EP0321383B1 - Device for detecting the cutting horizon for winning machines - Google Patents

Description

The invention relates to a device for recognizing the cutting horizon for mining machines, such as coal planers and roller loaders, in particular for detecting the position of the coal-rock boundary layer with the aid of light signals of selected wavelengths on reflection surfaces, with at least one sensor head on the mining machine with one lying on the lying surface is provided to the leading lower surface and a transmitting and receiving station are arranged on the machine body, and wherein between the transmitting and receiving station and the sensor head designed as a light transmitter and receiver and guided in a channel of the sensor head bundles of optical fibers are arranged, which channel through a Crystal window is closed, the lower surface of which lies in the plane of the lower surface of the sensor head.

In DE-C-35 09 868 an automatic control for the height-adjustable chisel of a coal plane is described in more detail. The coal-rock boundary layer is detected by means of pulsed light by means of at least one transducer, and the different reflection properties of coal and bedrock are used to control the tools. The measuring probes in the sensor head, which are dragged on the lying surface, are formed by the ends of optical fiber bundles which are connected to a light transmitter and a light receiver. The optical fiber bundles are embedded in a solid ceramic layer in the sensor head and extend to the outer surface of a ceramic body.

Although the tests with respect to the reflection measurements on coal and lying rock, especially using selected wavelengths, brought clearly recognizable and easily differentiable measurements that were sufficient for a corresponding control, the practical tests failed because the test on a test bench was grinding The sensor head embedded in concrete and lying rock and the fiber optic bundles embedded in a ceramic plate were scattered in the laboratory due to wear on the sensor head base and the associated kinking and bending of individual fiber optic fibers, which did not allow clear identification of the important horizon.

A device for detecting the cutting horizon for mining machines, according to the preamble of independent claim 1, is known from the report DE research project "Measuring system for coal planes" interim report for the period from January 1, 1987 to March 31, 1987 for Ruhrkohle AG, Batelle Institute in Frankfurt am Main, 4. 1987 work package 4000 pages 10 and 11. As can be seen from this report, in order to reduce the scatter values resulting from wear of the optical waveguide fibers with a view to better identification, the optical waveguide fibers were sealed with an optical window in the form of a sapphire, this window withstood the mechanical stresses caused by grinding over coal and rock.

However, the use of a crystal window did not lead to any clear results when carrying out tests due to back-reflected radiation components from the entrance and exit surface of the crystal window, since the signals from the direct reflectors from the entrance and exit surface made of sapphire crystal were larger than the measurement signal from coal and Rock under the sapphire crystal.

From DE-U-87 04 679 a measuring device for surfaces with colored gloss effects is known, the measuring head having an illuminating device and three radiation sensors separate from the illuminating device. The transducers are arranged at a different angle from the lighting device and each The sensor is arranged at a different angle to the regularly reflected radiation.

The invention has for its object to provide a device for recognizing the cutting horizon for mining machines such as coal planer and shearer loader, which enables a clear identification of the coal-rock boundary layer due to the radiation components that get from coal and rock into the receiving fibers.

According to the invention, this object is achieved in that the channel receiving the optical waveguide bundles extends at an angle of 20 to 45, preferably 30, degrees to the lower surface of the crystal window in the outlet of the sensor head.

Due to the spectral behavior of coal and bedrock, a calculated ratio of the measured values at 850 nm and 1550 nm is achieved and a clear distinction is achieved.

Other wavelength combinations are also conceivable within the scope of the invention. Powerful light sources, namely a light-emitting diode (LED) or a laser diode for the wavelength of 850 nm and a laser diode for the wavelength of 1550 nm, are provided for the selected wavelengths. Another advantage of these wavelengths is that the water represents an optical window for these wavelengths and therefore moisture has no influence on the measurements.

The sapphire selected for the window has the advantage that it is optically transparent in the range of the measuring wavelengths and can be mechanically loaded due to its hardness. The light is transmitted to the patient from the light sources via a two-arm fiber optic bundle. The optical window is located at the end of the optical waveguide bundle facing towards the lying surface. The portions of the transmitted radiation reflected by the person lying down are received again by the individual fibers of the receiving arm. For the guidance of the optical fiber bundles, it proves to be particularly advantageous in the context of the invention that they run over the entire length in a flexible jacket and plug inserts are provided at the ends of the jacket, in which the optical fiber bundles end in the form of eyes. The fiber optic bundles composed of a large number of individual fibers with a diameter of, for example, 70 μ open into two eyes on the upper side of the upper plug-in insert on the transmission side for the wavelengths of 850 nm and 1550 nm to be used, in this plug-in insert another eye for the Receiving arm of the fiber optic bundle is provided. Another particular advantage is the fact that the two wavelengths of 850 and 1550 nm of individual fibers of the optical fiber bundle used as transmitter arms, statistically mixed, bundled into a branch, on the lower side of the plug-in insert lying to form an eye, around which the individual fibers of the receiving arm are arranged concentrically.

