GB1558740A - Detonator - Google Patents

Description

(54? DETONATOR (71) We, EMI LIMITED, a British company, of Blyth Road, Hayes, Middlesex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to detonators and especially to detonators having a rotary carrier.

A rotary detonator arrangement is used, inter alia, to permit a detonator to be kept safely away from an explosive charge until the explosive is required for use when the arrangement is armed by swinging the detonator through an arc of less than 1800, by spring action, to bring the detonator into conjunction with the charge. The time during which the detonator moves is short and can not be extended without reducing the reliability of the arrangement.

It is an object of the invention to provide an improved rotary detonator arrangement.

According to the invention there is provided a detonator arrangement utilising relative motion of a detonator and charge by revolving one on an axis through the other toward an arming position, the arrangement being such that more than one revolution about said axis occurs combined with motion along the axis and including stop means to bring the detonator and charge to rest in a position to arm the arrangement by placing the detonator to act on the charge.

The stop means may be engaged by said motion screwing the detonator and charge toward one another.

The number of revolutions during the relative motion may provide a controlled delay before the arming position is achieved.

The arrangement may include a shutter displaced only as the detonator and charge are brought to rest in the arming relation.

There may be a charge magazine having a fuze extending to the surface of the magazine, the magazine also having a screw threaded portion extending along said axis, a shutter pivoted for rotation about the axis away from a position covering the fuze at the magazine surface and a stop member for the shutter, together with a detonator carrier rotatable along said axis toward the charge magazine by engagement with the screw threaded portion, the detonator carrier having a projection to engage and displace the shutter to engage the stop member and thereby bring the detonator carrier to rest in said arming relation. The shutter may be held by a latch until engaged and displaced by the detonator carrier. The detonator carrier may be rotated by a spring.

Embodiments of the invention will now be described with reference to the accompanying drawing of a dismantled detonator arrangement.

The detonator arrangement has two main parts a detonator carrier 1 and a magazine 2. Other parts are a drive spring 3, a shutter 4 and a shutter latch 5. The magazine 2 is associated with an explosive charge (not shown) and has a fuze 21 covered by a safety barrier or septum 22. A lead-screw 23 projects from the magazine 2. A stop member 24 is positioned in a set relation to the septum 22. Shutter 4 has a blade portion 42 and a ring portion 41 which is a sliding fit on lead-screw 23 for rotation thereon without engaging on the thread of screw 23.

A latch 5 is supported in a manner not shown to pivot and engage shutter blade 42 to hold it over septum 22. Stop member 24 limits the rotation of shutter 4 away from septum 22 when the shutter is disengaged from the latch.

Detonator carrier 1 is a generally cylindrical body with a threaded bore 11 to engage the thread of lead-screw 23. An arcuate step 13 projects from the circular face nearer to the magazine and a detonator 12 is fitted to extend to the flat surface ,(not shown of the arcuate step 13. A spring 3 is engaged in hole 14 of carrier 1. The arcuate width of step 13 and the arcuate width of shutter blade 42 are chosen so that when step 13 engages blade 42 and releases it from latch 5 the blade is moved round, in the direction of arrow A, to hit stop 24 and position carrier 1 with step 13 in contact with blade 42 and detonator 12 aligned with septum 22 and close to the surface of magazine 2.

The operation of the arrangement is as follows. The arrangement is assembled with carrier 1 on lead-screw 23 and held remote from magazine 2. Spring 3 is compressed to unwind in the direction of arrow A. Shutter 4 is latched over septum 22. This is the safe position. To cause the arrangement to reach the armed position carrier 1 is released to be screwed down lead-screw 23 by spring 3 until step 13 displaces blade 42 and the carrier is stopped with detonator 12 over septum 22. The length of lead-screw 23 enables the carrier to remolve several times on screw 23 before reaching the magazine providing a substantial and predictable delay before arming occurs the shutter covering the fuze until the last revolution.If the wllole arrangement is in motion, e.g. sprinning on an axis along screw 23, which could cause carrier 1 to approach magazine 2 when released, then spring 3 can be arranged to retard the relative motion and lengthen the delay before the carrier reaches the magazine, while still holding carrier 1 against stop 24.

Clearly the length of lead screw 23, and the number of turns, can be set to produce a desired delay. Preferably the pitch of the screw is fairly coarse to ensure adequate clearance between the carrier and shutter on the revolution before the step engages the shutter. Other arrangements can be envisaged. The shutter could be omitted with some risk of premature arming. The shutter could be placed on the detonator carrier and the stop member could engage the carrier or shutter thereon. The shutter could be carried on the carrier and swept back into an angular recess in the carrier by the stop member to expose the detonator. Suitable materials will be readily apparent to those skilled in the art.

