TELESCOPIC ROCK DRILL FEED
United States Patent 3807510
A rock drill feed mechanism in which a drill motor is reversibly driven along a guideway by a rotatable power screw. The guideway is slidably mounted on an elongated support for reversible movement therealong by a second power screw mounted on the guideway. The power screws are driven independently by fluid motors and may be selectively controlled to operate the feed mechanism in a telescoped condition for movement of the drill motor alone or movement of the drill motor and the guideway to extend the useful feed length. A control circuit includes sensing devices for determining when the feed mechanism is fully telescoped or fully extended for reversing and shutting off the drill motor, respectively.
US Patent References:
Automated rock drill positioning support
Jonsson - March 1967 - 3307637
FEED MECHANISM FOR ROCK DRILL HOSE GUIDE
Rudman - March 1970 - 3500941
CABLE CYLINDERS
Wills - August 1972 - 3684035
Automated rock drill positioning support
Jonsson - March 1967 - 3307637
FEED MECHANISM FOR ROCK DRILL HOSE GUIDE
Rudman - March 1970 - 3500941
CABLE CYLINDERS
Wills - August 1972 - 3684035
Inventors:
Boom, Clarence O. (Littleton, CO)
Hanson, Laurence B. (Pine, CO)
Hanson, Laurence B. (Pine, CO)
Application Number:
05/315055
Publication Date:
04/30/1974
Filing Date:
12/14/1972
View Patent Images:
Export Citation:
Assignee:
Gardner-Denver Company (Quincy, IL)
Primary Class:
Other Classes:
408/129, 74/841
International Classes:
E21B19/081; E21B44/06; E21B19/00; E21B44/00; E21C5/02
Field of Search:
173/145,146,160,44,147,43 74/841 408/129,137
Primary Examiner:
Purser, Ernest R.
Attorney, Agent or Firm:
Martin M. E.
Claims:
What is claimed is
1. A rock drill feed mechanism for mounting on the distal end of a drill boom or the like and comprising:
2. The invention set forth in claim 1 wherein:
3. The invention set forth in claim 2 wherein:
4. The invention set forth in claim 3 wherein:
5. The invention set forth in claim 4 wherein:
6. The invention set forth in claim 5 together with:
1. A rock drill feed mechanism for mounting on the distal end of a drill boom or the like and comprising:
2. The invention set forth in claim 1 wherein:
3. The invention set forth in claim 2 wherein:
4. The invention set forth in claim 3 wherein:
5. The invention set forth in claim 4 wherein:
6. The invention set forth in claim 5 together with:
Description:
BACKGROUND OF THE INVENTION
Elongated supports or guideways on which a rock drill motor is reversibly moved therealong by a power screw are well known and advantageously used in underground drilling because of their relative light weight and ease of mounting on movable booms. In many tunneling operations it is desirable to provide a drill feed mechanism which will permit drilling relatively long holes in one pass of the drill along the feed support which support may also be telescoped or reduced in length to provide for drilling where space limitations in the tunnel will allow only comparatively short feed mechanisms to be positioned. Various arrangements of telescopic fluid cylinder and piston feed devices have been used to meet the requirements of the abovementioned operating conditions without providing the advantages of light weight and reliability enjoyed by power screw type feed mechanisms.
SUMMARY OF THE INVENTION
The present invention provides a telescopic feed mechanism for rock drills which may be extended to provide a relatively long feed length where working conditions permit and which may be telescoped to reduce the length of the feed mechanism for operation in restricted work spaces.
The present invention also provides a telescopic feed mechanism for rock drills which is of the lightweight power screw type which may be mounted on the distal end of a movable boom structure for maneuvering into positions where space limitations require the use of the feed mechanism in the telescoped condition.
