A non-electrical detonator including an elongate sleeve with a main charge, an initial charge, a delay composition and a gas chamber therein, a subassembly for firing the delay composition including a percussion cap engageable by a double ended striking pin which can be inserted in either direction within a tube, and a fuse held with an elastic plug to operate the striking pin.

BACKGROUND OF THE INVENTION 
The invention relates to non-electrical detonators operated by a fuse 
driving a striking pin to fire a percussion cap. 
More particularly, the invention relates to a detonator assembly which 
contains a main charge, initial charge, and a delay element. The charges 
are fired by a percussion cap which is in a unique assembly operated by a 
double ended striking pin movable against a compressible spherical body 
and operated by the pressure of the fuse. 
A detonator of this type is disclosed in European Patent EP-A1 0253955, 
particularly in FIG. 4 of the patent. In this structure if the fuse or the 
primer tube, that is, the chemical substance contained therein is ignited, 
the resultant pressure wave propagates at high velocity and propels the 
striking pin against the percussion cap whereupon the igniter is 
detonated. The striking pin in this arrangement is guided partially in the 
fuse and partially in the percussion cap retainer. 
However, this arrangement has proven disadvantageous in certain aspects 
such as when the detonator is assembled and crimped, which is accomplished 
by insertion of the fuse in the sleeve employed in an interposed elastic 
plug and subsequent deformation of the sleeve, a fuse section may then 
also become restricted resulting in inhibition of the mobility of the 
striking pin. This, of course, can make the detonator become ineffective. 
Moreover, the effective surface area of the striking pin upon which the 
gas pressure of the fuse can act is limited to the clear cross section of 
the fuse. 
FEATURES OF THE INVENTION 
It is an object of the present invention to eliminate the disadvantages 
discussed above with respect to the alluded to prior art device. 
A further object of the invention is to provide an improved detonator which 
has features of improved assembly eliminating the possibility of 
misassembly which can occur in structures heretofore available. 
A further object of the invention is to provide a simplified overall 
detonator construction which is more reliable in operation than 
arrangements heretofore used. 
In accordance with a feature of the invention, disadvantages of the 
arrangement above described in particular is achieved in that a retainer 
is provided for a striking pin which is essentially of hollow cylindrical 
shape and the entire striking pin is located in and guided by the 
retainer. 
With the striking pin now entirely located in and guided by the hollow 
cylindrical retainer, there is no longer any danger that the mobility of 
the striking pin will be adversely affected by the crimping of the sleeve 
during detonator manufacture. Moreover, the entire cross section of the 
striking pin is now exposed to the pressure wave of the fuse thus giving 
maximum impact force to the striking pin. 
A further disadvantage of the detonator described in the above mentioned 
European patent lies in the fact that the striking pin may hit the 
percussion cap if the detonator is dropped thus causing unintentional 
detonation. With the features of the present invention, this is avoided in 
that there is an elastic body located between the percussion cap and the 
striking pin. This elastic body has to be penetrated by the striking pin 
for detonation to occur. This elastic body retains the striking pin a safe 
distance from the percussion cap until the striking pin is intentionally 
propelled forward by the shock wave of the fuse. As a result, accidental 
and unintentional firing of the detonator is prevented with reliability. 
In the case of heretofore known non-electrical detonators, it has been the 
practice that the percussion cap is merely inserted in the retainer. This 
has meant that the position of the percussion cap is not precisely 
defined. This has led to differing initial clearances between the striking 
pin and the percussion cap. This causes a variance in firing behavior from 
detonator to detonator. 
In order to avoid this disadvantage, it is recommendable and is the case in 
the present invention to secure the percussion cap in the retainer by 
means of a supporting tube which surrounds the striking pin. Maximum 
clearance between the striking pin and the percussion cap is thus clearly 
defined. 
The normal design employed for striking pins in non-electrical detonators 
is such that at one end there is located the surface which reacts to gas 
pressure. At the other end of the striking pin is located a projection 
which penetrates the percussion cap. When assembling the detonator, it is 
necessary to insure that the striking pin is positioned the correct way 
around, that is, that the striking pin is always assembled in the same 
axial direction. The additional time and expense associated with this 
orientation can be avoided by the present arrangement. Also, the present 
arrangement will avoid misassembly which can result in inoperativeness of 
the detonator. This is accomplished in the present arrangement by making 
the striking pin of symmetrical design so that each axial end is the same. 
