US2298720A - Feed leg control for stoping drills - Google Patents

Description

Patented Oct. 13, I942 FEED LEG CONTROL FOR STOPI NG DRILLS Matthew OFarrell, Detroit, Mich., assignor to Chicago Pneumatic Tool Compa ny, New York,

N. Y., a corporation of New Jersey Application September 20, 1941, Serial No. 4l1,618

This invention relates to control valves for pressure fluid operated tools and like devices. ore particularly it relates to valve assemblies of the kind used to control feed leg pressures during drilling, independently of the throttle valve.

Such valve assemblies are customarily mounted in the rotation handle of the drill and provide an exhaust port control valve, an actuating plunger reciprocable within the handle and a finger piece or button outside the handle secured to the valve plunger. Prior art structures are comprised of a plurality of. unconnected subassemblies making it impossible to handle the valve as a single unit in. inserting it in the tool and removing it therefrom. Further, it heretofore has been considered necessary that the finger piece or button, by which the valve is controlled, be pinned or otherwise detachably secured to the valve plunger, or that the bushing in which the valve plunger reciprocates be of split construction. The cost of the conventional valve structure accordingly is greater than one in which the finger piece may be made integral with the valve plunger and the valve bushing made in a single piece. The latter construction has the additional advantages of greater sturdiness and reliability.

The object of this invention is to overcome the above-recited disadvantages inherent in feed leg release valves of the prior art.

In carrying out this object there has been provided a valve structure of simple and rugged construction which may be completely assembled prior to its insertion in the tool. The valve plunger and finger piece are formed integrally, the plunger reciprocating within a one-piece cylindrical bushing and having a p ppet valve reciprocably mounted thereon and held against axial relative movement by a spring assembly removably -secured in a novel to the inner end of the plunger. The valve plunger and-poppet valve thus may be moved as a unit with respect to the valve bushing, the valve being adapted for engagement with the inner end 01' the bushing to control the flow of pressure fluid therethrough.

Other objects and structural details of the invention will be apparent from the following description when'read in conjunction with the accompanying drawing, wherein:

Fig. 1 is a fragmentary view, partly in longitudinal section and partly in side elevation, of

in rock drills of the stoper type manner 5 Claims. (Cl. 251--137) ring-shaped a stoning drill embodying the present invention.

appearance.

some parts being shown diagrammatically for the sake of clearness;

Fig. 2 is a fragmentary view of the rotation handle, showing the feed leg control valve inlongitudinal section; and I Fig. 3 is a detail view of a slotted washer adapted to be mounted on a reduced portion of the valve plunger end of the valve spring.

Figs. 2 and 3 are on a larger scale than Fig. 1. As shown in Fig. 1,

comprises a cylindrical head block III, the oppomounting for the motor elements which include a reciprocable hammer piston in splined engagement with a rifle'bar IS. .A head 20 or the rifle bar abuts against the head block l0 and cooperates with an encircling pawl and ratchet mechanism IE to effect step-by-step rotation of the rifle bar and hammer piston. A distributing valve assembly I1 is held within the inner end of the cylinder I I by the rifle bar head 20 the head block I through a port 1 8 in the rotation ratchet, and is directed by an automatic action of the valve to alternate ends of the hammer piston. The pressure fluid is supplied to tending into a transverse bore 2| in the head block HI. Also positioned in the bore 2| is a thereby to initiate and terminate the different stages-of tool operation.

The rearwardly extending cylinder l2 constitutes a body is advanced upwardly and forwardlytoward and into the wall or ceiling oi the mine. While drilling the feed leg maintains a steady pressure on the tool, urging it constantly into engagement with the work so that deepening of the drill to serve as a seat for one the stoper type rock drill The front cylinder ll provides a;

hole is reflectcd'in a'corresponding lengthening of the 'feed leg. A laterally extending handle '25 is provided for steadying the tool during its operation, and may 'be used to efiect manual rotation thereof. The rotation handle is removably secured to the tool, being passed through a transverse bore above the throttle valve and held therein by a lock nut 26 in threaded engagement with the projecting inner end of the handle.

The compressed air passages'leading from inlet bore2l to the feed cylinder I2 are indicated diagramatically inFig. 1. 'As there shown, a passage 21, controlled -by"-throttle valve 22, is connected througha longitudinal passage 28 in the rotation handle with a passage '23 opening into the feed cylinder 12 aboveithepiston '23. Thus, when the throttle valve is'set in a position to-admit pressure fluid to the passage 21 and thence to the feedfleg, theipressure established within the feed .cylinder'is'extended alsoto the longitudinal bore 28in the=rotation handle 25. This disposition of 'fiuidsupply-passages makes possible an auxiliary control of the air pressure inthefeedleg by variably reducing the pressure within the rotation handle. Such pressure control is accomplished by connecting thepassage 28 to an exhaust port and selectively opening and closing the exhaust port as the character of the work shall require. During normal :drilling operations the exhaust port is closed. However, when the drill steel en- -cunterseither a soft or an unusually hard fortionsthroughoutoperation ofthe tool. The pressure within the 'feed leg is also reduced in this manner when lowering the machine from the work attheen'd of a drilling operation. Preferably the auxiliary control of feed leg pressures is effected through an exhaust port control valve located for convenient manipulation in the rear of the rotation handle.

