Drilling unit, method for slot drilling and slotting device

Abstract

A slotting device ( 100 ) to be used with a rock drilling apparatus ( 1 ) to drill closely together a plurality of parallel intersecting holes so as to form a slot in a brittle material, such as rock, masonry or concrete. The slotting device ( 100 ) includes a guide portion ( 110 ) connected to a body portion ( 120 ) with at least one strut ( 130 ). The guide portion ( 110 ) is disposed in a previously drilled hole, and the body portion ( 120 ) and a rotary percussion tool ( 7 ) mutually define a variable volume chamber ( 140 ) that contains flushing fluid that damps transmission of impact stress waves from a percussion device ( 4 ) of the drilling apparatus ( 1 ) to the slotting device ( 100 ).

1 . A rock drilling unit for slot drilling, comprising
 a feed beam,   a rock drilling machine arranged on the feed beam, and comprising a percussion device and a flushing device,   a tool connected to the rock drilling machine,   and wherein the percussion device is arranged to produce impact stress waves directed to the tool, and the flushing device is arranged to supply flushing fluid through the tool for flushing drilling waste from a hole being drilled,   a feeding device, which is arranged to move the drilling machine on the feed beam and to feed the tool in the hole being drilled,   a slotting device connected to the rock drilling machine and comprising a guide portion, a body portion and at least one strut extending between and coupling the guide portion and body portion, and wherein the guide portion is disposed in a previously drilled hole, and wherein the tool is arranged slidingly through the body portion,   and between the body portion of the slotting device and the tool there is at lest one axial volume chamber containing fluid so as to dampen transmission of the impact stress waves from the percussion device to the slotting device.   
     
     
         2 . The rock drilling unit according to  claim 1 , wherein
 the axial volume chamber is connected to the flushing device by means of at least one flow channel, and   the axial volume chamber contains flushing fluid.   
     
     
         3 . The rock drilling unit according to  claim 1 , wherein
 the slotting device is a dismountable auxiliary device connected to a shank of the rock drilling machine or to a drill rod connected to the shank.   
     
     
         4 . The rock drilling unit according to  claim 1 , wherein
 the body portion of the slotting device and the tool mutually define the at least one axial volume chamber containing fluid.   
     
     
         5 . The rock drilling unit according to  claim 1 , wherein
 the body portion of the slotting device and the tool mutually define the at least one axial volume chamber containing fluid,   the body portion of the slotting device comprises a sleeve including a bore through which the tool extends,   the bore of the sleeve comprises a first diameter portion, a second diameter portion smaller than the first diameter portion, and a shoulder portion extending between and coupling the first diameter portion and second diameter portion,   the first diameter portion of the bore slidingly receives a piston portion of the tool, and the second diameter portion of the bore receives a rod portion of the tool,   the axial volume chamber comprises an annulus that is defined radially between the first diameter portion of the bore and the rod portion of the tool, and is defined axially between the piston portion of the tool and the shoulder portion of the bore,   the slotting device further comprises a flow passage supplying the flushing fluid along the tool, the flow passage comprises an axial flow passage disposed radially between the rod portion of the tool and the second diameter portion of the bore, a first generally radial flow passage connecting a first internal passageway of the tool to a first axial end of the axial flow passage, and a second generally radial flow passage connecting a second internal passageway of the tool to a second axial end of the axial flow passage,   the bore of the sleeve comprises a third diameter portion smaller than the second diameter portion, the third diameter portion slidingly receives the rod portion of the tool, and   relative axial displacement of the tool with respect to the body portion restricts fluid flow through the second generally radial flow passage and increases fluid pressure moving the body portion with respect to the tool.   
     
     
         6 . The rock drilling unit according to  claim 1 , wherein
 between the tool and the body portion there is a dampening piston, which is in axial connection to the body portion and is in the axial direction separated by means of fluid from the tool.   
     
     
         7 . The rock drilling unit according to claim  claim 1 , wherein
 between the tool and the body portion there is a dampening piston, which is in axial connection to the body portion and is in the axial direction separated by means of fluid from the tool,   the body portion of the slotting device comprises a sleeve including a bore through which the tool extends,   the tool comprises a flow passage that extends through it,   the dampening piston comprises an interior portion arranged within the flow passage, an exterior portion around the tool and at least one coupling portion coupling the interior portion and exterior portion together,   the piston is arranged slidingly movably with respect to the tool,   the interior portion comprises a first working pressure surface affecting towards the drilling direction and a second working pressure surface affecting towards the reverse direction,   a first axial volume chamber is on the first working pressure surface side of the piston and the fluid therein is transmitting the feed force from the tool via the piston to the sleeve, and   a second axial volume chamber is on the second working pressure surface side of the piston and the fluid therein prevents mechanical axial contact between the tool and the piston in the drilling direction.   
     
     
         8 . The rock drilling unit according to  claim 1 , wherein
 between the tool and the body portion there is a dampening piston, which is in axial connection to the body portion and is in the axial direction separated by means of fluid from the tool,   the body portion of the slotting device comprises a sleeve including a bore through which the tool extends,   the tool comprises a flow passage that extends through it,   the dampening piston comprises an interior portion arranged within the flow passage, an exterior portion around the tool and at least one coupling portion coupling the interior portion and exterior portion together,   the piston is arranged slidingly movably with respect to the tool,   the interior portion comprises a first working pressure surface affecting towards the drilling direction and a second working pressure surface affecting towards the reverse direction,   a first axial volume chamber is on the first working pressure surface side of the piston and the fluid therein is transmitting the feed force from the tool via the piston to the sleeve,   a second axial volume chamber is on the second working pressure surface side of the piston and the fluid therein prevents mechanical axial contact between the tool and the piston in the drilling direction,   the flow passage of the tool comprises at least one axial flow passage, which connects the axial volume chambers,   and wherein an axial movement of the piston relative to the tool in the reverse direction is arranged to restrict the pressure of the fluid affecting the first working pressure surface thus increasing the feed force transmitted via the piston to the sleeve.   
     
