US3517469A - Camouflet device - Google Patents

Description

June 30, 1970 C. H. BROWN CAMOUFLET DEVICE Z Sheets-Sheet 1 Filed Sept. 27. 1968 INVENTOR CLAUDE H. BROWN BY b a/M, Swamp wedca 7 Hat/u:

ATTORNE f3 June 30, 1970 c. H.-BROWN CAMOUFLET DEVICE 2 Sheets-Sheet 2 Filed Sept. 2'7. 1968 United States Patent O 3,517,469 CAMOUFLET DEVICE Claude H. Brown, Arlington, Tex., assignor to Jet Research Center, Inc., Arlington, Tex., a corporation of Texas Filed Sept. 27, 1968, Ser. No. 763,059 Int. Cl. E02d 5/80 US. Cl. 52-155 4 Claims ABSTRACT OF THE DISCLOSURE A camouflet device which is adaptedto haveapplied thereto an initial accelerating force for propelling the device downwardly into the ground. The camouflet device in cludes a body, containing an inertial member mounted for free movement between vertically spaced upper and lower positions. A detonator is carried by the inertial member. Detonating means is mounted within the body for movement between safety and firing positions of the detonating means. In the firing position the detonating means is positioned to be struck by the detonator when the inertial member moves to the lower position, to thereby detonate the detonator. In the safety position, the detonating means is spaced out of contact with the detonator. Passage means in the body admits earth into the body upon contact with the ground to force the detonating means from the safety to the firing position.

BACKGROUND OF THE INVENTION This invention relates to a camouflet device for an explosive earth anchor. The camouflet is intended to explosively expand the lower end of the anchor after it has been propelled into the ground. In particular, the invention relates to a camouflet device suitable for use with a pipe line stake.

In securing an object to an immersed earth surface, such as the sea bed, it is sometimes advantageous to utilize an explosively actuated earth anchor. One recent use for an earth anchor has been for the purpose of securing oil or gas pipe lines to the sea bed.

Typically, an earth anchor may include a slender elongate stake propelled downwardly out of a housing by explosion of a first explosive charge. A second or camouflet charge in the head of the stake is detonated once the stake has been driven into the ground to expand the head of the stake below ground level to secure it in the earth.

With such an arrangement, it is particularly important to insure that the camouflet charge does not fire prematurely while the stake is still moving into the ground, before the lower end of the stake has reached its desired below ground location. It is also important that the camouflet charge should be in a safe condition while the stake is being handled by personnel prior to installation.

For this reason, some prior earth anchors have included various forms of delay train to the camouflet charge to fire a predetermined time interval after initiation of the first or propelling charge. However, with a system of this type, operating on the basis of a predetermined time delay, there may be problems in correlating the time delay in seconds with the desired penetration of the lower end in feet. This may arise because the necessary time-distance relationship is hard to ascertain, particularly when operating in submerged strata varying from soft mud to rock. It would therefore be desirable to provide an arming system for the camouflet charge which functioned in response to the motion characteristics of the stake through the strata so that the camouflet charge did not explode prematurely.

One prior arming system for this purpose includes an 3,517,469 Patented June 30, 1970 "Ice inertial member carrying a detonator for the camouflet charge. During initial downward acceleration of the stake into the ground, inertia forces hold the inertial member in an upper position within the stake. However, as the device decelerates to rest, the inertial member carries the detonator down to a lower position under gravity to impinge onto a detonating pin to cause detonation. Initially, the detonating pin is located in a safety position within the stake, spaced out of contact with the lower position occupied by the detonator so that accidental firing of the unit cannot occur. However, on entry of the device into the ground the detonating pin is advanced into a firing position in which it may be struck by the detonator when it moves to its lower position. Movement of the detonating pin to the firing position is effected by an arming mechanism including an earth-engaging propeller which is rotated upon downward movement through the earth to permit the detonating pin to be moved to the firing position.

