US2865603A - Hydraulically-operated spudding mechanism for cable-tool drills - Google Patents

Description

1958 T. N. HUDSON ET AL 2,865,603

HYDRAULICALLY-OPERATED SPUDDING MECHANISM FOR CABLE-TOOL DRILLS Filed Feb. 8, 1954 L 36(Smumc: VALVE) 27 (R5515 A c5 JAB'IB K5 START VALVE) IIIIIIII/I/A LILJS Tom N- Huvsou,

HERBERT w-Thomsukq ALBERT c. HAl-acH,

INVENTORS.

9 w M 14 71 W HYDRAULICALLY-OHERATED SPUDDING MECHANISM FOR iIABLE-TOQL DRILLS Tom N. Hudson, Milwaukee, and Herbert W. Thornburg and Albert C. Haiscn, South Milwaukee, Wis, assignor to Bucyrns-Erie Company, outh Milwaukee, Wis, a corporation of Delaware, and Tom N. Hudson, Milwaukee, Wis.

Application February 8, 1954, Serial No. 403,693

Claims. cr. 255-40 This invention relates to new and useful hydraulicallyoperated spudding mechanism for cable-tool drills, and constitutes an improvement over the drill shown, described, and claimed in the copending application of one of the three joint inventors of the present invention, said copending application being Serial No. 251,499, now Patent No. 2,749,090, filed October 16, 1951, by Tom N. Hudson, for Cable-Tool Drill, to which copending application reference may be made for anything not fully described and shown herein.

Spudder-type cable-tool drills, per se, are well known in the art. I

In such drills, a rope passes from a winch-drum on the main frame, thence over or under one or more sheaves, one of which is usually at the upper end of a mast, and from this latter sheave vertically downward into the hole which is being drilled in the ground. At the lower end of this rope is a string of drilling tools, terminating in a percussion bit. One of the sheaves, over or under which the rope passes, is reciprocable by appropriate associated means, whereby the bit is rapidly alternately raised and then dropped, to drill the hole, which operation is known in the trade as spudding.

It is the principal object of the present invention to devise an automatically self-synchronizing hydraulicallyoperated cable-tool drill with superior operating characteristics.

More particularly the present invention is directed to: providing improved automatic reversing means for the spudding mechanism, such that reversal will take place very quickly shortly near the end of the down stroke of the bit, and yet will take place gradually near the end of the up-stroke of the bit.

Still more particularly the present invention is directed to: eliminating all manual control valves from the main circuit; setting up a pilot circuit wholly independent of the main circuit; controlling the pump-to-cylinder circuit by opening and closing a by-pass therefrom, leaving the pump-to-cylinder circuit itself always open; preventing the spudding-sheave from overrunning the spudding-cable,

- and vice versa; and a safety device to reduce the main circuit pressure to substantially zero upon shutting off or failure of pilot pressure.

The present invention consists in the noval parts and in the combination and arrangement thereof, which are defined in the appended claims, and of which one embodiment is exemplified in the accompanying drawing, which is hereinafter particularly described and explained.

Throughout the description, the same reference number is applied to the same member or to similar members.

The single figure shows the hydraulic circuits and associated mechanism of the present invention, largely conventionalized. Other conventional parts of the drill mechanism are not shown, being well known in the art.

From a winch-drum 11 on the main frame (not shown), a cable 12 extends upwardly and over a spudding-sheave 13, journaled in a sheave-block 14, which is slidably mounted at the top of a mast (not shown) in any con- Patented Dec. 23, 1958 venient manner for limited sliding up and down. Thence the cable extends downwardly to support and reciprocate a drill-bit 15, shown in Well-hole 16, which it is digging.

At the foot of the mast (not shown), supported by the main frame (not shown), there is a hydraulic cylinderpiston assembly 17, of which the piston-rod 18 extends up the mast to support and reciprocate sheave-block 14.

Tank 19 is a tank for hydraulic fluid, which supplies, and serves as a sump for, the hydraulic fluid which circulates in the main circuit and the pilot circuit of the present invention.

There will now be described the main hydraulic fluid system.

