WO2002033219A1

WO2002033219A1 - Cutter

Info

Publication number: WO2002033219A1
Application number: PCT/AU2001/001347
Authority: WO
Inventors: Matt Panozzo; David O'sullivan
Original assignee: MINE SITE TECHNOLOGIES Pty Ltd; Mine Site Technologies Pty Ltd
Current assignee: MINE SITE TECHNOLOGIES Pty Ltd; Mine Site Technologies Pty Ltd
Priority date: 2000-10-20
Filing date: 2001-10-22
Publication date: 2002-04-25
Anticipated expiration: 2003-04-20
Also published as: AUPR090900A0

Abstract

A cutter for insertion on a cutter head comprising: (a) a bearing assembly (1) comprising: (i) an external integral annular cone (4); (ii) a pair of opposed internal annular cups (2) located in and bearing upon the cone (4) whilst being coaxial therewith; and (iii) an annular spacer (3) located between the opposed cups (2) to maintain those cups in a predetermined location relative to the cone (4); (b) an annular hub (6) having a central recess into which the bearing assembly (1) is releasably inserted; (c) a central shaft (6) releasably and axially located within the bearing assembly (1); and (d) a cutter ring (9) releasably located on the external circumference of the hub (6).

Description

CUTTER

Field of the invention

The invention relates to an improvement in a cutter. More particularly the invention relates to a cutter used as part of a cutter head for tunnel boring machinery (7-SΛ ).

Background of the invention

In this specification, where a document, act or Item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date: (i) part of common general knowledge; or

(ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.

Whilst the following discussion concerns a cutter used in association with cutter heads found on TBM it is to be understood that the invention may be applicable to other machinery utilising a cutter(s) as part of a cutting head or a similar cutting structure such as shaft drilling machinery (raise boring/down drilling machinery) and microtunnelling machinery.

Tunnel boring machinery is used in civil tunneling and mining. A TBM includes a rotary cutter head which is positioned at the front part of the TBM main frame and connected to the rest of the TBM, usually by numerous thrust cylinders. In operation, the cutter head is rotated and the thrust cylinders activated to extend the cutter head forward to tunnel into the ground ahead.

Raise boring/down drilling machinery is used in civil tunnelling and mining to create vertical or near vertical shafts. The drilling machinery has a rotary cutter head that is either raised up or forced down by thrust rams to create a vertical or near vertical circular shaft. In operation, the cutter head is rotated and the thrust cylinders are activated to either retract or extend the cutter head forward into the shaft, typically it is guided by a pilot hole.

Microtunnelling uses the same theory as TBM but on a smaller scale.

Each cutter head has a plurality of cutters. These cutters are usually circular and are inserted into the cutter head by wedging or fixing the cutter in a complementary housing usually in the form of apertures. The cutters are, in turn, composed of a number of individual interlocking parts.

The cutter generally comprises a central shaft, a bearing component made up of a pair of annular bearings spaced apart by a spacer, an external hub, a cutter ring and a pair of end caps.

Bearings are traditionally designed to support and locate rotating shafts or parts in machines. Bearings transfer loads between rotating and stationary members and permit relatively free rotation with a minimum of friction. Bearings consist of rollers placed between an outer and inner ring. The outer ring is commonly referred to as the cone, while the inner ring is commonly referred to as the cup. Cages or racers are used to space the rollers from each other.

The bearings are located within the hub. This structure is in turn inserted onto the central shaft and secured by a pair of end caps, each cap placed on an alternate side of the hub. The cutter ring is then inserted over the hub. The individual components can be further secured by retainers and seals.

In operation, each cutter can move in a circular motion around the central shaft by the operation of the bearings. The bearing cups (inner portion) engage the central shaft while the cones (outer portion) engage the hub (directly) and cutter ring (indirectly). Thus, the bearings allow for the independent movement of the cutter ring relative to the central shaft.

