CA1057277A - Replaceable drive stem for a raise drill - Google Patents

Abstract

Abstract A raise type of earth boring drill in which the cutter assembly is detachably secured to the drive stem to permit replacement of the stem. The stem slidably engages a central opening in the cutter assembly, the cutter assembly engaging a shoulder on the stem which carries axial loads in the drill. The cutter assembly is detachably anchored by a plurality of bolts to a torque plate attached to the end of the stem for transmitting torque load to the cutter assembly, the bolts clamping the cutter assembly against the shoulder.

Description

7~77 REPLACEABLE DRIVE STEM FO:R A RAISE DRILL
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Field of the Invention This invention relates to a replaceable item for a raise-~ . ~
type earth boring drill in which the stem is removably attached S to the cutter assembly.

Background of the Invention ; , , :
It is well known in the mining art to utilize a raise type of earth boring drill to form vertical shats between mining tunnels at different levels. One such type of raise drill is described, for example, in U.S. Patent No. 3,675,729.
,- , i The tool is used by first drilling a small pilot hole between ~ the two levels. A drill string is then lowered through the 1 .- . .
pilot hole from rotary drive equipment at the upper level and a raise drill tool is attached at the lower level to the drill 15 ~ string. The drill is then drawn upwardly while simultaneously ~ : :
~;~ being rotated by the drill string, the drill reaming out the hole to the desired diameter. In an exemplary embodiment the .
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~L~57Z77 ~ pilot hole may be 11" in diameter an~ the raise drill reams : out a hole 6' in diameter.
~ he stem of the raise drill, which is slightly smaller in diameter than the pilot hole, acts as a guide for the raise drill. ~owever, the stem is subjected to con-siderable wear due to abrasive.contac~ with the surrounding earth formation and, at the same time, is subjected to - considerable stress both of tension due to the lifting force imparted to the drill, twisting due to the torque applied to 0 the drill, and bending due to unequal loadi~g around the circumference of the drillO Usually a protective layer of hard facing is applied to the drill stem to give added protec~
~ . tion against the abrasive action of the surrounding earth ~ `.
:~ materials.
Although it is common to provide such drills with replaceable rotary cutters, generally the stems have not been : .
made readily replaceable~ Thus when the stem becomes WQrn or fails in operation, replacement of the drill tool is required. -While the replacement of the stem portion of a raise drill 20 has heretofore been proposed; a5 in ~ atent Numbers 3,659,659 ~ ~ -. ~ and 3,750,767, such known designs have relied on welded or threaded joints to transfer the torque and longitudinal .1~ ~orces from ~he stem to the cutter assembly. The raise drill ~: ` &~.g ' "' . , .
: ~ in~Patent No. 3,750,767 has a steep tapr between the stem 25 and cutter assembly~ Special cutting, pulling, or torquing tools are then required to disassemble and remove the stem .~
from the cutter assembly, which tools are not always readily : ~:
availa~le in the mining tunnels where the equipment is being used. Furthermore such know~ drills do not provide any means ' 30 for directing cooling or lubricating fluids through the center . `

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.;, ~ C957~7~7 of the stem to the cutters in the cutter assembly, which presents a unique problem where the stem is to be made separable from the cutter assemhly.
Summary of the Invention ~:
In accordance with ~he present invention there is provided a replaceable drive stem for a raise drill comprising: .
; a central shank portion including means at its upper end for 1 connection to a drill string for ~ransmitting tension and torque; - ;
a lower end portion on the shank portion having a larger diameter than the upper end of the shank portion forming an upwardly facing peripheral shoulder; ;
I a torque transmitting plate attached to the lower end :: poxtion of the shank portion~ the plate extending radially beyond .
` ~ the perimeter of the shank portion and including means for transmitting torque; and a plurality of coun~erbores~extending into the shank~portion above the peripheral shoulder for receiving a cutter mounting ~;` shaft in each of such counterbores, the counterbores being :~
~ spaced axially from the shoulder towarcls the upper end of the ,~:20: shank portion.