Main pump 21 is connected on its intake side to the fluid in tank 19 by pipe 20; and on its output side, through pipe 22 and a part of a reversing-valve 23 (hereafter referred to, as the spudding-valve) and pipe 24, to cylinder-piston assembly 17. The control of fluid-flow through the just-described circuit from pump 21 to cylinder 17 is effected not by closing and opening this circuit, but rather by closing and opening a by-pass to sump 19 through valve 23 (as will be described hereinafter).

25 is the pilot-pressure-closed spring-opened plunger of spudding-valve 23. Normally open, it permits the passage of fluid from pipe 22 through opening 26 to resistancevalve 27, and thence through return-pipe 28, back to tank 19. Thus it will be seen that valve 23 takes the place of a conventional reversing-valve, at a gain in simplicity of piping. Either type of valve could be pilot-pressure shifted in both directions, but this would not only complicate the piping, but also would eliminate the following safety feature. In event of shut-oft or break-down of pilot-pressure, spudding-valve 2.3 is opened by its spring,

and the bit will come to rest at the bottom of the stroke. Whereas, without this feature, the bit might come to rest at the top of the stroke; and then upon the resulting stalling of the engine, or the shutting oif of the engine, the bit would drop uncontrolled.

Either type of valve could be pilot-pressure shifted in either direction; but to retain the safety feature, either type of valve would have to be shiftable into its bit raising position by pilot-pressure, and into its bit-lowering position by some means not involving pilot-pressure, such as main-pressure or a spring, the latter being preferable.

Valves 23 and 27 are shown built integral as a single unit. But this is merely for structural convenience; they -could just as well be built separately, and connected by aprpe.

29 is the pilot-pressure-closed main-pressure-opened plunger of resistance-valve 27. When pilot-fluid is no longer supplied to this valve, and spudding-valve 23 is open, seepage of pilot-fluid around plunger 29 and/or through bleeder 55 will reduce to substantially zero the resistance to the by-passing of fluid from pump 21, through pipe 22, valve 23, opening 26, valve 27, and pipe 28, back to tank 19; also to exhausting cylinder 17 through valve 23, etc.

But when spudding-valve 23 is open, and resistancevalve 27 is under the influence of pilot-pressure, plunger 29 of the latter sets up a predetermined back-pressure to this by-passing. The object of this back-pressure is to prevent free fall of sheave 13 during lowering, and thus prevent this sheave from overrunning cable 12. In this connection, resistance-valve 27 can be adjustably regulated by relief-valve 46, in a manner hereinafter described.

Resistance-valve 27 .also cooperates with choke-valve 41, in a manner hereinafter described.

Resistance-valve 27 a.so supplies the following safety feature. in the event the bit is prevented from descending in the down stroke by some external cause (such as sticking in the hole), the back pressure in the main circuit sheave; accordingly, were itnot for 12 would overrun sheave 13 at the top of the stroke.

.pressure when the machine is not spudding. Secondly,

'pilot-pressure-closing establishes a substantially constant resistance to main-fluid flow, regardless of the volume of fluid passing-through the resistance-valve.

3%? is merely a vent-pipe for the upper part -17.

There will now be described the pilot fluid system.

For convenience in studying the figure, the pilot pipes are shown smaller than the main pipes.

31 is the pilot-pump. It is connectedon its intake side to the fluid in tank 19 by pipe 32, and on its output side to start-stop valve 33 by pipe 34. Pipe 35 is the returnpipe from start-stop valve 33 to'tank 19. i

36 is a valve. preferably of a particular typeknown as a sequence-valve (see later herein), connect-ed to valve 33 by pipe 37.

Valve 33 can be any convenient kind of valve, such that when set to stop, it connects pipe 34 to pipe 35; and when set to start, it connects pipe 3 to pipe 37.

38 is a reversing-valve (hereinafter referred to, as the pilot-valve), of any convenient type, connected to sequence-valve 36 by pipe 39. From pilot-valve 33, pipe cylinder at) extends to spring-set pressure-released choke-valve 41,

from which valve pipe 42 extends to the operating end of plunger 25 of spudding-valve 23. For pipe 43, see later herein.

, The operation of choke-valve 41 is as follows. When fluid is flowing therethrough from pipe 49 to pipe 42, the pressure of this fluid on the plunger of this valve will overcome the pressure of the spring to open the valve wide, away from the screw. But when fluid is flowing in the opposite direction, the spring will close the valve (not completely, but rather merely until it contacts the screw) to a narrow bleeder-oriflce, the

size of which is determined by the setting of the screw.

