EP2366059B1 - PROCEDURE FOR SETTING AN AUTOMATIC LEVEL CONTROL OF THE PLANER IN PLANING PLANTS IN COAL MINING - Google Patents

Description

The invention relates to a method for setting an automatic level control of the plow in longwall operations in underground hard coal mining equipped with a hydraulic shield support and with a longwall conveyor guiding the plow on a plow guide designed thereon, the longwall conveyor including the plow guided on it being in its position in the mining direction via a the boom control supporting itself on the shield support can be changed and a control angle for setting the movement of the plow in the mining direction as a climbing movement, diving movement or neutral movement can be set by means of the boom control.

One problem with the automatic level control of plow operations both in the mining direction and in the direction of the plow is, on the one hand, to create a sufficiently large longwall opening to ensure the passage of the longwall equipment, for example without collisions between the plow and the shield support frames when the plow drives past, and on the other hand to keep the accumulation of tailings as low as possible during the extraction work, accordingly to limit the extraction work to the seam horizon as far as possible, without too much surrounding rock to record. The deposit data that were essentially available prior to the cutting, about seam thickness, lying and hanging wall level and the presence of saddles and/or troughs both in the mining direction and in the direction of travel of the plow, are too imprecise to allow an automated control of the plow and to be able to support expansion work, including compliance with the required longwall target height.

The plow equipped with chisels has a fixed cutting height due to the setting and a comparatively low cutting depth of around 60mm, so that in contrast to cutting extraction, the cutting height is not variable at least during a plow run along the longwall face. In plow operations, a level control of the plow is set up as a so-called boom control via a control cylinder arranged between the face conveyor as a fixed guide for the plow and the shield support frame attached to it. In addition to level-neutral control, the inclination of the longwall conveyor in the mining direction, which can be changed with the aid of the boom control, can also be used to impart a plunge movement in the mining direction to the longwall conveyor and thus to the plow guided on it during extraction runs, in which the plow tilts into the bedrock by cutting its ground chisels , or also a climbing movement in which the planer executes an upward stroke.

As part of the quarrying work with the plow, it should be possible to maintain a defined face opening, with this face opening being defined by the distance between the hanging wall cap and the bottom skid of the respective shield support frame in the area of its travel path. Especially when the bedrock changes or the bedrock is soft, which is less strong than the coal to be mined, it is important to maintain the target height of the face by constantly monitoring and adjusting the level control of the plow.

If the footing is firmer than the seam to be cut, level control of the plow is also possible using the well-known boundary layer plow method on the footing, in which the hard footing assumes a certain guiding function for the plow. As part of a method known for this purpose, a sensor carried along at the level of the ground chisel of the plow is used to determine whether the ground chisel of the plow is cutting in the surrounding rock, ie in the bedrock, or in the coal. This method is initially vulnerable on the hardware side, because the sensor in question and the associated evaluation computer are installed in or on the planer in an extremely harsh environment and are therefore subject to corresponding stresses or defects. Furthermore, the mobility of the plow requires a battery power supply for the hardware and radio data transmission using several transponders arranged in the longwall, with the radio conditions being very difficult to control, particularly in low longwalls with a high proportion of ferromagnetic components in the longwall equipment. In addition, this method is also associated with uncertainties in its statement or also causes corresponding time delays in the case of any necessary regulation, because a reasonably reliable statement about the material cut by the planer can only be made after a few planing strokes, i. H. after a few, usually about five times, driving past a shield support frame.

From the DE 10 2007 060 170 A1 a device for automated coal mining in the longwall of a mine is known, which comprises a plurality of support plates forming a support column extending through the longwall, a longwall conveyor attached to the longwall support and a plow guided on the longwall conveyor. With a view to automating the support work, inclination sensors are attached to the hanging wall cap, the bottom skid and the fracture shield of the shield support frames, so that the current geometric configuration of the respective shield support frame, in particular its height between the hanging wall cap and the bottom skid, can be determined via a computer unit. This enables central control of the individual shield support frames as cutting progresses in the longwall. However, this reference makes no suggestions as to how to solve the problems associated with planer level control.

Furthermore, in the DE 10 2005 005 869 A1 describes a method for controlling a mining machine in underground coal mining operations, which can therefore also be a plow, in which the geometry of the space created by the plow is recorded by appropriately aligned sensors and, using the measurement data recorded by the sensors, in a control unit at least one two-dimensional image of the room is produced and compared with the control unit stored in the control unit rule geometries of a normal room associated with the planer, with the occurrence of deviations being identified. However, this procedure only refers to the space created by the excavation and in this respect does not include an early level control of the plow.

