US3216320A

US3216320A - Apparatus for excavating by means of explosives

Info

Publication number: US3216320A
Application number: US208531A
Authority: US
Inventors: Harold E Thomas; Jr Frank Vyzralek
Original assignee: Harvey Aluminum Inc
Current assignee: Harvey Aluminum Inc
Priority date: 1962-07-09
Filing date: 1962-07-09
Publication date: 1965-11-09
Anticipated expiration: 1982-11-09

Description

Nov. 9, 1965 H. E. THOMAS ETAL 3,216,320

APPARATUS FOR EXCAVATING BY MEANS OF EXPLOSIVES Original Filed Sept. 2 1958 4 Sheets-Sheet 1 FIG. I.

AGE/VT 1965 H. E. THOMAS ETAL 3,216,320

APPARATUS FOR EXCAVATING BY MEANS OF EXPLOSIVES Original Filed Sept. 2, 1958 4 Sheets-Sheet 2 FIG.3. I FIG-4'.

fivvavroas HAROLD 5 Ham/4s FHA/VA l/VZRALE/f, JR.

A GENT 1965 H. E. THOMAS ETAL 3,216,320

APPARATUS FOR EXCAVATING BY MEANS OF EXPLOSIVES 4 Sheets-Sheet Original Filed Sept. 2 1958 FIG. 5.

AGENT 1965 H. E. THOMAS ETAL 3,216,320

APPARATUS FOR EXCAVATING BY MEANS OF EXPLOSIVES Original Filed Sept. 2, 1958 4 Sheets-Sheet 4 F 'IG. 9.

United States Patent nuin (Incorporated), Torrance, Calif., a corporation of California Continuation of application Ser. No. 758 263 Se t 2 1958. This application July 9, 1962, Ser. No. 208 531 6 Claims. c1. s9 1) This application is filed as a continuation of application Serial No. 758,263 filed September 2, 1958 now abandoned.

This invention relates to a method and apparatus for excavating by means of explosives and is particularly concerned with the loosening and/or removal, partially or completely, of ground or earth formation. It is to be understood, however, that the method and apparatus herein disclosed is not to be limited to the loosening and/or removal of any particular substance or material since the method and apparatus has general utility and is useful in any case where it is desired to excavate or dig a hole, or the like.

In the drawings and throughout the specification the present invention is shown applied to the digging of a fox-hole for military purposes, which is ordinarily a time consuming and exhausting operation, as it is commonly carried out by military personnel. That is military personnel have been subjected to the strenuous Work of manually digging protective trenches and fox-holes, which not only consumes valuable time, but which also results in fatigue at critical times or moments. In any case, whether for military or for commercial purposes, it is highly desirable to facilitate excavating that would otherwise necessitate manual removal of material in order to form a trench, or hole, or any like opening.

A general object of this invention is to provide a method, and apparatus to carry out said method, whereby explosives are employed with facility to form excavations.

An object of this invention is to provide a method and apparatus for excavating with explosives that eliminates the usual preparation procedures. With the present invention it is merely necessary to initiate operation of the apparatus used in carrying out the method, all Without preliminary boring into or insertion of elements into the material being excavated.

Another object of this invention is to provide a method and apparatus whereby the formation of a bore is created by means of explosives for the insertion of an explosive charge therein that creates an excavation.

It is another object of this invention to provide a method and apparatus whereby an explosive charge is driven into a previously formed bore where it is then detonated to create an excavation by loosening and/or removing, partially or completely, the material being excavated.

It is still another object of this invention to provide a method and apparatus whereby an explosive charge is thrust into a previously formed bore by an explosive means, preferably a rocket-type motor, where said explosive charge is detonated to create an excavation.

Further, it is an object of this invention to provide an apparatus whereby the ignition of one explosive means operates to sequentially discharge other explosive means, whereby a bore is formed and after which an explosive charge is thrust into said bore and is then detonated to create an excavation.

