US2062992A - Rock drill - Google Patents

Description

E. G. GARTIN' Dec. 1, 1936.

ROCK DRILL Original Filed Dec. 22, 1933 n 1TV M H N a N mG m @N A Y 6 B Patented Dec. 1, 1936 UNITED" STATES PATENT QFFIQE ROCK DRILL Elmer G. Gartin,

Massachusetts a corporation of Original application December 22, 1933, Serial Divided and this application August 27, 1934, Serial No. 741,620

2 Claims.

This invention relates to pressure fluid motors, and more particularly to improvements in the fluid distribution means of a pressure fluid motor of the pressure fluid actuated, reciprocating hammer piston, type.

An object of this invention is to provide an improved pressure fluid actuated hammer motor of the reciprocating piston type. Yet another object is to provide an improved pressure fluid actuated hammer motor having improved valve means for controlling the fluid distribution means therefor. These and other objects of the invention will, however, hereinafter more fully appear.

This application is a division of my copending application Serial No. 703,580, flled December 22, 1933.

In the accompanying drawing there is shown for purposes of illustration one form which the invention may assume in practice.

In this drawing,-

Fig. 1 is a mongrel longitudinal section through theillustrative form of the improved pressure fluid motor.

Fig. 2 is a view similar to Fig. 1 showing the fluid distributing valve and motor piston in a different position.

In this illustrative construction there is shown a pressure fluid motor of the reciprocating piston, hammer type especially designed for use in rock drills and comprising a motor cylinder l having a bore 2 containing a reciprocable hammer piston 3. The motor cylinder has a front head 4 arranged within a bore 5 formed in a chuck housing or frame 6 to which the motor cylinder is suitably secured. The motor cylinder is provided with a rear head block I having secured thereto in non-rotatable relation with respect thereto a rear head member 8; and the elements 1, 4, 6, l and 8 are held in assembled relation in any suitable manner. The hammer piston 3 is formed with a forwardly projecting striking bar 9 guided within a bore 9 formed in the front head l, and this striking bar is adapted to transmit the hammer blows of the motor piston to the shank of a suitable working implement it, such as a rock drill steel, suitably supported within the chuck housing 6.

As is usual in rock drill type pressure fluid motors there is provided means operated by the hammer piston for imparting rotative movement to the working implement If) as the latter is percussively actuated by the piston striking bar, and this rotation means comprises a spirally grooved rifle bar H fixed to the non-rotatable head member 8 and projecting within a bore I2 formed within the motor piston 3, the spiral grooves of this rifle bar engaging the spiral lugs of a rifle nut I3 flxed within the rear end of the motor piston. This rifle bar, due to its spiral interlocking engagement with the hammer piston, causes the latter to oscillate back and forth as the same reciprocates, and this oscillatory movement of the motor piston is transformed into an intermittent rotary motion by means of a slip rotation mechanism, generally designated I4, through longitudinal grooves 55 formed on the exterior periphery of the striking bar 9 interlocked with inwardly projecting teeth it formed on a combined chuck nut and grip member H, as clearly described in my copending application Serial No, 703,580 referred to above. Driven through this slip rotation mechanism M is a chuck sleeve 13 rotatably mounted within the chuck housing 6 and having secured thereto a chuck bushing i9 within which the shank of the working implement ill is supported. It will thus be seen that as the working implement is percussively actuated by the motor piston, it is at the same time intermittently rotated through the rifle bar i l and slip rotation mechanism i l. As this rotation means for the working implement is clearly described in the copending application above referred to, and does not enter into this invention other than as regards the particular association of the rifle bar with an element of the valve mechanism, further description thereof herein is unnecessary.

Now referring to the improved fluid distribution means for effecting reciprocation oi the motor piston 3, it will be noted that guided on a reduced cylindrical portion 29 of the head member 8 and surrounding the rear portion of the rifle bar H is a fluid distributing valve 28, herein in the shape of an annular disc and arranged in an annular valve chamber 22 formed in the rear head block I and the head member 3. Arranged within the head block I is a throttle valve 23 having a central fluid supply passage 2& and controlling, through a radial port 25, the flow of pressure fluid from the passage 25 to a passage 26 formed in the head block I and communicating with the valve chamber 22 through an annular chamber El. Formed in the forward face of the member 8 at the rear of the valve H is an annular groove 28 connected through a passage 7 29 with the fluid supply passage 25. Formed on the head member 8 is an annular groove 30 communicating through passages 33 with the valve chamber at the rear side of the valve, and connected through passages 32 and ports 33 with the forward end of the cylinder bore. The valve chamber at the forward side of the valve communicates with the rear end of the cylinder bore through an axial passage 34 formed in the head block 1 and surrounding the rifle bar ll. Pressure fluid is exhaustedfrom the opposite ends of the cylinder bore under the control of the motor piston through a central exhaust passage 35. It will be noted that the head block or rear cylinder head I is provided with a stepped bore, comprising a rearward bore, providing the valve chamber 22 and for most of its length filled by the annularly-grooved cylindrical portion of the head member 3, andfurther comprising a smaller bore providing the passage 34. The cylindrical guiding portion 20 of the member 8 is within the stepped bore, herein within the larger, rearward portion thereof. Head block 1 and h ad member 8 may be regarded as main and supplemental heads.

