US3409089A

US3409089A - Feed control means for rock drills

Info

Publication number: US3409089A
Application number: US540437A
Authority: US
Inventors: Meyer Waldemar
Original assignee: Atlas Copco AB
Current assignee: Atlas Copco AB
Priority date: 1966-03-02
Filing date: 1966-03-02
Publication date: 1968-11-05
Anticipated expiration: 1985-11-05
Also published as: SE339202B; GB1107640A; DE1533642B1; CH465535A; AT294727B; NO119631B

Description

Nov. 5, 1968 w. MEYER 3,409,089

FEED CONTROL MEANS FOR ROCK DRILLS Filed March 2. 1965 4 SheeCS-23h96?l l Fig.; l o 30 5 4 4 INVENTOR. Waldeman meyer'. BYW NMa-91 Y' u mamy NOV. 5, 1968 W` MEYER 3,409,089

FEED CONTROL MEANS FOR ROCK DRILLS Filed March 2. 1966 4 Sheets-Sheet 2 2 70 79 ja 79\ 75 H/ 75 42.

63 6455 .7g/ l 8l 64 5 87 i 9/ 700 553 59 'f EN 90 65 i; 1 46 67 66 89 60 F/g. 6 6l 58 l 798076 O3l 7879 64 73. 87 r 1 1 90 T T 9/ INVENTOR. Wadcmnx. mage@ BYqwK hu uw W.l MEYER 3,409,089

FEED CONTROL MEANS FOR ROCK DRILLS Nov. 5, 1968 Filed March 2, 1966 4 Sheets-Sheet 3 ll l [/34/ 5 ll I NVEN TOR.

'cfg-8 L39 [38 38 WaMemaR. meyb BY qmmnnicmqn.

his nome* NOV. 5, 1968 W, MEYER l 3,409,089

FEED CONTROL MEANS FOR ROCK DRILLS Filed March 2, 1966 4 Sheets-Sheet 4 5 /65 /66 785 /6/ f2 f /67 Fig/o 0` O 17;

7 I .34 f N a I /95 164 O 58 /63 f2 76 7a /7/ Fig. ll

INVENTOR. Woldemcm magen h3: ahum);

United States Patent Glce 3,409,089 A Patented Nov. 5, 1968 3,409,089 FEED CONTROL MEANS FOR ROCK DRILLS Waldemar Meyer, Stockholm, Sweden, assignor to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed Mar. 2, 1966, Ser. No. 540,437 Claims. (Cl. 173-9) ABSTRACT OF THE DISCLOSURE Feed control apparatus for rock drills and associated feeding apparatus is provided which is disposed between the rock drill and the feed motor therefor which senses directly any above-normal torque in the rotation mechanism for the drill steel caused by the steel becoming struck for instantaneously actuating the feeding action of the feed motor to stop the feeding action momentarily or to reverse it depending upon the extent and time the abovenormal torque is applied to the steel. In addition, the control apparatus has the reversing valve thereof disposed on the supporting frame for the rock drill and associated slide adjacent the feed motor so that the valve is not subject to the impacts of the drill apparatus itself and so that the feeding motor responds immediately to movements of the valve. Further, the actual torque sensing control is disposed adjacent the rifle bar of the rotation mechanism for limiting the load on the ratchet and pawl devices therefor for prolonging the life thereof.

This invention relates to feed control means for rock drills and is concerned with the problem of avoiding sticking of drill steels when drilling in fissured or faulty rock. The suppression of sticking disturbances is particularly important in connection with operation of groups of automatic drills on drill wagons or jumbos on which one operator has to handle three or four rock drills at a time. Too much time is often lost when a drill sticks for restoring normal running thereof and the operation program of the other drills is delayed accordingly. It is therefore the main object of the invention to provide a feed control means for rock drills capable of automatically avoiding sticking of the drill steel. A further object of the invention is to provide a feed control means which is capable of responding to torque developed by the rotating means of the rock drill in a manner to reduce the feeding force when an excessive torque occurs in the rotating means. A still further object of the invention is to provide a feed control means for rock drills capable of momentarily retracting the drill upon the development of excessive torque in the rotating means of the drill and of restoring forward feed of the drill immediately upon said torque becoming normal.

The above and other objects of the invention will become obvious from the following description and from the accompanying drawings in which some preferred embodiments of the invention are illustrated by way of example. It should be understood that these embodiments are only illustrative of the invention and various modifications may `be made within the scope of the claims.

In the drawings, FIG. 1 is a partly sectional longitudinal view of a rock drill incorporating the present feed control means. FIG. 2 is an enlarged transverse sectional view on the line 2-2 in FIG. l. FIG. 3 is an enlarged transverse sectional view on the line 3--3 in FIG. 1. FIG. 4 is an enlarged transverse sectional view on the line 4-4 in FIG. 1. FIG. 5 is an enlarged longitudinal sectional view substantially on the line 5-5 in FIG. 1 showing a control valve and actuating means therefor as incorporated in the present feed control means. FIG. 6 shows the parts in FIG. 5 disposed in another operating position.

