CA1265601A - Programmed automatic drill control - Google Patents

Programmed automatic drill control

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Publication number
CA1265601A
CA1265601A CA000526404A CA526404A CA1265601A CA 1265601 A CA1265601 A CA 1265601A CA 000526404 A CA000526404 A CA 000526404A CA 526404 A CA526404 A CA 526404A CA 1265601 A CA1265601 A CA 1265601A
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CA
Canada
Prior art keywords
value
command value
penetration rate
drilling parameter
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000526404A
Other languages
French (fr)
Inventor
Richard A. Jasinski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Caterpillar Global Mining LLC
Original Assignee
Becor Western Inc
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Filing date
Publication date
Application filed by Becor Western Inc filed Critical Becor Western Inc
Application granted granted Critical
Publication of CA1265601A publication Critical patent/CA1265601A/en
Expired legal-status Critical Current

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  • Automatic Control Of Machine Tools (AREA)

Abstract

Abstract of the Disclosure A programmed automatic drill control for optimizing the drilling of subterranean holes by large drilling machinery such as blast hole drills. Sensing means are provided to sense a first set of drilling parameter limits to effect maximum r.p.m. of the motor to rotate the pipe drilling bit and to sense a second set of drilling parameter limits to effect a maximum rate for the motor to drive the hoist pull-down mechanism. These conditions will prevail until a sensed limit is reached or the drilling conditions require operation along a torque or force limit set value. When a limit is reached, the control will regulate at a value of r.p.m. or rate which is consistent with maintaining opera-tion at the limit value. In a preferred embodiment, the sensing of a first set of drilling parameters include a sensing of head position of the pipe drilling bit, the force on the drilling bit as well as vertical and horizontal vibration of a drilling pipe and the sensing of a second set of drilling parameters include sensing head position of the pipe drilling bit, the horizontal and vertical vibration of the drilling pipe, the rotary amps and speed of the motor to drive the drill pipe and the air pressure in the drill pipe.

Description

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This invention relates generally to a system and methcd Gf operating electric motor driven drilling machinery, and more par-ticularly to a systern and method for computer controlled drilling in a blast hole drill wherein drilling conditions of the blas-t hole drill are continuously sensed and the penetration rate and drilling rotational speed are optimized independently.
Various prior art systems have been developed utilizing compu-ters to automatically control large drilling apparatus.
For example, in U. S. Pa-tent No. ~,354,233 a computer is utilized in conjunction with a blast hole drill for comput-ing the value of drilling hole penetration for a single revolution. The computer is connected to means for compar ing the current value of a drilling tool penetration per single revolution with preset values. The computer is connected with its inputs to transducers and setters of input parameters, such as rotation frequency, axial load, torque, and the vibration speed of a rotary drill. In the U~ S. Patent No. ~,165,789 a control algorithm and a micro-computer is employed with a memory to maintain a maximum rate of penetration for drilling roof bolt holes. Optimi-zation is based on regulating drill revolutions per minute and thrust while holding one of those parameters constant andvarying the other. Control systems for blast hole drills are also described in U. S. Patent Nos~ 3,581,830; 3,593,807 and 3,613,805. In the '630 patent the control system bal-ances rotary torque and downfeed force to reduce downfeed speed when torque feedback exceeds a predetermined value.
Signals derived from both torque and drilling rate are util-ized in the '807 patent to provide optimum efficiency of r-~

operation. Automatic depth control is provided in the contro] system described in the '~05 patent as ~ell as automatic shut down.
Although automatic drill control systems have been constructed and used, they have not been employed to optimize the automatic drilling of a blast hole in the most efficient manner. One of the prior art systems is directed toward optimizing drilliny rates by holdiny certain drilling parameters constant while varyi~y others in search of optimization. Another c4mpares torque with a signal which may in part be based on human experience and ePfects a further siynal to control throuyh the motor drive a downward pressure on the drill so that a maximum drilling rate can be obtained through strata of various and different composition.
The present invention aims to provide an improved control system and method for drilling subterranean holes.
The shortcomings of the prior art are overcome by the continuously and efficiently operating drilling machinery having a first electric motor to rotate a drill pipe with attached drilling bit and a second electric motor to operate a hoist pulldown mechanism for applying axial forces on the drill pipe, the drill control system comprising: means to set a revolutions per minute (RPM) command value, the RPM command value representing a desired commanded rotational speed for said drill pipe;
first sensing means for sensing a first set of drilling parameter values, including drilling parameter values representing only the horizontal component of the vibration being produced by the drill pipe and the axial ~orce being exerted on the frill pipe by the second electric motor; RPM correction means connected to receive the RPM command value and the first set of drilling parameter values, the RPM correction means including a plurality of predetermined limit values, each predetermined limit value being associated with one drilling parameter value in the first set of drilling J~
~ 3 parameter values, the RPM correction means producing a corrected RP~ command value in which the RPM correction means reg~llates the corrected RPM command val~le at the level of the RPM command value while all drilling parameter values in the first set of drilling parameter values are below the associated predetermined limits, and in which the RPM correction mean~ regulates the corrected RPM command values at a level l.ess than the RPM command value while any one of the dril.ling parameter values in the first set o~ drilling parameter values is equal to the associated predetermined limit so as to maintain all drilling parameter values in the first set of drilliny parameter values at or below the associated predetermined limits; ~irst drive means connec-ted to receive the corrected RPM command value for driving the first electric motor to achieve the rotational speed of the drill pipe corresponding to the corrected RPM command value; means to set an axial penetration rate command value, the axial penetration rate command value representing a desired commanded axial velocity for the drill pipe in terms of axial length of drill pipe advancement per unit of time' second sensing means for sensing a second set of drilling parameter values, including a drilling parameter values representing only the vertical componen-t of the vibration being produced by the drill pipe and the pressure of clearing air being injected into the drill pipe; axial penetration rate correction means connected to recei~e the axial penetration rate command value and the second set of drilling parameter values, the axial penetration rate correction means including a plurality of predetermined limit values, each predetermined limit value being associated with one drilling parameter value in the second set of drilling parameter values, the axial penetration rate correction means producing a corrected axial penetration rate command value in which the axial penetration rate correction means regulates the corrected axial penetration rate command value at the level o~ the axial penetration rate command value while all drilling r~