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In a raise drill o~ the inven~lon i~cluding a replaceable s~em of the inver~tion the stem is easily removed from the cutter assembly to provide simple replacement in he field. Separate connections between the cutter ~s~embly and the ~tem are provided s for a~spectively transferrirlg ~he prisacipal axial load ans31 the ! principal torque load ~etween the stem and the cutter as embly.
Disassembly i~ effec~ed by removal o~ several ~tandard bol ^~ :
whicho while loc~ing the cutter as;sen~ly and the ~tem ~oge~her, do no~ themselYes trans~er any o~ the axia~ load between the 10 ~em and the cut~er assembly and little, if any, of the toXque ~: ~oad. A simple fluid coupling betweer; ~he cuæter assembly and he drive s em connects a cerltxal pas~;age in ~he stem to a fluid ma~ifold in t;:he cu~er asser~bly from wh~ch coolant fluid unde I pres~ure can be applied to the indiviclual cu~ter elemen~
., 15 Thi~ i~ accomplished, in brief, by providing a raise rill comp~ising a ~tem having means at ~ts upper Qnd for ; coamection to a drill sgring. A ~orque pla~:e i~ rigidl3,~ secured to the lower end of the ~temO A ~eparate cutter assembly i3~clud a frame plate having a cen~ral hole th~ough which the upp2~ .e~d ~ :
`20 vf the stem i~ sertedO me ~tem ba~ an upwardly faoi~g ~: ~ shou~der wAich engag~s t}~ ~rasnei :plate arov~d the ce2~al hole `
Eor ~transferrl~g 1:h8 ax~al ~d~ ng laaa beitween the ~ la~e ., :~
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~5~77 and the stem. A plurality of rotary cutters are mounted on the frame plate around the centr~l hole. The cutter assembly also includes a flange plate which engages the torque plate wAen the :;
cutter assembly is in position against the shoulder of the stem.
Drive pins extend between the torque plate and flange plate to ~ -~ransfer the torque load between t~e stem and cutter assembly.
Bolts clamp the flange plate to the torque plate to lock the c~tter assembly in position.
Description o f th~
~ 10 For a more complete unders~anding of the invention refer '~ ence should be made to the accompanying drawings, wherein:
,: ~ FIG. 1 is a plan view of the raise drill; and -FIG. 2 is an elevational view partially in section with ' ~ the cutters proje~ted in th~ same plane and with a lower stage lS ~ ~added.
Det~iled De~-ri~b~oo ` Referring to t~e drawings in detail, the numeral 10 ~:
indicates generally the control shank of the drive shaft or stem :-of the roise drill. The upper end of the stem shank is provided ~ ~:
~,~ . 20 ~ with a tapered thread 12 by which it can be threaded into a , ~ .
tandard drill string through which the raise drill is driven by applying tension and toxgue thereto. The stem include~
fluted portion 14 having hard facing strips 16 welded in place ,, - ~ , ~ , :
to provide protection for the stem where it enters the pilot ;, 25 hole which is being reamed out by the raise drill : -~. The lower end o~ the stem shank, as in~icated at 18, :i is welded or otherwise rigidly attached to a transverse torque plate 20. ~he t~rque plate 20 trans~ers tor~ue from the shank of the stem 10 to a detachable rotary drill bit assembly, indicat d ' ' : ~ ' ' , . ...

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~6~57'~7 .' 1 generally at 22. The ro~ary drill bit assembly, as herein-after described in detail, fits down over the upper end of the stem 10 and is bolted to the torque plate 20. ~he stem 10, toge~her with the torque pla~e 20, can be replaced as a . S unit by detaching the torque plate 20 from the assembly 22 and withdxawing the stem.
The drill bit assembly 22 includes a main frame ~ plate 24 having a central opening ~6 which has a diameter ., only slightly larger than the central shank portion ~B of the ; 10 stem 10. The central shank portion 28 is of a smaller ~ :
~ . diameter than the lower end 18 of the stem 10, forming an ~ :
.' . .upwardly facing peripheral shoulder.30 against which the . ~ ~ .
margin of the hole 26 in ~he main ~rame plate 24 ~its when the assembly 22 is in the assembled positi`on with the stem 10.