The air feed control valve is the subject of this invention, and, as shown in Figs. 1 and 2, is comprised of a structure 3| positioned within a counterbore or recess 30 at the outer end of handle bore 28. The exhaust port controlled by the valve structure isindicated at 32, and is seen to connect the eounterbore 30 to an open-chamber 33inthe laterally extending grip portion of the rotation handle.

The principal elements of the assembly 3! are a-cylindrical bushing 34, a plunger '35 extending through the bushing, and a valve 36 reciprocably mounted on the projecting inner end of the plunger and adapted for engagement with the :inner end of the bushing. The valve bushing has a screw threaded engagement with the wall :oi bore 30 and is formed with ahead 31 shaped to receive a wrench andefiective to limit movement of the bushing into the eounterbore. The

internal formation of the bushing 34 provides a a longitudinal bore .38 in which the shank of plunger-35 1185 a sliding 'flt. At the front of bore 38 1a eounterbore 38 is formed receiving a head 4| plunger-35. =A=coil spring is confined within the eounterbore 39 by the head 4| and urges the plunger 35 outward or toward the right as viewed in the drawing. At the inner end of bore 38a eounterbore 43 is formed which communicates through a series of ports 44 with an annular groove 45 in the outer surface of the bushing 34. The groove 45 is adapted to register with the exhaust port 32 and when so positioned connects the c;unterbore 43 to atmosphere.

Communication between the eounterbore 43 and the rotation handle bores 28 and 30 is controlled by the valve 36 which has a beveled surface 46 complementing a similar surface on the inner end of the bushing 34. The valve 36 has the shape of a ring encircling a reduced stem-like portion of the plunger 35. A coil spring 4'! surrounds the plunger below the valve 36, being arranged between the valve and a spring base comprising a washer 48 removably attached to the inner end of the plunger. By the pressure of spri g 41 the valve 36 is urged into engagement wi. a limiting shoulder 49 on the plunger 35. Thus, the plunger 35, valve 36, spring 41 and washer 48 constitute a unitary assembly pressed outward by the spring 42 and limited in such movement by engagement of the valve ring with the seating surface at the inner end of bushing 34. The limiting shoulder 49, on plunger 35, is also formed as an annular valve seat and prevents seepage of pressure fluid around the inner periphery of the valve 36. Normally, therefore, the counterbore 43 in bushing 34 is closed and the escape of pressure fluid therethrough prevented. If, however, the plunger is pressed inward the entire assembly of which the valve 36 is a part moves inward, causing the valve to move out of seated position with respect to bushing 34, and thereby opento exhaust the ports and passages leading to the feed cylinder Ill. The head of valve plunger 35 extends outside the bushing 34 andhas a portion 5| of enlarged diameter on its outer end, serving as a push button and as a means for limiting inward movement of the valve assembly.

Since the entire plunger assembly moves as a unit, the spring 41 has no function other than to urge valve 36 so firmly against shoulder 49 that for mechanical purposes the valve and shoulder may be considered integral. The spring 41 therefore can be made considerably stiffer than spring 42 which must be so calibrated that it can be compressed easily by thumb pressure. As shown in Figs, 1 and 3, the spring base washer 48 ms a c shape being slotted in order that it may be mounted on the plunger 35 by a lateral movement causing it to embrace a peripheral cut-out portion 52 (Fig. 2) in the stem of the plung r. The cut-out portion 52 defines an annular flange 53 at the inner extremity of the plunger, against which the washer 48 is pressed by spring 41. The inner periphery of C washer 48 has twc diameters, the portion of larger diameter encompassing flange 53 for more than half its periphery to prevent the washer from slipping laterally of! the plunger, and the portion of smaller diameter having a sliding fit within cut-out portion 52 to prevent removal of the washer by an axial motion.

Thevalve structure 3| is assembled by placing the-spring 42 upon the shank of plunger 35 and then passing the plunger through the bushing 34, the spring 42 being thereby confined within the eounterbore 39. The valve 36 then is slipped over the flange 53 and moved toward the shoul- (ler 49 on the plunger. The spring 41 follows the valve 36 and is compressed sufficiently to permit O washer 48 to be placed-within the peripheral cut-out 52'between spring" and flange 53; When released, the spring 41 urges washer 48 against theflange 53 and thejvalve 36 againstvalve seat shoulder 49. The spring 42 acting on the head 4| of theplunger presses ,the plunger and associated elements outward causing the valve 36 to engagethe inner end of the bushing 34, the several parts thus assuming normally the positions here illustrated. The completed assembly, may be screwed into the counterbore 30 until the bushing head 31 is seated against-the i rear of the rotation handle. ,In the fully inserted position of the bushing the peripheral groove 45 therein is aligned with exhaust port 32.