The present invention further provides a telescopic feed mechanism in which dual power screws are driven independently by fluid motors which may be selectively operated to feed a drill motor along a guideway or to feed both a drill motor along a guideway while feeding the guideway along a support member. Moreover, the present invention contemplates a control circuit including position sensors operative to provide a signal when the drill motor and guideway have been fed forward or retracted to the limits of the feed mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal elevation partially sectioned of a telescopic feed mechanism in accordance with the present invention;
FIG. 2 is a transverse section taken along lines 2--2 of FIG. 1;
FIG. 3 is a partial longitudinal elevation of the feed mechanism of FIG. 1;
FIG. 4 is a transverse elevation of a mobile rock drill unit upon which the telescopic feed mechanism of FIG. 1 is mounted for operation in the telescoped condition;
FIG. 5 is a longitudinal elevation of the mobile rock drill unit shown in FIG. 4 with the telescopic feed shown in the extended position;
FIG. 6 is a schematic diagram of a control circuit for the telescopic feed mechanism of the present invention; and,
FIG. 7 is a schematic diagram of an alternate embodiment of a control circuit for the telescopic feed mechanism of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 through 3 the feed mechanism of the present invention is generally designated by the numeral 10 and includes an elongated support 12 adapted to be slidably retained by guides 13 which are mounted on a feed support 14. The feed support 14 is of a type which includes a pressure fluid cylinder and piston assembly 16 having the distal end of a piston rod 18 connected to the support 12 for moving the feed mechanism 10 with respect to the support 14 as shown by the positions of the feed mechanism in FIGS. 4 and 5. The feed support 14 is pivotally mounted on a positioner device 20 which in turn is mounted on the distal end of a movable boom 22, FIG. 3.
The support 12 is adapted to slidably mount a drill guideway 24. The guideway 24 includes an elongated platelike member 26 fastened thereto which is slidably retained in opposed grooves 28 extending longitudinally in the support 12. The guideway 24 also includes a pair of longitudinal grooves 30 adapted to slidably support a fluid operated rock drill motor 32 which includes laterally projecting gibs 34 disposed in the grooves 30. The drill motor 32 is adapted to transmit percussive energy and rotary motion to an elongated drill rod 36 having a bit portion 38 disposed on the rod end. The drill rod 36 is guided by suitable supporting devices 40 and 42 commonly known as centralizers. The centralizer 40 is mounted on the guideway 24 and the centralizer 42 is suitably mounted on the support 12. The centralizers 40 and 42 are desirably of the well known hinged jaw type which permit lateral insertion of drill rods into the centralizer support jaws.
As shown in FIG. 1 the end of the guideway 24 opposite the end to which the centralizer 40 is attached is provided with a bracket 44 upon which pressure fluid operated rotary motors 46 and 48 are mounted adjacent each other. The rotary motor 46 is of the reversible type and includes a shaft 50 which is connected by a coupling 52 to an elongated member comprising a power screw 54. The power screw 54 is disposed between the grooves 30 and is rotatably supported by a bearing support 56 which also supports the centralizer 40 on the guideway 24. The power screw 54 is engaged with a nut 58 disposed on the drill motor 32. In response to rotation of the motor 46 the power screw 54 is operable to feed the drill motor reversibly along the guideway 24 in a manner well known.
The motor 48 is reversible and also includes a shaft 60 which is connected by a coupling 62 to a second elongated member comprising a power screw 64 disposed adjacent and parallel to the power screw 54. The power screw 64 is also rotatably supported on the guideway 24 by a suitable bearing support 66 mounted on the member 26. The power screw 64 is threadedly engaged with a cooperating nut 68 nonrotatably mounted on the end of the support 12 opposite the end at which the centralizer 42 is mounted. In response to rotation of the motor 48 the power screw 64 is operable to feed the guideway 24 reversibly along the support 12 to extend or reduce the overall effective feed length of the feed mechanism 10. With the arrangement of the support 12 and guideway 24 of the present invention the centralizer 40 may be used to provide intermediate support for relatively long drill rods which may be used when the feed mechanism is operated to feed the drill motor from the fully extended position of the guideway 24 with respect to the support 12. Moreover, the location of the power screw 64 under the guideway 24 provides for some protection from falling rock and dust.
