US 3371964 A
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March 5. 1968 KARL-HEINZ WEBER 3,371,964
METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Filed June 20, 1966 4 Sheets-Sheet 1 FIG. I.
WWWWWWWWWW INVENTOR Karl-Heinz Weber March 5. 1968 KARL-HEINZ WEBER 3,371,964
METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Filed June 20, 1966 4 Sheets-Sheet 2 z M 2:- WW 2, z
March 5, 1968 KARL-HEINZ WEBER METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Filed June 20, 1966 4 Sheets$heet 5 ULTRASONIC ULTRASONIC PULSE PULSE RECEIVER TRANSMITTER TRANSMITTER GENERATOR ,2? AMPLIFIER INTEGRATOR ERROR A9 SIGNAL STAGE ELL Q POWER SUPPLY a RECORDING 42 TRANsIsTOR CONTROL INSTRUMENT STAGE MEANS I I I I F|G.3.
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March 5. 1968 KARL-HEINZ WEBER 3,371,964
METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Filed June 20, 1966 4 Sheets-Sheet 4 (D N) m m s 9| $1 l 2 ml E z a w w u WW 0 United States Patent Ofiice 3,371,964 Patented Mar. 5, 1968 3,371,964 METHOD AND APPARATUS FOR SCANNING AND MONITORING THE ROOF OF SEAMS MINED BY CUTTING MACHINES Karl-Heinz Weber, Witten-Heven, Germany, assignor to Gebr. Eickhoif, Maschinenfabrik and Eisengiesserei m.b.H., Bochum, Germany, a corporation of Germany Filed June 20, 1966, Ser. No. 558,727 Claims priority, application Germany, June 30, 1965, E 29,612 5 Claims. (Cl. 2991) This invention relates to mechanized mining of veins, such as the mechanized longwall method of mining coal seams and, more particularly, to scanning and monitoring the roof of the seams while mining is in progress, and to suitable scanning apparatus.
In the mining of coal veins, for example by the mechanized longwall mining method, it is known to employ cutting machines that out along the longwall face of the coal seam while moving longitudinally along said longwall face on a guideway or track placed therealong. A suitable cutting machine for performing this operation comprises essentially a machine body movable on said guideway, and a pair of support arms pivotally attached to the body and carrying respectively two cutting tools, for example cutting rollers, hereinafter referred to also as upper and lower cutting tools. As the cutting machine advances along the longwall face, the lower cutting roller works the floor of the coal sea-m while the upper cutting tool works the upper seam portion thereby exposing the seam roof. In cutting machines of this type, the upper cutting tool may be designed to follow automatically the seam roof of veins varying in thickness. For example, the upper cutting tool may be controlled in response to scanning the seam roof with a radiation beam from an isotope.
In mechanical mining operations, with no attendant present at the seam face, the conveyor means or haulagev equipment for taking up the coal mined by the cutting machine and hauling it away is advanced mechanically toward the face of the seam, usually by cylinder means, before commencing with the next cut along the longwall face. This operation is controlled from the roadway at which the longwall face usually terminates, the roadway as a rule, but not necessarily, extending substantially perpendicularly to the longwall face. The roof support structure, likewise, is advanced mechanically toward the longwall face before performing the next cut therealong. The sequence of erecting and advancing the support structure toward the coal face, completing a cut along said face, again advancing the support structure, completing the next cut, and so on, is similar to that practiced in manual mining operations, whereby in the advanced position of the support structure, the upper beams thereof, usually referred to as caps, extend sulficiently far so as to support the seam roof above the guideway, haulage equipment and the cutting machine without, however, interfering with the cutting action of the upper cutting tool during the next out along the longwall face.
When the seam roof is of poor quality, the mining equipment breaks not only the coal but occasionally also portions of the overburden, thus producing breaks and cavities that extend sometimes deep into the seam roof. As a result, the support structure might fail to provide adequate protection against any rocks that might fall from such cavities and damage the cutting machine and other equipment.