Further, another object of this invention is to provide an apparatus of the character thus far referred to that is safe to handle and operate. The apparatus remains un- 3,216,320 Patented Nov. 9, 1965 armed until deliberately set for use, and the explosive charges involved are each individually safetied.

An object of the invention is to provide an apparatus of the character above referred to that is automatically armed when set in operating position. The explosive means are technically pre-armed by release of safeties when the apparatus is erected for operation and firing.

An object of the invention is to provide an apparatus of the character above referred to that automatically arms the explosive charge only when the said charge is accelerated and thrust into proper detonating position.

It is an object of the invention to provide an apparatus of the character above referred to that fuzes the explosive charge so that said charge is detonated only after predetermined penetration into the material to be excavated.

Generally, it is an object of this invention to provide a reasonably inexpensive and yet practical method and apparatus for the purpose referred to, the apparatus of which is not only small and compact and light in weight, but which is also safe and easily handled with a minimum of effort, and which excavates in a minimum length of time and with predetermined accuracy.

The various objects and features of our invention will be fully understood from the following detailed description of a typical preferred form and application of our invention, throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is a side view with portions broken away to show in section and illustrating the apparatus of the invention in a collapsed condition for ease of handling and for storage. FIG. 2 is a perspective view of the apparatus as it is erected for operation and ready to be fired. FIG. 3 is an enlarged sectional view taken as indicated by line 3-3 on FIG. 2. FIG. 4 is an enlarged detailed sectional view taken as indicated by line 4-4 on FIG. 2. FIG. 5 is an enlarged detailed sectional view of a portion of the structure shown in FIG. 4 and showing elements thereof in different operative positions. FIGS. 6 and 7 are transverse sectional views taken as indicated by

lines

66 and 77 on FIG. 5. FIG. 8 is a perspective view of one of the parts as it appears removed from the structure. FIG. 8a is a view showing operation of certain parts and removed from the surrounding structure. FIGS. 9 to 12 are diagrammatic views illustrating the method and employing of the particular apparatus provided, FIG. 9 showing the apparatus as erected in FIG. 1, FIG. 10 showing the apparatus fired and the explosive means detonated to create a bore. FIG. 11 showing the explosive charge being thrust into the material to be excavated, and FIG. 12 showing the excavation that is formed and created by operation of the method and apparatus.

Explosives have been used in various ways to dislodge materials in order to form openings of various kinds. For example, it is common practive to drill or bore into solid material, such as rock, and to insert an explosive charge therein which fractures and loosens the material when detonated, and in this way a relatively small charge is sufficient. On the contrary, an explosive charge merely applied to the surface of such material has little effect in comparison and requires a relatively large charge in order to accomplish the same result. Therefore, the method and apparatus of the present invention employs a bore into which an explosive charge is inserted to the end that said charge is of minimum size and weight and so that maximum effect is gained therefrom. However, with the method and apparatus as disclosed herein it is not necessary to manually prepare a bore in the material nor to manually insert an explosive charge into such a bore prior to detonation of said charge. With the method and apparatus provided, the steps of boring, in-

3 sertion and detonation are all automatically carried out in the proper sequence and in a positive predetermined manner.

The method provided by the present invention involves, generally, a first step of establishing a bore, a second step of projecting an explosive charge into said bore, and a third step of detonating said charge when it is properly positioned in the bore. Although a preferred form of apparatus is later described for the specific purpose of carrying out the three general steps of this method, it is to be understood that various forms of apparatus may be employed without deviating from the scope of the method involved. That is, each step may be carried out separately, for example, and not necessarily with a particular unitized apparatus wherein the elements combine to operate in combination and jointly, all as later described.

In accordance with the method, the first step of establishing a bore, for instance a bore X (see FIG. in earth formation 10 or the like, is accomplished by means of an explosive shaped-charge, later described. Said shaped-charge is positioned at and faces toward the surface 11 of the earth formation 10 and is preferably spaced a short distance away from said surface 11. When the shaped-charge is detonated, the blast thereof is focused to penetrate through the earth formation 10 a substantial distance creating the bore X which is, in actual practice, a slender elongate opening in the earth formation 10, and in the nature of a pilot hole.