Although this prior device may be satisfactory for some purposes, the construction of the earth-engaging propeller and associated rotary structure renders the tool complex and costly. In addition, a particularly serious problem may arise if the ground to be penetrated is particularly hard as the relatively vulnerable, propeller-like arming device may be ripped off during passage of the tool into the ground before the detonating pin has been moved to its firing position. In this event, the camouflet charge may never be detonated with the result that the stake may be inadequately secured to the ground.

OBJECTS AND SUMMARY OF INVENTION It is therefore a general object of the invention to provide a camouflet device which obviates or minimizes problems of the type previously noted.

It is a particular object of the invention to provide a camouflet device capable of unimpaired operation even under circumstances when the device is to he propelled into ground of unusually hard characteristics.

It is another object of the invention to provide a camoufiet device of the type generally described, which is of a particularly simple and low cost construction.

A camouflet device according to a preferred embodiment of the invention is intended to accomplish at least some of the foregoing objects. The camouflet device is adapted to have applied thereto an initial accelerating force for propelling the device downwardly into the earth. The device includes a longitudinally extending body which is adapted to be disposed vertically during downward movement. An inertial member is mounted for free longitudinal motion within the body and occupies a lower position when under the influence of gravity alone. Dur ing downward acceleration of the body into the ground, the inertial member lags behind the body to occupy an upper position within the body spaced above the lower position. A detonator is connected with and carried by the inertial member. Detonating means is provided for detonating the detonator upon impact therewith. The detonating means is mounted in the body for movement between safety and firing positions. The detonating means, in the firing position, is positioned to be struck by the detonator when the inertial member moves to the lower position thereof. The detonating means, in the safety position thereof, is spaced out of contact with the detonator in all positions thereof. Passage means in the body is adapted to direct earth inwardly of the body on impact of the body with the ground. The earth entering the passage means contacts the detonating means to move it to the firing position.

By this construction, it will be appreciated that detonation of the detonator is prevented while the device is still accelerating downwardly through the earth strata,

thereby avoiding premature detonation of the camouflet device.

In addition, safety of personnel is enhanced by initially positioning the detonating means so that it is spaced out of any possible contact with the detonator prior to entry of the device into the ground.

Also significant is the manner in which the ground surface is utilized directly to effect arming of the detonating means, by causing the earth entering the passage means to function as a piston to move the detonating means to the firing position.

THE DRAWINGS A camouflet device according to a preferred embodiment of the invention is illustrated in the accompanying drawings inwhichL. W a

FIG. 1 is a perspective view of a pipe line stake with which a camouflet device constructed in accordance with a preferred embodiment of the invention, is particularly suitable for use;

FIG. 2 is a perspective view of a portion of the pipe line stake shown in FIG. 1 with a lower portion of the pipe line stake shown expanded by detonation of the camouflet device;

FIG. 3 is a perspective view partially in section of the camouflet device according to the preferred embodiment of the invention;

FIG. 4 is a cross-sectional side view of the camouflet device shown in FIG. 3, with the parts of the device shown in the relative positions they initially occupy prior to use of the device;

FIG. 5 is a cross-sectional side view similar to that of FIG. 4 but with the parts of the device shown in the positions they occupy during initial downward acceleration of the device into the ground,

FIG. 6 is a cross-sectional side view generally similar to that of FIG. 5 but with the parts of the device shown in the positions that they occupy upon initial contact of the device with the ground during continued downward acceleration of the device; and

FIG. 7 is a crosssectional side view generally corresponding to that of FIG. 6 but with the parts of the device shown in the positions they occupy in a subsequent stage in which downward acceleration of the device has substantially ceased.

DETAILED DESCRIPTION Referring to FIG. 1 of the drawings, a pipe line stake assembly of the type with which a camouflet device according to the present invention, is particularly suitable for use, is there shown. The pipe line stake assembly includes a fiat horizontal clamp 2 engaging and embracing the upper surface of a pipe line 4. Secured to the upper side of the clamp 2 is a vertical tube 6, having releasably bolted thereto a firing assembly 8.

