US2259694A - Diamond drill feed control - Google Patents

Description

H. s. HbFFAR DIAMOND DRILL FEED CONTROL Oct. 21, 1941.

Filed July 12', 19:59

2 Sheets-Sheet 1 Patented Oct. 21, 1941 DIAMOND DRILL rnnnqqnrnop Henry S. Hoffar,

C n da, assienor .t Drills, Ltd, Vancouver Vancouver, British Columbia,

International Multilfieed r.iti, h Columbia Qanada a corporation of British Cdl iimlfia Application July 12, 1939, Serial No. 284 ,0 67 6 Claims. (01. 255-4 My invention relates to devices for drilling rock. The invention is best illustrated in conjnnction with a diamonddrilL-but certain principles thereof, as will appear hereafter, may be applied also to percussion rock drills. The invention is concerned primarily with the feed arrangements for such drills, having in mind the conditions under which they are intended to operate. 7

It is considered preferable, in the operation of certain diamond drills, to employ high speed rotation, and rather light pressure to advance the drill red, sincetherebythe life of the diamond points can be materially increased. However, it is desirable to advance the drill as rapidly asitis capable, without undue wear, of cutting through the rock, but the rate'o-f feed is-a variablequantity; and depends upon the resistance encountered, which in turn depends upon the-rock formation with which the point isengaged, and, as such factors vary from time to time, arate of advance which'would' be 'permissibleundersome conditions might be unduly rapid and destructive of the drill point if persisted in under other conditions. It has not been considered practicable to provide an automatic feed, either-hydraulic, pneumatic or mechanical, which would be wholly self-adjusting to the 'dif ferent conditions encountered from time to time, to accomplishadvance of the drill at whatever rate best'suited to the conditions momentarily jenconntered, and changing from' moment to moment, yet Ihave discovered'how this'may be done, and it is an object of the present invention to provide feed arrangements and controls to accomplish the above end. *It is also desirable to provide means, when employing a pressure fluid as the primary means {to-accomplish advancejto accomplish manual feed when desirable, and to provide further means whereby, should the drill point pass into 'a fissure or r'ock'chamber, it will not advance suddenly under theapplied pressure across the fissure and strike the opposite wall, for such impact is'extremely destructive of the' diamond peints. Such occurrences are infrequent, yet it is' desirable to provide means, if that can be done without-undue complications, whereby, in a drill employing a pressure fluid as the primary advancing means, restraint can be imposed upon the advance to prevent such unrestrained plunging; forward when the resistance is wholly removed. v @It 'is also desirable to provide feed means or feed controlling means, especially for use where 55 ftion" npona mine bar,

the advance is primarily accomplished under the influence 0f a. pressiire fluid, whereby the permitted maximum rate of*advance Inay'be variedjat willto' suit diiierent" operating conditions," yet"'without increasing the pressure at the drill point, and it is' an object" ofthe present invention to provide control means adjustable as @1 9 Diamond drills, particularly such as are portare: th is a' b iq :beine f b rte f m pint to point andfsuppoifted'in operative posi-r a ,r i have-m w n i de a pressure-cylinder and a piston movablejtherewe a amni na a e of "th an a the ri red *b' fi iEihfi iw t dih pennation of the-piston or extending through fitf, in 1 1 mann t a i F r Q th r ll' edi enthe0 tei of ww e stati ns it as one saw" t h v vai ab e" a 9 w tra e are; manly twice the -al len th fa ithe il o v t ieeaj l n i i Whe 'ope atinisli crampe Quarte s. a in a m e drift or tunnel, working space is limited; and it a nece sary und uch. cond tions to sho t n the length githe drillitself to about half the available. s hereby necessitatin frequent sto age p ck feed citric piston, and 'for to 'nj"t1on. 0f additional lengths to the can ,m i. hidtdid consume timabut it r e-I- we?" a i sap n re deeam it ate r yid fi i" me hanism or such g ve a ee h o advancee ual es aetn ivtheentir c ear s ace available, tqt e end, i stoppa es may the le frequent 39 secti n mbee pneat and it an object ,Qft enr se r l. tenti nxto provide feed machae orl iesjhavingi the. capabilities and advan a es indicated, and which is also'suited to the; other necessary-conditions which it -encountersin use, V

Q .It isaiurtherohject to. provide feed mechanism pf :the .sort indicated, incorporating a cylinder tand alslide esters-any thereof, connected to the piston within by a casement over sheaves cat opposite ends of" the cylinder, which slide supports; a rota-tive motor in the case of a diamond drill, or a rtativeor reciprocativeper- .eussion device' in the case of a rock drilh' which device; in either'instance, is so mounted that it may beswung aside out off the {line of the drill rod, so that, for instance in a" diamond drill, additional sectionsmayfbe coupled on, or the e r ama emlia t i still a-iurtherobject is the improvement in order to accomplish feed Figure l is a perspective view, with parts carried by the mine bar, the head [1 being permanently secured to the exterior of the cylinder, as by welding. By reason of the projection of the head I! the slide 3 may not be completely circular, but is saddle shaped, as is best seen in Figure 4. To prevent its rotation around the cylinder a key 31, received in a groove in the exterior of the cylinder, is received likewise in a corresponding groove in the slide 3.