The second and intermediate step of projecting an explosive charge into the bore X (see FIG. 11) may be accomplished by various means and preferably by means of thrust resulting from the ignition of an explosive charge, or rocket type motor. In other words, the explosive charge (later described) is driven into the bore X through ignition of a propellant charge that advances the explosive charge into the bore X for insertion within the earth formation 10 well beneath the surface 11 thereof.

The third and final step of detonating said explosive charge is carried out after said charge has reached a proper detonating position within the earth formation 10 (see FIG. 11). The proper detonating position is indicated at a in FIGS. 11 and 12, in which position the explosive charge is set off to fracture, loosen and remove material from the earth formation 10. As shown, the explosive charge is buried a substantial distance into the earth formation 10 following the direction of the bore X, and as a result, material is blown out of position leaving a spherically shaped cavity Y preferably opening at the surface 11. The cavity Y is defined by a wall 12 and is characterized by radiating interstices 13 caused by fracturing of the earth formation 10 when the explosive charge is detonated.

It will be apparent how explosion of the explosive charge expels material from the earth formation 10 to establish the cavity Y therein. Further, a substantial amount of material will fall back into the cavity Y as indicated at 14. It will be apparent that the effect of the explosion at point a will vary widely depending upon the properties of the particular earth formation involved and upon the condition there-of, but in any case the general result is the same, That is, a cavity Y will be formed, and a certain amount of material 14 will fall back into the cavity or remain therein. In addition to the above mentioned steps, the cavity Y is cleaned out to the depth of the radiating interstices 13, as indicated by the line 15, by manual or any other suitable means, to establish a finished opening, for instance a fox-hole Z for military purposes.

In accordance with the invention there is provided apparatus adapted to be collapsed for handling and transporting and adapted to be erected for operation and use. As best illustrated in FIGS. 1 and 2 of the drawings, the apparatus involves, generally, a boring means A, an explosive charge B, driving means C to project the charge B into the bore X created by the means A, and detonating means D to set off the charge B at a predetermined position in the bore X. In addition, the apparatus includes safety means E for the boring means A, safety means F for the explosive charge B, a standard G, a support H for the boring means A, and igniting means I to initiate operation of the apparatus. Also, there is a housing K to contain the entire structure in a collapsed condition.

The boring means A is provided to carry out the first step of the method and involves a shaped-charge of explosive. The structure of the present invention is constructed along a longitudinal axis that will be referred to as a central vertical axis since the particular apparatus under consideration will ordinarily be employed upon a substantially horizontal surface. The means A is placed to occur on the central axis of the structure and is spaced above the surface 11 when in working position. The means A involves a shell 16 of cylindrical shape closed at its top 17 and open at its bottom. A jet cartridge 18 is carried in the shell 16, said cartridge having a cylindrical outer wall, a flat top wall, and an inverted cone-shaped bottom wall. A linear and retainer 18' is pressed into the shell 16 and has a conical wall conforming to the shape of the bottom wall of the cartridge 18. A jet cartridge booster 20 is carried in the shell 16 adjacent the top of the cartridge 18 to detonate it, as later described. The cartridge 18 is set off by a detonator 19 that is carried and positioned by the safety means E. Further, the axis of the cartridge 18 is angularly related to the central axis of the structure to insure operation of the detonating means D, as later described. For example, it is canted at an angle of about 3 /2.

The explosive charge B is provided to be projected into the bore X in accordance with the second step of the method and involves a high explosive charge. The explosive charge B is placed to occur above the boring means A on the central axis of the structure and is spaced somewhat from the means A. The explosive charge B involves a case 21 of cylindrical shape that carries an explosive load 22. In practice the case 21 is a slender elongate element closed at its upper end 23 and open at its bottom. The load 22 occupies the interior of the case and is confined therein by an exposive booster 24 that is carried in the case at the lower end portion thereof to close the case and to detonate the load 22, as later described. In practice, a thin frangible disc 25 is placed beneath the booster 24 to secure it in the proper position.