The cutters wear as the TBM or raise borer/down drilling machine progressively excavates into the ground ahead. The cutters are replaced at specific intervals which depend upon the hardness of the ground being excavated, and the quality and strength of material used in manufacturing the cutter. Certain components of the cutter require replacement as they wear, however, given that different components are constructed of different material and are under different stresses during operation, not all components wear at the same rate. Typically, the external cutter ring wears first since it engages the ground during excavation.

Depending on the prevailing ground being excavated, a TBM operator will remove all disc cutters located on the cutter head of the TBM and replace them with a new or refurbished set. Some cutter heads are composed of up to 90 separate cutters resulting in a long replacement process and an increase in operating costs.

The removed cutters are then taken away and inspected where an assessment is made as to whether they should be replaced, or refurbished. Typically, when the external cutter ring is replaced the remaining components such as the hub, bearings, spacer and seals are inspected during the changeover. If the operator determines that the hub has worn to an unacceptable level, then the whole unit is dismantled and each separate part inspected. If the hub is not overly worn, the entire unit is checked to ensure that it rotates to a given torque and has no 'play' (ie undesirable movement). This gives some indication whether it is necessary to inspect the internal components of the cutter. If the operator considers inspection necessary, the whole unit is disassembled and each separate component inspected.

Once the unit is disassembled, the relevant components can be replaced or kept and the unit can be reassembled. The assembly procedure is often complex and time consuming, especially if 90 separate cutters have to be inspected, and possibly replaced.

Disassembly involves an initial inspection of the cutter. The cutter is usually given a light clean before inspection to remove loose dirt from the cutter's exterior surface. The cutter ring can then be removed typically by the application of heat. To avoid burning the hands of an operator and heat damage to the hub, water is applied immediately after heating to allow an operator to pull the ring free from the hub.

The disassembly procedure then takes place from one side. An end cap is removed and the seals are inspected. The seal face must be free of any scratches, nicks or burs. If the seal shows these characteristics, it is discarded. If not, the seal can be re-used.

The central shaft can then be removed to allow for the removal of the top cone component of one bearing and then the hub assembly. The detached cone is then inspected to detect deformation of the roller cage, flat spots, indentations, flaking and brinelling, or cracking of the rollers. The presence of these types of defects or damage will cause the bearing to be discarded.

The cup component of the bearing is then inspected for signs of wear as evidenced by indentations, flaking, brinelling or cracks. If any wear is observed the entire bearing will be replaced. The spacer is discarded. Finally, the hub and shaft component can then be inspected.

Each of the individual parts is then cleaned with oil free solvents. The parts can be deburred and then once again inspected and lubricated as required.

The cutter can then be reassembled by using a hydraulic press. Initially the bearing cups (either the existing cups or new cups) are installed, one at a time from each side onto the hub. The operator is then required to determine the relevant bearing cone gap and select an appropriate master spacer.

The cutter unit can then be reassembled without seals by initially installing the end cap onto the shaft, and then placing a bearing cone onto the shaft. The hub (and bearing cups) can be placed onto the shaft, a master spacer is then placed in position. The remaining bearing cone is inserted onto the shaft using the hydraulic press, followed by the remaining end cap.

The exact thickness of the spacer must be determined by calibrating the movement of the hub element. This is done by considering and using formulas and measurements which allow the dimensions of the spacer to be calibrated.

A spacer is machined to the requisite thickness thereby ensuring that the correct pre-load is placed on the bearing assembly.

The cutter is then disassembled to allow the machined spacer to be inserted. The cutter is then reassembled as above, however seals and lubricants are now added. This method, although effective, is nonetheless time consuming, requiring two disassembly steps, access to both sides of the cutter unit, and specialised equipment such as a hydraulic press and various calibrating tools. This time, of course, must be multiplied by up to 90 times dependent on how many cutters are located within the TBM cutter head. The other disadvantage of the conventional cutter assembly lies in the fact that an operator must undertake several cleaning and calibrating steps which are not only time consuming, but require specialized equipment and are open to human error.