The fiber optic bundles sit snugly on the lower side of the lower insert on the inside of the sapphire window. The fiber optic fiber bundle on the side of the multi-gym, with two transmitter arms - one for each wavelength - concentrates on the contact surface to the inside of the sapphire window to form a transmitter arm. The individual fibers of the transmitter arms are statistically mixed in the middle.

The individual fibers of the receiver arm concentrically enclose the transmitter arm. With this arrangement, a more punctiform exit of the transmission radiation and a proportionate uniform reflection radiation of both wavelengths are fed to the receiving arm. In order to keep the proportion of radiation directly reflected by the entry and exit surface of the sapphire crystal relatively small, the outside of the sapphire crystal is ground at an angle of 30 degrees with respect to the inside.

Die Größe des Streupegels ist in erster Linie von der Oberflächengüte des Kristallfensters abhängig. Aus diesem Grunde weist das Kristallfenster auf der das Auge aufnehmenden Seite und der auf dem Liegenden schleifenden Seite jeweils geschliffene und polierte Oberflächen auf. Die erforderliche Sende- und Empfangseinheit ist auf dem Hobelkörper in entsprechenden Freiräumen angebaut. Der Sensorkopf ist in der unteren Führung des sogenannten Wackelkopfes befestigt und über ein Federungssystem auf das Liegende gedrückt. Um die während des Hobelns zwangsläufig auftretenden horizontalen und vertikalen Bewegungen mit dem Sensorkopf ausgleichen zu können, muß dieser auf das Liegende gedrückt werden. Es darf hierbei nicht zu Eigenschwingungen des Sensorkopfes durch die Federn kommen. Aus diesem Grund sind zwischen Sensorkopf und Sensorkopfhalter in Fahrtrichtung nebeneinander mehrere beispielsweise drei Führungsbolzen vorgesehen, die von Vorspannfedern umgeben mit ihren Enden in Bohrungen des Sensorkopfes geführt sind. Die jeweils benötigte Vorspannkraft bzw. Federung ist vom Spiel in der Hobelanlage abhängig, weil sich dadurch die vertikalen und horizontalen Bewegungen des Hobels verändern.Because the entry angle is the same as the exit angle in the optics, the majority of the reflection from the exit side of the sapphire crystal, which is not to be detected, is not detected by the fibers of the receiving arm, but only their diffuse components. Of coal and bedrock however, the same proportion of the transmitted radiation is reflected by both wavelengths and detected by the receiving arm. If the diffuse reflection from the exit and entry surface of the sapphire crystal is used as a constant and the ratio of the desired measurement signal of coal or bedrock at 850 nm and 1550 nm is obtained, the result is an evaluable signal, the ratio value:

The size of the scattering level depends primarily on the surface quality of the crystal window. For this reason, the crystal window has ground and polished surfaces on the side that receives the eye and the side that grinds on the lying surface. The required transmitter and receiver unit is installed on the planer body in appropriate free spaces. The sensor head is fastened in the lower guide of the so-called wobble head and pressed onto the bed using a suspension system. In order to be able to compensate for the horizontal and vertical movements that necessarily occur during planing, the sensor head must be pressed onto the surface. The sensor head must not vibrate naturally due to the springs. For this reason, several, for example, three guide bolts are provided next to each other in the direction of travel between the sensor head and the sensor head holder, the ends of which are guided by prestressing springs in bores in the sensor head. The prestressing force or suspension required depends on the play in the planing system, because this changes the vertical and horizontal movements of the planer.

According to the invention, a measuring insert is interchangeably arranged in the end face of the sensor head and, in addition to the crystal window, also receives the plug-in insert for the optical fiber bundles displaced in a flexible sheathing. The measuring insert is advantageously divided into two and consists of the wear plate guided on the lying surface and the wear plate holder. In this way it is possible to replace the wear plate, which is subject to considerable wear, if necessary. Inside the wear plate holder, the plug insert or the lower end of the casing is fixed in its seat by a specially designed molded flange so that the optical fiber bundle always lies exactly on the inner surface of the crystal window. An O-ring provides a hermetic seal against dust between the contact surface of the eye receiving the optical fiber bundle and the crystal window.