FIG. 7 is a transverse sectional view illustrating another embodiment of the feed control means. FIG. 8 is a fragmental longitudinal partly sectional view 0f a third embodiment of the feed control means. FIG. 9 is a side view on the line 9-9 in FIG. 8. FIG. vl0 is a longitudinal sectional view of the rear portion of a rock drill incorporating a still further embodiment of the feed cont-rol means. FIG. 1l is a transverse sectional view on the line 11-11 in FIG. 10.. FIG. 12 is a transverse sectional view on the line 12-12 in'FIG. 10. FIG. 13 finally is a diagrammatic side view illustrating av still further embodiment of the feed control means. l l

In FIGS. 144 the rock drill 20 is provided with a hammer piston 21 recoprocable in a cylinder bore 22 under the action of pressure fluid. The pressure fluid is supplied by a hose to a nipple 24 communicating via a throttle valve, not shown, with a chamber 25 at the rear end of the rock drill 20. A distributing valve 26 and suitable passages, not shown in detail, are provided for distributing the pressure fluid from the chamber 25 to the opposite ends of the bore 22 in a manner to reciprocate the hammer piston 21 therein.

During its reciprocation the hammer piston 21 delivers impact blows to the shank of a drill steel 27 which is slidably but nonrotatably received in a drill chuck 28 in its turn rotatably mounted at the forward end of the rock drill 20. The shank of the hammer piston 21 is ribbed and the ribs thereof are in axially slidable but nonrotatable engagement with the splined inner end of the chuck 28. In an axial bore provided in the hammer piston 21 there is aixed a rifle nut 29 which slidably engages the spiral flutes of a rifle bar 30 rotatably journalled in the rear portion of the rock drill 20 and projecting forwardly into the axial bore of the hammer piston 21. The rifle bar 30 is connected at the rear end thereof to a ratchet and pawl means. In the embodiment depicted in FIGS. 1-4 this ratchet and pawl means consists of a pair of pawls 31 pivotally mounted on a head 32 forming the rear end portion of the rifle ybar 30. Circumferentially around the head 32 there is provided a ratchet ring member 33 cooperating with the ratchet pawls 31 which by springs, depicted at 23, FIG. 7, are urged from the head 32 radially outwardly to engage the ratchet ring member 33. As obvious, the rie bar 30 is restrained hereby against rotation in one direction, for example ,clockwise direction when viewed in FIG. 4, but is free to rotate in the opposite counter-clockwise direction.

A water hose 34 is connected to the rear end of the rock drill 20 and conducts water to a flushing tube 35 extending axially through the rifle bar 30 and hammer piston 21 into a through axial flushing passage, not shown, in the shank of drill steel 27.

The entire rock drill 20 is pivotally mounted about its longitudinal axis, i.e., the axis of the drill steel 27, on

bearings

36, 37 carried on a slide 38. To this end the front bearing 36 supports a cylindrical surface 39 around the chuck portion of the rock drill 20 and the rear bearing 37 provides a support for a bushing 40 on the backhead of the rock drill 20. Through the bushing 40 water is conducted to the flushing tube 35 from the water hose 34.

The slide 38 has opposed guideways 44 thereon whereby it is slidable along an elongated guide frame 45 having guide flanges 46 for cooperation with the gudeways 44. The guide frame 45 carries a pressure fluid driven feed motor 48 which may be a rotary vane motor as exemplified in FIGS. 1, 5 and 6, a piston motor or may be of other type. The feed motor 48 is in driving engagement with a chain 49 extending over :chain wheels 50, FIG. 3, at the opposite ends of the guide frame 45 to a connecting block 51 centrally at the underside of lthe slide 38 to which the chain 49 is affixed. By rotating the motor 48 in Y i 3 forward or counter-clockwise directiomas viewed in FIG. 1, the slide 38 and the rock drill 20 are moved in forward direction to the left in FIGnl for applying a feeding force on the drill steel 27. Reverse or clockwise rotation of the motor 48 in FIG. 1 moves the rock drill 20 away from the rock face to the right in FIG. 1.

The rock drill is prevented from rotation in its

bearings

36, 37 in a direction opposite to the locking direction of the ratchet and pawl means of the rock drill 20 by a lug 54 thereon projecting radially outwardly from the rear end of the rock drill 20 and contacting an abut- -ment 53 on the slide 38. This contact is maintained by elastic means such as a spring 55 interposed between the lug 54 and a spindle 56 which is in threaded axially adjustable engagement with an ear 57 provided on the slide 38.at one side thereof opposite to the lug 53. It should be observed that the force of the spring 55 tends to -resist pivotalmovement of the lug 54 in the locking direction of the ratchet and pawl means. Such resistance,` however, may be overcome by excessive loads on the ratchet and pawl means causing angular displacement of the entire rock drill 20 and lug 54 in the

bearings

36, 37 away from the abutment 53. The angular displacement also causes movement of a spherical actuation knob 59 aixed to the rear end of the rock drill 20 and cooperating with a plunger 60 having a sliding tight fit in a hydraulic master cylinder 61. A conduit 58 connects the interior of cylinder 61 with a slave cylinder 62 in which a servoplunger 63, FIG. 5, is slidable. Thanks to the hydraulic interconnection by conduit 58, the servoplunger 63 obviously will move and react in synchronism with the actuating plunger 60 to angular movements of the rock drill 20.

