Title:
Controlling device for rock drills
United States Patent 2255231


Abstract:
This invention relates to rock drills, and more particularly to a controlling device for the feeding mechanism of a rock drill. One object of the invention is to maintain a uniform feeding pressure in the feeding mechanism. Another object is to automatically control the flow of pressure fluid...



Inventors:
Slater, Fred M.
Application Number:
US29798039A
Publication Date:
09/09/1941
Filing Date:
10/05/1939
Assignee:
INGERSOLL RAND CO
Primary Class:
Other Classes:
24/115R, 137/505.38, 137/538, 137/625.39
International Classes:
E21B19/086
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Description:

This invention relates to rock drills, and more particularly to a controlling device for the feeding mechanism of a rock drill.

One object of the invention is to maintain a uniform feeding pressure in the feeding mechanism.

Another object is to automatically control the flow of pressure fluid to and from the feeding mechanism.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specification and in which similar reference numerals refer to similar parts, Figure 1 is a longitudinal view, partly broken away, of a rock drilling mechanism equipped with a controlling device constructed in accordance with the practice of the invention, Figure 2 is a transverse view taken through Figure 1 on the line 2-2, Figure 3 is an elevation, partly in section, of a detail, and Figure 4 is a perspective view of a detail.

Referring more particularly to the drawing, 20 designates a rock drill and 21 a feeding mechanism for actuating the rock drill relatively to the work, illustrated as rock 22.

The rock drill 20 may be of a well known fluid actuated percussive type having a reciprocatory hammer piston 23 for actuating a drill steel 24 into the rock 22. The pressure fluid utilized for actuating the hammer piston 23 may be distributed thereto by a suitable valve mechanism (not shown) and the admission of pressure fluid into the rock drill is controlled by a throttle valve 25 having a suitable lever for rotating it.

The feeding mechanism 21, which is also actuated by pressure fluid, comprises a cylinder 26 that supports the rock drill 20. The cylinder 26 is accordingly provided on its periphery with guide ribs 27 that extend into guideways 28 of a bracket 29 clamped to the rock drill by the side rods 30 which hold the casing parts of the rock drill together. The cylinder 26 contains a piston 31 having a rod 32 that extends through the front end of the cylinder 26 and is attached to a bracket 33 carried by the rock drill.

The rod 32 has a tapered stem 34 which extends through the bracket 33 and has a nut 35 threaded thereon to seat against the bracket for drawing the stem 34 into tight frictional engagement with the bracket 33, and on the front end of the rock drill is a lug 36 through which extend bolts 31 that are threaded into the bracket 33 to secure the said bracket to the rock drill.

The pressure fluid utilized for actuating the feeding mechanism 21 also passes through the throttle valve 25 which, accordingly, is provided with a port 38 in its wall to register with a supply passage 39 leading from the throttle valve through the back head 40 of the rock drill, a tube 41 threadedly connected to the back head and the front head 42, thence through the lug 36, the bracket 33 and through the rod 32 and opens into a pressure chamber 43 in the rearward end of the feeding cylinder 26.

In accordance with the practice of the invention the passage 39 is additionally controlled by valve mechanism adapted to operate in response to the pressure of the fluid within the feeding mechanism for maintaining a substantially uniform feeding pressure. The valve mechanism illustrated, by way of example, and designated in its entirety by 44 is disposed in the back head 40 which accordingly has a bore 45 bisecting the supply passage 39 to receive the valve mechanism 44. In the lower part of the bore 45 is a bushing 46 having a bore 41 to slidably receive the valve 48 which controls communication between the adjacent branches of the passage 39, and at the upper end of the bushing encircling the bore 41 is a bevelled seat 49 which cooperates with a correspondingly formed surface 50 on the valve to normally seal the bore 41.

In the periphery of the bushing 46 is an annular groove 51 which communicates with the branch of the passage 39 leading to the throttle valve 25, and ports 52 in the bushing 46 afford communication between the groove 51 and a groove 53 in the inner surface of the bushing 46.

The pressure fluid thus entering the groove 53 passes through the valve 48 which accordingly has a recess 54 opening into the lower end of the bore 45, and in the wall of the valve 48 are ports 55 to communicate the recess 54 with the groove 53.

The ports 55, of which four are shown in the drawing, lie in different transverse planes but are so arranged with respect to each other that when the valve occupies a position in which the surfaces 49 and 60 are in engagement with each other all of the ports 55 will be in communication with the groove 53.

50 The recess 54 extends to a point near the upper end of the valve and adjacent the upper end of the recess, and in the wall of the valve 48, are discharge ports 56 which also lie in different transverse planes and are so positioned that when the valve is seated upon the end of the bushing 46 all of said discharge ports will be sealed by the inner surface of the bushing.

In order that the valve may move responsively to the pressure value in the feeding mechanism the inner end of the valve 48, constituting a pressure surface 57, is constantly exposed to pressure fluid and on the rearward end of the valve is a spring 58 which opposes the pressure fluid acting against the pressure surface 57 and tends to hold the valve in a position to seal the discharge ports 56 and to maintain all of the ports 55 in communication with the groove 53. The spring 58 is adjustable, being seated against a hollow plug 59 threaded into a sleeve 60 which abuts the bushing 46 to hold said bushing firmly in position. Suitable means are provided for preventing unauthorized rotary movement of the plug 59.

