US2217535A - Rock drill - Google Patents

Description

w. ALEXANDER.

Oct. 8, 1940.

Rock DRILL Filed De. 31". 1937 Patented Oct. 8, 1940 "PATENT OFFICE ROCK DRILL William M. Alexander, Johannesburg, Transvaal, Union of South Africa, assignor to Sullivan Machinery Company, Claremont, N. H., a corporation of Massachusetts l Application December 31, 1937, Serial No. 182,726 In theUnion of South Africa February 4,` 1937 2 Claims.

This invention relates to rock drills, and more particularly to improved hole cleansing means for a hammer rock drill for conducting cleansing liquid tothe bottom of the drill hole to cleanse the cuttings therefrom.

In the drilling of rock, particularly underground in mines, when compressed air or a mixture .of air and liquid is delivered by means of the conventional hole cleansing means of the rock drill to the bottom of the drill hole to cleanse the cuttings from the hole, there is great danger of silicosis. 'I'his pathological condition of the lungs is receiving a great deal of attention from the health departments and legislative bodies of government units. This condition of the lungs is attributed to the action of the siliceous stone dust on the lung tissue, it is believed, and the risk of harm is believed to be greatly increased vwhen water vapor maintains the rock dust in suspension, as occurs when compressed air and Ywater both pass down the drill hole and the air f in its expansion and blowing tends', as it Were, to atomize the water and produce a mist or fog which maintains the stone dust in suspension in the air and perhaps increases its ingress to the x lungs of the drill runner. Various devices to overcome this condition have been attempted, such as water boxes, Vacuum devices, and the like, to eliminate the danger of silicosis, but complete success has not been attained.

An object of this invention is to provide an improved hole cleansing means for a rock drill which, to a substantial extent, eliminates the danger of silicosis. Another object is to provide an improved rock drill hole cleansing means for effecting hole cleansing by the use yof a liquid jet While precluding the entrance of compressed air to the drill hole. It is a further vobject to provide improved means for venting the compressed air from the drill steel chuck of a rock drill so only liquid is conducted to the bottom of the drill hole. A further object is toprovide in a rock drill of the above character anovel arrangement of vent passages for the drill steel chuck. Yet anotherobj ect is to provide improved deflecting means associated with the vent passages for laterally deecting ythe air issuing from the vent passages. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

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

In this drawing- Fig. 1 is a view in longitudinal vertical section through a hammer rock drill with which an illustrative embodiment` of the improved hole cleansing means is associated.

Fig. 2 is an enlarged cross sectional view taken substantially on line 2-2 of Fig. 1.

Fig. 3 is a detail sectional View in perspective showing the improved drill steel chuck.

In this illustrative embodiment vof the invention there is shown' a rock drill generally designated I with which is associated the improved hole celansing means generally designated 2. The rock drill is herein of the pressure fluid actuated hammer type comprising a cylinder 3 having a bore II containing a reciprocatory hammerpiston 5. The hammer piston has a forwardly projectl5 ing striking bar 6 guided at 'l in a bushing 8 supported within a front motor head 9, and the piston striking bar is adapted to deliver impact blows to the shank of a drill steel I0 as will later be described. A pressure fluid actuated distributing valve mechanism II is mounted in a valve box I2 arranged at the rear end of the motor cylin` der, and this distributing valve is adapted to control the supply of pressureV fluid through suitable passage means to the motor cylinder to effect reciprocation of the hammer piston in the manner Well known to those skilled in the art. Conventional means is provided for rotating the drill steel as it is percussively actuated by the hammer piston, comprising a ratchet and pawl mechanism I3 having a spirally grooved rifle bar I4 slidingly interlocked with a rifle nut I5 secured within the hammer piston. As rthe hammer piston moves forwardly, the pawls of the ratchet and pawl mechanism permit the rifle bar to rotate so that the hammer piston delivers an unimpeded blow to the shank of the drill steel, and upon vthe return movement of the `hammer piston, the rifle blar is held against rotation by the pawls, and, due to the spiral groove connection between the rie .bar and piston, the piston is caused to rotate.. The rotary motion ,of the piston is transmitted to the drill steel through straight flutes I6 formed longitudinally.

on the piston striking bar and slidingly interl locked with straight lugs I'I formed ona chuck nut I8 secured Withina chuck sleeve I9. AThis chuck sleeve is rotatably mounted Within a front chuck housing 20 and has secured thereto a chuck bushing 2| in which the shank of the drill y50 steel I0 is mounted. It will thus be seen that as the hammer piston reciprocates to actuate percussively the drill steel, the latter is atY the same time intermittently rotated.