Carried by the slide 3, but preferably indirectly through interposed means, which will be described, is a coupling broken away, illustrating a diamond drill, the

feed mechanism of which isIinop'erative position with relation to the mine b'ar and to'the drill rod, but in which the rotative motor and coupling to the drill rod have been swung aside for access to the drill rod.

Figure 2 is a longitudinal feed mechanism, of Figure 3, the parts being rearranged somewhat from the showingin Figure 1 for com venience ofillustration. v b I 1 Figure 3 is a part elevation and; part section, taken onthe line 3- 3 of Figure 2, and Figure 4 a transverse section substantially'on the line 4 4 of Figure 3. H I A pressure fluid is still employed as the primary forcing or advancingmeans and hence within a cylinder I, closedby theendslll and H, islslidable a packed piston 2. The cylinder heads!!! and II are hel'dupon the ends of the cylinder l to close it, preferably bytension means extending through the cylinder and the piston, as shown at [2 and I3. In effect these are tension-rods, and the member I2 isan actualrod anchored at the two ends. The member I3 is a hollow'rod, howeverphaving an aperture l4 atone end', within the'cylinder, the rod extending through the head II at this vend and provided 'with a cap l5ft'o closethis end, so that fluid entering fat 'the' opposite end, adjacent the head ID, will be. admitted'into the cylinder through the aperture l4. w The cylinder is made of approximately the len'gtho'f the clear space; and while certain devices, applied externally, reduce the length of the cylinder somewhatyit isof' a length considerably more than" half the expected "feed distance; and

section through such I substantially on the "line 2-2- affords an extent-ofadvance considerably more than half the clear distance. To this endyinstead of a rigidpiston rod projecting from the piston 2-, a flexible cable- 22 is-anchored at 20 in the piston, extends throughsuitable packing glands 2 I atthe cylinder heads, and thence over sheaves 23 supported externally uponeach cylinder headn Being. thusr'eversed-in direction, externally ofthe cylinder, the cable 22-extends to a slide 3 mounted upon andguided for movement lengthwise of. the cylinder l, to which slide the cable 22 is anchored, as indicated-at 24. A suitable guard 25 may surround the.sheaves 23. By suchan expedientthe piston 2.may move substantially the full length of .thecylinder i, being stopped in this instance by the glands 2| or by suitablestops at about this point, or by stops engaging the slide .3, w hich is connected .to the drill rod D. The slide 3 may have a length of travelequalto the travel of the piston within the cylinder, and yet the cylinder may .be made of a length almost equal ,to the full extent of clear space in the drift.

The cylinder l is normally mounted for swiveling upon a mine barlvlby means ofa swive head Hreceived in a similarly shaped socket 5 which is adapted to fit within the end of the drill D. Since the coupling 5. is mounted upon the slide 3 it partakes of the latterslengthwise movement. The coupling 5, especially in the case of a diamond drill, is likewise rotative about the axis of the drill rod, rotation being accomplished in such a case by a rotative motor 4. The form of this motor is largely immaterial. As shown herein it is a rotary motor intended for operation by compressed air and its form and arrangementis of importance to the remainder of the invention only in that it is somewhatunbalanced dynamically, and thereby tends to produce vibration. Being directly coupled to the drill rod, it is intended for rotation at the rate of rotation best suited for operation of the drill.

This motor 4, being in alignment with the drill during normal drilling, is preferably so mounted that it may be swung aside when it is desired to engage the drill rod to withdraw it, or when it is de'siredto coupleon a further length of drill rod. Accordingly the motor 4 is mounted pivotally or swingably upon theslide 3 at 43, and is normally held to the slide, against swinging, by a swingably mounted bolt 42 receivable within a fork34 of the slide 3. In Figure 4 the motor is shown in operative position, and in Figureil it is'shown swung'aside. Hose connections for supply of pressure fluid or for water supply have been omitted from the drawings, but would be flexible to permit such swinging. InFigurel there is-shown the control valve 4| for regulating the supply of the pressure fluid for rotating the motor 4. The motors shaft 40 is in alignment with the drill rod D and one end of its shaft carries the coupling 5 when in the position of partsshown in Figurel.

