been found that the device can be operated with great safety at a distance of as little as 30 feet.

Although the invention has been described with a closed cell foam, other foams can be utilized. A closed cell foam is desirable because it will not absorb water as readily as will an open celled foam. If an open celled foam were to be used, it would lose its shock attenuating characteristics if it absorbed water. It has been found that a closed cell foam which has been foamed to a density of approximately 6 lbs. per cubic foot is particularly satisfactory. It has also been found that the lower limit of effectiveness is approximately 3 lbs. per cubic foot and that the upper limit is approximately 10 to lbs. per cubic foot at which time the foam becomes prohibitively heavy and its effectiveness as a shock attenuator is reduced.

Although there has been described one particular way of initiating a linear-shaped charge, other conventional ways can be utilized. However, the use of electrical blasting caps may be undesirable in the vicinity of high voltageelectric lines in an emergency situation. Time-delayed fuses also may be undesirable where people may be wandering around such as at a fire.

Another manner for attaching the device to a wall is shown in FIG. 6 in which the device has been provided with a handle 66. With such a handle, a nail 67 can be pounded into the wall 62 and the device quickly hung on the nail and then operated in the same manner as hereinbefore described to blast a hole quickly in a wall.

The device as disclosed can be constructed to cut any desired size and shape of hole. Thus, as shown in FIG. 7, a generally rectangular opening can be cut if desired.

Another embodiment of the explosively actuated egress and ingress device is shown in FIGS. 8-17 and is particularly adapted for use on steel rolling doors. It cuts an opening which is square in shape and has a suitable size such as a 2 ft. square. The opening is cut by cutting an inverted U in the steel rolling door which creates a flap which will fold down as soon as the device is actuated to create the square opening. There is no necessity for cutting across the bottom of the rolling door because of the construction of the rolling door which permits the flap to drop downwardly along the fold line of one of the slats of the rolling door.

The device shown in FIGS. 8-17 consists of a housing or case 71 which is formed of a relatively light-weight non-fragmentable material such as molded polystyrene. The case 71 is formed in two parts: one of which is a box 72, and the other of which is a lid 73, both of which are formed of polystyrene. The box 72 is of a unitary construction and is provided with a bottom wall 76 which is generally planar as shown in FIG. 10. The box 72 is also provided with spaced parallel upstanding side walls 77 and 78 and spaced parallel upstanding end walls 79 and 81 which join with the walls 77 and 78 to provide a rectangular enclosure. A first or inner compartment 82 is formed within the confines of the walls 77, 78, 79 and 81 by spaced parallel side walls 83 and 84 which are spaced from and parallel to the walls 77 and 78 and an end wall 86 which is spaced from and parallel to the end wall 79. The walls 83, 84 and 86 cooperate with the end wall 81 to provide the four-sided first or inner compartment 82.

A U-shaped second or outer compartment 87 is formed between the walls 83, 84 and 86 forming the inner compartment 82 and the walls 77, 78, 79 and 81 which form the outer extremities of the box 72. A pair of spaced parallel reinforcing walls 88 and 89 extend between the walls 79 and 87. The bottom wall 76 of the box 72 is provided with a Ushaped raised portion 76a which is generally V-shaped in cross section as can be seen in FIG. 10 and which is centered with respect to the portion of the bottom wall that forms the outer or second compartment 87. This raised portion 76a is generally U- shaped in plan as is the compartment 87. A recess 91 which is generally V-shaped in cross section is formed in the bottom wall 76 and underlies the raised portion 76a of the bottom wall so that it also extends the entire length of the U-shaped outer or second compartment 87. The recess 91 opens outwardly through the outer surface of the bottom wall 76.

A lid 73 has the same configuration as the box 72 and is adapted to fonn a cover for the open side of the box 72. The cover is provided with means whereby a predetermined section 73a of the cover may be broken out without destroying the remainder of the lid. Thus, the cover 73 has been provided with a recess 94 which is generally V-shaped in cross section as can be seen from FIG. 10 which is in the form of a rectangle in plan as seen in FIG. 9. The recess 94 is positioned so that the rectangle which is formed thereby generally overlies the first or inner compartment 82 to facilitate access to the compartment 82. In order to'facilitate ready break-out of the section 73a which is defined by the recess 94, additional recesses 96 and 97 which are also V-shaped in cross section are provided in the bottom'side of the lid 73 and form an X" in plan as shown in FIG. 9. The lid 73 is also formed with a downwardly depending bulging portion 73b which also forms a rectangle in plan that is generally the same size as the first or inner compartment 82 so that it will fit within the first or inner compartment as shown in FIG. 10 and to thereby position the lid 73 on the box 72. The lid 73 is provided with a planar outer surface 98 which is generally parallel to the outer surface of the bottom wall 76 of the box 72. As can be seen from FIG. 8, the lid 73 can be provided with suitable printing to indicate the section 730 which is to be broken out and a description where the lid should be punched by hand to break out the section 730.