The joint-free sealing surface between the wear plate and the wear plate holder is achieved by the special shape of these parts of the measuring insert. The connecting screws for connecting the two parts of the measuring insert are located at unloaded points on the measuring insert. A comparable connection is also provided for locking the measuring insert in the sensor head.

Another advantage for the functionality of the sensor head can be seen in the fact that clearing shoes which can be detachably connected to the sensor head are articulated on both sides of the sensor head facing the respective direction of travel. These clearing shoes prevent that during the journey between a carbon film is rolled onto the face of the sensor head and the reflective surface, making exact identification of the horizon impossible. The clearing shoes are accommodated in a form-fitting manner in the sensor head and are held by screws which are inserted or screwed inside the recess provided for the measuring insert.

The technical progress of the invention is essentially based on the fact that, based on the reflective properties of coal and rock, it is possible to clearly identify the boundary layer, which is of immense importance in view of the possibility of recording or extracting unnecessary rock layers.

The identification not only concerns the exact determination of the coal / bedrock boundary layer, but could also be used to identify coal and bedrock or stored mining materials.

An embodiment of the invention is shown in the drawings and is explained in more detail below.

Figur 1

eine teilweise und schematisiert wiedergegebene Seitenansicht eines Kohlenhobels in Verbindung mit einem schleifend mitgeführten Sensorkopf

Figur 2

eine Prinzipsskizze der unter einem bestimmten Winkel endenden Lichtwellenleiterbündel in Verbindung mit dem Kristallfenster

Figur 3

eine teilweise geschnittene Wiedergabe eines Sensorkopfes

Figur 4

eine Seitendarstellung des Sensorkopfes in Verbindung mit einem Sensorkopfhalter

Figur 5

eine Seitenansicht des Schleißplattenhalters im Schnitt

Figur 6

eine Seitenansicht der Schleißplatte im Schnitt

Figur 7

eine Draufsicht auf den Schleißplattenhalter

Figur 8

eine Draufsicht auf die Schleißplatte und

Figur 9

ein Diagramm über das Reflektionsverhalten von Kohle/Nebengestein unter Berücksichtigung der ausgewählten Wellenlängen.

Show it:

Figure 1

a partially and schematically reproduced side view of a coal plane in connection with a grinding sensor head

Figure 2

a schematic diagram of the fiber optic bundles ending at a certain angle in connection with the crystal window

Figure 3

a partially cut reproduction of a sensor head

Figure 4

a side view of the sensor head in connection with a sensor head holder

Figure 5

a side view of the wear plate holder in section

Figure 6

a side view of the wear plate in section

Figure 7

a plan view of the wear plate holder

Figure 8

a top view of the wear plate and

Figure 9

a diagram of the reflection behavior of coal / bedrock taking into account the selected wavelengths.

The coal planer 1 shown in FIG. 1 as an exemplary embodiment and only partially shown has a sensor head 3 on one side towards the lying surface 2 in a guide 8 indicated schematically. The sensor head 3 is dragged along the lying surface 2 by means of a spring element 9. The dashed lines surround the transmitting station 10, receiving station 11, power station 12 required on a plane 1 for functionality, and, if necessary, a memory module. All stations are vibration-damped, preferably housed in a common housing, the common housing being additionally dampened on vibrating metals. A common optical fiber bundle 5 in a flexible sheathing leads from the transmitting station 10 or to the receiving station 11 to the sensor head 3. The sensor head 3 grinds with the end face 4 on the lying surface 2. The spring element 9 shown schematically is based on an exemplary embodiment in FIG. 4 described in more detail.