An accumulator 64, FIG. 5, communicates via a conduit 65 with the conduit 58 and the

cylinders

61, 62 for feeding compensating additional fluid thereto and for maintaining a suitable pressure therein. To this end the accumulator includes a housing divided by a diaphragm 66 in a liquid chamber 67 and a pressure fluid chamber 68. The pressure uid chamber 68 is connected by a conduit 69 to the pressure uid source, not shown, and pressun'zation of chamber 68 causes compression of the liquid in chamber 67. Fluid and pressure is thus transmitted from chamber 67 via la spring-pressed check valve 700 to conduit 65 and on to the

cylinders

61, 62.

A control valve 70 is affixed to the guide frame 45 for automatic control of the rotational direction of the feed motor 48. The control valve 70 includes a housing 71 which by means of a hose 72 is connected to the pressure fluid source. Pressure fluid is conducted centrally into the housing 71 to the inner ends 0f coaxial valve seats 73, 74 provided at the bottom of opposed

internal chambers

80, 81 in the housing 71. The

seats

73, 74 are adapted for cooperation with a pair of opposed

reduction valve members

41, 42 respectively, mounted in coaxial fittings 75 threaded to the housing 70 and projecting from opposite directions into the

chambers

80, 81. The fittings 75 are provided with outer radial exhaust openings 76. The

reduction valve members

41, 42 each include a plunger 77 slidable in fitting 75 and a ball valve 78-displaceable to seat on the

corresponding seat

73 or 74 as well as lan intermediary spring 79 between each of said ball valves 78 and plungers 77 and compressible by movement of the plunger 77 against ball valve 78 when the latter is seated. When the ball valve 78 is seated and the spring 79 is fully compressed, an axial passage 82 provided in each of the plungers 77 connects the corresponding internal chamber 80` or 81 to the atmosphere via the adjacent exhaust opening 76.

A yoke 84 is connected at one end thereof to the plunger 77 of valve member 41 and a spring 85 is disposed between the tting 75 of valve member 41 and the yoke 84 for purposes of moving the ball 78 of valve member 41 away from its seat 73. The opposite end of the yoke 84 is connected to servoplunger 63, while an adjusting screw 86 is connected to the plunger 77 of valve member 42.

. 4. By adjustment of the .screw 86 the distance between the two plungers 77 can be adjusted as desired and both ball valves 78 can be brought down on the

seats

73, 74 under suitable precompression of springs 79.

The internal chamber V80 in the housing 71 is connected by means of a conduit 87 to the feed motor 48 for sup'plying pressure fluid to one side of the vane rotortherein while the other internal chamber 81 in` a corresponding manner is lconnected by a conduit 88 to the opposite side of the feed motor rotor. In an intermediate plane between the points of connection of the

conduits

87, 88 the feed motor 48 has Ia main exhaust opening 89.

The servoplunger 63 is `directly connected to the yoke 84 and the spring 85 acting between the fitting 75 of valve housing 71 and the yoke 84 tends to move the servoplunger 63 to its deepest position in the slave cylinder 62 as'idepicted in FIG. 5 and corresponding to the position of the rock drill 20 with the lug 54 thereon in abutting contact with abutment 53, FIG. 4. In such position the yoke 84 via the screw 86 keeps the plunger 77 of the reduction valve member 42 depressed and the ball valve 78 in a closed position on its seat 74 under compression of the intermediate spring 79.

In operation pressure uid is supplied via a hose to the nipple 24, the chamber 25 and the distributing valve 26 to reciprocate the hammer piston 21. The spiral utes on the rie bar 30 chosen as example in FIG. 1 have a pitch tending to -rotate the rifle bar in clockwise direction during return of the hammer piston 21 and in counter-clockwise direction during its working stroke when it beats against the drill steel 27. Since the ratchet and pawl means, FIG. 4, prevent rotation of the rifle bar 30 in clockwise direction, the hammer piston 21 obviously will be rotated in counter-clockwise direction during the return stroke and in such rotation the drill `chuck 28 and the drill steel 27 will take part as long as the resistance to rotation is small. With the hammer piston and the rotating means thus in operation, pressure iluid is also supplied to conduit 72 of the control valve 70, FIG. 5. Since valve seat 74 is kept closed by valve member 42, pressure fluid will be conducted via valve seat 73 to the internal chamber 80 and on to the conduit 87 to rotate the feed motor 48 in forward or counter-clockwise direction, FIGS. l and 5. The pressure fluid will be exhausted via the main exhaust opening 89 and a portion thereof will also be ventilated by the vanes of the feed motor via the conduit 88 on to the internal chamber 81 in the valve housing 71 and thence via the exhaust pass-age 82 in valve member 42 to the atmosphere via the exhaust opening 76. The forward rotation of the feed motor 48 causes forward movement of the rock drill along the guide frame 45 and drilling is commenced.

