Connector arrangement, drilling arrangement and method for high voltage electro pulse drilling

Abstract

A connector arrangement, drilling arrangement and method for high voltage electro pulse drilling of rock. The connector arrangement (Ca) comprises a high voltage joint (Cj) for connecting high voltage conductors (7, 7a, 7b) and being surrounded by a ground conductor (9). There are flushing channels (11) between the joint and the ground conductor for allowing passage of flushing fluid (F).

1 . A connector arrangement for electro pulse rock drilling, wherein drill holes are formed by means of high-voltage electro pulses conveyed through rock material, the arrangement comprising:
 at least one high voltage conductor joint made of dielectric material and provided with electrical connecting surfaces between two high voltage conductors being connected;   the high voltage conductor joint being surrounded by at least one tubular ground conductor made of metallic material;   between the high voltage conductor joint and the tubular ground conductor is being at least one flushing fluid channel arranged to allow flushing fluid to pass the high voltage conductor joint; and   the high voltage conductor joint including at least one fluid channel between its outer surface and the connecting surfaces, whereby the connecting surfaces are arranged to be surrounded by the flushing fluid.   
     
     
         2 . The connector arrangement as claimed in  claim 1 , wherein the high voltage conductor joint includes at least one centering element supported against inner surfaces of the ground conductor so that the electrical connecting surfaces of the high voltage conductor joint are centered on a central axis of the ground conductor. 
     
     
         3 . The connector arrangement as claimed in  claim 1 , wherein the ground conductor is a drill tube. 
     
     
         4 . The connector arrangement as claimed in  claim 1 , wherein the ground conductor is an intermediate joint element mountable between opposing ends of two successive drill tubes. 
     
     
         5 . The connector arrangement as claimed in  claim 2 , wherein the at least one centering element is an inseparable structural part of the high voltage conductor joint. 
     
     
         6 . The connector arrangement as claimed in  claim 1 , wherein the high voltage conductor joint includes at least one axial groove on its outer periphery facing towards an inner periphery of the ground conductor, whereby the at least one axial groove serves as the at least one flushing fluid channel. 
     
     
         7 . The connector arrangement as claimed in  claim 1 , wherein the high voltage conductor joint comprises:
 an elongated male element made of dielectric material and including a first contact surface at a first end part; and   an elongated female element made of dielectric material and including an axial connecting space arranged for receiving the male element at least partly, wherein a bottom of the axial connecting space is provided with a second contact surface compatible to be connected to the mentioned first contact surface, and wherein the centering elements are integrated on outer surfaces of both the male element and the female element.   
     
     
         8 . A drilling arrangement for high voltage electro pulse rock drilling, the arrangement comprising:
 a drilling tool including at least one drill tube and a drill head connected to a distal end of the drill tube;   a feed device arranged for feeding the drilling tool in a drilling direction and in a return direction;   a flushing device arranged for feeding flushing fluid to the drill head;   a pulse generator arranged for generating high voltage electrical pulses;   first conductors arranged for conducting the generated high voltage electrical pulses to at least one high voltage electrode which is located on a face surface of the drill head;   second conductors arranged for providing a ground potential for at least one ground electrode which is located on the face surface of the drill head, wherein high voltage electrical pulses are transmitted from the high voltage electrode to the ground electrode via the rock material thereby breaking the rock material,   the second conductor including the at least one drill tube which is configured to serve as a ground conductor; and   the first conductor including a high voltage supply conductor arrangement disposed inside the at least one drill tube and being provided with at least a first high voltage conductor and a second high voltage conductor which are connected to each other by means of a connector arrangement in accordance with  claim 1 .   
     
     
         9 . The drilling arrangement as claimed in  claim 8 , wherein the pulse generator is located outside the drilled hole. 
     
     
         10 . A method for electro pulse drilling of rock, the method comprising:
 generating high voltage electrical pulses by means of at least one pulse generator ( 6 );   executing the drilling by means of a drilling tool including at least one drill tube and a drill head connected to a distal end of the drill tube;   feeding the drilling tool in a drilling direction during the drilling;   feeding flushing fluid to the drill head for flushing removed rock material;   conducting the generated high voltage electrical pulses to at least one high voltage electrode on the drill head;   providing ground potential for at least one ground electrode on the drill head;   breaking the rock by transmitting the high voltage electrical pulses from the high voltage electrode to the ground electrode via the rock material;   generating the high voltage electrical pulses outside a drill hole to be drilled;   providing the ground potential via at least one drill tube;   conducting the generated high voltage electrical pulses inside the at least one drill tube by means of at least two high voltage supply conductors and a high voltage conductor joint between the conductors; and   allowing flow of the flushing fluid to pass the high voltage conductor joint;   using liquiform flushing fluid; and   flushing opposite electrical connecting surfaces of the high voltage conductor joint by means of the liquiform flushing fluid for removing gas molecules.   
     
     
         11 . The method as claimed in  claim 10 , further comprising:
 arranging the high voltage conductor joint at a mechanical joint located between two successive drill tubes; and   joining the high voltage conductor joint and the mechanical joint simultaneously when adding drill tubes to the drilling tool.   
     
     
         12 . The method as claimed in  claim 10 or 11 , further comprising allowing a distance between the pulse generator and the drill head to be several meters during the drilling. 
     
     
         13 . The method as claimed in  any one of the preceding claims 10-12 , further comprising drilling a small diameter drill hole being one of the following: blast hole, exploration hole, rock bolt hole, injection hole.