The function of choke-valve 41 is to permit free flow ofpilot fluid to spudding-valve 23, to actuate plunger 25 toclose spudding-valve 23, when rotary member fit) of pilot-valve 38 is in its full-line position; but to bleed back 'fluid through an adjustable orifice from spudding-valve 23, when rotary member 5% is in its dotted-line position, so as to prevent too rapid opening of spudding-valve 23- near the top of the piston stroke. The relatively gradual opening of spudding-valve 23, gradually decreases the pressure in the bottom of cylinder 17, until this pressure is reduced to the pressure-level established by resistancevalve 27, whereupon the resistance-valve takes over. This controlled opening of the spudding-valve also controls the surgeof fluid through opening 36 which might ding-valve 23 opens when sheave 13 and bit 15 are moving upward, the bit at twice the velocity of the choke-valve 4-1, cable Thus resistance-valve 27 and choke-valve 41 perform similar functions: the former, preventing sheave 13 from voverrunning cable 12 during lowering; the two together,

preventing cable 12 from overrunning sheave 13 at the top of the stroke. The need for both expedients is due to the travel-ratio of tools and sheave. This requires that, in

' order to keep cable and sheave in phase, the gravitational pull on the sheave and associated parts must be opposed (so as to reduce thenet effect to one-half or less) during otherwise unbalance the predetermined setting of resisti ance-valve 27. In the spudding cycle of this drill, spud- I 4 both lowering and near the end of raising. This is accomplished during lowering by braking the escape of fluid from the cylinder, and at the top of the stroke by reducing the admission of fluid to the cylinder gradually instead of abruptly.

Pilot-valve 38 is also connected to tank 19 by pipe 43. The fourth port of pilot-valve 38 is plugged, but would be connected by a pipe to the left-hand end of plunger of spudding-valve 23, if that valve were of a sort operated in both directions by pilot-pressure.

Pipe dd extends from sequence-valve to the operating end of plunger 29 of resistance-valve 27. From pipe 44 pipe 45 extends to adjustable relief-valve 46 (which valve serves to regulate resistance-valve 2.7, as will be hereinafter explained), whence pipe 47 connects to tank 1*? in any convenient manner, as via pipe 43.

Pipe 33 is merely a drain-pipe for valve 36. Passage 4% in sequence-valve 36 is to operate-the plunger in this valve whenever pipe 39 is blocked by valv'e38, or otherwise as hereinafter mentioned. It should be noted that pipe 39 is always open to pipe 37, and hence the circuit of these two pipes goes through sequence-valve 36 merely for convenience; it could just as well lay-pass valve 36. The sequence-valve as above described is considered preferable at this place to a conventional adjustable reliefvalve, due to the fact that what is needed at this pointis a relief-valve whose opening is'ccntrolle d by the pressure merely in pipe 37, and is not influenced by the back-pressure in pipe 44.

Also piped lcould extend from the plugged port (no longer plugged) of spudding-valve 38, instead of from sequence-valve 36; in which event the latter would instead discharge into some pipe leading to tank 19.

Reverting now topilot-valvefifi, it will be seen that this valve includes a rotary member 50 which savings back and forth through about 45 degrees, under the influence of trip-dog 51. The two extreme positions of rotary member Sil are shown; one position full, the other position dotted. The fact that trip-dog 51 controls rotary member 56 is indicated by the dot-dash line which connectsthcir respective centers on the drawing.

Trip-fingers 52 (black) and '53 (white) are adjustably secured to-rod 54, which reciprocates with piston-rod 18. Black trip-flnger 52 is in the same plane as the black prong of trip-dog 51. White trip-finger 53 is in the-same plane as the white prongof the trip-dog; but thesetwo planes are different. As. shown in the figure, pistom'rod 18 has just completed its descent, and black trip-finger 52 has recently engagedthe black prong of trip-dogfi l, and thereby has just completed tripping trip-dog'il. into its shown position, thus shifting rotary member 51) of pilot-valve 38 into itsshown full-line position.

The pressures of certain of the valves is important, as will now be explained.