The invention is based on the object of demonstrating a method of the type mentioned in which in all operating states of the longwall operation an automation of the planing and lining work with regard to the production of a defined longwall opening and/or the management of the longwall operation on the footwall is possible.

The solution to this problem, including advantageous refinements and developments of the invention, results from the content of the patent claims, which follow this description.

For this purpose, the invention provides a method in which for each planing pass the cutting depth and the control angle resulting as the difference between the inclination of the hanging wall cap of the shield support frames and the inclination of the face conveyor in the mining direction are recorded and the resulting change in face height per planing pass is calculated in a computer unit in such a way that in the computer unit each longwall layer of the longwall conveyor corresponding to a plow train is assigned a longwall height as the planned height, and when the respective longwall layer is reached by a shield support frame of the shield support which is behind the plow with a time delay, the actual height of the longwall is calculated on the basis of the values recorded by inclination sensors attached to the shield support frame are calculated and compared with the stored planned height, and a height difference value determined for the respective longwall layer between the planned height and the actual height in the sense of a self-learning effect vo n the computer unit is taken into account when specifying the control angle to be set for the planer in order to achieve a plan height of the strut in the subsequent planing passes.

The procedure according to the invention is initially based on the assumption that, depending on the cutting depth of the plow, there is a change in the face height with each plow stroke due to the set control angle compared to the hanging wall horizon that is assumed to be unchanged or constant and fixed by the hanging wall cap of each shield support frame resting on the hanging wall. A plunging of the plow adjusted via the control angle therefore leads to an increase in the face height, and a climbing of the plow leads to a reduction in the face height. Depending on the control angle set on the boom control, the theoretical plan height of the face after a plow stroke can be calculated based on an existing face height. However, due to the prevailing operating conditions, the planned height is not reached in operational practice; instead, the actual height of the brace is lower, which according to the invention is Reaching the respective longwall position is determined by the shield support frame which lags behind the plow with a time delay. The actual height is calculated on the basis of values recorded by inclination sensors attached to the shield support frame; however, the acquisition of the required values and the calculation method itself are not the subject of this invention.

Due to the discrepancy between the planned height and the actual height, if a control angle set on the boom control system were continuously used, a longwall would not reach the mining-related target height of the longwall, or would only do so with a considerable time delay. In this respect, according to the invention, the height difference value between the planned height and the actual height to be compensated for in each case to maintain the target height of the strut is already taken into account when setting the control angle, for example by achieving a specific height change with regard to maintaining the target height of the strut via a control cycle consisting of several planing strokes, the control angle is set larger or smaller by an angular amount corresponding to the determined height difference value, so that the actual height of the strut reached in each case corresponds to the desired height dimension. A closed control circuit for the level control of the plow is created on the basis of the values recorded and calculation of the height changes made with each plow train and the feedback of the longwall height with the same longwall position. Since the computer unit constantly records and monitors the conversion of the control angle into an actually occurring height change of the strut via the continuous shift, the use of a self-learning effect is given by self-learning algorithms stored in the computer unit, so that the control actually reaches or respectively certain control angles on the boom control assigns achievable face heights.

According to an embodiment of the invention it is provided that on the basis of the to reach the target height of the strut over a plurality control angle to be set by planing trains, the target inclination of the longwall conveyor in the mining direction that will result per planing train is precalculated in the computer unit and compared with the actual inclination of the longwall conveyor measured in each longwall layer per planing train by means of inclination sensors attached to the longwall conveyor, where deviations are optionally detected the control angle applicable for the next planing stroke is corrected. As a result, the time delay that is inevitably given by the checking of the actual height of the longwall on the longwall support frame that lags behind the plow can be shortened, so that a correspondingly large control loop is established. The inclination of the longwall conveyor is namely to be detected immediately after each control process with regard to the control angle and can also be used as a first correction value for the level control.

Insofar as it is provided according to an exemplary embodiment of the invention that the control angle specified by the computer unit is set in relation to the height difference value in the face height resulting per planing pass and the limit control angle of a reflection area determined as part of the self-learning effect is stored in the computer unit, within which valid, even different control angles do not produce any height changes in the face height, the influence of a footwall having a greater strength than the carbon strength is taken into account in the sense of boundary layer detection or boundary layer-guided planing. If the planing pulls do not change the face height despite a control angle on the boom control set to diving, it is clear that the planing is making prone contact, but the hard prone is preventing the planing from penetrating with a diving movement. Only when the control angle exceeds a certain size as the upper limit does the plunging movement become so strong that the planer cuts into the footing. On the other hand, the control angle at which the planer begins a climbing movement is recorded as the lower limit to execute. The area between the upper and the lower limit of the steering angle can be classified as a reflection area, in which changes in the steering angle have no influence on the face height, because the bedrock does not allow a change in the elevation of the planer and thus a boundary layer-guided planing, i.e. a Planing at the foothills is given. Due to the self-learning effect, the computer unit can identify the reflection area as a controller.