If now the drill steel 27 by some reason is stuck in the rock or tends to stick therein, the drill chuck will be slowed down or stopped in its rotation. During the return stroke of the hammer piston 21 thc pressure uidacting against the piston will thus tend to release its energy by forcing the rie bar to rotate in the locking direction of the ratchet and pawl means, i.e., in clockwise direction when viewed in FIG. 4, and the torque load on the ratchet ring member 33 and thus on the rock drill 20 is sharply increased. By suitable setting of the spindle 56, the elastic means or spring 55 can be set to yield when the torque load reaches or exceeds a predetermined value, at which instant the entire rock drill 20 will be turned by the ratchet and pawl means in clockwise direction in FIG. 4. Such turning causes spherical knob 59 to compress the master plunger 60 and causes the slave plunger 62 to move the yoke `84 towards or to the position depicted in FIG. 6. In this position the plunger 77 has moved the ball valve 78 of valve member 41 against its seat 73 and has compressed the intermediate spring 79 thereof to keep the seat 73 closed by ball valve 78. Simultaneously herewith valve member 42 has moved away from seat 74 and has relieved its ball valve 78 from spring pressure. Pressure Agalgos@ Huid delivered by the conduit 72 now llows via the relieved valve seat 74 on to the internal chamber 81 and to the conduit 88 to rotate the feed motor 48 in, reverse direction, i.e., clockwise direction in FIGS. 6 and 1. As` a result thereof the slide 38 is moved away from the rock face reducing thefeeding force applied on the drill steel and allowing free rotation of the drill chuck 28. This causes immediate torque relief or reduction at the ratchet and pawl means so that spring 55 can return the lug 54 against the abutment 53 and the rock drill 20 to its position shown in FIG. 4. The spherical knob 59 thus releases the master plunger 60 and the spring A85 of the yoke 84 thereupon moves the plunger 63 back to depressed position in the slave'cylinder 62 which also raises the master plunger 60 back to its starting position depicted in FIG. 5. Simultaneously with the return movement of the yoke 84, the

reduction valve members

41, 42 return totheir position shown in FIG. 5. Consequently the rock drill is again moved by the feed motor 48 towards the rock and the drilling is continued until the drill steel again is stuck or tends to stick.

If the sticking tendency is only moderate, it can often be overcome without reversing the rotation of the feed motor 48. To this end the balls 78 of both

valve members

41, 42 will be adjusted by screw 86 to close seats 73,'74 under a certain compression of both springs 79 when the plungers 77 are at equal distance from their corresponding

seats

73, 74. In such case the movement of the yoke 84 will stop without opening of the opposed valve seat 74 taking place, only causing seating of the ball valve 78 of valve member 41 on seat 73 and some compression of the intermediate spring 79 of valve member 41. Such spring compression reduces the pressure in chamber 80 and conduit y87 below the live pressure in conduit 72 and the reduced pressure in conduit 87 will slow down the feeding movement of feed motor 48 so that 'the drill steel 27 can be hit free of the obstructions by the hammer piston 21. Thereupon the control valve parts Will return to a position corresponding to FIG. 5.

Between the

conduits

87, 88 there is `provided a manually actuated reversing valve 90 which may be operated by a lever 91 or may be remotely controlled. The valve 90 is used for controlling forward or rearward movement of rock drill at will.

In the embodiment according to FIG. 7 the rock drill 20 is fixedly connected to the slide 38 as by bolts and the ratchet ring member 33 is mounted pivotally in the rock drill 20. In other respectsthe construction of the rock drill is identical with the embodiment shown in FIGS. 1-4 and is therefore not illustrated again in detail. The ratchet ring member 33 has an arm 100' connected thereto which projects outwardly'in radial direction from the ring 33 through a slot 101 in the housing of the`rock `drill12'0'. Aplunger 102 is in engagement with the arm 100 and tends to move it in counter-clockwise direction when viewed in FIG. 7 to the upper end of the slot 101 due to the action of pressure fluid and a spring 105 against the inner face of the plunger 102. The pressure fluidfpreferably compressed air, is su-pplied from a source, not shown, through a conduit 103 to a cylinder 104 affixed to the slide 38 and slidably receiving the plunger 102 and the spring 105. The -plunger 102 resists yieldingly movement of the lever 100 in clockwise direction and senses the torque reaction in the ratchet ring member 33. Furthermore the plunger 102 controls the air pressure in a pressure fluid conduit 106 connected to a servo motor 107 in which a servo piston 109 is reciprocable. The conduit 106 extends from an internal annular groove 108 in the cylinder 104.

The embodiment in FIG. 7 is to be used on a guide frame similar to the one shown in FIG. 1 and having a pressure fluid driven feed motor 48 and an automatic control valve 110 thereon for controlling the

conduits

88, 87 connecting the supply conduit 72 to the motor 48. In the example shown the control valve 110 is modified to include a slide 111 reciprocable in a valve bore therein. In a rst position, FIG. 7, the slide 111 connects the supply conduit 72 to the conduit 87 via 4a slide groove 113 provided on the slide 111. Another slide groove 112 on the slide 111 axially separated from the groove 113 by an intermediate land 119, connects the conduit 88 to an exhaust passage 114. The opposed edge portions of the land 119 are chamferred for suitably throttling the pressure fluid flow passing the land 119 when it registers with the supply conduit 72. The slide 111 is biased to its first position by a spring 115 interposed between the housing of the control valve 110 and a ange 116 on the side 111. Furthermore the piston 109 of the servomotor 107 is connected to the slide 111 by means of a piston rod 117. When the servomotor 107 is pressurized via the conduit 106, its piston 109 moves the slide 111'to a second position thereof in which the slide groove 1,12 connects the conduit 72 with the conduit 88 while the conduit 87 is exhausted via the valve groove 113 and an exhaust passage 118 provided in the control valve 110.