However, as already indicated in FIG. 1 within the sensor head with dashed lines and shown in more detail in principle in FIG. 2, the bundle of optical fibers extends at the exit of the sensor head 3, namely the transmitter arm 5 or receiver arm 5 'in connection with the crystal window 7 at an angle of 30 degrees to the lying position 2. The receiving eye 19, the optical fiber bundle in the form of a transmitter arm 5, in which the individual fibers of the different wavelengths are arranged statistically mixed, takes the optical fiber bundle of the receiving arm 5 'concentrically around the optical fiber bundle of the transmitter arm 5 and lies flat the crystal window 7. The arrows indicated within the crystal window clarify that the essential reflection, which is undesirably caused by the lower surface 13 of the crystal window 7, is deflected to the side and thus only part of the disturbing reflection is received by the receiving arm 5 '. The lower surface 13 of the crystal window 7 lies in the plane of the lower surface or end face 4 of the sensor head 3. FIG. 3 shows a view of the sensor head 3 with a view of the conveying means. The sensor head 3 is shown cut at least in the left half of the picture. In the end face 4 of the sensor head 3, which is guided in a sliding manner on the lying end 2, a recess 24 is provided in which a measuring insert 25 can be detachably inserted. The measuring insert 25 is held by two screws 35 in corresponding bores 36, one screw of which is shown. Inside the sensor head 3, the optical waveguide bundles run within a protected and flexibly designed sheathing 14. Inside the sensor head 3, the sheathing 14 receiving the optical fiber bundles 5, 5 ′ is provided with a plug insert 17 at the lower end 15. The optical fiber bundles 5, 5 ′ end in the plug insert 17, as already mentioned in the basic sketch according to FIG. 2, in one Eye 19. An adapter plug 18 is provided for locking the optical fiber bundles at the kink point 48. The lower plug insert 17 is fastened in a dust-tight manner within the insert 25 by means of a special flange arrangement and with the aid of an O-ring 46.

The measuring insert 25 consists of two parts which can be detachably connected to one another, namely the wear plate 26 and the wear plate holder 27. Before the measuring insert 25 is mounted, broaching shoes 39 can be mounted on the narrow sides of the sensor head 3 in the respective direction of travel. The clearing shoes are fastened with the aid of countersunk screws 40 from the recess 24 for the measuring insert and can be replaced when worn.

The measuring insert 25 is shown in detail in FIGS. 5 to 8. The wear plate 26 of the measuring insert 25 has a flat section 30 and a larger section 31, the two sections 30, 31 being connected to one another via an inclined surface 32. In the inclined surface 32, a bore 33 is provided at an angle of 20 to 45 degrees, but preferably at 30 degrees, which in an expanded form merges into a recess 22 receiving the crystal window 7. The corresponding wear plate holder 27 in the assembled state with the wear plate 26 has a stepped bore 34, the axis of which lies in the axis of the bore 33 within the wear plate 26. As can be seen from the plan views according to FIGS. 8 and 9, the two parts 26, 27 forming the measuring insert 25 are connected to one another by countersunk screws 28 in correspondingly provided bores 29. In this way, the wear plate 26, which is exposed to great wear, can be quickly replaced if necessary.

In principle, the crystal window 7 has the shape shown in FIG. 2 and is glued into the receptacle 22. The crystal window 7 ends before the gradation, which limits the bore 33. The sensor head 3, which is arranged close to the conveying means on the coal planer 1 and guided on the lying end 2, is stepped in cross-section towards the conveying means, as can be seen in FIG. 4 and is provided with a protective plate 38. The sensor head 3 is made of a resistant and low-wear material such as hardened steel and is pressed against the sensor 2 against a sensor head holder 41 by a spring element 9. In the exemplary embodiment shown in FIG. 4, the spring element 9 consists of, for example, three guide bolts 42 arranged next to one another in the direction of travel, of which the middle one is designed as a preload screw, which are surrounded by preload springs 43 and are guided with their ends 44 into bores 45 of the sensor head 3. In contrast to the guide bolts, the preload screw can deflect upwards with the screw head.

The measurement results of the spectral overview measurements are summarized and graphically represented in FIG. It can be seen from this that the secondary rocks reflect significantly more strongly than coal at all colors and wavelengths. Another difference is that the reflection from bedrock increases almost evenly with increasing wavelength. The reflection of coal, on the other hand, remains relatively constant in the visible region of the spectrum and quickly rises to twice the value in the central region. This fact allows a reliable evaluation of the measurement signals.

Claims (20)