Now referring to the improved hole cleansing means for admitting only liquid to the bottom of the drill hole, it will be noted that secured, as by a gland plug 22, within the back head 23 of the motor cylinder is a liquid conducting tube 2li to which liquid under pressure is supplied through a pipe connection 25 from any suitable source Yof liquid supply. This liquid conducting tube extends axially through alined bores 2t and 2 formed in the rie bar and hammer piston respectively and at its forward end slidably ts an axial bore 28 formed in the drill steel i0. The forward end of the liquid conducting tube has a tight sliding t with the drill steel bore. In order to comply with certain regulations it may be desirable to terminate the liquid conducting tube 24 short of the lshank of the drill steel I0 instead of extending it therei-nto. In this illustrative construction the shank of the drill steel I has a reduced cylindrical portion 29 at its rear end, and this reduced shank portion is machined to have a tight sliding fit and is slidably guided in a wear and shank-centering washer or ring 30 supported within the chuck sleeve I9, this wear washer being mounted in the chuck sleeve bore and held between a shoulder provided by an inwardly directed ange 3i formed on the chuck sleeve and the rear end 0f the chuck bushing 2l in the manner shown in Figure 1. The chuck sleeve IS has formed therein a chamber 32 within which the rear end of the drill steel shank projects iri a position to receive the impact blows of the piston striking bar, and the latter is adapted to move, as the piston reciprocates, through the chuck sleeve and an alined bore 33 communicating with the chamber 32, into this chamber. In this improved construction, the chuck sleeve I9 is provided with an annular series of vent holes 3G each formed longitudinally through the body of the chuck sleeve and opening at their rear ends within the chamber 32 and at their front ends at the forward face of the chuck sleeve. Due to the vent holes 3d extending longitudinally within the body of the chuck sleeve I9, the external surface of the chuck sleeve presents a substantially unbroken surface which facilitates the lubrication thereof. There is provided near to and in front of the forward ends of the vent holes 34 an external ange 35, herein formed integral with the chuck bushing 2l, this flange having a curved deflecting surface 3S for laterally deilecting the air as it is vented from the chamber 32 through the vent holes 3d. It will thus be seen that any compressed air as it iiows from the bore of the motor cylinder through the flutes I E in the striking bar and through the chuck sleeve and the bore 33 to the chamber 32, is vented to atmosphere through the vent holes 3d so that the building up of any substantial air pressure at the rear end of the drill steel shank is prevented. The provision of the lateral deiiecting ange 35 prevents the blowing of compressed air through the longitudinal vent holes 34 toward the mouth of the drill hole, thereby further preventing the agitation of any rock dust which might be present at the mouth of the drill hole. If desired, by placing the flutes of the striking bar in alinement, more or less, with the vent holes 34 through the chuck sleeve, an aspirator effect is produced which results in the provision of an actual suction effect at the rear end of the drill steel shank for further insuring the prevention of passage of compressed air through the drill vantageously, the bore 33 is large in radial dimension as compared with standard practice, in order to insure adequate flow area; and the rear ends of the vent holes 34 may be sloped inward towards the axis so as to bring their rear orifices substantially into alinement with the flutes I6 in the sense that both are at about the same radial distance; the radius ofthe bore 33 being preferably not less than the radial distance of the rear orifices of the vent holes 34.

As a result of this invention, it will be noted that an improved rock drill hole cleansing means is provided wherein the admission of compressed air through the drill steel to the bottom of the drill hole is entirely eliminated, due to the improved venting arrangement of the chuck sleeve chamber at the rear end of the drill steel shank. It will further be noted that by the provision of the improved arrangement of the chuck venting means water under pressure is supplied to the drill hole to cleanse the cuttings from the hole while the entrance of compressed air to the drill hole is absolutely precluded. It will still further be evident that the improved hole cleansing means, due to its simple nature, may be readily applied to a conventional rock drill with a minimum of change and expense. Other advantages of the improved hole cleansing means 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 the invention 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 hole cleansing means, the combination with a rock drill having a chuck formed with a bore, and a chuck bushing mounted in said chuck bore for receiving and supporting the shank of a hollow drill steel, the chuck having a chamber within which the rear end of the drill steel shank projects in a position to receive the impact blows of the drill hammer piston and into which chamber pressure fluid flows from the motor cylinder of the drill past the piston striking bar as the hammer piston percussively actuates the drill steel, of means for venting said chamber to atmosphere to prevent the building up of a substantial pressure at the rear end of the drill steel shank, comprising a series of longitudinal vent passages formed in and extending lengthwise of said chuck externally of said chuck bushing, said Vent passages formed in the chuck between the walls of the chuck bore and the exterior surface of the chuck, said bent passages opening at their rear ends in said chamber and at their forward ends at the front end of the chuck.

2. In a rock drill hole cleansing means, the combination with a rock drill having a chuck formed with a bore, and a chuck bushing mounted in said chuck bore for receiving and supporting the shank of a hollow drill steel, the chuck having a chamber within which the rear end of the drill steel shank projects in a position to receive the impact blows of the drill hammer piston and into which chamber pressure iiuid flows from the motor cylinder of the drill past the piston striking bar as the hammer piston percussively actuates the drill steel, of means for venting said chamber to'atmosphere to prevent the building up of a substantial pressure at the rear end of the drill steel shank, comprising a series of longitudinal vent passages formed in said chuck externally of said chuck bushing, said vent passages extending length- Wise of the chuck and formed in the chuck between the Walls of the chuck bore and the eX- terior surface of the chuck, said Vent passages opening at their rear ends in said chamber and at their forward ends at the front end of the chuck, and means arranged at the front end of the drill steel chuck and against which the pressure fluid discharged from said vent passages impinges for deecting the pressure fluid discharged rom said Vent passages in a lateral direction With respect to the drill.

WILLIAM M. ALEXANDER.

CERTIFICATE 0E CORRECTIONu Patent No. 2,217,555., october 8, 191m.

wILLIAM M. ALEXANDER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line lO, for slidably" read --s1iding1y; and second column', line 60, claim l, for the Word "bent read "vent-g and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

signed and Sealed this 12th dey ef November, A.. D. I9LIO.

Henry7 Van Arsdale,

(Seal) Acting Commissioner of Patents.

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