초록 ▼

A large electric dragline having a housing (35) and boom (37) is provided with spaced apart in-line sheaves (34) and (36) at boom point to separate hoist ropes (31) and (32) which are led to the front and rear of bucket (30) respectively. Differential hoist rope control allows accurate and continuou

A large electric dragline having a housing (35) and boom (37) is provided with spaced apart in-line sheaves (34) and (36) at boom point to separate hoist ropes (31) and (32) which are led to the front and rear of bucket (30) respectively. Differential hoist rope control allows accurate and continuous adjustment of the bucket carry angle during all modes of operation. Also described is a computer control system giving continuous accurate control of carry angle by differential hoist rope operation, with manual selection of mode of operation.

대표청구항 ▼

The invention claimed is: 1. A large electric dragline of the type typically used for open cut mining operations comprising: a rotatable support mounted on a base; a boom assembly projecting outwardly from the support and rotatable therewith; a bucket suspended from a distal end of the boom assembl

The invention claimed is: 1. A large electric dragline of the type typically used for open cut mining operations comprising: a rotatable support mounted on a base; a boom assembly projecting outwardly from the support and rotatable therewith; a bucket suspended from a distal end of the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket; a rigging configuration providing first and second boom point sheaves located at or adjacent the distal end of the boom assembly and spaced apart one behind the other by a fixed distance such that the first sheave is located closer to the support than the second sheave; first and second hoist ropes entrained over the first and second boom point sheaves, the first hoist rope being entrained over the first sheave, extending downwardly and being operatively connected solely to a front section of the bucket, the second hoist rope being entrained over the second sheave, extending downwardly and being operatively connected to a rear section of the bucket; and a control system using a computer to control the relative movement of the first and second hoist ropes via hoisting gear arranged to alter the angle of inclination of the bucket in a vertical plane by differential movement of one hoist rope relative to the other, to maintain the bucket in a desired angle of inclination for a mode of dragline operation selected by an operator. 2. A rigging configuration for a dragline having a rotatable support mounted on a base, a boom assembly projecting outwardly from the support and rotatable therewith, and a bucket suspended from a distal end of the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket, the rigging configuration providing at least first and second boom point sheaves located at or adjacent the distal end of the boom assembly and spaced apart one behind the other by a fixed distance such that the first sheave is located closer to the support than the second sheave, first and second hoist ropes entrained over the first and second boom point sheaves, one to each, the first hoist rope being entrained over the first sheave, extending downwardly and being operatively connected solely to a front section of the bucket, the second hoist rope being entrained over the second sheave, extending downwardly and being operatively connected to a rear section of the bucket, and the at least one drag rope extending from the support and being operatively connected to the front section of the bucket. 3. A rigging configuration for a dragline as claimed in claim 2, wherein the first and second sheaves are spaced apart by a fixed distance of a similar order to the spacing of the operative connections of the first and second hoist ropes to the bucket. 4. A rigging configuration for a dragline as claimed in claim 2, wherein the first and second sheaves each have a medial plane extending from the mid point of the sheave perpendicular to the axis of rotation of that sheave, and wherein the medial planes the first and second sheaves lie substantially in a common vertical plane. 5. A dragline mining apparatus comprising: a rotatable support mounted on a base; a boom assembly projecting outwardly from the support and rotatable therewith the boom assembly having a boom having a length of about 100 meters; a bucket having a pay load capacity of about 90 tons and being suspended from the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket; and the rigging configuration of claim 1. 6. A dragline mining apparatus for open cut mining operations comprising: a rotatable support mounted on a base; a boom assembly projecting outward from the support and rotatable therewith; a bucket suspended from a distal end of the boom assembly by adjustable hoist ropes and controllable by at least one drag rope extending from the support to the bucket; the rigging configuration of claim 1; and a control system using a computer to control the relative movement of the first and second hoist ropes via hoisting gear arranged to alter the angle of inclination of the bucket in a vertical plane by differential movement of one hoist rope relative to the other, to maintain the bucket in a desired angle of inclination for a mode of dragline operation selected by an operator. 7. A dragline having a rigging configuration as claimed in claim 2 and further incorporating differential control for hoist rope payout and retrieval, arranged such that the length of one said hoist rope may be adjusted relative to the other said hoist rope to control the angle of inclination of the bucket in a vertical plane. 8. A dragline as claimed in claim 7 wherein one said hoist rope is wound on to a first drum located on the base, and the other said hoist rope is wound on to a second drum located on the base, the first and second drums being independently rotatable to achieve said differential control. 9. A dragline as claimed in claim 8 wherein said first and second drums are mounted adjacent one another on a common axis with their inner ends adjacent to one another. 10. A rigging configuration for a dragline as claimed in claim 2 wherein the first hoist rope is connected directly to an upper portion of the front section of the bucket, and the second hoist rope is connected directly to the rear section of the bucket, the at least one dragline being connected to the bucket at a position that is below and independent of the first hoist rope. 11. A rigging configuration for a dragline as claimed in claim 10 wherein the first hoist rope is connected to the mid point of an arch extending across the mouth of the bucket. 12. A rigging configuration for a dragline as claimed in claim 10 wherein the second hoist rope is connected to a top rail extending across a rear wall of the bucket. 