A linear-shaped explosive charge 101 is disposed within the recess 91 provided in the bottom wall 76 of the box 72. As explained previously, this linear-shaped explosive charge can be of any suitable type such as Jetcord manufactured and sold by Explosive Technology, Inc. of Fairfield, Cal. As shown particularly in FIG. 15, such a linear-shaped explosive charge consists of a shaped metal member 102 of a suitable material such as lead which is substantially V-shaped or chevron shaped in cross section to concentrate the explosive effects. The open side of the V or the chevron is positioned so that it faces in the direction in which the cut is to be made. An explosive charge 103 is embedded within the metal member 102. The linear-shaped explosive charge 101 extends the entire length of the U-shaped recess 91 so that it generally underlies the outer or second compartment 87 of the box 72.

Means similar to that hereinbefore described is provided for detonating the linear-shaped explosive charge 101 and consists of a non-electric blasting cap 106 which is in engagement at one end of the linear-shaped explosive charge 101 as shown in FIG. 14. The blasting cap 106 is adapted to be detonated by a confined detonating cord 107 of a conventional type. The blasting cap 106 and the confined detonating cord 107 are disposed in a recess 108 provided in the bottom wall and which continues into an opening 109 provided in the bottom wall 76 so that the detonating cord 107 can extend upwardly into the box 72 within the inner compartment 82 as shown in FIG. 13. As can be seen from FIG. 13, a substantial length of the confined detonating cord as, for example, 30 ft., is coiled within the inner compartment 82 in the form of a figure 8. The end of the cord 107 is provided with a fitting 111 which contains a percussion initiator 113 which, when acted upon by a firing mechanism 114, will initiate a primer 116. The primer 116 initiates an intermediate charge 117 which, in turn, initiates the confined detonating cord 107. The outer end of the fitting 111 is provided with threads 118 and is adapted to have threaded thereon the firing mechanism 114. The fitting 111 on the end of the cord 107 and the firing mechanism 114 are mounted in a slotted holder 121 secured to the bottom wall 76 of the box 72. The firing mechanism 114 consists of a tubular member 122 which is threaded onto the fitting 111. A firing pin 123 is slidably mounted within the member 122 and is provided with a pin 124 which extends outwardly at right angles therefrom through a slot 126 provided in the tubular member 122. A knob 127 is mounted on the pin and is adapted to be grasped by the hand. A spring 128 mounted within the tubular member yieldably urges the firing pin 123 in a direction towards the percussion initiator 113. The spring is held in place by a knurled cap 129 threaded into the end of the tubular member 122. It can be seen that by grasping the knob 124 and moving it out of one portion of the slot 126 and releasing the same, the spring will urge the firing pin 123 into rapid engagement with the percussion initiator 113 to initiate the same.

In FIG. 17 a line extension 131 has been provided to permit firing of the explosively actuated ingress and egress device from a greater distance. This line extension 131 consists of a length of confined detonating cord 132. The length is chosen so that there is more than ample distance for initiating the explosively actuated ingress and egress device from a distant location as, for example, 100 ft. One end of the extension line 131 is provided with a fitting 111 similar to that hereinbefore described. The other end of the line is also provided with a fitting 133 in which the confined detonating cord 132 is mounted. In addition, there is provided an intermediate charge 134 which ignites the primer 136. The primer 136 initiates the percussion initiator 113 which is carried by a coupling 137 which is threaded onto the fitting 111 provided on the cord 107. The coupling 137 is retained on the fitting 133 by a snap ring 138. With the extension line 131 constructed in this manner, it can be readily seen that one or more extension lines can be utilized to place the necessary distance between the explosively actuated ingress and egress device and the person operating the same.