The feed mechanism 10 is advantageously used in combination with mobile drill rigs such as the rig 70 illustrated in FIGS. 4 and 5. The drill rig 70 includes a wheeled undercarriage 72 upon which is pivotally mounted the boom 22 adapted to be supported and moved by pressure fluid cylinder actuators 74 and 76. The rig 70 is illustrated as being disposed in an underground tunnel 78. In the position of the rig shown in FIG. 5 the feed mechanism 10 is positioned for drilling the longitudinal end face 80 of the tunnel and adequate space is available to allow the guideway 24 to be extended with respect to the support 12. The drill motor 32 is initially positioned at the rearward end of the guideway 24 to provide for using a relatively long drill rod 82. Accordingly, the effective feed length of the feed mechanism 10 is increased and relatively long holes may be drilled, without the addition of drill rod sections, in a single pass of the drill motor 32 along the guideway 24 and of the guideway 24 along the support 12. In a preferred mode of operation the motors 46 and 48 are simultaneously supplied with pressure fluid from a single source to provide for feeding the drill motor along the guideway 24 and for telescoping the guideway 24 to the position shown in FIG. 1. As previously mentioned, the motors 46 and 48 are reversible and may be simultaneously operated to retract the drill motor 32 along the guideway 24 and extend the guideway 24 to the position shown in FIG. 5.
The feed mechanism 10 may also be advantageously used to provide for drilling holes where space limitations require a shorter feed length than is provided by the feed mechanism in the condition shown in FIG. 5. Referring to FIG. 4 the feed mechanism 10 is shown positioned for drilling holes in the sidewall 84 of the tunnel 78. The tunnel 78 is of insufficient width to accommodate the feed mechanism in the extended condition. Accordingly, prior to positioning the feed mechanism 10 for drilling the sidewall 84 the drill rod 82 is replaced by a shorter drill rod 36 and the motor 48 is operated to telescope the guideway 24 into a retracted position with respect to the guideway 12. The motor 48 is then rendered inoperable or locked by suitable operating controls, as will be explained further herein, and the motor 46 is operated to feed the drill motor reversibly along the guideway 24.
Referring to FIG. 6, the feed mechanism 10 of the present invention is advantageously operated in combination with a control circuit partly shown in schematic form. The control circuit illustrated in FIG. 6 is intended to be used in conjunction with a major portion of the control system for rock drills disclosed in U.S. Pat. No. 3,561,542 to L.B. Hanson et al. Reference to specific portions of the control system of the above mentioned patent will be made in the description of the control circuit and operation thereof shown in FIG. 6 and said patent will hereinafter be referred to as the '542 patent.
The control system for the telescopic feed mechanism 10 includes a reversible pressure fluid motor 86 connected to a reversible fluid pump 87 preferably operating on hydraulic fluid. The pump 87 is connected to the motors 46 and 48 in a closed circuit arrangement whereby the motors may operate independently if one or the other is stalled, or operate simultaneously whereby a feeding force on the drill may be provided by either motor or both motors simultaneously. The total feed force would be the same regardless of the condition of operation. A two-position manually operated control valve 89 is interposed in a conduit 90 leading to the motor 48. The valve 89 is operable to be positioned to provide for fluid flow to the motor 48 or to prevent fluid flow to the motor from the pump 87. In this way the motor 48 may be controlled to be inoperative when it is desired to operate the feed mechanism in the position shown in FIG. 4 under conditions in which the guideway 24 is not to be moved with respect to the guideway 12. The motor 86 may receive pressure fluid from a suitable source for reversible operation and desirably can be provided with pressure fluid at a regulated pressure from the control system of the '542 patent by connecting conduits 91 and 92 leading to the motor with the conduits designated 120 and 130 shown in FIG. 1 of the '542 patent. The motors 46 and 48 would then be operable at a regulated fluid pressure derived from the pump 87 which in turn would be controlled by the motor 86. The motor 86 would be operative to receive pressure fluid from the control system of the '542 patent in place of the rock drill feed motor disclosed therein.