It is an object of the present invention to prevent damage to the equipment that might occur as a result of seam roofs of poor quality or irregularities therein.
The invention, briefly, accomplishes this object by scanning continuously the shape or contour of the seam roof and observing a recording that is representative of the seam roof contour at a station remote from the coal face. Preferably, the recording is a visual display of the seam roof contour, and the remote observation station is in the roadway. The invention thus facilitates shutting down of the equipment before damage thereto might occur. If de-' sired, the equipment may be shut down automatically by rendering the control means for the equipment responsive to signals that vary with the recording.
A specific embodiment of this invention resides in a method of scanning and monitoring the roof of a seam that is mined by a cutting machine having a machine body and a support arm pivotally attached to the machine body and carrying acutting tool for cutting and exposing the seam roof as the cutting machine advances along the face of the seam, said method comprising the steps of measuring continuously the height of the seam roof as determined by the inclination of the support arm carrying the cutting tool that follows and exposes the seam roof while cutting along the face is in progress, determining the height of the seam roof that had been exposed by a previous cut along the face by means of ultrasonic altimeter means disposed on the cutting machine for scanning the seam roof, and recording an error signal which is representative of the difference between the two height values obtained.
In the specific embodiment more fully described hereinafter, error signals of one, say positive, polarity are obtained when the seam roof rises in the direction the cutting machine is advancing along the face of the coal seam. Error signals of the opposite polarity are obtained when the seam roof declines in the direction the cutting machine advances. The error signal is zero when the seam roof is substantially level in the advancing direction. Since, as mentioned above, during the cut along the face of the seam, the caps of the support structure provide support for the roof straight above the cutting machine and haulage equipment, the scanning ultrasonic waves pick up also said caps, thus facilitating also to monitor the proper location of the caps.
A suitable apparatus for carrying out the novel scanning and monitoring method comprises essentially: a variable impedance means responsive to the inclination of the pivotally attached support arm carrying the cutting tool exposing the seam roof for producing a first signal representative of the height of the seam roof where exposed by the cutting tool; an ultrasonic transmitter disposed on the body of the cutting machine for transmitting ultrasonic waves to scan the seam roof; an ultrasonic receiver arranged to receive the waves reflected by the seam roof and an integrator for producing a second signal representative of the height of the scanned sea-m roof; an error signal stage for combining the first and second signals and producing an error signal; an indicating instrument including a recording drum and being located at a station remote from the mining stat-ion; an electrical connection between the error signal stage and the indicating instrument; and a drive for rotating the recording drum, said drive being responsive to the main drive for advancing the cutting machine along the face of the seam.
The indicating instrument is located preferably in the roadway. The electrical connection between the error signal and the indicating instrument is preferably included in the utility cable that may also contain the power supply and control conductors for the drive means of the cutting tools. The variable impedance means may be a potentiometer.
In order to monitor the contour of the seam roof even more precisely, two ultrasonic altimeter means, each including a transmitter and receiver, may be disposed sideby-side on the body of the cutting machine for scanning the seam roof at different distances respectively from the' face of the seam. Each altimeter means is associated with a separate integrator and a separate error signal stage, the two error signal stages being connected to the indicating instrument. The apparatus otherwise is similar to that described above, i.e., each error signal stage is connected to the variable impedance means so as to combine the signal from the associated integrator with that from said impedance means; thus two error signals are produced which are recorded simultaneously by the indicating instrument, the recordings visually indicating whether the seam roof rises, declines, or remains substantially level as the cutting machine advances along the face while cutting is in progress.