The linear-shaped explosive charge 101 forms a thin wedgeshaped jet of energy when it is initiated. Means is provided for depleting this jet in the event that the linear-shaped explosive charge 101 is inadvertently initiated. This means consists of a relatively thin wire 141 which is disposed in the open V- shaped recess 142 of the linear-shaped explosive charge 101 and extends the entire length of the linear-shaped explosive charge. A portion of the wire 141 extends outwardly from the box 72 and is formed into a loop 143 which carries a warning tag 144. The warning tag states that the wire 141 must be pulled completely out of the box 72 so that it will not defeat the jet which is created by the linear-shaped explosive charge. The wire 14] can be formed of any suitable material. However, it should have certain characteristics. For example, it should be relatively ductile so that it can be readily pulled out of the recess 142 of the linear-shaped explosive charge. In addition, it should have a relatively high density. Lead has been found to be particularly desirable for this purpose. It is believed that the wire 141 serves to defeat the jet because the wire 141 is, in fact, positioned along the line at which the jet would be formed. In addition, the wire 141 serves as a shock attenuator or dispersant to prevent shock waves from forming. Thus, the wire 141 serves to defeat the essential elements which are required to form a jet from a linear-shaped explosive charge. Since the jet is defeated, there will be substantially no cutting action from the linear-shaped explosive charge in the event it is inadvertently initiated.

Even though a single wire 141 has been utilized for the three-sided configuration of the explosive charge 101, it should be appreciated that, if desired, particularly if it is very difficult to pull a wire extending the entire length of the recess 142, that a separate wire could be provided for each side of the V-shaped configuration of the explosive charge 101. When this is the case, three places would be provided for removing the wires from the box 72. A face panel 146 of a suitable material such as cardboard is secured to the bottom side of the bottom wall 76 by suitable means such as cement and serves to hold the jet defeating wire 141 in place as well as to hold the linear-shaped explosive charge 101 in place.

A backing material 148 is provided in the outer or second compartment 87 and instead of the plastic foam hereinbefore described, a relatively light granular material in the form of Vermiculite is used. The compartment 87 is vibrated so that the compartment is completely filled with Vermiculite and so that it will not settle and leave any empty space during transportation of the device. After the compartment 87 has been filled, a layer of cardboard 149 is placed over the Vermiculite in the compartment 187 as shown in FIG. 10. This cardboard layer 149 is utilized to hold the Vermiculite in place until the lid 73 can be secured to the box 72 by suitable means such as by the use of an adhesive. A handle 151 is mounted in the box 72 and is formed of a suitable material such as :4 inch Nylon rope. The Nylon rope extends through holes 152 provided in the walls 88 and in the wall 87 and the ends of the same are fastened together by metal splicers 153. The splicers serve to form the Nylon rope into a continuous loop so that it serves as a handle 151.

Operation and use of the explosively actuated ingress and egress device shown in FIGS. 8-l7 may now be briefly described as follows. Let it be assumed that it is desired to cut a hole in a steel rolling door to obtain quick access to the fire within a building in which the door is mounted. The fireman or other individual utilizing the device carries the same by the handle and uses a magnet which carries a hook (not shown) which is secured to the door and then the handle 151 is secured to the hook. The device always must be positioned on the door so that the face plate 146 faces the door and is fiat against the vertical surface of the door.

Alternatively, as hereinbefore described, the device can be provided with magnets which would hold the device to the door in the appropriate place. As soon as this has been accomplished, the fireman uses his fist and strikes the weakened section 73a which says punch here shown in FIG. 8. This causes the polystyrene to break along the lines of the V= shaped grooves 94, 96 and 97 to provide a rectangular opening 154. The section which has been broken out can be removed to expose the cord 107. At this time, the jet defeating wire 141 is removed by pulling on the loop 143 as shown in FIG. 13. As soon as the wire 141 has been removed, the fitting 101 and the firing mechanism 114 are removed from the holder 121. It should be appreciated that the jet defeating wire 141 can be removed before the device is mounted on the door. The fireman then uncoils the cord 107 and goes to a remote location and threads the firing mechanism onto the fitting 111.

After the cord 107 has been payed out to its full length and without pulling the device away from the door in which the cut is to be made, the operator then faces away from the device and operates the firing mechanism by releasing the firing pin. This causes detonation of the cord in the manner hereinbefore described and also causes initiation of the linear-shaped explosive charge. This causes the desired hole to be cut into the rolling door. The hole will be cut between the two sides and the top of the door which will form a flap which will drop downwardly along the closest articulated joint of the rolling door to thereby permit ready entry into the building.

It has been found that the construction as shown in FIGS. 8-17 is particularly advantageous. One difference from that of the previous embodiment is that the groove which contains the linear-shaped explosive charge 101 is on the side of the bottom wall 76 rather than on the inside. This is advantageous for a number of reasons. For example, this makes possible the formation of a V-shaped groove in the outer surface of the bottom wall and ensures that the linear-shaped explosive charge will be positioned in the middle of the backing material 148. In addition, this construction provides means for isolating the jet which is generated by the linear-shaped explosive charge from the backing material 146. This is important because this prevents the backing material from seeping down into the recess 142 in the linear-shaped explosive charge which could interfere with the effectiveness of the jet which is formed by the linear-shaped explosive charge.