The firing asembly comprises a guide tube 10, concentric and communicating with the tube 6, and having a closed upper end 12. Positioned within the guide tube 10 is a slender elongate pipe line stake 14 having an enlarged, piston-like upper end 16. A pointed lower end of the pipe line stake 14 is slidably and snugly received within a deformable crush tube 18 extending concentrically and vertically downwardly.

A propelling charge positioned within the guide tube 10, between the closed upper end 12 thereof and the piston 16 is exploded to drive the elongate stake 14 downwardly into the underlying sea bed. A reaction plate 21, carried by barrel 10 reacts with the adjoining water to offset recoil force acting on this barrel. As the pipe line stake 14 is forced downwardly, the upper piston end 16 enters and expands the crush tube 18 which decelerates the stake so that it does not pass downwardly through and out of the clamp 2.

Finally, a second or camouflet charge 22 at the lower end of the stake 14 is exploded (FIG. 2) to deform the lower line stake portions 14(a) radially outwardly into 4 the surrounding earth to secure the stake against release from the earth.

Of particular interest in the context of the present invention, is the camouflet device utilized to expand the lower end of the pipe line stake below the surface of the ground. Although this camouflet device is described with reference to a pipe line stake arrangement of the type outlined above, it will be appreciated that it is not limited to this particular application and may in fact be utilized in many other forms of ground engaging tool.

Moreover, it is not necessary that the tool with which the camouflet device is utilized must be explosively propelled into the ground. Other methods of providing a downward acceleration to the tool, to cause it to enter the ground, may be utilized. For example, such methods may include the use of resilient spring-type or compressed fluids such' as steam or air.

Referring to FIG. 3, the lower end of the pipe line stake 14 may be seen to include a camouflet device 24 constructed in accordance with the preferred embodiment of the invention.

The camouflet device 24 includes a hollow' cylindrical outer housing 14 (a) integral with and forming the lower end portion of the pipe line stake 14. Threadedly received within the lower end of the pipe line stake 14 is a pointed, generally conical nose body 26 formed in two portions, namely, a forward nose body 26a and a main nose body 26b.

The main nose body 26b includes a solid, axially and outwardly extending circular boss 28. Boss 28 is externally threaded about its periphery to engage an internally, threaded portion at the lower end of the pipe line stake 14. Tool receiving openings 30 are provided in the periphery of the main body 26b to enable insertion of a suitable tool for tightening up the main nose body in threaded engagement to the pipe line stake.

An upper, radial flat face 32 of the main nose body 26b is provided with a central, circular, downwardly extending recess 34. The recess 34 is defined by a flat, circular radial face 36 which is parallel to, and spaced below, the face 32 and by a peripherally and axially extending, cylindrical edge Wall 38.

The function of the recess 34 is to receive the lower end of an explosive container 40. This container 40 comprises an upwardly extending circular metal tube. The upper end of the explosive container 40 is sleeved over a circular wooden boss 42 which is integral with, and projects downwardly from, a disc-like wooden retainer plate 44. The wooden retainer plate is connected with the nose body by a plurality of threaded retainer rods 46 which are disposed in cage-like configuration about, and spaced from, the explosive container 40.

One end of each container rod 46 is threadedly engaged with the main nose body 26b, while the upper end of each retainer rod extends through the wooden retainer plate 44 and is provided with a nut 48 bearing against the retainer plate. The nuts 48 of the various retainer rods may be tightened up to cause the retainer plate to bear down on the explosive retainer so that it is located firmly against the nose body, with its lower end extending into and received in the recess 34.

Porous filler material 50 is provided about the exterior of the explosive container 40. This material 50 extends between the upper face 32 of the main nose body 26b and lower face of the wooden retainer 44. Additional filler material 52, in the form of a disc coextensive with the retainer 44, is provided on the upper surface thereof.

