US3918531A

US3918531A - Hydraulic rock drill having automatic carriage feed

Info

Publication number: US3918531A
Application number: US479208A
Authority: US
Inventors: Lester A Amtsberg
Original assignee: Chicago Pneumatic Tool Co LLC
Current assignee: Chicago Pneumatic Tool Co LLC
Priority date: 1974-06-14
Filing date: 1974-06-14
Publication date: 1975-11-11
Anticipated expiration: 1992-11-11

Abstract

An hydraulically operable rock drill having an hydraulically reciprocable power piston to which drill rod is attachable, the rock drill being mounted by means of a carriage upon a guide channel along which the carriage is caused to be automatically and hydraulically fed relative to the work, simultaneously moving with progression of the drill bit into the rock.

Description

United States Patent Amtsberg Nov. 11, 1975 4] HYDRAULIC ROCK DRILL HAVING 3.231176 2/1966 Henning et a1. 91/321 x AUTOMATIC C Ri GE D IlE/[dwargs 173/7593):

, onta ert Inventor: Lester s g, Utica, NY 3.459.401 8/1969 Weaver 91/39 x 3 6320.312 11/1971 Kransnoff.... 173/105 X [73] Ass'gnee' g i g'g T00] Cmnpany 3,701,386 10/1972 Feucht 173/78 6w 3 1 3,747,694 7/1973 Kollandsou'd 173/105 [22] Filed; June 14, 1974 3,785,248 1/1974 Bailey 173/105 X [21] A l N 479 208 3.8054896 4/1974 Bauer 91/39 X 0.: pp FOREIGN PATENTS OR APPLICATIONS 522,734 6/1940 United Kingdom 173/10 [52] us CL 173/10 4.033 10/1877 United Kingdom 173/10 51 1111.05 B23 5/34 Prmzar Emmmer-Ernest R. Purser [58] Fleld of Search 33 3; Assistant Eraminer-Leslie A. Braun Attorney, Agent, or Firm-Stephen J. Rudy [56] References Cited S AC UNITED STATES PATENTS [57] AB TR 336,401 2/1886 Fischer 173/153 5 1991991199111 Operable rofrk drlll hav ng anhydrau- 679999 8/190] Sergeant et a1 4 I n 91/40 X hcally reclprocable povl er p ston to wh1ch dr1ll rod is 1.430.764 10/1922 Smith 91/321 x attachable, the rock drlll bemg mounted y means of 1,718,430 6/1929 173/10 a carriage upon a guide channel along which the car- 1,733,402 10/1929 173/10 riage is caused to be automatically and hydraulically 1,797,445 3/1931 Runclqvist 173/10 fed relative to the work, simultaneously moving with gundqvlst 8 progression of the drill bit into the rock. ergmann 1 v 3,203,489 8/1965 Fuehrer 173/159 X 6 Claims, 5 Drawing Figures Sheet 2 0f 3 3,918,531

U..S. Patent Nov. 11, 1975 HYDRAULIC ROCK DRILL HAVING AUTOMATIC CARRIAGE FEED BACKGROUND OF THE INVENTION This invention relates to hydraulically operable rock drills of a type designed to be fed along a carriage relative to the work. And it is especially concerned with the provision of advantageous automatically operable feed mechanism for such tools.

While the invention is subject to wide application, it is especially suited for use in combination with a rock drill having an hydraulically reciprocable piston to which a drill string carrying the rock bit is attached. A tool of this nature is described in my co-pending application Ser. No. 468,899, filed May 10, 1974 entitled An Hydraulic Tool.

With each reciprocation or cycle of the piston in a tool of this kind, the rock bit is carried by the drill string through a work stroke and a return stroke. To obtain a high degree or optimum of operating effi- -ciency the too] should be advanced along the carriage with each cycle of the piston a distance substantially corresponding to the extent of penetration of the rock bit into the work. A skilful drill operator could provide a reasonable degree of controlled feeding in this respect by dexterous operation of manual feed controls and by use of suitable visual guide markings on the drill string. However, it would be of immeasurable benefit to be able to accomplish this in a more practical manner.

