Abstract
A wear support assembly includes a wear pad arranged on top of a support plate, wherein the support plate has a lower surface for connecting to a raise boring tool and both the wear pad and the support plate have at least one hole for receiving a bolt to connect the wear pad to the support plate. Also, a raise boring tool for raise boring operations includes a reamer head having a body, a plurality of roller cutters connected to the body using a holder, a nose or drive stem connected the body, and at least one wear support assembly, wherein each support plate is connected directly to the raise boring tool and each wear pad is radially or perpendicularly bolted to each support plate.
Claims
1. A wear support assembly comprising a wear pad arranged on top of a support plate, wherein the support plate has a lower surface for connecting to a raise boring tool, both the wear pad and the support plate having at least one hole for receiving a bolt to connect the wear pad to the support plate.
2. The wear support assembly according to claim 1, wherein the support plate includes a back end step for securing the wear pad to the support plate.
3. The wear support assembly according to claim 1, wherein the support plate has a stop bolt for securing the wear pad to the support plate.
4. The wear support assembly according to claim 1, wherein the support plate includes a side step for securing the wear pad to the support plate.
5. The wear support assembly according to claim 1, further comprising a key located on the support plate.
6. The wear support assembly according to claim 1, wherein the at least one hole comprises more than two holes, each receiving a bolt.
7. The wear support assembly according to claim 1, wherein the at least one hole has two diameters, wherein a larger diameter hole is located nearer an upper surface of the support plate and a smaller diameter hole is located nearer a lower surface of the support plate.
8. The wear support assembly according to claim 1, wherein the upper surface on the support plate and the lower surface on the wear pad are both flat.
9. The wear support assembly according to claim 1, wherein the upper surface on the support plate and the lower surface on the wear pad are both convex.
10. The wear support assembly according to claim 1, wherein the wear pad is hard facedwith tungsten carbide.
11. A raise boring tool for raise boring operations comprising; a reamer head having a body; a plurality of roller cutters connected to the body by a holder; a nose or drive stem connected to the body; and at least one wear support assembly according to claim 1, wherein each support plate is connected directly to the raise boring tool and each wear pad is bolted to each support plate.
12. The raise boring tool according to claim 11, wherein at least one wear support assembly is positioned radially on the body of the reamer head.
13. The raise boring tool according to claim 11, wherein at least one wear support assembly is positioned on the nose of the reamer head.
14. The raise boring tool according claim 11, wherein at least one wear support assembly is positioned on the drive stem.
15. The raise boring tool according to claim 11, wherein the nose is integrated with the body.
16. The raise boring tool according to any of claim 11, wherein the nose is detachable from the body.
Description
BRIEF DESCRIPTION OF THE DRAWING
[0028] A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings:
[0029] FIG. 1: Perspective view of a raise boring tool having a reamer head with two roller cutters and the wear support assembly positioned on the body of the reamer head.
[0030] FIG. 2: Perspective view of a raise boring tool having a reamer head with three roller cutters and the wear support assembly positioned on the body of the reamer head.
[0031] FIG. 3: Perspective view of a raise boring tool having a reamer head with two roller cutters and the wear support assembly positioned on the nose of the reamer head.
[0032] FIG. 4: Perspective view of a raise boring tool having a reamer head connected to a drive stem and the wear support assembly positioned on the drive stem.
[0033] FIG. 5: Perspective view of the wear pad.
[0034] FIG. 6: Perspective view of the support plates with a back end step.
[0035] FIG. 7: Perspective view of an embodiment of the present invention wherein the support plate has a back end step and a stop bolt.
[0036] FIG. 8: Perspective view of an embodiment of the present invention wherein the support plate has a back end step and a side step.
[0037] FIG. 9: Perspective view of an embodiment of the present invention wherein the support plate has a key.
[0038] FIG. 10: Perspective view of an embodiment of the present invention wherein the support plate has a flat upper surface.
DETAILED DESCRIPTION
[0039] FIG. 1 shows a raise boring tool 6 having reamer head 8 comprising a body 16 and a plurality of roller cutters 14 which are rotatably mounted on the body 16 using holders 15 (otherwise known as fasteners, tool holders or saddles) and a nose 12 having a threaded connection for attachment to a stabilizer pipe and pilot bit (alternatively a bull nose fitted). The holders 15 are mounted or integrated on the body 16. The nose 12 can either be integrated with the body 16 or a separate attachable part.
[0040] The nose 12 may be a bull nose and form the front end of the reamer head 8 or it may have a threadedly connection for attachment to a stabilizer pipe and pilot bit. Alternatively, a drive stem 10 may be attached to the body 16 of the reamer head 8 instead of the nose 12, as shown in FIG. 4.