Furthermore, the internal components of the cutter, in particular, the bearings can be contaminated by the environment during the reassembly process which may affect the operation and longevity of the cutter. Summary of the invention

In accordance with one form of the invention, a cutter is provided, the cutter comprising:

(a) a bearing assembly comprising: (i) an external integral annular cone;

(ii) at least one pair of opposed internal annular cups located in and bearing upon the cone whilst being coaxial therewith; and

(iii) an annular spacer located between the opposed cups to maintain those cups in a predetermined location relative to the cone; (b) an annular hub having a central recess into which the bearing assembly is releasably inserted;

(c) a central shaft releasably and axially located within the bearing assembly; and

(d) a cutter ring releasably located on the external circumference of the hub.

Preferably, the spacer is of a pre-calibrated thickness suitable to maintain the appropriate spacing between the pair of internal cups.

The external cone can also act as a shield to protect the internal bearing mechanisms from contamination and damage during assembly and use. Suitable bearing mechanisms located between the cone and the cups may comprise roller means such as taper rollers, rollers, or balls. Preferably cages or separators are used to space the roller means from each other.

With a cutter according to the invention, it is possible for the entire bearing assembly to be interchangeably mounted in a cutter.

Preferably, the hub can incorporate an external circumferential groove in which the cutter ring can be located. Preferably, the cutter further comprises a retainer specifically adapted to lock various components into position.

In one embodiment, the retainer comprises a pair of annular end caps eatable on the central shaft in registry with the hub and bearing assembly on opposite sides of the hub. The annular end caps prevent the hub from moving relative to one end of the central shaft. Other retainers can include a cutter retaining ring to maintain the interlocking fit between the cutter ring and the hub by wedging the ring in registry with the hub.

Further retainers can include a bearing retaining ring which is preferably locatable between an end cap, one side of the hub and bearing assembly. Preferably the bearing retaining ring can include an elongated lip portion, a plurality of recesses and a threaded external portion.

In a further preferred embodiment, an end of the hub has a ledge or step which decreases the internal diameter of the recess of the hub. The ledge can engage a portion of the bearing assembly to prohibit the bearing assembly from passing through the hub. The opposite end of the hub has an internal threaded portion. The bearing assembly can be secured within the hub by the bearing retaining ring. When the bearing assembly is inserted into the hub, a portion of the bearing assembly is initially engaged by the ledge. The bearing retaining ring is then inserted by screwing the bearing retaining ring's external threaded portion in engagement with hub's complementary internal threaded portion. The raised lip portion engages an internal surface of the hub. A drill can then be used to drill through the plurality of recesses and into corresponding points on the internal planar surface of the hub. Taps are inserted through the recesses and drilled holes to secure the bearing retaining ring to a planar surface of the hub thus securing the bearing assembly within the hub. Alternatively the bearing ring can be secured to the hub by suitable adhesive such as Locktite™.

Seals can also be incorporated within the cutter. The seals act to protect the components of the cutter from contamination from the outside environment. The seals can also urge a better fit between the components.

In this preferred embodiment, a method of assembling a cutter according to the invention is provided comprising the steps of:

(a) locating the bearing assembly into the hub;

(b) passing the central shaft through the bearing assembly;

(c) locating the pair of opposed end caps on the shaft on either side of the assembly to engage the hub; and (d) locating the cutter ring on the external circumferential surface of the hub. The assembled cutter can then be located on a cutting surface. The assembly method can further comprise the steps of

(e) inserting retaining means; and/or

(f) inserting seals into the cutter assembly.

These additional steps can be performed before or after steps (b) to (d). For example, the addition of a bearing retaining ring occurs before step (b) and after step (c) while the addition of a cutter retaining ring occurs after step (d).

The bearing assembly can be placed onto the hub by a hydraulic press. Similarly, the hydraulic press can also be used to place the hub and bearing assembly on the shaft.

The bearing retaining ring can be placed within the hub by a retaining tool. The retaining tool typically comprises a circular engaging element with a plurality of projections and a cross-sectional handle. The plurality of projections are locatable within complementary recesses located on the bearing retaining ring. The handle can then be rotated to facilitate the threaded engagement between the bearing retaining ring and the annular hub.