According to one embodiment of the invention, for cases in which the area of boundary layer-guided planing has to be left due to other operational influences, provision is made for the planer to perform a climbing movement or a diving movement when setting a required height for the strut to be reached causing the steering angle, the size of the respectively applicable reflection area is taken into account and the steering angle for bringing about the climbing movement or diving movement is set with a value lying outside the reflection area.

The self-learning effect of the plow with regard to the change in the actual height of the strut resulting from a set steering angle can only be valid as long as the ground chisel position on the plow is not changed. A change in the position of the ground bit on the plow also leads to a change in the control behavior of the plow, because a fixed control angle, for example, causes a smaller change in height when the ground bit of the plow is set to a lower plunging tendency than to a ground bit set to a greater plunging tendency. In this respect, according to an exemplary embodiment of the invention, it is provided that when the position of the ground bit of the plow changes with regard to a diving tendency, a climbing tendency or a neutral movement of the plow, information about the changed ground bit position is transmitted to the computer unit. Accordingly, according to an exemplary embodiment of the invention, it is provided that in the computer unit a characteristic map for the relationship between the steering angle and height difference value that matches the set ground bit position and has been learned from the previous cutting is called up. If such a map is not stored in the computer unit, the controller must first develop a map adapted to the new ground bit position during the subsequent planing strokes.

With the aid of the method according to the invention, it is possible to automatically drive through saddles and troughs in that, according to one embodiment of the invention, the course of troughs and/or saddles in the mining direction is determined by determining the inclination of the hanging wall cap of the shield support frames in the mining direction and an adjustment of the The cutting track of the plow is set parallel to the course of the hanging wall and the adjusted target height of the strut, which includes an additional height corresponding to the radius of the trough or saddle curvature, is produced by adjusting the control angle of the plow level control. If the control recognizes a decrease in the radius of the trough or saddle curvature, the calculated additional height is withdrawn again.

The continuous recording of changes in the height of the shield support frames allows conclusions to be drawn about the convergence that has occurred insofar as a height loss is determined on the shield support frame during the planing work, i.e. with the shield support standing still. Thus, according to an exemplary embodiment of the invention, it is provided that by continuously detecting the height of the shield support frames both from planing train to planing train and when the face is at a standstill, the convergence that is occurring is determined and continuously taken into account by adapting the height difference value to be used for setting the control angle of the planing level control becomes. A loss of height that has occurred must be compensated for by increasing the control angle to achieve or maintain the desired longwall height and thus by a Increase in the planned or actual height set by the planing work can be compensated again.

Provision can also be made here for an expected convergence to be included in the specification of the height difference value for downtimes in longwall operation. For example, before the weekend, the face opening can be increased in a targeted manner by increasing the control angle and thus increasing the height difference value, so that the target height of the face is available at the beginning of the week for the renewed start-up of the face despite a convergence that occurs at the weekend.

If, for example, floor elevations occur during operational standstills, which also lead to a reduction in the face height, such floor elevations lead to a change in the position of the longwall conveyor even when it is at a standstill, which is also recognized by the control system when the planing or conveyor operation is at a standstill. According to one exemplary embodiment of the invention, if the bed lifts while the face is at a standstill, the change in the inclination of the face conveyor is recorded when the plow is at a standstill and the control angle required to reach the desired height of the face is recalculated before the start of the planing work.

According to an exemplary embodiment of the invention, it is provided that a plurality of shield support frames and associated boom cylinders of the boom control are combined to form a group that can be controlled by means of a group control.

Since each shield support frame has a different setup tolerance when setting up the tilt sensors attached to it, a completely parallel mechanical alignment of the tilt sensors with the shield support frame is not possible. Depending on the quality of the basic mechanical alignment of the inclination sensors, the individual Shield support frame error in determining the steering angle as the difference between the inclination of the hanging wall cap and the inclination of the face conveyor. In order to minimize such errors, one embodiment of the invention provides that for each individual shield support frame within a group, the control angle for the associated boom cylinder is determined and a mean value is formed from the individual control angles of the shield support frames belonging to the group and in the group control one that corresponds to the mean value control angle is adjusted.