It has been found that the Vermiculite utilized as the backing material is particularly effective for capture of fragments and for attenuation of the shock waves and noise. The utilization of a plastic such as polystyrene for the case 71 has also been found to be particularly desirable. It is relatively economical and is particularly effective when it has a density ranging from approximately 2 to 4 lbs. per cubic foot. Such a density gives adequate strength to the case and when the linear-shaped explosive charge is detonated will not break into fragments which are dangerous. This material is also particularly advantageous for the dissipation of shock waves and noise.

The plastic handle which is utilized has an advantage in that if the door on which the device is mounted becomes red hot, the handle will melt and the device will drop to the ground and then can be removed at a later time. Even if the device should become very hot so that it begins to burn, it normally will not explode and will merely be consumed.

It should be appreciated that although in the embodiment of the invention shown in FIGS. 8-17, the device has been formed so that linear-shaped explosive charge 101 only extends along three sides of the opening which is to be cut, the device can be readily modified to extend the linear-shaped explosive charge to the fourth side. When this is the case, the device can be utilized for permitting entry, egress or ventilation through the barriers of masonry, wood, metal, plaster, etc. It is particularly applicable for forming ventilation holes in roofs and the like. It can be used for rapidly cutting such a hole in a roof merely by throwing the device onto a roof from an aerial ladder or platform. This is accomplished by first removing the jet defeating wire 141 and then breaking out the weakened front panel portion 73a. The firing line or cord 107 is then removed. Then, holding the cord 107 in one hand, the device can be thrown onto the roof. In the event that the device lands upside down on the roof, it can be pulled back by the firing line and tossed onto the roof again until it lands right side up. Once the device has been properly positioned on the roof, the firing mechanism is attached and then the device can be initiated in the manner hereinbefore described to rapidly cut a hole in the roof.

In the event a situation arises in which it is impossible for a fire fighter to get close enough to position the device, the device can be attached to the end of an aerial ladder and then by utilizing an extension line 131, the aerial ladder can be utilized for positioning the device and thereafter it can be initiated by operation of the firing mechanism to cut a hole in the roof without any danger to the firemen.

Still another embodiment of the explosively actuated ingress and egress device is shown in FIGS. 18-23. This embodiment also consists of a case 161 which has a circular configuration rather than the rectangular configuration of the case 71 in the previous embodiment. The case 161 consists of a box 162 and a lid 163, both of which are formed of a suitable material such as molded polystyrene. The box is provided with a bottom wall 164 and an annular side wall 166. A centrally disposed well 167 is formed as a part of the box 162 by a circular upright wall 168 formed integral with the bottom wall 164. An outer annular compartment 169 is formed between the wall 168 and the side wall 167. A linear-shaped explosive charge 171 is mounted in a recess 172 provided in the outer surface of the bottom wall 164. The recess 172 is formed in a raised portion 164a of the bottom wall. The linear-shaped explosive charge 171 is constructed in the manner hereinbefore described and has mounted therein a jet defeating wire 173. A face plate 174 of fiberboard is mounted on the back surface of the bottom wall 164 and serves to hold the jet defeating wire 173 and the linear-shaped explosive charge 171 in place. A loop 176 is formed on the end of the wire 173 and is provided with a warning tag 177. The linear-shaped explosive charge 171 is substantially continuous and is in the form of a circle which generally underlies the center of the outer compartment 169 formed in the box 162.

Means is provided for detonating the linear-shaped explosive charge 171 which is of a type that is similar to that hereinbefore described. It consists of a blasting cap 178 which is disposed in a recess 179 provided in gusset 181 that is formed integral with the inner side wall 168 and the bottom wall 164. The blasting cap extends through a hole 182 (see FIG. 2) and is in direct contact with the linear-shaped explosive charge as shown in FIG. 20. The blasting cap is connected to a confined detonating cord 183 which is also disposed in the recess 179 and extends upwardly above the well 167. A backing material 186 such as Vermiculite is disposed in the outer annular compartment 169 and fills the same. A layer of cardboard 187 is mounted in the box 162 flush with the top of the wall 168 and also rests upon an annular shoulder 188 provided in the side wall 166. This cardboard layer 187 serves to keep the Vermiculite in place. The cord 183 extends above the cardboard layer 187 and is looped about in a space 189 provided above the cardboard layer 187 as shown in FIG. 23. The loops of the cord are held in place by suitable means such as strips of masking tape 19]. The cord is provided with a fitting 192 similar to the fitting 111 and which is mounted in a slotted holder 193 mounted upon the cardboard layer 187. The holder 193 also carries a firing mechanism 194 identical to the firing mechanism 114.