~The frame plate 24 is part of a frame assembly which . includes a flan~e plate 32 in the form of a ring ha~ing a central opening 34 which is slightly larger in diameter than the lower end 18.of ~he stem 10. The flange plate 32 i~
. rigidly secured in parallel relation to the main frame plate : :~

24 ~y a cylindrical collar.36 which is concentric with the ope~ings 26 and 34. The plates 24 and 32 are also ~oined by ~ ;
. four radial plates, each of which include an inner section 38 ::~
positioned on tha inside of the collar 36, and an outer section 40 positioned on the outside of the collar 360 The ~5 collar 36 and inner and outer radial plate sections 38 and : :
40 are welded ~o the frame plate 24 and flange pla~e 32 ~o ;~ form a unitary frame structure for the assembly 22.
Th~ spacing between the parallel plates 24 and 32 is ~ ~uch that when the frame plate 24 engages ~he shoulder 30 the :' 30 flange plate 32 is in close proximity to the ~orque plate 20.
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1 Torque is transferred from the torque plate 20 to the ad~acent flange plate 32 by a pair of drive pins 42. The pins 42 are . anchor~d in the torque plate 20 and en~age ma~ing holes in the i flange plate 32 for locking the two plates against relative rotation. A plurality of bolts 44 extend through aligned holes in the plates 24 and 32 and are held in place by nuts 46. Whe~
. the nuts are tightened on the bolts, the bottom section 18 of the stem 10 is clamped securely ~etween the ~rame plate 24 and the torque plate 20. By this arrangement, most of the axial :-10 load is transferred from the cutter assembly 2-2 to the stem 10 . through the shoulder 30, while the torque load is transferred through the pins 42. No ~orque load is transmitted by the . shoulder and little if any.axial load is transmi~ted by the, torque plate.
Four outer rotary cutter un:i s 48 are mounted on the ; main frame plate 24. Each cutter Ullit includes a mounting :~
yoke ~0 which supports a shaft ~2 on which is j~urnalPd a :~
conicaI shaped rock cutter 54. While the cutters 54 are ; . illustrated fo~ clarity as smooth truncated cones, it will be :~
recognized by one skilled in the art tha~ such cutters have a plurality of hardened steel or tungsten carbide teeth for :
, pulverizing rockO Two similar -intermediate cutter units are also mounted on the main frame plate 24 at a smaller distance ~rom the axis of rotation of the stem, as indicated at 56O
25 As seen n FIG~ 2, the conical cu~ters of the outer units 48 :~ and intermediate units 56 lie tangent to a csmmon conical surface 57 whose axis of rotation corresponds ~o the axis of :~
. the stem 10. ~ :~
,~ In addition, two inner cutter units, indicated : 30 generally at 58, are supported on mounting blocks 60 welded ', _~_ 7~77 to the main frame plate 24. The conical rotary cutter 62 is journaled on a conventional fixed bearin~ shaft 64, one end of which is mounted in a counterbore 66 in ~he stem 10. The stem 10 includes a recess 68 or provi~ing clearance for the inner end o the conical cutter 62. The shaft ~4 and counterbore 66 extend at an angle such that the cutting surface of the inner cutters 62 are tangent to a plane 70 which is perpendicular to the axis .:
of the stem. The outer end o~ the shaft 64 is joined to a mount- :
ing yoke 72 which is removably secured to the mounting blsck 60 ~ .
in a manner to define a generally U-shaped opening between a mounting surface 73 thereof and th~ facing stem recess surface, and ~
to permit the sha~t 64 to ~e inserted into the counterborP- 66. ~ -. To this end, the top of the mounting block 60 is formed with a ~ first flat surface 74 which intersects a second flat sur~ace 76 :15 in a plane parallel-to the xotational axis of the conical cutter n 62~ The surface 74 ac~s a-~ a stop. The yoke 72 has a mating ~` sur~ace 78 which is slidable along the surface 76. The yoke 72 also has a flat surface 80 which is parallel to the stop surface 74.
To insert khe cutter 62 into operating position, the yoke 20~ 72 i~ lowered onto the surface 76 with the surface 80 in contact with the stop surface 74 of the mounting block 60. The inner end of the s~aft 64 1ie~ outside the counterbore 66 when the yoke 72 is in this position. The cutter 62 is then maved axially to slide the shaft 64 into ~he counterbore 66 by sliding the :25 surPace 78 of the yoke 72 inwardly along the surface 76. With the shaft 64 fully inserted in the counterbore 66, a shim ox spacer : ' -~ 82 is inserterl b~tween the surfaces 74 and 80. The yoke 72 is ~:
;~ then anchored in position by a pair of bolts 84 ~hat extend per-pendicular to the sur~aces 74 and 80 through aligned holes in the ~lock 60 and shim 82, ~he inner ends of the bol~ ~hreadedly engaging the yo~ce 72. :

