TECHNICAL FIELD
The present disclosure relates to a temporary roof support system, and more specifically, to a system for mounting a crossbar of the temporary roof support system.
BACKGROUND
Roof bolting is a common process to stabilize roofs in underground coal mines, tunnels and power plants. It involves inserting conventional cable or resin bolts by drilling directly into the rock strata using a roof bolter machine. The roof bolter machine generally includes a temporary roof support system for installing multiple bolts simultaneously in a roof to make it self-supporting. Typically, the temporary roof support system includes a crossbar mounted on a multistage telescopic cover assembly of a hydraulic cylinder. When the roof bolter machine travels in a mine or installs bolts in the roof, the crossbar of the temporary roof support system may be subjected to an unwanted side collision from rock strata of the roof. Such a side collision produces a large moment of force about central axis of the crossbar and has the ability to damage components of the temporary roof support system including the hydraulic cylinder and the multistage telescopic cover assembly.
The temporary roof support system generally uses a rigid bolted connection to support the crossbar on the multistage telescopic cover assembly of the hydraulic cylinder. The bolts in the rigid connection are designed to shear under force of the unwanted side collision so as to prevent transfer of side load from the crossbar to other components of the temporary roof support system. However, in such a design, if the force of the side collision is too less to shear the bolts, the bolts transfer the side load to the multi stage telescopic cover assembly of the temporary roof support system, thereby increasing the chances of failure of the multistage telescopic cover assembly or hydraulic cylinder. Also, some of the bolts may bend that are difficult to identify and replace, which results in increased downtime of the roof bolter machine. Further, an operator is required to manually inspect the temporary roof support system after every side collision so as to check for damaged components. Therefore, in current designs, complete isolation of load transfer from the crossbar to the other components of the temporary roof support system is not possible irrespective of the magnitude of the side load. Thus, there exists a need for a system for mounting the crossbar on the multistage telescopic cover assembly that completely isolates the load transfer from the crossbar to the other components of the temporary roof support system, and a system is also needed to protect the multistage telescopic cover assembly and the hydraulic cylinder from damage caused by a side collision.
SUMMARY OF THE DISCLOSURE
In one aspect of the present disclosure, a system for mounting a crossbar of a temporary roof support system is provided. The system for mounting the crossbar of the temporary roof support system having a multistage telescopic cover assembly includes a first assembly coupled to the crossbar of the temporary roof support system. The first assembly includes a first plate having a first surface, a second surface opposite to the first surface, the first plate is coupled to the crossbar at the second surface. The first assembly further includes a first hollow cylindrical structure attached to the first plate on the first surface. The first hollow cylindrical structure is provided with at least one first hole and at least one slot, each extending from an inner surface to an outer surface of the first hollow cylindrical structure. The first assembly further includes a first pin coaxially aligned with the first hollow cylindrical structure, and is attached to the first plate. The system includes a second assembly which is coupled to the multistage telescopic cover assembly. The second assembly includes a second plate having a third surface, a fourth surface opposite to the third surface, the second plate is coupled to the multistage telescopic cover assembly at the fourth surface. The second assembly further includes a second hollow cylindrical structure attached to the second plate on the third surface. The second hollow cylindrical structure is provided with at least one second hole and at least one third hole, each extending from an inner surface to an outer surface of the second hollow cylindrical structure. The second assembly further includes a pin hole which is coaxially aligned with the second hollow cylindrical structure, and the pin hole is adapted to accommodate the first pin. An outer diameter of the first hollow cylindrical structure is less than an inner diameter of the second hollow cylindrical structure, and the first hollow cylindrical structure mates with the second hollow cylindrical structure. At least one second pin extending through corresponding the at least one second hole of the second hollow cylindrical structure and the at least one first hole of the first hollow cylindrical structure. At least one third pin extending through corresponding the at least one third hole of the second hollow cylindrical structure and the at least one slot of the first hollow cylindrical structure.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a roof bolter machine having a temporary roof support system, in accordance with the concepts of the present disclosure;
FIG. 2 is a perspective view of a first assembly and a second assembly, in accordance with the concepts of the present disclosure;
FIG. 3 is a perspective view of the second assembly, in accordance with the concepts of the present disclosure;
FIG. 4 is an exploded view of the first assembly and the second assembly, in accordance with the concepts of the present disclosure;
FIG. 5 is a perspective view of a system having the first assembly and the second assembly, in accordance with the concepts of the present disclosure; and
FIG. 6 is a sectional view of the system having the first assembly and the second assembly taken along a sectional line 2-2′ of FIG. 5, in accordance with the concepts of the present disclosure.