The feed mechanism 10 also may be provided with a position sensing circuit as shown in FIG. 6 whereby a pressure fluid signal may be generated when the drill motor 32 has been fed forwardly as far as the feed mechanism can provide. The sensing circuit of FIG. 6 also provides for a pressure fluid signal to be generated when the drill motor has been retracted along the guideway 24 to the starting position and the guideway 24 has been extended with respect to the guideway 12. If the feed mechanism 10 is being operated with the guideway 24 telescoped and inoperative the sensing circuit can be controlled by the valve 89 to provide a signal when the drill has been returned to the starting position on the guideway 24.
The guideway 24 is provided with sensing means comprising the three-way, two-position valves 93 and 94 disposed on the guideway 24. The valves 93 and 94 are spring biased to be in position a and are mechanically actuated by suitable projections 95 and 96 on the drill motor 32 to be respectively actuated to position b. The support 12 is provided with sensing means in the form of similar two-position valves 97 and 98 which are positioned on the support 12 so that they may be actuated to their positions b by respective projections 99 and 100 on the guideway 24. Pressure fluid such as compressed air is supplied to the sensing valves 97 and 98 from a suitable source by way of conduits 101 and 103. Sensing valve 97 is connected in series to sensing valve 94 by conduit 104 and sensing valve 98 is connected in series to sensing valve 93 by conduit 105. Accordingly, when the motors 46 and 48 have advanced the drill motor 32 so that projection 95 actuates valve 93 to position b and the guideway 24 has been telescoped along the support 12 so that projection 100 actuates valve 98 to position b a pressure fluid signal is produced in conduit 108. This signal may be used to indicate that the drill motor has been fed forwardly in drilling to a forward limit position of the useful feed length of the feed mechanism 10. Moreover, the signal generated in conduit 108 may be transmitted to the conduit designated with numeral 134 in the drawings of the '542 patent to effect automatic reversal of the motor 86 and accordingly the motors 46 and 48 in accordance with the description of operation of the rock drill control systems disclosed in the '542 patent.
The sensing valves 97 and 94, when both actuated to their positions b by extension of the guideway 24 and return of the drill motor 32 to the position shown in FIGS. 1 and 5, will provide a pressure signal in conduit 109 which can be used to indicate that the feed mechanism 10 is in the rearward limit position with respect to the drilling face. Furthermore, the conduit 109 can be connected to conduit designated with numeral 102 in the '542 patent so that a pressure signal generated in conduit 109 can be used to shut off the operation of the motor 86 and drill motor 32. It is assumed that the drill motor, drill support and position sensing circuit portion shown in FIG. 1 of the '542 patent would be replaced by the feed mechanism 10 and control circuit of FIG. 6 of the instant disclosure.
The position sensing control of the present invention may be operated to reverse the feed direction and shut off the drill motor or indicate the need to do so when the feed mechanism 10 is operated in the telescoped condition as shown in FIG. 4. For operation in the telescoped condition the valve 98 will be held in position b by the projection 100 due to the telescoped position of the guideway 24 with respect to the support 12. Accordingly, when valve 93 is actuated by the drill motor 32 to position b a signal will be generated in conduit 108. The manually actuated valve 89 is shifted to position b to render the motor 48 inoperable and to provide a supply of pressure air to conduit 104. A check valve 110 prevents backflow and escape of air through valve 97 which is in position a. With a supply of pressure air in conduit 104 a pressure air signal will be generated in conduit 109 when the projection 96 on the drill motor actuates valve 94 to position b thereby providing a signal that the drill motor has returned to the starting position on the guideway 24. Accordingly, the telescoping feed mechanism 10 in combination with the position sensing control circuit provides an improved drilling system which may be adapted for automatic control of the drilling cycle if the feed mechanism is operated either in the extended or telescoped mode.