- 3a -parameter values in the secon~ set of clrilliny parameter values are below the associated predetermined limits, and in which the axi.al penetration rate correction means regulates the corrected axial penetration rate command value a-t a level less than the axial penetration rate command value while any one of the drilling parameter values i.n the second set oE dri.lling parameter v~lues is equal to the associated predetermined lim;.t so as ko maintain all drilling parameter values in the second set of drilliny parameter values at: or below the associated predetermlned limit; second drlve means connected to receive the corrected axial penetrati.on rate command value for driviny the second electric motor to achieve the axial velocity of the drill pipe corresponding to the corrected axial penetration rate command value.
One advantage of the system o~ this invention is that the system effects optimization in an automatic manner.
Another advantage of the system of the invention is that it can provide a maximum penetration rate within restxaints of the blast hole drill (BHD).
With the system of the present invention there is reduced maintenance and down time through efficient and proper operation of the BHD.
Another advantage of the system of this invention is that it can be readily adapted to currently used BHDs.
In one pre~erred embodiment, the means to sense the first set of drilling parameter limits includes means to sense head position of the pipe drilling bit, the force on the drilling bit, as well as vertical and horizontal vibration of a drilling pipe.
In yet another embodiment, the means to sense the second set of drilling parameter limits includes means to sense head position of the pipe drilling bit, the horizontal and vertical vibration of the drilling pipe, the force on the drill pipe and the rotary amp3 and speed of the motor to rotate t}~e drill pipe and the air pressure in the drill pipe.
In another embodiment, means are operatively connected to said sensing means for the rotary amps and ~peed of the drill pipe motor to sense ~tallin~ of the bit and to effect a hoist control operation.
In still another embodiment, means are afforded in conjunction with the means ko sense the air pressure to sense a clog~ed drilling hole and to effect a hoist control operation.
The drill control system of this invention differs from the prior drill control systems in commanding the maximum desired r.p.m. for the electric drilling motor and the rate for the hoist pulldown mechanism. These values are main-tained until sensed limits are reached or the drilling conditions require operation along the force and torque limit set v~lues. When the limits are reached, the control system will regulate at a value of r.p.m. or rate which is consistent with maintaining operation at the limit values.
Unlike the prior art systems, the parameters monitored for the limits are rotary current overload, excessive vertical and/or horizontal vibration and excessive main air pressure.
During operation in the force or torque limit region, the actual r.p.m. or rate of penetration will be dictated by the material being dril~e~. In the instance of commanding the ma~imum drilling r.p.m., i the drill bit operational specifi-cations or a horizontal or vertical vibrations limit is reached during operation in the torq~le limit region and in the instan~e of commanding the maximum drilling rate, if a rotary current, horizontal or vertical vibration or air ~4~ BE-803 - :.,, pressur~ limit i~ reached durin~ operation in the force limit re~ion, the control system will regulate based on the actual value of developed r.p.m. or rate not the desired maximum r.p.m. or rate.

Brief Description of ~
Fig. 1 is a plan view of a blast hole drill shown in conjunction with the control system of the present i~vention, which is illustrated in a diagrammatic block representation.
Fig. 2 is a function block diagram of the control por-tion for the rotary drive of the system of Fig. l.
Fig. 3 is a functional block diagram of part of the control portion for the hoist pulldown drive of the system of Fig. 1.
Fiy. 4 is a functional block diagram similar to Fig. 3 showing the remaining part of the control for the hoist pulldown drive of the system.
Fig. S is a diagrammatic illustration o~ the control system of this invention connected to a computer.

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Figs. 6A and 6B are flow charts showing a gerleral signal flow block diagram for the drill control sys~em of this invention.

