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United States Patent Office 3,334,536
Patented Aug. 8, 1967

1 2
two parts are held in attachment by the bolt and the ex-
3,334,536 plosive nut.
RELEASABLE NUT WITH RADIAL AND Many of the explosion nuts heretofore known, and still
LONGITUDINAL LOCKOUT in use, are reliable in actuation only if they are massively
John P. Armstrong, San Fernando, Calif., assignor to 5 constructed. If an attempt is made to reduce them in size,
Bermite Powder Company, North Hollywood, Calif.,
a corporation of California actuation becomes unreliable unless the explosive charge
Filed Mar. 23, 1964, Ser. No. 354,074 is large enough to destroy the nut or tear it loose from
7 Claims. (CI. 85-33) the nut-held part in a large percentage of its operations.
It is not merely the disadvantage of such devices that they
This invention relates to releasable nuts, such as ex- 10 are destroyed in being used and cannot be reused by
plosive nuts in which a set of threaded segments are merely threading in a new squib; they are dangerous to
driven out of engagement with a bolt by a device actu- persons who may be within the vicinity of the nut at
ated by squib-produced gases. More particularly, this in- the time of the explosion, for example, the astronaut
vention relates to a releasable nut in which the segments himself. Also, in applications on unmanned satellites and
are released and locked out of engagement with the bolt 15 the like, valuable instrumentation, in the vicinity of the
threads in a two-step sequence: first, radial release by explosive nut may be damaged by fragments, or by the
longitudinal displacement of an enclosing sleeve struc- nut itself.
ture, and second, by positive outward displacement and It is not only flying fragments from explosive nuts that
lockout by a telescoping cone structure of novel con- cause undesirable effects on other devices nearby. For
struction. 20 example, many satellites rely upon solar cells for a con-
In a preferred form of the invention, actuation is tinuing source of power. Many of the lightweight ex-
achieved by an entirely enclosed explosion, and the fea- plosive nuts heretofore known have discharged their ex-
tures of releasability and lockout also act to prevent the plosion gases, at the time of the explosion, in the vicinity
escape of explosion gases. of the nut. Particles in these gases have then coated the
The use of explosion nuts and explosion bolts have 25 solar cells, and greatly reduce their capacity for energy
experienced vastly increased application in recent years generation.
because of their convenience for use in many applica- In general, explosive nuts and bolts rely upon a seg-
tions in space technology. For example, upon a signal mented thread system, which becomes releasable upon
from the earth or from within the device itself, an or- explosion. Thus, in the present invention, a set of in-
biting space dev.ice can impart electrical ignition to ex- 30 ternally threaded segments form a sleeve enclosing and
plosive squibs within such nuts, so as to detach an ex- mating with the threads of the bolt. It is much preferred
hausted launching vehicle from the orbiting payload. that four quarter segments be used, but the invention in
Astronauts have made quick escapes from a satellite pod, its most generic form might be used with fewer than
after return to the earth's surface, by exploding bolts or four segments, or with more than four segments. When
nuts to release a hatch cover. In addition to these widely 35 only two or three segments are used, the segments must
known applications, variations of the explosive nut or be moved a greater distance in order to insure release,
bolt are beginning to be proposed for application in sub- and this is usually a disadvantage. It is rare that any ad-
marine devices, or for devices to be used in environments vantage is gained ,by using more than four segments. Re-
of high radioactivity. gardless of the number of segments, most explosive nut
One of the major objects of the present invention is 40 designs heretofore known have been susceptible to fail-
to vastly increase the possible applications of explosion ure because of lack of certain control over the disen-
nuts, and to eliminate many of the objectionable features gaging movement of the segments, and their sure lockout
heretofore associated with them. Thus, the explosion nut in a disengaged position. There has always been the dan-
of this invention could be used in connection with fire ger of a certain percentage of failures. from an erratic
escapes, shipboard hatches, safety devices on construction 45 movement on the part of one or more segments, or the
cranes or high speed rotating machinery. tendency of one segment to bounce back into engagement
The term, ''explosive nut," should not be taken as lim- with the escaping bolt, jamming it and preventing its full
iting the utility of the invention to devices in which ac- release.
tuating pressure is obtained by the gases generated by the Previcous designs have attempted to overcome the fore-
burning of a squib, although it will be appreciated, but 5o going objection by insuring lockout, arid it has generally
this is by far the preferred form in most applications. been by means which deform the threaded segments, or
However, in its most generic form, the invention may be some other part of the explosive nut, so that these parts
used with means of pressure actuation other than by ex- are not reusable.
plosion gases. The design of an explosive nut system always presents
In a typical explosive nut application, the entire explo- 55 the question as to whether or not it is desired to forcibly
sion nut device is housed in a body which is screwed or expel the bolt, •or merely to release it. Both methods of
bolted to the surface of a plate or wall comprising part operation have their proper applications. Most previously
of one member to be separated. However, in some ap- known explosive nut designs have been suitable only for
plications, it is not necessary that the explosive nut be one or the other.
held on said member by anything except the bolt which 60 Another problem with previously known explosive nut
it is adapted to receive. In either case, the member upon designs has been that of rigidity, reliability, and structural
which the nut is carried will be designated for purposes strength prior to explosion.
of identification as the nutaheld part. The present invention meets and overcomes all the
A second part, which may be referred to for purposes above objections, by providing a design which can be
of identification as the bolt-head part, is typically a sec- 65 made extremely light in weight, can be reliably actuated
ond plate or wall mating with the nut-held part, both by small squi-bs, can wholly contain the actuating explo-
parts having mating holes for the passage of the threaded sion, and yet can be varied in design to fit almost any
shank of the bolt to mating threads inside the explosion explosive nut application.
nut. However, the invention is not limited in any way as In the device of the present invention, the threaded
to the shape of the two mating parts, or the bolt-head, 70 segments are precisely controlled in their movements by
or the holes or other means of reception by which the a system of telescoping conical surfaces. Such an arrange-