DETAILED DESCRIPTION
Referring to FIG. 1, a roof bolter machine 10 includes a rear frame 12, a main frame 14, a drilling station 16, a drilling boom 18, and a temporary roof support system 20. The roof bolter machine 10 includes various other components such as, but not limited to, wheels, boom cylinder, stage cylinder etc. For the purpose of simplicity, the various other components of the roof bolter machine 10 are not labeled in FIG. 1. The temporary roof support system 20 is used for installing multiple bolts in a roof to make the roof self supporting. The temporary roof support system 20 includes a system 22, a base 24, a multistage telescopic cover assembly 26, a crossbar 28 with a first rocker pad 30 and a second rocker pad 32 at either end of the crossbar 28. The system 22 is used for mounting the crossbar 28 on the multistage telescopic cover assembly 26. During the roof bolting operation by the roof bolter machine 10, the first rocker pad 30 and the second rocker pad 32 at either end of the crossbar 28 support the roof while the bolts are installed in the roof.
Referring to FIG. 2, the system 22 includes a first assembly 34 and a second assembly 36. The first assembly 34 is coupled to the crossbar 28, and the second assembly 36 is coupled to the multistage telescopic cover assembly 26 (shown in FIG. 1). The first assembly 34 includes a first plate 38 and a first hollow cylindrical structure 40. The first plate 38 has a first surface 42 and a second surface 44 opposite to the first surface 42. The first plate 38 is rectangular in shape, and has a predetermined thickness. The first hollow cylindrical structure 40 has an outer diameter D1. The first hollow cylindrical structure 40 is attached to the first surface 42 of the first plate 38. The first hollow cylindrical structure 40 is provided with at least one first hole 46 and at least one slot 48. Each of the at least one first hole 46 and the at least one slot 48, extends from an inner surface 50 to an outer surface 52 of the first hollow cylindrical structure 40. In an exemplary embodiment, as shown in FIG. 2, the first hollow cylindrical structure 40 is provided with one first hole 46 and two slots 48. Further, the first assembly 34 includes a first pin 54 which is coaxially aligned with the first hollow cylindrical structure 40, and is attached to the first plate 38. The first pin 54 extends along a vertical axis 1-1′ at a center of the crossbar 28. The first assembly 34 is coupled to the crossbar 28 by a first pair of mounting brackets 56, which is welded to the first plate 38 at the second surface 44. The first pair of mounting brackets 56 is coupled to the crossbar 28 by a pin 70. The crossbar 28 pivots about the pin 70. The detailed description of the second assembly 36 is described later in conjunction with FIG. 3.
Referring to FIG. 3, the second assembly 36 includes a second plate 58 having a third surface 60 and a fourth surface 62. The second assembly 36 further includes a second hollow cylindrical structure 72 on the third surface 60 which is located opposite to the fourth surface 62. The second plate 58 is rectangular in shape, and has a predetermined thickness. The second plate 58 is provided with holes 64 and fasteners 66 for a threaded connection (shown in FIG. 2) with the multistage telescopic cover assembly 26 (shown in FIG. 1). Further, the second assembly 36 includes a second pair of mounting brackets 68 (shown in FIG. 2) provided on the fourth surface 62 for a connection with a rod end of a multistage telescopic cylinder (not shown). The second hollow cylindrical structure 72 is coupled to the third surface 60 of the second plate 58. The second hollow cylindrical structure 72 is provided with at least one second hole 74 and at least one third hole 76. Each of the at least one second hole 74 and the at least one third hole 76, extends from an inner surface 78 to an outer surface 80 of the second hollow cylindrical structure 72. In the exemplary embodiment, as shown in FIG. 3, the second hollow cylindrical structure 72 is provided with one second hole 74 and two third holes 76. The second assembly 36 further includes a pin hole 82 provided on the second plate 58. The pin hole 82 is coaxially aligned with the second hollow cylindrical structure 72, and is adapted to accommodate the first pin 54. The outer diameter D1 of the first hollow cylindrical structure 40 is less than an inner diameter D2 of the second hollow cylindrical structure 72, and thus provides clearance to the first hollow cylindrical structure 40 to rotate inside the second hollow cylindrical structure 72.