The pilot-fluid pressure acting on plunger 25 of spudding-valve23 must be of such magnitude as to overcome the force of the plunger-spring, and the inertia of the plunger to shift the plunger quickly to its closed position. This pressure is regulated by the'adjustment ofsequencevalve 36. When the pressure in pipes-37 and 35 exceeds the pressure-setting Iof sequence-valve 36, eitherv when plunger 25 has been shifted to its closed position or when pipe 39 is blocked by pilot-valve 33, sequence-valve 36 beyond .this'point to retard the fall of the bit to satisfy 57, certain operating conditions, as is well understood in the art.

The operation of the drill shown and described herein should be readily evident from the figure'an'd the foregoing description, but nevertheless will now be outlined.

Assume everything tobe in the positions shown in the figure.

Both pumps are started.

Pilot fluid circulates unrestricted through pipe 32, pump 31, pipe 34, start-stop valve 33, and pipe 35, back to tank 1?.

Main fluid circulates unrestricted through pipe 20, pump 23, pipe 22, spudding-valve 23, opening 26, resistance-valve 2'7 (which offers substantially no resistance, as there is no pilot-pressure behind its plunger 29), and pipe 28, back to tank 19.

Thus the machine is idling.

Start-stop valve is now thrown to start position, thus shunting pilot-fluid through pipe 37, sequence-valve 36, pipe 3%, pilot-valve 38, pipe 40, choke-valve 41 (which never opposes flow in this direction), and pipe 42, to spudding-valve 23, the plunger 25 of which it shifts abruptly to the left, thus closing this valve. Main fluid, prevented by the closing of the spudding-valve from free return to the tank, proceeds through pipe 24 into cylinder 17 thus raising the piston, and hence sheave 13, and bit 15.

Having performed the closing of spudding-valve 23, the pilot fluid has no-where to go, except through passage 2-9 to shift the plunger of sequence-valve 36 to the left, which it does, thereby permitting itself to'escape through pipe 44, then first closing valve 27 (the position of which, at this-stage of the cycle, is immaterial), and thereafter escaping through pipe 45, relief-valve 46, pipe 47, and pipe 43, back to tank 19.

Shortly before piston-rod 18 reaches the top of its more, white trip-finger 53 engages the white prong of trip-dog $1, rotating this dog, and hence member 50 of pilot-valve 38, approximately 45 degrees clockwise into the position shown dotted, thus connecting pipes 48 and 43 through this valve. Pilot pressure from pump 31 still remains blocked, but now by pilot-valve 38.

There being now no longer any pilot-pressure against the right-hand end of plunger 25 of spudding-valve 23, the spring forces this plunger to the right (but slowly, due to the back-pressure in pipe 42, set up by flow resistance in choke-valve 41). The pilot-fluid'displaced by this shift of the plunger, backs up in pipe 42, and after oozing through choke-valve 41, passes, by way of pipe 40, pilot valve 38, and pipe 3-3, to tank 19.

The opening of spudding-valve23 permits main-pressure from pump 21 to circulate back to tank 19, as it did when the machine was idling, but now not freely, for pilot-pressure in pipe holds plunger 29 of resistancevalve 27 partly closed.

The weight of the bit 15, and of the sheave l3 and associated parts, forces down the piston, and thus forces fluid in gradually increasing volume, out of cylinder 17,

into pipe 24, and into spudding-valve 23, where this fluid reboundsfr'om the bottom of the hole; whereas the rejoins the main pump fluid on its way back totank 19,

through spudding-valve 23, resistance-valve 27, etc.

Shortly before piston-rod 13 reaches the bottom of its stroke, black trip-finger 52 engages the back prong of trip-dog 51, rotating this dog, and hence member of pilot-valve 38, approximately 45 degrees counterclockwise back into its initial position (shown in full lines), thus again connecting pipes 39 and 4% through this valve.

Pilot-pressure, through pipe 49, choke-valve 41 (which does not oppose flow in this direction), and pipe 42, to spudding-valve 23, shifts the plunger 25 abruptly to the left.

This is where we came in.

The above-described cycle is repeated again and again, until stop-start valve is manually closed.

It should be noted that the reversal at the bottom of the stroke is always quick, thus not retarding the working fall of the bit, and assuring a sharp pick-up of the bit as it v versal at the top of the stroke is slow enough to prevent the rising "cable from overrunning the sheave; and that the down-travel of the piston accelerates slowly enough to prevent falling sheave from overrunning the cable.