The lid 163 is cemented in place on the box 162. It is provided with a weakened section 163a by the use of a circular V- shaped slot 167 and a pair of diametrically extending slots 197 and 198 which form a cross to facilitate ready break-out of the weakened section. The lid is also provided with an annular reinforcing portion 163b which extends downwardly and, in addition, to reinforcing the opening 199 which is formed when the weakened section 163a is broken out, also serves as a means for registering the lid on the box 162.

A handle 201 for carrying the device and also for hanging up the device when it is desired to operate the same. The handle is formed from a suitable material such as Nylon rope which extends through holes 202 provided in reinforcing bosses 203 formed integral with the side wall 166 and the ends of which are fastened together by splices 204.

The device which is shown in FIGS. 18-23 is operated in much the same manner as the embodiments hereinbefore described. It is positioned on the wall or surface on which the opening is to be cut. From the configuration of the linearshaped explosive charge, it can be seen that a circular cut is made. Typically, this device can make a hole 12 inches in diameter. Such a hole permits introduction of a stream of water through a masonry, plaster, metal or wooden barrier or makes it possible to unlock a steel fire door from the inside. Even though a small opening is made with a device such as shown in FIGS. 18-23, this does not preclude making a larger opening with a device of the type hereinbefore or hereinafter described should this become necessary.

The embodiment of the device shown in FIGS. 18-23, however, does include an additional feature which is not included as a part of the embodiments hereinbefore described. This is the provision of the center well 167 which is designed to receive a supplemental explosive charge. Such a supplemental charge may be desirable where it is necessary to fonn a hole in a relatively thick masonry or concrete wall. Typically, a sheet explosive 206 is mounted in the bottom of the well 167 after the weakened section 163a has been removed from the lid 163 and after the cord 183 has been removed. An extension line 207 having a blasting cap at one end and having a percussion detonator and intermediate charge on the other end of the type hereinbefore described is connected to the sheet explosive 206 as shown in FIG. 20. Then, the extension line 207 leads out of the well and is placed in recess 208 provided in another gusset 209 extending radially outwardly from the wall 168. The extension line 207 then extends through an opening (not shown) similar to the opening 182 and makes contact with the linear-shaped explosive charge 171. Thus, it can be seen that at the time the linear-shaped explosive charge is detonated, the extension line 207 will be detonated to cause detonation of the sheet explosive 206 which will cause the creation of a center point of over-pressure which will greatly aid in cutting the hole through a thick wall of masonry or concrete.

Still another embodiment of the explosively actuated ingress and egress device is shown in FIGS. 25 and 26 which can be characterized as a straight embodiment. The device 211 consists of a housing or case 212. The housing or case 212 consists of a box 213 and a lid 214. The box has a rectangular configuration and is provided with a bottom wall 216, spaced parallel side walls 217 and 218 and spaced parallel end walls 219 and 221 which form an elongate compartment 222. The bottom wall is provided with a centrally disposed raised portion 216a which extends longitudinally of the box and which is provided with a recess which receives a linear-shaped explosive charge 223 opening through the bottom side of the bottom wall 216. A jet defeating wire 224 is mounted in the open V of the explosive charge 223 in the manner hereinbefore described. The wire is provided with a loop 226 which carries a tag 227. A fiberboard face plate 228 is secured to the bottom side of the bottom wall 216 and retains the wire 224 and the linear-shaped explosive charge 223 within the recess in the bottom wall. Backing material 231 is provided in the compartment 222 and is of a suitable type such as Vermiculite. The lid 214 covers the open side of the box 213 as shown in FIGS. 25 and 26 by suitable means such as an adhesive and seals the backing material 231 within the box. The box 213 and lid 214, as in the previous embodiments, can be formed from polystyrene.

Means is provided for detonating the linear-shaped explosive charge and consists of a blasting cap 232 which is adapted to be initiated by a confined detonating cord, both of which are disposed in a recess provided in the bottom wall and which abut one end of the linear-shaped explosive charge 223. A fitting 234 is provided on the outermost end of the cord 233 and is adapted to receive a firing mechanism 236 of the type hereinbefore described.

The device which is shown in FIGS. 25 and 26 can be manufactured in any suitable length. For example, it may be desirable to provide lengths of 2, 4, 6 and 8 ft. which can be utilized in combination to enable one to cut a large, rectangular hole as, for example, a hole 8 ft. long by 4 ft. wide, or any other size which can be cut by using various combinations of the devices 211 shown in FIGS. 25 and 26.

