Cutting machine
A cutting machine , also Schräme called, is a device in the mining and quarrying, which for generating a Schram used. There are different working cutting machines, which are divided into hitting, pushing and milling machines.
history
The first suggestions for the development of a cutting machine come from Michael Menzies as early as 1761. In 1862, a cutting machine powered by compressed air was put into operation at the West Ardslay coal mine near Leeds . The cutting machine was further developed in the 19th century by Otto Lilienthal at the Zauckerode Royal Coal Works . His brother Gustav applied for two patents "on improvements to cutting machines with knife discs", which were granted in 1877 for a period of five years. In this way, legal disputes with the Hoppe company, which claimed similar patents in Prussia, were avoided. The original Lilienthal cutting machine was powered by hand. However, the hand-operated cutting machines could not establish themselves permanently. The cutting machine was introduced in the German hard coal mining industry around 1900. In 1906, 10,212 cutting machines were in operation in the United States of America, and 1,136 cutting machines were in operation in Great Britain in the same year.
Percussion cutting machines
Several types were developed of the striking cutting machines, which were similar in their function. The mechanics of the machine were driven by a compressed air motor . The first machine to work on this principle was the Firth and Dennistope machine. A kind of wedge pick was moved via a rod . This machine was constructed in such a way that it mimicked the same sequence of movements as the miners carried out when cutting with a wedge hoe. The engine of this machine was on a wagon made of angle iron . The car was 1.25 meters long, 0.785 meters wide and one meter high. It was moved back and forth on a rail track between the face and the last row of punches at a distance of one meter in front of the face. The engine's piston had a diameter of 131 millimeters and a stroke of 314 millimeters. The wedge pick was made entirely of iron and had a cutting width of 39 to 52 millimeters. There were single and double-clawed wedges. In the optimal case, the machine could perform 70 beats per minute. The wedge pick was able to carve out 26 to 39 millimeters with each stroke. To create a one meter deep scrape, she needed three passes. The machine was able to dig under up to 105 meters of seam in an eight-hour shift . The disadvantage of this machine was that the carriage often jumped out of the rails due to the violent kickback from the piston. The cutting results were also not very good, as the multiple passes during cutting caused bits of coal to fall and narrow the cut. The machine was also very prone to repairs and consumed a lot of compressed air.
On the basis of these machines, other types were developed that had some improvements but also had other shortcomings. The Grafton Jones scraper machine was unable to machine the outer corners of the slot so that the slot was shaped like a segment of a circle. A machine from Maschinenfabrik Hoppe was equipped with two picks, with each pick working a separate area of the scraper. One of the picks had a blade width of 30 millimeters, the other 70 millimeters. Since both picks alternately worked the seam in such a way that when one pecked the other snapped back, the undercarriage remained relatively calm. Another machine was the Frankesche cutting machine. It was much smaller, weighed only 4.5 kilograms and had no base. The stroke of the piston on this machine was only 11 millimeters. The machine was manually moved back and forth in the Schram by a miner. A round steel bar with a flat chisel was used as the cutting tool. The machine was able to prove itself well in the Mansfeld copper slate mining, but it was not usable in the hard coal mining. Overall, the impact cutting machines did not prove themselves in operation.
Scraping machine
A scraper drill is a drill that can be used to turn up to ten drills at the same time. The mechanics of the machine including the drill are on a table. The table is mounted on an undercarriage and can be moved back and forth sideways. This construction is similar to the support on a lathe. The entire apparatus is driven by a compressed air motor with three cylinders . The machine can be used to drill holes in the mineral at a certain height next to each other at short intervals. When a set of holes has been drilled, the drill bits are withdrawn and the table is moved to the side with a lever so that when drilling is repeated, a wall thickness of ten millimeters remains between the individual drill holes. In the areas that cannot be reached with the construction, the holes must be made with a simple drill. The remaining material that remains can easily be broken off so that you get a scratch.
Butt cutting machines
In terms of structure and mode of operation, impact cutting machines are very similar to impact drilling machines. In fact, the same machines were often used for cutting as for drilling. However, the machines were moved back and forth, so that there was no round hole, but an elongated scratch. Mobile machines that could be swiveled on columns were built.