The driving means C is provided to project the explosive charge B into the bore X, in accordance with the second step of the method, and preferably involves a rocket type thrust motor. However, it is to be understood that other equivalent thrust producing means may be employed in order to project the explosive charge B downwardly, for example a cylinder and piston mechanism, or the like. The driving means C, as illustrated in the drawings, involves a body 26 of cylindrical shape that carries a propellant charge 27. In practice, the body 26 is a continuation of the case 21 of the explosive charge B and is a slender elongate element closed at its bottom 28 and open at its top. A venturi-shaped nozzle 29 is carried at the top of the body 26 to handle the exhaust blast of the propellant charge 27, when it is ignited, and is a tubular element formed concentric with the central axis of the structure. As best illustrated in FIGS. 1 and 3, the body 26 is slightly larger in diameter than the case 21, there being a downwardly faced shoulder 30 where the two elements are joined.

The detonating means D is provided to set oif the explosive charge B in accordance with the third step of the method and operates to set off the charge B only after said charge has reached a predetermined position in the bore X. It is to be understood that the means D may be varied as circumstances require and may be any suitable mechanism responsive to movement or positioning of the explosive charge B. The particular detonating means illustated in the drawings is in the nature of a fuze and is best illustrated in FIGS. 5, 6 and 7. As shown, the fuze type detonating means D involves a head 31, a firing pin 32, a sear 33 and an actuator 34. The head 31 houses and carries the elements of the detonating means D and also carries the elements of the safety means F for the explosive charge B, later described.

The head 31 is a continuation of the lower end of the case 21 and depends therefrom to carry a pointed tip 31' adapted to have piercing action for purposes later described. The firing pin 32 is seated in the head 31 to face upwardly along the central axis and has a pointed upper end 36 adapted to strike a detonator 37 that is carried and positioned by a shiftable part of the safety means F. A fuze body 35 is shiftably carried within the head 31 to move longitudinally of the head from a normally unactuated position, as shown throughout the drawings, to a position where the detonator 37 strikes the firing pin 32. As clearly shovm in FIG. 5, the fuze body 35 is a cylindrical part that incorporates the means F later described for positioning the detonator 37 and it has a depending stem 35' that is passed through a bore in the lower end portion of the head 31. The stem 35' is tubular in form and accommodates the firing pin 32 so that the pin is slidable within the stem 35. As shown in FIG. 8a the stem 35 is split or bifurcated so that it can be spread laterally by the sear 33, and in accordance with the invention, the bore in the head 31 that passes the stem 35' is provided with an upwardly faced shoulder 35" to have supporting engagement with the stem. As shown, the stem 35 has a fiat end face that spreads diametrically outwardly to seat upon the shoulder 35".

The sear 33 is a shiftable element that operates transversely of the head 31 and firing pin 32, and is is a spool-shaped element with an enlarged central portion 38 and with spaced reduced portions 39 adjacent each end of the portion 38. The sear 33 is round in cross section and extends through an opening that passes transversely through the pin 32 to hold the pin in operating position. When the central portion 38 of the sear is offset as shown in FIG. 4 the enlarged portions of the firing pin 32 engage in the bifurcations of the stem 35' to spread the stem for supporting engagement on the shoulder 35". When the portion 38 is shifted t occur centrally of the structure as shown in FIGS. 5 and 7 the stem 35' is allowed to constrict for release from the shoulder 35" to move longitudinally of the head and downwardly relatively to strike the cap 37 against the firing pin 32.