Referring to FIG. 7 an alternate embodiment of a position sensing control circuit for the feed mechanism 10 is shown in schematic form. The control circuit of FIG. 7 includes signal relay means comprising a plurality of two position valves 120a, 120b, 120c, and 120d which are spring biased in position a and are fluid actuated to position b. Valves 120a and 120c are connected to the same pressure fluid source as conduits 101 and 103. Valves 120b and 120d are respectively series connected to valves 120a and 120c. A conduit 122 connected to valve 120d may be connected to conduit 102 of the control system of the '542 patent and a conduit 124 may be suitably connected to the conduit 134 of the '542 patent and to the valve 120b of FIG. 7. As shown in FIG. 7 the fluid actuators of valves 120a- d are respectively in communication with valves 94, 97, 98, and 93 and are each actuated to their position b when a pressure signal is received from the respective associated valve. Conduit 103 is connected to continuously supply pressure fluid to valves 93 and 94 as well as valve 98. The pressure fluid actuator of valve 120b is connected via a conduit 125 to receive pressure fluid from valve 89 when the latter valve is manually shifted to position b for operation of the feed mechanism 10 in the telescoped position of the guideway 24 with respect to support 12. A check valve 126 prevents leakage of pressure fluid through valve 97 from conduit 125.
Accordingly, when valves 93 and 98 have been actuated to position b, valves 120c and 120d will be actuated to position b and a pressure signal will be generated in conduit 122 indicating that a forward limit position of the drill motor and guideway has been reached. In like manner when valves 94 and 97 have been actuated to position b valves 120a and 120b will be actuated to position b to provide a pressure fluid signal in conduit 124 indicating that the drill motor 32 and guideway 24 have both reached a rearward limit position.
Elongated supports or guideways on which a rock drill motor is reversibly moved therealong by a power screw are well known and advantageously used in underground drilling because of their relative light weight and ease of mounting on movable booms. In many tunneling operations it is desirable to provide a drill feed mechanism which will permit drilling relatively long holes in one pass of the drill along the feed support which support may also be telescoped or reduced in length to provide for drilling where space limitations in the tunnel will allow only comparatively short feed mechanisms to be positioned. Various arrangements of telescopic fluid cylinder and piston feed devices have been used to meet the requirements of the abovementioned operating conditions without providing the advantages of light weight and reliability enjoyed by power screw type feed mechanisms.
SUMMARY OF THE INVENTION
The present invention provides a telescopic feed mechanism for rock drills which may be extended to provide a relatively long feed length where working conditions permit and which may be telescoped to reduce the length of the feed mechanism for operation in restricted work spaces.
The present invention also provides a telescopic feed mechanism for rock drills which is of the lightweight power screw type which may be mounted on the distal end of a movable boom structure for maneuvering into positions where space limitations require the use of the feed mechanism in the telescoped condition.
The present invention further provides a telescopic feed mechanism in which dual power screws are driven independently by fluid motors which may be selectively operated to feed a drill motor along a guideway or to feed both a drill motor along a guideway while feeding the guideway along a support member. Moreover, the present invention contemplates a control circuit including position sensors operative to provide a signal when the drill motor and guideway have been fed forward or retracted to the limits of the feed mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal elevation partially sectioned of a telescopic feed mechanism in accordance with the present invention;
FIG. 2 is a transverse section taken along lines 2--2 of FIG. 1;
FIG. 3 is a partial longitudinal elevation of the feed mechanism of FIG. 1;
FIG. 4 is a transverse elevation of a mobile rock drill unit upon which the telescopic feed mechanism of FIG. 1 is mounted for operation in the telescoped condition;
FIG. 5 is a longitudinal elevation of the mobile rock drill unit shown in FIG. 4 with the telescopic feed shown in the extended position;
FIG. 6 is a schematic diagram of a control circuit for the telescopic feed mechanism of the present invention; and,
FIG. 7 is a schematic diagram of an alternate embodiment of a control circuit for the telescopic feed mechanism of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 through 3 the feed mechanism of the present invention is generally designated by the numeral 10 and includes an elongated support 12 adapted to be slidably retained by guides 13 which are mounted on a feed support 14. The feed support 14 is of a type which includes a pressure fluid cylinder and piston assembly 16 having the distal end of a piston rod 18 connected to the support 12 for moving the feed mechanism 10 with respect to the support 14 as shown by the positions of the feed mechanism in FIGS. 4 and 5. The feed support 14 is pivotally mounted on a positioner device 20 which in turn is mounted on the distal end of a movable boom 22, FIG. 3.
