US1804066A - Pneumatic rock drill - Google Patents

Description

Patented May 5, 1931 i i PATENT or-Fica y arrogant SMITH, or ivronnsro, CALIFORNIA PNEUMATIC Roc-K DRILL Application med August 14, 1924. serial No. 732,123.

This invention relates to pneumatic Ydrills and hammers in general and more particularly to a rock drill in which t-he drilling is accomplished by successive blows upon the drill steel and the steel is also given a rotary motion between striking impacts against the rock. Y

T he principal objects of my improvements are to overcome some of the well known faults of prior drills of this class in providing:

A-Automatic means for instantly reducing rthe force of the blow upon the tool upon entering soft earth or a pocket inthe rock, thus avoiding destructive blows against the parts when not opposed bythe resistance of the rock.

vB--A manual or automatic control for reducing the force of the working blow with- 90 out affecting other operations of the mechanism. n

C A simplified rotating drive for giving the drill steel a fractional turn, operative upon either stroke of the piston.

D-A manual-control to stop the rotation without affecting the drilling operations.

EvAn improved arrangement for blowing out the drill hole throughv the water line.

F-An improved method of packing the water tube Within the anvil block.

'30 G-An yimproved method of packing the Vanvil housing. y

H-An improved piston construction whereby various weights of piston may be n used as the work may require, yet without affecting the cut-off relation of the parts.

I-Minor constructional improvements which will appear as the description proceeds.

Y I attain the objects mentioned by the pneumatic drill construction shown in the accompanying drawings and in which Figure 1 is alongitudinal section through the operating mechanism showing all of the important fea tures, and Figure 2 is a cross Section of Figure l taken along the line 2 2. Flgure 3 shows in enlarged section my special ring` packing. Figurei isa sectional view of avalve employed in my device showing its relation to certain passageways. f Before entering a detailed description of the mechanism, attention is called to the fact that the assemblage consists essentially of a main cylinder in the axial line of the drill steel or tool having the usual reciprocating piston or hammer within it for delivering successive blows to the tool, and of a plurality of other cylinders, with pistons or valves therein for controlling the .operation of the mechanism and also for rotatingthe tool.

These auxiliary cylinders and valves are Y in practice positioned around the main cylinder in a way to facilitate construction and assemblage of the mechanism, also to provide for the most direct running 'of the various passages and for coring them in the solid metal of the body to avoid exposed piping as much as possible. Y

In the drawing, however, the relation of the parts mentioned has been altered, the proportions of the walls changed, also the run of ports, so as to bring the various features into one comprehensive cooperating assemblage and avoid reference tov many sectional views in additional drawings. Y i f In the figures, (l) is the body of the machine comprising several sections all held together-by the usual clamping bolts extending through suitable flanges (2) and engaging the head Within the body is the main cylinder (4) with a reciprocating piston (5) therein` i Y l Axially extending from the body is the drill steel or tool (6) which may be lugged as shown at (7) or not. Y

The tool ishere shown as having a hollow shank aligned over a. water tube (8) extending from the head through the piston andi passing through an anvil block (9) which is slidable on the tube and which block is slidable Wit-hin the anvil housing (10). Y

The tube is packed within the anvil block by means of a special silk ring packing (11) forced through the tapered recess (l2) to-a slightly enlargedl recess (13), but the piston is slidable on the tube without any packing.-

'Ihe anvil has a shoulder (14)` lto limit its inward'sliding and in operation of the. drill is held vtightly against this shoulder by the endwise pressure of the tool which rests upon it as shown. This anvil also functions as an automatic valve to prevent a blow being dclivered to the tool if the latter finds no resistance aga-inst the rock on account of penetrating a pocket therein or of entering soft earth, for in either case the pressure of the tool upon the anvil is reduced whereupon the anvil is forced outward by the operating air and trips a premature exhaust on the striking blow as will later be described.

The main piston or hammer (5) is a plain steel cylinder adapted to cover and uncover the air ports for automatic reciproca-tion and has a central chamber filled with wood (15) or lighter metal so as to provide for interchange of similar length pistons with larger or smaller wool lilled chambers (15') and whereby the weight of tl e piston can be suit ed to the work with out altering the relation of the air ports to the pistons length. The Wood filler has also been found a valuable oil retainer to insure permanent lubrication of the water tube (8).

