AU2020203661B2

AU2020203661B2 - Improvements to large scale machining apparatus

Info

Publication number: AU2020203661B2
Application number: AU2020203661A
Authority: AU
Inventors: Mitchell Purcell; Terence Purcell
Original assignee: Mbher Pty Ltd
Current assignee: Mbher Pty Ltd
Priority date: 2016-11-03
Filing date: 2020-06-03
Publication date: 2021-07-15
Anticipated expiration: 2037-10-06
Also published as: AU2020100927A4; AU2017239610A1; AU2020203661A1

Abstract

An apparatus for machining a workpiece such as dragline components, large tanks, gear cases, pressure vessels, slew ring mounting faces and odd shape pieces such as turbine cases and pump cases or castings, the apparatus including a plurality of booms rotatable about a common pivot point, each boom having an associated machining station. 1/8 ILL

Description

1/8

ILL

AUSTRALIA PATENTSACT1990

COMPLETE SPECIFICATION IMPROVEMENTS TO LARGE SCALE MACHINING APPARATUS

The following statement is a description of the invention:

IMPROVEMENTS TO LARGE SCALE MACHINING APPARATUS

TECHNICAL FIELD The present invention concerns machining apparatus for machining of large scale apparatus including, but not limited to, dragline components, large tanks, gear cases, pressure vessels, slew ring mounting faces and odd shape pieces such as turbine cases and pump cases or castings.

BACKGROUND ART Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

Figures 1A to 1C are respectively plan, isometric and side elevation views of a pivoting machining apparatus 1 shown installed for working on a workpiece, in the form of a dragline tub 3. The pivoting machining apparatus 1 includes a boom 5 that extends radially away from a collar 7 which locates about a central pivot 9. The boom 5 is fitted with powered ground contact wheel assemblies 11 that when operated cause the boom to rotate in a horizontal plane around the central pivot, for example in a clockwise or anti-clockwise direction as indicated by arrows 15a and 15b. Typically a manual machining tool is fitted to a carriage at the end of the boom. As the boom 5 rotates the carriage and hence the machining tool may slide radially in and out and also vertically up and down to perform operations on the surface and/or outer rim and lip of the tub 3 at desired locations. As is known in the prior art the tool may be a grinder/milling cutter or single point tool for performing levelling operations. Apart from the grinding operation it may also be necessary to drill and ream any number of holes in the surface. One prior art approach to drilling such holes is by the use of manual radial arm drills. These are manual, heavy and difficult to maneuver over the surface of the workpiece.

A problem that arises with the use of a machining apparatus, such as the machining apparatus 1 that is shown in Figures 1A to 1C is that it is often the case that the articles that are being machined, for example the dragline tub 3, have a large downtime cost associated with them. Consequently, it is very important that the machining process is completed as quickly as possible. However, because of the accuracy that is required in the machining process, the boom 5 must be rotated relatively slowly and so the machining process takes a considerable time to complete.

One way of reducing the time taken would be to speed up the motion of the boom and the associated machining operations of the machine tools. However, increasing the speed may result in inaccuracies and instabilities occurring which reduces the quality of the finished job and so is undesirable.

There is a need for an improved machining apparatus for large scale workpieces.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for machining a workpiece, the apparatus including: a plurality of booms rotatable about a common pivot point, each boom having an associated machining station, wherein the booms are each coupled to wheels for pivoting the booms about the pivot point.

In a preferred embodiment of the invention the booms are disposed equi angularly to each other.

In an embodiment the apparatus includes a central collar that is centered over the pivot point and from which each of the booms radiates, the central collar having a number of sides corresponding to the number of booms.

In the preferred embodiment of the invention the plurality of booms comprises three booms though two or four or more booms may be present in other embodiments of the invention.

It is preferred that at least one of the wheels is powered for pivoting the booms about the pivot point. Where three booms are used they are preferably disposed at 120 degrees to each other.

In one embodiment of the invention the apparatus includes a central triangular brace that is centered over the pivot point and from which each of the three booms radiates.

The associated machining station of each of the plurality of booms may be operable independently of the others. Alternatively, in some embodiments the operation of the machining stations may be combined so that they operate in concert. In a preferred embodiment of the invention each of the machining stations includes a computerized control assembly for controlling a tool of the machining station.

It is preferred that each of the machining stations is arranged for receiving an interchangeable tool including one of at least a milling tool, for machining the workpiece and a drilling tool for drilling into the workpiece.

In a preferred embodiment of the invention each of the workstations is arranged to move the tool up and down and radially in and out.

Preferably the computerized control assemblies are arranged to interact with respective operator wireless devices for input of operator controls. In other embodiments of the invention the operator control may be manual or wired.

According to another aspect of the present invention there is provided a method for machining a workpiece including: providing a plurality of booms, each extending from a common central pivot and each supporting an associated machining station supporting a tool; moving each of the plurality of booms with the same angular velocity about the common central pivot; and operating the tool of each said machining station for machining the workpiece.

