Crimping of detonators

Abstract

A device for crimping the mouth of a detonator housing comprises a pair of opposed jaws reciprocally movable relative to each other, and a plurality of toothed segments on each jaw. The segments are moveable, are located in a jaw cavity, and together form a segmented ring. The side faces of each segment converge from a broad radially outer end towards a toothed radially inner narrow end. A resiliently stressable biasing element is provided between each adjacent pair of segments. The biasing elements act to space the segments of each pair apart when the jaws are spaced apart from each other, and also act to permit the segments, in response to movement of the moveable segments arising from the closing of the jaws, to abut against one another in series when the jaws are tightly in contact with each another, to form the segmented ring.

1 . A device for crimping the mouth of a metal detonator housing around an initiating element protruding into the housing through the mouth, the device comprising a pair of opposed jaws, at least one which is movable relative to the other and is reciprocally mounted so that at least one of the jaws is reciprocally movable alternately towards and away from the other jaw to successively bring the jaws tightly into contact with each other and then to space the jaws apart from each other each jaw being provided with three toothed segments arranged side-by-side in series on each jaw, all of the segments being movable and being in the form of movable inserts located in a single cavity provided in each jaw for receiving the inserts, each segment having a pair of side faces whereby the segment abuts an adjacent segment when the jaws are tightly in contact with each other so that the segments of the jaws together form a segmented ring, the side faces of each segment converging from a broad radially outer end of the segment towards a toothed radially inner narrow end of the segment, each segment thereby having a tapering shape when viewed in a direction parallel to the axis of the ring, with the teeth of each segment being parallel to said axis;
 a resiliently stressable biasing element provided between each adjacent pair of segments in a jaw, the biasing element acting to space the segments of the pair apart when the jaws are spaced apart from each other and acting to permit the segments, in response to movement of the moveable segments arising from the closing of the jaws, to abut against one another in series when the jaws are tightly in contact with each another, to form the segmented ring, the ring defining, at its centre, a passage having a toothed cross-sectional outline provided by the toothed narrow ends of the segments for holding a crimped mouth of a detonator, the mouth having been crimped by the toothed inner ends of the segments in response to radially inward movement of the segments caused by the tight closing of the jaws.   
   
   
       2 . The device according to  claim 1 , wherein each cavity provides one or more abutment faces for abutting respectively against the broad ends of the movable segments. 
   
   
       3 . The device according to  claim 2 , wherein the abutment faces are flat and wherein the broad ends of the movable segments have radially outwardly facing surfaces which are also flat. 
   
   
       4 . The device according to  claim 2 , wherein a radial projection projects radially outwardly from the outer surface of the broad end of the segment into a tangential slot provided in the associated abutment face of the cavity. 
   
   
       5 . The device according to  claim 1 , wherein each biasing element is an elastomeric block which is held captive in a cavity in the side face of one of the segments of the pair of segments between which it acts. 
   
   
       6 . The device according to  claim 5 , wherein each elastomeric block projects tangentially outwardly from its cavity relative to the axis of the ring when the jaws are spaced apart from each other, thereby acting to space apart the segments of the pair, and is compressed and forced into its associated cavity by the side face of the other segment of the pair when the jaws are tightly in contact with each other. 
   
   
       7 . The device according to  claim 5 , wherein each elastomeric block is cylindrical in shape, being located in a correspondingly part-cylindrical cavity having an axis which is parallel to the axis of the ring. 
   
   
       8 . The device according to  claim 1 , wherein each jaw comprises an elongated rectangular flattened bar, the bar being longer than it is wide and wider than it is thick so that it has a pair of major faces spanning the length and width of the bar; a pair of side edge faces spanning the length and thickness of the bar; and a pair of end edge faces spanning the width and thickness of the bar, the bars abutting against each other by means of a pair of opposed side edge faces thereof, when the jaws are in the tightly closed condition. 
   
   
       9 . The device according to  claim 8 , wherein the cavities holding the respective series of segments are semi-regular-polygonal indentations in the respective opposed side edge faces of the bars and extend from one major face of the bar to the other. 
   
   
       10 . The device according to  claim 9 , wherein the axes of the semi-regular-polygonal indentations are parallel to the axis of the ring. 
   
   
       11 . The device according to  claim 8 , wherein a cover plate encloses the major face of each bar and acts to hold the segments and biasing elements in place against axial movement thereof in a direction parallel to the direction of the ring axis. 
   
   
       12 . The device according to  claim 11 , which includes a guide pin protruding from each of the segments, with a complementary guide slot in which each of the guide pins is movingly located, being provided in the cover plate. 
   
   
       13 . The device according to  claim 8 , wherein the jaws are provided respectively on their side edge faces which abut when the jaws are tightly in abutment, with a guide pin and an opposed tubular guide socket, the pin entering the socket when the jaws approach each other and leaving the socket when the spacing between the jaws is increased sufficiently, as the jaws leave each other.