US1384216A - Rock-drill - Google Patents

Description

W. A. SMITH.

ROCK DRILL.

APPLICATION FILED AUG.I3, 1920.

Patented July 112, 15921,

' warren stares rarest @FFHCE WILLIAM a SMITH, or r'nrtnrrsnune, new :rniasn'r, assrenoa 'ro INGERSOLL- renn n COMPANY, or JERSEY orrr, NEW anrsnr, A ooaroaarrou or NEW 7 JERSEY.

restate,

i ROCK-DRILL.

' Application filed August 13, 1920. Serial No. 403,354.

To all whom it may concern: 7

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

This invention relates to: a fluid actuated rock drill of the hammer type but more par:

ticularly to such a machine having a dilfer f ential double ended reversible piston provided with a main head, and shanks extending in opposite directions from said head and having reduced necks adjacent the main head. In this particular machine fluid pressure is intermittently supplied to and exhausted from'the larger bore of the cylinder in frpnt of and behlnd the main head and also behind the rearwardly extending'shank, so that a fluctuating pressure chamber is provided at the rear or forwardly driving pressure surface of the said shank.

.The primary objects of the invention are to lengthen the back travel of the piston and produce. longer admission of fluid pressure against the rear or forwardlydrivlngpressure surface of the main piston head on the This is accomplished by forward stroke. means of a fluid actuated d1fl'erent1alvalve controlling communication between adinission passages leading respectively to a forward admission-port and another admlssiouu port located rearwardly of said forward admission port. In this instance the valve is.

subjected to fluctuatingjpressure on one of its .difierential opposed operative :surfaces tending to IIIOIVG the valve in a directionto open communication between said forward and rearward admission ports.v In accordance with this invention and as one of \its features, I provide means for constantly subjecting another opposed differential pressure surface of the valve to live air p essure tending to throw the valve over an and close communication between. the sa d forward.

and rearwardadmission ports.

Further objects of theinventi'on willhereinafter appear and to all of these ends the invention is shown in the accompanying drawings in one. of its preferred forms, in

j which- Figures 1 and 2 are diagrammatic longitudinalsectional elevations of a .rock drill embodying the invention, showing the piston hammer in two different positions.

Referring to the drawings, A represents the cylinder of a rock drill having the chuck B through which the drill steel C is inserted in the usual nuanner in position to receive the impact blows of the reversible reclprocating hammer, which comprises the main piston head D having the forwardly and rearwardly extending reduced shanks E and F of the same diameter connected td the main head D by means of the necks G and H.

The main piston head D reciprocates in the larger bore J of the cylinder and the piston shanks E and F slide in bores of smaller diameter, the forward shank operated in the bore K and the rearward shank f operated in the bore L of the back head, 0. The smaller boresK and L are of the same diameter so that either shank may be inserted in either smaller bore to: make the piston reversible in case it is desired to so reverse it. Fluid pressure is supplied to the admission port P in the back head Othrough the inlet Q controlled by the usual throttle valve R and ports and passages are-provided in the cylinder and back head for distributing motive fluid to and from the different portions of the cylinder. in the present instance the two forwardly driving pressure surfaces S and T and the rearwardly driving pressure surface D are all intermittently supplied with pressure and the chamber V in the rearward portion of the back head U is thus a fluctuating pressure chamber to which pressure is supplied through the passage W communicating with the, rear portion of the main cylinder bope J, as indicated in dotted lines in the drawmgs.

j The main cylinder bore is provided withthe main exhaust port X and fluid pressure is supplied to the front end of the main cylinder bore in front of the piston head D through the passages Y and Z in the back head and cylinder respectively.

The supply of fluid pressure to the main cylinder bore behind the main head D is controlled partly by the valve a having a forward head 6 and'a rearward head 0 connected by the reduced neck d and also providedvwith the reduced shank or extension e. The smaller operative surface,- in this I case the rearward surface f of the valve, is

subjected to constant pressure through the passage 9 communicating with the supply passage h from the inlet Q. Another and larger opposed surface j of the valve, in this instance the front end of the valve i'ssubjected to a fluctuating pressure through the passage hcommunicating with the main bore of the cylinder. The valve chamber 0 is open to atmosphere atone point at ,the. port p. .v s

The forward admission'port 9 opens into the smaller bore in the back head and conimunicates with the valve chamber 0 'by" means of the forward admission" passage '1. Another rearward admission passages communicates with the valve chamber 0 by means of the rearward admission passage t, which also communicates with the passage h.