In an embodiment each machining station includes a carriage arranged to slide radially along a portion of a respective one of the plurality of booms, the method including effecting radial sliding of each carriage by operating linear actuators arranged to slide the carriages along the portions of the booms.

The linear operators may be controlled by respective computerized control assemblies of the machining station, the method including operating each of the machining stations with respective human-machine-interfaces.

The method may include interchanging the tool supported by each milling station for another tool wherein the tools that are interchanged include at least a milling tool, for milling the workpiece and a drilling tool for drilling into the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

Figures 1A, 1B and 1C are top plan, isometric and side views of a prior art machining apparatus shown in use. Figure 1D is a top plan view of a machining apparatus according to a preferred embodiment of the present invention. Figure 2 is an end view of a boom of the apparatus of Figure 1D, shown with a milling tool installed. Figure 3 is an end view of the boom of the apparatus of Figure 2, shown with a drilling tool installed. Figure 4 is a top plan view of the machining apparatus of Figure 1D in use.

Figures 5, 6 and 7 are top plan, isometric and side views of a machining apparatus according to a further embodiment of the present invention, shown in use.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring initially to figure 1D there is shown a plan view of a rotary machining apparatus 2 installed for machining a workpiece 4. In the present example the workpiece comprises a cylindrical drag line tub. The rotary machining apparatus includes a plurality of booms, namely three booms 6a, 6b, 6c. The booms extend radially from respective sides of a central, isometric, triangular brace 8 which has a central collar 10 that locates about, and which is rotatable around, a pivot 12. Accordingly, the three booms 6a, 6b, 6c which are angularly separated by 120 degrees are able to pivot about the common central pivot 12. It is preferred that the booms are each coupled to respective wheel assemblies 13a, 13b, 13c wherein at least some of the wheels are powered for pivoting the booms about the pivot 12. In the presently described preferred embodiment of the invention there are three booms 6a, 6b, 6c. It will be realised that two, or four or more, booms may be present in other embodiments of the invention. For example, where four booms are present the triangular brace 8 will be replaced with a four sided, e.g. square, brace from which each of the four booms extends.

Referring again to Figure 1D, towards their respective outer ends, each of the booms 6a, 6b, 6c terminate with radially extending opposed rail portions 18a, 18b and 18c. Each of the booms 6a, 6b and 6c support an associated machining station 14a, 14b, 14c. Each machining station 14a, 14b, 14c includes a carriage 20a, 20b and 20c, which is arranged to slide radially outwardly and inwardly along the respective rail portions 18a, 18b, 18c of the its respective boom 6a, 6b, 6c. The radial motion of the carriages 20a, 20b, and 20c may be effected by linear actuators which slide the carriages along the rails. The operation of the linear actuators and of machine tools that are interchangeably fitted to the carriages are controlled by respective computerized control assemblies 22a, 22b and 22c of the machining stations 14a, 14b, 14c. In other embodiments of the invention the machine tools and the linear actuators may be controlled manually or by a CNC or NC assembly.

Referring now to Figure 2, there is shown an end view along the line "A" indicated in Figure 1, of the outer end of boom 6a. In the view shown in Figure 2 the carriage 20a supports an interchangeable tool in the form of a rotary grinder 26a that is powered by an electric motor 24a under control of control assembly 22a. The control assembly 22a is arranged to respond to a laser levelling signal that allows it to raise and lower the grinder 26a to ensure that the surface of the workpiece 4 is machined perfectly flat. Arrangements for raising and lowering the machining tool and for the use of laser levelling control systems are known in the prior art and do not form part of the present invention.

The controller 22a communicates wirelessly with a human-machine-interface in the form of a portable electronic device 28a that presents a user interface to operator 30a. Consequently the operator is able to interact with the controller 22a and thus the functioning of the grinder tool 26a. In other versions the controller may be manual or may be wired to the human-machine-interface.

Referring now to Figure 3, there is shown an end view along the line "A" indicated in Figure 1D, looking towards the outer end of boom 6a, similar to the view of Figure 2 but with the milling tool 26a of Figure 2 replaced by a controlled drill 27. Once again, in the presently described embodiment of the invention the controller 22a communicates wirelessly with the human-machine-interface in the form of portable electronic device 28a that presents a user interface to operator 30a. Consequently the operator is able to interact with the controller 22a and thus modify or stop the functioning of the drill 27 as necessary.

Referring now to Figure 4, in use the powered wheel assemblies 13a, 13b, 13c are activated so that the tri-form boom assembly formed by booms 6a, 6b, 6c and triangular brace 8, pivots in a horizontal plane about pivot 12 as indicated by arrows 29a, 29b, 29c, over the surface of the workpiece 4. Operators 30a, 30b, and 30c make use of portable devices 28a, 28b and 28c to interact with respective control assemblies 20a, 20b and 20c. For example, in the event of an emergency the operators may need to command the control assemblies to cease operation of the drilling and machining tools.