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1 The angle of the bol~s 84 is in a direction to pull downwardly and outwardly on the yoke 72, thexeby securely clamping the yoke 72 ~gainst the inclined surface 76, while at the same time clamping the shLm 82 securely in place.
S The machining tolerances are such that in pulling downwardly . on the yoke 72, the tightening of the bolts 84 tends to cock ~ the sha~t 64 slightly in-the bore 66, thus removing any play : : that might exist between the shaft 64 and the bore 66 that could otherwise be a source of wear. ~he block S0 is 0 provided with a plate 86 which is welded to the block 60 and acts as a lateral stop for absorbing any lateral load . . b.etween the cutter 62 and ~he ~lock 60 resulting from rotation of the stem 10. . .
~our relatively thin, flat rectangular plates 90 ~re S welded inside the collar 36 ~etween the main frame plate 24 . .and flange plate 32 ~o provide a manifold for-a coolant, such ~; .as water, for the rotary cutt~rs. The plates 90 terminate at - the inner radial plate sections 38, the plates 90 fo~ming one ~
wall for fou~ enclosed chambers 92. The fluid communication ~ ;
0 between the chambers is provided by notching the corners of the inner radial plate sections ~8, as indicated at 94O
Fluid is admitted to the ~nterc~nnected chambers 92 by means of a central passage 96 along the axis of the stem 1O. A
~ radial passage 98 receives a fitting 100 on.the outside of .. ~5 the stem 10 t:o which a hose or other flexible fluid coupling ~.
.102 i~ attached. The flexible coupling 102 connects to a :l ~ tu~e section 104 which in turn is connected to a passage 106 ~ -:, ~ through the frame plate 2~ by a fitting 10~. The passage 106 :~ opens into the chamber 92. Thus a coolant fluid can be - 30 pumped through the center of the drill stem into the passage 96 ., . ~