Descripticn of the Preferred Embodiment Referring to Fig. 1, a blast hole drill generally ~0 includes the usual crawler vehicle 11 by which it can be mo~ed from location to location. It is supported in ~

working position and raised and lowered to this position by four double acting hydraulic jacks with one of the rear jacks shown at 12 and one of the front jacks shown at 13.
The jacks are mounted on a main frame 14 which is supported ~2~5~

on the crawler and serves as a platEorm for the drill mast 17. The drill mast is raised and lowered by the hydraulic cylinder 18 and the -telescoping strut 19 as well as suitably positioned for angle drilling. Also supported on the main frame 1~ is the operations cab 16 and the housing 15 ~or operating machinery. Positioned in the mast 17 are the usual rotary motor 20 for rotating -the drill pipe 23 and the bit 96. Also posi~ioned in the mast 17 ls a hoist pulldown mechanism 21 including a hoist pulldown motor 22. ThePADCis generally designatedin Figure 1 andis shown operatively con-nected to a rotary drive25 for the rotary motor 20aswellas a hoist pulldown drive 26 for the,hoistpulldown motor 22. The PADC 2~1atits output side controls the r.p.m.command 27 for the rotary drive 25 and the rate command 28 for the hoist pull-down drive 26. As indicated, the fadc 24 is connected at its input side 29 and 30 to certain drilling parameter limits generally 31 and certain sensors generally 32 for control-ling rotary drive r.p.m. command 27 and for controlling the rate command 28 of the hoist pulldown drive 26.
In the drawing an * designation is indicated in conjunc-tion with certain descriptions. These are commonly used in the industry to indicate a command signal.
Referring now to Fig. 2, the means to sense the first set of sensed drilling parameter limits and the sensors for controlling the rotary drive r.p.m. command 27 is described in detail. It will include a head depth determination 33 determined in the algorithm function box 34 into which is placed the inputs of hole depth 35, maximum desired r.p.m.
36, collar depth 37 and minimum desired r.p.m. 38. With the r.pOm. commancl 39 set as a function of depth, the remaining algoriths in the generation of the final reference command 70 will act to reduce the r.p.m. if a monitored parameter limit is exceeded. These r.p.m. correction routine~, once active, will correct the r.p.m. to a ]evel which will main-tain the monitored parameter at its limit. This will be effected basically through the summer 40 as will another limit determination which i~ an r.p.m. correction 41 for the drilling bit operational specifications. It is based on maintaining a specified relationship between the speecl (r.p.m.) of the bit and the force applied to the bit. This is effected by inputting the maximum r.p.m. 42, the low r.p.m. 43, a high ~orce 44 and a low forca limits 45 into algorithm function box 46 which applies the indicated formula wherein M represents the slope of the r.p.m. force function and B represents a r.p.m. X-Y graph intercept with a force equal to zero as represented by the equation Y= B+Mx with M
indicating the slope. The M results 47 and the B results 48 of these formulae are further applied in algorithm function box 49 where the indicated formula is applied in conjunction with the actual force 189 on the bit 96 when switch 188 is closed by the bit on ground detector 121. This results in a calculat~d r.p.m. 50 which represents the maximum r.p.m.
allowable at the present magnitude of force. This calculated r.p.m. 50 is fed into function box 51 which has an r.p.m.
low input 124, a low force input 52 and a high force input 53. This information will be factored according to the indicated parameter graph to result in an r.p.m. correction factor as a function of force for ~it specifications 54 which is also added to the summer 40~
The means to sense the first set of sensed drilling parameter limits and the sensors also include a horizontal vibration input 55 indicated as a r.p.m. correction as a -7~ BE-803 .. . ..

function of horizontal vibration 66 and a vertical vlbration input 103. Vibration input signal 103 i ~ubjected ~o a scaling function in the scalar box 57, the resulting r.p.m.
correction a~ a function of vertical vibration 58 being fed to the summer 40. The horizontal vibration input 55, as i5 the vertical vibration input 56, is first effected by detec-tion means composed of an accelerometer (not shown~ and a transducer (not shown). In this instance the vertical vibration sensing mean~ iB placed on the base of the mast 17 and the horizontal vibration sensing means is positioned on the drilling main frame 14 next to the mast 17. The horizon-tal input 55 is directed into a function box 59 where a sample hold and scaling function will take place. The resultant signal 60 representing a magnitude of horizontal vibration is fed to a summer 61 and compared to a horizontal vibration limit bias 6~, the output 63 of which is directed into a regulator and scaling function 64. The resulting r.p.m. correction factor for horizontal vibration 65 is fed to the summer 40. This horizontal vibration correction factor 65 is also subjected to a minimum level detector function i~ function box 67 resulting in a horizontal vibra-tion correction 68. This vibration correction is used to reduce the drilling rate by means of an automatic drill rate control as represented at 68 in Fig. 3 as will be later
2~ explained. ~eferring again to the summer 40, tha r.pOm.
correction factor as a function of the bit specification 54 and as a function of the r.p.m. ~8 and 65 of the vertical and horizontal vibration r.p.m. correction factor reduce the r.p.m. command 39 in the summer 40 to a resultant r.p.m.
command 70 to a value which will hold these factors at a set limit. The resultant r.p.m. command 70 can be urther , . ~ . .

