Abstract
A raise boring head for rotary boring in rock having a main body mountable at a drive shaft in which a mount face provides a supporting surface for a plurality of saddles that mount, in turn, respective roller cutters. At least one guide block is attached to the main body to project upwardly from the mount face and includes at least one guide face to facilitate the transport of cut material away from the mount face.
Claims
1. A raise boring head for rotary boring in rock comprising: a body arranged to be mounted at a drive shaft, the body having a planar mount face extending radially outward from the shaft; a plurality of channels extending axially through the body from the planar mount face to a rear face of the body to divide the planar mount face into a plurality of spokes, each of the plurality of spokes having a first end adjacent the drive shaft; a plurality of saddles provided on the spokes of the mount face adjacent the channels, the saddles being arranged to rotatably mount respective roller cutters at the body; and at least one guide block attached to at least one of the plurality of spokes and projecting from the planar mount face at a position between the first end of the at least one spoke and a respective saddle so as to be adjacent or spaced apart from the saddles, the at least one guide block having at least one guide face aligned transverse to the mount face and arranged to transport cut material away from the mount face, wherein the at least one guide block is separate from and formed non-integrally with the saddles.
2. The boring head as claimed in claim 1, wherein the at least one guide face is generally planar and inclined relative to the mount face or is curved relative to the mount face.
3. The boring head as claimed in 1, wherein the mount face extends generally perpendicular to the drive shaft.
4. The boring head as claimed claim 1, further comprising at least one attachment bolt to secure the at least one guide block to the mount face.
5. The boring head as claimed in claim 1, wherein the at least one guide block is secured to the mount face via weld material.
6. The boring head as claimed claim 1, wherein the at least one guide block projects from the mount face by a distance that is less than a distance by which at least some of the saddles project from the mount face.
7. The boring head as claimed claim 1, wherein the at least one guide block projects from the mount face by a distance that is less than a distance by which each of the roller cutters project from the mount face.
8. The boring head as claimed in claim 1, wherein the at least one guide block is positioned at the mount face adjacent an open end of a respective channel to deflect cut material into the channel for transport from the mount face to the rear face.
9. The boring head as claimed claim 1, wherein the at least one guide block is positioned at the mount face radially inside the saddles.
10. The boring head as claimed in claim 1, wherein the at least one guide block has a geometry of a triangular prism.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:
(2) FIG. 1 is a schematic illustration of raise boring apparatus to create a borehole between a first and a second underground location using a boring head that mounts a plurality of roller cutters;
(3) FIG. 2 is a perspective view of a main body of the boring head of FIG. 1 mounting a plurality of saddles that in turn mount the roller cutters (removed for illustrative purposes) and a pair of guide blocks to facilitate the discharge of cut material away from the boring head during cutting according to a specific implementation of the present invention;
(4) FIG. 3 is a magnified perspective view of the guide blocks and a mount face of the main body of FIG. 2;
(5) FIG. 4 is a further perspective view of the main body of FIG. 3 with the saddles removed for illustrative purposes;
(6) FIG. 5 is a perspective view of one of the guide blocks of FIG. 4;
(7) FIG. 6 is a side elevation view of one of the guide blocks, saddles and roller cutters attached to the mount face of the main body of FIG. 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
(8) Referring to FIG. 1, raise boring apparatus comprises a raise boring head indicated generally by reference 105 mounted at one end of an elongate drive shaft 104 that is in turn rotatably driven by a drive rig 103. Rig 103 according to the example illustration is mounted at a first underground location 101 being separated from a second underground location 102 by a layer of rock 100. A pilot borehole 106 is formed within rock 100 as an initial pilot drilling operation using a pilot bit (not shown) attached to the end of drive shaft 104 (typically formed from end-to-end threaded rods). Following the creation of the pilot bore 106, the pilot bit is replaced at the end of the shaft 104 by raise boring head 105 having an appreciably larger diameter than the initial pilot bit so as to create a larger diameter bore 109. Both shaft 104 and boring head 105 are mounted centrally on longitudinal axis 111 such that the boring head 105 projects radially outward from axis 111 by a predetermined radius to achieve the desired diameter of bore 109. Boring head 105 comprises a main body 110 that mounts a plurality of saddles 107 that in turn mount respective roller cutters 108. As shaft 104 is rotated via rig 103, main body 110 is configured to rotate with each cutter 108 also rotating independently to cut into the rock 100 as the shaft 104 is retracted axially towards rig 103 and the boring head 105 raised vertically into the rock 100 from the second location 102 to first location 101.
(9) Referring to FIG. 2, main body 110 is formed as an extendable or modular reaming head in which a central section provides a mounting for side extensions or wings (not shown). In particular, main body 110 comprises sidewalls 204 and respective attachment couplings 203, 210 positioned to secure the head extensions (not shown) against or opposed to sidewalls 204 so as to extend the diameter of the boring head 105 relative to axis 111. Main body 110 comprises a planar mount face indicated generally by reference 200 that comprises a cylindrical through bore 201 (defined by a circular opening 208 within mount face 200) centred on axis 111 and extending axially through the main body 110 from the mount face 200 to a rear face 202 that mounts drive shaft 104 at boring head 105. Mount face 200 also comprises a plurality of openings 211 distributed around central bore 201 that at least partially define channels 205 that also extend from mount face 200 to rear face 202. Channels 205 are open at both faces 200, 202 to allow the downward discharge (under gravity) of cut material from the mount face 200 to the rear face 202 to then fall below boring head 105. Accordingly, mount face 200 is divided into a plurality of spokes 209 extending radially from an outer perimeter edge 207 to the central bore 201.
