Patent Publication Number: US-11655711-B2

Title: Roof support including extendable links

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of prior-filed, U.S. Provisional Patent Application No. 62/735,586, filed Sep. 24, 2018 the entire contents of which are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to roof supports, e.g., for an underground mine, particularly a roof support including extendable links. 
     BACKGROUND 
     Longwall mining systems include a mining machine, such as a longwall shearer, and roof supports. A roof support includes a canopy having a forward end that is positioned proximate the mine face, but spaced apart from the face by a tip-to-face distance or clearance distance. Unsupported space between the canopy and the face is important for discrepancies encountered as a shearer cuts the mining surface. 
     SUMMARY 
     In one aspect, a roof support includes a base, a canopy for engaging a mine surface, a shield coupled to the canopy, and a link coupled between the base and the shield. The canopy is supported relative to the base and includes an end configured to be spaced apart from a mine face by a distance. The link is movable between a first position and a second position, and movement of the link between the first position and the second position causing the distance to change. 
     In some aspects, the first position is a retracted position and the second position is an extended position. 
     In some aspects, the link is a telescoping box link including a first portion proximate a first end, a second portion slidably coupled to the first portion, and a linear actuator for moving the second portion relative to the first portion. 
     In some aspects, the roof support further includes a sensor configured to detect a position of the canopy relative to the mine face. 
     In some aspects, the link is a first link, and the roof support further includes a second link coupled between the base and the shield, the first link configured to be positioned between the second link and the mine face. 
     In some aspects, the roof support further includes a jack supporting the canopy relative to the base, the jack being extendable and retractable relative to the base. 
     In some aspects, the link is one of a pair of links coupled between the base and the shield, the pair of links being movable between a first position and a second position, and movement of the pair of links between the first position and the second position causes the distance to change. 
     In another independent aspect, a system is provided for controlling a roof support including a canopy for engaging a mine surface. The system includes a sensor configured to generate a signal indicative of a position of an end of the canopy, and a controller. The controller is configured to receive the signal indicative of the position of the canopy, and determine whether a portion of a mining machine will contact a portion of the canopy based on the signal. 
     In some aspects, when the controller determines that contact will occur, the controller is further configured to perform at least one of the following: operate an actuator to modify the position of the canopy, and generate an alert to an operator. 
     In some aspects, the signal is a first signal, and the controller is configured to receive a second signal indicative of at least one of a position of the mining machine and a path of the mining machine, the controller comparing the first signal to the second signal. 
     In some aspects, the controller determines that contact will occur if the controller determines that the portion of the mining machine will pass less than a predetermined minimum distance relative to the canopy. 
     In some aspects, the actuator is operable to extend and retract a link of the roof support, extension and retraction of the actuator causing the canopy to move. 
     In some aspects, the link is coupled between a base of the roof support and a shield coupled to the canopy. 
     In yet another independent aspect, a method for controlling operation of a roof support includes: generating a first signal indicative of a position of a canopy of the roof support; and determining whether a portion of a mining machine will contact a portion of the canopy based on at least the first signal. 
     In some aspects, the method further includes generating a second signal indicative of at least one of a position of the portion of the mining machine and a path of the portion of the mining machine, and determining whether the portion of the mining machine will contact the portion of the canopy is based on the first signal and the second signal. 
     In some aspects, the method further includes, when the controller determines that contact will occur, operating an actuator to modify a position of the canopy. 
     In some aspects, operating the actuator includes changing a length of a telescopic link, thereby causing the canopy to move away from a mine face. 
     In some aspects, the method further includes, when the controller determines that contact will occur, generating an alert to notify an operator. 
     In some aspects, determining whether the portion of the mining machine is likely to contact the portion of the canopy includes determining whether the portion of the mining machine will pass within a minimum predetermined distance of the canopy. 
     Other independent aspects of the disclosure will become apparent by consideration of the detailed description, claims, and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a mining system. 
         FIG.  2    is an enlarged perspective view of the mining system of  FIG.  1   . 
         FIG.  3    is a perspective view of a roof support. 
         FIG.  4 A  is a side view of a roof support with a canopy in a first position. 
         FIG.  4 B  is a side view of the roof support of  FIG.  4 A  with the canopy in a second position. 
         FIG.  5    is a diagram of a system for controlling operation of a roof support. 
         FIG.  6    is a flowchart of a method for controlling operation of a roof support. 
     
    
    
     Before any embodiments are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Also, electronic communications and notifications may be performed using any known means including direct connections, wireless connections, etc. 
     In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, aspects may be implemented in software (for example, stored on non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor, an application specific integrated circuits (“ASICs”), or another electronic device. As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components may be utilized. For example, “controllers” described in the specification may include one or more electronic processors or processing units, one or more computer-readable medium modules, one or more input/output interfaces, and various connections (for example, a system bus) connecting the components. 
