US 3707917 A
A device for funneling a detonation wave from a detonator to a main explosive charge to substantially eliminate the detrimental effects of axial misalignment of the detonator and main explosive charge, comprising a detonation-confining body carrying therein a generally I-shaped explosive extending axially through it. The device is placed between a detonator and main charge and in axial alignment with the latter. A detonation wave from the detonator may be eccentrically received by one end of the I-shaped explosive, but it is funnelled down the column of the I, which is in axial alignment with the main charge, so that the latter "sees" an axially-aligned detonation wave emanating from the other end of the I. The explosive, the material forming the detonation-confining body and the dimensions of the I-shaped charge are selected to insure that there is substantially no interference with the detonation of the I-shaped explosive, to preferably maximize the detonation velocity through the explosive, and to ensure that detonation of the main explosive is initiated from the I-shaped explosive and not from the confining body.
Description (OCR text may contain errors)
States Zernow et al.
atent 91  PRECISION INITIATION COUPLER  Inventors: Louis Zernow, Glendora, Arthur Louis Mottet, Pacific Palisades, both of Calif.
 Assignee: Whittaker Corporation  Filed: Dec. 23, 1970  Appl. No.: 91,664
Primary Examiner -verlin R. Pendegrass Att0rney-D0nald E. Nist and Jay l-l. Quartz  ABSTRACT A device for funneling a detonation wave from a detonator to a main explosive charge to substantially eliminate the detrimental effects of axial misalignment of the detonator and main explosive charge, comprising a detonation-confining body carrying therein a generally l-shaped explosive extending axially through it. The device is placed between a detonator and main charge and in axial alignment with the latter. A detonation wave from the detonator may be eccentrically received by one end of the I-shaped explosive, but it is funnelled down the column of the l, which is in axial alignment with the main charge, so that the latter sees" an axially-aligned detonation wave emanating from the other end of the l. The explosive, the material forming the detonation-confining body and the dimensions of the I-shaped charge are selected to insure that there is substantially no interference with the detonation of the l-shaped explosive, to preferably maximize the detonation velocity through the explosive, and to ensure that detonation of the main explosive is initiated from the I-shaped explosive and not from the confining body.
10 Claims, 3 Drawing Figures PATENIEDJM 2 I975 6 my M mo J M Z0 L 9 PRECISION INITIATION COUPLER BACKGROUND OF THE INVENTION This invention relates to explosive charges and, more particularly, to explosive devices in which a detonator is used to initiate detonation of a main charge.
Manufacturing tolerances in the metal parts of fuzing systems used in shaped charge ammunition, as well as the variations in the symmetry of the output of fuze detonators, often results in a net eccentricity of the point of initiation of the shaped charge relative to its axis. For precision shaped charge assemblies, this eccentricity of the initiation can result in significant degradation of the shaped charge performance. For example, losses up to 25. perce ntand more may result from an eccentricity of initiation on the order of 0.150 inches.
SUMMARY OF THE INVENTION This invention is embodied in a precision initiation coupler which is designed to be placed between a detonator and a main charge to correct any misalignment of the axes of the detonator and main charge which could reduce the effectiveness of the output of the main charge. This invention can be employed with any combination of explosive charges where the effectiveness of the combination of charges is dependent on alignment of the axes of the charges making up the combination. However, this invention, at present, has particular utility when employed with shaped charge ammunition.
In brief, the invention comprises a detonation-confining body having an I-shaped cavity formed therein and extending through the confining body. The cavity is axially aligned with the axis of the confining body and is filled with an explosive to provide an explosive charge with an I-shaped configuration. The precision initiation coupler is axially aligned with the main charge and, when in this position, is not axially aligned with a misaligned detonator. However, the particular 1- configuration of the explosive in the coupler is such that the eccentric detonation wave from the detonator is received and transmitted by one end of the I-shaped charge through the web or column section of the I which is axially aligned with the main charge. The detonation wave is thus axially transmitted through the other end of the I-shaped charge and this, in turn, produces axially aligned detonation of the main charge.
The advantage of employing the precision initiation coupler of this invention is that it can substantially eliminate the effect of misalignments between detonators and main charges which the former are employed to detonate. For example, it can reduce detonator input eccentricities to the coupler as large as 0.150 inches to coupler outputs having a residual eccentricity of 0.01 inches and less. This alignment correction is accompanied by a substantial increase in main charge effectiveness and this increase in effectiveness may be as much as 30 percent or more depending upon the particular application. Use of the herein-described coupler also eliminates the necessity of employing close tolerances in fuzing systems thereby reducing the cost of such systems normally associated with the maintenance of close tolerances. These advantages are obtained with a coupler which is of simple design and which can be readily and inexpensively assembled.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the precision initiation coupler of this invention.
FIG. 2 is an elevational sectional view of the coupler of FIG. 1 taken along the line 2-2 of FIG. 1.