What is claimed is:

1. In a pressure fluid operated tool or like device having a recess supplied constantly with pressure fluid and a pressure fluid passageway opposite or inner and outer ends of said bushing,

a series of radial ports in said'bushing communicating the inner of said counterbores with the said pressure fluid passageway, a plunger slidably mounted in the longitudinal bore in said bushing and having inner and outer ends pro jecting beyond the respective ends of said bush-' ing, a head on the outer end of said plunger extending into the outer one of the counterbores in said bushing, acoil spring confined in said outer counterbore by the head of said plunger and acting to press said plunger outward, a ringshaped valve reciprocably mounted on the inner end of said plunger, a slotted washer embracing the inner end of said plunger, acoil spring interposed between said valve and said washer, abutment portions on said plunger limiting move-- ment of said valve and said'washerby said spring, and complementary tapered seating surfaces on one of said abutment portions and the inner periphery of said valve forming a valvular connection preventing the escape of pressure fluid around the inner periphery of said valve, the outer periphery of said valve being adapted for engagement with the inner end of said bushing to close and open the inner counterbore in said bushing and thereby cut off and establish communication between said recess and said pressure fluid passageway, and the assembly comprising said plunger and said valve being reciprocable as a unit within said bushing to seat and unseat said valve with respect to said bushing.

2. In a pressure fluid operated tool or like device having a recess supplied constantly with pressure fluid and a pressure fluid passageway leading from said recess, a manually operated valve structure positioned in said recess to control the flow of pressure fluid through said passageway, said structure being inserted in said recess and removedthereirom as a unit and comprising a cylindrical bushing the outer periphery of which is threaded for engagement with a complementary surface in said recess, a longitudinal bore in said bushing, counterbores in the opposite or inner and outer ends of said bushing, a

series of radial ports in said bushing communiouter ably mounted in the longitudinal bore'in said bushing and having inner and outer ends projecting beyond the respective ends of said bushing, a head on the. outer end of said plunger extending into the outer one of the eounterbores in said bushing, a first coil spring confined in said and acting to press said plunger outward, a ringshapedyalve 'reciprocably mounted on the inner end ofsaid plunger, a slotted washer embracing the inner end of said plunger, a second coil spring,

interposed between said valve and said washer, abutment portions on said plunger limiting movement of said valve and said washer by said second spring, and complementary tapered seating surfaces on one of said abutment portions and said, valve forming a valvular connection preventing the escape or pressure fluid around .head of said plunger to unseat said valve with respect to said bushing and permit the flow of pressure fluid from said recess through said inner counterbore and thence to said pressure fluid passageway.

3. A valve structure, comprising a cylindrical bushing, a longitudinal bore in said bushing, a plunger extending through said longitudinal bore and adapted for manually controlled reciprocable movement therein, said plunger having first and second ends extending outside corresponding ends of saidbushing, a counterbore in the first end of said bushing forming a fluid passageway through said shaped valve reciprocably plunger outside the first spring base removably attached to the first end of said plunger, a coil spring surrounding said plunger and interposed between said spring base structure, a ringmounted on said and said valve thereby to urge said valve toward the adjacent end of said bushing, said valve being adapted to seat against said bushing to prevent the flow of pressure fluid to and from said counterbore around the outer periphery of said valve, and a valve seat on said plunger engaged by said valve to prevent the flow of pressure fluid to and from said counterbore around the inner periphcry of said valve, the assembly comprising said plungensaid valve and said spring base being reciprocable as a unit relatively to said cylindrical bushing to seat and unseat said valve with respect thereto.

4. A valve structure, comprising a cylindrical bushing, a plunger within said bushing and formed with a finger piece projecting from one ,end of said bushing and a stem projecting from counterbore by the head of said plunger 4 part of a pressure end of said bushing, a

plunger between said prising said plunger, said valve, said spring and said spring base being reciprocable as a unit relatively to said bushing to seat and unseat said valve with respect to the adjacent end of said bushing, thereby to control the flow of pressure fluid into said bushing around the outer periphery of said valve.

5. A valve assembly, comprising a reciprocable plunger having an integrally formed finger piece at one end and a stem portion at the opposite end, ,a ring-shaped valve reciprocably mounted on .the stem portion of said plunger, a shoulder on said plunger intermediate said stem portion and said finger piece for limiting movement of said valve in one direction, said shoulder acting as a seat for said valve to prevent the flow of pressure fluid around the inner periphery thereof, a peripheral cut-out portion in the stem of said plunger defining an annular flange thereon, a slotted washer embracing said cut-out portion and positioned between said valve and said annular flange, and a coil spring interposed between said washer and said valve pressing said valve into engagement with said shoulder and said washer into engagement with said annular flange.

MATTHEW OFARRELL.

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