The support 12 is adapted to slidably mount a drill guideway 24. The guideway 24 includes an elongated platelike member 26 fastened thereto which is slidably retained in opposed grooves 28 extending longitudinally in the support 12. The guideway 24 also includes a pair of longitudinal grooves 30 adapted to slidably support a fluid operated rock drill motor 32 which includes laterally projecting gibs 34 disposed in the grooves 30. The drill motor 32 is adapted to transmit percussive energy and rotary motion to an elongated drill rod 36 having a bit portion 38 disposed on the rod end. The drill rod 36 is guided by suitable supporting devices 40 and 42 commonly known as centralizers. The centralizer 40 is mounted on the guideway 24 and the centralizer 42 is suitably mounted on the support 12. The centralizers 40 and 42 are desirably of the well known hinged jaw type which permit lateral insertion of drill rods into the centralizer support jaws.
As shown in FIG. 1 the end of the guideway 24 opposite the end to which the centralizer 40 is attached is provided with a bracket 44 upon which pressure fluid operated rotary motors 46 and 48 are mounted adjacent each other. The rotary motor 46 is of the reversible type and includes a shaft 50 which is connected by a coupling 52 to an elongated member comprising a power screw 54. The power screw 54 is disposed between the grooves 30 and is rotatably supported by a bearing support 56 which also supports the centralizer 40 on the guideway 24. The power screw 54 is engaged with a nut 58 disposed on the drill motor 32. In response to rotation of the motor 46 the power screw 54 is operable to feed the drill motor reversibly along the guideway 24 in a manner well known.
The motor 48 is reversible and also includes a shaft 60 which is connected by a coupling 62 to a second elongated member comprising a power screw 64 disposed adjacent and parallel to the power screw 54. The power screw 64 is also rotatably supported on the guideway 24 by a suitable bearing support 66 mounted on the member 26. The power screw 64 is threadedly engaged with a cooperating nut 68 nonrotatably mounted on the end of the support 12 opposite the end at which the centralizer 42 is mounted. In response to rotation of the motor 48 the power screw 64 is operable to feed the guideway 24 reversibly along the support 12 to extend or reduce the overall effective feed length of the feed mechanism 10. With the arrangement of the support 12 and guideway 24 of the present invention the centralizer 40 may be used to provide intermediate support for relatively long drill rods which may be used when the feed mechanism is operated to feed the drill motor from the fully extended position of the guideway 24 with respect to the support 12. Moreover, the location of the power screw 64 under the guideway 24 provides for some protection from falling rock and dust.
The feed mechanism 10 is advantageously used in combination with mobile drill rigs such as the rig 70 illustrated in FIGS. 4 and 5. The drill rig 70 includes a wheeled undercarriage 72 upon which is pivotally mounted the boom 22 adapted to be supported and moved by pressure fluid cylinder actuators 74 and 76. The rig 70 is illustrated as being disposed in an underground tunnel 78. In the position of the rig shown in FIG. 5 the feed mechanism 10 is positioned for drilling the longitudinal end face 80 of the tunnel and adequate space is available to allow the guideway 24 to be extended with respect to the support 12. The drill motor 32 is initially positioned at the rearward end of the guideway 24 to provide for using a relatively long drill rod 82. Accordingly, the effective feed length of the feed mechanism 10 is increased and relatively long holes may be drilled, without the addition of drill rod sections, in a single pass of the drill motor 32 along the guideway 24 and of the guideway 24 along the support 12. In a preferred mode of operation the motors 46 and 48 are simultaneously supplied with pressure fluid from a single source to provide for feeding the drill motor along the guideway 24 and for telescoping the guideway 24 to the position shown in FIG. 1. As previously mentioned, the motors 46 and 48 are reversible and may be simultaneously operated to retract the drill motor 32 along the guideway 24 and extend the guideway 24 to the position shown in FIG. 5.
