US2562468A - Wet and dry back head for rock drills - Google Patents

Description

Patented July 31, l,1951

WET AND DRY BACK HEAD FOR ROCK DRILLS Earl B. Lear, Detroit, Mich., assignor to Chicago Pneumatic Tool Company, New York, kN. Y., a corporation of New Jersey Application April 29, 1949, Serial No. 90,450`

This invention relates to operating controls for a rock drill, `and more particularly to a backhead having a novel arrangement of live air and water supply passages.

The main object of this invention is the provi- Ysion of a rock drill having a backhead which is s o constructed and arranged that the tool may ,beA operated .dryf i. e., with live air being supplied to the drill steel during drilling operation, or wet, i. e., with waterr being supplied to the drin steel Whse drilling, and further that such Wet operation may be controlled manually, er

automatically, as desired. By means of the invention it is possible to provide four rdifferent backhead combinations for furnishing live air `or water to the drill steel for hole cleaningv purposes, without extensively dismantling the rock fdrill, andv with minimum loss of time in substituting parts.

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

Fig. 1 is a longitudinal section view of the rear portion of a rock drilljof the invention taken through lines I-I of Fig. 2, and showing the backhead arranged for dry operation and with throttle in full-on position;

Aline 4-4 ofFig. 3;

Fig. 5 is a section view of a rock drill of the invention showing the backhead arranged for vwet operation with automatic 'control land with the throttle in full-on position, and

Fig. 6 is a section View of the throttle valve as seen from line '--B of Fig. 2 and featuring the 4 claims. (c1. iai- 10) profile of va notched flange as used on the throttle valve of the rock drill of the invention.

Vhaving a piston chamber I2 formed therein, and

a yhammer piston I3 reciprocable within the chamber to deliver percussive blows to a working implement, such as a drill steel (not shown) fmounted at the front end of the drill.V The piston I3 is slidably mounted on a rifle bar I4 which is caused, by means including a ratchet ring I5, to move in step-by-step rotary movement. Such movement is imparted to the piston I3 in the conventional manner by a nut I6 xed within the piston and engaging helical splines formed on the rifle bar. The reciprocating movement vof the piston I3 is eiected by live air admitted to the tool under the control of an air throttle valve I'I anddirected by a distributing Valve assembly, generally indicated at I8, to alternate ends of the chamber I2. The valve assembly I3 comprises a block I9, a cap 2l, a chamber 22 formed therebetween, and a distributing valve 23 positioned within the barrel II and encircling the shank of the rifle bar I4,

Referring to Fig. 2 it will be seen that the throttle valve I'I is mounted transversely Within the backhead and comprises a central tubular portion 26, a notched flange 21 (Fig. 6) at the left thereof, `a portion 28 of reduced diameter at the right of the valve, anda threaded portion 2S at the extreme right thereof. For the accommodation of the valve I7, the backhead is formed with a central bore 3|, a bore 32 of reduced diameter at the right thereof, and a counterbore 33 at the left thereof. The counterbore 33 is threaded in part for the reception vof the threaded end portion 34 of `an air hose connection 35 (partly shown). The portion 28 of the throttle valve Il projects beyond the backhead and has aiiixed thereto a manually operable lever 36 (partially shown in Fig. 2) which is retained in position by nut 31. The throttle valve is rotatable to move a port 33, formed in the central tubular portion 25 of the throttle valve, into and out `of registry with an air passage 3S formed in the backhead I0. When the throttle Il is moved from initial or inoperative position into itssuccessive operative positions (the iinal operative position being shown in Fig. 1), live air flowing into a throttle chamber 4I within the throttle valve, is permitted to pass through the port 38,

passage 39, reservoir 42, bore 43 of ratchet ring I5, a reservoir 44, a set of circumferentially arranged ports 45 Within the cap 2l, into the dis'- 'tributing valve chamber 22, and thence into alternate ends of the main piston chamber I2, to reciprocate the piston I3 in well known manner.

A bleeder port 38a, in the form of a groove, is arranged on the periphery of the throttle valve and intersects a well of port 38, as seen in Figs. 1 and 6. The bleeder port 38a allows a reduced supply of air to enter the drill for operation at slow speed or under reduced power. I

The notched flange 21 (Fig. 6) cooperates with a plunger 41 (Fig. 2) which functions as a yielding locking means to retain the throttle valve in successive rotative positions to regulate the flow of live air supplied for the operation of the rock drill. Plunger 41 is disposed within a bore 48 formed in the backhead, and is maintained against a notch 49 of the flange 21, when the throttle is in off position, by a compression spring I, arranged in the bore 48 and maintained under compression by a threaded plug 52. As the throttle is rotated toward open position, the plunger will successively engage the intermediate notches 53, which are arranged to cause the throttle valve to supply live air to the drill at reduced pressure by reason of bleeder port 38a.