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corrected for tor~le rotation 71 and the speed of rotation 72 ~n a scaling and torgue limit correction box 73. It should be pointed out that in this instance the torque limit correction will take into accounk what conditions are taking S place in term~ of what the BHD 10 is experiencing with respect to torque, spee~ and conditioRs encountered. The~e correction factors will reduce the resulting value of r.p.rn.
command 27 to effect operation of the BHD 10 along a torque limit set value by governing the rotary drive 25 of the rotary motor 20.
The means to sense the second set of sensed drilliny parameter limits and the sensors which determine the rate 28 of drilling are now described, first with reference to Fig.
3. The first involves the setting of the rate command 28 as a function of depth. This is accomplished by entering encoder data 74 indicating the depth of the drill bit 96 in a depth positi~n calculation box 75 which will contain the zero reset 76 and a tool wrench 77 input. The zero reset 76 is used to define a zero point or start of the hole. The tool wrench input 77 is employed to detect when the drill bit 96 is not moving because the drill pipe 23 is clamped.
In this instance the encoder will be of the usual typ~P and located in the hoist machinery drill bo~ such as indicated at 21. As stated previously in conjunction with Fig. 2 and the function box 34, the head depth 33 will be calculated in conjunction with calculations for a hole depth 35, a maximum rate 36, a collar depth 37 and a collar rate 38 in the function box 34 to result in a desired rate command 78 as a function of depth for input into the summer 79. With the rate command set as a function of depth, the remaining algorithms in the generation of the final reference command ~9~ BE-803 ~ is~
122 will act to reduce the rate if a monitored parameter limit i5 ~xceeded. These rate correction routines, once active, will correct the rate to a level which will maintain the monitored parameter at its limit. This will be effecked basically through the summer 79 as will be further explained.
Another determination which composes one of the sensors 32 is a det0rmination of the rate command 28 as a function o~
the rotary load 80 of the motor 20 to rotate the drill pipe 23. This is based on calculating the root-mean-s~uare (RM5) armature current in the function box 81 by the indicated formula wherein Ia2 = the square of the armature current and SCAN mean~ the time reguired or the computer 140 to go through the program one time. The RMS current is calculated over a fixed time period as indicated by a scan timer 82 and a 180 second clock 83.
In this function box 81 the RMS current is compared to the rated motor current of the rotary drill motor ~0. If the RMS current 84 is greater than the rated motor current, a cooldown period of time is calculated such as in the cooldown calculator B5. The cooldown period is the time in which the rotary motor must operate at a reduced load such that the RMS current ~or the combined fixed and cooldown period is equal to the rated motor current. This is accom plished through the time signal 86 in conjuction with the coold~wn timer 87 to operate the switch 91. The rotary load 80 is also added to ~he summer 89 with the current at a rated bias 8B, the result of which is added and further regulated by the amp regulator and scaling function 9D.
When the switch 91 is closed through the in~luence of the cooldown timer 87, the resulting rate correction as a unc-tion of Rotary Load (RC*RL) 92 will be added to the summer -lO~ BE-803 r~

79. The RC~RL i~ ther~by activ~ during the cooldown period.
It reduces the rate command 122 to a value which cause~
rotary load to be at its reduced cooldown period load.
If at any time during the run-pulldown mode, a con~
dition of excessive rotary loading of motor 20 at near zero rotary speed is present, a stalled bit routine is acti~ated.
This is effected through the function box 93 which will contain a calculated rotary ~peed (Ncal) input 94. A command signal 117 can be given to a hoist control 132 and change the mode state to a run hoist if a stalled bit routine i~
detected as well as to terminate the injection of water or dust control. In the run-hoist mode, the PADC will by means of the hoist control 132 and locating knowledge of the bit location 33 off the bottom of the hole attempt to correct the stalled bit condition. If the condition is cleared, the mode is returned to a run-pulldown and the drilling process will continue. If the condition is not cleared the ~ode is changed to idle and appropriate fault indicating lamps are set as will be discussed later in conjunction with the ccmputer 140 shown in Fig. 5.
A determination of the rate command 28 correction is also a funrtion of the vertical and horizontal ~ibration and is based on monitoring the root mean-square values of the vertical and horizontal acceleration rates of the drill m~st 2~ 17 and deck 14. This is accomplished by the additional rate command correction basad on force of vertical vibration 95 having ~he vertical vibration sensor input 56 (sPe Fig. 4).
Input S6 is subjected to a sample hold aDd scaling function 99 ~efore bei~g Eed to the summer 97 which also receives signals from a vertical vibration limit bias 98. The signal results 96 of the summer 97 are regulated and scaled such as ~ BE-803 ..~.

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at the functlon box 100. The resulting rate~ correction factor as a function of vertical vibration :104 is added to the summer 79. In addition, the rate coxrection by ho~izon-tal vibration value 107 for the previously described hori-S zontal vibration input 6~ is introduced to the summer 79after a scaling function 106 (See Fig. 3). The rate correc-tion factor as a function of vertical vibration 104 and the rate and/or horizontal vibration inputs correction factor a~
a function of horizontal vibration :107 reduce the rate command 78 in the summer 79 to a resultant rate command 122 to a value which will hold vibration at a set limit. It should be pointed out that the correction rate for vertical vibration has a greater effect at reducing vibration than correction of the rate for horizontal vibration. It should also be noted that there is a vibration level detéctor 102 utilized in conjunction with the rate correction by vertical vibration value 104 for the purpose of detecting a level rate reduction command so as to reduce the r.p.m. in an automatic drill rotary control. This is shown at 103 as a vertical vibration correction signal and is introduced into the summer 40 as previously described in Fig. 2.
The rate comma~d 28 also includes an air pressure detection function 101 for sensing the pressure 69a rom air compressor pressure 69 which is monitored at 113 and added in the summer 110. If the pressure exceeds a limit as set in regulator a~d scaling box 111, the rate correction by air pressure 112 reduces the rate command 78 at the summer 79 and output 122 to a val~e which will hold the main air pressure at its set limit. If the magnitude of the rate correction 112 reaches a leYel of correction which will cause the rate to equal zero, a clogged bit condi~ion is . . .