Referring to FIGS. 2, and 4, the first assembly 34 is coupled to the second assembly 36 in order to mount the crossbar 28 (shown in FIG. 2) on the multistage telescopic cover assembly 26 (shown in FIG. 1). As discussed above, the first assembly 34 is coupled to the crossbar 28 by the first pair of mounting brackets 56 attached to the first plate 38 at the second surface 44. The first pair of mounting brackets 56 is provided with a number of holes 84 through which the pin 70 (shown in FIG. 2) is inserted to couple the first pair of mounting brackets 56 with the crossbar 28. When the first assembly 34 and the second assembly 36 are coupled, the first hollow cylindrical structure 40 of the first assembly 34 is disposed in the second hollow cylindrical structure 72 of the second assembly 36 with the outer surface 52 of the first hollow cylindrical structure 40 of the first assembly 34 mating with the inner surface 78 of the second hollow cylindrical structure 72 of the second assembly 36. The first hollow cylindrical structure 40 of the first assembly 34 and the second hollow cylindrical structure 72 of the second assembly 36 are coaxially disposed and the first pin 54 of the first assembly 34 is received in the pin hole 82 (shown in FIG. 3) of the second plate 58 of the second assembly 36. The first hole 46 of the first hollow cylindrical structure 40 aligns with the second hole 74 of the second hollow cylindrical structure 72. A second pin 86 extends through the second hole 74 of the second hollow cylindrical structure 72 and further through the first hole 46 of the first hollow cylindrical structure 40. A first block 88 retains the second pin 86 in position by holding a portion of the second pin 86 projecting out from the outer surface 80 of the second hollow cylindrical structure 72. The second pin 86 is welded to a first support member 90 which provides a large base to hold the second pin 86. The first block 88 is generally rectangular with an outer surface 92 (i.e., a flat outer surface 92) and an inner surface 94 (i.e., a curved inner surface 94) to match with the profile of the outer surface 80 of the second hollow cylindrical structure 72. The first block 88 is provided with a first aperture 96 that aligns with the second hole 74 of the second hollow cylindrical structure 72 to accommodate the second pin 86. The first block 88 is attached with the outer surface 80 of the second hollow cylindrical structure 72, and the second plate 58 by a welded connection. The first support member 90 is coupled to the first block 88 by a first bolt 98 that passes through a third aperture 100 of the first support member 90 and through a second aperture 102 of the first block 88. It will be apparent to one skilled in the art that there can be multiple second pins 86 corresponding to multiple second holes 74 and multiple first blocks 88 to retain multiple second pins 86 without departing from the scope of the disclosure
The third hole 76 of the second hollow cylindrical structure 72 aligns at a center of the slot 48 of the first hollow cylindrical structure 40. A third pin 104 extends through the third hole 76 of the second hollow cylindrical structure 72, and further through the center of the slot 48 of the first hollow cylindrical structure 40. A second block 106 retains the third pin 104 in position by holding a portion of the third pin 104 projecting out from the outer surface 80 of the second hollow cylindrical structure 72. The third pin 104 is welded to a second support member 108 which provides a large base to hold the third pin 104. The second block 106 is generally rectangular with an outer surface 110 (i.e., a flat outer surface 110) and an inner surface 112 (i.e., a curved inner surface 112) to match with the profile of the outer surface 80 of the second hollow cylindrical structure 72. The second block 106 is provided with a fourth aperture 114 that aligns with the third hole 76 of the second hollow cylindrical structure 72 to accommodate the third pin 104. The second block 106 is attached with the outer surface 80 of the second hollow cylindrical structure 72, and the second plate 58 by a welded connection. The second support member 108 is coupled to the second block 106 by a second bolt 116 that passes through a sixth aperture 118 of the second support member 108 and through a fifth aperture 120 of the second block 106. It will be apparent to one skilled in the art that there can be multiple third pins 104 corresponding to multiple third holes 76 and multiple second blocks 106 to retain multiple third pins 104, without departing from the scope of the disclosure.
