US 3653792 A
A high pressure shaped charge device having a predetermined external configuration for the explosive material, the configuration being calculated and shaped in such a manner as to optimize the force of an imploding pressure wave.
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Description (OCR text may contain errors)
United States Patent 1151 3,653,792 Garrett [451 Apr. 4, 1972 HIGH PRESSURE SHAPED CHARGED Referencefi Cited UNITED STATES PATENTS [721 Garrm, 314 Bmkside, Bryan 3,022,544 2/1962 Coursen et a] ..264/84 1 77801 3,220,103 11/1965 Simons "264/84 x 22 Filed: Aug. 20, 1970 Primary Examiner-H. A. Kilby, Jr. PP 65,599 Attorney-Bernard A. Reiter Related US. Application Data  ABSTRACT 'P of 870,323, which is a A high pressure shaped charge device having a predetermined dlVlSlOn Of 561'. 1968, external configuration for the explosive material, the configuration being calculated and shaped in such a manner as to optimize the force of an imploding pressure wave.  US. Cl ..425/1, 18/5 H, 18/DIG. 15,
264/84, 425/78 10 Claims, 2 Drawing Figures  Int. Cl. .3290 23/00  Fieldofsearch ..l8/1R,5H,16R,DIG.15,
l8/DlG. 26, DIG.28; 425/1; 264/84 PATENTEDAPR 4 I972 Donald R. Garrett IN VE N TOR BY Bernard A. Re/ter ATTORNEY HIGH PRESSURE SHAPED CHARGED DEVICES BACKGROUND OF THE INVENTION This application is a continuation-in-part of my prior pending application Ser. No. 870,323, which application is a division of my prior application Ser. No. 708,331, filed Feb. 26, 1968 now U.S. Pat. No. 3,499,732.
This invention relates generally to the formation of solid compacts from powdered metals and/or powdered refractory materials. More specifically the invention pertains to the formation of compacts having a high and substantially uniform density and in which varying pressure phases can be quenchably retained.
Relatively recent technological advances have enabled the formation of compacts from powdered materials through the utilization of forces from explosive devices. It is known that the effective use of a charge for this purpose is markedly enhanced if the forces upon detonation are directed inwardly,
rather than outwardly, for the reason that the direction of force is more easily concentrated. Concentration of the forces produces higher temperatures and pressures than might otherwise be realized, and thus satisfactory compaction of the powdered material is more likely. In using implosive techniques for compaction purposes, the shape or configuration of the charge itself is of critical importance because it affects the directional movement of the shock wave which emanates upon detonation. Therefore, in view of the fact that the pressure and temperature of any compaction technique represents the governing parameters in the effectiveness thereof, and further since the shape of the explosive charge is found to influence the magnitude of the pressure and temperature, it is an object of this invention to provide an apparatus and method which optimizes the configuration of the charge in order to produce the highest temperature and pressure possible.
The invention in its broader aspect comprises a method and apparatus for quickly and inexpensively forming high density compacts from powdered material. In other aspects, the invention discloses an apparatus and method for optimizing the results of an implosive force upon detonation. Briefly, the invention comprises two conically shaped charges abutted together at their bases. A specimen of some chosen powdered material is centered in the plane of the bases of the two shaped charges. Heretofore shaped charges required a supporting liner in order to retain the desired configuration and for this purpose a copper or other material in appropriate shape was used. In the preferred form of the present invention the two conical explosive charges utilize no copper liner or other support and instead are configured to utilize predetermined 'cone apex angles in order to produce a nearly spherical but somewhat conical imploding wave. The spherical imploding wave is highly desirable because it inherently optimizes and centralizes the forces of compaction at a common intersecting point. If the cones are given a slight ellipticity of the proper configuration, a perfectly spherical imploding wave may be developed. Thus, a primary feature and advantage of the invention is the provision for a substantially spherical imploding wave. Another primary feature and advantage of the invention is the provision for a balanced imploding wave, that is an imploding wave characterized by a substantially equal distribution of implosive forces.
Numerous features and advantages of the invention will become apparent upon a reading of the following detailed description and claims, when read in conjunction with the accompanying drawings, wherein:
FIG. 1 schematically illustrates the structural arrangement of a powder specimen in relation to abutting cones made of an explosive material, preparatory to their simultaneous ignition.