Mobile cutting machines
The first impact cutting machines did not get beyond the experimental stage. The reason for this was their design. Since the machines were operated with compressed air, they were very large and unwieldy. Pneumatic drives were not very suitable because of the compressibility of air. Motors powered by water pressure were better suited. Carratt Mashall & Company in Leeds developed a machine that had a water column as its drive. This was attached to an iron wagon that stood on a track and moved forward with a chain . The chain was designed as an endless chain and driven by the machine by means of a chain star. The redirection took place at the end of the rail. The machine could be moved back and forth on the track using a reverse function. However, the machine failed to perform well in operation because of the high water consumption of five cubic feet per minute.
The basic structure of the Schram cutting machine was the same as the Schram drill. A chasing iron was used instead of the drill. The cutting iron had teeth. The machine was operated with a compressed air motor and was movably mounted on a carriage frame. Since the undercarriage was easy to move, no tracks were required. On inclines, the car was pulled with a reel . The machine was mounted on the cart in such a way that it could hit the mineral to be cut at a certain angle. The machine was moved sideways by means of a threaded rod with a crank. The chisel was also moved forward by means of a threaded rod with a crank. The dust produced during the cutting process was blown away with compressed air. The frame of the machine was braced against the sole and roof with threaded rods . The machine made 400 to 500 strokes per minute, and the machine could undercut an area of up to 156 square meters in 10 hours.
Pillar cutting machines
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One of the first column cutting machines was the Eisenbeis cutting machine. This machine was developed by the mine fitter Eisenbeis from Saarbrücken. The principle of cutting using column machines was already known from the USA. For the Eisenbeissche shearer an impact drill with Schrämstangen and was Schrämkrone a clamp column and a guide sector supplemented with rotating piece. On the erected tensioning column, the guide sector was attached to a slidable clip that was located on the column. The machine was moved forward and swiveled with a separate crank. In order to cut deep enough, the cutting rod had to be exchanged for a longer rod several times during the cutting process. Due to the special connection between the machine and the column, this column cutting machine could be used to create slots at different heights and at any angle. The prerequisite was that the guide sector was always attached to the drilling column parallel to the scraping that was being created. Two miners were required to set up and dismantle the machine, and only one miner to operate the machine. Due to the experience with the Eisenbeis cutting machine, it was later also possible to convert all butting drilling machines into cutting machines. With a column cutting machine, a scraper four to five meters wide can be created without moving the machine. The depth of the Schrams is two to three meters. A trained scraper can cut between twelve and fifteen square meters in an eight-hour shift, and top performance was even twenty square meters. Pillar cutting machines have proven themselves particularly in driving up the road .
Milling cutting machines
In the case of milling cutting machines, a distinction is made between machines with cutting wheels and machines with cutting chains . In the German mining industry, the milling cutting machines were only moderately successful due to the mountainous conditions.
Machines with cutting wheel
In this type of machine, a toothed wheel, which has the height of the desired step, is used as the cutting unit. The way it works, this machine resembles a large circular saw. The milling wheel is mounted on the so-called butterfly, a large iron plate. The butterfly is attached to the frame of the machine. The mechanics are driven by a compressed air motor with two pistons. The cylinders of the engine are mounted offset against each other on a carriage. The motor drives a gear, which in turn drives the milling wheel. The machine's undercarriage is parked on a track, and the machine pulls itself on with a cable. The rope is wound onto a rope drum mounted on the carriage. The machines weigh between 1.5 and 2.5 tons, depending on their size. The cutting wheel has a diameter of 1.6 meters, but the wheel can only create a cutting depth of 1.25 meters. A project to build a cutting machine was started by the Turley company in the Mansfeld mining industry, but it was not completed.