A feature of the present invention is the actuator 34 provided to release the sear 33 only after said explosive charge B has reached a predetermined position in the bore X. The head 31 is carried at the lower end of the assembly formed by the explosive charge B and driving means C, and the actuator 34 involves a ring-shaped element characterized by a sleeve 40, vanes 41 and by a cam 42. The element forming the actuator 34 is rotatably carried by the head 31, the sleeve 40 being an annular part occupying a correspondingly shaped recess in the head. In practice, the head 31 has a reduced portion forming the recess, and the tip 31 is secured to the said reduced portion, preferably by a threaded connection, to retain the sleeve 40 in working position. Since substantial axial thrust is applied to the sleeve 40 under operating conditions, there is provided a bearing 43, preferably an anti-friction ball bearing unit that rotatably supports the sleeve 40 and which is designed to receive upwardly directed axial forces. As shown, the bearing 43 has an upper race seated in the head 31, a lower race 43 carrying the sleeve 40 and ball bearings intermediate the races.

. One or more vanes 41, preferably a plurality of vanes,

6 for example six vanes, project radially from the periphery of the sleeve in order to engage in the earth formation 10. That is the vanes 41 are adapted to engage with the wall of the bore X as the assembly of parts enters into said bore. As clearly illustrated, the vanes 41 are flat longitudinally disposed fin-shaped parts suitably pitched or inclined in helical planes so as to have a screw action within the earth formation 10. In practice, the vanes are pitched to rotate the sleeve 40 counter clockwise when the actuator 34 is advanced downwardly toward the proper firing position (see FIG. 7).

The cam 42 is of the actuator 34 is a circular cam formed in the inner wall of the sleeve 40 and involves an involutely curved wall (see FIG. 7) that extends circumferentially and which engages one end of the sear 33 to shift the sear to the above-mentioned central position when the sleeve 40 is rotated. A light shear pin 33a assures that the rear 33 remains in a safe position until operation of the actuator 34. The relationship of elements in such that the sear 33 is centrally positioned upon turning of the sleeve 40 caused by the forward and downward movement of the means D and consequent turning of the actuator 34 a predetermined amount, as indicated.

The safety means E is provided to unarm the boring means A, above described, and involves a shiftable carrier 45 to position the detonator 19 that is struck to set off the cartridge 18. In the preferred form-s of the invention the carrier 45 is a slide that operates transversely of the top 17 of the shell 16, said carrier being shiftably supported in an opening 46 that overlies the jet cartridge 18. A leg of the standard G, as later described, normally holds the slide in a safe position, and there is a stop 47 that positions the slide, as shown in FIG. 4, so that the detonator 19 is aligned with the cartridge 18. There is a cotter 48, as shown in FIG. 1, that is engaged in an opening 49 in the slide to normally hold the slide in an unarmed position with the detonator 19 substantially offset from the cartridge 18 and a spring 86 normally yieldingly urges the carrier 45 into engagement with the stop 47. In practice, a central explosive lead filled passage 50 extends between the detonator 19 and jet cartridge 18 when the slide carrier 45 is in the armed position. Further, the top 17 of the shell 16 is provided with a relatively thin wall that normally protects the detonator 19 but which is frangible when struck to set off the said detonator.

The safety means F is provided to unarm the explosive charge B, above described, and involves a shiftable carrier to position the detonator 37 that is struck by the firing pin 32 to set off the booster 24. In the preferred form of the invention the carrier 55 is a rotary element that is unbalanced to operate by means of inertial forces to move the cap 37 into alignment with the firing pin 32 and booster 24 only when the structure is accelerated by the driving means C. As shown, in FIGS. 5 and 8 of the drawings, the carrier 55 is a cylindrical part with an opening 56 extending diametrically therethrough to carry the cap 37. A spring biased weight 57 normally presses against a ratchet tooth at the periphery of the carrier to hold it in the unarmed position, wherein the opening 56 is out of alignment with the central axis of the structure (see FIG. 4). However, the carrier is weighted at 57' (see FIG. 8) so that when the structure is accelerated downwardly and forwardly the carrier is rotated to the position shown in FIGS. 5 and 6 wherein the opening 56 is in alignment with the central axis of the structure. Further, during acceleration the weight 57 is retracted to allow the carrier 55 to turn. In FIG. 8 there is shown suitable spring elements in the form of plates 58 that provide the necessary frictional resistance for ordinary handling shocks, and that provide stops 59 to limit rotation of the carrier and to lock it in the aligned position. When the carrier 55 is in the armed position, the opening communicates with the firing pin 32 through an opening 60 and with the booster 24 through an opening 61. In practice, an intermediate lead charge 62 is carried in the opening 61.

