Complete specification Surface miner Kerb flushing

Field of Invention:

The present invention relates to an improvement in the surface mining equipment which aids in better mining plan and leading to higher production, more particularly to a hydraulic retractable auxiliary cutter which acts synchronously with the main cutter, to flush the kerb formed on the mechanical belt drive side of the surface mining tool.

Background of the Invention:

Surface mining is used to extract minerals and metals which are near the surface of the Earth and it includes all or any part of a process followed in the production of minerals from the earth or from the surface of the land by surface excavation methods, such as open pit mining, dredging, placering, or quarrying. Surface miners are equipments or machines which are used to extract the minerals from the mine face with a mining tool fixed to a mobile frame. In surface miners the mining tool is attached to the frame and is driven with a drive train connected to a prime mover.

Surface miners are generally classified into three categories based on cutter power transmission driveline. First is the chain driven surface miners where the chain also has cutting tips fixed onto it which can penetrate into the material being cut. Second type uses a hydraulic motor or electric motor for the power transmission, the hydraulic/ electric is directly fixed to the cutter drive by means of with or without a gear box. Third category uses a mechanical belt drive arrangement for power transmission. The mechanical belt drive arrangement connecting the mining tool to the prime mover projects out of the maximum cutting width of the mining tool. In case of chain driven surface miners the cutter drum inertia cannot be used while cutting because the drive is positive and drive cannot slio or over speed.

In the second case, it is economically feasible only for smaller applications and in case of larger equipments it becomes totally in viable. In case of first and second arrangements projections beyond the cutter assembly can be easily avoided but in case of a mechanical belt drive arrangement the projection beyond the width of the cutter assembly is unavoidable. The mechanical belt drive arrangement provides the following advantages over the others by permitting over speeding thus allowing the cutter drum to use its inertia, it enables quick assembly and disassembly, less noisy, better handling and very economical. Because of these advantages, in many types of equipment belts drive assembly are being employed. Nevertheless it has its own limitations as mentioned earlier that is the projection beyond the cutter assembly. This projection leads to the formation of a kerb which is detrimental to the production activity. This projection also demands a necessary clearance to be maintained between the edge of the cutter and the side wall when the drive line is facing the side wall in an opencast mine. The mining regulations will demand a maximum slope angle beyond which the walls become unstable but on the other hand reducing the slope angle will reduce the productivity because the mine will become narrower as we penetrate deeper with smaller side wall angles. Hence mining contractors try to maximize the side wall angle to the limit. So because of this kerb formation while cutting from the drive side which will be around 45-50 degree which is unacceptable, the mining contractors use repetitive maneuvering of the machine so that always the non drive side of the machine is facing the side wall when cutting at near proximity to the side wall. With this methodology although we are able to achieve the required side wall angles, we are losing productivity and energy because of additional maneuvers involved.

The present invention overcomes the above said problems by placing an additional
auxiliary cutter on the side of the main cutter drive which assists in cutting the kerb formed because of drive line projection on the main cutter. The present invention further provides a pivoted hydraulic cylinder arrangement for automatic engagement and disengagement of the auxiliary cutter to add to its safety. This will protect the auxiliary cutter arrangement from over loads and also helps in smooth loading pattern during engagement and disengagement.

Objective of the Invention:

The main objective of the present invention is to provide an auxiliary cutter arrangement for the surface miners to enable kerb flushing.

The second objective of the present invention is to provide a pivoted load sensing hydraulic cylinder arrangement for automatic engagement and disengagement of the auxiliary cutter to prevent overloading and thus ensuring safety of the auxiliary cutter arrangement.

The third objective of the present invention is to provide an auxiliary cutter arrangement to improve the production rate of the surface miner.

Another objective of the present invention is to provide, an auxiliary cutter arrangement with power saving capacity.

Brief description of the prior art:

WO2011156865A1 discloses a seafloor auxiliary mining tool used in seafloor mining system. The auxiliary cutting tool is configured to cut extremities of a seafloor deposit, it cuts down the peripheries of complex seafloor formations in order to present relatively flat and horizontal benches suitable for bulk mining. Cuttings produced by the auxiliary cutting tool are sized by sizing means, to ensure that the cuttings are of desired size. This auxiliary cutting tool relates to the underwater mining or seafloor mining system and is not related to surface mining

CN102953728A discloses a split type cutting device of a coal cutter comprising an auxiliary rocker arm, main rocker arm, and hydraulic cylinder which is articulated with the auxiliary rocker arm and the main rocker arm. This split type cutting device meets the desired small diameter rollers and pick the top volume undercover capacity requirements, to achieve thin coal seams. This split type cutting device is suitable for various types of thin or thinner coal seam cutters and improves their production efficiency.