FIG. 3 is an elevational sectional view of a simplified shaped charge system illustrating the use of the hereindescribed coupler in combination with a fuze body and a shaped charge.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2, the numeral 10 designates a precision initiation coupler of this invention. The coupler 10 comprises a normally cylindrical body 12 which is provided with an axially aligned cavity 14. The cavity 14 has a generally I-shaped configuration. As shown in FIGS. 1 and 2, the cavity 14 is symmetrical about its transverse axis. However, it need not be as will be further described hereafter.
The terms upper and lower are used herein for simplicity of description and otherwise have no significance since the coupler 10 does not have to be used in an axially vertical position.
The cavity 14 comprises a pair of expanded-diameter, normally-circular, end sections 16,18 which open through upper and lower faces 20,22, respectively in the coupler body 12 and which are in communication with each other through a channel 24 of circular crosssection and substantially smaller diameter. The walls of the channel 24 at their juncture with the walls of the cavity end sections 16,18 are preferably tapered to facilitate filling of the cavity 14 and to continue detonation upon emergence. Detonation may become extinguished if gradual emergence provided. In FIGS. 1 and 2, the cavity 14 is shown as symmetrical about its transverse axis. This is preferred because the coupler 10 can be oriented to make either end the input end. However, it is not essential as will be further described hereafter.
The cavity 14 is filled with an explosive, such as RDX (cyclonite), PETN (pentaerythritol tetranitrate) and tetryl, so that a generally I-shaped explosive charge 26 conforming to the configuration of the cavity 14 is formed within, and coaxial with, the coupler body 12. The explosive charge 26 comprises upper and lower, disc-shaped flange sections 28,30, respectively, which are interconnected by a column 32. The upper flange 28 has an exposed face 34 which receives detonation waves from a detonator which causes initiation of the explosive in the upper flange section 28. The detonation front from the latter is transmitted through the column 32 to the lower flange section 30, which, in turn, serves to detonate any explosive adjacent to its exposed face 38. Although the point of initiation at the face 34 of the upper flange section 28 may be eccentric with respect to the longitudinal or detonation axis of the l-shaped charge 26, it is funnelled through the axially-aligned column 32 to emerge at the face 38 of the lower flange section 30 with substantially no eccentrici- The dimensions of the I-shaped explosive charge 26, and thus of the cavity 14, are determined by a number of variables which, to some extent, are unique to each application. The I-shaped charge 26 is, therefore, essentially tailored to meet the requirements of each application. If the upper flange section 28 of the I-shaped charge 26 is the input end, its diameter must be sufficient to provide an area of the exposed face 34 so that the latter can accept inputs from a wide range of possible displacements of a point of initiation on its surface from the longitudinal axis of the l-shaped charge. On
the other hand, the size of the lower flange section 30 is determined by its ability to provide an adequate input to the explosive charge, e.g., a booster charge, adjacent to it. That is, it must be sufficiently large to ensure good initiation of the booster or main charge where this device may be employed as the booster. its size will thus depend upon the type of explosive employed in the I-shaped charge 26, the explosive which is to be detonated, and the efficiency with which it, itself, is detonated. It will be understood that since different parameters govern the sizes of the upper and lower flange sections 28,30, they may be of different size and the l-shaped charge 26 need not be symmetrical about its transverse axis.
The diameter of the column 32 of the l-shaped charge 26 should be large enough to propogate the detonation wave from the upper flange section 28 to thereby cause initiation of the lower flange section 30. This will be a function of the type of explosive employed in the l-shaped charge 26 and the confinement provided by the material forming the coupler body 12. In general, the greater the degree of confinement, the smaller the diameter of the column 32 that can be used. The length of the column 32 is preferably as long as possible for a given length of I-shaped charge 26 to reduce the total amount of explosive in the precision initiation coupler in order to reduce shock transfer through the coupler body 12 which can have deleterious effects as described hereafter.
A high detonation velocity through the explosive in the l-shaped charge 26 is preferred to ensure that detonation of the explosive next to be detonated, e.g., a booster, results only from detonation of the l-shaped charge 26 and to ensure that the output of the l-shaped charge is maximized. In addition to selecting an explosive for the I-shaped charge 26 which exhibits a high detonation velocity, the material forming the coupler body 12 is preferably selected so that the detonation front is substantially confined to the explosive in the lshaped charge, that is, so that shock waves, from the explosive detonation, through the coupler body material are minimized. In this way, there is less chance that a shock traveling through the coupler body material will interfere with the detonation front propogated through the explosive and thus weaken or cause the latter to become eccentric. Additionally, by reducing shocks passing through the coupler body 12, there is less chance that, for example, an adjacent booster, will be detonated by such shocks rather than by detonation of the I-shaped charge 26, thereby ensuring correction of asymmetrical alignment by the herein-described coupler.