' It is convenient to note at this point thata pressure fluid, whether air or water or oil, is supplied to the interiorof the cylinder I, at one side or theiother of the piston 2, through the head Ill. The fluid is supplied by a connection at L60 'past' a metering valve 6!, and past a four-way valve 6, controlled by the handle 62,-by means of which the pressurefluid may enter directly through the head H], by way of the connection at 63, or by way of a connection filto the end of the hollow rod l3, -previously mentioned, and by means of which the -pressurefluid is admittedito'the" distant face of the piston. A pressure limiting or reducing valvemayalso be eniployed at this point, if desired or required. a The feed mechanism thus far described is op erativewithout more to efiect feed, under the influence of thepressure-fluid acting upon the piston 2, and to eifect drilling under theinfluence of rotationeifected by rotation of the motor 4. However, there are times when it is desired to enploy hand feed, or to control manuallyv the rate; or extent of feed, and Ihave therefore prolvided a manual feed screw, and in so'doing I have discovered that such a feed screw, when employed in-conjunctionwith the pressure fluid .cnt,"s'er've also to control the rate of advance automatically without. the interposition of any 'nianual means or control, precisely in accordance with the extent of resistance encountered. The feed screw 1 is journaled by combined rotativeand thrust bearings in the opposite heads, of the cylinder. The saddle or slide 3 is provided with a trough through'which the feed screw 7 passes; but with which it has no threaded engagement. This trough merely serves to position it, and to backit up when the feed screw is engaged by a half nut II. This half nut H is guided in a frame 31 upon the slide 3, and its position is controlled by a screw 12 connected through a swivel with the nut II, and provided with a handle 13 whereby the screw 12 may be rotated. By backing 01f the nut H the feed screw 1 may be left wholly free of the slide 3, and consequently of the piston 2, and under such conditionsthe feed is" accomplished wholly by means of and under control of the pressure fluid. If the opposite ends of the cylinder are vented to remove artificial resistance of the fluid to advance, feed may be accomplished wholly under manual control through the feed screw 1, and by means of an operating or turning arm 15 secufable upon an end of the screw 7.

However, when operating under the influence of the pressure fluid, I have discovered that if the nut H be left in engagement with the screw 1, control of the advance may be accomplished with little effort, and manually, by turning the handle 15, and indeed may be accomplished v wholly automatically, the handle turning to permit advance, but only at a rate which is a function of the length of the arm and the mass of the handle 15, which constitutes an unbalanced weight afiecting the periodicity or amplitude of the vibrations generated by the motor 4, the vibration also being affected somewhat by the resistance of the rock encountered by the drill point.

It is not entirely clear to me just why this action occurs. It has been discovered by me in practice, and I have discovered how the same may be controlled and regulated, but the operation is substantially the same no matter in what direction the drill point is operating, whether down, up, or laterally. The action is always to feed the drill point forwardly by automatic rotation of the feed screw 1 in the proper direction, but only at a rate which is consistent with the resistance encountered by the drill point. If the resistance increases, the speed of rotation of the drill point and of the motor 4 is reduced, thereby reducing the rate or periodicity of vibration of the entire assembly, and in consequence decreasing the rate of rotation of the feed screw 7, and thereby the rate of advance. The rate of advance is thus automatically compensated and made to correspond to the resistance encountered, and a diamond drill, thus equipped, in operation, operates by repeated surges as the drill speeds up and then meets increasing resistance and slows down, and then speeds up again. The variation in speed is not appreciable, but sufficient to be noticed.

In attempting to explain this action it appears to me that the pressure of the pressure fluid against the piston reacts through the cable 22, the slide 3, and the nut 1| upon the screw 1, tending to create friction to hold the screw against rotation, though, by pressure, tending to slide the nut along the incline of the screw thread, and thus to induce rotation of the screw. However, the whole assembly; is set into vibra tion' by the rotation of the motorl as it isaffected by the dynamically unbalanced handle '15. This effects momentary release of the nut from the feed screw, because there is necessarily working clearance between the two, and since the fluid pressure on piston 2 presses the nut along the screw, it'tends to rotate, its thread sliding down the thread of the nut H. Rotation in the proper direction is assured because the follow-up of the piston pressure prevents reverse rotation, and tends to" slide the nut down the screw thread, inducing the screws'rotation in the proper direction. The extent to which it may feed is thus dependent upon the. periodicity and amplitude of the vibration, since change in its periodicity affects the number of releases and reengagements between the nut and screw, and the amplitude affects the severity of the shock between them, upon each engagement. I have found that variation of the length of the arm of handle 75 upon the screw influences the rate of advance by itsaifect on the vibration, with a given screw pitch. Consequently in order that the rate of advance may be controllable, the handle 75 is'slidably received in the head 16 secured upon the squaredend ll of the feed screw 'I.- The handle is held in arl'yadjusted position, transversely of the axis of the screw, by such means as the s'et screw i8. By adjusting the handle 15 outwardly the rateof feed is increased, and vice versa.

