Tamping Device

Abstract

A tamping device ( 10 ) for plugging an open end of a blasting hole used in a mine blasting application comprising an expandable sleeve ( 20 ) having a bore. The sleeve is configurable between circumferentially expanded and circumferentially retracted positions. An actuation member ( 40 ) having a head section ( 41 ) is at least partially locatable inside the expandable sleeve. The head section and the expandable sleeve are adapted in order for relative longitudinal movement between the head section and the expandable sleeve, to cause the sleeve to be manipulated from the retracted position to the expanded position.

1 . A tamping device, suitable for use in plugging an open end of a blasting hole, the tamping device comprising:
 an expandable sleeve having a bore, the sleeve being manipulatable between a circumferentially expanded position and a circumferentially retracted position;   an actuation member having a head section;   the head section being at least partially locatable inside the expandable sleeve; and   the head section and expandable sleeve being adapted in order for relative longitudinal displacement between the head section and the expandable sleeve to cause the sleeve to be manipulated from the circumferentially retracted position to the expanded position.   
   
   
       2 . The tamping device of  claim 1  wherein the expandable sleeve in use remains longitudinally stationary, and the actuation member is longitudinally displaceable relative to the sleeve. 
   
   
       3 . The tamping device of  claim 2  wherein the actuation member is longitudinally displaceable by exerting a tensile force thereon. 
   
   
       4 . The tamping device as claimed in  claim 1  wherein an outer surface of the head section and an inner surface of the sleeve are tapered relative to one another. 
   
   
       5 . The tamping device of  claim 4  wherein both the outer surface of the head section and the inner surface of the sleeve are of tapered configuration. 
   
   
       6 . The tamping device as claimed in  claim 1  wherein the sleeve defines a plurality of circumferentially spaced longitudinal slots that divide the sleeve into a plurality of gripping members. 
   
   
       7 . The tamping device of  claim 6  wherein the gripping members are at least partially resilient, and are radially outwardly manipulatable relative to the actuation member, so as to render the sleeve expandable. 
   
   
       8 . The tamping device as claimed in  claim 7  wherein an outer surface of each gripping member is at least partially serrated. 
   
   
       9 . The tamping device as claimed in  claim 1  wherein a longitudinal, elongate groove is provided in the sleeve for receiving a detonator cord. 
   
   
       10 . The tamping device as claimed in  claim 1  wherein the head section is configured and dimensioned to have a circumference complementary to an inner surface of the sleeve. 
   
   
       11 . The tamping device as claimed in  claim 1  wherein the actuation member comprises a stem section extending from the head section to a handle section. 
   
   
       12 . The tamping device of  claim 11  wherein the stem section is of a lengthwise tapered configuration. 
   
   
       13 . The tamping device of  claim 12  wherein a tapering angle is less than 5°. 
   
   
       14 . The tamping device as claimed in  claim 11  wherein the stem section is located inside a resilient retaining formation provided on the sleeve, the retaining formation engaging the stem section as the stem section is displaced relative to the retaining formation. 
   
   
       15 . The tamping device of  claim 11  wherein the stem section includes a zone of reduced diameter between the head section and the handle section. 
   
   
       16 . The tamping device of  claim 15  wherein the zone of reduced diameter is adjacent the handle. 
   
   
       17 . The tamping device of  claim 15  wherein the zone of reduced diameter is in the form of a circumferential groove provided in the stem section. 
   
   
       18 . The tamping device as claimed in  claim 15  wherein the zone of reduced diameter is configured such that the handle section becomes detached from the stem section when a predetermined tensile force is applied on the handle section. 
   
   
       19 . The tamping device as claimed in  claim 1  wherein the device is self-locking when an explosive is detonated, in that high-pressure gasses exert a force on the head section of the actuation member in order to longitudinally displace the head section, so as to further manipulate the expandable sleeve towards the circumferentially expanded position. 
   
   
       20 . A method of plugging an open end of a blasting hole, the method comprising the steps of:
 inserting in the hole a tamping device as claimed in  claim 1 ;   manually manipulating the actuation member in a longitudinal direction to manipulate the expandable sleeve towards the circumferentially expanded position; and   utilizing pressure caused by a blast in the hole to drive the head section of the actuation member further in a longitudinal direction and the sleeve further to the circumferentially expanded position.