The pressure in conduit 106 is controlled by plunger 102 by means of a bleed reduction arrangement including two diametrically spaced tapered axial grooves 121, 122 cooperating with the annular groove 108 of cylinder 104 and having their bottom portions parallel with one another. The axial groove 121 is connected to the live pressure in cylinder 104 via a passage 123 in the plunger 102. The other groove 122 is connected to an exhaust passage 124 extending axially through the plunger 102 to the outer end thereof. The disposition of the axial grooves 121, 122 is such as to provide in the position depicted in FIG. 5 a maximum throttling of the passage 123 and a maximum bleed from the annular groove 108 via passage 124, resulting in substantially atmospheric pressure in conduit 106 and servocylinder 107 unable to move the servopiston 109 against the bias of spring 115. With depression of plunger 102 the throttling and bleed are successively decreased and the pressure in conduit 1,06 rises accordingly causing a corresponding movement of the piston 109 and slide 111 to the right when viewed in FIG. 7.

In operation, a sticking tendency of the drill steel will as before cause an excessive torque load on the ratchet ring member 33 and the arm 100 will be turned in clockwise direction when viewed in FIG. 7 to a greater or lesser extent depending on the drilling resistance. This causes a corresponding riseof the pressure in conduit 106 and movement of the piston 109 whereby the feed motor is throttled by land 119 or reversed by the

grooves

112, 113 to reduce the feeding force on the drill steel 27 and to overcome the sticking tendency in full analogy with the operation of the embodiment disclosed in connection with FIGS. 1-6.

In the embodiment shown in FIGS. 8, 9 the rock drill 20 has connected thereto a separate rotation motor 130 bolted to .a transmission hou-sing 131 at the front end of the rock drill 20. The motor is a reversible pressure fluid driven motor of conventional rotary vane or piston type and the drive shaft 132 thereof is journalled in bearings 133 in the housing of motor 130. The shaft 132 carries rotatably at the outer end thereof a bushing 134 with a sprocket wheel 135 formed integral therewith. The sprocket wheel 135 is via a transmission chain 136 in direct engagement with a sprocket wheel 138 forming an integral part of a drill chuck 139 which is mounted rotatably in the front end portion of the rock drill 20. The chuck 139 has the usual internal surfaces for slidable but non-rotatable engagement with the shank of the drill steel 27.

At the outer end of the bushing 134 the drive shaft 132 carries a radially protruding driver arm 140 which is anchored in a diametrical through bore 142 provided in the shaft 132. The arm 140 transmits driving torque to an arm 141 formed integral with the bushing 134. The driver arm 140 is movable relative to the bushing 134 between a normal position depicted by full lines in 9 and a yielding position represented diagrammatically by the broken line 143 and these two limit positions are defined by axial lugs 144 provided in the outer end face of the bushing 134 and cooperating with the driver arm 140. Pivotally connected to the outer ends of the

arms

140, 141 is a cylinder and piston means 145 such as a hydraulic power jack. One end of the jack, for example the outer end of the cylinder 146 thereof, is pivoted at pivot 147 to the arm 141 while the outer end of the piston rod 148 thereof is pivoted at pivot 149 to the driver arm 140. A spring 150 is interposed between the inner end of the cylinder 146 and the outer end of the piston rod 148 tending to keep the two

arms

140, 141 in their maximally separated position, FIG. 9. c

Hydraulic uid lills the interior of the cylinder 146 and a conduit 151 communicates the fluid in cylinder 146 with an axial bore 152 provided in the outermost portion of the shaft 132. This outermost portion 153 is received sealingly and rotatably ina socket 154 communicating via a conduit 155 via a hydraulically actuatable control valve, not shown, similar to the one disclosed in connection with FIGS. and 6.

In operation the rotary motor 130 rotates shaft 132 and the arm 140 thereon, which normally occupies the position in FIG. 9. The driving torque is transmitted by the jack 145 to the arm 141 of the bushing 134 and via the transmission chain 136 on to the chuck 139 and the drill steel 27. At a tendency of the drill steel 27 to stick during drilling, the resistance to rotation is sharply increased and an increased torque load is overcome by the rotation motor 130 and sensed by the jack 145 by compression of the spring 150 and movement of the driver arm 140 towards the relative position 143 thereof with respect to the arm 141. Thus the jack is contracted and the uid in the cylinder 146 thereof is forced into the conduit 151, the axial bore 152 and conduit 155 to act on the control valve 70, not shown, which will operate in full analogy with the description given above in connection with FIGS. 5, 6. Thus movement of the control valve 70 as before causes overcoming of the sticking tendency and a reduction of the torque load, whereupon spring 150 returns the jack 145 to its extended position shown in FIG. 9.