Further advantages and objects of the present invention will become more readily apparent from the following description and the accompanying drawings, in which:
FIGURE 1 is a side view of a cutting machine as it advances along the face of a scam, the machine being equipped with ultrasonic altimeter means in accordance with this invention;
FIG. 2 is an elevation view of a similar cutting machine as it cuts along the longwall face of the seam toward the roadway in which main drive means, power supplies and control means for the mining equipment are located;
FIG. 3 shows schematically various elements of a monitoring apparatus in accordance with the present invention;
FIG. 4 shows a diagram as recorded by the indicating instrument; and
FIG. 5 shows a modification, similar to FIG. 2, with the exception, however, that two ultrasonic altimeter means are disposed on the cutting machine.
Referring to FIGS. 1 and 2, the arrow denotes the direction in which the cutting machine 11 advances along the longwall face of the seam. In the illustrated embodimerit the haulage equipment includes a track or guideway 12 on which the machine 11 is movable in either direction along the longwall face. The cutting machine which per se forms no part of the present invention, comprises essentially a machine body or carriage 11a, a lower support arm 13 pivotally attached to the body 11a and carrying a lower cutting roller 14 for working the floor of the coal seam, and an upper support arm 15 pivotally attached to the machine body and carrying an upper cutting roller 16 for working the upper portion of the seam and exposing the seam roof, i.e., the machine is so designed that the upper cutting roller may follow the seam roof. When cutting in the direction opposite to that indicated by the arrow 10 is desired, the support arms 13 and 15 are pivotally moved upwardly and downwardly respectively such that the roller 16 works the floor and the roller 14 the upper portion of the coal seam. While cutting along the face is in progress the caps 17 of the support structure (not otherwise shown, except for the support posts 17a in FIGS. 2 and 5) support the overburden 18 and extend sufficiently far toward the face of the seam so as to support also the overburden directly above the machine body 11a and the haulage equipment including the track 12 without, however, interfering with the cutting action of the cutting rollers. FIG. 1 shows a cavity 19 in the seam roof 20. In accordance with this invention an ultrasonic altimeter means 21 including a transmitter 22 and a receiver 23 (FIG. 3), is disposed on the machine body 11a.
Referring now to FIG. 3, the apparatus for carrying out the scanning and monitoring method in accordance with this invention includes a pulse generator 24 connected through a pulse transmitter 24a to energize the ultrasonic transmitter 22 for producing ultrasonic waves that scan the seam roof as the cutting machine 11 advances along the face of the seam. The ultrasonic receiver 23 is designed for receiving the waves reflected by the seam roof and has its output connected to an integrator 26 through an amplifier 27, the integrator 26 being designed for producing an electrical signal that varies with the height of the scanned seam roof. A variable impedance means in the form of a potentiometer 28 is responsive to the in clination of the arm 15 that varies with the thickness of the seam; hence, the impedance means is capable of providing a signal that varies with the height of the seam roof where contacted and exposed by the upper cutting tool 16. The two signals are combined in the error signal stage 29 to produce an error signal that is applied through the electrical connection 30 in the utility cable 31 to the control and power supply means 32 for the cutting ma chine, the means 32 being located in the roadway 33, FIG. 2. The means 32 is connected through the electrical connection 34 to an indicating instrument 35 which includes a rotatable recording drum.
In operation, longitudinal advancement of the cutting machine 11 along the longwall face 36 of the coal seam 37 is accomplished by traction means which in the shown embodiments comprises a drag chain 38, FIG. 2, attached to the machine body and extending therefrom to a drum 39 of a winch 40. The recording drum of the instrument 35 is operatively coupled to the drum 39 by means known in the art, for example, through a speed-responsive signal producing means 41, a transistor stage 42 and an electrical connection 43, thereby effecting rotation of the recording drum corresponding to the longitudinal motion of the cutting machine.
Referring now to FIG. 4, the abscissa denotes the direction of advancement of the cutting machine along the longwall face 36 and, hence, gives a measure of the length of the face 36. The ordinate indicates the magnitude of the error signals from the error signal stage 29, i.e., the shown diagram represents the error signals over the length of the face mined. The substantially horizontal portion of the curve indicates that over the corresponding section of the longwall face the seam roof is substantially level, the small rectangular indentations indicating the 10- cations of the caps 17 in FIG. 1. The ascending right-hand portion of the curve corresponds to the cavity 19 in FIG. 1. By observing the continuously recorded curve the attendant is therefore enabled to detect irregularities in the seam roof and, if deemed advisable, to shut down the cutting machine before any damage thereto occurs.