As torsion protection against overstressing of the interconnected chutes of the longwall conveyor, it can be provided that in the group controls of adjacent, control-technically connected groups of shield support frames in the longwall, the control angles applicable to the adjacent groups are compared with one another in such a way that mechanical overloading of the connections is avoided maximum differences between the control angles that apply to the adjacent groups are not exceeded by the partial channel sections of the longwall conveyor assigned to the groups.

For the same reason, it can be provided that differences in height between the groups in the position of the face conveyor are included in the comparison of the control angles applicable to adjacent groups. In this way, a maximum permissible bending radius of the conveyor string of the longwall conveyor around the mining progress axis is taken into account.

Accordingly, it can be provided that existing templates and/or reserves between the groups in the mining direction when the longwall conveyor and shield support frames run along the longwall front are included in the comparison of the control angles applicable to neighboring groups, whereby the maximum permissible bending radius of the conveyor string around the vertical axis of the longwall equipment is taken into account.

In order to reduce or rule out a mutual influence of the readjustment of the steering angle that may be required after each planing pass on individual shield support frames or jointly controlled groups of shield support frames, it is provided according to one embodiment of the invention that the readjustment of the control angle controlled by the computer unit for each planing pass is exclusively and once after the planing pass and the conclusion of the return process of the shield support frames.

With regard to the arrangement of the position of the face conveyor as an important parameter for determining or checking the steering angle as the difference angle between the inclination of the hanging wall cap of the shield support frames and the inclination of the face conveyor in the mining direction, according to a first exemplary embodiment of the invention, it is provided that a group of A central tilt sensor attached to the longwall conveyor is assigned to group control of shield support frames that are coupled to one another; alternatively, it can be provided that within a group of shield support frames coupled to one another by means of a support control, a plurality of inclination sensors are arranged on individual conveyor troughs of the longwall conveyor.

According to an exemplary embodiment of the invention, an inclination sensor attached to the face conveyor can be sufficient for determining the inclination of the face conveyor in the mining direction.

In order to improve the measurement quality, it can be provided that an inclination sensor unit attached to the longwall conveyor is designed as a twin sensor having two inclination sensors of the same type. This has the advantage that both sensors mutually check the display accuracy within a plausibility field and, in the event of deviations above a tolerance band, can issue an error message with regard to the display accuracy, with which a sensor drift can be detected.

Another advantage is that if one sensor fails, the second sensor can maintain its function and the system can generate a fault report.

The accuracy of the angle detection can be further improved if, according to one embodiment, an inclination sensor unit attached to the longwall conveyor consists of two identical sensors attached with opposite directions of rotation about the measuring axis. The opposite sensor arrangement in the direction of rotation around the measuring axis of two identical sensors in a differential circuit can be used to compensate for vibration-related (rotatory) errors in the sensors and significantly dampen the measured value display without losing accuracy. The average actual angle of the longwall conveyor, around which the longwall conveyor vibrates, can be displayed largely corrected for torsional vibrations, since both sensors vibrate with the same frequency and amplitude and with opposite evaluation in the interference method, the signal component superimposed by the vibration is compensated, so that the display angle is largely the same as remains when the system is idle.

Insofar as the hydraulic cylinders connected to a hydraulic supply and control unit are connected to one another as part of a group control of shield support frames and associated boom cylinders of the boom control used, the effect can occur that the longwall conveyor is pressed against the associated shield support frame when the plow drives past. In response to the associated displacement of hydraulic fluid, the hydraulic cylinders located in front of the plow in the direction of travel and belonging to the same group control can extend, which can result in unwanted changes in the respective control angle. To avoid such repercussions, it can be provided that the hydraulic boom cylinders of the boom control, which are supported between the shield support frames and the face conveyor, can be released hydraulically by means of individually acting on their piston surface and their annular surface Check valves can be locked hydraulically after reaching their control position, the check valves being connected to the associated group control by means of associated control lines.

Within the scope of such individually locked hydraulic cylinders, it may be necessary from time to time to synchronize the boom cylinders, and for this purpose, according to one proposal, all boom cylinders are moved against an end stop, with the control angle required in the respective face layer of the face conveyor and the plow guided on it then being set .