It will be realised that since there are three booms which all move with the same angular velocity about the pivot 12, the time taken for one boom to move over an underlying region of the workpiece 4 is one third of the time that would be taken if there were just a single boom as was the case with prior art machining apparatus of Figures 1A to 1C. In effect, due to the ability to simultaneously work the machining stations 14a, 14b, 14c the time for machining the workpiece is reduced relative to the time that would be taken by the prior art machine of Figures 1A to 1C. Furthermore, since the booms may be fitted with drills there is no need to have to manoeuvre heavy manual drills over the surface of the workpiece.

It will be realised from the previous discussion that an embodiment of the invention comprises a machining apparatus with a plurality of booms that can each accommodate two or more interchangeable heads so that the apparatus can mill as well as drill under either automatic (e.g. CNC or NC) control or manually. This allows holes to be drilled on predetermined paths or at random points saving time in set up of drilling machines when machining is complete. It also allows for much faster metal removal by having more milling heads on the apparatus. Also if only one mill head is required (for example on machining station 20a) then the other machining stations (e.g. stations 20b and 20c) can be fitted with light weight drills. The apparatus 2 can then be driven, by means of wheel assemblies 13a to 13c to a particular region and all the holes in that region can be drilled by more than one drill if pre-marked, or by use of an encoder, a single point drill can drill along a predetermined set line or random pattern. These drill and mill heads can also be set at different angles if required, to allow machining upside down or at an infinite number of angles.

Figures 5 to 7 are views of a further machining apparatus 31 according to another embodiment of the present invention. The machining apparatus 31 includes outer boom extensions 33a, 33b, 33c which extend beyond the edge of the workpiece and which include tool platforms 35a, 35b, 35c for fitting tools for machining the outer edge and peripheral lip of the workpiece, e.g. the dragline tub shown in the Figure. Outer boom extensions and tools for machining the outer edge and peripheral lip are known in the prior art and so will not be described in detail here since they do not form part of the present invention.

A preferred embodiment of the invention is able to operate on a workpiece having a minimum diameter - 4000mm; maximum Diameter - greater than 4000mm depending on the length of the available booms; minimum Height 1400mm; maximum Height - 2000mm. Of course these are only exemplary dimensions and other versions of the machining apparatus according to the present invention may be provided to deal with workpieces of other dimensions.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, such as "comprising" and "comprised of' is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described herein comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims

The claims defining the invention are as follows:

1. An apparatus for machining a workpiece, the apparatus including: a plurality of booms rotatable about a common pivot point, each boom having an associated machining station, wherein the booms are each coupled to wheels for pivoting the booms about the pivot point.

2. An apparatus according to claim 1, wherein the booms are disposed equi angularly to each other.

3. An apparatus according to claim 2, including a central collar that is centered over the pivot point and from which each of the booms radiates, the central collar having a number of sides corresponding to the number of booms.

4. An apparatus according to claim 1 or claim 2, wherein the plurality of booms comprises three booms.

5. An apparatus according to claim 4 including a central triangular collar that is centered over the pivot point and from which each of the three booms radiates.

6. An apparatus according to any one of the preceding claims, wherein at least one of the wheels is powered for pivoting the booms about the pivot point.

7. An apparatus according to any one of the preceding claims wherein the associated machining station of each of the plurality of booms is operable independently of the others.

8. An apparatus according to any one of the preceding claims, wherein each of the machining stations includes an assembly for controlling a tool of the machining station.

9. An apparatus according to any one of the preceding claims wherein, each of the machining stations is arranged for receiving an interchangeable tool including one of at least a milling tool, for milling the workpiece and a drilling tool for drilling into the workpiece.

10. An apparatus according to claim 9, wherein each of the workstations is arranged to move the tool up and down and radially in and out.

11. An apparatus according to any one of claims 8 to 10, wherein the control assemblies are arranged to interact with respective remote operator devices for input of operator controls.

12. A method for machining a workpiece including: providing a plurality of booms, each extending from a common central pivot and each supporting an associated machining station supporting a tool; moving each of the plurality of booms with the same angular velocity about the common central pivot; and operating the tool of each said machining station for machining the workpiece.

13. A method according to claim 12 wherein each machining station includes a carriage arranged to slide radially along a portion of a respective one of the plurality of booms, the method including effecting radial sliding of each carriage by operating linear actuators arranged to slide the carriages along the portions of the booms.

14. A method according to claim 13 wherein the linear operators are controlled by respective computerized control assemblies of the machining station, the method including operating each of the machining stations with respective human-machine-interfaces.

15. A method according to any one of claims 12 to 14 including interchanging the tool supported by each milling station for another tool wherein the tools that are interchanged include at least a milling tool, for milling the workpiece and a drilling tool for drilling into the workpiece. * * *