To this end a plate 61 is disposed slidably upon a reduced stem 62 of the plug, and on the plate 61 and on the sides of the stem 62 are flatted surfaces 63 and 64, respectively, which slidably engage each other to prevent rotary movement of the plate with respect to the stem. On the inner surface of the plate 61 are lugs 65 to seat into depressions 66 in the outer end of the sleeve 60 to lock the plate 61 to the sleeve.

The plug 59 may be conveniently rotated by a knob 67 attached to the outer end of the stem 62, and within the knob 67 is a spring 68 that bears against the outer end of the plate 61 to press it against the sleeve 60.

As a preferred arrangement, the feeding cylinder 26 is provided with means for manually relieving the pressure therein. To this end an qxhaust passage 69 is formed in the rearward end of the feeding cylinder and communication between said passage 69 and the pressure chamber 43 is controlled by a spring pressed poppet valve 70 having a stem 71 that extends exteriorly of the cylinder so that it may be conveniently engaged for unseating the valve 70.

In practice, whenever it is intended to operate the drilling mechanism the throttle valve 25 is positioned to admit pressure fluid to the rock drill 20. In this position of the throttle valve pressure fluid also flows through the supply passage 39 and the valve 48 into the pressure chamber 43 to act against the piston 31 for moving the rock drill along the feeding cylinder 26. Thus, during the subsequent operation of the rock drill the pressure fluid acting against the piston 31 will advance the rock drill in accordance with the penetration of the working implement 24 into the rock 22. If the value of the pressure fluid acting against the piston 31 is such that the required feeding pressure may be maintained against the piston 31 all of the ports 55 will be in communication with the groove 53 and a full supply of pressure fluid will, therefore, be admitted into the pressure chamber 43. In the event, however, that the supply pressure increases above that which it is intended to maintain in the pressure chamber 43 the pressure acting against the surface 57 of the gg valve will raise the valve and move the uppermost of the ports 55 out of communication with the groove 53.

In this way the flow of pressure fluid to the pressure chamber 43 is partially cut off, and if the pressure value at supply continues to increase the valve 48 will be shifted upwardly and thus blank off another port or ports 55 to further reduce the flow of pressure fluid into the feeding cylinder. This movement of the valve may continue until only the lowermost of the ports 55 remains in communication with the groove 53, and if the value of the pressure fluid continues to increase the uppermost discharge port 56 will be raised above the bushing 46. Pressure fluid will then be exhausted from the pressure chamber 43 through a discharge port, or ports, 56 and will flow through the plug 59 and the knob 67 to the atmosphere.

After the pressure within the pressure chamber 43 has been reduced to the correct value the spring 58 will move the valve downwardly to effect a larger area of communication between the groove 53 and the recess 54 and to again blank off the discharge ports 56. These movements of the valve 48 will take place whenever the pressure in the feeding cylinder predominates over the pressure exerted by the spring 58, and when the feeding pressure is normal, or below normal, the valve 48 will remain seated upon the bushing 46. A maximum area of communication will then be established between the pressure chamber 43 and the pressure fluid supply.

In the event that drilling conditions require a higher or lower feeding pressure the plug 59 may be rotated to vary the tension of the spring 58, and a higher or a lower pressure will then be required on the pressure surface 57 to actuate the valve 48 for effecting uniformity of pressure in the feeding cylinder.

Whenever it is desired to retract the rock drill, as after a run of drilling, the poppet valve 10 is unseated. Pressure fluid may then escape from the pressure chamber 43 to the atmosphere and the rock drill may be pulled rearwardly to its starting position by the operator.

As will be readily appreciated, by effecting the automatic control of the pressure within the feeding cylinder with a valve constructed in accordance with the practice of the invention the feeding pressure may be maintained at a practical value even though the supply pressure is of a higher value. This is desirable in devices of this character, particularly when drilling certain types of rock in which best results are obtained by applying maximum power to the percussive element of the drilling mechanism while feeding the drilling mechanism toward the work at a moderate pressure.

I claim: 1. A controlling device, comprising a casing having a supply passage for pressure fluid, a chamber in the passage, a valve in the chamber to control the passage and having a pressure surface subjected to the pressure fluid in the chamber and one branch of the passage for actuating the valve to reduce the admission of pressure fluid into the chamber, a recess in the valve in constant communication with said branch, and ports in the valve opening into the recess and being arranged in different transverse planes to move successively into and out of communication with the other branch of the passage to control the flow of pressure fluid into the chamber in accordance with the movements of the valve responsively to the fluctuations in the pressure of the fluid acting against the pressure surface.

2. A controlling device, comprising a casing having a supply passage for pressure fluid, a chamber in the passage, a valve m the chamber to control the passage and having a pressure surface subjected to the pressure fluid in one branch of the passage for actuating the valve, a plurality of groups of ports in the valve and the ports of one group being arranged to move successively into and out of communication with the other branch of the passage and the ports of the other group being arranged to move successively into and out of communication with the atmosphere to increase and decrease the flow area between the chamber and the atmosphere in accordance with the movement of the valve responsively to the fluctuations in the pressure of the fluid acting against the pressure surface, and a spring acting against the valve to oppose the force of the pressure fluid acting against the pressure surface.

FRED M. SLATER.