While in FIGS. 1-4 there are shown torque sensing means disposed externally of the rock drill, the embodiment in FIGS. -12 discloses the corresponding means provided internally of the rock drill in the backhead thereof. In FIG. 10 the rie bar 30 of the rock drill 20 is mounted rotatably in a bushing 160 forming part of the rock drill and is directly connected at the rear portion thereof to a ratchet ring member 161 which thus rotates in unison with the rie bar 30. A short cylindrical stud 162 centrally Iand rearwardly of the rifle bar 30 provides a forward journal for a pawl carrier 163 which at the rear end thereof is journalled pivotally on an inner stud 164 on the backhead 165 of the rock drill 20. An arm 166 projects radially from the pawl carrier 163 and carries a rearwardly directed pin 167 thereon. Furthermore the pawl carrier 163 has mounted pivotally thereon four ratchet pawls 168 and spring pressed plungers 169 are mounted slidably in the carrier 163 each for urging one of the ratchet pawls 168 in outward direction to engage the ratchet ring member 161.

The pitch of the rie bar is chosen such as to rotate the cooperating hammer piston, not shown, in a direction opposite to the rotational direction of the hammer piston exemplified in FIG. 1. Consequently the locking direction of the ratchet pawl means is opposite to the embodiment in FIGS. 1 :and 4 and the ratchet ring member 161 forming an integral part of the rie bar 30 is thus prevented from rotation in counter-clockwise direction when viewed in FIG. 12 by a corresponding disposition of the pawls 168 on pawl carrier 163. During locking the torque reaction will tend to rotate the pawl carrier 163 and its pin 167 in counter-clockwise direction when viewed in FIG. 11 and as before such movement is counteracted yieldingly and elastically. To this end there is provided a transverse bore 170 'm the backhead 165 and a plunger 171 has a sliding fit therein and engages thev pin 167 by an annular groove 172. The end of the plunger 171 opposite to the groove 172 is vented to atmosphere by a radial aperture 174 provided adjacent a closure plug 175 threaded into one end of the -bore 170. The opposite end of the bore 170 is sealingly closed by a partition 176 having a central guide bore 177 therein in which an actuating pin 178 is axially slidably mounted. The partition 176' is kept in place against a shoulder in a counterbore'173 to bore 170 by a spacing cylinder 179 and a plug 180 threaded into the outer end of the counterbore 173. The interior of the spacing cylinder 179 is connected to atmosphere via an aperture 181 through said spacing cylinder and the surrounding Wall of the backhead 165.

The actuating pin 178 extends between the plunger 171 and a master plunger 182 which has a tight sliding fit in a cylinder bore 183 provided in the plug 180. The cylinder bore 183 is filled with hydraulic fluid and a conduit 184 extends therefrom for the hydraulic control of a control valve 70 arranged similarly to the

valve

70 or 110 in FIGS. 5 and 7.

When pressure fluid is supplied to the chamber 25 in the backhead 165 and internally of the rear portion of the rock drill 20, a rearwardly directed passage 185 in the backhead 165 connects the chamber 25 with and pressurizes the portion of the bore 170 in which the pin 167 is freely movable. Pressure acting on the inner face of the plunger 171 moves the latter to its right hand position shown in FIG. 1l and the plunger is kept in that position until it is forced to yield elastically by an excessive torque load taken up by the ratchet pawls 168 and the pawl carrier 163. As described above such excessive loads occur when the rock drill tends to stick in the hole, at which instant the plunger 171 is moved to the left in FIG. 1l moving the actuator pin 178 and the master plunger 182 in front of it. Depression of the master plunger 182 causes a corresponding actuation of the control valve 70 as previously described and causes reduction of the feeding force acting on the drill steel and a decrease of the torque load, whereupon the

plungers

182 and 171 are returned to their position shown in FIG. ll.

In the embodiment according to FIG. 13 there is shown a down-the-hole rock drill in which an impact motor beats against a drilling tool 191 slidably but nonrotatably connected to the rock drill 190 which follows the drilling tool 191 into the hole drilled thereby. The rock drill 190 is rotated by drill rod means 192 connected to a pressure uid driven rotation motor 193 supplied with pressure fluid at a connection 194 for rotating the drill rod means 192 and the rock drill 190 connected thereto. The rotary motor 193 is connected to a slide 195 which is reciprocable by a feed motor 48 along a guide frame 45 in a manner similar to the showing in FIGS. 1-4. Similarly to the mounting of the rock drill 20 in the FIGURES 1-4, the rotary motor 193 in FIG. 13 is journalled pivotally on front and

rear bearings

196, 197, respectively, and a master cylinder 60 as well as elastic balancing means are also mounted respectively to sense excessive torque loads and to balance the normal torque developed by the rotary motor 193.

If a tendency to stick occurs during drilling with the down-the-hole drill 190, the drill rod means 192 will impose an increased torque load on the rotary motor 193. In response thereto the elastic means will yield and the master cylinder will cause actuation of the control valve 70 by which the feed motor 48 is controlled to lessen or to eliminate the feeding force acting on the slide 195, the rotary motor 193 and the drill rod means 192 whereupon drilling will continue in a normal way until the next sticking tendency occurs.