Fig. 1

eine Strebausrüstung mit einem eine Tauchbewegung des Hobels vorgebenden Steuerwinkel in einer schematischen Seitenansicht,

Fig. 1a

den Verlauf der Höhenentwicklung im Streb beim Einsatz der Strebausrüstung gemäß Figur 1 während eines eine Mehrzahl von Hobelzügen aufweisenden Regelzyklus,

Fig. 2

in einer schematischen Darstellung das Verhältnis der an der Auslegersteuerung eingestellten Steuerwinkel im Verhältnis zu dem sich tatsächlich einstellenden Steuerwinkel bei einem harten, eine größere Festigkeit als die Kohle aufweisenden Liegenden,

Fig. 2a

den Gegenstand der Figur 2 in einer anderen Darstellungsweise,

Fig. 2b

den Gegenstand der Figur 2 unter Einbeziehung des Einflusses der Bodenmeißelstellung,

Fig. 3

den Gegenstand der Figur 2 bei einem weichen, eine geringere Festigkeit als die Kohle aufweisenden Liegenden,

Fig. 3a

den Gegenstand der Figur 3 in einer Darstellungsweise gemäß Figur 2a,

Fig. 4a

das Verhalten der Auslegersteuerung innerhalb einer Gruppensteuerung ohne Einzelsperrung der Auslegerzylinder,

Fig. 4b

den Gegenstand der Figur 4a bei Einzelsperrung der Auslegerzylinder,

Fig. 5

den bei einer automatischen Niveausteuerung einzustellenden Verfahrensablauf in einer schematischen Darstellung.

The invention is discussed again in individual aspects below with reference to the drawing; here show:

1

a longwall equipment with a control angle that predetermines a plunge movement of the plow in a schematic side view,

Fig. 1a

the course of the height development in the longwall when using the longwall equipment figure 1 during a control cycle having a plurality of planing trains,

2

in a schematic representation, the ratio of the control angle set on the boom control in relation to the control angle that actually occurs with a hard base that is stronger than the coal,

Figure 2a

the subject of figure 2 in a different way,

Figure 2b

the subject of figure 2 including the influence of the soil pick position,

3

the subject of figure 2 in the case of a soft footing that is less firm than the coal,

Figure 3a

the subject of figure 3 in a representation according to Figure 2a ,

Figure 4a

the behavior of the boom control within a group control without individual blocking of the boom cylinders,

Figure 4b

the subject of Figure 4a with individual blocking of the boom cylinders,

figure 5

the procedure to be set for an automatic level control in a schematic representation.

In the figure 1 The longwall equipment shown schematically has a shield support frame 10 with a hanging wall cap 11 and a bottom skid 12; Between the bottom skid 12 and the hanging cap 11, two stamps 13 are attached in parallel, of which in figure 1 only one stamp is recognizable. While the front (left) end of the hanging wall cap 11 protrudes in the direction of the extraction machine, a breach shield 14 is articulated at the rear (right) end of the hanging wall cap 11. The structure of such a shield support frame 10 is known, so that it will not be explained further. An inclination sensor 15 is attached at least to its hanging wall cap 11; as not shown in more detail, further inclination sensors are attached to the base skid 12 and to the rupture shield 14 and/or to the supporting links carrying the rupture shield 14 on the shield support frame 10 . The height of the shield support frame between the hanging wall cap 11 and the bottom skid 12 can be calculated with the aid of the measured values recorded by the inclination sensors.

A face conveyor 16 is attached to the shield support frame 10 and has a plow guide 18 with a plow 17 guided thereon on its (left) side facing the working face (not shown). The longwall conveyor 16 with the plow 17 guided thereon is arranged such that it can be pivoted relative to the shield support frame 10 by means of a boom cylinder 19 . At the in figure 1 illustrated embodiment is the Longwall conveyor 16 with plow 17 is pivoted in the direction of a diving movement, with a control angle 20 set via boom cylinder 19, which is the difference angle between the position of hanging wall cap 11 of shield support frame 10 and the inclination of longwall conveyor 16 in the mining direction. For this purpose, the respective inclination of the longwall conveyor 16 in the mining direction can be detected or determined via an inclination sensor 15 attached to the longwall conveyor 16 .