In carrying out the invention, means is provided to assure that the carrier 55 remains in the unarmed position while the apparatus is collapsed and in storage. This means is in the form of a lock pin 65 that is projected through an opening 66 in the head 31 to engage in a notch 67 in the carrier 55, said pin 65 being shown in the process of removal in FIG. 4 of the drawings. When the pin 65 is engaged in the notch 67 the carrier 55 is locked unarmed.

The standard G is provided to support the above described mechanisms in an erected working position such as shown in FIG. 2. The standard G is collapsible and is such as to be easily and quickly manipulated to carry the operative elements of the apparatus. As shown, the standard G involves a collar 70 slidably carried over the body 26 of the driving means C, legs 71 pivoted to the collar 70, and positioning means 72. The collar 70 is a simple tubular element with outwardly projecting ears 73 to carry the legs 71. The legs 71 are secured to the cars 73 by pins 73, there being three legs in the preferred form of the invention. In carrying out the invention, one of the legs has an extension 71' that is used for leveling the apparatus, as circumstances require. The positioning means 72 is best illustrated in FIG. 3 and involves a spring element at each leg and which has an arm 74 anchored to the leg and biased inwardly to engage the body 26 and/or the case 21. The arm 74 normally yieldingly urges the leg 71 outwardly and a rounded terminal end on the arm engages the shoulder 30 to retain the collar 70 in the supporting position. It will be apparent that the collar 70 is operable from the upper end of the body 26 to the upper end of the case 21 (see FIGS. 1 and 2).

The support H is provided to carry the boring means A in operative position relative to the explosive charge B and driving means C and is in the nature of a coupling element that joins the boring means A to the explosive charge B. In practice, the head 31 depends from the case 21 of the charge B and the support H is in the form of a sleeve 75 that surrounds the head 31 and extends forwardly and downwardly over the head to have supporting engagement with the shell 16 of the means A. Suitably spaced screw fasteners, or the like, secure the sleeve 75 to the head 31, preferably spaced therefrom leaving an annular gap between the head and sleeve. The said screw fasteners are shear elements designed to fail at a predetermined load or pressure. Similarly, ordinary screw fasteners secure the top 17 of the shell 16 to the sleeve leaving some distance between the vertex of the tip 35 and the frangible wall that protects the cap 19.

The igniting means I is provided to set off the apparatus of the present invention and forms a closure that protects the propellant charge 27 of the driving means C. Any suitable device may be employed for ignition of the proconventional igniting means involving a closure 76, a safety fuse 77, and an operator 78. The closure 76 normally occupies the nozzle 29 and contains an igniting charge 79 adapted to ignite the charge 27 whereby pressure acts to discharge the closure 76 from the nozzle 29. The operator 78 is manually actuated by withdrawing a cotter pin therefrom (see FIG. 2) to activate the safety fuse and the charge 79. In any case, a time interval is established by the operator 78 between the moment of manual actuation and the moment of detonation, during which time interval a person can remove himself to a safe distance.