12~
activated. Th~ water lnjection control 118 is effected through the rate level detector 114 to issue the clogged bit command 116 to the water injection control 118 which acti-vates an on/off status 120 to command suitable valving to stop water flow. The stalled bit s:ignal 117 from stall bit detector 93 can also cause water injection control 118 to turn off. The level detector 114 in this instance detects any rate reduction command. An on/off status 185 governs the water injection control 118. In a run-hoiet operation the PADC will attempt to correct the clogged bit condition.
If the condition is cleared, the mode state is returned to a run-pulldown and the drilling process will continue. If the condition is not clearecl, the mode is changecl to idle and appropriate fault indicating lamps are set as will be explained later in conjunction with Fig. 5. An additional level detector 115 detects a maximum rate correiction command and is also connected to the air pressure rate signal 112.
It is utilized in conjunction with hoist control 132 for the purpose of activating the hoist control and hoisting the bit 96 off the bottom wh~n a clogged hole is detected. (See Fig. 3).
It will be ~een that the summer 79 in conjunction with rate command 78, the vibration factors 107 and 104, the air pressure rate 112 and the rotary load factor 92 effect a rate 28 of pulldown along 2 drilling parameter limit set value 31 which is consis~ent with maintaining operation at the limit value. ~he resultant rate command 122 from the summer 79 will also be acted upon by a scaling box 123 to convert the rate c:ommand signal 122 to a signal r~te command 125 to be further acted upon by the force limit region rate correction functic)n 126. This r~te correction function will ~$S~
consider the actual force 127 and the actual rate 12~, both at a steady state mode for operating BHD 10. This resulting rate 129 can be interrupted by the swi~ch 130 acted upon by the hoist control 132 which will consider such factors as the hoist speed limit 131, a hole depth limit 134, the stalled bit condition 117 and a clogged hole condition 136.
The hoist control 132 will also operate a switch 133 in conjunction with the OR function 137 which indicates a logic operation wherein the rate command 129 or the hoist control output l90 can be fed to the scaling box 138 for the purpose o setting the rate command 28 to the proper units required by the hoist pulldown drive 26 to ultimately result in the rate of pulldown 28. It should also be noted that in con junction with hoist control 132 that a bit position and hole depth function is provided by the depth signal 33 through depth position calculator 75. This is also presented to the bit on ground detector 121 to activate switch 188 (See Fig.
2) for the purpose of calculating a bit force only when the bit 96 is on the ground.
~0 A computer 140 is shown in Fig. 5 to control variousfunc-tions fox the PA~C ~4, many of which have been previously described. It is available from the Allen-Bradley Company, Inc. and available as model No. PLC2-05. A position encoder 74 feeds head position information to the computer 140 by way of a serial receiver card 141 and a transistor-transistor logic input and output 183 and 184, respectively. Output 184 is connected to the transistor-transistor input module 142 which feeds head information to the standard programmable logic control apparatus 143. An analog input module 144 receives nine analog signal inputs. One is from an air measuring pressure transducer 113 sensing main air pressure : `'' ' .

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from compressor 69; another from the horizontal vibration monitor 55 and the third from the vertical vibration monitor 56. As indicated above, the horizontal and vertical vibra-tion monitors 55 and 56 receive ~ignals from the accelero-meters 96 and 105. Six additional analog inputs are alsoreceived in module 144, three each oi which are from the rotary and hoist pulldown motion control drives. They are indicated by the input line 147 and :L48, respectively and represent motor parameters o~ æpeed, armature current and terminal volts. An analog output module 149 provides three analog outputs. These are the speed control reference command signals 27 and 28 to the rotary and hoist pulldown drives 25 and 26 as well as a selectable voltaye output signal 150 which can be selected to monitor one hundred locations internal to the programmable logic controller.
Rotary and hoist pulldown drives 25 and 26 can be further controlled by operator controlled master rotary switches 113. The relay contacts A.M.R.l and A.M.R.2 determine if the PADC si~nals 27 and 28 or the master switches 113 provide the r.p.m. and rate command to the rotary and hoist pulldown drives 25 and 26. A current limit switch 135 is also con-v/ nected to the hoist pulldown drive 26.
A thumbwheel switch matrix 151 consists of 34 binary coded decimal thumb-wheel dial switches used to input drill-ing parameter limits 29 into the PADC software algorithms.Twenty-four light emitting diodes as shown at 152 will represent eight lines each from computer module outputs 153, 154 and 186. An LED four-digit display meter 155 is also interconnected with the computer 140 to selPctively display lOQ locations internal to it. A 120-volt A~ input module 156 consists of switches, push buttons and logic signals ~5~
which indicate the state of the blast hole drill to the computer such as an automatic drill on/off or automatic drill automatic/manual mode. An output interface 157 con-sists of reed relays and indicating lamps which indicate the state of the PADC to other blast ho:Le drill components such as a bit on bottom, stalled bit or clogged hole condition and as well as A.M.R.l, and A.M.R.2. The usual DC power block line 158 provides the necessa:ry voltage and current requirements or the computer 140.
Turning to Fig. 6, a general flow block diagram is presented to indicate the vario-ts seguences of actions in operating the PADC by means of the software acted upon by the computer 140. '~he signal flow blocks are indicated by the reference numerals 159-lRZ.
The first calculation is one of bit position lS9 which will include collar depth 37, wet hole and end of hole depth 35. Also considered is zero bit 96 movement 76 and the bit on the bottom. A mode selection 160 is next ef~ected based on input information and previous scan results. It includes selection of an off mode, an idle mode, a run-hoist mode and a run pulldown mode. I~ block 161, there is effected a data file generation wherein based on the mode selected and the block transfer status, the thumbwheel 151 data is transferred to the tempor~ry area and then to the data storage area.
2S Next is a bi* perfor~ance calculation 162. If the mode is idle or run, there is calcuated bit rate of penetration 73 and 126, bit force lB9, bit torque 71, 127 and bit r.p.m.
72, 128. The rate for HPD motor 22 is set as a function of depth such as ind.icated in block 163 and in funct.ion box 34 associated with sensor 32. The rate correction as a func-tion of rotary load 187 is next effected at block 164. At , , ,, . ~, . .. .. ... . .
:..

