Rotary drill
A rotary drill is a drill, which in the mining underground , in open cast mining and tunneling is used for rotary drilling. Rotary drills are mainly used for drilling softer minerals , but they can also work on harder rocks . However, this requires a higher pressing force.
history
The first rotary drilling machine was used by Henning Hutmann in mines in 1636 to drill holes for the blasting work . The first rotating hand drill to be used operationally was the Lisbeth machine. This machine was designed for drilling in softer materials such as coal and rock salt . Other machines of this type were the Lochsche drill used on the Queen Louisengrube in Zabre and the machine from Stanek and Reska. In 1857, the Geneva watchmaker Georges Auguste Leschot introduced diamond rotary drilling. Leschot had constructed a machine in which a crown drill set with a black diamond was set in rotation by means of a gear. The machine was used on a trial basis in the Mont-Cenis tunnel that same year . In the second half of the 19th century, various rotary drilling machines were developed that were equipped with mechanical drives. The hydraulic rotary drilling machine was developed by Alfred Brandt from 1873 to 1877 , in which the drill bits were pressed into the rock with a water pressure of 50 to 200 bar while rotating. Adjustable feed machines have also been developed and used in mining.
construction
Hand-operated machines
The first rotary drilling machines were constructed very simply and were set in rotary motion manually. The Liesbeth machine consisted of a frame in which a fixed screw nut was located. A screw spindle was rotatably inserted into the nut. There was an auger bit at the top of the screw spindle. Other hand-operated rotary drills were constructed similarly. All of these machines had a hand crank for the drive. Such machines are no longer used today.
Mechanically driven machines
In the case of machine-driven machines, a distinction is made between hand-held rotary drills and column-type rotary drills. The machines consist of a housing in which the machine's drive is installed. There are also machine types in which the individual drive components are mounted separately on a base frame. The drive consists of a motor and the gearbox. To protect the machine from overload, the machine has an overload slip clutch . Additional machine components are the drill head spindle, the drill spindle and the spindle gear. A switch lever is used to operate the machine.
equipment
There are different accessories for using the rotary drill. In order to be able to handle the machine better, clamping columns are used. Even with the hand-operated machines, there were simple constructions made of wood, which could be braced against the rock by means of a rotary spindle and thus served as a fixed abutment. These constructions have been continuously developed and improved. The rotary drill is screwed tight to the clamping column. The clamping column is used to absorb the torque generated and to guide the rotary drill. Instead of using a drilling column, the machine can also be used on a drilling carriage with the aid of a drilling carriage . Different drill rods and drill bits are used depending on the rock to be processed. In order to advance the boring bar, a feed gear is required; this is integrated into the machine on smaller hand drills. Larger machines have a separate feed gear.
Drive and feed
The manually driven rotary drilling machines are driven and fed manually. The crank of the machine was turned by hand and the drill was set in rotation. For the feed, the miner had to lean against a rotating chest plate and thus exert pressure on the machine with his body weight. In machine-driven machines, the drive is electric , pneumatic or hydraulic . For the hard coal mining , drives by means of compressed air motors are used due to the required firedamp protection . Rotary drilling machines with electric motors are mainly used in potash and salt mining. There are also machines equipped with diesel engines for opencast mining . In the case of hydraulically driven rotary drilling machines, a liquid with an input pressure of 350 bar is pressed into the drive to drive the machine. The liquids used are emulsions made from water and oil, pure water or hydraulic oil. The power of the motors used is between three and 7.5 kW for electric motors . With diesel engine drives, the output is between 10.3 and 13.3 kilowatts. In machine-operated hand lathes, the feed is carried out manually by pressing the body against the machine. Drill supports are used to improve the feed force. In the case of larger machine-driven rotary drilling machines, the feed is hydraulic.
Individual evidence
- ^ A b c Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
- ↑ a b c d e f g h Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
- ↑ a b c d F.M. Feldhaus: The technology of prehistoric times, historical times and indigenous peoples. Published by Wilhelm Engelmann, Leipzig and Berlin 1914.
- ↑ a b c d e f g Fritz Heise, Fritz Herbst: Textbook of mining studies with a special focus on hard coal mining. First volume, fifth improved edition, published by Julius Springer, Berlin 1923.
- ↑ a b c d Gustav Köhler: Textbook of mining science. 6th improved edition, published by Wilhelm Engelmann, Leipzig 1903.
- ↑ a b c Horst Roschlau, Wolfram Heintze: Bergmaschinentechnik. VEB German publishing house for basic industry, Leipzig 1977
- ↑ a b c d e f Horst Roschlau, Wolfram Heinze, SDAG Wismut (Hrsg.): Knowledge storage mining technology. 1st edition. German publishing house for basic industry, Leipzig 1974.
- ↑ a b c d Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 .