Accordingly, it is an object of this invention to provide practical and efficiently operating mechanism for effecting automatically hydraulic feeding of a rock drill relative to the work as needed with each cycle of the piston.

It is a further object of this invention to arrange this feeding mechanism in such manner that the hydraulic fluid which is actuating the piston on a work stroke will automatically be caused to also operate the feed mechanism.

In accordance with the invention, there is provided a rock drill tool comprising a piston cylinder, a power piston hydraulically reciprocable in the cylinder having a piston rod adapted for attachment of drill rod thereto, a source of pressurized hydraulic fluid, a control valve connected between the source and the cylinder for causing application to the cylinder of fluid from the source to drive the piston on a power stroke, a guide channel, a carriage mounting the tool for sliding movement along the guide channel, hydraulically operable carriage feed means connected to the carriage for feeding the carriage along the channel, and port means conmeeting the cylinder with the carriage feed means effective following a predetermined extent of relative movement of the piston on a power stroke to port pressurized fluid from the cylinder to operate the carriage feed means.

BRIEF DESCRIPTION OF THE DRAWING FIG. 5 is a schematic view of the tool as associated with the carriage feed mechanism.

DESCRIPTION OF PREFERRED EMBODIMENT The rock drill illustrating the invention includes a general housing 10 having a bore 11 opening through opposite ends of the housing, in which bore a piston cylinder 12 is fitted. A piston 13 formed at the rear end of a piston rod 14 is hydraulically reciprocable in the cylinder. The piston rod has. an externally projecting end 15 to which is attached a drill string 16 carrying at its bottom end a rock bit (not shown).

A rotation motor 17, operable independently of the operation of the piston, is arranged to transmit rotation through the piston rod to the drill string and rock bit during drilling operations. The motor is mounted to the rear of the housing. It has an extended output drive shaft 18 having a splined driving connection 19 with the piston whereby rotation of the motor is transmitted to the piston and to the attached drill string. The splined connection 19 is defined by internal splines of a recessed rear end of the piston slidably engaging a complementary splined surface of the drive shaft 18, whereby the piston is axially slidable relative to the shaft.

The piston has an annular front end area 22 which is subject to pressure of hydraulic fluid from a bulk oil accumulator or reservoir 23 to move the piston in a rearward or return stroke direction; and it has a rear end of relatively greater area defined by the annular end wall 24 and the recessed back 25, which area is subject to pressure fluid from the reservoir to move the piston in a forward power or work stroke direction.

The reservoir is in the form of an annular chamber extending about a core portion 26 of the housing. The core is located in the lower half of the housing in eccentric relation to the reservoir. The reservoir is constantly maintained pressurized with oil by a constantly operating variable pressure pumping system 27. A principal advantage of arranging the bulk reservoir in very close proximity to the piston is that it provides a large volume or bulk fluid source for reciprocating the piston. In this arrangement, the required flow passages from the reservoir to the piston cylinder are relatively shorter than would otherwise be, thus resulting in a conservation of fluid energy and in a compact structure with a reduced number of parts.

The reservoir connects directly by means of a port 28 through the cylinder 12 with an annular area 29 adjacent the front end 22 of the piston whereby the front end of the piston is constantly urged by pressure of the reservoir fluid in a return direction.

A control valve 31 (FIGS. 1-4) is operable to alternately expose the relatively greater rear area or driving end of the piston to the pressure of the reservoir fluid at a port 32 (FIG. 2) and to a pressure relief line 33 (FIGS. 3, 4) so as to effect reciprocation of the piston.

The control valve is reciprocable in a bushing 34 (FIGS. 34) fitted in a relatively longer bore 35 of the housing. The bushing has inlet ports 36 connected (FIG. 2) with the reservoir port 32; and has discharge ports 37 connected (FIG. 4) with the pressure relief line or sump conduit 33. The bushing also has common ports 38 connecting with an annular area 39 in the cylinder, to which area the rear and back surfaces of the piston are exposed, the back surface 25 being exposed to this area through ports 41 in a hollow portion of the drive shaft 18.