With such a design, either end of the striking pin can be inserted first 
so there is no longer any need to insure that it is being installed in the 
correct axial direction. In the present arrangement, the entire unit 
provides a compact overall sleeve which is capable of rapid assembly and 
capable of simplified completion of manufacture. 
Other advantages, features and details will become more apparent with the 
teaching of the principles of the invention in connection with the 
disclosure of the specification, claims and drawings, in which:

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The non-electrical detonator shown in its entirety in FIG. 1 includes a 
sleeve 3 which is closed at one end, shown in the drawing as the upper 
end. At the other open end, is inserted a fuse or a primer tube 1. This 
fuse is fixed in the sleeve open end by being held within an elastic plug 
and the sleeve is deformed against the elastic plug by annular 
indentations with the sleeve being formed of a light weight metal or 
plastic. 
Also inserted in the sleeve is a firing pin assembly which is shown in 
detail in FIG. 3, and as shown, it is held within the sleeve in FIG. 2. 
A striking pin is shown at 4 capable of free axial movement within a hollow 
cylindrical retainer 5. Actually, the retainer holds a hollow cylindrical 
tube 6 within which the firing pin slides as indicated by the arrow in 
FIG. 3 which indicates the direction in which the striking pin must move 
to fire the percussion cap. 
Within the cylindrical retainer 5 at the upper end thereof and held therein 
by a slight flange at the upper end of the retainer is a percussion cap 7. 
The tube 6 within which the striking pin slides presses up axially against 
the percussion cap to hold it in position within the hollow retainer 5. 
The striking pin 4 is designed such that is has a projecting pin at either 
end with the projecting pin having the capabilities of firing the 
percussion cap. This has the advantage that in assembly, the striking pin 
4 can be installed in either axial direction and the assembler need not 
check to be sure that the striking pin is installed in one axial direction 
only. 
Between the striking pin 4 and the percussion cap 7 is an elastic generally 
spherical body 8 which acts as a compression spring. This elastic body 
which can be formed of a plastic material, firmly holds the striking pin 
in its initial position at the base of the tube 6 and separates the 
striking pin from the percussion cap 7. 
The retainer 5 and the supporting tube 6 can be assembled in a common 
operation. The supporting tube 6 has a flanged-in or lower reduced opening 
so that the striking pin can be first dropped into the upper end and the 
spherical body placed in thereafter. The supporting tube then can be slid 
up into the hollow retainer 5 and the hollow retainer be crimped inwardly 
or reduced at its lower end. This crimping spaces the striking pin 
upwardly from the lower end of the retainer and as a result, the fuse 1 
does not come in contact with the striking pin, but a space remains as 
shown in FIG. 2. In the sleeve 3, the position of the retainer 5 is fixed 
by an annular restriction 14 which positions the top end of the retainer, 
and the crimping which holds the elastic plug in place holds the lower end 
of the retainer. The retainer, thus, is in a tight interference fit within 
the sleeve, and if the sleeve is formed of a metal, the parts are all held 
together and the sealing seals all of the chemical constituents of the 
explosive charges and other materials within the sleeve. 
In the space between the retainer 5 and the closed end of the sleeve 3 is 
an igniter which has an initial charge 11 and a main charge 12. Below that 
is a delay composition 10 which is contained in a delay element 9. A gas 
chamber 13 provides a free space between the percussion cap and the delay 
element. 
In operation when the fuse 1 is ignited, the pneumatic energy of the fuse 
acts like a shock wave on the striking pin 4 and this is propelled in the 
upward direction indicated by the arrow in FIG. 3. The forcible upward 
movement of the striking pin overcomes the resistance of the elastic body 
8 and detonates the percussion cap 7. In the ensuing sequence, this 
ignites the delay composition 10 in the delay element 9. The gas chamber 
in which the combustion gases gather remains closed and this results in a 
high degree of accuracy with respect to the delay time. After the 
pyrotechnic delay composition 10 has been burned through, the flame 
reaches the initial charge 11 which as a sequence continues, ignites the 
main charge 12 whereupon the detonator explodes. 
Thus, it will be seen that the firing pin assembly arrangement is such that 
inadvertent dropping of the sleeve will not accidentally create a 
mechanical pressure on the striking pin to inadvertently fire the 
detonator. Also, the arrangement provides a rigid reliable secure 
detonator assembly which is reliable in time of operation and compact for 
ease of handling.