If a full supply of air is desired the throttle is Y rotated to nal position at which the plunger 41 engages notch 50. In this position of the throttle valve I1, the port 38 is .in registry with the passage 39, and the ilow of air from chamber 4I is unrestricted.

Dry operation For dry operation of the tool it will be seen in Figs. l and 2, that a predetermined portion of live air owing into the reservoir 42 passes rearwardly through port 54 into passageway 55, the lower end of which is closed by a threaded plug 56, into chamber 51, and through apertures 58 in a plug 59 into a bore 6I of said plug, and thence through the longitudinal tube 62 and into the bore of the drill steel (not shown).

As is seen in Fig. 2, vprovision is made for the passage of water to the drill steel by means of a threaded bore 63 located in the lower left hand side of backhead I0, and a passageway 65 con- A necting bore 63 to a receiving chamber in the form of a bore 68 located toward the right side of the backhead. A passageway 61 leads from L bore 68 into chamber 51. A plug 69, having a reduced midportion 1I, is located in the bore 68, the lower end being threaded to removably aiix the plug within the backhead while the upper portion thereof seals a passageway 12 which projects upwardly from bore 68 and intersects the reduced diameter bore 32, the uppermost end of passageway 12 being closed by a pipe .plug 13. When the tool is operated dry, a pipe plug 14 is applied to bore 53; however, as will be further explained, during wet operation of the tool, the flow circuit including passageway 65 as just described, conveys water to the drill steel.

Wet operation The tool is arranged for two possible types of wet operation, namely plain, wherein the flow of water 4is manually controlled from a separate valve in the water delivery line, and automatically, wherein the water control is coupled to and operates with the air throttle valve, as will be fully described hereinafter.

Considering iirst the plain wet operation, reference lis had to Figs. 3 and 4 wherein is shown the substitution of a plug 15 for the threaded plug 56. Plug 15 has an extension terminating in a head which fits the passageway 55 to prevent the flow of air from reservoir 42 through passageway 55 into chamber 51. Pipe plug 14 is removed and a water connection 16 is threadably aixed to bore 63.

If the tool is being prepared for plain wet use exclusively, no other alterations are required, the foregoing adjustments being suilicient to .place the tool in readiness for plain wet operation. If,

on the other hand, there is the possibility that it will be desired to convert the tool to the automatic type, then the plug 69 is removed and a bushing 11 is tted in the bore 68. A plurality of radial holes 18 connect the bore of bushing 11 to an annular lgroove 19 located on the exterior thereof, said groove 19 being in register with the passageway 61 when the bushing is in place in bore 68. A plug 8|, similar to plug 69 but having a stem of reduced diameter, extends within bushing 11, the upper end of the stem being adapted to seal the inner diameter of the bushing just above the radial holes 18, as shown.

It is seen that when the tool is arranged as in Fig. 3, water can ilow from the bore 63, through passageway 65 into bore 68, about the stem of plug 8l through the bore of the bushing 11 and radial holes 18, into annular groove 19, and iinally through ,passageway 61 to chamber 51 and into the tube 62.

This latter plain wet arrangement can be quickly changed to the automatic type by simply removing the plug 8l and inserting a smooth tting valve 82 into the bushing 11, as shown in Fig. 5. A valve head 83 is arranged at the lower end of the valve and is acted upon by a compression spring 84, one end of which engages the valve, While the other end is enclosed in a recessed plug 85 which closes the lower end of bore 68. The valve head 83 is held against the lower end of bushing 11 by the spring 84, thus preventing the flow of water through the bushing. The other end of valve 82 projects a short distance above the upper end of bushing 11 and is arranged for sliding contact with a cam 86 'formed in the portion 28 of the throttle valve I1. When the throttle valve I1 is rotated for tool operation, the cam 86 forces the valve 82 downwardly thus unseating the lower end thereof and permitting water to flow to the drill steel; when the throttle valve is rotated for tool cut-01T, the valve 82 is urged by spring 84 to seating position, whereupon the ow of water to the drill steel ceases. I

In changing from dry operation to wet operation it is desirable, although notl essential, to replace the tube 62. The tube for use in wet operation is preferably longer lthan the tube used for dry operation, and is further arranged to have a reduced diameter portion at the front end thereof. The reason for arranging the wet operation tube in this manner is, iirst, to permit the discharge of water at a point as close as practical to the drill steel, and secondly, the reduced diameter portion provides for an increased rate of discharge velocity.