When the parts are in the position shown in Fig. l the communication of the groove 21 with the passages 28, 32 is cut off by the valve 2|, and pressure fluid flows through the passage 26, annular groove 27, through the valve chamber 22 past the forward face of the valve and through the axial passage 34 to the rear end of the cylinder bore to act on the rear pressure area of the piston to drive the latter forwardly to effect its working stroke, and as a result delivering a hammer blow to the shank of the working implement it When the piston head overruns the exhaust passage 35, the pressure within the cylinder bore at the rear side of the piston head drops 'materially, while the pressure fluid trapped within the forward end of the cylinder bore is compressed, and as a result, the valve 2| is thrown from the position shown in Fig. 1 to the position shown in Fig. 2, the valve being thrown by the compression pressure built up within the forward end of the cylinder bore and the constant pressure in groove 28 acting against the opposing reduced pressure within the rear of the cylinder bore. When the valve is in the position shown in Fig. 2, against the shoulder at the rearward end of the bore or passage 34, the communication of the passage 34 with the valve chamber is cut oif by the valve 2!, and pressure fluid flows from passage 25 and annular groove 21 through the valve chamber at the rear side of the valve, through passages 3i, groove 30, passages 32 and ports 33 to the forward end of the cylinder bore to act on the forward pressure area of the motor piston to drive the latter rearwardly to effect its retraction stroke. As the hammer piston moves rearwardly, the exhaust port 35 is overrun by the front edge of the piston head, thereby causing the pressure of the fluid within the forward end of the cylinder bore to drop materially, while the pressure fluid trapped within the rear end of the cylinder bore is compressed, and as a resultgthe valve is thrown from the position shown in 'Fig. 2 back to the position shown in Fig. 1, against an annular seat surface on head member 8, the valve being thrown by the compression pressure acting on the forward pressure area of the valve against the opposing reduced pressure in the groove 28 acting on the rear pressure area of the valve. These operations'are repeated, in rapid succession to effect rapid reciprocation of the hammer piston during normal operation of the motor.

As a result of this invention, it will be noted that an improved pressure fluid motor of the reciprocating hammer piston type is provided, especially adapted to use in hammer rock drills having improved fluid distribution means. It will further be noted that an improved fluid distribution means is provided for a pressure fluid type motor, having improved valve means whereby the flow of pressure fluid to the motor cylinder is controlled in an improved and more effective manner. These and other uses and advantages of the improved pressure fluid motor will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a rock drill, a hammer motor including a cylinder having front and rear heads, a piston reciprocable in said cylinder, and fluid distribution means for effecting reciprocation of said piston including an axial bore extending through said rear head, a supplemental head secured to said rear head and having a cylindrical portion fitting said rear head bore and an integral forward guide projection extending centrally within said rear head bore, said guide projection cooperating With said rear and supplemental heads to form an annular valve chamber surrounding said guide projection, said rear head providing an annular rearwardly facing valve seat and said supplemental head a forwardly facing valve seat, and a disc valve guided on said guide projection and engageable with said valve seats for controlling the flow of pressure fluid to the ends of the motor cylinder, said rear head bore forming a large axial passage for connecting the forward end of the valve chamber directly with the rear end of the motor cylinder in the rearward position of said disc valve and said disc valve when seated on said annular seat cutting off communication of said passage forming bore with. the valve chamber.

2. In a rock drill, a hammer motor including a cylinder having front and rear heads, a piston reciprocable in said cylinder, and fluid distribution means for effecting reciprocation of said piston including a stepped bore, comprising alined axial bores of different diameters, extending through said rear head, a supplemental head secured to said rear head and having a. cylindrical portion fitting the larger bore and an integral forwardly projecting guide portion extending centrally within said stepped bore, said guide portion cooperating with said rear and supplemental heads to. form an annular valve chamber surrounding the guide portion within said larger bore, said supplemental head forming the rear end wall of the valve chamber and the shoulder at the juncture of the alined bores providing the front end valve chamber wall, said front end wall providing an annular valve seat and said reduced bore constituting means for connecting the front end of the valve chamber directly with the rear end of the motor cylinder, and a disc'valve guided for reciprocation on said guide portion and engageable alternately with the rear end valve chamber wall and the annular valve seat at the juncture of the alined bores, said valve when seated against said annular valve seat cutting oiT communication of said reduced bore with the valve chamber.

ELMER G. GAR'I'IN.

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