A camouflet charge of explosive 54 is packed within the interior of the explosive container 40, between the face 36 of the nose body and the lower face of the boss 42 of the retainer. The amount of explosive is sufficient to cause the body portion 14(a) to be blasted outwardly into strips, upon detonation of the explosive, with the strips being curled out in the configuration generally disclosed in FIG. 2.

Also provided within the main nose body 26b is an axially extending arming chamber 56. The arming chamber 56' has its upper end 58 spaced below the surface 36 which defines the recess for the explosive container at the upper side of the main body. The vertically spaced, radially extending wall surfaces 36 and 58 define an internal wall 60 ofthe main nose body 26b. A central opening 62 in the internal wall 60 snugly receives an explosion initiator housing 64.

The initiator housing 64 comprises a metal tube having an open lower end which extends into the arming chamber 56 adjacent the end wall 58. The housing 64 extends vertically almost the entire length of the explosive container 40 and has a closed upper end spaced below the boss 42 and the retainer 44. A plurality of vertically spaced openings 66 in the initiator housing 64 place the interior of the initiator housing in communication with the remaining portions of the interior of the explosive container which are packed with the explosive 54. A retaining collar 68, pressed about the exterior of the initiator housing 64 in abutting contact with the surface 36, locates the initiator housing 64 in fixed relation to the main nose body 26b and the explosive container 40.

The initiator housing 64 receives a concentric, axially extending length of detonating cord 70. The length of detonating cord, which in the preferred embodiment is of the type known commercially as primer cord has its external surfaces spaced from the adjacent internal surfaces of the initiator housing 64 and is movable upwardly and inwardly within the initiator housing through the open lower end thereof. In the preferred embodiment, the length of detonating cord 70 has a burning time of approximately two seconds to constitute a delay train, although it will be appreciated that by suitable variation of dimensions, this burning time can be adjusted as required.

At its lower end, the detonating cord 70 is connected to a commercially available detonating cap or initiator 72. The initiator 72, in turn, is connected with the forward end of a conventional blank cartridge 74. Upon detonation of the cartridge 74 (in a manner to be described), the initiator 72 causes the lower end of the detonating cord 70 to be ignited. The burning continues along the detonating cord in a conventional manner until, at the conclusion of the previously mentioned period of burning, the ignition is transmitted to the openings at the upper end of the initiator housing 64 to cause explosion of the camouflet charge within the container 40.

The cartridge 74, which is a conventional .22 calibre blank cartridge, and the initiator 72 are carried by an inertial member 76.

The inertial member 76 comprises a solid metal cylinder mounted for free sliding motion within and along the arming chamber 56. The member 76 is provided with a cartridge receiving, lower central bore 78 into which the cartridge 74 is pushed, with the head of the cartridge remaining outside the inertial member at the lower end thereof. The dimension of the bore 78 is such that there is sufficient friction or interference fit, once the cartridge 74 has been inserted, to retain it in position. At the upper end of the cartridge receiving bore 78 is another bore 80 extending vertically through to the upper side of the inertial member to receive the initiator 72 and the lower end of the detonating cord 70.

At the lower end of the arming bore 46, there is provided a relatively enlarged, internally threaded bore 82. Bore 82 is threadedly engaged by a correspondingly configured, externally threaded male boss 84 which is positioned on the upper side of the forward nose body 26a. The boss 84 includes an upper, fiat radial surface 86 which constitutes a shoulder at the lower end of the arming bore. The inertial member 76 rests on surface 86 in a lower or safety position of this inertial member.

Tool receiving openings 88 are provided in the forward peripheral surface of the forward body 26a to enable it 6 to be tightened in threading engagement with the main body 2612.

Extending centrally and entirely through the forward nose body 26a, is an internal passage 90. The passage 90 includes a lower portion 90a open at its lower end and an upper portion 90b, extending upwardly from the lower portion 90a. At the junction of the portions 90a and 90b of the internal passage, there is a radially extending shoulder 92.