block 165 a stalled bit condition is determined as at func-tion box ~3 which the PADC will attempt to correct. A rate correction is then made at 166 as a fur.ction of main air pressure such as at 101. At block 167 a clogged bit deter-mination is made such as at 136. If bit is clogged, theauto drill will attempt to correct the problem. Rate cor-rection as a function of vertica7 and horizontal vibration 56 and 55 is then made at 168. A correction of the rate as a function of depth 78 is made at 169 by rotary load 92, air pressure 112 and vibration 104 and 107. A corrected rate is made at 170 if the operation is at a force limit. Block 171 represents a determination if the PADC should activate the hoist control. A decision is made accordingly. At blocX
172 the r.p.m. for the motor 20 is made as a function o depth as indicated in function box 34 associated with sensor 31. An r.p.m. determination is made at 173 for operation within the prescribed ~it specifications such as performed in function box 51. At block 174 there is a correction of the r.p.m. for the bit specification 54 and horizontal and vertical vibration 65 and S8. Next at 175 there is a cor-rection of the r.p.m. for operation at torque limit as provided in function box 73. A re-check is next made at 176 of the mode selection based on current scan conditions.
Based OD the re-check made at 176, the r.p.m. command 27 and the rate command 28 is set at block 177. At block 178 the status of the water injection control (function box 118) based on auto-dri:Ll status is made. Next at 179 is the loading of output registers for display 155 and test jack outputs 150. The transistor-transistor logic status lamp conditions 152 are set based on auto-drill status at 180.
In block 181, the 120 VAC output 157 is set based on auto ;

~ s~
drill status and in block 182 there ls an enabling or in-hibiting of the appropriate block transfer of the input and output data based on the mode.
The programmed automatic drill control 24 of this invention has been described in conjunction with a blast hole drill. It should be apparent to one skilled in the art that the programmed automatic drill control of this inven-tion could be adapted to other drilling-type equipment, for example an oil drilling apparatus. Similarly, the progra~med automatic drill control could be advantageously used with any type of earth drilling equipment where fast and maximum efficiency of the drilling apparatus is to be accomplished.
In the foregoing description a computer 140 has been described having various functions for indicating operation and controlling the automatic programmed drill control.
Many of these, while advantageous, are not necessary such as the switches, push buttons and logic signals. Alternatively, other controls, signalling or switching devices csuld be used as is readily apparent to those skilled in the art.

~18- BE-803 :