Although the device which is shown in FIGS. 25 and 26 has been shown as having a rectangular configuration, an elongate device can also readily be manufactured by utilizing a housing or case which has a semi-circular configuration and in which the bottom side of the semi-circular configuration is enclosed by a lid which can carry the linear-shaped explosive charge.

Operation and use of the device which is shown in FIGS. 25 and 26 may now be explained in connection with FIG. 24. Let it be assumed that it is desired to cut a large hole as, for example, 8 ft. by 2 ft., in the roof of a burning building to ventilate the same. To accomplish this, the devices 211 would normally be used in pairs. Thus, as shown in FIG. 24, two of the devices 211 which are 8 ft. in length would be placed on the roof of the building in spaced parallel relationship. The firing lines or cords 233 would be coupled into a snap coupler 237 which, in turn, would be connected to an extension line 238 of the type hereinbefore described. A firing mechanism 234 would then be mounted on the end of the extension line. As soon as the operator has removed himself to a safe distance, the firing mechanism 234 could be operated to detonate the extension line 238 and the lines 233 to set off the devices 211. Actuation of the two devices 211 would form two parallel cuts extending in one direction in the roof. As soon as this has been accomplished, two additional devices 211 which are 2 ft. in length are mounted over the ends of the cuts which have already been made in the roof and are interconnected to a firing mechanism 234 in the same manner that the previous pair of devices was connected. The operator then detonates the other two devices 211 to cause two additional cuts to be made in the roof at right angles to the cuts which have previously been made to complete cutting the rectangle and to permit the section of the roof which has been cut out to drop inwardly and to thereby vent the roof. In positioning the last two devices 211, the operator must be sure that the cuts which are to be formed by the two devices 211 will overlap the two cuts which have previously been made so that there will be a continuous cut all around the section of the roof which is to be cut out so that the roof section will drop inwardly.

From the foregoing, it can be seen that a very usable assembly consists of a pair of the straight devices 211 which have their confined detonating cords interconnected into a single end fitting which can be detonated by the use of a single firing mechanism. This facilitates placing the assembly into use very rapidly merely by taking two of the units and placing them in spaced apart positions and then rapidly detonating the same to provide two elongate cuts. The opening can be completed merely by utilizing another pair of the devices to make two cuts between the two cuts which have already been formed to complete the formation of the opening.

In order to facilitate use of the explosively actuated ingress and egress devices, it is desirable and almost necessary that such devices be capable of meeting a class C designation under the Bureau of Explosive regulations. This permits it to be shipped in the same classification as shot gun ammunition and permits it to be moved by common carriers. In FIGS. 27, 28 and 29, there is shown a package assembly which is utilized for packaging the explosively actuated ingress and egress devices so that they will meet the class C designation described above. Two of the explosively actuated ingress and egress devices 241 of any of the types hereinbefore described as, for example, the type which is shown in FIGS. 8-17 are packaged as a unit as shown in FIGS. 27 and 28. Each of the devices 241 is packaged in its own shipping container or box 242. Each box 242 consists of a bottom section 243 and a top section 244. Each section is provided with a bottom wall and upstanding side walls and are arranged so that they telescope within each other as shown in FIG. 28. A shock absorbing pad 246 formed of a suitable material such as polystyrene having a density of approximately l lb. per cubic foot and one-half inch in thickness is provided within the box 242 adjacent the bottom or cutting side of the device 241. It will be noted that with the pad in place, the side walls of the two sections 243 and 244 overlap substantially throughout the entire lengths. The two sections 243 and 244 are fastened together in a suitable manner such as by gummed craft paper 247.

After the devices 241 have been packaged in the corrugated boxes or containers 242, the two boxes 242 are stacked one above the other in such a manner so that the bottom sides or the cutting sides of the two devices 241 face each other. In other words, the cutting sides of the devices 241 are in juxtaposition. It should be appreciated that the devices 241 are packaged with their jet defeating wires in place so that one device 241 will not be initiated sympathetically in the event of inadvertent detonation of the other device.

The two boxes 242 are placed in a large outer third box or shipping container 251 which is also formed of two sections 252 and 253 which are provided with a bottom wall and upstanding sidewalls and which are formed so that they telescope within each other as shown in FIG. 28. Again, the side walls of the sections 252 and 253 overlap throughout substantially all portions thereof. The two sections 252 and 253 are fastened together by suitable means such as a filament tape 254.

The boxes 242 and the box 251 are formed of fiberboard which meets an ICC approved classification 12H for containers.