The housing K is provided to contain and store the collapsed apparatus in an unarmed and safe condition. The housing K is a closed tube 80 having a cover 81, and of a diameter to slidably receive the legs 71 that are spaced to centrally position the means A, charge B and means C. With the legs 71 collapsed, the lock pin 65 remains engaged with the carrier 55 to unarm the explosive charge B, and the cotter 48 remains engaged in the opening 49 to secure the slide carrier 45 to unarm the shapedcharge of the means A. In accordance with the safety features of the present invention, a lanyard extends from the operator 78 to the cotter 48 so that by ordinary manipulation of the operator the cotter 48 is removed from the carrier 45. As above mentioned, the lock pin 65 is normally engaged with the carrier 55 and it is retracted to pre-arm the charge B only when the leg 71 carrying the pin 65 is moved to an erecting position. Thus, the apparatus is automatically pre-armed as it is erected as shown in FIG. 2.

With the apparatus erected as thus far described, operation is initiated by manual actuation of the igniting means I that times the ignition of the propellant charge 27 of the driving means C. Upon ignition of the charge 79 the propellant charge 27 acts to discharge gases through the nozzle 29 to create thrust for moving the elements of the apparatus downwardly and forwardly. In practice, the initial thrust is substantial and sudden with the result that the charge B and detonating means D, and associated elements, are accelerated rapidly. In accordance with the invention, the shear screws at the sleeve 75 of the support H are structurally weak and fail in order to allow the tip 31' to be guided by the sleeve 75 to advance into engagement with the detonator 19 to set off and detonate the shaped-charge of means A, the inertia of the elements of means A being sufficient to hold said means in position, momentarily.

With the detonation of the boring means A the bore X is formed in the earth formation 10 and on an axis canted relative to the central axis of the apparatus. The elements of the means A and H are fabricated of frangible materials that disintegrate from the forces of the blast of means A and whereby there is no obstruction in the downward path of the explosive charge B. With the combustion of the propellant charge 27 well under way the driving means C and charge B are moved with accelerated force into the bore X established ahead thereof whereupon the vanes 41 operate in the earth formation, which action is assured by canting the bore X, to rotate the sleeve 40 to release the fuse body 35, all as above described. As the charge B and safety means F are accelerated the carrier 55 is rotated by inertial forces as above described so that the charge B is armed for detonation when the proper firing position is reached beyond the surface 11 and well within the earth formation 10. Upon reaching the lower end portion of the bore X, the moving structure is decelerated rapidly by means of frictional engagement with the earth formation 10. Thus the fuze body 35 carries the detonator 37 forcefully into engagement with the firing pin 32, all to the end that the explosive charge B is set off at the point a, as set forth above.

Having described only a typical preferred form and application of our-invention, we do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to ourselves any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims:

Having described our invention, we claim:

1. An apparatus for excavating material and including:

(a) a standard disposed on an axis normal to and for supporting engagement upon the surface of the material to be excavated,

(b) a shaped-charge of explosive supported by the standard on said axis to form a bore in said material and having a detonator to be set off by percussion,

(c) a safety means comprising a carrier shiftably supporting the detonator to move it from an unarmed offset position to an armed position aligned with said ax1s,

(d) a second explosive charge releasably carried by the standard on said axis and having a head movable into engagement with the detonator of the shapedcharge to detonate it,

(e) a rocket propellant charge to thrust said explosive charge into the detonator of the shaped-charge and into the bore,

(f) and means to detonate said second explosive charge and comprising a fuse carrying body, a sear normally engaging said fuse carrying body and a rotatable actuator adapted to release the sear from the fuse carrying body, said actuator having at least one radially projecting element engageable with the side walls of the bore to rotate the actuator and detonate the fuse, whereby said second charge is set off at a predetermined depth within said bore and said material is loosened forming a cavity.

2. An apparatus for excavating material and including:

(b) a shaped explosive charge carried by said standard to form a bore in said material,

(c) a second explosive charge carried by the standard on said axis,

(d) a rocket to thrust said second explosive charge into the bore,

(e) and means to detonate said second explosive charge and comprising a fuse carrying body shiftable longitudinally, a sear normally engaging said fuse carrying body and a rotatable actuator with a cam face to release the sear from the fuse carrying body, said actuator having radial vanes engageable with the side walls of the bore and pitched to rotate the actuator and detonate the fuse, whereby said second explosive charge is set off at a predetermined depth within said bore and said material is loosened and expelled forming a cavity.