Ports 38 are common in that they are connectible by means of a peripheral groove 42 about the body of the valve with either the inlet ports 36 or the discharge ports 37, accordingly, as the control valve is reciprocated. In a first or pressure feed position of the valve (as in FIG. 3) groove 42 connects the inlet ports 36 through the common ports 38 with the area 39 rearwardly of the piston to effect movement of the piston on a work stroke. And in an opposite second or pressure relief position (as in FIG. 4) groove 42 connects the area 39 through the common ports 38 with the discharge ports 37 to effect a return stroke of the piston.

The control valve 31 is reciprocable from one position to the other relative to the inlet, and discharge ports by means of a rotary motor 20. The valve motor is driven by pressure oil continuously being fed to it from the reservoir through a flow regulating valve connected in a line between an outlet of the reservoir and an inlet to the motor. The rotation of the motor is translated into reciprocation of the control valve by means of a crank connection 50 of the output shaft of the motor with control valve 31. Oil spent in driving the motor returns to sump over a line 60. With each cycle of the motor, the control valve is reciprocable to cause the piston 13 to travel through a work stroke and a return stroke.

The frequency of piston reciprocation depends upon the regulated flow of reservoir fluid through the valve motor 20 and consequently upon the speed of the latter.

An optimum operation of the valve and consequently of the tool is obtained if the valve shifts from its FIG. 3 pressure position to its FIG. 4 discharge position at about the time when the piston impinges the rock bit end of the drill string against the work. This operating condition is obtainable by adjusting the linear position of the valve bushing 34 in the bore 35 and, as a consequence, the position of its inlet and

discharge ports

36, 37 relative to a center or mid-point stroke position of the valve.

When the valve obtains its FIG. 4 discharge condition, the inlet ports are blocked and pressure rearwardly of the piston is relieved through the discharge ports allowing the reservoir pressure at the front end 22 of the piston to then return the piston rearwardly.

During the return stroke, acceleration of the piston will prevail until the valve shifts from its FIG. 4 discharge condition to its FIG. 3 pressure condition. When this occurs, the discharge ports 37 are blocked and the inlet ports 36 are connected to feed reservoir pressure fluid from port 32 (FIG. 2) to the rear area of the piston. The resultant reversal of fluid forces causes deceleration of the piston to zero followed by acceleration of the piston on a power or work stroke.

The linear travel space for the piston is defined between an internal shoulder 43 of the cylinder and the stationary front end 44 of the drive shaft. This space is considerably greater than the amplitude of the piston so that during operation of the tool the piston normally will not bottom against either limit.

A principal feature of the tool is automatically operable feed means, as will now be described, for advancing the tool forwardly with the progress of the work.

The feed means (FIGS. 1, 5) includes a conventional stationary guide channel 45 upon which a feed carriage 46, fixed to the underside of the housing of the tool, is slidably mounted in usual manner for guided sliding movement relative to the work. Thrust for moving the carriage along the channel is provided by a feed piston 47 that is hydraulically operable in an hydraulic feed 7 It canbe seen that, as pressurized hydraulic fluid is applied over a hose line 54 to the feed cylinder 48 rearwardly ofthe feed piston 47, the latter will be moved in the cylinder to cause a corresponding advance or feed of the carriage 46 and the tool along the channel. This hydraulic fluid is caused to be fed from the reservoir 23 through the rear area 39 of the piston cylinder 12 and connecting passages to the hose line 54 during the power stroke of piston 13 in accordance with a predetermined extent of movement of the latter.

The passage connecting cylinder 12 with the feed hose line 54 includes an annular groove 55 formed about the inner face of cylinder 12, which groove connects through radial ports with a passage 58 extending through the. housing and connected with the hose line 54. A spring biased check valve 59 in passage 58 allows pressurized fluid flow from the power piston cylinder to the hose line only during the time that the internal groove 55 is uncovered by piston 13 and the control valve 31 is in its FIG. 3 condition feeding pressurized reservoir fluid to the rear area 39 of the piston 13..Dur-

hydraulically advanced along the guide channel 45 relative to the work.