The arrangement described above provides a rotating detonator carrier arming arrangement in which the delay before arming occurs is reliably set at a longer interval than hitherto available with such arming arrangements relving on only radial motion htrough some 200 .

WHAT WE CLAIM IS:- 1. A detonator arrangement utilising relative motion of a detonator and charge by revolving one on an axis through the other toward an arming position, the arrangement being such that more than one revolution about said axis occurs combined with motion along the axis and including stop means to bring the detonator and charge to rest in a position to arm the arrangement by placing the detonator to act of the charge, 2. A detonator according to Claim 1 in which the detonator and charge are provided with mating screw-threads to direct the relative motion of the detonator and charge.

3. A detonator according to Claim 1 or Claim 2 including a shutter separating the detonator from the charge and displaceable by the final part of the relation motion to expose the detonator and charge to one another.

4. A detonator according to Claim 3 including a latch to hold the shutter until displaced.

5. A detonator according to Claim 1 having a charge magazine with a fuze extending to a surface, a screw-threaded portion of the magazine extending along said axis to mate with a screw threaded portion of a spring-driven detonator carrier to provide controlled motion of the detonator toward the fuze, a shutter pivoted for rotation about the axis away from a position on the magazine surface covering the fuze, a projection on the detonator carrier to engage and displace the shutter into engagement with the stop member and thereby bring the detonator carrier to rest in said arming position.

6. A detonator arrangement according to any one of the preceding claims in which an arming delay is provided by the time for at least one rotation of a detonator carrier during motion toward an arming position.

7. A detonator arrangement substantially as herein described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. position carrier 1 with step 13 in contact with blade 42 and detonator 12 aligned with septum 22 and close to the surface of magazine 2. The operation of the arrangement is as follows. The arrangement is assembled with carrier 1 on lead-screw 23 and held remote from magazine 2. Spring 3 is compressed to unwind in the direction of arrow A. Shutter 4 is latched over septum 22. This is the safe position. To cause the arrangement to reach the armed position carrier 1 is released to be screwed down lead-screw 23 by spring 3 until step 13 displaces blade 42 and the carrier is stopped with detonator 12 over septum 22. The length of lead-screw 23 enables the carrier to remolve several times on screw 23 before reaching the magazine providing a substantial and predictable delay before arming occurs the shutter covering the fuze until the last revolution.If the wllole arrangement is in motion, e.g. sprinning on an axis along screw 23, which could cause carrier 1 to approach magazine 2 when released, then spring 3 can be arranged to retard the relative motion and lengthen the delay before the carrier reaches the magazine, while still holding carrier 1 against stop 24. Clearly the length of lead screw 23, and the number of turns, can be set to produce a desired delay. Preferably the pitch of the screw is fairly coarse to ensure adequate clearance between the carrier and shutter on the revolution before the step engages the shutter. Other arrangements can be envisaged. The shutter could be omitted with some risk of premature arming. The shutter could be placed on the detonator carrier and the stop member could engage the carrier or shutter thereon. The shutter could be carried on the carrier and swept back into an angular recess in the carrier by the stop member to expose the detonator. Suitable materials will be readily apparent to those skilled in the art. The arrangement described above provides a rotating detonator carrier arming arrangement in which the delay before arming occurs is reliably set at a longer interval than hitherto available with such arming arrangements relving on only radial motion htrough some 200 . WHAT WE CLAIM IS:-

1. A detonator arrangement utilising relative motion of a detonator and charge by revolving one on an axis through the other toward an arming position, the arrangement being such that more than one revolution about said axis occurs combined with motion along the axis and including stop means to bring the detonator and charge to rest in a position to arm the arrangement by placing the detonator to act of the charge,

2. A detonator according to Claim 1 in which the detonator and charge are provided with mating screw-threads to direct the relative motion of the detonator and charge.

3. A detonator according to Claim 1 or Claim 2 including a shutter separating the detonator from the charge and displaceable by the final part of the relation motion to expose the detonator and charge to one another.

4. A detonator according to Claim 3 including a latch to hold the shutter until displaced.

5. A detonator according to Claim 1 having a charge magazine with a fuze extending to a surface, a screw-threaded portion of the magazine extending along said axis to mate with a screw threaded portion of a spring-driven detonator carrier to provide controlled motion of the detonator toward the fuze, a shutter pivoted for rotation about the axis away from a position on the magazine surface covering the fuze, a projection on the detonator carrier to engage and displace the shutter into engagement with the stop member and thereby bring the detonator carrier to rest in said arming position.

6. A detonator arrangement according to any one of the preceding claims in which an arming delay is provided by the time for at least one rotation of a detonator carrier during motion toward an arming position.

7. A detonator arrangement substantially as herein described with reference to the accompanying drawing.