The packaging which is shown in FIGS. 27 and 28 has been found to be capable of providing adequate protection so that in the event of inadvertent detonation of one of the devices, severe damage will not result to adjacent structures. Lethal fragments are not created because of the construction of the devices themselves as hereinbefore pointed out and also because of the packaging material which is utilized for packaging the devices for shipment. The fiberboard construction of the boxes also serves to provide a substantial fragmentshielding function. In tests, it was found that even if the devices were thrown into a fire, they would not explode but only burn. Driving heavy trucks over the same would not cause them to explode. Similarly, firing rifle bullets into the same or dropping the same would not cause them to explode. Also, the device can withstand relatively high temperatures before burning. Thus, it can be utilized on any surface which is 800 F. or less. Even at the highest temperature it will not begin to burn for several minutes which is more than ample time to position and fire the device.

In packaging the straight device which is shown in FIGS. 25 and 26, the devices can be packaged in a similar manner with the cutting faces in juxtaposition to each other. It can be seen that if the straight devices are semi-circular in cross-section, that two of them can be readily combined and shipped in a circular tube which would be very convenient.

In all the embodiments it can be seen that the backing material is faced directly in the compartment behind the linear-shaped explosive charge. Alternatively, if desired, the backing material can be placed in elongate plastic bags and then the bags placed in the compartment. This has the advantage in that the bags will confine the backing material and will prevent it from spreading throughout the device. This will be particularly advantageous during the construction of the devices.

It is apparent from the foregoing that there has been provided an explosively actuated device which can be readily and rapidly used for obtaining either egress from or ingress into a building. This is particularly advantageous for fire fighting and other emergency situations. The device is relatively simple and economical in construction and can be operated by relatively unskilled personnel.

The device is one which can have a number of configura tions and thus is very versatile for cutting any size and type of hole. It can be utilized in many dangerous locations without danger to the personnel utilizing the same. Because of its many features, the device can be characterized as a forceable entry tool.

We claim:

1. A self-contained explosively actuated ingress and egress device for forming an opening in a wall-like structure having an exposed surface, said device being detonatable from a safe distance from said wall-like structure and comprising an enclosing case normally surrounding the operative components of said device, said case being formed of a relatively lightweight substantially non-fragmentable material having an outer surface adapted to be placed in engagement with the exposed surface of the wall-like structure in which the opening is to be cut,-a linear shaped explosive charge positioned within the case adjacent said outer surface and lying along a line which defines at least a portion of the perimeter of the opening to be cut into the wall-like structure, a resilient backing material mounted within said case to the rear of the linear shaped explosive charge and surrounded by said case, and integral self-contained means normally disposed within and enclosed by said case for detonating said linear shaped explosive charge; said last named means including an elongated confined detonating cord operatively connected with said explosive charge, and a firing mechanism operatively connected with said confined detonating cord, said detonating cord and said firing mechanism normally being enclosed within said case but being selectively removable from the confines of said case and actuatable from a distance when said explosive charge is to be detonated.

2. A device as in claim 1 together with a pliable gathering material mounted in the case to the rear of the linear shaped explosive charge.

3. A device as in claim 2 wherein said gathering material is in the form of a flexible sheet surrounding said resilient backing material.

4. A device as in claim 1 wherein said case is formed with a means permitting an opening to be readily formed within the case to permit access to the firing mechanism and to the confined detonating cord.

5. A device as in claim 1 wherein said case is formed of a pair of telescoping box-like sections.

6. A device as in claim 2 wherein said linear shaped explosive charge, said backing material and said gathering material are in a general alignment with the perimeter for the opening to be cut into the wall-like structure.

7. A device as in claim 1 wherein said resilient backing material is a closed cell syntatic foam.

8. A device as in claim 1 wherein said case is provided with flaps which can be opened to permit access to said firing mechanism and said confined detonating cord.

9. A device as in claim 1 together with means mounted on the case to facilitate securing the case to the wall in which the opening is to be cut.

10. A device as in claim 1 wherein said firing mechanism is comprised of a housing, a bore in said housing for receiving said confined detonating cord, a detonator mounted in the housing and engaging the cord, a firing pin slidably mounted in the housing, a spring means mounted in the housing for yieldably urging the firing pin in the direction toward the detonator, a trigger mounted in the housing being movable between the first and second positions, said trigger in said first position preventing said firing pin from moving into engagement with said detonator and in second position permitting said firing pin to move into engagement with the detonator and spring means yieldably urging the trigger into the first position.

11. A device as in claim 1 together with a centrally disposed compartment formed in said housing, said compartment being adapted to receive an additional explosive charge, said case being formed to permit access to said compartment.