As earlier explained, the shifting of the control valve 31 from one position to the other causes reciprocating movement of the power piston 13 and the attached rock bit away from and into the work. In the optimum adjusted condition of the valve bushing 34 relative to a center position of the control valve, as earlier explained, the control valve will shift from its FIG. 3 pressure condition to its discharge FIG. 4 position at about the time that the rock bit strikes the work. Accordingly, during an initial portion of the power stroke of the power piston 13, the latter will be moving forwardly toward the work while still covering over the annular groove 55 and normally shortly before the control valve shifts to the discharge position will commence to uncover the annular groove 55 as the rock bit strikes the rock work. Hydraulic feeding of the tool along the guide channel by the feed cylinder 48 will then occur until the control valve has reshifted and pressurized reservoir fluid flow to the rear of the piston 13 has ceased. On the return stroke of the piston, the annular groove 55 is recovered by the piston. The check valve 59 prevents back flow from the feed cylinder to cylinder 12. As can be seen, the tool will, in effect, be feed ing forwardly concurrently with the advance of the rock bit into the work.

A conventional manually operable control or main valve (not shown) connected with a source of pressurized fluid together with appropriate hydraulic hose lines to the rear and forward ends of the feed cylinder 48 is operable in conventional manner to properly locate carriage 46 along the guide channel 45 relative to the work at the start of operations and, when needed, to retract the carriage along the channel to add further lengths of drill rod to the drill string. It is understandable by those knowledgeable in this art that when the feed piston 47 has been advanced to its maximum position, the manually operable control valve (not shown) may be actuated as needed to relieve the pressurized condition in the feed cylinder 48 from the rear of the feed piston to permit retraction of the carriage and the addition of an added length of rod to the drill string.

While the invention has been illustrated and described in detail herein, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts thereof without departing from the spirit and scope of the invention. Accordingly, it is my intent to claim the invention not only as shown and described herein, but also in all such forms and modifications as may reasonably be construed to fall within the spirit of the invention and the scope of the appended claims.

Iclaim:

1. An hydraulic rock drill tool comprising a piston cylinder, a power piston hydraulically reciprocable in the cylinder having a piston rod with a drill string attached thereto for reciprocation of the drill string and piston as a unit, a source of pressurized hydraulic fluid, the piston having a forward end surface area subject to application of pressurized fluid from the source to move the piston on a return stroke and having an opposite rear end relatively greater surface area subject to application of pressurized fluid from the source to move the piston on a power stroke, first port means constantly exposing the forward end surface area of the piston to pressurized fluid from the source, power driven control valve means operating independently of the operation of the piston for exposing the relatively greater rear end surface area of the piston at the rear of the cylinder alternately to pressurized fluid from the source and to a discharge passage, a guide channel, carriage means mounting the tool for sliding movement along the guide channel relative to the work, hydraulically operable carriage feed means connected to the carriage means for feeding the latter along the channel, and second port means connecting the cylinder at the rear of the latter with the carriage feed means effective following an initial predetermined extent of movement of the piston on a power stroke from a return position to divert some of the pressurized fluid from the rear of the cylinder to operate the carriage feed means concurrently as pressurized fluid at the rear of the cylinder is acting on the rear end surface area of the piston.