From the foregoing it is thus seen that the device of the invention is capable of being arranged in any one of four possible combinations (see table following) to provide for three distinct types of service, namely, dry, plain wet, and automatic Wet:

Operation Backhcad Arrangement Dry 1(15? plugsl74, g d

a uscp ugs 5, an water connection 76. Flam Wet {(b) use plugs. 75, 81, bushing 77, and water I connection 76. Automatic wet use plug 75, valve 82, bushing 77, and water connection 76.

It should be apparent that, with the exception of the plain wet arrangement, the ilow of air or water through the tube 62 occurs only during tool operation. As shown in Fig. 1 of the drawing, the tool includes an air valve arrangement 88, which is used for blowing purposes at any time, whether or not the tool is in operation Such a blowing arrangement is similar to that shown and described in the U. S. patent to E. B. Lear, No. 2,177,391 dated October 24, 1939. Normally, the iiow of air through tube 62 supplies only enough air to keep the detritus suspended in the bore hole; the use of the blower arrangement 89 blows the detritus completely out of the bore hole. It will be understood that the air iiow .to the bore hole when using the blower valve, passes on the outside of tube 62, in contrast to the flow of air or water within the tube 62 as when using the arrangement of subject invention.

What is claimed is:

1. A rock drill having a backhead arrangement which can be readily adapted for any-one of a plurality of service requirements and comprising a throttle valve for the control of compressed air to a reservoir, a first passageway leading from the reservoir to a tube which is arranged for the conduction of fluid to the work end of said rock drill, a water inlet, a second passageway leading from said water inlet to a bore which serves as a receiving chamber, a third passageway connecting said receiving chamber to said tube, a first set of removable plug means one of which closes the water inlet, another of which closes both ends of the receiving chamber to condition the rock drill for dry operation, and a second set of removable plug means for the replacement of said rst set comprising a plug for closing ythe first passageway, and a plug arrangement located in the receiving chamber to allow for iiow of water from the water inlet to the tube and having interchangeable parts yto provide for either manual control of the water iiow or automatic control of the water ow by association with cam means on the throttle valve, the second set of plug means being adapted to condition the rock drill for wet operation.

2. A rock drill having a backhead arrangement adjustable for a plurality of service requirements and comprising a throttle valve for the control of pressure iiuid to a reservoir which is formed in part within the backhead, a first passageway which leads from the reservoir to a tube positioned within the rock drill, said tube adapted for the conduction of fluid to the work end of the rock drill, a water inlet in the backhead, a second passageway which leads from the water inlet to the side of a bore forming a receiving chamber, a third passageway which leads from the side of the receiving chamber to the tube, a first set of removable plug means to provide for dry operation of the rock drill and including a plug for closing the water inlet and a plug for closing both ends of the receiving chamber, and a second set of removable plug means to provide for wet operation of ,the rock drill and including a plug yfor closing the first passageway and a plug arrangement adapted to allow for i'low of water from the second passageway, through the receiving chamber, and into the .third passageway.

3. A rock drill having a backhead arrangement according to claim 2, in which the plug arrangement of the second set of removable plug means comprises a bushing positionable in part within the receiving chamber and two interchangeable water control plugs one of which closes both ends of the receiving chamber without restricting ow of water from the second passageway to Ythe third passageway, the other of which is in the form of a valve siidable within the `bushing and operable by cam means located on the throttle valve :to control the flow of water from the receiving chamber into the third passageway.

4. A rock drill having a backhead arrangement according .to claim 3, in which the valve is spring loaded to automatically shut off the iiow of water into the third passageway when the throttle valve is in non-operative position.

EARL B. LEAR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,146,284 Sanders July 13, 1915 1,382,777 Gilman June 28, 1921 1,382,778 Gilman June 28, 1921 1,382,779 Gilman June 28, 1921 1,531,315 Slater Mar. 31, 1925 1,804,066 Smith May 5, 1931 1,941,205 Fuehrer Dec. 26, 1933

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