Whatever may be the true explanation, the device has been found to operate thus in practice, and there is provided by such means an extremely desirable and eificient regulation of the rate of advance by adjustment of the length of the handle arm, and automatically within the range corresponding to the handle setting in accordance with momentary changes in resistance encountered by the drill rod, to the end that the drill may continue to rotate at maximum speed and rate of advance, and yet be automatically protected from too great advancing pressure, or from too high speed consonant with the pressure actually applied.

What I claim as my invention is:

1. A diamond drill or the like comprising a coupling for connection to the drill rod, a slide carrying said coupling, a closed cylinder disposed parallel to the drill rod and constituting a parallel guide for said slide, a piston slidable lengthwise within the cylinder, means to supply a pressure fluid within the cylinder to accomplish such movement of the piston, a sheave at each end of the cylinder, a cable, suitably packed at the cylinder heads, anchored to the piston and to the slide, and extending over the sheaves, to transmit lengthwise movement of the piston to the slide, coupling, and drill rod, a screw and nut extending parallel to the cylinder, and operatively connecting the cylinder and the slide, and means efiecting vibration of the assembly during fluid feed, thereby to regulate the feed rate automatically through the screw and nut.

2. A diamond drill or the like comprising a slide and a coupling carried thereby for connection to the drill rod, a cylinder and a piston slidable lengthwise thereof, and operatively connected to the slide to advance the coupling and the drill rod, means to supply a pressure fluid within the cylinder to eiTect such advance, a screw journaled upon and extending parallel to the cylinder, a nut engaged with the screw and carried by the slide, an arm projecting radially from the screw, and means efiecting vibration of the assembly during fluid feed, thereby to regulate the feed rate along the screw, in accordance with the character of the vibration governed by the effective length of said arm.

3. A diamond drill or the like comprising a coupling for connection to the drill rod, a closed cylinder and a piston slidable lengthwise thereof, a slide carried by and guided upon the cylinder for lengthwise movement, a rotative motor carried by the slide and operatively connected to the coupling, an operative connection between and the slide, including a cable aneach and guided at the ends of the pressure fluid within the piston chored ,to cylinder, means to supply a the cylinder to effect advance of the piston, and reverse feed of the slide and coupling, a feed screw parallel to and journaled upon the cylinder, an arm projecting laterally therefrom, and a nut carried by the slide, and engageable with the screw, vibration of the assembly upon rotation of the motor, permitting advance of the slide and coupling at a rate dependent upon the resistance encountered and the degree of lateral projection of said arm from the screw.

4. The combination of claim 3, including means operable at will to retract the nut from engagement with the screw.

5. A diamond drill comprising a cylinder and a piston movable lengthwise therein, heads closed upon the cylinder sure fluid feed means of the cylinder, a slide guidfor movement lengthwise thereof, means, including a cable anchoredto each of the piston and. slide, and runningover guides at eachend of the cylinder, for moving the ,slide equally and oppositely by movement of the piston, a couplingior connection to the drill rod, carried by said slide, means extending through the piston and cylinder, and holding the ing the opposite ends heads upon the cylinder, said latter means including a hollow, rod connected at one end. to a. pressure fluid source, and opening within the cylinder beyond the piston, for supply of pressure fluid for advance of the piston and slide, and valve means to control the supply of pressure fluid through said hollow rod. 7 6. In a rock drill, the combination of a support, a drilling and drill-engaging means, a presto advance the drill-engaging means, a feed screw and nut operatively connected between the support and the drill-engaging means, and subject to pressure of the fluid feed means, vibratory means, a mass carried by the screw eccentrically thereof, and means to adjust the degree of eccentricity of the mass, thereby to regulate the vibration of said vibratory means which in turn influences the rate of relative rotation of said feed screw and nut, and consequently regulating the rate of advance of said drill-engaging means governed by such relative feed screw and nut rotation.

HENRY s. HOFFAR.

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