In a further preferred embodiment, a method of assembling a cutter is provided comprising the steps:

(a) locating the bearing assembly into the hub; (b) passing the central shaft through the bearing assembly;

(c) locating the pair of opposed end caps on the shaft on either side of the assembly to engage the hub;

(d) drilling holes through the plurality of recesses and into corresponding points on the internal planar surface of the hub; (e) inserting a retaining tool wherein a plurality of projections are located within complementary recesses located on the bearing retaining ring,

(f) rotating the retaining tool relative to the bearing retaining ring and annular hub to facilitate a threaded engagement between the bearing retaining ring and the annular hub; and (g) locating the cutter ring on the external circumferential surface of the hub by wedging the ring in registry with the hub.

Investigations indicate that the present invention and associated method of assembly exhibit some advantages over cutters incorporating known bearing assemblies. For example, the pressing of the bearing assembly either into the hub or over the shaft is effectively done once, rather than twice and from one side only. The entire bearing assembly may be inserted onto the central shaft from one side as opposed from two sides.

Furthermore, no initial disassembly of the cutter during the assembly procedure is generally required. There are thought to be less components to inspect and assemble during maintenance of the cutter.

This in turn may reduce the man-hours required during normal inspection, disassembly and assembly procedures associated with the maintenance of the cutters. Any reduction in man hours is increased dependant on the number of cutters located on the cutter unit. The obvious commercial advantages to operators may be significant.

Description of the drawings

The invention will now be further explained and illustrated by reference to the accompanying drawings in which:

Figure 1 is cross sectional view of the bearing assembly; Figure 2 is a front view cross sectional of the bearing assembly of Figure 1;

Figure 3 is a cut away view of the cutter according to the invention ; and

Figure 4 is an assembly view of the cutter of Figure 3.

As is shown in Figure 2, the bearing assembly 1 is annular in shape. As shown in Figure 1 the bearing assembly 1 is comprised of two internal annular cups 2, spaced apart by an annular spacer 3. The bearing assembly is encased in an external annular integral cone 4. Rolling elements 5 are placed between the space defined by the cone 4 and the cups 2. Normally, the rolling elements are ball or roller bearings. However, other rolling elements such as taper rolls can be used. Cages (not shown) are used to space the rolling elements 5 from each other. The cone 4 can rotate independently of the cups 2. In use, the bearing assembly is inserted as a self contained unit within the cutter.

The spacer 3 is of a pre-calibrated thickness required to maintain the requisite spacing between the pair of internal cups 2. The external cone 4 acts as a shield to protect the internal bearing mechanisms including the rolling elements 5 and cage from contamination and damage during cutter assembly use.

Figures 3 and 4 depict a bearing assembly as incorporated within the cutter. The cutter comprises further elements including an annular hub 6, a pair of end caps 7, a central shaft 8, a cutter ring 9, bearing retaining rings 10, a cutter retaining ring 11, and seals 12.

As can be seen from Figure 4, the hub 6 incorporates an external circumferential groove 6a in which the cutter ring 9 can be located. The cutter retaining ring 11 maintains the interlocking fit between the cutter ring 9 and the hub 6 by insertion into the circumferential groove 6a thereby wedging the cutter ring 9 into registry with the hub 6. The hub 6 further has an internal ledge or step (not shown) which decreases the internal diameter of the hub 6 and an internal threaded portion 6b located at the opposite to the hub 6. The ledge can engage a portion of the bearing assembly 1 when the bearing assembly is inserted in the hub. The bearing assembly 1 is effectively stopped from passing through the hub 6. The bearing retaining ring 10 has an elongated lip portion 10a, an extended threaded portion 10b and a plurality of recesses 10c.

The bearing assembly can be secured within the hub by bearing retaining ring 10.

After the bearing assembly 1 is placed within the hub 6, the bearing retaining ring 10 is inserted by screwing the bearing retaining ring 10 wherein the external threaded portion 10b is placed in threaded engagement with the complementary internal threaded portion

6b.