What I claim is:

1. In feed control apparatus of the character described for rock drills and having a rock drill carrying a drilling tool, an elongated guide frame, a slide mounted for reciprocation along said guide frame and providing support for said rock drill, and a source of pressure fluid, the cornbination which comprises rotating means mounted on said slide for rotating said drilling tool, a pressure fiuid operated reversible feed motor in ow communication with said source and fixedly mounted on said guide frame, a power transmission operatively connecting said feed motor to said slide for the forward and backward feed movement thereof along said guide frame, an automatic control valve mounted on said guide frame and disposed between said source and said feed motor and movable between a first and a second position thereof for causing forward and reverse operation of said feed motor, elastic means disposed on said slide, a member disposed on said slide between said rotating means and said elastic means and responsive to the torque developed by said rotating means for moving said elastic means in response to excessive torque in said rotating means, and a remote control connection disposed between said member and `said control valve for controlling the movement thereof from said first toward said second position in response to the development of said excessive torque in said rotating means and back to said first position when said torque becomes normal.

2. A feed control means according to claim 1 in which said connection is hydraulic including hydraulically interconnected plungers, one mounted to sense movements of said member and the other mounted adjacent said valve for transmitting movement thereto from said first plunger.

3. A feed control means according to claim 1 in which said connection is pneumatic including valve means and a servo motor interconnected pneumatically therewith, said valve means being mounted to sense movements of said member and coupled to condition said pneumatic connection to cause said servomotor to actuate said control valve in response to movement of said valve means.

4. A feed control means according to claim 1 in which there are provided journals on said slide for rotatably supporting said rock drill thereon about a longitudinal axis coaxial with said drilling tool, said elastic means connected between said rock drill and said slide to balance the torque reaction of said rotating means tending to rotate said rock drill and abutment means on said rock drill providing said member.

5, A feed control means according to claim 1 in which said rock drill is a down-the-hole Idrill carried by drill rod means and a rotation motor on said slide and there are provided journals on said slide for rotatably supporting said rotating means thereon about a longitudinal axis coaxial with said drilling tool, and said elastic means connected between said slide and said rotating means to balance the torque reaction tending to rotate said rotating means and a portion of said rotating means providing said member.

6. A feed control means according to claim 1 in which said impact motor includes a pressure fluid driven reciprocating hammer piston for actuating said drilling tool, said rotating means comprising a drill steel chuck rotatably mounted in said rock drill in driving connection with said drilling tool, and axially slidably engaged by said hammer piston, a rifle nut on said piston, a rifie bar rotatably mounted in said rock drill and cooperating with said nut for rotating said hammer piston when said rifle bar is restrained against rotation, a ratchet and pawl mechanism in said rock drill for restraining said bar against rotation in one direction but permitting rotation thereof in the opposite direction, and said member forming part of said ratchet and pawl mechanism.

7. In feed control means for rock drills the combination comprising a rock drill, an elongated lguide frame, a slide mounted for reciprocation on said guide frame and connected to support said rock drill, a drilling tool carried by said rock drill and actuated thereby to effect drilling of a hole, rotating means mounted on said slide for rotating said drill steel, a pressure fiuid operated bidirectionally rotatable feed motor on said guide frame, a power transmission operatively connecting said feed motor to said rock drill for forward and backward feed movement of said rock drill with respect to said guide frame respectively during forward and reverse rotation of said feed motor, a pressure uid source, a control valve housing mounted on said guide frame and having a pair of axially opposed valve seats therein connected at the inner end thereof to said source, first and second pressure fluid conduits connected to said housing to communicate with the outer ends of said valve seats and to said feed motor for forward and reverse rotation thereof with respective-y ly said first and second pressurized conduit, opposed spring supported pressure reduction valve members in said housing for cooperation each with one of Said valve seats at the outer ends thereof, a yoke connected to said valve members via said spring support thereof and movable in unison therewith relative to said housing between a first and ,a second position for connecting said source through one of said valve seats respectively to said first and second conduit, means on said slide movably responsive to the development of excessive torque in said rotating means, a remote control connection between said torque responsive means and said yoke for moving said yoke between said first and said second position, and spring means for returning said yoke to said first position when said torque becomes normal.

8. A feed control means according to claim 7 in which each said pressure reduction valve member includes a valve body for cooperation at the inner end thereof with the corresponding valve seat, a spring acting on the outer end of said valve body, and a valve plunger adjacent said spring and connected to said yoke for movement therewith to set said valve body for different fiuid pressures by variable compression of said spring.

9. A feed control means -according to claim 8 in which there are provided exhaust opening means in said housing for the relief of respectively said second conduit in said first position of said yoke and said first conduit in said second position thereof, said exhaust opening means in said valve housing being controlled by exhaust passages in said plungers.

10. In a feed control means for rock drills, the combination which comprises a rock drill, an elongated guide frame, a slide mounted for reciprocation on said guide frame and carrying said rock drill, an impact motor in said rock drill, a drill steel carried by said rock drill, a hammer piston in said impact motor for actuating said drill steel to effect drilling of a hole, a drill steel chuck rotatably mounted in Said rock drill in driving connection with said drill steel and axially slidably engaged by said hammer piston, a rifle nut on said piston, a rie bar rotatably mounted in said rock drill and cooperating with said nut for rotating said hammer piston when said rifie bar is restrained vagainst rotation, a back head on said rock drill, a plunger slidable in said backhead, a ratchet and pawl means in said rock drill adjacent said back head for restraining said rifle bar against rotation in one direction but permitting rotation thereof in the opposite direction, a pressure uid operated bidirectionally rotatable feed motor on said guide frame, a power transmission operatively connecting said feed motor to said rock drill for forward and backward feed movement thereof along said guide frame respectively during forward and reverse rotation of Said feed motor, a pressure fiuid source, an automatic control valve mounted on said guide frame for connecting in respectively a first and second position thereof said source to said feed motor to cause respectively forward and reverse rotation of the latter, elastic means in said back head acting against said plunger, said plunger being connected to said ratchet and pawl means to yieldingly resist movement thereof in said one direction against the action of said elastic means,

1 l and a remote control connection'between said plunger and said control valve for moving said control valve from said irst towards said second positionin response to movement' of said'plunger in saidr'one direction and from said second to said first position in response to opposite movement thereof.