[0041] At least one support plate 20 is attached onto the raise boring tool 6 in a region where wear protection is needed. The support plate 20 has lower surface 46 for connecting radially to a raise boring tool 6, which is preferably curved but could be flat. Radially means perpendicular to a centre line 56 of the raise boring tool 6. Preferably, the support plate 20 is welded onto the raise boring tool 6. Alternatively, the support plate 20 could be bolted or secured in any other suitable way onto the raise boring tool 6. The support plate(s) 20 could be fitted to the body 16 and / or the nose 12 of the reamer head 16 and / or could be fitted to the drive stem 10 or in any other position where wear protection is required. A wear pad 22 is then radially or perpendicularly bolted to the support plate 20 using a plurality of bolts 24 with respect to the lower surface 40 of the wear pad 22. Preferably, more than two bolts 24 are used, such as four bolts 24. For example, there could be one bolt 24 in each of the corners of the wear pad 22. The support plate 20 and the wear pad 22 together form a wear support assembly 4. FIG. 5 shows the wear pad 22 in more detail. Typically, the support plates 20 and wear pads 22 have an oblong shape, but they could be any other suitable shape and have holes 36 drilled into them for receiving the bolts 24. The bolts 24 may extend through the wear pad 22 into the support plate 20 or they may also extend through the support plate 20 into the body 16 or the nose 12 of the reamer head 8 or into the drive stem 10. The wear pads 22 have a lower surface 40, that contacts an upper surface 38 on the support plate, and an upper surface 42, that is exposed to the rock being drilled. The holes 36 project in a direction perpendicular to or radially with respect to the lower surface 40 of the wear pads 22. The wear pads 22 are made from a wear resistant material, for example the wear pads 22 could be made from a mild steel or a hard steel. Preferably, the upper surface 42 of the wear pad is hard faced, for example with tungsten carbide or any other suitable wear resistant material. Alternatively, cemented carbide inserts could be added to the wear pads 22 to increase their wear resistance. Preferably, the bolts 24 are countersunk into the wear pad 22 to reduce their exposure to wear. This can be achieved by drilling holes 36 in the wear pad 22 for receiving the bolts 24 having two diameters, wherein the larger diameter hole is nearer the upper surface 42 and the smaller diameter hole is nearer the lower surface 40. The area of the wear pad 22 can be increased to any suitable size for the specific raise boring tool 6 to provide addition wear protection and stability.
[0042] The wear support assembly 4 can be attached to any part of the raise boring tool 6 where wear protection is required. FIG. 1 shows an example where the raise boring tool 6 is a slot raiser and where the wear support assemblies 4 are attached to the body 16 of the reamer head 8 that has two roller cutters 14 and a nose 12 with a threaded connection. When there are only two roller cutters 14, the wear support assemblies 4 are particularly important for adding stability to the drilling operation. FIG. 2 shows an example of a slot raiser where the wear support assemblies 4 are attached the body 16 of the reamer head 8 that has three roller cutters 14 and a nose 12 with a threaded connection. FIG. 3 shows an example of a slot raiser that has two rollers cutters 14, the nose 12 is a bull nose and where the wear pads 22 and support plates 20 are attached the nose 12 of the reamer head 8. FIG. 4 shows an example of a raise boring tool 6 wherein the reamer head 8 is attached a drive stem 10 and wherein the wear pads 22 and support plates 20 are attached to the drive stem 10. In this case the drive stem 10 connects the reamer head 8 to a rig (not shown) and assists in stabilising the drilling operation. It should be understood that the invention could be applied to any other type of raise boring tool 6 or equipment and the wear support assembly 4 could be positioned on any part of the reamer head 8 or drive stem 10 where wear protection and / or stability is required.
[0043] FIG. 6 shows that the support plate 20 could have a back end step 28, positioned to absorb force from the forward drilling direction and keep the wear pad 22 held rigidly in place. The backend step 28 is positioned on the axially opposite side of the support plate 20 compared to the roller cutters 14. The back end step 28 could be milled into the support plate 20 such that the support plate 20 is a one piece body. Alternatively, the back end step 28 could be bolted or welded onto the support plate 20, such that the support plate 20 is a two or more piece body. A step is section of the support plate 20 which has an increased thickness, with a first side 50 that is perpendicular to the upper surface 42 for abutment with the wear pad 22 and a second side 52 that is parallel and raised in respect to the upper surface 42.
[0044] FIG. 7 shows that a stop bolt 32 could also be secured to the rotationally trailing side of the support plate 20, such that the wear pad 22 is able to press against it. The rotationally trailing side is the side that is opposite to the side that contacts the rock first as the reamer head 8 is rotating. The stop bolt 32 acts as a support for the wear pad 22 to absorb some of the rotational force applied from the drilling operation and aid in keeping the wear pad 22 held rigidly in place. The back end step 28 and the stop bolt 32 can either be employed on their own or in combination.
[0045] FIG. 8 shows an alternative embodiment of the support plate 20, wherein the stop bolt 32 has been replaced with a side step 30. The side step 30 could be employed in combination with the back end step 28 or on its own. The side step 30 is positioned on the rotationally trailing of side of the support plate 20, in other words on the side of the support plate 20 that contacts the rock first as the reamer head 8 is rotating. Alternatively, the side step 30 could be positioned on the rotationally leading side of the support plate 20. There could also be two side steps 30 on the support plate 20, one of each side of the wear pad 22, in other words on both the rotationally trailing and rotationally leading sides, so that the wear pad 22 is supported in both rotational directions. The side step 30 could either be welded, milled or bolted in position. The side step 30 could be employed either on its own or in combination with a back end step 28.
[0046] A step is section of the support plate 20 which has an increased thickness, a first side 50 that is perpendicular to the upper surface 42 for abutment with the wear pad 22 and a raised side 52 that is parallel to the upper surface 42.
[0047] FIG. 9 shows an alternative embodiment wherein there is a key 34 positioned on the support plate 20. The key 34 is fitted in a slot between the wear pad 22 and the support plate 20 to relieve the bolts 24 from stresses. The key 34 could be any suitable shape, for example in the form of a pin, oblong or half-moon. The key 34 could be pressed in place or bolted in place using small screws. The key 34 could be countersunk into a recess on the lower surface 40 of the wear pad 22. The key 34 could be used on its own or in combination with any of the previous embodiments disclosed hereinabove.
[0048] The upper surface 38 of the support plate 20 and the lower surface 40 of the wear pad 22 that are pressed against each other could either both be convex or curved, as shown in FIGS. 6-9.
[0049] FIG. 10, shows an alternative embodiment, wherein the upper surface 38 of the support plate 20 and the lower surface 40 of the wear pad 22 are both flat and fitted so that they are parallel to one another.