105'727'7 ¦ and radial passage 38 and through the fluid coupling into ¦ the passage 106 for illing the fluid chambers 92.
¦ Outlet passages 110 through the frame platP 24 ¦ intersect with spray passages 112 in the yokes 50, the spray 5 I passages directing the fluid in a spray out ~gainst the ¦ surface of the associated rotary cutters 54. The ~ooling ¦ fluid passes from the chambers 92 to the passages llQ throu~.
¦ openings 114 in the collar 36 ~hrough a passage formed by a recess 11~ in the edge of the outer radial section 40O Cover :101 plates 118 are welded or ~therwise affixed to cover the ~
recess 116 to provide a fluid-tight passage. ~ :
. -~ ~. . ~imilarly, an outlet passage 119 through the frame ~ -: ~ : plate 24 communicates with a passage 120 through the support- ~ ~
. ing yokes of the intermediate cutter units 56 to provide a ~ : :
. coolant spray~for these cutters. - :
The inner cutters 62.are provided with an associated spray unit 122 having a passage 124 whîch communicates with the chamber 92 through a passage 126. ~ removable plug 128 ;~
in the collar 36 may be provided for draining the chamber 92.
8 From the above description it will be recognized that a raise drill is provided in which the stem can be readily replaced with standard wrenches, thus eliminating the need for any speoial cutting or welding equipment. Disassembly ~: : reguires only that the bolts 84 be removed, the shims 82 ~:
removed, and the shaft 64 withdrawn from the bore 66 in the ~ ~.
stem. After the inner cutters 5~ are lifted out, the fluid coupling between the 9tem and chambers 92 can be disconnected, and the nuts 46 and bolts ~4 xemoved. The stem 10 and torque plate 20 can then be separated from the drill cutter ~ssembly 30 22 by sliding the stem out through the openings 26 and 34.
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~57Z77 1 It will be seen ~h~t the axial load is transferred through the shoulder 30 and the torque plate 20. The torque is *ransferred primarily through the dxiYe pins and partly by the journal shaft 64 for the inner cutters which connects at its ends to the stem and the mounting blocks on the frame.
A minor amount of axial load is also carried by the journal shaft 64. No torque load is transmitted by the shoulder.
~nder ordinary circumstances, no axial load is carried by the torque plate. The stem is rigid relative to the cutter ~0 assembly so that the journal shaft 6~ on the inboard ~utters ~-is secured in the bores 66 i~ t~e stem~
In -some cases it is-desired to r~ise drill or ream a hole larger than readily-~ccommodated with a singl~ frame assembly supporting cutters as hereinabove desoribad O A

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second, lar~er diameter frame assembly 130, called a lower stage, can be bolted on the bottom of the above described assembly for reaming larger holes. ~he lower stage assembly 130 includes a pla~e 132 t~at is bolted to the bottom of torque plate 20 by means of th~ bolts 44O The pins 42 ara ~0 also made long enough t~ project ~eyond the torque plate 20 a~d engage holes 13~ in the plate 132. A plurality of cutter assemblies, one of-which is indicated a~ 136, are mounted at circumferentially spaced positions on the plate 132 and are radially outbo~rd of the cutters 48. A ring 140 is secured to the bottom o~ the plate 132 by a pair of concentric collars~
' ~ 14~ and 144 which are welded in place. An annular chamber 146 between the collar~ provides a cooling fluid conduit for ~;
directi~g fluid out through bores 148 associated with each cutter assembly 136. Pluid is coupled fxom the chamher 92 to - 30 the chambex 146 by a suitable fl~id coupling 150. Axial load ' ., .

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1 ¦ to the lower frame assembly is carried by the bolts 44 bac~
¦ to the shoulder 30. The torque plate on the end of the stem ¦ is sandwiched between the smaller upper frame and the larger I lower frame.
:3 ¦ It will be noted that although described in relation ¦ to a raise drill pulled by a drill String through a pilot ¦ hole, principles of this invention may also be applicable to ..
¦ a large reaming drill pushed behind a pilot drill. . :

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Claims (2)

1. A replaceable drive stem for a raise drill comprising:
a central shank portion including means at its upper end for connection to a drill string for transmitting tension and torque;
a lower end portion on the shaft portion having a larger diameter than the upper end of the shank portion forming an upwardly facing peripheral shoulder;
a torque transmitting plate attached to the lower end portion of the shank portion, the plate extending radially beyond the perimeter of the shank-portion and including means for transmitting torque; and a plurality of counterbores extending into the shank portion above the peripheral shoulder for receiving a cutter mounting shaft in each of such counterbores, the counterbores being spaced axially from the shoulder towards the upper end of the shank portion.

2. The replaceable drive stem of Claim 1 further comprising a fluid passage extending longitudinally through the shank portion and open at the top end of the shank portion.