It should be noted also that a single-acting cylinderpiston is employed, reciprocation being accomplished by opposing the weight of the tools, cable, piston, piston rod, sheave-block, sheave, etc., by automatically alternatingtwo alternative hydraulic pressures in the cylinder; hydraulic pressure overbalancing weight during raising, and weight overbalancing hydraulic pressure during lowering.

The system of the present invention is automatically self-synchro-nizingzi. e., it eliminates the need (which exists in conventional drills of the prior art) of requiring the operator to carefully'control the spudding speed, so as to adapt it to changing conditions in the hole, such (for example) as the extent of bottoming of the bit.

In the claims, except and unless where specifically stated to thecontrary, the mention of a single element performing several functions shall be interpreted as reading on several such elements, and the mention of several similar elements performing functions capable of being performed by a single such element shall be interpreted as reading on a single such element.

Elements shown and described as being built separate or integral, can be builtintegral or separate, except and unless where specifically stated to the contrary.

Although herein the main system and the pilot system are shown and described as independent systems, each with its 'ownpressure-source (i. e., pump), this independence is not to be read into any claim which does not so specify. And even where so specified, this does not exclude the possibility of a common sump and common return conduits thereto.

In the claims the word fluid" is to be understood to include pneumatic fluid as well as hydraulic fluid. In the case of pneumatic fluid the -sump could of course be the atmosphere.

One embodiment of the invention having now been described, it is to be understood that the invention is not to be considered limited to the specific form or arrangement of parts herein shown and described. More specifically, whenever in the specification some improved substitute for a conventional element is shown and described, a limitation to such improved substitute is not to be read into any claim which does not so specify.

What isclaimed is:

1. In an automatically. self-synchronizing spudding mechanism for cable-tool drills, the combination of:

cable-engaging means to impart vertical reciprocating motion to a percussion-drill bit suspended by a cable; a fluid-pressure-actuated single-acting cylinder-piston assembly, acting in opposition to gravity, to reciprocate the cable-engaging means; source means for creating fluid pressure; a sump; a main-fluid system, comprising a first main passage extending from the source means to the cylinder-piston assembly, and a second main passage extending from the first main passage to the sump; a spudding-valve, interposed between the first and second main passages, for alternatively closing and opening the second Y main passage with respect to the first main passage, and

'thereby'respectively causing main fluid to flow alternatively from (1) the source means to the cylinder-piston assembly through the first main passage to actuate the cylinder-piston assembly to raise the bit and (2) from .the cylinder-piston assembly and the source means through the second main passage to the sump to permit gravity to lower the bit; automatic control means for alternatively setting the spudding valve in wear the other of its two alternative positions, responsive to the position and motion of the cable-engaging means, the

first-mentioned setting being effected when the cable-:

engaging means reaches a predetermined bit-lowering position, and the second-mentioned setting being elfectcd when .the cable-engaging means reachesa predetermined bit-raising position; said automatic control means including: a pilot valve, a first pilot passage leading from the source means to the pilot valve, a second pilot passage leading from the pilot valve to the spudding valve to introduce fluid to said spudding valve to actuate the same, a third pilot passage leading from the pilot valve to the sump, said pilot valve being shiftable to two alternative settings to alternatively direct to the spudding-valve through the second pilot passage pilot fluid derived from thesource means through the first pilot passage, or direct to the sump through the third pilot passage pilot fluid exhausted from the spudding-valve through the second pilot passage, said pilot valve blocking in its last-mentioned alternative setting flow of pilot fluid in the first pilot passage and thereby causing therein an increase in pilot fluid pressure, and means responsive to the movement of the cables-.ngaging means to shift the pilot valve; a resistance valve interposed in the main exhaust passage from the cylinder-piston assembly that includes the second main passage, said resistance valve having a restricted passage to resist when partly closed-the exhaust flow of fluid through said main exhaust passage: and being shiftable to open responsive to exhaust pressure in said main exhaust passage; a fourth pilot passage, leading from the first pilot passage to the resistance valve, to introduce fluid to said resistance valve to actuate the same to close; a bypass leading from the fourth pilot passage toward the sump; a relief valve interposed in the bypass and actuable by fluid pressure in the fourth pilot passage to admit fluid therefrom into the bypass and thereby maintain pressure on the resistance valve to actuate the same to close in opposition to the exhaust flow and thereby maintain a predetermined exhaust'pressure in the main exhaust passage; and valve means interposed in the fourth pilot passage for admitting fluid through the fourth pilot passage to the resistance valve whenever the pilot valve is set to block the fluid flow in the first pilot passage and thereby cause an increase in fluid pressure in said passage and in the fourth pilot passage to thereby maintain a retarding fluid pressure on the resistance valve when the cable-engaging means reaches its said predetermined bit-raising position.