How to do this Figure 1a with the representation of 17 planing strokes within the framework of a control cycle, an assumed constant cutting depth 21 is achieved with each planing stroke, specifically for each uphill run 22 and for each downhill run 23. Due to a plunge setting in the illustrated embodiment, in the second Half of the control cycle decreasing predetermined control angle is determined in the assigned computer unit for each planing pass 22, 23, the expected plan height of the longwall or the achievable plan height difference per planing move, which over the 17 planing moves of the in Figure 1a illustrated control cycle is plotted as curve 24. The respective check of the actually reached actual height of the strut leads to a curve as plotted as curve 25 . Accordingly, the reference number 26 designates the amount of height difference that has to be cut in order to achieve the desired nominal height of the strut. The amount 27 corresponds to the height difference actually cut free in the actual height of the strut, so that a height difference value 28 can be determined as the difference between the amounts 26 and 27 or can be determined by the computer unit. Insofar as the control angle 20 is to be set for the individual ascents and descents 22, 23 of the plow, the control angle must be set so much larger by the height difference value 28, taking into account the height loss between the planned height and the actual height, that ultimately the actual Height increase 27 corresponds to the required height increase 26. This means that the curve 24 resulting from the steering angle for the planned height is to be specified in such a way that the curve 25 for the actual height ends at the amount of the required height difference. As far as in the computer unit Self-learning algorithm is integrated, the control or the computer unit is able to learn the actual implementation of the planned height in the actual height and use it to calculate the control strategy for the following planing trains. In the case of newly started mining operations, a mining progress of, for example, 20m must first be run through with a manual plow level control, in which the control system passively learns the control behavior for the longwall in question. The automatic planing level control can then be put into operation, which continues to learn the control behavior as mining progresses and continuously optimizes the control strategy.

The implementation of the control angle 20 in a face height difference for setting or maintaining a target height of the face depends on the surrounding rock conditions, especially in the footwall, because the overhanging wall should remain as unscratched as possible, since it forms the guide horizon for the shield support. If the bottom is softer than the coal to be mined, it is very difficult to maintain a target longwall height because the plow has to be controlled within the target height range without a guidance horizon, so to speak "floating". This requires frequent control interventions, since the plow conveyor system constantly runs out of the target horizon, so that continuous readjustment has to be carried out. Due to the nature of the process, this unstable balance in control causes a wide range of variation in the face height, which entails the risk of tailings being cut, coal growing and the extension leaving the adjustment range.

If the base is harder than the coal, the base horizon can be included as a guide level for the planing work, in the sense of boundary layer planing. A hard base means that, despite a control angle set to plunging, the plow initially does not cut into the base and, in this respect, no actual height change occurs despite the plan height per plow stroke resulting from the setting of the control angle. The lying reflects, so to speak, the Control movements of the planer, which is why the area mentioned for the control angle can also be referred to as the reflection area. This reflection area in relation to the set control angle extends from a lower limit, which marks the limit line for climbing the planer, to an upper limit, which, when exceeded, due to the set control angle, the planer overcomes the resistance of the footing, cuts into the footing and thus performs an effective diving movement. These areas are in figure 2 , right half, shown as an example with a diving area 30 applicable to the currently applicable steering angle, a reflection area 31 and a climbing area 32.

As already explained, the steering angle that is actually effective with regard to the actual height of each planing train deviates from the set steering angle, as shown in figure 2 , left half. In this case, with the effective control angle, the reflection area is almost completely eliminated despite a control angle set in the reflection area, because control angles set in the reflection area do not cause any actual height difference here.

The relevant conditions are over Figure 2a also recognizable with the control characteristic 33 reproduced therein. If the steering angle is set between + 3gon and - 3gon, the effective steering angle does not change; The control strategy is based on the assumption that the control angle is set in the middle of the reflection area when a reflection area is detected during the planing work by the control or the computer unit in order to have sufficient leeway in particular for fluctuations in the implementation of the set control angle in the machine technology, without the reflection area is left and the planer effectively performs unwanted tilting movements.

In Figure 2b are they off Figure 2a resulting conditions, taking into account the dipping tendency that can be set on the bottom chisel of the planer or climbing tendency shown. As the dashed line 34 for the control characteristic shows, the control characteristic for plunging the plow becomes flatter, the weaker the basic plunging tendency set via the bottom chisel of the plow is set, and the later an effective plunging movement can be initiated. The same applies to the climbing area. The weaker the basic tendency to dive set via the ground chisel, the steeper the dashed control characteristic curve 34 runs in the climbing area for climbing, and the earlier a climbing movement of the plow can be initiated.

In Figures 3 and 3a Are the conditions appropriate? figures 2 and 2a for the application in which the base is softer than the coal to be extracted. In this case, there is no guidance horizon formed by the bedrock, so that the planer follows the setting of the steering angle immediately. This eliminates a reflection area ( figure 3 ), and there is a seamless alternation between climbing the plane and diving the plane ( Figure 3a ). As far as this transition in Figure 3a is shown at + 2gon, a diving tendency set at the bottom chisel of the planer is expressed therein.