The raised lip portion 10a engages an internal surface of the hub 6c. A drill (not shown) can then be used to drill through the plurality of recesses 10c and into corresponding points on the internal surface of the hub 6c. Taps 13 are inserted through the recesses 10c and the drilled holes to secure the bearing retaining ring 10 to the hub 6 thus securing the bearing assembly 1 within the hub 6. Alternatively the bearing retaining ring 10 can be secured to the hub 6 by suitable glues such as Locktite™.

Seals 12 are placed between the bearing retaining ring 10 and end caps 7 to protect the internal components of the cutter from contamination from the outside environment. The seals 12 can also urge a better fit between the components.

In order to assemble the cutter, the integral bearing assembly 1 is pressed into the hub 6 using a hydraulic press (not shown).

An end cap 7 is then installed on to the shaft 8. Seals can then be inserted in the end cap 7 and hub 6. The hub 6 with the secured bearing assembly 1 is then pressed on to the shaft 8 by use of a hydraulic press.

The bearing retainer ring 10 is then located between an end cap 7 and the annular hub 6. Initially the bearing assembly 1 is placed within the hub 6 wherein a portion of the bearing assembly 1 engages the ledge 6c and prohibits the bearing assembly 1 from passing through the hub. The bearing retaining ring 10 is then inserted by screwing the bearing retaining ring 10 wherein the external threaded portion 10b is placed in threaded engagement with the complementary internal threaded portion 6b.

The bearing retaining ring 10 can be placed within the hub by a retaining tool 20. As shown in Figure 4, the retaining tool 20 comprises a circular engaging element 21 with a plurality of projections 22 and a cross-sectional handle 23. The plurality of projections are locatable within complementary recesses 10c. The handle 23 can then be rotated to facilitate the threaded engagement between the bearing retaining ring 10 and the annular hub 6.

The raised lip portion 10a engages an internal surface of the hub 6c. A drill (not shown) can then be used to drill through the recesses 10c on to coπesponding points on the internal surface of the hub 6c. Taps 13 can be inserted through the drilled holes to secure the bearing retaining ring to a planar surface of the hub thus securing the bearing assembly within the hub.

Alternatively the bearing ring can be secured to the hub by suitable adhesive such as Locktite™. Seals are then inserted into the bearing retainer ring 10 and end cap 7. The remaining end cap 7 is screwed on to the shaft 8 as tight as possible and secured with a locking pin (not shown). The cutter ring 9 is then added to the semi-assembled cutter unit and secured with a cutter retaining ring 9. The assembled cutter can then be placed in the cutting head.

Investigations indicate that the preferred embodiment and associated method of assembly exhibit some advantages over cutters incorporating known bearing assemblies. For example, the pressing of the bearing assembly either into the hub or over the shaft is effectively done once, rather than twice and from one side only. The entire bearing assembly may be inserted onto the central shaft from one side as opposed from two sides.

Furthermore, no initial disassembly of the cutter during the assembly procedure is generally required. There are less components to inspect and assemble during maintenance of the cutter.

Furthermore, based on demonstrated models, it is expected that the bearing may last longer than a two single bearing arrangement.

Furthermore, the risk of human error in bearing master spacer measurements and subsequent spacer thickness calculations, pre-loading and torque settings, si partially reduced as these tasks are not required.

The word 'comprising' and forms of the word 'comprising' as used in this description does not limit the invention claimed to exclude any variants or additions.

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A cutter for insertion on a cutter head comprising:

(a) a bearing assembly comprising:

(i) an external integral annular cone; (ii) a pair of opposed internal annular cups located in and bearing upon the cone whilst being coaxial therewith; and

(iii) an annular spacer located between the opposed cups to maintain those cups in a predetermined location relative to the cone;

(b) an annular hub having a central recess into which the bearing assembly is releasably inserted;

(d) a cutter ring releasably located on the external circumference of the hub

2. The cutter according to claim 1 wherein the hub comprises an internal ledge or step for decreasing the internal diameter of the hub, the ledge engaging a portion of the bearing assembly to accommodate the bearing assembly within the hub.