12. A device as in claim 11 wherein said case and said linear shaped explosive charge are formed so that said additional explosive charge can be connected to said linear shaped explosive charge for detonating said additional explosive charge.

13. A device as in claim 12 wherein said case is formed with a compartment overlying the centrally disposed compartment for receiving the elongate confined detonating cord and the firing mechanism.

14. A device as in claim 1 wherein said resilient backing material is Vermiculite.

15. A device as in claim 1 wherein said case is formed of a molded plastic having a compartment disposed behind the linear-shaped explosive charge and wherein said backing material is disposed in said compartment.

16. A device as in claim 1 together with a centrally disposed compartment formed in said housing, an additional explosive charge in said centrally disposed compartment, and means for detonating said additional explosive charge connected to said elongate confined detonating cord.

17. A device as in claim 1 wherein said case is formed of plastic and wherein said case has a weakened section in one wall, said weakened section being capable of being broken out to permit access to the firing mechanism and the confined detonating cord.

18. A device as in claim 1 together with safety means disposed within the linear-shaped explosive charge for defeating the jet of the linear-shaped explosive charge when it is detonated.

19. A device as in claim 18 wherein said linear-shaped explosive charge is generally V-shaped in cross section and having a generally V-shaped open recess extending longitudinally of the same and wherein said safety means is in the form of wire disposed in the open recess of the linear-shaped explosive charge.

20. A device as in claim 19 together with means carried by said wire to facilitate ready removal of the same from the linear-shaped explosive charge.

21. In an ingress and egress device adapted to be explosively actuated for forming an opening in a wall-like structure having an exposed surface, a case formed of a relatively light-weight, substantially non-fragmentable material and which has an outer planar surface adapted to be placed in engagement with the exposed surface of the wall-like structure in which the opening is to be cut, a linear-shaped explosive charge carried by the case adjacent to the outer surface and lying along at least a portion of the line forming at least part of the perimeter for the opening to be cut into the wall-like structure, safety means within the case removably mounted adjacent the linearshaped explosive charge for defeating the jet created by detonation of the linear-shaped explosive charge prior to removal of said safety means from adjacent said explosive charge, a resilient backing material carried by the case and disposed to the rear of the linear-shaped explosive charge, and integral self-contained means disposed at least partially within said case for selectively detonating said linear-shaped explosive charge.

22. A device as in claim 21 wherein said case is formed with a compartment to the rear of the linear-shaped explosive charge and wherein the backing material is disposed in the compartment to the rear of the linear-shaped explosive charge.

23. A device as in claim 22 wherein said backing material is in the form of Vermiculite.

24. A device as in claim 21 wherein said linear-shaped explosive charge is substantially V-shaped in cross section and has an open V extending longitudinally of the same and wherein said safety means is in the form of a wire disposed in the open V."

25. A device as in claim 24 together with means secured to the wire for facilitating removal of the wire from the linearshaped explosive charge.

26. A device as in claim 21 wherein said linear-shaped explosive charge is positioned along a substantially straight line.

27. A device as in claim 21 in which said means for detonating the linear-shaped explosive charge is normally disposed entirely within and enclosed by said case within a space provided therein to receive said means for detonating the linearshaped explosive charge.

28. A device as in claim 27 wherein said case is provided with a weakened section which is adapted to be broken to gain access to the means for detonating the linear-shaped explosive charge.

29. In an assembly of the character described, first and second devices adapted to be explosively actuated, each of said devices comprising a case formed of a relatively lightweight, substantially non-fragmentable material and which has an outer surface adapted to be placed in engagement with the exposed surface of the wall-like structure in which the opening is to be cut, a linear-shaped explosive charge carried by the case adjacent to the outer surface and lying along at least a portion of a line which defines at least a portion of the perimeter for the opening to be cut into the wall-like structure, safety means within the case removably mounted adjacent the linearshaped explosive charge for defeating the jet created by detonation of the linear-shaped explosive charge prior to removal of said safety means from adjacent said explosive charge, a resilient backing material carried by the case to the rear of the linear-shaped explosive charge, means carried by each of the cases for detonating the linearshaped explosive charge carried thereby, and means interconnecting said means for detonating whereby both of said devices may be initiated substantially simultaneously.

30. An assembly as in claim 29 wherein said devices are substantially straight and are adapted to be positioned in spaced parallel positions whereby when they are initiated, they will cut two relatively straight parallel lines.

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Classifications
U.S. Classification102/307, 102/310
International ClassificationF42B3/00, F42B3/08
Cooperative ClassificationF42B3/08
European ClassificationF42B3/08