In Figures 4a, 4b the influence of the design of the boom cylinder can be seen. How out Figure 4a results, when the boom cylinders 35 are connected to one another, the effect can occur that when the plow (planing passage) drives past, the longwall conveyor is pressed against the associated shield support frame (not shown), so that hydraulic fluid is displaced from the boom cylinders 35 arranged in the area of the plow passage . The hydraulic fluid displaced there can flow to boom cylinders 35 located in front of the plow in the direction of travel and belonging to the same group control and there ensure that the boom cylinders are extended, which at the same time involves a change in the steering angle in this area. To avoid such repercussions, it can be provided that the boom cylinders 35 are each provided with an individual shut-off, see above that the boom cylinders 35 can be locked hydraulically after reaching their control position. How out Figure 4b results, the boom cylinders 35 remain unaffected by the plow passage.

How finally turned out figure 5 results, in order to minimize the mutual influencing of neighboring control groups of shield support frames, a control sequence following the plow can be activated, in which the shield support is first moved in a controlled manner after the plow passage. After completion of the reverse process, the individual control groups of the shield support frames receive the control order one after the other to set the control angle for the next planing pass and then no longer carry out any readjustment. With this, the possible influence of a control group by the following control group is tolerated. Any deviations in the control angle that occur are included in the future control strategy by the computer unit, but the control angle is only adjusted after the next planing pass. Due to such a strategy, the control shaft passes through the face trailing the plow. Unstable regulation due to feedback effects from adjacent control groups on one another is reliably avoided.

The features of the subject matter of these documents disclosed in the above description, the patent claims, the summary and the drawing can be essential for the realization of the invention in its various embodiments individually or in any combination with one another.

Claims (23)

