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).

Description

FIELD OF THE INVENTION[0001]The present invention relates to a drilling unit and method for slot drilling and a slotting device. In the slot drilling a plurality of holes are drilled closely together so as to form a slot in a rock material. A slot may be formed in a rock surface or into rock mass by drilling a plurality of holes in the surface at a pitch substantially equal to the diameter of the holes. In the slot drilling a special slotting device is needed for guiding the drilling tool along a previously drilled hole. The object of the invention is disclosed more closely in the preambles of the independent claims.BACKGROUND OF THE INVENTION[0002]Slot drilling is a method used in underground and surface mining. In the slot drilling holes are successively drilled very close to each other and when a new hole is drilled next to a previously drilled hole, the wall of rock between the holes is broken. In this manner, a continuous slot is formed by the holes as they are successively dri...

AI Technical Summary

Benefits of technology

[0012]An advantage of the invention is that in normal drilling situation there is an axial gap in drilling direction between the mechanical counter surfaces of the tool and the body of the slotting device, whereby the energy of the stress waves generated by a percussion device are not transmitted to the body and to the guide of the slotting device. Thanks to this, stress waves do not damage the structure of the slotting device and the operating life of the slotting device may longer.

[0013]It is the idea of an embodiment that 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. This being so, the slotting device can be easily connected and disconnected to a standard rock drilling machine according to the need. When the slotting device is disconnected, the rock drilling machine can be used in drilling normal single holes.

[0014]It is the idea of an embodiment that fluid is provided to flush drilling waste from a hole being drilled. Preferably, the fluid flows through an axial volume chamber that is defined between a body portion of a slotting device and the tool, and the flushing fluid damps transmission to the slotting device of impact stress waves generated by a percussion device.

[0015]It is the idea of an embodiment that the slotting device is capable of dislodging itself in the event the slotting device becomes jammed in the slot.

[0016]It is the idea of an embodiment that the slotting device provides valve means regulating a flow of fluid through the axial volume chamber. The valve means restricts the fluid flow thereby increasing fluid pressure and providing additional force to move the slotting device if it becomes jammed.

[0017]It is the idea of an embodiment that the guide portion comprises a tube that is spaced from and parallel to the body portion. Further the tube may comprise a cutout in which an edge of the bit may rotate. This eliminates the risk that the drill bit comes in contact with the tube.

Problems solved by technology

One disadvantage of the disclosed slotting device is that stress waves generated by a percussion device of the drilling machine are transmitted not only to a tool but also to the body structure and to the guide tube.

The stress waves may cause serious damages to the body and the guide of the slotting device.

This said disadvantage concerns especially top hammer applications.

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