13. A rigging configuration for a dragline as claimed in claim 10 wherein the second hoist rope is connected to the rear wall of the bucket at a point between the top rail of the rear wall and the base of the bucket, said point being located significantly below the top rail. 14. A control system for a dragline of the type having a rotatable support mounted on a base, a boom assembly projecting outwardly from the support and rotatable therewith, and a bucket suspended from a distal end of the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket, there being at least two adjustable hoist ropes of which the first is operatively connected to a front section of the bucket and the second is operatively connected to a rear section of the bucket, each hoist rope being actuated by hoisting gear arranged to alter the angle of inclination of the bucket in a vertical plane by differential movement of one hoist rope relative to the other, the control system using a computer to control the relative movement of the first and second hoist ropes via the hoisting gear, to maintain the bucket in a desired angle of inclination for a mode of dragline operation selected by an operator, wherein the dragline includes at least first and second boom point sheaves located at or near the distal end of the boom assembly, spaced apart one behind the other by a fixed distance such that the first sheave is located closer to the support relative to the second sheave, the first said hoist rope being entrained over the first sheave and the second said hoist rope being entrained over the second sheave. 15. A control system for a dragline as claimed in claim 14 wherein the modes of dragline operation selected by the operator can include any one or more of chopping, digging, disengaging, carrying, dumping and cleaning modes. 16. A dragline mining apparatus comprising: a rotatable support mounted on a base; a boom assembly projecting outwardly from the support and rotatable therewith, said boom assembly having a length of about 100 meters; a bucket having a payload capacity of about 90 tons and being suspended from the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket; and the control system of claim 14. 17. A control system for a dragline as claimed in claim 14 wherein, in one or more of the selected modes of operation, the computer controls the desired angle of operation continuously throughout that mode. 18. A control system for a dragline as claimed in claim 17 wherein said one or more selected modes of operation comprises multiple modes including digging, carrying, and cleaning modes. 19. A control system for a dragline as claimed in claim 14 wherein the computer is used to limit the rates of dynamic transition that the hoisting gear may apply. 20. A control system for a dragline as claimed in claim 19 wherein the dynamic transition occurs during a change in the mode of operation. 21. A control system for a dragline as claimed in claim 14 wherein the control system is arranged to allow the operator to control movement of the bucket relative to the boom assembly and housing. 22. A control system for a dragline as claimed in claim 21 wherein the control system is arranged to allow the operator to control movement of the bucket relative to the boom assembly and housing only within preset safe operating parameters. 23. A rigging configuration for a dragline having a rotatable support mounted on a base, a boom assembly projecting outwardly from the support and rotatable therewith, and a bucket suspended from the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket, the rigging configuration providing at least first and second boom point sheaves located at or adjacent the distal end of the boom assembly and spaced apart one behind the other by a fixed distance such that the first sheave is located closer to the support than the second sheave, first and second hoist ropes entrained over the first and second boom point sheaves, one to each, the first hoist rope being entrained over the first sheave, extending downwardly and being operatively connected to a front section of the bucket, the second hoist rope being entrained over the second sheave, extending downwardly and being operatively connected to a rear section of the bucket, such that in use, orientation of the bucket in a vertical plane can be controlled to maintain the bucket in a desired angle of inclination for a mode of dragline operation selected by an operator, and the at least one drag rope extending from the support and being operatively connected to the front section of the bucket. 24. A rigging configuration for a dragline as claimed in claim 23, wherein the first and second sheaves are spaced apart one behind the other by a fixed distance of a similar order to the spacing of the operative connections of the first and second hoist ropes to the bucket. 25. A rigging configuration for a dragline as claimed in claim 23, wherein the first and second sheaves each have a medial plane extending from the mid point of the sheave perpendicular to the axis of rotation of that sheave, and wherein the medial planes the first and second sheaves lie substantially in a common vertical plane. 26. A rigging configuration for a dragline as claimed in claim 23 wherein the first hoist rope is connected directly to a front section of the bucket, and the second hoist rope is connected directly to a rear section of the bucket, without the use of intervening rigging such as spreader bars or trunnions. 27. A rigging configuration for a dragline as claimed in claim 26 wherein the second hoist rope is connected to the rear wall of the bucket at a point between the top rail of the rear wall and the base of the bucket, said point being located significantly below the top rail. 28. A dragline mining apparatus comprising: a rotatable support mounted on a base; a boom assembly projecting outwardly from the support and rotatable therewith; a bucket suspended from the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket; and the rigging configuration of claim 23. 29. A dragline having a rigging configuration as claimed in claim 23 and further incorporating differential control for hoist rope payout and retrieval, arranged such that the length of one said hoist rope may be adjusted relative to the other to control the angle of inclination of the bucket in a vertical plane. 30. A dragline as claimed in claim 29 wherein one said hoist rope is wound on to a first drum located on the base, and the other said hoist rope is wound on to a second drum located on the base, the first and second drums being independently rotatable to achieve said differential control. 31. A dragline as claimed in claim 30 wherein said first and second drums are mounted adjacent one another on a common axis with their inner ends adjacent to one another. 32. A rigging configuration for a dragline as claimed in claim 26 wherein the first hoist rope is connected to the mid point of an arch extending across the mouth of the bucket. 33. A rigging configuration for a dragline as claimed in claim 26 wherein the second hoist rope is connected to a top rail extending across a rear wall of the bucket.