The reciprocation of the piston (5) is controlled by the distributing valve which alternatelyT admits air under pressure from the main inlet port (16) to the ports (17) and (18) extending respectivelyT to opposite ends of the piston, and which ports alternately act as exhausts for their respective ends by communicating through the recessed valve with a common exhaust port (19).

It should be here noted that the various` air passages are cored in the metal of the body and unless shown as connecing at intersecting points they are in different planes so as to pass each other and lead to their various destinations without interference.

The valve (.15) is itself tripped back and forth by the uncovering by the piston of small ports (20) and (21) which convey some of the active pressure fluid to the ends of the valve somewhat before the end of the stroke of the hammer piston in either direction.

Upon the inward or return stroke of the piston (5) the air reacts against the anvil housing (10) as well as the end of the anvil block (9) held back by the drill tool through pressure of the tool end against the rock being drilled, but in case of striking pocket .initherocln orif for any other reason the pressure of the tool against the anvil is rel lieved, the anvil is at once forced outwardv by the air pressure acting against its inner end, carrying the tool with 1t and bringing the by pass duct into registry with the automatic hammer blow control valve passage (23) which results in instantly reducing the force of the blow of the hammer piston (5) so that it will not strike with fnllforce against an inoperative tool te batter its lugs or destroy the mechanism7 but will keep up a gentle blow in soft material.

This is accomplished by a small piston valve (24) normally forced away from the head (3) by a spring (25) to close oil an auxiliary reverse valve tripping port (26) which communicates with the valve tripping passage (21).

rlhis small valve (24) is displaced by active air pressure from the by pass through the passa-ge (27) upon relief of the tool pressure on the anvil and opens auxiliary reversing port (26) so that the force of the hammer blow of piston (5) is diminished at about the first third of its travel and this condition is maintained until the pressure on the drilling tool is restored.

A check valve (28) is placed in passage (27) and a slow leak at (29) to permit return of valve (24) upon reestablishing normal drilling conditions.

The shock of distributing valve (15) is broken largely through confined air by proper design of portareas and further 'by metal plates (30) backed by live rubber disks (31).

ln addition to the main cylinder exhausting alternately through its intake ports as eX- plained, an additional or final exhaust is provided at (32) uncovered at either end of complete stroke.

lVhen drilling in material not requiring the maximum blo v, the air pressure inlet (18) for the striking blow may be independently throttled to any predetermined degree by means of a thumb control button actu ating spring released plunger (34) which closes olf the inlet passage (18) to an amountdepending on the threaded adjustment of the plunger with respect to the button which adjustment is permitted by the slotted end of the threaded member as shown at (35), thus by a simple pressure of th-e thumb the force of the blow is instantly reduced.

rlhe water tube receives its supply through the passage (36) from hose (37) controlled by valve (38) and the drill may be blown with air by a simple pressure of thumb piece (39) which moves the spring returned plunger valve (40) and opens the by pass duct (41) to the main air inlet (16) so that the air can pass directly to the water tube. The main air hose is indicated at (42) with main valve at (e3).

VEhe wat-er tube 8) is sea-led in the head (3) and ported to passage by suitable packing and glands in any suitable manner a s indicated.

Intermittent partial rotation of the drill tool is effected through means of a ratchet and pawl arrangement similar to the one described in my former Patent No. 1,284,804, with the exception that the reciprocating wedge (44;) is operated by an air piston (115) which is thrown outward at each inward movement of the main piston (5)- by air received at the same time through a passage (e6) connecting vith air inlet (17). Gr if desired the rotation may be effected at the outward stroke of the piston by throwing the two way valve (69) return eected by spring (50) surrounding the piston rod (5l) and reacting against the body (1). At the return stroke the air exhausts to the main cylinder through port (52) uncovered by the main piston (5) at the end n of its inward travel and thence through the passages (17) and (32), and the air above the piston escapes to a certain extent through the joints around the Wedge operating mechanisni thereby diffusing oil throughout, While the remainder is entrapped as a cushion until scavenged by uncovering of port (53) by the main piston (5).

The piston (45) is also filled With a block of Wood (45') so that it may still have length and area yet be light in Weight.

Rotary movement is transmitted to the tool (6) through its lugs (7) engaging slots (54) in retaining nut (55) screwed into the revolvable ratchet hub (56) having ratchet teeth (57) engaged by paivl (58) pivoted to sliding paWl block (59) and forced toward the teeth by springs (60), the paWl block being moved by the piston Wedge (44) to advance the paivl block against spring (6l) at each .stroke of the piston (45) substantially as described in my former patent inentione-d.