The feed mechanism 10 may also be advantageously used to provide for drilling holes where space limitations require a shorter feed length than is provided by the feed mechanism in the condition shown in FIG. 5. Referring to FIG. 4 the feed mechanism 10 is shown positioned for drilling holes in the sidewall 84 of the tunnel 78. The tunnel 78 is of insufficient width to accommodate the feed mechanism in the extended condition. Accordingly, prior to positioning the feed mechanism 10 for drilling the sidewall 84 the drill rod 82 is replaced by a shorter drill rod 36 and the motor 48 is operated to telescope the guideway 24 into a retracted position with respect to the guideway 12. The motor 48 is then rendered inoperable or locked by suitable operating controls, as will be explained further herein, and the motor 46 is operated to feed the drill motor reversibly along the guideway 24.
Referring to FIG. 6, the feed mechanism 10 of the present invention is advantageously operated in combination with a control circuit partly shown in schematic form. The control circuit illustrated in FIG. 6 is intended to be used in conjunction with a major portion of the control system for rock drills disclosed in U.S. Pat. No. 3,561,542 to L.B. Hanson et al. Reference to specific portions of the control system of the above mentioned patent will be made in the description of the control circuit and operation thereof shown in FIG. 6 and said patent will hereinafter be referred to as the '542 patent.
The control system for the telescopic feed mechanism 10 includes a reversible pressure fluid motor 86 connected to a reversible fluid pump 87 preferably operating on hydraulic fluid. The pump 87 is connected to the motors 46 and 48 in a closed circuit arrangement whereby the motors may operate independently if one or the other is stalled, or operate simultaneously whereby a feeding force on the drill may be provided by either motor or both motors simultaneously. The total feed force would be the same regardless of the condition of operation. A two-position manually operated control valve 89 is interposed in a conduit 90 leading to the motor 48. The valve 89 is operable to be positioned to provide for fluid flow to the motor 48 or to prevent fluid flow to the motor from the pump 87. In this way the motor 48 may be controlled to be inoperative when it is desired to operate the feed mechanism in the position shown in FIG. 4 under conditions in which the guideway 24 is not to be moved with respect to the guideway 12. The motor 86 may receive pressure fluid from a suitable source for reversible operation and desirably can be provided with pressure fluid at a regulated pressure from the control system of the '542 patent by connecting conduits 91 and 92 leading to the motor with the conduits designated 120 and 130 shown in FIG. 1 of the '542 patent. The motors 46 and 48 would then be operable at a regulated fluid pressure derived from the pump 87 which in turn would be controlled by the motor 86. The motor 86 would be operative to receive pressure fluid from the control system of the '542 patent in place of the rock drill feed motor disclosed therein.
The feed mechanism 10 also may be provided with a position sensing circuit as shown in FIG. 6 whereby a pressure fluid signal may be generated when the drill motor 32 has been fed forwardly as far as the feed mechanism can provide. The sensing circuit of FIG. 6 also provides for a pressure fluid signal to be generated when the drill motor has been retracted along the guideway 24 to the starting position and the guideway 24 has been extended with respect to the guideway 12. If the feed mechanism 10 is being operated with the guideway 24 telescoped and inoperative the sensing circuit can be controlled by the valve 89 to provide a signal when the drill has been returned to the starting position on the guideway 24.
The guideway 24 is provided with sensing means comprising the three-way, two-position valves 93 and 94 disposed on the guideway 24. The valves 93 and 94 are spring biased to be in position a and are mechanically actuated by suitable projections 95 and 96 on the drill motor 32 to be respectively actuated to position b. The support 12 is provided with sensing means in the form of similar two-position valves 97 and 98 which are positioned on the support 12 so that they may be actuated to their positions b by respective projections 99 and 100 on the guideway 24. Pressure fluid such as compressed air is supplied to the sensing valves 97 and 98 from a suitable source by way of conduits 101 and 103. Sensing valve 97 is connected in series to sensing valve 94 by conduit 104 and sensing valve 98 is connected in series to sensing valve 93 by conduit 105. Accordingly, when the motors 46 and 48 have advanced the drill motor 32 so that projection 95 actuates valve 93 to position b and the guideway 24 has been telescoped along the support 12 so that projection 100 actuates valve 98 to position b a pressure fluid signal is produced in conduit 108. This signal may be used to indicate that the drill motor has been fed forwardly in drilling to a forward limit position of the useful feed length of the feed mechanism 10. Moreover, the signal generated in conduit 108 may be transmitted to the conduit designated with numeral 134 in the drawings of the '542 patent to effect automatic reversal of the motor 86 and accordingly the motors 46 and 48 in accordance with the description of operation of the rock drill control systems disclosed in the '542 patent.