Machines with a cutting chain
With this type of machine, a distinction is made between fixed and movable machines. The fixed machines have a rectangular main frame. This main frame is set up with its longitudinal axis perpendicular to the joint. The distance to the joint is kept very small. The entire frame is secured against displacement with several struts. A second frame is movably mounted on slide rails in the main frame. The horizontal movement of the inner frame on the rails is done by means of a rack. Around the entire circumference of the inner frame is the cutting chain, which is guided over chain stars. There is an air motor on the rear end of the frame. This ensures, on the one hand, that the cutting chain is driven and, on the other hand, that the inner frame moves forward. There are several control levers for controlling the machine. When the machine is started, the chain moves at a speed of 1.3 to 1.5 meters per second, creating a scratch with a height of eleven to thirteen centimeters. Once the specified scratch depth has been reached, the control lever is switched and the machine moves the inner frame back to its starting position. So that the machine can be moved sideways, the struts must be loosened and then fastened again. The machine took about six to seven minutes to cut in, and it took two to three minutes to move it sideways. These machines could undercut eleven to fourteen square meters per hour. Due to their weight, they were only suitable for flat storage . They also required a lot of space due to their size. For the cutting work in the face there were movable chain cutting machines, which were very similar in structure to the machines with cutting wheels. These machines were powered by an electric motor.
Modifications
In the first half of the 20th century, the chain cutting machines were improved. These machines consisted of a cutter head, the feed winch and the drive motor. A swiveling cutting arm around which the cutting chain runs is attached to the cutting head. In the cutting head there is a gear and the mechanical swivel devices for the swivel arm. The swivel arm can be swiveled mechanically with a hydraulic gear or manually with a ratchet. Compressed air motors with an output of 55 kilowatts and a compressed air consumption of up to 3000 cubic meters per hour or firedamp-proof squirrel cage motors with outputs of up to 80 kilowatts were used as drive motors. The crowd winch is required to pull the cutting machine along the joint. The winch is protected against overload and stops when it is overloaded. Machines with double booms were also designed and used. These had two swivel arms arranged one above the other. The distance between the swivel arms was adjustable between 500 and 1000 millimeters so that the machine could be adapted to the respective conditions on site. Both swivel arms were coupled to one another and could be swiveled in or out together manually or mechanically. There were also machines that could create both a scratch and a notch. These machines consisted of a vertical guide frame and a horizontal guide frame formed from three tubes. The actual cutting machine was located on the horizontal guide frame. The entire machine was moved by a crawler track. The machine's drive motor had an output of 20 kilowatts. The machine was able to create slots 90 millimeters thick.
commitment
In the mining industry, cutting machines were used to create one or more inclined slots in the mineral to be extracted or in the coal seam . In this way, the coal could be broken out more easily with a hoe or other equipment. The shearer loader is the further development of a combination of a shearer / shear roller, which separates the excavated material from the seam , and a cross scraper to clear away the excavated material, e.g. B. on a double chain conveyor , so that extraction and loading are carried out fully mechanically.
In quarries , whole blocks are cut out of the wall with cutting machines. The working depth of the Schräme in the quarry is approx. 2.50 m. The saw chain has chain links that are made of either hard metal or hard metal with diamond inlays. Schrämen saw only in soft stone (marble, soft limestone, clay-bonded sand stones and tuffs).
literature
- Steffen, v. Praun: The practical miner , 4th edition, Lehrmitteldienst GmbH, Hagen / Essen 1954
Individual evidence
- ^ 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 i Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, published by Julius Springer, Berlin 1908.
- ↑ a b c d e f g h i j Albert Serlo: Guide to mining science. First volume, published by Julius Springer, Berlin 1869.
- ^ Panel with inscription in the Otto Lilienthal Museum - Liepen / Anklam. (accessed September 5, 2011).
- ↑ Ernst-Ulrich Reuther: Introduction to mining. 1st edition, Verlag Glückauf GmbH, Essen, 1982, ISBN 3-7739-0390-1 .
- ^ Lexicon of all technology, cutting machine (accessed on September 5, 2011).
- ↑ a b c d e Gustav Köhler: Textbook of mining science. 2nd edition, published by Wilhelm Engelmann, Leipzig 1887.
- ^ Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
- ↑ Heinz Kundel: coal mining. 6th edition, Verlag Glückauf GmbH, Essen, 1983, ISBN 3-7739-0389-8 .
- ↑ Chain cutter for making slits in solid rock. Patent No. DE19625039C2 June 10, 1998 (accessed September 6, 2011).