2. An hydraulic rock drill comprising a main cylinder, a main piston hydraulically reciprocable in the cylinder having a piston rod and a drill string attached to the latter for reciprocation as a unit with the piston, a source of hydraulic pressurized fluid, the piston having a forward end surface area exposed constantly through a port to pressure fluid from the source urging the piston to a return position and having an opposite rear end of relatively greater surface area adapted upon application of pressure fluid from the source to a rear area of the cylinder to move the piston on a work stroke, a power driven reciprocable valve for exposing the rear area of the cylinder alternately to the source of pressurized fluid and to a discharge passage, the valve having a peripheral groove adapted upon movement of the valve in one direction to communicate the source of pressurized fluid with the rear area of the cylinder and adapted upon movement of the valve in an opposite direction to communicate said rear area of the cylinder with the discharge passage, and a motor separate from and operable independently of the operation of the piston having a driving connection with the valve for reciprocating it from said one position to the other; wherein the rock drill has a carriage mounted upon a guide channel for movement relative to the work, an hydraulically operable feed piston connected to the carriage for advancing the carriage along the channel with the progress of the work is operable in a feed cylinder fixed to the channel, a hose line connects an area in the feed cylinder rearwardly of the feed piston with an outlet port from a rear area of the main cylinder, the main piston covers over the outlet port in its returned position, and the main piston is adapted following a predetermined extent of initial movement on a work stroke from its returned position to uncover the outlet port so as to allow some of the pressurized fluid being applied to the rear area of the main cylinder to pass through the outlet port over the hoseline to the feed cylinder to advance the feed piston and as a consequence advance the rock drill along the carriage concurrently with movement of the main piston beyond the outlet port.

3. An hydraulic rock drill comprising a main cylinder, a main piston hydraulically reciprocable in the cylinder having a piston rod carrying a drill string for reciprocation of the drill string as a unit with the piston; a common source of hydraulic pressurized fluid; the piston having a forward surface area exposed constantly through a port to the pressurized fluid urging the piston to a return position, the piston having a relatively greater rear surface area subject to application of the pressurized fluid to move the piston from its returned position forwardly on a work stroke; a control valve for exposing the rear surface area of the piston alternately to application to it of the pressurized fluid and to a discharge passage so as to effect reciprocation of the piston, the control valve being reciprocable between a position exposing the rear surface area of the piston to the pressurized fluid and a reverse position exposing said rear surface area to the discharge passage; a motor separate from and operable independently of the operation of the piston drivingly connected to the control valve to reciprocate the latter from said one position to the other; a guide channel; a carriage mounting the rock drill for sliding movement along the channel relative to the work; and carriage feed means for feeding the carriage along the channel toward the work following a predetermined initial forward movement of the piston from its returned position toward the work, the feed means comprising an hydraulic feed cylinder, a feed piston hydraulically operable in the feed cylinder having an externally projecting rod connected to the carriage, a hose line connecting an area of the feed cylinder rearwardly of the feed piston with an outlet port opening out of a rear area of the main cylinder, the outlet port being covered over by the main piston in a returned position of the latter and adapted to be uncovered by the main piston after a predetermined initial forward movement of the main piston on a work stroke from its returned position so as to permit escape through the hose line to the rear area of the feed piston cylinder of some of the pressurized fluid being applied to the rear surface area of the main piston and thereby actuate the feed piston to effect forward feeding of the carriage along the channel concurrently with further forward movement of the main piston beyond said outlet port.

4. An hydraulic rock drill as in claim 3, including a check valve in the hose line normally blocking backflow of pressurized fluid from the rear area of the feed cylinder over the hose line and through the said outlet port into the main cylinder.

5. An hydraulic rock drill as in claim 3, wherein the control valve is connected between an outlet port of the source and the rear area of the main cylinder and between the said latter area and the discharge passage. 6. An hydraulic rock drill as in claim 5, wherein the control valve has a first position blocking communication of the outlet port of the source with the rear area of the main cylinder and communicating the said latter area with the discharge passagej and has a reverse position communicating the said rear area of the main cylinder with the outlet port of the source and blocking communication of said rear area of the main cylinder with the discharge passage.

Claims

4. An hydraulic rock drill as in claim 3, including a check valve in the hose line normally blocking back-flow of pressurized fluid from the rear area of the feed cylinder over the hose line and through the said outlet port into the main cylinder.

5. An hydraulic rock drill as in claim 3, wherein the control valve is connected between an outlet port of the source and the rear area of the main cylinder and between the said latter area and the discharge passage.

6. An hydraulic rock drill as in claim 5, wherein the control valve has a first position blocking communication of the outlet port of the source with the rear area of the main cylinder and communicating the said latter area with the discharge passage; and has a reverse position communicating the said rear area of the main cylinder with the outlet port of the source and blocking communication of said rear area of the main cylinder with the discharge passage.