1. Method of setting an automatic level control of the plow (17) in longwall mining operations, in underground coal mining, equipped with a hydraulic shield support and a face conveyor (16) that guides the plow (17) on a plow guide mechanism (18) formed thereon, wherein the position of the face conveyor (16), including the plow (17) guided thereon, can be changed in a exploitation direction by means of a boom control mechanism that is supported on the shield support, and by means of the boom control mechanism, a control angle (20) for setting the motion of the plow (17) in the exploitation direction as a climbing motion, dropping motion or a neutral motion can be set, wherein for each stroke of the plow, the cutting depth (21) and the control angle (20) which is derived as a differential angle between the inclination of the top canopy (11) of the shield support frame (10) and the inclination of the face conveyor (16) in the exploitation direction are determined and, in a calculating unit, a face height change per plow stroke is calculated therefrom such that in the calculating unit, a face height, as a projected height, is associated with each face position of the face conveyor (16), wherein the face position corresponds to a plow stroke, and wherein when a shield support frame (10) that trails behind the plow (17) in terms of a time delay reaches a respective face position, an actual height of the face is calculated on the basis of values detected by inclination sensors (15) mounted on the shield support frame (10) and is compared with the stored projected height, and wherein for the subsequent plow strokes, a height differential value (28), between the projected height and the actual height, determined for a respective face position, is taken into consideration in the sense of a self-learning effect of the calculating unit when the control angle (20) for the plow (17) that is to be set to achieve a projective height of the face is prescribed.
2. Method according to claim 1, wherein on the basis of the control angle (20), which is to be set for achieving a target height of the face via a control cycle that includes a plurality of plow strokes, the target inclination of the face conveyor (16) in the exploitation direction, which target inclination results per plow stroke, is predetermined in the calculating unit and is compared for adjustment purposes, with the actual inclination of the face conveyor (16) measured in each face position per plow stroke by means of inclination sensors (15) mounted on the face conveyor (16), wherein if deviations are recognized, optionally correcting the control angle (20) applicable for the next plow stroke.
3. Method according to claim 1 or 2, wherein the control angle (20) respectively prescribed by the calculating unit is established in relationship to the height differential value (20) resulting per plow stroke, and in the calculating unit, the limiting control angle of a reflection region (31) determined due to the self-learning effect is stored, within which region respectively applicable even different, control angles generate no changes in height of the face.
4. Method according to claim 3, wherein with the setting of a control angle (20) that is necessary for achieving a target height of the face, and that effects a climbing motion or a dropping motion of the plow (17), the magnitude of the respectively applicable reflection region (31) is taken into account, and the control angle (20) is set to a value beyond the reflection region (31) for bringing about the climbing motion or the dropping motion.
5. Method according to one of the claims 1 to 4, wherein the position of the base chisel of the plow changes with respect to a dropping tendency, a climbing tendency or a neutral motion of the plow, the calculating unit conveys information about the base chisel position.
6. Method according to claim 5, wherein the calculating unit, a performance characteristic that matches the set base chisel position, and that is acquired from the past extraction, is called up for the relationship of control angle and height differential angle relative to one another.
7. Method according to one of the claims 1 to 6, wherein via the determination of the inclination of the top canopy (11) of the shield support frame (10) in the exploitation direction, the pattern or contour of depressions and/or saddles in the exploitation direction is determined, and in the calculating unit an adaptation of the path of cut of the plow (17) parallel to the contour of the roof is set and the adapted target height of the face, which includes an additional height corresponding to the radius of the depression or saddle curvature, is established by an adaptation of the control angle (20) of the plow level control.
8. Method according to one of the claims 1 to 7, wherein by means of a continuing detection of the height of the shield support frame (10), not only from plow stroke to plow stroke, but also at standstill of the longwall mining operation, the respectively occurring convergence is determined and continuously taken into account by an adaptation of the height differential value (28) that is to be used for setting of the control angle (20) of the plow level control.
9. Method according to claim 8, wherein for standstill times of the longwall mining operation, a convergence that is to be expected is included in the determination of the height differential value (28).
10. Method according to claim 8 or 9, wherein with a raising of the floor that has occurred during a standstill of the longwall mining operation, the change of the inclination of the face conveyor (16) is detected during the standstill of the plow (17), and prior to beginning the plowing work the control angle (20) required for achieving the target height of the face is recalculated.
11. Method according to one of the claims 1 to 10, wherein a plurality of shield support frames (10) and pertaining boom cylinders (35) of the boom control mechanism are connected to form one group that can be controlled by means of a single group control mechanism.
12. Method according to claim 11, wherein for each individual shield support frame (10) within a group, the control angle (20) for the pertaining boom cylinder (35) is determined, and from the individual control angles of the shield support frames (10), an average value is formed and a control angle (20) that corresponds to the average value is set in the group control mechanism.
13. Method according to claim 11 or 12, wherein in the group control mechanisms of groups of shield support frames (10) that are adjacent in the longwall equipment and are connected from a control standpoint, the control angles (20) applicable for the adjacent groups can be compared and balanced with one another such that to avoid a mechanical overstretching of partial chute lengths of the face conveyor (16) associated with the groups, preset maximum differences between the control angles (20) applicable for the adjacent groups are not exceeded.
14. Method according to claim 13, wherein height differences in the position of the face conveyor (16) existing between the groups can be used or taken into account in the comparison of the control angles (20) applicable for adjacent groups.
15. Method according to claim 13 or 14, wherein leading or forward positions and/or rearward or trailing positions that exist between the groups in the exploitation direction during the progress of face conveyors (16) and shield support frames (10) along the long wall face can be taken into consideration in the comparison of the control angles (20) applicable for adjacent groups.
16. Method according to one of the claims 1 to 15, wherein the readjustment of the control angle (20) with each plow stroke, which is controlled by the calculating unit, is effected exclusively and one time following the passage of the plow and at the end of the stepping of the shield support frames (10).
17. Method according to one of the claims 11 to 16, wherein a central inclination sensor (15) mounted on the face conveyor (16) is respectively associated with a group of shield support frames coupled to one another by means of the group control mechanism.
18. Method according to one of the claims 11 to 16, wherein a plurality of inclination sensors, which are disposed on individual conveying chutes of the face conveyor (16) are respectively arranged within a group of shield support frames (10) that are coupled to one another by means of a boom control mechanism.
19. Method according to one of the claims 1 to 18, wherein the inclination of the face conveyor (16) is measured by means of an inclination sensor (15) mounted on the face conveyor (16).
20. Method according to one of the claims 1 to 19, wherein an inclination sensor unit mounted on the face conveyor (16) can be embodied as a twin or double sensor that is provided with two inclination sensors having the same construction.
21. Method according to one of the claims 1 to 19, wherein an inclination sensor unit mounted on the face conveyor (16) is comprised of two similar sensors that are mounted so as to have an opposite direction of rotation about the measurement axis.
22. Method according to one of the claims 1 to 21, wherein the hydraulic boom cylinders (35) of the boom control mechanism, which are supported between the shield support frames (10) and the face conveyor (16) can, after they have reached their control position, be hydraulically blocked by means of hydraulically releasable check valves that individually act upon the piston and ring surfaces of the boom cylinders, whereby the check valves are connected with the pertaining group control mechanism via associated control lines.
23. Method according to claim 22, wherein at time intervals a synchronization of the boom cylinders (35) is undertaken in that all of the boom cylinders (35) are run against an end abutment and subsequently the control angle (20) that is required in the respective face position of the face conveyor (16) and the plow (17) guided thereon is set.

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