A METHOD AND AN EQUIPMENT FOR ADJUSTING ROCK DRILLING

Abstract: A method for optimizing rock drilling, wherein the drilling is adjusted by means of one or more adjustable parameters such as the feed rate and the rotation rate. In the method, a set value (Hs) of each adjustable parameter is deviated in accordance with a sinusoidal curve while integrating a change caused by the deviation in the penetration rate (x) and adding it to the set value (Hs) so that the set value (Hs) shifts closer to an optimum penetration rate (xopt).

Description: A method and an equipment for adjusting rock drilling The invention relates to a method for optimiz¬ ing rock drilling, wherein a penetration rate of a drill bit of a drilling machine into a rock is measured and the operating parameters of a drilling equipment are adjusted to maximize the penetration rate. The invention also relates to an equipment for realizing the method described above, comprising control devices for giving set values to a percussion apparatus of a rock drilling equipment, a rotation rate of a drill bit and a feed force, and means for measuring a penetration rate of the drill bit. As is well known, the adjustment of a rock drilling machine is based on set values and limits determined by the operator, who sets the percussion power, the rotation power and the feed on the basis of his experience so as to optimize the drilling result. This procedure is poor and it often results in equipment damages or inferior drilling results. European Patent Specification 112 810 discloses a method in which the percussion rate and percussion frequency of a percussion hammer is measured and varied until the maximum penetration rate is achieved. The frequency and percussion rate are varied so that the percussion power remains substan¬ tially constant all the time. A disadvantage of the method is that one attempts to maximize the penetra- tion rate by means of the percussion frequency and the percussion rate, which, in practice, are inter¬ dependent control parameters. In practice, the method can thus be regarded as an adjustment based on a single parameter. Moreover, in this method, a change does not affect the momentary value of the penetration rate, if the measurement of the penetra¬ tion rate is disturbed in some way, and so the method is unreliable to a certain extent and cannot optimize the drill penetration with sufficient accuracy. The object of the present invention is to provide a method for adjusting a drilling process, which optimizes the penetration rate as efficiently and reliably as possible irrespective of any distur¬ bances affecting the measuring result. The method according to the invention is characterized in that the operating parameters are adjusted one at a time while the other operating parameters are kept sub¬ stantially constant, that a continuous deviation is caused to occur symmetrically on both sides of the set value of the operating parameter to be ad usted, that a change caused by the deviation in the penetra¬ tion rate is measured, that when the change caused by the deviation in the penetration rate is different on different sides of the set value, the set value is adjusted on the basis of the measurements in a direction in which the penetration rate increases, and that when a maximum value of the penetration rate is substantially achieved by adjusting one operating parameter, the operating parameter to be adjusted is changed. The equipment according to the invention is characterized in that the control devices comprise automatically operated adjusting means which deviate one operating parameter at a time from its set value, measure variation in the penetration rate, and shift the deviated set value in a direction in which the penetration rate increases, said adjusting means changing the operating parameter to be deviated when the set value being adjusted reaches a value substan¬ tially corresponding to a maximum penetration rate. The basic idea of the invention is that the operating parameters are monitored one at a time by subjecting each parameter to a continuous, regular deviation occurring reciprocally and symmetrically, so that it can be seen on which side of the set value the penetration rate increases, and so the value of the parameter can be shifted towards a greater penetration rate on the basis of the deviation of the parameter. After one parameter is settled to its max¬ imum value, a deviation is caused in the next para- meter, and this is continued from one parameter to another in a predetermined circulating order so that the penetration rate of the- drill bit is maximized, and the maximum value of the penetration rate can be achieved automatically as the conditions change with- out any procedures carried out by the operator. The invention is described in more detail by means of the attached drawings, in which Figure 1 is a graphic representation of the adjusting method according to the invention when realized with respect to one adjustable parameter; Figures 2a to 2c illustrate the adjusting method according to the invention graphically; Figure 3 is a graphic representation of the method according to the invention when realized with respect to two adjustable parameters; Figure 4 is a graphic representation of an adjusting equipment for realizing the method accord¬ ing to the invention; and Figure 5 illustrates schematically the connec- tion of the adjusting equipment according to the in¬ vention to a rock drilling equipment for performing the drilling. Figure 1 is a graphic representation of the adjusting method according to the invention realized with respect to one adjustable parameter Hf. A penetration rate x ig repreS ented by a curve F which forms a convex pattern in the coordinate system x - H f . When the other operating parameters are constant, the penetration rate reaches its optimum at a point A, which is the highest point of the curve F. In normal conditions, it is to be expected that the po¬ sition of the point A is not actually known, because the drilling conditions vary, and so the shape of the curve F, for instance, may change momentarily so that the position of the point A on the axis Kf changes. It is, however, possible to aim at achieving the optimal point Hf 0 _.