FIG. 2 illustrates an imploding particle velocity wave, moving axially, subsequent to cone ignition.
DETAILED DESCRIPTION OF THE INVENTION This invention makes use of the terms detonation wave velocity" and particle wave velocity. The former refers to the velocity at which ignition moves along the length of an explosive charge while the latter pertains to velocity at which the force wave produced by the ignition moves in some given direction.
With reference to FIG. 1, there is shown a schematic arrangement in which the invention is utilized in its preferred form. Centrally disposed is a specimen 3 of powdered material which is to be compacted or clad with some other material. Surrounding the specimen is a formation of clay 5, or the like, shaped to conform to the configuration of a pair of conical explosives 7, 9, which are disposed thereover. The clay not only supports the explosives 7, 9 but also serves to shield specimen 3 from excessively high temperatures. The clay further serves as a hydraulic medium for transmitting pressure. Conical explosives 7, 9 are made in accordance with predetermined thickness and are disposed in abutting base to base relationship with one another so that the apices ll, 13 of each conical explosive is axially aligned. The apices ll, 13 are intended to serve as the ignition points for detonating the shaped charges. Such ignition must be substantially simultaneous in order to produce a balanced wave. Upon ignition it may be visualized that an implosive force isproduced. This implosive force from each cone propels itself inwardly due to the angular relationship Theta (0) of the walls to each other. This angular relationship causes the explosive forces, i.e., the particle wave, and consequent pressure to be directed inwardly at varying angles. In accordance with the teachings of this invention, the inwardly directed explosive forces and pressures are centralized at a specific point in order to concentrate and maximize the results of the detonation. This is accomplished by predeterrnining the appropriate apex angle with consideration being given to the particle velocity and detonation velocity of the explosive used. If the angle 0 is improperly calculated a blowout or blowthrough in the imploding wave will occur, thereby destroying the ability to produce maximum pressure and optimal temperature. There then results a turbulent pressure environment around the specimen, much like a conventional explosion, rather than a coherent pressure or particle wave.
For exemplary purposes there is set forth the following description and application of the invention through the use of the explosive material RDX. It will readily be recognized that the principles set forth are applicable to other explosive materials and that the teachings are readily correlated in order to determine the optimal apex angles for any given explosive charge. In FIG. 2 there is shown a mangified view subsequent to ignition. Upon ignition of the explosive material in explosive cone 9 at the apex 11 there is produced an imploding wave P It may be visualized that the angular relation of the walls determine the direction of movement of any given implosive force component P since such component moves substantially perpendicularly to the wall. Thus, by disposing the cone walls at some predetermined angle, each individual pressure component P P P etc., of the wave P may be given a direction which, in effect, gives the wave itself a direction.
At a given time t after ignition at the apices of the explosive material of each cone 7, 9 the detonation wave D,, will have traveled a predetermined distance S from the ignition point 1,, see FIG. 2. If it is assumed that the detonation wave D moves at four times the velocity of the particle wave P such as is the case with the explosive RDX or DuPont Detasheet, then when the detonation wave D reaches the point X at the base of the explosive surface, the particle wave will have traveled a distance one-fourth X in a direction normal to the explosive surface. For example, from the time that the detonation wave D travels from its point A to the point X at P, the particle wave will have moved normal to the explosive surface at point A a distance one-fourth of the distance covered between I and t More specifically the particle wave will have moved inwardly through the distance S as shown in FIG. ll. While the detonation wave D is moving from point B to the point X at P the particle wave P will have moved a distance normal to the explosive surface at point B equal to S When the detonation wave D, has moved from point C at distance 8, along the surface to the point X at P the particle wave P,, will have moved a distance normal thereto equal to S If it were assumed that the angle formed between the particle wave and the explosive surface at the point X was designated Alpha; then Further, if it were assumed for exemplary purposes that the length of a side of the cone was 2.56 inches, then by the application of the Pythagoreon Theorem:
9 1.42 tan- .689
34.8: therefore 6 69.6
Thus in the above example it is assumed that the particle wave P, moves perpendicular to the surface of the cone at a velocity one-fourth that of the detonation wave D Further in accordance with the application of known trigonometric principles, it is seen that the relative distances S and S of the Particle wave from the surface may be calculated at any given time I. Since the particle wave is assumed to move inwardly at equal velocities from any side of the conical surface it is seen that the apex of the particle wave will move axially from the ignition point 1, toward the base of the cone. It is likewise clear from the example above that the clay surrounding the specimen should be of truncated configuration in which the height of the truncated clay cone is of the length r wherein r is the radius also of the base of the cone. Hence for any explosive material with a detonation velocity to particle velocity ratio of 4/1 the optimal angle of the cone sides for implosive purposes is 69.6". With such angular relationship between the sides there will be produced a substantially spherical imploding wave.