Mounted in the enlarged or upper bore portion 90b of the passage 90 is a firing member 94.

Firing member 94 has a cylindrical, disc-like base 96 slidably and snugly abutting the interior of the enlarged upper bore 9012. Initially, on assembly, the disc-like base 96 rests against the shoulder 92 in abutting contact therewith. Extending upwardly from the disc 96, and integral therewith, is a central cylindrical body 98. Body 98 is concentric with and spaced radially inwardly from the upper bore 9012. At its forward end, the central body 98 has an integral, forwardly extending forward body 100 of relatively reduced diameter. On the forward radial end of the forward body 100, there is positioned a pointed firing pin 102. Pin 102 is aligned axially with a detonating cap 104 in the head of the previously mentioned cartridge 7 4.

With the disc 96 in the lower or safety position, abutting the shoulder 92, the firing pin 102 is spaced below the shoulder 86 by a sufiicient distance to insure that the detonating cap 74 is spaced out of contact with the firing pin 102. As an additional safety precaution, a reduced annular insert 106 is threadedly engaged in the upper end of the enlarged bore 90]; so that if the cartridge 74 should accidentally fall out of the carrier 76, it would rest on the upper edge of the insert 106 with the detonating cap 104 still being spaced above the firing pin 102 to avoid accidental detonation.

To retain the firing device 94 in the lower or safety position against accidental displacement therefrom, a detent in the form of an annular ring of frangible cement 110 is positioned in contact with the forward surface of the disc-like base 96. However, on impact of the stake with the ground (as will be described in more detail) earth entering the lower bore portion 90a of the passage 90 forces the firing device 94 upwardly with sufficient force to brake the cement detent 110 so that the firing device 94 may move upwardly in the forward nose body 26a. Upward motion of the firing device is eventually limited by contact of the central body 94 with the lower surface of the insert 106. At this time, the firing device is positioned in a firing position at which the firing pin 102 is spaced vertically above the shoulder 86 so that it may be impinged upon by the detonator cap 104 of the cartridge 74.

OPERATION Operation of the device follows a sequence of stages illustrated in FIGS. 4-7.

An initial step is to explode the propelling charge 20 (FIG. 1) to propel the stake 14 downwardly into the sea bed. The effects of the explosion of the propelling charge 20 are isolated from the camouflet charge 54 by the filler material 50 and 52 surrounding the camouflet charge. Upon initial downward acceleration of the stake 14, inertia causes the inertial member to lag relatively behind the motion of the stake with the result that the inertial member 76 occupies an upper position (FIG. 5) within the arming chamber 56. In this upper portion, the lower surface of the arming member 76 is spaced an appreciable distance above the surface of the shoulder 86. At this time, the firing device 94 still occupies its lower safety position in which the firing pin 102 is spaced out of possible contact with any part of the cartridge.

As the stake continues its downward and still accelerating movement, the lower end of the forward nose body 26a commences to enter the ground (FIG. 6). As this occurs, earth is forced upwardly into the lower bore portion 90a of the passage 90. This earth acts like a piston upon the lower surface of the base 96 of the firing device, with suificient, upwardly directed force to shear the cement detent 110.

Continued downward motion of the pipe line stake causes earth to be driven upwardly through the passage 90 until the firing device 94- has been moved upwardly to its firing position, with the firing pin 102 projecting above the shoulder 86. At this time, however, as downward acceleration is continuing, the interial member 76 is still spaced sufficiently above the shoulder 86 to hold the cartridge 74 out of contact with the firing pin 102.