The sensing valves 97 and 94, when both actuated to their positions b by extension of the guideway 24 and return of the drill motor 32 to the position shown in FIGS. 1 and 5, will provide a pressure signal in conduit 109 which can be used to indicate that the feed mechanism 10 is in the rearward limit position with respect to the drilling face. Furthermore, the conduit 109 can be connected to conduit designated with numeral 102 in the '542 patent so that a pressure signal generated in conduit 109 can be used to shut off the operation of the motor 86 and drill motor 32. It is assumed that the drill motor, drill support and position sensing circuit portion shown in FIG. 1 of the '542 patent would be replaced by the feed mechanism 10 and control circuit of FIG. 6 of the instant disclosure.
The position sensing control of the present invention may be operated to reverse the feed direction and shut off the drill motor or indicate the need to do so when the feed mechanism 10 is operated in the telescoped condition as shown in FIG. 4. For operation in the telescoped condition the valve 98 will be held in position b by the projection 100 due to the telescoped position of the guideway 24 with respect to the support 12. Accordingly, when valve 93 is actuated by the drill motor 32 to position b a signal will be generated in conduit 108. The manually actuated valve 89 is shifted to position b to render the motor 48 inoperable and to provide a supply of pressure air to conduit 104. A check valve 110 prevents backflow and escape of air through valve 97 which is in position a. With a supply of pressure air in conduit 104 a pressure air signal will be generated in conduit 109 when the projection 96 on the drill motor actuates valve 94 to position b thereby providing a signal that the drill motor has returned to the starting position on the guideway 24. Accordingly, the telescoping feed mechanism 10 in combination with the position sensing control circuit provides an improved drilling system which may be adapted for automatic control of the drilling cycle if the feed mechanism is operated either in the extended or telescoped mode.
Referring to FIG. 7 an alternate embodiment of a position sensing control circuit for the feed mechanism 10 is shown in schematic form. The control circuit of FIG. 7 includes signal relay means comprising a plurality of two position valves 120a, 120b, 120c, and 120d which are spring biased in position a and are fluid actuated to position b. Valves 120a and 120c are connected to the same pressure fluid source as conduits 101 and 103. Valves 120b and 120d are respectively series connected to valves 120a and 120c. A conduit 122 connected to valve 120d may be connected to conduit 102 of the control system of the '542 patent and a conduit 124 may be suitably connected to the conduit 134 of the '542 patent and to the valve 120b of FIG. 7. As shown in FIG. 7 the fluid actuators of valves 120a- d are respectively in communication with valves 94, 97, 98, and 93 and are each actuated to their position b when a pressure signal is received from the respective associated valve. Conduit 103 is connected to continuously supply pressure fluid to valves 93 and 94 as well as valve 98. The pressure fluid actuator of valve 120b is connected via a conduit 125 to receive pressure fluid from valve 89 when the latter valve is manually shifted to position b for operation of the feed mechanism 10 in the telescoped position of the guideway 24 with respect to support 12. A check valve 126 prevents leakage of pressure fluid through valve 97 from conduit 125.
Accordingly, when valves 93 and 98 have been actuated to position b, valves 120c and 120d will be actuated to position b and a pressure signal will be generated in conduit 122 indicating that a forward limit position of the drill motor and guideway has been reached. In like manner when valves 94 and 97 have been actuated to position b valves 120a and 120b will be actuated to position b to provide a pressure fluid signal in conduit 124 indicating that the drill motor 32 and guideway 24 have both reached a rearward limit position.