US3333893A provides an earth strata differentiating device for mining and tunneling machines to distinguish between earth strata. The earth strata differentiating device comprises a rotary cutting head equipped with main cutting teeth and an auxiliary cutting teeth mounted on the rotary cutting head. The auxiliary cutting teeth are positioned to cut the perimeter of the hole generated by the main cutting teeth. This type of earth strata differentiating device is generally used in bore mining machine.

WO2001077987A1 provides an automated cutting system for cutting terrain into a hi-accuracy three-dimensional topographical model. The hi-accuracy three-dimensional cutting apparatus for topographic modeling is electronically coupled with a computer that executes instructions in the form of algorithms. The automated cutting system includes a plurality of cutting means with multiple cutters moving at different paths and speeds. The multiple cutters includes a primary cutter moving along a rough translation of the two-dimensional contour to remove unwanted material from the object, and an auxiliary cutter moving along the two- dimensional contour to cut fine details for the model. The auxiliary cutter is operatively positioned with the primary cutter so as to move along the two-dimensional contour in conjunction with the primary cutter. This invention purely relates to modeling of the terrain.

US3318638A discloses an improved mining apparatus with auxiliary cutters. The mining apparatus comprises a main cutter which is advanced into a mine face to remove the materials and in which the cutting and breaking means is operable about an axis that is transversely disposed with respect to the direction of advance of the mining apparatus. An auxiliary cutter is provided to enable the cutting and breaking operations across the full width of the mining apparatus. In this invention, the main cutter and the auxiliary cutter are both driven in such a manner so as to satisfy the power requirements for achieving mining operation with full Width mining apparatus.

US3362753A discloses a mining apparatus to provide a new and improved means for forming a roof in an underground passageway and for removing cusps formed by a separate primary cutting means. The auxiliary cutter which is either elongated or cylindrical is suitably mounted on the outer surface of the apparatus for removing the upper cusps and for cutting additional clearance in the roof of the mine passageway.

All of the above mentioned auxiliary cutter systems are used in different kind of operations such as seafloor mining, split type cutting to make thin seams, earth strata differentiation, full width cutting etc. None of the auxiliary cutter system is used for kerb flushing function which is very essential for belt drive surface miners to increase the usable foot print of the surface mining equipment and to improve their production efficiency. The present invention eliminates the drawbacks of existing systems by placing an additional auxiliary cutter on the side of the main cutter drive for flushing the kerb formed on the belt drive side due to drive line projection on the main cutter. The pivot hydraulic cylinder arrangement with load sensing capacity enables automatic engagement and disengagement of the auxiliary cutter system to prevent the system from overloading and also helps in smooth loading pattern during engagement and disengagement.

Summary of the invention:

The present invention provides an auxiliary cutter on the side of the main cutter drive for flushing the kerb formed on the belt drive side due to drive line projection on the main cutter. The auxiliary cutter acts synchronously with the main cutter and can be mounted either on the leading or trailing side of the mechanical belt drive surface miners, for flushing the kerb. The surface mining tool assembly comprising a auxiliary cutter assembly; main cutter driven by the mechanical belt drive assembly; and a hydraulic cylinder attached to the auxiliary cutter. The pivot hydraulic cylinder arrangement with load sensing capacity enables automatic engagement and disengagement of the auxiliary cutter system to prevent the system from overloading and also helps in smooth loading pattern during engagement and disengagement.

This system helps in automating the whole process and will help in safeguarding the components from overload. The load sensing function of the hydraulic cylinder arrangement is sufficiently designed so as enable immediate retraction of the auxiliary cutter assembly during overload and immediate reengagement of the auxiliary cutter for kerb cutting under safe working pressure. Attaching auxiliary cutter either trailing or leading the mechanical belt drive arrangement enables the surface miners to work on the mine bench wall without the need for reorienting or repositioning the machine thus saving time and increasing the productivity of the system.

Brief description of the drawing:

Fig 1 shows the partial representation of the auxiliary cutter arrangement.

Fig 2 shows the detailed cross sectional view of the auxiliary cutter and its components.

Fig 3 represents the schematic flow chart illustrating the functioning of the load sensing system.

Fig 4 illustrates the bearing support side of the mining tool being used to cut the wall edges.

Fig 5 illustrates the mechanical belt drive side of the mining tool being used to cut the wall edges.

Detailed description of the invention with respect to drawing:

The present invention provides an auxiliary cutter mounted either on the leading or trailing side of the mechanical belt drive surface miners, for flushing the kerb formed due to the drive line projection on the main cutter. The auxiliary cutter acts synchronously with the main cutter, to flush the kerb thus providing additional cutting width and avoiding formation of a kerb on the mechanical belt drive side of the mining tool. The present invention also provides a pivoted load sensing hydraulic cylinder arrangement for automatic engagement and disengagement of the auxiliary cutter system to prevent overloading and to add safety to the cutter arrangement"'

Construction of the auxiliary cutter arrangement:

Fig 1 represents the mining tool assembly comprising a hydraulic driven auxiliary cutter drive assembly (12), mounted on a bracket (13) on the mining tool housing (14); main cutter (15) which is driven by the mechanical belt drive assembly (16); and a hydraulic cylinder (17) attached to the auxiliary cutter (12).

