US2177391A - Blowing device for rock drills - Google Patents

Description

0d. 24, 1939. E B, LEAR' 2,177,391

BLOWING DEVICE FOR ROCK DRILLS Filed Nov. 5., 1938 2 sheets-Sheet 1 4 I I Sg] k I f5 /J Vial .1.. 5g |55@ 4f 6| I a 4 JLM l ze A5 -20 l 3 I e 3 Zf/ 27 t 19 J 5f I i fa., 50 f 7n I 47 Y 65 5/ f4 INVENTOR ,45- TqE-. 5A/e.

Q I M ATTORNEY Patented Oct. 24, 1939 UNITED STATES 4PATENT OFFICE BLOWING DEVICE FORVROCK DRILLS Application November 5, 193s, serial No. 239,067

2 claims. (o1. 121-10) This invention relates to rock drills and more particularly to an arrangement for delivering a continuous stream of compressed air through the ydrill steel for blowing detritus out of the drilled hole whenever the usual intermittent supply of air is insufcient to keep the hole clean.

An object of the invention is the provision of a blowing device that is simple in construction, easy to manipulate and dependable in operation.

Another object is to adapt the blowing apparatus to be incorporated in a conventional rock drill without requiring extensive alteration of the latter for this purpose.

Other objects and features will appear more clearly from the following description taken in connection with the accompanying drawings and appended claims.

In the accompanying drawings Fig. 1 is a longitudinal section of a fragmentary portion of a rock drill embodying the invention, showing the blower valve arranged in the drilling position; and

Fig. 2 is a similar view on a larger scale showing the valve arranged in the blowing position.

In the illustrative embodiment of the invention `2li the drill comprises a cylinder 4 providing a piston chamber 5 in which a hammer piston 6 reciprocates, the machine being provided with conventional rotation mechanism for imparting stepby-step rotary movement to the piston. Such mechanism may comprise a rifle nut 'I screwed to the piston, a rifle bar 8 having helical splines slidably engaging the rifle nut, a head 9 on the rifle bar, a series o-f pawls I0 carried by the head, and a stationary ratchet ring I I surrounding the head and pawls. The ratchet ring is supported by the cylinder 4 and by a back head I2 rigidly secured to the cylinder.

I The cylinder has a counterbore I3 which'receives a valve chest comprising a valve case I4 and valve cap I5. The valve cap abuts against the ratchet ring I I to prevent axial movement of the latter. The valve cap has an annular projection or sleeve I6 forming a bearing for the rifle bar 8 and surrounded by the valve case I4. The interior of the valve case is recessed to provide a plurality of spaced grooves or chambers which forconvenience may be designated as follows: `rear end groove I'I which is in constant cornmunication with the rear end of the piston chamber by means of ports I8; live air groove I9, continuously supplied with pressure fluid; front end groove 20 communicating by'means of passageway ZI with the front end of the piston chamber; exhaust groove 22, vented toatmosphere; l and an annular chamber 23.. n

lpiston chamber. vmits live pressure fluid from the supply groove An annular distributing valve 25 is mounted for limited axial reciprocation on the valve cap extension I6. The valve and valve cap extension yhave complementary engaging surfaces of different diameters providing a shoulder 26 on the 5 inside of the valve which is adapted to be supplied with live pressure uid constantly tending to move the valve forward. Near its rear end, the valve 25 has a flange 21 projecting into the chamber 23 of the valve chest and dividing said chamber into two separate sections. The section in front of the flange Z'I is vented through port 28. The section in back of the ange connects with a port 29 adapted to be connected (by means hereinafter described) to a cylinder port 3B. The 15 piston chamber 5 has a main exhaust port 3| adapted to be connected to atmosphere when the machine is conditioned for the drilling operation. The port 30 is disposed to the rear end of the main exhaust 3I. 20

The back head I2 is provided with a manipulative throttle valve 33 adapted, when in the open position, to supply compressed air to an annular groove 34. The air passes from groove 34 through the space separating the rie bar head 9 from the 25 ratchet ring II, to an annular groove 35 in the valve cap I5. Passages 36 and 31 deliver live air from the annular groove 35 to the internal shoulder 26 on the valve and the live air groove I9, respectively. 30