2. A spudding mechanism according to claim 1, still further characterized by the fact that the valve means for admitting fluid through the fourth pilot passage comprises: a sequence valve in said passage, said sequencevalveheing actuable by pressure in the first pilot passage ,to admit pilot-fluid from the first pilot passage through saidfsequence valve into the fourth pilot passage.

, 3. A spudding mechanism according to claim 2, further characterized by the fact that the sequence-valve includes means biasing the sequence-valve in opposition to the pressure fluid in the first pilot passage for causing the seguence-valve to open responsive to the degree of pressure in the first pilot passage independent of the degree of pressure in the fourth pilot passage.

4. A spudding mechanism according to claim 1, further characterized by having a choke-valve interposed-in the return passage whichcomprises the second pilot passage, the pilot. control means, and the third pilot passage, saidchoke-valve being adapted to retard the opening of the spudding-valve when the pilot-valve is set topermit the return flow of fluid from the second pilot passage to the third pilot passage, and thereby prevent unbalancing of the resistance-valve by a surge of exhaust fluid through the second main passage.

5 .1111 an automatically self-synchronizing spudding mechanism for cable-tool drills, the combination of: cable-engaging means to impart vertical reciprocating motion to a percussion-drill bit, suspended by a cable; a fluid-pressure-actuated single-acting cylinder-piston assembly to reciprocate the cable-engaging means; fluid pressure source means; a sump; a main fluid passage from the source means to the cylinder-piston assembly, and a second main fluid passage, from the first main fluid passage to the'sump; a spudding valve, interposed between the first and second main fluid passages, for alteruatively closing and opening the second main fluid passage; automatic control means including a shiftable fluidpressure pilot-control means for alternatively setting the spudding valve in one or the other of its two alternative positions, responsive to the position and motion of the cable-engaging means, the first-mentioned setting being effected when the cable-engaging means reaches a predetermined bit-lowering position, and the second-mentioned setting being effected when the cable-engaging means reaches a predetermined bit-raising position, and means responsive to the movement of the cable-engaging means to shift the pilot control means the passage of pressure fluid through said pilot control means being blocked when the cable-engaging means is in its said predetermined bit-raising position; resistance-valve means interposed in the second main fluid passage and having a restricted passage for resisting in varying degrees when partly closed the exhaust flow of fluid therethrough and being shiftable to open responsive to exhaust pressure in said second main fluid passage; a pilot passage connecting said resistance valve to the pilot-control means for introducing fluid to said resistance valve to actuate the same to close; .a bypass leading from the pilot passage toward the sump; a relief valve interposed in the bypass and actuable by fluid pressure in the pilot passage to admit fluid therefrom into the bypass and thereby maintain pressure on the resistance valve to actuate the same to close in opposition to the exhaust flow and thereby maintain a predetermined exhaust pressure in the second main fluid passage; and valve means, interposed in said pilot passage for admitting fluid therethrough to the resistance-valve whenever the means responsive to the movement of the cable-engaging means shifts the pilot control means to block the passage of fluid therethrough when the cable-engagingmeans reaches its said predetermined bit-raising position.

References Cited in the file or" this patent UNITED STATES PATENTS 801,528 Klay Oct. 10, 1905 1,273,618 Julien et al July 23, 1918 2,026,853 Smith Jan. 7, 1936 2,073,809 Salentine Mar. 16, 1937 2,220,271 Peyton et al Nov. 5, 1940 2,282,977 Mast May 12, 1942 2,572,748 Noll et a1 Oct. 23, 1951 2,749,090 Hudson June 5, 1956

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