The material forming the coupler body 12 may be a metal such as steel or aluminum, or a plastic such as a microballoon filled phenolic. At present, it is preferable to employ steel as the coupler body material since this provides excellent detonation confinement.
In general, the precision initiation coupler 10 is placed between a detonator and a main charge. However, in practice, the coupler 10 is normally placed between a detonator and a booster which, in turn, serves to detonate a main charge. Such an arrangement is shown in the simplified warhead assembly of FIG. 3. As shown therein, a fuze body 40 is placed adjacent a booster cup 42 which, in turn, is placed against a main explosive charge 44, such as a shaped charge. These components are located within a warhead body (not shown). The fuze body 40 contains, in simplified form, a firing pin 46 and, a detonator charge 48 (which may consist of a plurality of charges).
The precision initiation coupler 10 may be positioned within the fuze body 40 or it may be positioned within the booster cup 42 as shown in FIG. 3. The booster cup 42 is divided into two sections with the coupler 10 in one section and a booster pellet 50 in the other section. The side walls of the booster cup 42 automatically align the detonation axis 52 of the coupler 10 with the detonation axis 54 of the booster pellet 50 which, in turn, is axially aligned with the main charge 44, whereas, the coupler 10 is usually not in alignment with the detonation axis 56 of the detonator 48 in the fuze body 40 due to machining limitations and tolerances. However, the axis of the detonator 48 terminates within the area of the exposed face 34 of the lshaped charge 26 so that the detonation wave from the detonator first impinges on the coupler 10 within that area.
In operation, a force impacts the front end of the warhead causing the firing pin 46 to strike the detonator 48 to cause initiation of the latter. The resulting detonation wave eccentrically initiates detonation of the explosive in the l-shaped charge 26 due to the fuze body-booster cup misalignment. However, because of the particular configuration of the I-shaped charge 26, the explosive detonation wave is forced to travel down the axially-aligned column 32 so that the lower flange section 30 of the l-shaped charge sees only a substantially axially-aligned output from the l-shaped charge 26 to the booster pellet 50.
EXAMPLE A precision initiation coupler was made up as shown in FIGS. 1 and 2. The coupler body was formed from steel and was provided with a thickness of 0.290 in. and a diameter of 0.750 inches. The cavity and, thus, the I- shaped charge, had the following dimensions: diameter of upper and lower end sections 0.4 in.; diameter of channel at its thinnest section 0.050 inches; and depth of upper and lower end sections (flange thickness) 0.075 inches. The l-shaped charge was formed from pressed RDX.
The coupler was placed in an assembly as shown in FIG. 3 except that no main charge was present. The misalignment of the detonator input to the coupler with respect to the longitudinal axis of the latter was 0.100 inches. The assembly was fired and photographs showed that misalignment of the output from the coupler was less than 0.010 inches. Comparison studies of this arrangement with and without the coupler that outputs could be increased as much as 35 percent with the coupler.
1. A precision initiation coupler, comprising:
a detonation-confining body having an l-shaped cavity formed therein and extending axially through said body; and
a detonating explosive substantially filling said shaped cavity.
2. The coupler of claim 1 wherein said detonating explosive is selected from the group consisting of RDX, tetryl and PETN.
3. The coupler of claim 2 wherein said material forming said confining body is a metal.
4. The coupler of claim 2 wherein the material forming said confining body is a plastic.
5. The coupler of claim 3 wherein said metal is one of the group consisting of steel and aluminum.
6. The coupler of claim 1 wherein said I-shaped cavity is symmetrical about its transverse axis.
7. An explosive device, comprising:
a first explosive charge;
a second explosive charge for detonating said first explosive charge, each said explosive charge having an axis ideally centering a detonation wave passing through each said explosive charge when detonated;
a precision initiation coupler comprising a detonation confining body having an l-shaped cavity axially-formed therein and extending through said body to open through opposing ends of said body, said cavity being substantially filled with a detonating explosive to provide said detonating explosive with an I-shape having a pair of exposed end faces, said precision initiation coupler positioned in axial alignment with said first explosive charge and adjacent said first and said second explosive charges so that detonation of said second explosive charge is transmitted through said precision initiation coupler to detonate said first explosive charge, said axis of said second explosive charge terminating within the area of said one exposed end face of said l-shaped detonating explosive which is adjacent said second explosive charge, whereby detonation of said second explosive charge received by said one exposed end face is funnelled through said l-shaped detonating explosive to exit at said other exposed end face in substantial axial alignment with said first explosive charge.
8. The explosive device of claim 7 wherein said first explosive charge is a booster and wherein said second explosive charge is a detonator.
9. The explosive device of claim 7 wherein said detonation-confining body is formed from a metal selected from the group consisting of steel and aluminum.
10. The explosive device of claim 7 wherein said cavity is symmetrical about its transverse axis.