The said auxiliary cutter assembly is (12) driven through a planetary gearbox (18) using a hydraulic motor (19) and the other end of the cutter assembly is mounted on a bearing housing (20) mounted on a shaft (21) connected to the auxiliary cutter housing (22).

In the preferred embodiment the hydraulic cylinder (17) is provided with a load sensing feature which senses the preset stalling pressure Ps on the auxiliary cutter and controls a valve to retract the cylinder until the cutter pressure is lowered to a preset safe working value Pa. The hydraulic cylinder pressure will automatically start pushing back the auxiliary cutter adjacent to the main cutter to position 23 unless and until stalling pressure Ps appears in the system. This system helps in automating the whole process and will help in safeguarding the components from overload. FIG 3 shows the basic flow chart of the load sensing function of the hydraulic circuit. First the load sensing module (24) senses the stalling pressure of the auxiliary cutter Ps (25) and is compared with the preset safe working pressure value Pa (26) which is loaded in the hydraulic cylinder in advance.

When the sensed auxiliary cutter stalling pressure is found below the preset safe working pressure the hydraulic cylinder valve is extended to operate the auxiliary cutter (27) for kerb flushing. Whereas when the sensed auxiliary cutter stalling pressure is higher than the preset safe working pressure the hydraulic cylinder valve is retracted (28) and stops the working of auxiliary cutter assembly from kerb flushing function.

In the preferred embodiment the load sensing function of the hydraulic cylinder arrangement should be sufficiently designed so as enable immediate retraction of the auxiliary cutter assembly during overload and immediate reengagement of the auxiliary cutter for kerb cutting under safe working pressure.

In the preferred embodiment the pivoted arrangement connected to the hydraulic cylinder enables the automatic engagement and disengagement of the auxiliary cutter to maintain the same machine speed simultaneously ensuring the safety of the auxiliary cutter

Due to the projection of the mechanical belt drive (16) out of the housing of the mining tool (14), a kerb is formed below the mechanical belt drive (16). During such operation near the wall of the mine bench (29), this kerb formation will lead to very low bench angles which will lead to very low material extraction. To overcome this generally the bearing support side (30) of the mining tool is used when the machine is working very near to the walls of the mining benches as shown in FIG 4. In case if the drive side (31) of the machine comes to mine bench wall (29) as shown in FIG 5, the machine has to be repositioned so that the bearing support side (29) faces the mine bench wall (28). This will take considerable amount of time in case of larger bench surfaces. Attaching an additional auxiliary cutter (12) either trailing or leading the mechanical belt drive arrangement (16) eliminates the above problem.

The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without denartintr from the snirit of the nresent invention.

We Claim:

1) A mining tool assembly comprising: an auxiliary cutter with kerb flushing function mounted on a bracket of the mining tool housing; main cutter driven by the mechanical belt drive assembly; and a cylinder attached to the auxiliary cutter.

2) The mining tool assembly as claimed in claim 1, wherein the said auxiliary cutter acts synchronously with the main cutter, to flush the kerb formed under the belt drive due to the drive line projection on the main cutter.

3) The mining tool assembly as claimed in claim 1, wherein the said auxiliary cutter can be installed either on the leading or trailing side of the mechanical belt drive surface miners, for flushing the kerb formed under the belt drive.

4) The mining tool assembly as claimed in claim 1, wherein the said auxiliary cutter can be driven either with Hydraulic, Mechanical, electrical or Pneumatic drives.

5) The mining tool assembly as claimed in claim 1, wherein the said cylinder is provided with load sensing function for automatic engagement and disengagement of the auxiliary cutter system.

6) The mining tool assembly as claimed in claim 1, wherein the said cylinder with multiple freedom degrees and load sensing arrangement instantaneously reacts to the overload by automatically disengaging the auxiliary cutter assembly.

7) The mining tool assembly as claimed in claim 1, wherein the said cylinder with multiple freedom degrees and load sensing arrangement adjusts itself to angles required at different positions of the auxiliary cutter

8) The mining tool assembly as claimed in claim 1, wherein the said cylinder with multiple freedom degrees and load sensing arrangement instantaneously reengages the auxiliary cutter until it either reaches the maximum position or the pressure of the cylinder driving the cutter reaches to pre-set limit.

9) The mining tool assembly as claimed in claim 1, can work adjacent to the bench wall with either sides of the surface miner facing the bench, thus eliminating the need for reorienting or repositioning the machine this saves time and improves the machine productivity.