Downward motion of the pipe line stake continues, subject to the decelerating forces provided by earth resistance and by the action of the previously mentioned crush tube 18 (FIG. 1). Eventually, the rate of deceleration, plus the effect of gravity, exceeds the previous acceleration. At this time, the inertial member 76 commences to fall downwardly within the arming bore 56. This downward motion carries the detonating cap 104 of the cartridge onto the now exposed firing pin 102 with sufficient force for the cartridge 74 to be detonated. Detonation of the cartridge 74 causes the initiator 72 to ignite the detonating cord 70. This cord 70 continues to burn for the predetermined delay period which is sufficient for any remaining downward motion of the pipe line stake to be stopped by the decelerating forces previously described. Thus, at the conclusion of the predetermined period, the pipe line stake has come to rest. Thereupon, the explosive camouflet charge 54 explodes to splay the adjacent portions of the pipe line stake 14 outwardly, thus insuring that the stake is properly secured at its lower end to the earth.

SUMMARY OF ADVANTAGES It will be appreciated that in providing a camouflet device according to the present invention, certain significant advantages are provided.

In particular, the provision of a firing device which is held out of all possible contact with the detonator prior to entry of the stake into the ground, offers important advantages. For example, this construction insures that the camouflet charge will not fire prematurely before the lower end of the stake has reached its desired belowground penetration level. In addition, the possibility that accidents might occur due to inadvertent dropping of the pipe line stake by personnel prior to use of the stake is also minimized.

The construction whereby the firing device is moved from the safety to the firing position is also of particular significance. By utlizing a simple earth passage, earth is directly forced into the body and is utilized to arm the firing device. This construction is particularly simple and low in cost. In addition, this arrangement is not subject to breakage or damage problems when the pipe line stake is being utilized on unusually hard packed earth.

In describing the invention, reference has been made to a preferred embodiment. However, those familiar with this disclosure and skilled in the pipe line staking art may envision additions, deletions, substitutions, or other modifications which would fall within the purview of the invention.

I claim:

1. A camouflet device adapted to have applied thereto an initial accelerating force for propelling the device downwardly into the ground, the camouflet device comprising:

a longitudinally extending body adapted to be generally vertically disposed during downward motion,

an inertial member mounted for free motion within said body, said inertial member occupying a lower position thereof within said body under the influence of gravity alone, said inertial member during downward acceleration of said body into the ground lagging behind the motion of said body to occupy an upper position therein spaced above said lower posiition, a detonator connected with and carried by said inertial member, detonating means mounted in said body for detonating said detonator upon impact therewith, said detonating means in a firing position thereof within said body positioned to be struck by said detonator when said inertial member moves to the lower position thereof, said detonating means in a safety postion thereof within said body being spaced out of contact with said detonator in all positions thereof, restraining means, fixed with respect to said body, for

preventing movement of said inertial member towards said detonating means beyond said lower position of said inertial member, yieldable retaining means, normally fixed with respect to said body, for normally and positively maintaining said detonating means in said safety position within said body and spaced out of contact with said detonator in all positions thereof; and, passage means in said body providing communication between said detonating means and the lower end of said longitudinally extending body adapted to be generally vertically disposed during downward motion, said passage means upon impact with the ground causing earth to enter said body to contact said detonating means to move said detoning means, with respect to said body, to said firing position thereof against the restraining force provided by said yieldable retaining means. 2. A camouflet device as defined in claim 1 further including:

an explosive charge positioned within said body, said explosive charge being exploded by said detonator upon detonation thereof to cause outward deformation of adjacent portions of said body. 3. A camouflet device as defined in claim 1 wherein said yieldable retaining means comprises:

shearable retaining means for initially retaining said body and said detonating means in fixed relation in said safety position, said detonating means being contacted with sufiicient force by the earth entering said passage means to shear said retaining means, said detonating means thereafter being moved by the earth entering said passage means to said firing position. 4. a camouflet device as defined in claim 2 further including:

time delay means interposed between said detonator and said explosive charge for delaying explosion of such charge until a predetermined delay period after detonation of said detonator.

References Cited UNITED STATES PATENTS 3,222,842 12/1965 Luedloff et a1 52155 X 3,233,415 2/1966 Thomas 52-155 FOREIGN PATENTS 352,215 7/1931 Great Britain.

ALFRED C. PERHAM, Primary Examiner US. 01. X.R.

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