3. The cutter according to claim 1 wherein the annular spacer is of a pre-calibrated thickness suitable to maintain appropriate spacing between the pair of internal cups.

4. The cutter according to claim 1 wherein bearing mechanisms are locatable between the cone and the cups.

5. The cutter according to claim 4 wherein said bearing mechanisms comprise toller means.

6 The cutter according to claim 5 wherein the roller means is selected from the group comprising taper rollers, rollers, or balls.

7. The cutter according to claim 5 wherein the roller means is spaced apart by one or more cages or separators.

8. The cutter according to claim 1 wherein the hub comprises an external circumferential groove in which the cutter ring is locatable.

9. The cutter according to claim 1 wherein the cutter further comprises a retainer to retain components of the cutter in position.

10. The cutter according to claim 9 wherein the retainer comprises a cutter retaining ring locatable on the hub and capable of being wedged in registry with the hub to maintain an interlocking fit between the cutter ring and the hub.

11. The cutter according to claim 9 wherein the retainer comprises a pair of annular end caps locatable on the central shaft in registry with the hub and bearing assembly, the annular end caps locatable on opposite sides of the hub.

12. The cutter according to claim 10 further comprising at least one bearing retaining ring locatable between an annular end cap on one side of the hub and the bearing assembly.

13. The cutter according to claim 12 wherein the bearing retaining ring comprises an elongated lip portion capable of engaging an internal surface of the hub.

14. The cutter according to claim 13 wherein the elongated lip portion comprises a plurality of recesses wherein the plurality of recesses provide access points to corresponding points on the internal planar surface of the hub to allow for the insertion of complementary taps through the recesses to secure the bearing retaining ring to a planar surface of the hub.

15. The cutter according to 14 wherein the bearing retaining ring further comprises a threaded external portion capable of threadingly engaging a complementary threaded portion circumscribed on a portion of the hub.

16. The cutter according to claim 12 wherein the bearing retaining ring is secured by adhesive.

17. The cutter according to claim 1 wherein seals are incorporated within the cutter to protect the components of the cutter from contamination from the outside environment.

18. A method for assembling a cutter according to any preceding claim comprising the steps of:

(a) locating the bearing assembly in the hub;

(b) passing the central shaft through the bearing assembly; (c) locating the pair of opposed end caps on the shaft on either side of the assembly to engage the hub; and

(d) locating the cutter ring on the external circumferential surface of the hub.

19. The method according to claim 18 comprising the further steps of:

(e) inserting retaining means; and/or (f) inserting seals, into the cutter assembly.

20. The method according to claim 18 wherein step (a) and step (b) are performed by use of a hydraulic press.

21. The method according to claim 19 comprising the further step (g) of inserting a bearing retaining ring.

22. The method according to claim 21 wherein step (g) is performed by use of a retaining tool.

23. A retaining tool for use in the method according to claim 22 wherein the retaining tool comprises a circular engaging element with a plurality of projections and a cross-sectional handle, the plurality of projections being locatable within complementary recesses located on the bearing retaining ring, the handle being capable of rotational movement relative to the bearing retaining ring and annular hub to facilitate the threaded engagement between the bearing retaining ring and the annular hub.

24. A method for assembling a cutter according to claim 15 comprising the steps of:

(a) locating the bearing assembly into the hub;

(b) passing the central shaft through the bearing assembly;

(d) drilling holes through the plurality of recesses and into corresponding points on the internal planar surface of the hub;

(e) inserting a retaining tool according to claim 23 wherein the plurality of projections are located within complementary recesses located on the bearing retaining ring,

(f) rotating the handle of the retaining tool relative to the bearing retaining ring and annular hub to facilitate a threaded engagement between the bearing retaining ring and the annular hub; and

(g) locating the cutter ring on the external circumferential surface of the hub by wedging the ring in registry with the hub.

25. The method according to claim 25 further comprising the step of inserting taps through the recesses and drilled holes to secure the bearing retaining ring to a planar surface of the annular hub.