In the operation of the machine let it be assumed that the piston is at the forwardend of its stroke and 'is about to start on the back stroke as indicated in Fig. l. The main cylinder bore is shown exhausting through the exhaust port X and therear fluctuating pressure chamber V behind the rearwardly extending piston shank F is also exhausting asindicated by the arrows; Pressure is exhausted from in front of the pressure surface j of'the valve through the passage It and exhaust port X so that the constantpressure on the rearward surface f of the valve tends to hold the valve iii-its forward position as indicated in Fig, '1,

closing communication between the forward and rearward admission passages rand t.

The piston is ready for the rearward stroke and as it travels back, the exhaust port X to the back of the main head D is closed and 'the supply'passage Z to the forwardend of the cylinder-is also closed by the forward piston extension E, but the shoulder to on v the rearward extension F of the; piston overruns the forward admission port 9, without admitting pressure to the rear surface S of the' main head D, because the rearward adfull pressure be ind the main head-D mission passage 25 is stillclosed by the valve 0. When the shoulder u on the rearward extension of the piston over-runs the rearward 'admissionport s as indicated in Ei 2, pressure is admitted past the piston nec H to the rear of the larger bore J of the cylinder, andfalso through passage K to the front end j'of the valve '11, which throws the valv'eQto its-rear position against the constant pressure exerted on the, smaller .surface f of the valve and communication is opened-between the forward and'rearward admission passa es 1" and 2? thus supplying 1 for driving the piston forward.

Owing to the fact that no pressureis sup-' plied to the rear of the-maincylinder head B when the forward admission port 9 is unsupply covered by the piston shoulder a the piston has a substantially long rearward stroke 'beforethe forward and rearward admission passages r and t are placed in communication by the action of the valvea, and on the other hand, the piston is givena late cut-01f on" the forward stroke, because cut-off does not take place when the rearward admission port 8 is over-run by the piston shoulder a but is delayed until the forward admissionport gis over-run by the'piston as indicated 4 in Fig. .1. Q

I claim: n 1; In a fluid operated rock drill of the hammer type, the combination of a cylinder and reversible piston, means controlled by the piston for supplying motive fluid to v the forward end of the cylinder, aforward' admission port and another admission port rearward of said forward admission port for su plying motive fluid to the rearward end '0 the cylinder, and a fluid actuated valve subjected to fluctuating pressure on one operativesurface'and to constant pres-' sure on anopposed operative surface I for controlling communicationbetween forward and rearward admission passages leading to ,said forward and rearward admission ports. 2. In afiuid operated rockdrill of the hammer type, thecombination of a cylin' der and reversible differential piston subject to fluctuating pressure on one of it's forwardly acting pressure surfaces, means controlled by the pistonfor supplying motive fluid to the rearw'ardly actmg pressure surf-ace of'the piston, a forward admission port and another admission port rearward; of said forward admission port for supplying motive to the other forwardl acting pressure surface of the pistonQan actuated valve subjected to fluctuating pres sure on' one operative surface and to con stant pressure on an opposedoperative surface for controlling communication between forward and rearward admission passages leading to said forward and rearward ad mission ports. 3

3. In a fluid operated rack drill; of the,

, hammer'type, the combination of a cylinder sages leading to said forward and rearward admission ports, said valve being subject to constant pressure on one operative sur- (face tending to close communication be-' tween said forward "and rearwardadmission,

passages and subject to fluctuating pressure on' an opposed operative surface tending toopen communication between said forward and rearward admission passages.

4. In a fluid operated rock, drill of'the hammer t gpe, the. combination of a cylinder and 'r versible difi'erential piston sub- 4 ject to fluctuatingpressure on one of its forwardly acting pressure surfaces, means co'ntrolled by'the piston for supplying .mo-

specification.

valve controlling communication between forward and rearward forward and rearward admission ports, said valvebeing subject to constant pressure on onefoperative surface tending to close communication betweenv said forward and rearward admission passages, and Sub ect to fluctuating pressure on an opposed operative surface tendlng to open communication between said forward and rearward admission passages.

In testimony whereof I have signed this '.WILLIAM A. SMITH.-

admis'sion passages leading to said 1

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