3. Apparatus according to claim 2 wherein said shaped charge is slightly tilted with respect to said axis to ensure engagement of said radial vanes with the side walls of the bore.

4. An apparatus for excavating material including:

(a) a support disposed on a longitudinal axis normal to the material to be excavated and carrying a shapedcharge of explosive to form an elongated bore in said material and along said axis;

(b) a container having a second explosive charge positioned therein, said container and said second explosive charge being substantially aligned with said longitudinally disposed axis and with said shaped-charge;

(c) driving means coupled to said second explosive charge for projecting said second explosive charge along said longitudinal axis and into said bore; and

(d) detonating means mounted on the exterior surface of the side wall of said container and engageable with the side walls of said bore to detonate said second explosive charge at a predetermined depth within said bore, whereby said material is loosened and expelled, forming a cavity.

5. Apparatus according to claim 4 wherein said detonating means mounted on the exterior of the container includes an actuator rotatable on said longitudinally disposed axis and having vanes engageable with the side walls of said bore.

6. Apparatus according to claim 4 wherein said first mentioned shaped-charge of explosive is slightly tilted with respect to said longitudinally disposed axis.

References Cited by the Examiner UNITED STATES PATENTS 1,661,091 2/28 Riabouchinski 891.7 2,408,419 10/46 Foster 89--l.02 2,601,522 6/52 Heiland et al. 102-22 X 2,757,611 8/56 Church et al.

2,946,283 7/60 Udry 89-1.02 X

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL BOYD, SAMUEL W. ENGLE, Examiners.

Claims

1. AN APPARATUS FOR EXCAVATING MATERIAL AND INCLUDING: (A) A STANDARD DISPOSED ON AN AXIS NORMAL TO AND FOR SUPPORTING ENGAGEMENT UPON THE SURFACE OF THE MATERIAL TO BE EXCAVATED, (B) A SHAPED-CHARGE OF EXPLOSIVE SUPPORTED BY THE STANDARD ON SAID AXIS TO FORM A BORE IN SAID MATERIAL AND HAVING A DETONATOR TO BE SET OFF BY PRECUSSION, (C) A SAFETY MEANS COMPRISING A CARRIER SHIFTABLY SUPPORTING THE DETONATOR TO MOVE IT FROM AN UNARMED OFFSET POSITION TO AN ARMED POSITION ALIGNED WITH SAID AXIS, (D) A SECOND EXPLOSIVE CHARGE RELEASABLY CARRIED BY THE STANDARD ON SAID AXIS AND HAVING A HEAD MOVABLE INTO ENGAGEMENT WITH THE DETONATOR OF THE SHAPEDCHARGE TO DETONATE IT, (E) A ROCKET PROPELLANT CHARGE TO THRUST SAID EXPLOSIVE CHARGE INTO THE DETONATOR OF THE SHAPED-CHARGE AND INTO THE BORE, (F) AND MEANS TO DETONATE SAID SECOND EXPLOSIVE CHARGE AND COMPRISING A FUSE CARRYING BODY, A SEAR NORMALLY ENGAGING SAID FUSE CARRYING BODY, A SEAR NORMALLY TUATOR ADAPTED TO RELEASE THE SEAR FROM THE FUSE CARRYING BODY, SAID ACTUATOR HAVING AT LEAST ONE RADIALLY PROJECTING ELEMENT ENGAGEABLE WITH THE SIDE WALLS OF THE BORE TO ROTATE THE ACTUATOR AND DETONATE THE FUSE, WHEREBY SAID SECOND CHARGE IS SET OFF AT A PREDETERMINED DEPTH WITHIN SAID BORE AND SAID MATERIAL IS LOOSENED FORMING A CAVITY.