     DETAILED DESCRIPTION 
     The disclosure generally relates to a longwall mining system including a roof support having extendable links. In some embodiments, the links may be telescoping, adjusting the distance between a canopy of the roof support and a mine face. In some embodiments, the extension of the links may be controlled to modify a position of a canopy to avoid a potential collision. 
       FIGS.  1  and  2    illustrate a longwall mining operation. A mining machine  10  excavates material from a mine face  14  of a mineral seam  18 , and progresses through the seam  18  as material is removed. In the illustrated embodiment, the mining operation is “retreating” such that the shearer  10  progresses through the seam  18  toward a mine exit (not shown). In other embodiments, the operation may be “advancing” such that the shearer  10  progresses through the seam  18  away from the mine exit. 
     In the illustrated embodiment, the mining machine  10  is a conventional longwall shearer that moves or trams along the mine face  14 . As shown in  FIG.  2   , the mining machine  10  includes one or more cutting heads, such as rotating cutting drums  20 , including cutting bits  22  that engage the mine face  14  and cut material from the mine face  14 . Each drum  20  may include vanes (not shown) for carrying the cut material from the face  14  toward a rear end of the drum  20 , where the material is deposited onto a face conveyor  30 . The face conveyor  30  moves the material toward an edge of the mine face  14 , where the cut material may be transferred to a main gate conveyor via a beam stage loader  38  ( FIG.  2   ). In some embodiments, the face conveyor  30  is a chain conveyor including flight bars coupled between multiple chain strands, and the conveyor drives material along a pan formed as interconnected sections. Other aspects of the structure and operation of the machine  10  and the conveyor  30  will be readily understood by a person of ordinary skill in the art. 
     As shown in  FIGS.  1  and  2   , powered roof supports  42  are aligned in a row along the length of the mine face  14  to provide protection to operators as well as the components of the mining operation (e.g., the mining machine  10 , the face conveyor  30 ). For illustration purposes, some of the roof supports  42  are removed in  FIGS.  1  and  2   . 
     Referring now to  FIG.  3   , each roof support  42  includes a base  24 , a canopy  26 , and actuators, or jacks,  28  extending between the base  24  and the canopy  26 . The base  24  is positioned on a support surface or floor  66  ( FIG.  2   ) and is coupled to the face conveyor  30  by a linear actuator  16  (e.g., a hydraulic cylinder or ram). As the mining operation progresses, the roof supports  42  and face conveyor  30  may advance to maintain a desired position with respect to the mine face  14  ( FIG.  2   ). In some embodiments, each of the sections of the conveyor pan is coupled to the base  24  of an associated one of the roof supports  42 . The linear actuator  16  may extend to advance the associated section of the conveyor pan. 
     The canopy  26  is positioned adjacent a hanging wall or mine roof (not shown). Each roof support  42  includes a shield  32  coupled between a rear end  24   a  ( FIG.  4 A ) of the base  24  and a rear end  26   a  of the canopy  26 . The shield  32  and the base  24  are pivotably coupled to one another by multiple links. Referring to  FIGS.  3 ,  4 A, and  4 B , first links or upper links or forward links  34  are coupled between the shield  32  and the base  24 , and second links or lower links or rearward links  36  are coupled between the shield  32  and the base  24 . As best shown in  FIG.  3   , the forward links  34  include a pair of links spaced apart from one another along the width of the roof support  42 . The forward links  34  are positioned between the rearward links  36  and the mine mine face  14 . The forward links  34  and rearward links  36  (sometimes referred to as lemniscate links) provide stability for the roof support  42  in the face-to-goaf direction and facilitate transmission of torque loads T ( FIG.  3   ) from the canopy  26  and shield  32  to the base  24 . Torque loads T may be caused, for example, by uneven roof surfaces. 
     As shown in  FIGS.  4 A and  4 B , the forward links  34  are extendable to permit adjustment of the position of the canopy  26  by adjusting a tip-to-face clearance D. In the illustrated embodiment, each of the forward links  34  includes a box link  40  with telescoping portions, and a linear fluid actuator  44  (e.g., a hydraulic cylinder or ram) is positioned inside the telescoping portions and is operable to extend and retract the ends of the box link  40 . The box links  40  facilitate the transmission of the torque load(s) T to the base  24 , while also protecting the actuators  44 . In the illustrated embodiment, the default or normal operating position for the forward links  34  is a retracted position. Since the forward links  34  are typically subjected to compressive loads, the forward links  34  therefore perform similar to conventional links while fully retracted. 