'The operation of the mechanism described up to this point is as follows: Assume that the parts are as shown in Fig. 1 with the piston 6 and the distributing valve 25 in their forward positions. Pressure fluid passes from the live air groove I9, 35 over the valve groove 39 to the groove 20 and passageway 2| leading to the forward end of the piston chamber. rlhe piston moves rearward since the rear end of the piston is vented through the main exhaust port 3l. In its rearward travel, 40

`the piston covers the main exhaust and, after closing port 30, compresses the air trapped in the rear end of the piston chamber. The pressure of the trapped air acts against the area at the front end of the valve 25 (in groove I'I) and, when this 45 pressure reaches the proper value, it overcomes the opposing pressure on the internal shoulder 26 to trip the valve rearwardly.

When the distributing valve 25 is in its rearward position, as illustrated in Fig. 2, the valve groove 39 connects the front end groove 20 with the exhaust groove 22 to vent the front end of the At the same time the valve ad- I9 to the rear end groove I'I from whence the air 55 passes through the openings`I8 to the rear end of the piston chamber, thus driving the piston forwardly. At the start of the forward travel of the piston, the air in front of the piston head is vented through the main exhaust port 3 I. As the piston closes the main exhaust port, the air in front of the piston head is exhausted through the passageway 2|.

During its forward travel, piston 6 uncovers port 30 thereby allowing pressure fluid from the rear end of the piston chamber to enter the valve chest port 29 and chamber 23, where it acts on the rear face of the valve flange 21. The combined area of the rear face of iiange 21 and the shoulder 26 is considerably greater than'the area.

of the front end of the valve and consequently the valve trips forward to the Fig. 1 position, thus completing a cycle of operation.

If desired, an exhaust port 4I may belconnected to the rear end of the annular chamber 23 in the valve chest inorder to vent the uid in this part of the chamber before the opposite compression stroke 'of the valve takes place. Port 4I, however, should be restricted in diameter in order to permit pressure to build up in chamber 23 when the piston uncovers the port 30 during its forward movement.

The drilling operation is substantially the same as in prior constructions. The present invention is directed to the arrangement for permitting live air to pass in ra continuous stream through the drill steel while the piston is held stationary. As seen in Fig. 1, the front end of the piston has a central bore 43 registering with the bore 44 in the drill steel 45. According to the present invention, the piston is held in the position shown in Fig. 1 while the main exhaust port SI is closed and pressure fluid is delivered to the rear end of the piston chamber 5 from whence it passes between the splines on the riiie bar 8 and ride nut 'I to the piston bore 43 and drill steel Vbore 44 to blow the detritus from the bottom of the hole being drilled.

For this purpose, the cylinder 4 is provided with a housing 41 in which is secured a valve chest 48. The valve chest has an exhaust port 49 leading to atmosphere. A blower valve 5U, mounted for turning movement in valve chest 48, has a recess 5I `adapted to connect the cylinder exhaust port 3| with the valve chest exhaust port 49, when the blower valve is adjusted to the Fig. 1 position. Another recess 52 is adapted to connect port 3|] with a passage 53 leading to the port 29 in the valve chest I4 to effect forward tripping of the valve in the manner hereinbefore described.

When the blower valve is adjusted to the blowing position, as shown in Fig. 2, the main cylinder exhaust port 3I is cut off from communication with the atmospheric port 49. Passage 53 is disconnected from the port 3l) and is connected to atmosphere by a port 54 in the blower Valve 50, for the purpose of relieving any pressure that might build up at the rear face of the distributing valve flange 2l. Assuming the distributing valve is in the kposition shown in Fig. 2, compressed air is delivered `by the supply groove I9, through groove I'I and ports I8 to the rear end of the piston chamber 5, from whence the compressed air passes through the piston 6 and drill steel 45 to remove the detritus from the bottom of the drilled hole. l The valve is held in the Fig. 2 position by the pressure acting against the front end of the valve which predominates over the pressure against internal shoulder 26 and is unopposed by any pressure against the rear face of flange Z'I.