     
         9 . The rock drilling unit according to  claim 1 , wherein
 the guide portion comprises at least one elongated guiding flange extending longitudinally along a peripheral surface of the guide portion.   
     
     
         10 . The rock drilling unit according to  claim 1 , wherein
 the feed beam is provided with a hold device at the distal end of the feed beam, and   the hold device comprises an opening, which is dimensioned according to a cross sectional profile of the slotting device allowing the slotting device to be pushed through the hold device.   
     
     
         11 . A slotting device comprising:
 an elongated tool including a first end and a second end, and wherein the first end is provided with first coupling means for attaching the slotting device to a shank of a drilling machine or to a drill rod connected to the shank, and wherein the second end is provided with a drill bit,   a body portion through which the tool is arranged,   a guide portion disposable in a previously drilled hole, and   at least one strut extending between and coupling the guide portion and body portion,   and the slotting device is provided with at least one axial volume chamber between the body portion and the tool, and   wherein the slotting device comprises at least one flow channel for directing fluid into the chamber, whereby the fluid in the chamber is arranged to transmit axial forces from the tool to the body portion.   
     
     
         12 . The slotting device according to  claim 11 , wherein
 the slotting device comprises at least one feed channel for feeding flushing fluid from the rock drilling machine into the axial volume chamber and at least one discharge channel for discharging flushing fluid from the axial volume chamber to the hole being drilled, whereby flushing fluid is arranged to flow through the axial volume chamber.   
     
     
         13 . The slotting device according to  claim 11 , wherein
 the slotting device comprises means for monitoring axial forces opposing the disposal of the guide portion into the previously drilled hole,   and means for increasing pressure of the fluid affecting in drilling direction on at least one working pressure surface of the at least one axial volume chamber as a response to the monitored opposing forces, whereby axial force transmitted to the guide portion is increased.   
     
     
         14 . The slotting device according to  claim 11 , wherein
 the slotting device comprises valve means for affecting the volume flow through the axial volume chamber as a response to the relative axial position of the tool and the body portion.   
     
     
         15 . A method for slot drilling, comprising:
 drilling closely together a plurality of holes so as to form a slot in a rock material,   using in drilling a rock drilling machine comprising a percussion device for generating percussion pulses to a tool connected to a rock drilling machine,   connecting a slotting device to the rock drilling machine, the slotting device comprising: a body portion through which the tool is arranged, a guide portion, and at least one strut extending between and coupling the guide portion and body portion,   disposing a guide portion in a previously drilled hole for maintaining the course of the previously drilled hole for the new hole being drilled, and   transmitting during drilling a feed force towards the drilling direction from the tool to the body portion of the slotting device and further to the guide portion,   transmitting the feed force to the body portion of the slotting device in the drilling direction by means of fluid in at least one axial volume chamber between the tool and the body portion, and   dampening transmission of the impact stress waves from the percussion device to the slotting device by means of the fluid in the at least one axial volume chamber.   
     
     
         16 . A method as claimed in  claim 15 , comprising
 influencing pressure of the fluid in the axial volume chamber in response to the axial movement between the body portion and the tool arranged to slide longitudinally relative to each other.   
     
     
         17 . A method as claimed in  claim 15 , comprising
 influencing pressure of the fluid in the axial volume chamber in response to the axial movement between the body portion and the tool arranged to slide longitudinally relative to each other,   arranging fluid flow through the axial volume chamber, and   restricting the fluid flow through the axial volume chamber when the movement of the guide portion in the previously drilled hole is hindered, whereby the feed force transmitted to the guide portion is increased.   
     
     
         18 . A method as claimed in  claim 15 , comprising
 influencing pressure of the fluid in the axial volume chamber in response to the axial movement between the body portion and the tool arranged to slide longitudinally relative to each other,   arranging fluid flow through the axial volume chamber,   restricting the fluid flow through the axial volume chamber when the movement of the guide portion in the previously drilled hole is hindered, whereby the feed force transmitted to the guide portion is increased   arranging fluid flow through the axial volume chamber,   closing the discharge fluid flow through the axial volume chamber when the movement of the guide portion in the previously drilled hole is stopped, whereby the pressure of the fluid in the axial volume chamber increases,   monitoring the pressure of the fluid affecting in the axial volume chamber, and   reversing the feed movement of the rock drilling machine when the pressure of the fluid in the axial volume chamber exceeds a predetermined pressure limit.   
     
     
         19 . A method as claimed in  claim 15 , comprising
 connecting at least one drill rod to a shank of the drilling machine, and   connecting the slotting device to a distal end of an outermost drill rod.   
     
     
         20 . A method as claimed in  claim 15 , comprising
 connecting the slotting device to a shank of the drilling machine.   
     
     
         21 . A method as claimed in  claim 15 , comprising
 supporting the guide portion to surfaces of the previously drilled hole by means of at least one elongated guiding flange extending longitudinally along a peripheral surface of the guide portion.   
     
     
         22 . A method as claimed in  claim 15 , comprising
 conveying flushing fluid into the axial volume chamber.