Referring to FIG. 5, the cutting machine 11 is equipped with two ultrasonic altimeter means 21a and 21b, each including a transmitter and receiver, disposed side-by-side on the machine body for scanning the seam roof at different distances respectively from the face of the seam. Otherwise FIG. 5 is similar to FIG. 2, like reference numerals being employed in both figures to denote the same elements. Each of the altimeter means 21a and 21b is associated with a separate integrator and a separate error signal stage in the manner previously described, the two error signal stages providing two error signals that are recorded by the indicating instrument. The simultaneous recording of the two error signals are indicative of the course of the seam roof in both the direction parallel to the face of the seam and the direction perpendicular thereto.
While the invention has been shown in connection with specific embodiments, it will be apparent to those skilled in the art that various modifications may be made without departing from the spirit and scope thereof. For example, the operation of the cutting machine may be controlled in response to said error signal. Thus automatic shut down of the cutting machine may be accomplished by rendering the control portion of the aforesaid control and power supply means responsive to the error signals, i.e., the control means may be adjusted for automatic shut down in response to the error signals exceeding a predetermined magnitude.
I claim as my invention:
1. Method of scanning and monitoring the roof of a seam mined by a cutting machine having a support arm carrying a cutting tool for cutting the seam along a face thereof and following the seam roof to expose the latter as the cutting machine advances along the face of the seam, said method comprising the steps of producing a first signal in response to the inclination of said support arm while cutting along the seam face is in progress, scanning a portion of the seam roof exposed by a previous out along the face of the seam by means of ultrasonic altimeter means disposed on the cutting machine, producing a second signal responsive to said ultrasonic altimeter means, and recording continuously the difference between said first and second signals while cutting along the seam face is in progress.
2. The method of claim 1, including the step of controlling the operation of said cutting machine in response to an error signal derived from the difference of said first and second signals.
3. Apparatus for scanning and monitoring the roof of a seam mined by a cutting machine having a support arm carrying a cutting tool for cutting the seam along a face thereof and following the seam roof to expose the latter, said apparatus comprising an adjustable impedance means responsive to the inclination of the support arm for producing a first signal, ultrasonic altimeter means including a transmitter and receiver disposed on the cutting machine for scanning a previously exposed portion of the seam roof as the cutting machine cuts along the seam face, integrator means responsive to said altimeter means for providing a second signal, an error signal stage for combining said first and second signals and producing an error signal, and indicating means located at a station remote from the cutting machine and being elec- 3O trically connected to said error signal stage for recording continuously the error signal.
4. The apparatus of claim 3, wherein a second ultrasonic altimeter means is disposed on the cutting machine side-by-side with the first-mentioned ultrasonic altimeter means for scanning the seam roof along a path parallel substantially to the seam face at a distance therefrom substantially different from that between the seam face and the first-mentioned altimeter means; said apparatus including second integrator means responsive to said second altimeter means for producing a third signal, and a second error signal stage for combining said first and third signals and producing a second error signal, said second error signal stage being electrically connected to said indicating means for recording the second error signal simultaneously with the first-mentioned error signal.
5. The apparatus of claim 3, wherein said indicating means comprises a recording drum operatively coupled to the cutting machine for rotational movement corresponding to the motion of the cutting machine along the seam face while cutting is in progress.
References Cited UNITED STATES PATENTS 2,761,666 9/ 1956 Heimaster et al 2991 3,108,789 10/1963 Heimaster et al 299-1 FOREIGN PATENTS 966,714 8/ 1964 Great Britain.
ERNEST R. PURSER, Primary Examiner.