US1415957A - Rock drill - Google Patents

Description

w; ALSMITH.

v nocx DRILL. APPLICATION man AUGJ3. 1920.

1,415,957, Patented May 16, 1922.

; NVENTOR TO NEY UNITED STATES PATENT OFFICE.

WILLIAM A. SMITH, P H ILLIPSBURG, NEW JERSEY, ASSIGINOR TO INGERSOLIr RAND COMPANY, OF JERSEY CITY, NEW JERSSEY, A CORPORATION 011 JERSEY.

To all whom it may concern: 3

Be it known that I, lViLLIAM A. SMITH, a citizen of the United States, and a resident of Phillipsburg, county of \Varren, State of New Jersey, have invented certain new and useful Improvements in Rock. Drills, of which the following is a specification.

This invention relates to a fluid actuated rock drill of the hammer type, but more particularly to a machine of this type hav .ing a piston hammer provided with two heads of equal diameter connected by a reduced neck, live fluid pressure being con stantly supplied to the cylinder bore at a point between the limits of travel. of said heads, and distributed to the ends of the cylinder in front of and behind the said heads, so that pressure is intermittently suppliedito and exhausted from said cylinder ends.

A piston of the class described is ordinar- .ily a short stroke piston and the primary objeets of the present invention are to produce a late admission against the rear surface of the rear head on the rearward stroke, in order to give the piston a long back travel, and a late cut-ofi' on the forward stroke in order to give a long admission of fluid pressure against the rear surface of the rear piston head. I am enabled to accomplish these objects by means of a valve controlling communication between forward and rearward admission passages leading to two admission ports, one a forward port and the other located rearwardly of said forward port. The distribution of fluid pressure is in all other respects controlledby the piston itself.

To these ends, the invention is shown .in one of its preferred forms in the accompanying drawings, in which- Figures 1 and 2 are diagrammatic longitudinal sectional elevations of arock drill embodying the invention, showingthe piston hammer in two different positions.

Referring to the drawings, A represents the cylinder of a rock drill having the front head B through which the drill steel G extends in position to receive the impact blows of the reciprocating piston hammer, which in this instance is formed with two heads D and E of equal diameter connected by a reduced neck F. The piston may, if desired be provided with the forwardly extending reduced shank Gr. The cylinder is provided with a main bore H and. the back head J ROCK DRILL.

Specification of Letters Patent. Patented 11 16, 1922,

a Application filed August 13, 1920. Serial No. 403,353.

having the pressure chamber K. The cylinder A and back head J are provided with Sllltitble ports and passages partly controlled by the piston and partly controlled by a valve L for distributing fluid pressure to different portions of the cylinder for actuating the piston.

Actuating fluid as air under pressure is constantly supplied to the cylinder bore from the inlet 0 at a point between the limits of travel of the said two heads D and r E, and the admission port P is open constantly for this purpose. Pressure is intermittently supplied to the rear pressure chamber K in the back head and to the forward end of the cylinder in front of the piston head I). The back head is provided with the exhaust port Q, and the main cylinder bore is provided with the exhaust port R. Admission of fluid pressure to the forward end of the main cylinder bore is controlled solely by the front piston head through the supply port S, passage T and admission port U directly to the front end. of the cylinder.

A forward admission port V comment cates with the valve chamber W by means of the forward admission passage X, and another rearward admission port Y communicates with the valve chamber W by means of the rearward admission passage Z. The rearward admission passage Z comu'iuuicatcs with the rear pressure chamber K in the back head J by means of the passage (1.. The valve I) is provii'led with the forward. and rearward heads 2) and (3: connected by the reduced neck (Z. Opposed. operative pressure surfaces of the valve are subject to fluctuating pressure and in this instancethe forward surface 0 is intermittently supplied with pressure through the passage. f communicating with the supply port S while the rear pressure surface of the valve is intermittently supplied with pressure through the passage it communicating with thesupply passage to. The function of the valve is to control communica tion between the forward admission passage X and the rearward admission passage Z in order to produce a late admission of fluid pressure against the rear pressure surface 7' of the rear piston head E on the rearward stroke and prolong the admission. The piston thus has a longer back travel than customary in rock drills having a piston of this type, and has a later out-off on the forward stroke.

In the operation of the machine, let it be assumed that the piston is at theforward end of its stroke and is about to start on the back stroke as indicated in Figure 1. The rear pressure chamber K in the back head is shown exhausting through the exhaust port Q and pressure is also exhausted from the rear end of the valve L through the passages h, a, and through the chamber K and exhaust port Q. The live pressure on the front surface 6 of the valve L has caused the valve to be thrown to its rearward position as indicated in Figure 1, closing communication between the forward and rearward admission passages X and Z.

In Figure 1, the fluid pressure is being admitted to the front end of the main cylinder bore in front of the piston head D, and as the piston travels back the exhaust port Q for the rear pressure chamber K in the back end is closed and the supply port S to the forward end of the cylinder is closed, but the shoulder 70 at the neck of the piston over-runs the forward admission port V without admitting pressure to the rear surface j of the piston head E, because the forward admission passage X is still closed by the valve L.

After the forward piston head D overruns the cylinder exhaust port R, the exhaust from the forward end of the cylinder is opened, which also opens the front end a of the valve L to exhaust through the passages f and T and through the cylinder bore to the exhaust port'R; The shoulder 70 on the neck of the piston-then over-runs the rearward admission port Y as indicated in Figure 2, which admits pressure past the piston neckF to the rear pressure chamber K behind the piston head E and also admits pressure through the assage ii to the front end 9 of the valve L w iich throws the Valve to its rear position, also as indicated in Figure 2, thus opening communication between the forward alnd rearward admission passages X and Z and supplies full pressure behind the piston head E to drive the piston forward.

Owing to the fact that no pressure is supplied to the rear of the piston head E when the forward admission port V is uncovered by the piston shoulder is, the piston has a substantiallylong rearward stroke, before the forward and rearward admission passages X and Z are placed in communication by the action of the valve L, and on the other hand, the piston is given a late cut-01f on the forward stroke, because cut-oil does not take place when the rearward admission port Y is over-run by the piston shoulder in, but is delayed until the forward admission port V is over-run by the piston as indicated in Figure l.

I claim:

1. In a fluid operated rock drill of the hammer type, the combination of a cylinder and piston having front and rear heads of equal diameter, and a connecting neck of reduced diameter, means for constantly supplying fiuid under pressure to the cylinder between the said two piston heads, a supply port controlled solely by the front piston head and communicating by means of a supply passage with an admission port at the front end of the cylinder for supplying motive fluid directly to the forward end of the cylinder in front of the front piston head, a forward admission port and another admission port rearward of the said forward admission port for supplying motive fluid to the rearward end of the cylinder behind the rear piston head, and a fluid actuated valve for controlling communication between forward and rearward admission passages leading to said forward and rearward admission ports.

2. In a fluid operated rock drill of the hammer type, the combination of a cylinder and piston having front and rear heads of equal diameter, and a connecting neck of reduced diameter, means for constantly supplying fluid under pressure to the cylinder between the said two piston heads, a supply port controlled solely by the front piston head and communicating by means of a supply passage with an admission port at the front end of the cylinder for supplying motive fluid directly to the forward end of the cylinder in front of the front piston head. a forward admission port and another admission port rearward of the said. forwanl admission port for supplying motive Iluid to the rearward end of the cylinder behind the rear piston head, and a fluid actuated valve subject to fluctuating pressure on opposed operative surfaces, for controlling communication between forward and rearward admission passages leading to said forward and rearward admission ports.

In testimony whereof I have signed this specification.

WILLIAM A. SMITH.

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