To avoid displacement or binding of piston rod (5l) through Wear of the Wedge (44) or block (59) a locking though sliding joint (62) is provided to connect the piston rod to the Wedge.

By the arrangement shown it Will be seen that the rotation of the tool takes place only before the blow of piston (5) and that the tool is stationary at the moment of the blow of the piston.

At any time that it is desired to drill With out rotation of the tool, a pressure of the finger on the push button (63) projects the end of it Within the cylinder (49) and stops the piston. t should be observed that this button (63) is at a portion of the cylinder circumference to avoid cut off slot (46).

In operation should the tool break through and allow the anvil to move forward upon the impact of piston (5), the bloW is arrested by a steel ring (64) supported against one of my special silk packing rings (65) A similar packing' ringis placed at (66) to seal the anvil housing (l0) against the revolvable ratchet hub (56). This packing Was devised especially for this purpose Where a seal must be maintained and the material must not compress and become dead when subjected to the force of an occasional Wild blow` When the tool breaks through.

Figure 3 is an enlarged section of the pack ing rings and shows them as made of silk threads Wound around (on a mandrel) in layers slightly crossing one another as shown at (67) to form a ring, then Winding or sewing other silk threads through the opening of the ring and over the outer sides as shown at (68) to tie them all together.` These special silk rings are soaked in oil before placing in position in the machine, ring (13) being forced into place With a special tool.

Having thus described in detail my improved rock drill it Will be seen to possess valuable features useful also in similar tools such as air hammersand the like, especially the automatic reduction of the striking blow upon reducing endvvise pressure of the tool upon the work, and While I show this accomplished by displacement of an anvil block whereby Vthe reversing valve is prematurely tripped by air pressure, it is manifest that this may be carried out by quite a number of artifices and any arrangement Which will produce this result falling within the spirit of my, invention is sought to be covered in my appended claims.

I claim: i

l. In a pneumatic rock drill, a cylinder, a piston movable therein, means forautomatically admitting fluid under pressure into the ends of said cylinder for reciprocating the piston, auxiliary means for reversing the movement of the piston when the latter has covered only a portion of its stroke, and tool controlled means for making operative said auxiliary means upon excessive outward movement of the tool.

2. In a pneumatic rock drill, a cylinder, a piston movabletherein, means for automatically admitting luid under pressure into the ends of said cylinder for reciprocating the piston, auxiliary iiuid operated means for reversing the movement of the piston when the latter has covered only a portion of its stroke, av tool, and tool controlled means for making operative said auxiliary means upon excessive outward movement of the tool, said L tool controlled means comprising an anvil block movably disposed between the piston and the tool and having a fluid passageway placing the fluid in the cylinder in communication ivith the piston reversing means when the anvil is moved to a predetermined position. Y

3. In a pneumatic rock drill, a cylinder, a piston movable therein, means for automatically admitting iiuid under pressure into the ends of said cylinder for reciprocating the piston, auxiliary means for reversing the movement of the piston when the latter has covered only a portion of its stroke, and tool controlled means for making operative said auxiliary means upon excessive outward movement of the tool, said auxiliary means comprising an auxiliary valve actuated when the tool controlled means is actuated, said auxiliary valve when actuated causing said first named means to cut off the fluid to the piston on its power stroke during the initial movement ot' the piston Jfor diminishingr the force oi' its blow.

4. A pneumatic rock drill comprising a cylinder, a piston movable therein, said cylinder having fluid passages for admitting fluid under pressure for reciprocating` the piston, a valve for alternately admitting; fluid to the ends ot' the cylinder, an auxiliary valve for admitting Huid to the {ii-st valve for actuating it after the piston has covered only a portion of its strolm said irst valve. when thus actuated admitting' fluid to the piston for reversing;` its movement, whereby the piston will delivei1 a light stroke to a tool.

5. A pneumatic rock drill comprising' a cylinder, a piston movable therein, said cylinder having iuid passages for admitting; fluid under pressure for reciproating; the pistonv` a valve for alternately admitting fluid to the ends of the cylinder, an auxiliary valve for admitting fluid to the first valve 'for actuating it after the piston has covered only a portion or' its stroke, said first valve when thus actuated admitting fluid to the piston 'for reversing` its movement, whereby the piston will deliver' a light stroke to a tool, and tool controlled means for operating said auxiliary valve.

MICHAEL SMITH.

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