11. A feed control means according to claim in which there is provided a transverse bore in said rock drill for slidably receiving said plunger, passage means for supplying pressure uid to said bore foryieldingly actuating one face of said plunger, and means connecting said plunger to said ratchet and pawl means to yieldingly resist turning motion thereof by li'uid pressure acting on said face.

12. In a vfeed control means for rock drills, the cornbination comprising a rock drill, an elongated guide frame, a slide mounted for reciprocation on said guide frame and carrying said rock drill, an impact motor in said rockl drill, a drill steel carried by said rock drill, a hammer piston in said impact motor for actuating said drill steel to effect drilling of a hole, a drill steel chuck rotatably mounted in said rock drill in driving connection with said drill steel and axially slidably engaged by said hammer piston, a back head on said rock drill, a plunger slidable in said back head, a mechanism in said rock drill adjacent said back head for rotating said hammer piston and thereby said chuck and drill steel, said mechanism including ratchet and pawl means, a nut element, and a spirally ribbed element in sliding engagement with said nut element, one of said elements being connected to said hammer piston and the other in engagement ywith said ratchet and pawl means for restraining said other element against rotation in one direction but permitting rotation in the opposite direction, a pressure uid operated bidirectionally rotatable feed motor on said guide frame and operatively connected to said rock drill for forward and backward feed movement thereof along said guide frame respectively during forward and reverse rotation of said feed motor, a pressure fluid source, an automatic control valve mounted on said guide frame for connecting in respectively a first and a second position thereof said source to said feed motor to cause respectively forward or reverse rotation of the latter, a plunger in said back head connected to said ratchet and pawl means to balance the reaction thereof to normal torque transmitted thereby via said elements to said hammer piston and to yield in said one direction under excessive torque, and a connection between said plunger and said control valve for moving said control valve from said first towards said second position in response to yielding movement of said plunger and from said second to said first position when said plunger returns to the torque balancing position thereof.

13. In a feed control apparatus for rock drills having a rock drill, an elongated guide frame, a slide mounted for reciprocation on said guide frame and carrying said rock drill, an impact motor in said rock drill, a drill steel carried by said rock drill, a hammer piston in said impact motor for actuating said drill steel to effect drilling of a hole, a drill steel chuck rotatably mounted in said rock drill in driving engagement with said drill steel, the combination which comprises a rotation motor on said slide and connected to said rock drill, a power transmission between said rotation motor and said chuck for rotating the latter, a pressure fluid operated reversible feed motor on said guide frame and operatively connected to said rocky drill for forward and backward feed movement thereof and of said rotation motor along said guide frame, a pressure fluid source, means providing flow communication between said source and said feed motor, an automatic control valve disposed in said flow communication means for connecting said source to said feed motor to cause respectively forward and reverse rotation of the latter, elastic'means disposed in said power transmission for sensing torque applied thereto and to said chuckand to yield when said torque becomes excessive, and connecting means between said elastic means and said control valve for moving said control valve from said first toward said second position in response to yielding movement of said elastic means and from said second to said first position upon return movement of said elastic means.

1-4. A feed control means according to claim 13 in which said elastic means is a cylinder and piston means contractible against a predetermined spring bias and coupled between a driving and a driven `member in said power transmission to contract under excessive torque load, and a hydraulic actuator connecting the cylinder of said cylinder and piston means with said control valve for movement of the latter in response to contraction and extension of said cylinder and piston means.

15. In feed control means for rock drills the combination comprising a rock drill, an elongated guide frame, a slide mounted for reciprocation on said guide frame, a drilling tool slidably but nonrotatably carried by said rock drill and actuated thereby to effect drilling of a large diameter hole into which said rock drill can penetrate, a rotary motor on said slide, drill rod means connecting said rock drill to said rotary motor for rotating said rock drill in unison with said drilling tool, a pressure Huid operated reversible feed motor on said guide frame and connected to said slide for forward or backward feed movement thereof along said guide frame respectively during forward or reverse rotation of said feed motor, a pressure tiuid source, a control valve connected to said source, rst and second pressure fluid conduits connected to said control valve and to said feed motor for forward or reverse rotation thereof with respectively said first or second conduit pressurized, said control valve having a first and a second position for connecting said source respectively to said first and second conduit, means responsive to the development of a predetermined torque in said rotary motor for moving said control valve from said first position towards said second position, and means for returning said control valve to said first position.

References Cited UNITED STATES PATENTS 1,542,140 4/1923 Bayles 173-9 1,689,596 10/1928 Osgood 173-9 X 1,690,504 11/1928 Rundquist 173-8 2,407,679 9/1946 Paget 173-9 ERNEST R. PURSER, Primary Examiner.