1. Apparatus for detecting the cutting horizon for mining machines, such as coal ploughs and roll loaders, in particular for detecting the position of the coal-rock interface with the aid of light signals of selected wavelengths at reflection surfaces, there being provided on the mining machine (1) at least one sensor head (3) having a lower surface (4) adapted to be slidingly guided on the footwall (2) and a transmitting and receiving station (10, 11) are arranged on the machine body, and there being arranged optical waveguide bundles (5, 5') between the transmitter and receiving station (10, 11) and the sensor head (3), said optical waveguide bundles (5, 5') being formed as light transmitting and light receiver and guided in a passage (6) of the sensor head (3), said passage (6) being closed by a crystal window (7) whose lower surface (13) is located in the plane of the lower surface (4) of the sensor head (3), characterized in that the passage (6) receiving the optical waveguide bundles (5, 5') extends in the exit of the sensor head (3) at an angle of 20 to 45, preferably 30 degrees to the lower surface (13) of the crystal window (7).
2. Apparatus according to claim 1, characterized in that the optical waveguide bundles (5, 5') extend within the sensor head (3) in a flexible sheath (14) and at the ends (15, 16) of the sheath (14) plug-type inserts (17, 18) are provided in which the optical waveguide bundles (5, 5') terminate in the form of eyes.
3. Apparatus according to claim 2, characterized in that the optical waveguide bundles (5) made up of a plurality of individual fibres with a diameter of 70 µ terminate in two eyes at the upper side of the upper plug-type insert (18) on the transmitter side for the wavelengths of 850 nm and 1550 nm to be used and a further eye is provided for the optical waveguide bundle (5') of the receiver arm.
4. Apparatus according to claim 2, characterized in that the individual fibres of the optical waveguides (5) used for two wavelengths of 850 nm and 1550 nm as transmitter arms statistically mixed to a branch at the lower side of the plug-type insert (17) directed towards the footwall (2) form an eye about which the individual fibres of the optical waveguide bundle (5') of the receiver arm are concentrically disposed.
5. Apparatus according to claim 1, characterized in that the eye (19, 20) centrally receiving the individually fibres of the optical waveguide bundles (5) of the two wavelengths statistically mixed and the individual fibres of the optical waveguide bundle (5') of the receiver arm concentrically about the optical waveguide bundle (5) bears flush at the lower side of the lower plug-type insert (17) on the inner side (21) of the crystal window (7).
6. Apparatus according to claim 5, characterized in that the crystal window (7) secured for example by means of bonding interchangeably in a recess (22) has ground and polished surfaces on the side (21) receiving the eye (19) and the side (13) sliding on the footwall (2).
7. Apparatus according to claim 3, characterized in that as light sources on the transmitter side for the wavelengths of 850 nm a light-emitting diode (LED) or laser diode is provided and for the wavelength of 1550 nm a laser diode is provided.
8. Apparatus according to claim 7, characterized in that as evaluation signal a mathematical value (ratio value) is provided which is formed by the following quotient

   
9. Apparatus according to claim 1, characterized in that in the end face (4) of the sensor head (3) sliding on the footwall (2) a recess (24) is provided for a measuring insert (25) receiving the lower plug-type insert (17) and the crystal window (7).
10. Apparatus according to claim 9, characterized in that the measuring insert (25) consists of two detachably interconnectable parts of a lower wear plate (26) flush with the end face (4) of the sensor head (3) and a wear plate holder (27) disposed thereabove.
11. Apparatus according to claim 10, characterized in that the wear plate (26) and the wear plate holder (27) are connected together from the top via countersunk screws (28) led through the weld plate holder (27).
12. Apparatus according to claim 10, characterized in that the wear plate (26) of the measuring insert (25) comprises a flat portion (30) and a thicker dimensioned portion (31), the two portions (30, 31) being connected together via an inclined surface (32) in which at an angle of 20 to 45 degrees, preferably 30 degrees, a bore (33) is provided which in stepped manner merges into a recess (22) receiving the crystal window (7).
13. Apparatus according to claim 10, characterized in that the wear plate holder (27) corresponding in the assembled state to the wear plate (26) has a stepped bore (34) of which the axis lies in the axis of the bore (33) in the wear plate (26).
14. Apparatus according to claim 9, characterized in that the two-part measuring insert (25) insertable into the recess (24) is detachably held via screws (35) led through the sensor head (3).
15. Apparatus according to claim 1, characterized in that the sensor head (3) arranged near the conveyor means at the coal plough (1) and sliding on the footwall (2) is reduced in stepped manner in cross-section seen towards the conveyor means.
16. Apparatus according to claim 1, characterized in that the sensor head (3) is provided at both sides disposed in the direction of travel with clearing shoes (39).
17. Apparatus according to claim 16, characterized in that the clearing shoes (39) are detachably connected to the sensor head (3).
18. Apparatus according to claim 16, characterized in that the clearing shoes (39) are secured detachably to the sensor head (3) via screws (40) insertable within a recess (24) in the sensor head (3).
19. Apparatus according to claim 1, characterized in that the sensor head (3) made from resistant and low-wear material such as for example hardened steel is guided with respect to a sensor head holder (41) while being urged by spring force against the footwall (2).
20. Apparatus according to claim 19, characterized in that in the sensor head holder (41) adjacent each other in the travelling direction there are provided a plurality of for example three guide pins (42) which, surrounded by biasing springs (43), are guided with their ends (44) in bores (45) of the sensor head (3).

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