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A drill control system for continuously and efficiently operating drilling machinery having a first electric motor to rotate a drill pipe with attached drilling bit and a second electric motor to operate a hoist pulldown mechanism for applying axial forces on the drill pipe, the drill control system comprising: means to set a revolutions per minute (RPM) command value, the RPM
command value representing a desired commanded rotational speed for said drill pipe; first sensing means for sensing a first set of drilling parameter values, including drilling parameter values representing only the horizontal component of the vibration being produced by the drill pipe and the axial force being exerted on the frill pipe by the second electric motor; RPM correction means connected to receive the RPM command value and the first set of drilling parameter values, the RPM correction means including a plurality of predetermined limit values, each predetermined limit value being associated with one drilling parameter value in the first set of drilling parameter values, the RPM correction means producing a corrected RPM command value in which the RPM correction means regulates the corrected RPM command value at the level of the RPM command value while all drilling parameter values in the first set of drilling parameter values are below the associated predetermined limits, and in which the RPM correction means regulates the corrected RPM command values at a level less than the RPM command value while any one of the drilling parameter values in the first set of drilling parameter values is equal to the associated predetermined limit so as to maintain all drilling parameter values in the first set of drilling parameter values at or below the associated predetermined limits; first drive means connected to receive the corrected RPM command value for driving the first electric motor to achieve the rotational speed of the drill pipe corresponding to the corrected RPM command value; means to set an axial penetration rate command value, the axial penetration rate command value representing a desired commanded axial velocity for the drill pipe in terms of axial length of drill pipe advancement per unit of time;
second sensing means for sensing a second set of drilling parameter values, including a drilling parameter values representing only the vertical component of the vibration being produced by the drill pipe and the pressure of clearing air being injected into the drill pipe; axial penetration rate correction means connected to receive the axial penetration rate command value and the second set of drilling parameter values, the axial penetration rate correction means including a plurality of predetermined limit values, each predetermined limit value being associated with one drilling parameter value in the second set of drilling parameter values, the axial penetration rate correction means producing a corrected axial penetration rate command value in which the axial penetration rate correction means regulates the corrected axial penetration rate command value at the level of the axial penetration rate command value while all drilling parameter values in the second set of drilling parameter values are below the associated predetermined limits, and in which the axial penetration rate correction means regulates the corrected axial penetration rate command value at a level less than the axial penetration rate command value while any one of the drilling parameter values in the second set of drilling parameter values is equal to the associated predetermined limit so as to maintain all drilling parameter values in the second set of drilling parameter values at or below the associated predetermined limit; second drive means connected to receive the corrected axial penetration rate command value for driving the second electric motor to achieve the axial velocity of the drill pipe corresponding to the corrected axial penetration rate command value.
2. The drill control system of claim 1 which includes: means for setting a collar depth value; means for setting a normal RPM value; means for setting a collaring RPM value; means for setting a normal axial penetration rate value; means for setting a collar axial penetration rate value; and means for sensing the current depth of the hole and producing a current hole depth value; and in which the means to set an RPM command value includes means for setting the RPM command value as a function of the current hole depth value, wherein if the current hole depth value is less than the collar depth value then the RPM command value is set to the collaring RPM value, and if the current hole depth value is greater than or equal to the collar depth value then the RPM
command value is set to the normal RPM value; and in which the means to set an axial penetration rate command value includes means for setting the axial penetration rate command value as a function of the current hole depth value, wherein if the current hole depth value is less than the collar depth value then the axial penetration rate command value is set to the collar axial penetration rate value, and if the current hole depth value is greater than or equal to the collar depth value then the axial penetration rate command value is set to the normal RPM
value.
3. The drill control system of claim 1 in which the second sensing means includes means for sensing the current being drawn by the first electric motor, and the second set of drilling parameter values includes a value representing the current being drawn by the first electric motor, and in which the axial penetration rate correction means includes a cooldown control means, the cooldown control means comprising: average current calculation means connected to the current sensing means for accumulating a time average effective current value of the current being drawn by the first electric motor; current regulator means also connected to current sensing means, the current regulator means producing an output proportional to the amount by which the sensed current exceeds the current rating of the first electric motor, and switching means connected to receive the time average effective current value, the switching means being operative to test the time average effective current value against the current rating of the first electric motor, and if the current rating is exceeded, then the switching means applies the output of the current regulator means to the axial penetration rate correction means for reducing the corrected axial penetration rate command value for as long as the current rating is exceeded.
4. The drill control system of claim 1 which includes: rotary current sensing means for sensing the current being drawn by the first electric motor in producing rotary motion of the drill pipe; rotary speed sensing means for sensing the rotary speed of the drill pipe; stalled bit detection means connected to the rotary current sensing means and the rotary speed sensing means, the stalled bit detection means producing a stalled bit induction to the hoist control means when the rotary speed of the drill pipe falls below a predetermined minimum rotary speed value and the rotary current exceeds a predetermined maximum rotary current value; and control means connected to the stalled bit detection means and to the means for setting the RPM command value and the axial penetration rate command value, wherein upon reception of a stalled bit indication from the stalled bit detection means, the control means forces the RPM command value and the axial penetration rate command value to zero, and provides a fault indication of the stalled bit condition.