Referring to FIGS. 5 and 6, during installation of the bolts in the roof of the mine, the crossbar 28 (shown in FIG. 2) of the temporary roof support system 20 may be subjected to an unwanted side collision. Such type of a side collision produces a large moment of force about the vertical axis 1-1′ at the center of the crossbar 28. The large moment of force produced by the side collision is transferred to the second pin 86 via the first hollow cylindrical structure 40 of the first assembly 34 which is connected to the crossbar 28 by the first pair of mounting brackets 56. The second pin 86 of the system 22 is adapted to shear due to the force produced by the side collision, when magnitude of the force exceeds a predetermined threshold. The second pin 86 is designed as the weakest link in the system 22, and is adapted to be weaker than the crossbar 28 so that the second pin 86 breaks before the crossbar 28 can break. The second pin 86 absorbs the collision force if magnitude of the collision force is less than shear strength of the second pin 86. The second pin 86 shears if magnitude of the collision force is greater than the shear strength of the second pin 86. When the second pin 86 shears, the crossbar 28 of the temporary roof support system 20 and the first assembly 34 are free to rotate in unison in clockwise (or anticlockwise) direction about the first pin 54 extending along the vertical axis 1-1′ at the center of the crossbar 28. The first hollow cylindrical structure 40 of the first assembly 34 is coupled to the crossbar 28 rotates inside the second hollow cylindrical structure 72 of the second assembly 36 until the slot 48 of the first hollow cylindrical structure 40 of the first assembly 34 comes into contact with the third pin 104. The third pin 104 is subsequently adapted to absorb the force produced by the side collision. The slot 48 provides restricted angular movement of the crossbar 28 during the side collision. This movement also acts as a visual indication to the operator to ascertain the breakage of the second pin 86 due to the collision force.
It will be apparent to one skilled in the art that the shape of the first plate 38 and the second plate 58 mentioned above have been provided only for illustration purposes. Alternatively, the shape of the first plate 38 and the second plate 58 such as, but not limited to, a trapezoidal, a polygon, or a circular, without departing from the scope of the disclosure.
INDUSTRIAL APPLICABILITY
Roof bolting is a common process to stabilize roofs in underground mines, tunnels and power plants. A roof bolter machine generally includes a temporary roof support system which includes a crossbar mounted on a multistage telescopic cover assembly of a hydraulic cylinder. The crossbar of the temporary roof support system may be subjected to an unwanted side collision during its operation, which has the ability to damage components of the temporary roof support system including the hydraulic cylinder and the multistage telescopic cover assembly.
Referring to FIG. 4, the present disclosure provides the system 22 for mounting the crossbar 28 (shown in FIG. 2) of the temporary roof support system 20. The second pin 86 of the system 22 does not shear if the strength of the force produced by the side collision is less than the shear strength of the second pin 86. During such instances, there is no need to replace the second pin 86 and all components of the temporary roof support system 20 are protected. The second pin 86 shears only if the magnitude of force produced by the side collision is greater than the shear strength of the second pin 86. When the second pin 86 shears, the crossbar 28 of the temporary roof support system 20 begins to rotate in clockwise or anticlockwise direction about the first pin 54 extending along the vertical axis 1-1′ at the center of the crossbar 28. The rotation of the crossbar 28 is a clear indication for the operator that the second pin 86 has sheared and must be replaced. The replacement of a new second pin 86 in the system 22 is easy, as broken portion of the previous second pin 86 remains inside the first hollow cylindrical structure 40. The new second pin 86 is installed by inserting it through the first aperture 96 in the first block 88 and further inserting it through the second hole 74 and the first hole 46 of the second hollow cylindrical structure 72 and the first hollow cylindrical structure 40 respectively. The system 22 needs not be opened every time the operator replaces the second pin 86. This reduces the downtime of the roof bolter machine 10, and need for an immediate halt of the operations of the roof bolter machine 10.
The system 22 provides for a complete isolation of load transfer from the crossbar 28 to the multistage telescopic cover assembly 26 and the multistage cylinder (not shown) disposed within the multistage telescopic cover assembly 26 irrespective of the magnitude of the side load. The system 22 further prevents the crossbar 28 from falling down after shearing of the second pin 86 when the third pin 104 stops the rotation of the slot 48 of the first hollow cylindrical structure 40 of the first assembly 34. Since the fast assembly 34 is coupled to the crossbar 28, the rotation of the crossbar 28 is also stopped and is held in position. The system 22 has a simple design and protects the components of the temporary roof support system 20 including the crossbar 28, the multistage cylinder (not shown), multistage telescopic cover assembly 26, and the base 24 from any damage caused by the side collision.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
Patent Application
20160146007