     As shown in  FIG.  5   , in some embodiments the system  100  includes one or more sensors  110  for detecting a position of the canopy  26  ( FIG.  4 A ). The sensor(s)  110  may include, for example, a transducer positioned within the actuators  44 . The sensor  110  is in communication with a controller  114 . In some embodiments, the controller  114  also has access to information regarding the geometry of at least a portion of the roof support  42  (e.g., the canopy  26 ) and at least a portion of the mining machine  10  (e.g., the cutting heads  20 ). For example, this information may be provided by one or more sensors, or may be stored in an electronic memory unit that is in communication with an electronic processor. Also, in some embodiments, additional sensors  112  may detect a path and/or a position of the cutting heads  20  of the mining machine  10 . 
     In some embodiments, the sensors may provide positioning data to the controller  114  in order verify and validate the presence of convergence or developing cavities within the mine face  14 . In addition, sensors in the actuators  44  can provide additional position data and assist in identifying potential convergence or developing cavities. 
     The controller  114  determines whether the mining machine  10  will contact or strike a portion of the canopy  26  based on the detected position information. In some embodiments, the controller  114  can operate the actuators  44  to move the forward links  40  and modify the position of the canopy  26  to avoid collision. In some embodiments, the control system may alert an operator of a potential collision between the mining machine  10  and the canopy  26 .  FIG.  6    illustrates a control method  200  according to one example. In the illustrated embodiment. The method includes generating (for example, with the sensor  110 ) a first signal indicative of a position of the canopy  26  at  210 , and generating (for example, with another sensor or from electronic memory) a second signal indicative of a position and/or a path of the cutting head of the mining machine  10  at  220 . The controller  114  is configured to determine at  230  whether the cutting head will collide with the canopy  26  based on the first signal and the second signal. In some embodiments, this determination may include determining whether the cutting head  20  will pass within a predetermined minimum distance relative to the canopy  26 . At  240 , when the controller  114  determines that a collision will occur, the controller  114  can operate the actuators  44  to modify the position of the canopy  26  and/or alert an operator to modify the canopy position. 
     Referring against to  FIG.  4 A , the roof support  42  is positioned proximate a face  14  with the forward links  34  in a retracted position. A distance between a forward end of the canopy  26  and the mine face  14  defines the tip-to-face clearance D. An operator can adjust the tip-to-face clearance D by adjusting the length of the forward links  34 . The ability to increase the clearance D can improve the versatility of the roof support  42  and avoid the need to implement complex tip designs for the forward edge of the canopy  26 . 
     For example, if additional space is required between the canopy  26  and the face  14  (e.g., in order to permit a shearer drum to perform a cut along the top of the face), the linear actuators  44  may be operated to extend the forward links  34 . As shown in  FIG.  4 B , the extension of the forward links  34  pivots the shield  32  rearwardly about the rear link  36 , moving the canopy  26  away from the face  14 . In the illustrated embodiment, when the forward links  34  are in the extended positions, the tip-to-face clearance D is increased. Increasing the clearance D can permit a shearer to pass the canopy  26 , after which the forward links  34  can be actuated to move the canopy  26  back to the extended position. When a sensor detects a potential collision, an operator or an automatic controller activates the actuators  44 , moving the forward links  34  to pivot the shield  32  and provide clearance between the shearer  10  and the canopy  26 . 
     The extendable forward links  34  support the canopy  26  while also permitting the position of the canopy to be adjusted as necessary. As shown in  FIGS.  4 A and  4 B , in some embodiments, the forward link  34  can be extended or retracted while substantially maintaining a distance B between the base  24  and the mine face  14 , and maintaining a height H of the support surface of the canopy  26 . 
     In some conventional systems, potential collisions between the roof support  42  and the shearer  10  are avoided by halting the shearer  10  and lowering the drums  20  and/or moving the roof supports  42  away from the face, into a goaf. Lowering the drums  20  may lead to developing steps in the roof and closing the face, making advancement more difficult, and moving the entire roof support  42  away from the face can be cumbersome. In contrast, a control system of the roof support  42  can anticipate and automatically prevent a collision. By increasing the tip-to-face clearance D, the user may remove a tip of the canopy out of the collision course without lowering the drum  20 . 
     Also, in some circumstances (e.g., in the presence of poor roof conditions), an operator may perform a second or intermediate advance of the roof support  42  (sometimes referred to as “double chocking”), advancing the roof support by a shorter incremental distance to avoid advancing the roof support too far such that it blocks the path of the shearer. Such incremental advances require moving the roof supports significantly more times and lead to longer cycle times. In contrast, the ability to increase the tip-to-face clearance D permits an operator (at least in some situations) to operate a normal first advance and second advance without the need for an incremental advance, thereby decreasing cycle times and increasing the overall efficiency of the mining operation. 
     Although various aspects have been described in detail with reference to certain embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects as described. Various features and advantages are set forth in the following claims.