(10) Each spoke 209 provides a mounting region for one or a plurality of saddles 107 that each mount respectively a roller cutter 108 (removed from FIGS. 2 and 3 for illustrative purposes). Each saddle 107 projects upwardly from mount face 200 in a direction of axis 111 and drive shaft 104. According to the specific implementation, a guide block 206 is also attached to mount face 200 at a radially inner region of two diametrically opposed spokes 209. Guide blocks 206 are positioned radially inside respective saddles 107 so as to be positioned radially intermediate saddles 107 and central axis 111 (and drive shaft 104) during use.
(11) Referring to FIGS. 3 to 5, each guide block 206 is formed as a single piece body in a form of a triangular prism having a base surface 400 mounted in contact with mount face 200 of main body 110. A pair of substantially planar inclined guide faces 300a, 300b project upwardly from base surface 400 and together define an apex or ridge 500. A pair of generally vertical side faces 501 extend perpendicular to the base surface 400 at each lateral side of the inclined guide faces 300a, 300b. Accordingly, with guide block 206 secured in position at mount face 200, guide faces 300a, 300b extend transverse to the generally horizontal planer mount face 200. According to the specific implementation, the elongate apex 500 is aligned with the radially extending spoke 209 on which the guide block 206 is mounted and also a corresponding rotational axis (also extending in a radial direction from axis 111) about which the roller cutter 108 is configured to rotate when mounted at saddle 107 positioned radially outside and adjacent guide block 206 on the same spoke 209. Accordingly, guide faces 300a, 300b are inclined upwardly from the lateral sides 303 of spoke 209 such that cut material is configured to slide downwardly over faces 300a, 300b to then fall into each channel 205 to each lateral side 303 of spoke 209.
(12) Each guide block 206 comprises a pair of through bores 301 that extend from each respective guide face 300a, 300b to base surface 400 so as to receive attachment bolts (not shown) to releasably attach each guide block 206 to main body 110 via mount face 200. The bolts (not shown) are secured within threaded bores 401 extending axially into main body 110 from mount face 200. Corresponding threaded bores 402 are also provided on each spoke 209 so as to releasably attach saddle 107 via separate corresponding bolts received through respective bores 302 formed through a base region of saddle 107.
(13) By configuring mount face 200 with a plurality of threaded bores 401, 402 at different locations, and via the appropriate attachment bolts (not shown) guide blocks 206 and saddles 107 are independently and interchangeably mounted at main body 110.
(14) Referring to FIG. 6, each guide block 206 projects upwardly from mount face 200 by a distance A corresponding to the vertical height of apex ridge 500 from mount face 200. Each saddle 107 comprises a pair of upstanding arms 600 to receive roller cutter 108 therebetween for rotation about axis 603. Each arm 600 comprises an uppermost end 601 that extends vertically above mount face 200 by a distance B. Roller cutter 108 comprises a plurality of cutting inserts 602 that represent the leading uppermost components of cutter 108 being configured to engage and cut the rock 100. Cutting inserts 602 are separated by a maximum distance C from mount face 200 as the cutter 108 rotates about axis 603. It is desirable that guide block 206 is mounted (in the axial height direction) below the uppermost cutting region of the cutters 108 and the uppermost end 601 of saddles 107 so as to avoid damage to the guide block 206 due to contact with the rock face 100 and a reduction in the cutting efficiency and boring rate of head 105. Accordingly, apex 500 is positioned in the lower half of the height of saddle 107 and significantly below the upper cutting region of cutter 108. In particular, distance A is approximately 30 to 40% of distance B and 25 to 37% of distance C. Additionally, according to the specific implementation, a length of guide blocks 206 is less than a corresponding length of each saddle 107 in a radial direction of spoke 209. In particular and according to the specific implementation, a length of guide block 206 is slightly greater than half of the length of saddle 107. According to the specific embodiment of FIGS. 2 to 6, guide blocks 206 are configured to prevent accumulation of debris at the radially inner region of the mount face 200 by directing the cut material into the channels 205 via guide faces 300a, 300b.
(15) According to further specific embodiments, guide blocks 206 may comprise generally curved guide faces 300a, 300b where the curvature may be concave or convex in the axial direction perpendicular to mount face 200. Additionally, each guide block 206 may comprise a single guide face (300a or 300b) or may comprises a plurality of guide faces where the guide block is formed as a polyhedron. According to further embodiments, guide blocks 206 may be removably positioned towards the perimeter edge 207 so as to avoid the accumulation of debris material at the perimeter of the main body 110 and between the main body 110 and an extension body (not shown) attached at one or more of the sidewalls 204.
(16) The present reaming head may comprise a plurality of the same of different shaped guide blocks 206 and may comprise a symmetrical or asymmetrical distribution of guide blocks 206 at mount face 200.