*-. momentarily on the curve F by applying the method of the invention. Essential is that there is a set value H s for the operating para- meters of the feed rate, for instance, on the basis of which value the adjustment equipment adjusts the drilling so that the feed rate corresponds to the set value H s _ As the optimum value H fop1: corresponding to the highest penetration rate on the axis Hf is not actually known, the value of the set value H s has to be estimated so that it may be set to a point B on the curve F, for instance. In this case, the set value and the optimum value __£„,.■_ differ from each other, and the drilling is not as efficient as possible. According to the basic idea of the inven¬ tion, the set value H s is now deviated by a small sinusoidal oscillation from its nominal value to the same extent on its both sides, while measuring the magnitude of variation in the penetration rate. In the case of the point B, the penetration rate thereby increases with the set value H s and correspondingly decreases with the set value H s . As a result of this measurement, the set value H s is shifted by means of the adjusting equipment in a direction in which the penetration rate increases, until the value H f 0p t corresponding to the current drilling conditions is achieved. Similarly, if the set value H s results in the situation represented by a point C, a decrease in the set value H s indicates an increase in the penetration rate, and an increase in the set value indicates a decrease in the penetration rate. The adjusting equipment shifts the set value H s so that its value decreases until the penetration rate Hf OD .*- optimal in the current conditions is achieved. Figures 2a to 2c show control curves corre¬ sponding to the points A to C in Figure 1. Figure 2a* j _ shows a situation in which the penetration rate is at its optimum, and the deviation value is 0 at this value of the penetration rate. Figure 2a2 shows that the penetration rate x is constant, and Figure 2a shows the shape of a deviation function V with respect to the set value H s . As the integrated product of the deviation function V and the penetra- tion rate x is constant, it indicates that the penetration rate is at its optimum, that is, as high as possible in the current conditions. Figure 2b shows a control curve corresponding to the point B. Figure 2b-*_, in turn, illustrates the product x * V of the penetration rate and the deviation function. It can be seen from Figure 2b*-_ that the change caused by the deviation function V in the penetration rate is positive as integrated, i.e. its area is positive, and so the area of curve portions on the positive side is greater than the area of curve portions on the negative side. As a result, it can be seen that the penetration rate changes as a function of the deviation in the same direction as the deviation in Figure 2b2, while the deviation curve V in Figure 2b has the same shape as the deviation curve in Figure 2a 3 . As a result, the set value H g of the adjustable parameter is integrated similarly as described in connection with Figure 1, that is, in a positive direction, until the set value H g is at the optimum point H£ or)t . Figure 2c* j _, in turn, shows a curve cor¬ responding to the point C, in which the integration obtained on the basis of the product of the penetra¬ tion rate x and the deviation function V, i.e., the area of the curve portions on the negative side of the curve is greater than the area of the curve portions on the positive side. Correspondingly, as shown in Figure 2c2, the penetration rate x varies inversely and, as shown in Figure 2cg, the deviation curve varies similarly as in Figure a3_ As a result, the integration of the set value H g takes place in a negative direction, that is, the set value H s de¬ creases until it reaches the point A, that is, the penetration rate Hf--.*.. Figure 3 illustrates, similarly as Figures 1 and 2, the method according to the invention when applied with respect to two operating parameters H^ and H r . In this case, when certain conditions prevail, e.g. the percussion power is constant, the interdependent set values of the feed and the rotation rate form a convex surface with a pre¬ determined maximum point, that is, x max with respect to the penetration rate. Assume that the feed and the rotation are originally set to initial values H£ Q and H ΓQ , which give an operating point P Q . The point P Q corresponds to a point X Q on the convex surface, which is the starting point. In this situation, the feed, for instance, is adjusted first by feed adjust¬ ing means, and a set value corresponding to the max¬ imum penetration rate is determined for the feed at a predetermined fixed rotation rate by subjecting the set value of the feed force to a sinusoidal deviation and by adjusting the feed force as described above in connection with Figures 1 and 2. When the feed force is adjusted, its set value is shifted from the point Hf Q to a point H f t , so that the drill penetration rate is correspondingly shifted from the point P Q to a point P-_ , which corresponds to the maximum point of the penetration rate when the rotation rate is set to H ