Background of the Invention

[0001] The present invention relates to an elevating apparatus for moving equipment along a predetermined non-linear trajectory, and in one example to an elevating apparatus for moving a work platform along an arcuate trajectory about an exterior surface of a grinding mill.

Description of the Prior Art

[0002] Sacrificial liners are secured to the internal casing of ore grinding mills. They are typically provided as segments, and they are secured internally of the mill shell by bolts which are fitted from the internal side of the shell and project through apertures in the liners and through mounting bores in the shell. A nut and sealing washer are threaded onto and tightened onto each bolt from outside the shell, drawing the liner to the inner surface of the shell. An example of a conventional liner segment fastener system is shown in US 4,018,393. Typically the bolts used for such application are referred to as linerbolts.

[0003] Ore mills are generally run continuously for economic efficiency. The continuous process wears down the liners over a period of time, which will depend on the type of ore and application, after which the liners will have to be replaced. Because down time of the ore mill adversely affects the economic efficiency of the process, it is essential to replace liners as quickly as possible. Liner replacement involves removal of nuts, typically followed by removal of the bolt by hammering the exposed bolt from the outside of the mill.

[0004] In such applications, the bolts on liners become corroded and clearances between bolts and holes become compacted with ore fines. This results in difficult bolt removal. As a result the many bolts that are utilised to attach the liners to the mill shell are often required to be freed manually by the use of large sledge-hammers, and more frequently by percussive devices such as jack-hammers and hydraulically powered hammers to provide repetitive impacts.

[0005] The process of mill relining commonly requires personnel to access the curved outer wall of the grinding mill to remove and then reinstall mill linerbolts and nuts. In order to perform this process an elevating platform may be used to lift and lower personnel to the correct height so as to access the linerbolts. A conventional elevating work platform operates with a linear motion and creates the issue of having a variable gap between the platform and the outer surface of the mill. The variable gap creates problems for ensuring the safety of personnel by preventing possible falls or crush points. Previously this problem has been dealt with by using an extending portion of platform but this means complicated mechanisms and an increase in moving parts. A platform that moves around the profile of the outer shell is desirable in the interest of reducing moving parts and improving safety.

[0006] WO2016/176739 describes an apparatus for suspending and guiding at least one tool or work platform externally about a grinding mill, the apparatus including (a) a fixed track suspended above the grinding mill and extending about an outer periphery thereof in a plane substantially parallel to a surrounding floor of the mill, and, (b) at least one carriage assembly mounted to the track for suspending and guiding the at least one tool or work platform, the at least one carriage assembly configured to provide the at least one tool or work platform with at least two degrees of freedom, and wherein a first degree of freedom is linear movement along a first axis orthogonal to the surrounding floor of the mill.

[0007] However, the solution of WO2016/176739 is significantly more complex and expensive compared to a traditional elevating work platform, and a solution of intermediate complexity and cost is desirable in some applications.

[0008] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Summary of the Present Invention

[0009] In one broad form an aspect of the present invention seeks to provide an elevating apparatus for moving equipment along a predetermined non-linear trajectory while an equipment reference plane is maintained in a constant orientation relative to a stationary reference plane, the apparatus including: a moveable carriage for supporting the equipment, the carriage including a first restraint point, and a second restraint point that is offset from the first restraint point by an offset vector; and first and second tracks that are fixed relative to the stationary reference plane, the first and second tracks defining respective first and second paths each corresponding to the non-linear trajectory, the second path being translated relative to the first path by the offset vector, and the carriage being mounted to the first and second tracks so that the first restraint point follows the first path and the second restraint point follows the second path during movement of the carriage relative to the first and second tracks.

[0010] In one embodiment the stationary reference plane is a horizontal ground plane.

[0011] In one embodiment the first and second tracks define the first and second paths in respective parallel planes extending perpendicularly from the horizontal ground plane.

[0012] In one embodiment the non-linear trajectory is defined relative to a non-linear surface of an object.

[0013] In one embodiment the non-linear trajectory is defined to maintain a constant separation distance between a predetermined point on the equipment and the non-linear surface of the object.

[0014] In one embodiment the object is a grinding mill, such that the non-linear trajectory is defined relative to an exterior surface of the grinding mill.

[0015] In one embodiment the non-linear trajectory is an arcuate trajectory corresponding to a curvature of the exterior surface of the grinding mill.

[0016] In one embodiment the first and second paths define respective first and second circular arcs having the same radius and respective first and second centre points, the second centre point being translated relative to the first centre point by the offset vector.

[0017] In one embodiment the apparatus includes a frame that is fixed relative to the stationary reference plane, the first and second tracks being supported by the frame.

[0018] In one embodiment the carriage includes respective rollers at each of the first and second restraint points, each roller being guided by a respective one of the first and second tracks. [0019] In one embodiment the first and second tracks are curved channels configured to receive the respective rollers and guide the rollers along the respective first and second paths.

[0020] In one embodiment the apparatus includes two or more parallel first tracks and two or more parallel second tracks, and the carriage includes corresponding first restraint points defined on a first restraint axis and second restraint points defined on a second restraint axis.

[0021] In one embodiment the equipment is a work platform.

[0022] In one embodiment the stationary reference plane is a horizontal ground plane and the equipment reference plane is a work surface of the work platform that is maintained parallel to the ground plane during movement of the carriage.

[0023] In one embodiment the work platform is mounted on the carriage in a cantilevered arrangement.

[0024] In one embodiment the offset vector is selected so that the first and second restraint points are separated by a sufficient distance to support eccentric loading of the work platform.

[0025] In one embodiment the equipment includes at least one tool.

[0026] In one embodiment the at least one tool is a linerbolt removal tool.

[0027] In one embodiment the equipment reference plane is a tool reference plane that is maintained in a fixed orientation relative to the stationary reference plane during movement of the carriage, and the at least one tool is at least one of moveable and rotatable relative to the tool reference plane.

[0028] In one embodiment the apparatus includes an actuator for moving the carriage relative to the first and second tracks.

[0029] In one embodiment the actuator includes at least one of: a hydraulic actuator; a pneumatic actuator; and an electric actuator. [0030] It will be appreciated that the broad forms of the invention and their respective features can be used in conjunction, interchangeably and/or independently, and reference to separate broad forms is not intended to be limiting.

Brief Description of the Drawings

[0031] Various examples and embodiments of the present invention will now be described with reference to the accompanying drawings, in which: -

[0032] Figure 1A is a schematic diagram of an example of an elevating apparatus for moving equipment along a predetermined non-linear trajectory, in a lowered position;

[0033] Figure IB is a schematic diagram of the elevating apparatus of Figure 1 A, in an elevated position;

[0034] Figure 2 is a diagram of geometric parameters of an example of an elevating apparatus for moving equipment along an arcuate trajectory;

[0035] Figure 3 is a perspective view of an implementation of the elevating apparatus of Figure 1A;

[0036] Figure 4 is a perspective view of an implementation of another example of an elevating apparatus configured for moving a work platform about an exterior surface of a grinding mill;

[0037] Figures 5A to 5D are various perspective views of the elevating apparatus of Figure 4, in a lowered position, with the grinding mill hidden for clarity; and

[0038] Figures 6A to 6D are various perspective views of the elevating apparatus of Figure 4, in an elevated position, with the grinding mill hidden for clarity.

Detailed Description of the Preferred Embodiments

[0039] An example embodiment of an elevating apparatus 100 for moving equipment 110 along a predetermined non-linear trajectory 101 while an equipment reference plane is maintained in a constant orientation relative to a stationary reference plane 102 will now be described with reference to Figures 1A and IB. [0040] In broad terms, the apparatus 100 includes a moveable carriage 120 for supporting the equipment 110, and first and second tracks 130, 140 that are fixed relative to the stationary reference plane 102.

[0041] In this embodiment of the elevating apparatus 100, the equipment 110 supported by the carriage 120 is in the form of a work platform and the non-linear trajectory 101 is an arcuate trajectory. However, it should be appreciated that alternative embodiments of the elevating apparatus 100 may be used to move other types of equipment in other types of non-linear trajectories.

[0042] The carriage 120 includes a first restraint point 121 and a second restraint point 122 that is offset from the first restraint point 121 by an offset vector (in this particular example, the offset vector is defined by a horizontal offset of 50 mm and a vertical offset of 800 mm in the view plane of Figures A and B, as indicated). The first and second tracks 130, 140 define respective first and second paths 103, 104 each corresponding to the non-linear trajectory 101. The second path 104 is translated relative to the first path 103 by the offset vector. The carriage 120 is mounted to the first and second tracks 130, 140 so that the first restraint point 121 follows the first path 103 defined by the first track 130 and the second restraint point 122 follows the second path 104 defined by the second track 140 during movement of the carriage 120.

[0043] In use, as the carriage 120 is moved relative to the first and second tracks 130, 140, the equipment 110 supported by the carriage 120 moves along the non-linear trajectory 101, while an equipment reference plane 111 (in this particular embodiment being a work surface of the work platform) is maintained in a constant orientation relative to the stationary reference plane 102.

[0044] The apparatus 100 will typically be configured so that the carriage 120 and the supported equipment 110 can be elevated and lowered along the non-linear trajectory 101, with Figure 1A showing a lowered position and Figure IB showing an elevated position. Accordingly, it will be appreciated that embodiments of the elevating apparatus 100 may be used to provide an improved elevating work platform which is capable of being elevated and lowered along a desired non-linear trajectory 101, such as to move the work platform around the exterior surface of a grinding mill to facilitate access during linerbolt removal operations.

[0045] Such an arrangement can provide a range of advantages. An elevating work platform that moves around the profile of the exterior surface of the grinding mill reduces moving parts and improves safety compared to existing solutions for mill relining applications. The above described arrangement can effectively mitigate the issue of having a variable gap between the work platform and the exterior surface of the grinding mill.

[0046] The use of multiple tracks for guiding offset restraint points can also provide a more stable and strong structure for supporting the typically cantilevered work platform. This extra strength and stability is dependent on how the tracks and their respective paths are positioned relative to one another, i.e. the offset vector as discussed above, and this can be selected accordingly in the design of specific implementations to ensure eccentric loading of the work platform can be supported with sufficient safety margins.

[0047] More generally, it will be appreciated that the elevating apparatus 100 as described above can be used for supporting and moving equipment 110 within close proximity to and at a constant distance from a surface of a non-linear object, whilst maintaining the orientation of the equipment 110 relative to a stationary reference plane 102 during the entirety of its travel.

[0048] A range of optional features of preferred and/or alternative embodiments of the elevating apparatus will now be described.

[0049] Typically, the stationary reference plane 102 will be a horizontal ground plane, although this isn't necessarily the case. Assuming the horizontal ground plane is the stationary reference plane 102, in preferred embodiments the first and second tracks 130, 140 may be configured to define the first and second paths 103, 104 in respective parallel planes extending perpendicularly from the horizontal ground plane.

[0050] The non-linear trajectory 101 may be defined relative to a non-linear surface of an object. In some embodiments, the non-linear trajectory 101 may be defined to maintain a constant separation distance between a predetermined point on the equipment 110 and the non linear surface of the object. [0051] In some embodiments as discussed above, the object may be a grinding mill, such that the non-linear trajectory 101 is defined relative to an exterior surface of the grinding mill. It will be appreciated that grinding mills will typically have a cylindrical exterior surface, and accordingly, in some implementations, the non-linear trajectory 101 may be an arcuate trajectory corresponding to a curvature of the exterior surface of the grinding mill.

[0052] A simplified diagram illustrating geometric parameters of an example of an elevating apparatus for moving equipment along an arcuate trajectory 101 is shown in Figure 2. In this case, the first and second paths 103, 104 define respective first and second circular arcs having the same radius and respective first and second centre points 201, 202. The second centre point 202 is translated relative to the first centre point by the offset vector defined between the first and second restraint points 121, 122. In this particular example, the offset vector is defined by a vertical offset of 500 mm in the view plane of Figure 2, as indicated.

[0053] It will be appreciated that, as the first and second restraint points 121, 122 of the carriage 120 are moved along the respective circular arcs of the first and second paths 103, 104, the carriage 120 and supported equipment 110 will move along the corresponding arcuate trajectory 101.

[0054] Furthermore, since the first and second paths 103, 104 are translated by the offset vector that separates the first and second restraint points 121, 122, the orientation of an equipment reference plane 111 (such as a work surface of the work platform in Figures 1A and IB) can be maintained relative to the stationary reference plane 102.

[0055] The apparatus will typically include an actuator 150 for moving the carriage 120 relative to the first and second tracks 130, 140. The actuator 150 may be configured to cause the carriage 120 and supported equipment 110 to be selectively elevated or lowered, or otherwise maintained in a stable elevation relative to the horizontal ground plane.

[0056] In preferred implementations, the apparatus 100 may include a frame 160 that is fixed relative to the stationary reference plane 102. The first and second tracks 130, 140 may in turn be supported by the frame 160. The frame may include a base portion that is mounted on a generally horizontal surface for supporting the frame relative to the surface, and an upright portion that extends upwardly from the surface. [0057] Further construction features of an example implementation of the elevating apparatus 100 can be seen in Figure 3. In this example, the first and second tracks 130, 140 may form integral structural parts of the upright portion of the frame 160. However, in other examples the tracks 130, 140 may be attached to other structural members of the frame 160.

[0058] The carriage 120 may be provided as a fitting or the like that straddles the tracks 130, 140 to thereby locate its restraint points relative to the respective tracks 130, 140. The carriage 120 will typically be mechanically coupled to the equipment 110 (i.e. the work platform in this example) such that the weight and other loading applied to the equipment 110 can be supported by the tracks 130, 140 and reacted by the surface upon which the frame 160 is mounted.

[0059] In preferred embodiments, the carriage 120 includes respective rollers at each of the first and second restraint points 121, 122, with each roller being guided by a respective one of the tracks 130, 140. The tracks 130, 140 may in turn be provided in the form of curved channels configured to receive the respective rollers and guide the rollers along the respective first and second paths 103, 104 as described above.

[0060] In the example implementation as shown in Figure 3, the apparatus 100 includes two parallel first tracks 130 and two second tracks 140. The carriage 120 may include corresponding first restraint points defined on a first restraint axis and second restraint points defined on a second restraint axis. It will be appreciated that the use of parallel pairs of first and second tracks 130, 140 can provide a more stable and stronger arrangement whilst facilitating the capability for movement along a non-linear trajectory as described above. In this example, the pairs of tracks 130, 140 are interconnected to provide an even more stable structure.

[0061] As already discussed above, in some embodiments the equipment 110 is provided in the form of a work platform. Typically, the stationary reference plane 102 will be a horizontal ground plane and the equipment reference plane 111 may be a work surface of the work platform that is maintained parallel to the ground plane during movement of the carriage 120. In view of the description above, it will be appreciated that the stable orientation of the work surface will be inherently maintained as a result of the geometrical arrangement of the restraint points 121, 122 and the paths 103, 104 defined by the tracks 130, 140, without requiring any complex moving parts for controlling the orientation of the work surface.

[0062] In the depicted embodiments, the work platform is mounted on the carriage 120 in a cantilevered arrangement. In such a cantilevered arrangement, the offset vector may be selected so that the first and second restraint points 121, 122 are separated by a sufficient distance to support eccentric loading of the work platform.

[0063] Additionally or alternatively, the equipment 110 supported by the carriage 120 may include at least one tool, and in some examples, the at least one tool may be a linerbolt removal tool for use in linerbolt removal operations. In these cases, the equipment reference plane 111 may be a tool reference plane associated with the tool, which is maintained in a fixed orientation relative to the stationary reference plane 102 during movement of the carriage 120. The at least one tool may be moveable and/or rotatable relative to the tool reference plane.

[0064] Any suitable form of actuator 150 may be used, such as a hydraulic actuator, a pneumatic actuator or an electric actuator. In the examples of Figures 1A and IB and Figure 3, the actuator 150 is coupled between a base portion of the frame 160 and an actuator coupling point on the carriage 120. When the actuator 150 is extended, the carriage 120 and supported equipment 110 will be elevated, and when the actuator 150 is retracted, the carriage 120 and supported equipment 110 will be lowered, following the predetermined non-linear trajectory during movement in either direction. Although the depicted examples use a linear actuator, it should be appreciated that a range of alternative actuator arrangements may be used, such as winch and pulley arrangements or rack and pinion arrangements.

[0065] Turning back to Figures 1A and IB, it is noted that the work platform may additionally include a guard rail extending above the work surface 111, with the guard rail including a fixed guard rail portion 112 and a moveable guard rail portion 113 at a distal end of the work surface 111 opposing the carriage 120. The moveable guard rail portion 113 is configured to be moved by a guard rail actuator 114 to vary the distal extent of the guard rail.

[0066] For example, when the carriage 120 and supported work platform is lowered as shown in Figure 1A, the moveable guard rail portion 113 is retracted, whilst when the carriage 120 and supported work platform are elevated as shown in Figure IB, the moveable guard rail portion 113 is extended. It will be appreciated that, in embodiments where the trajectory is defined to closely follow a surface of an object, such as an exterior surface of a grinding mill, this functionality can be used to ensure the guard rail extends into close proximity with the object but without interference with the object, throughout the range of motion.

[0067] A further example of an embodiment of an elevating apparatus 400 specifically configured for moving a work platform 410 about an exterior surface of a grinding mill 401 is shown in Figure 4. In this case, the non-linear trajectory is selected so that the work platform 410 supported by the carriage 420 is elevated while maintaining a constant separation from the curved exterior surface of the grinding mill 401. The configuration and operation of the work platform 410, carriage 420, tracks 430, 440, actuator 450 and frame 460 are generally in accordance with corresponding elements in the description of other examples as set out above.

[0068] However, in this example, the carriage 420 also supports an overhead structure 470 above the work platform 410. This overhead structure 470 will be elevated and lowered together with the work platform 410 and may be used to suspend tools such as linerbolt removal tools or the like, as shown in Figures 5A-5D and Figures 6A-6D. It will be appreciated that this can allow personnel to manipulate the tools without having to bear the significant weight of such tools. Power units 480 for the tools, or the like, may be installed separately from the moving work platform 410 and overhead structure 470 as shown, so that these do not have to be supported by the carriage 420 and tracks 430, 440.

[0069] Figures 5A-5D and Figures 6A-6D show the elevating apparatus 400 in use (with the grinding mill hidden for clarity), with personnel on the work platform 410 and operating tools suspended from the overhead structure 470. In particular, Figures 5A-5D show various views of the work platform 410 and overhead structure 470 in a lowered position and Figures 6A-6D show various views of the work platform 410 and overhead structure 470 in an elevated position.

[0070] In view of the above described examples, it will be appreciated that embodiments of the elevating apparatus may provide a method of maintaining and moving suspended equipment within close proximity and at a constant distance from a non-linear object whilst maintaining the relative angle of the equipment to a stationary reference plane during the entirety of its travel.

[0071] The elevating apparatus provides two separate paths/tracks to control the motion of the suspended equipment. The two paths/tracks control the direction of movement of two points of restraint on the suspended equipment. Each point of restraint locates in one of the two paths/tracks. Movement of the suspended apparatus causes the two restraint points to move along their separate paths/tracks to achieve the desired and aforementioned case of motion and angular alignment.

[0072] The elevating apparatus can be advantageously applied, for example, in cases where it may be desirable to elevate a work platform in a circular arc of motion. In this instance, the two paths/tracks provided for the control of the motion take the form of two circular arcs with their centre points offset by the same vertical and horizontal distances as the two restraint points supplied on the suspended work platform. The restraint points of the work platform may take the form of rollers and may be positioned at a sufficient distance from one another to support the offset load of the work platform. The tracks containing the rollers and controlling their motion may take the form of two curved channels that maintain the rollers within the two sides of the channel. Raising and lowering the platform by any means causes the rollers to travel within the curved arc of the two channels and produces a circular arc motion of the work platform without affecting the angle of the platform to the ground.

[0073] In some implementations, the paths/tracks used to control the motion of the restraints may be a combination of at least two paths/tracks. The suspended equipment will typically be mechanically linked to the restraint points located in the paths/tracks but may be positioned anywhere in relation to the paths/tracks.

[0074] Although the previous examples have shown suspended equipment in the form of a work platform, it should be appreciated that a range of alternative types of equipment could additionally or alternatively be provided to move in the path of controlled motion in a similar manner as described above. Instead of providing an elevating work platform for allowing personnel to access an exterior surface of a grinding mill, the elevating apparatus could be used to move automated robotic machinery around the grinding mill surface. [0075] It should be appreciated that the trajectory of the motion is not limited to arcuate trajectories corresponding to the cylindrical exterior surface of a ball mill. The elevating apparatus has the potential for moving level platforms or other supported equipment through any non-linear path, such as parabolic or recurve paths.

[0076] Throughout this specification and claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers. As used herein and unless otherwise stated, the term "approximately" means ±20%.

[0077] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a support” includes a plurality of supports. In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.

[0078] It will of course be realised that whilst the above has been given by way of an illustrative example of this invention, all such and other modifications and variations hereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of this invention as is herein set forth.