When the drill is used as a sinker and if the blower valve is closed before the throttle valve 22 is opened, both the piston and the distributing valve will be in the lower or forward position as shown in Fig. 1. In order to insure movement of the distributing valve to the Fig. 2 position under these conditions, a restricted port 56 may be provided between the live air groove I9 and the rear end groove I1 in the valve chest I 4. The purpose of the restricted port 56 is to permit a gradual leakage of pressure fluid into the rear end of the piston chamber until the pressure therein increases to an amount sufficient to trip the valve to 4the Fig. r2 position by acting against the front end thereof. The restricted port 56, while useful as aprecautionary measure is not indispensable, since there may be sumcient leakage between the grooves I9 and ILV-due to the slight clearance at the periphery of the distributing valve.

What is claimed is:

.1. A rockvdrill comprising a ycylinder providing a piston chamber, 4a piston reciprocable therein, said cylinder having 'a main exhaust port separating the front and rear ends of .the piston chamber and adapted to be overrun by the piston in both directions, `a source of live pressure fluid, means 'including 'anautomatic distributing Valve for distributing pressureuid from said source to fthe respective lends of the piston chamber, said distributing valve having a rst area in constant communication with the rear end of the piston chamber and intermittently exposed to live pressure uid and fluid compressed by the rearward movement of the piston for moving the distributing valve in one direction, a second area opposed to said rst-area and of larger extent and intermittently exposed to fluid pressure under control of the piston for moving the distributing valve in the oppcsitedirection, said piston being adapted to deliver impacts against a drill steel and having a bore adapted to deliver pressure fluid to the drill steel for blowing purposes, a blower valve housing 'carried by the cylinder, a blower valve adjustably mounted therein, said blower valve and housing having complementary ports and passages adapted in one position Vof the blower valve to connect the main cylinder exhaust port to atmosphere and the second area on said distributing valve to a port at the rear portion of the piston chamber to condition the drill for drilling operation, said complementary ports and passages being adapted in another position of adjustment of the blower valve to close the main cylinder exhaust port from atmosphere and disconnect said second area on the distributing Valve from .itsassociated piston chamber port and connect said second area to atmosphere to hold the distributing Valvey and piston in a position for dtelivering air throughsaid piston bore to the drill s eel.

2. A rock drill comprising a cylinder providing .a piston chamber, a piston reciprocable therein, said cylinder having a. main exhaust port separating the front and rear ends of the piston chamber kand :adapted to be Yoverrun by the piston in both directions, a source of live 'pressure fluid, means `including an automatic distributing valve for distributing pressure fluid from said source to the respective ends of the piston chamber, said distributing valve having a first area in constant communication with the rear end of the piston chamber and intermittently exposed to live pressure fluid and fluid .compressed by the rearward movement of the piston for moving the distributing Valve rearwardly, a second area opposed to said iirst area and of larger extent and intermittently exposed to fluid pressure under control of the piston for moving the distributing valve forwardly, a third area of less extent than and opposed to said first area and continuously exposed to live pressure fluid under constant pressure for assisting in the forward movement of the distributingvalve and holding it in its forward position when pressure on said second area becomes relatively low, said piston being adapted to deliver impacts against a drill steel and having a bore adapted to supply pressure fluid to the drill steel for blowing purposes, a blower valve housing carried by the cylinder, a blower valve adjustably mounted therein, said blower valve and housing having complementary ports and passages adapted in one position of the blower valve to connect the main cylinder exhaust port to atmosphere and the second area on said distributing valve to a port at the rear portion of the piston chomber to condition the drill for drilling operation, said complementary ports and passages being adapted to another position of adjustment of the blower valve to close the main cylinder exhaust port from atmosphere and disconnect said second area on the distributing valve from its associated piston chamber port and connect said second area to atmosphere to hold the distributing valve and piston in a position for delivering air through said piston bore to the drill steel, and a restricted passageway constantly delivering a minute stream of live pressure fluid from said source to the rear end of the piston chamber to gradually build up pressure in the latter to trip the valve to its rear position, in opposition to pressure against said third area.

EARL B. LEAR.

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