5. The drill control system of claim 1 which includes: hoist control means for controlling the operation of the second electric motor, the hoist control means including switching means interposed between the axial penetration rate correction means and the second drive means in order to selectively interrupt the connection of the corrected axial penetration rate command value to the second drive means and instead produce a hoist command value and connect the hoist command value to the second drive means, the hoist command value causing the second drive means to reverse the direction of the second electric motor thereby reversing direction of the axial velocity of the drill pipe; and in which the axial penetration rate correction means includes means for decreasing the corrected axial penetration rate command value when the drilling parameter value representing the pressure of air being injected into the drill pipe is near the associated predetermined limit value, and in which the axial penetration rate correction means includes means for providing a clogged bit indication to the hoist control means if the pressure of air being injected into the drill pipe is greater than or equal to the associated predetermined limit value; wherein upon reception of the clogged bit indication from the clogged bit detection means, the hoist control means engages the switching means to automatically raise the drill pipe to relieve the clogged bit condition without manual intervention.
6. A method for continuously and efficiently operating drilling machinery having a first electric motor to rotate a drill pipe with attached drilling bit and a second electric motor to operate a hoist pulldown mechanism for applying axial forces on the drill pipe, the method comprising: setting a revolutions per minute (RPM) command value, the RPM command value representing a desired commanded rotational speed for said drill pipe;
sensing a first set of drilling parameter values, including drilling parameter values representing only the horizontal component of the vibration being produced by the drill pipe and the axial force being exerted on the drill pipe by the second electric motor; producing a corrected RPM command value based on the RPM command value, the first set of drilling parameter values, and a plurality of predetermined limit values, each predetermined limit value being associated with one drilling parameter value in the first set of drilling parameter values, such that the corrected RPM command value is regulated at the level of the RPM command value while all drilling parameter values in the first set of drilling parameter values are below the associated predetermined limits, and such that the corrected RPM
command value is regulated at a level less than the RPM
command value while any one of the drilling parameter values in the first set of drilling parameter values is equal to the associated predetermined limit so as to maintain all drilling parameter values in the first set of drilling parameter values at or below the associated predetermined limit; driving the first electric motor to achieve the rotational speed of the drill pipe corresponding to the corrected RPM command value; setting an axial penetration rate command value, the axial penetration rate command value representing a desired commanded axial velocity for the drill pipe in terms of axial length of drill pipe advancement per unit of time;
sensing a second set of drilling parameter values, including drilling values representing only the vertical component of the vibration being produced by the drill pipe and the pressure of a clearing medium being injected into the drill pipe; producing corrected axial penetration rate command value based on the axial penetration rate command value, the second set of drilling parameter values, and a plurality of predetermined limit values, each predetermined limit value being associated with one drilling parameter value in the second set of drilling parameter values, such that the corrected axial penetration rate command value is regulated at the level of the axial penetration rate command value while all drilling parameter values in the second set of drilling parameter values are below the associated predetermined limits, and such that corrected axial penetration rate command value is regulated at a level less than the axial penetration rate command value while any one of the drilling parameter values in the second set of drilling parameter values is equal to the associated predetermined limit so as to maintain all drilling parameter values in the second set of drilling parameter values at or below the associated predetermined limit; driving the second electric motor to achieve the axial velocity of the drill pipe corresponding to the corrected axial penetration rate command value.
7. The method of claim 6 which includes the steps of: setting a normal RPM value; setting a collar depth value; setting a collaring RPM value; and sensing the current depth of the hole and producing a current hole depth value; and in which the step of setting an RPM
command value sets the RPM command value as a function of the current hole depth value, wherein if the current hole depth value is less than the collar depth value then the RPM command value is set to the collaring RPM value, and if the current hole depth value is greater than or equal to the collar depth value then the RPM command value is set to the normal RPM value; and in which the step of setting an axial penetration rate command value sets the axial penetration rate command value as a function of the current hole depth value, wherein if the current hole depth value is less than the collar depth value then the axial penetration rate command value is set to the collar axial penetration rate value, and if the current hole depth value is greater than or equal to the collar depth value then the axial penetration rate command value is set to the normal axial penetration rate value.
8. The method of claim 6 in which the step of sensing a second set of drilling parameter values includes sensing the current being drawn by the first electric motor, and the second set of drilling parameter values includes a value representing the current being drawn by the first electric motor, and in which the step of producing a corrected axial penetration rate command value includes the steps of: accumulating a time average effective current value of the sensed current being drawn by the first electric motor; producing a current regulator output proportional to the amount by which the sensed current exceeds the current rating of the first electric motor; and testing the time average effective current value against the current rating of the first electric motor, and if the current rating is exceeded, then reducing the corrected axial penetration rate command value for as long as the current rating is exceeded.
9. The method of claim 6 which includes the steps of: sensing the current being drawn by the first electric motor in producing rotary motion of the drill pipe; sensing the rotary speed of the drill pipe;
producing a stalled bit indication when the rotary speed of the drill pipe falls below a predetermined minimum rotary speed value and the rotary current exceeds a predetermined maximum rotary current value; and upon activation of the stalled bit indication, forcing the RPM
command value and the axial penetration rate command value to zero, and providing a fault indication for the stalled bit condition.
10. The method of claim 6 which includes the steps of: decreasing the corrected axial penetration rate command value when the drilling parameter value representing the pressure of air being injected into the drill pipe is near the associated predetermined limit value, and providing a clogged bit indication to the hoist control means if the pressure of air being injected into the drill pipe is greater than or equal to the associated predetermined limit value; wherein upon activation of the clogged bit indication from the clogged bit detection means, raising the drill pipe to relieve the clogged bit condition without manual intervention.
CA000526404A 1986-04-08 1986-12-29 Programmed automatic drill control Expired CA1265601A (en)

Applications Claiming Priority (2)

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US84953886A 1986-04-08 1986-04-08
US849,538 1986-04-08

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CA1265601A true CA1265601A (en) 1990-02-06

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AU (1) AU594993B2 (en)
CA (1) CA1265601A (en)
ZA (1) ZA869508B (en)

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DE10304405B4 (en) * 2003-02-01 2012-10-04 Hilti Aktiengesellschaft Method for controlling a core drilling machine

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US3613805A (en) * 1969-09-03 1971-10-19 Bucyrus Erie Co Automatic control for rotary drill

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ZA869508B (en) 1987-08-26
AU594993B2 (en) 1990-03-22
JPS62236990A (en) 1987-10-17

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