in summary, it should be recognized that the teachings set forth hereinabove are intended only to exemplify the relative relationships of the governing factors involved in accomplishing a balanced spherical imploding wave for compacting powdered materials. It is believed readily evident that appropriate modifications to the shape of the cone may be made in predetermined fashion in order to produce an alternate particle wave form if the same is desired. For example, through the application of known trigonometrical relationships, calculations may be made for the configuration of a cone that would produce an elliptical particle wave if the same were deemed advisable. Through the use of these teachings in conjunction with shaped charges numerous efficiencies and advantageous results may be accomplished in order to maximize compaction, sintering, cladding and high pressure phase transforation not otherwise possible with the same amounts of explosive and powdered material. Still other modifications of the present invention are possible. For example the inner mold can take varying configurations in order to achieve the desiredresults and it could be fabricated from various materials such as styrofoam, mud, papier mache, or the like. Therefore it is intended that all of the matter set forth in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not at all in a limiting sense.
Having thus described the invention, that which is claimed and desired to be secured by United States Letters Patent is:
1. In an apparatus for producing compacts from powdered materials through the utilization of an implosive pressure wave created upon detonation of charge comprising a powder specimen of predetermined quantity,
charge means of predetermined size sufficient to produce a pressure and temperature upon detonation to transform the powder into a solid physical state, said char e means consisting of a pair of shaped bodies in WhlC each is characterized by a base and an apex, the apices being adapted to serve as points for ignition, the bases of said shaped bodies being disposed in abutting relation to one another and the powder specimen disposed in the plane of said abutting bases so that upon detonation of said points of ignition thereis created a particle wave that is uniformly directed toward said specimen.
2. The apparatus of claim 1 wherein the apices of said shaped bodies reside on a common axis that includes as a point thereon the center of said abutting bases so as to thereby enhance the production of a balanced particle wave.
3. The apparatus or claim 1 wherein the said shaped bodies are of substantially conical configuration and in which the angular relation of the side wall is constant with respect to the axis so as to enhance the production of a balanced particle 4. The apparatus of claim 1 wherein the angular relation of the side walls of said shaped bodies is constant with respect to the axis so as to enhance the production of a balanced particle 5. The apparatus of claim 2 wherein the said shaped bodies are of substantially conical configuration and in which the angular relation of the side wall is constant with respect to the ax s.
6. The apparatus of claim 2 wherein the angular relation of the side. walls of said shaped bodies is constant with respect to the axis so as to further enhance the production of a balanced particle wave.
7. The apparatus of claim I wherein the angular relation of the side walls of such shaped bodies to the axis thereof is calculated to produce a somewhat conical but substantially spherical imploding particle wave, said angular relationship being determined by the ratio of the detonation wave to the particle wave of the charge used.
8. The apparatus of claim 2 wherein the angular relation of the side walls of said shaped bodies to the axis thereof is calculated to produce a substantially spherical imploding particle wave, said angular relationship being determined by the ratio of the detonation wave to the particle wave of the charge used.
9. The apparatus of claim 5 wherein the angular relation of the side walls of said shaped bodies to the axis thereof is calculated to produce a substantially spherical imploding particle wave, said angular relationship being determined by the ratio of the detonation wave to the particle wave of the charge used.
10. The apparatus of claim 9 wherein said shaped bodies are structurally reinforced by inner mold means surrounding the specimen and which conform to the interior shape of the bodies, the material of the inner mold means being adapted to faithfully transmit the pressures of compaction.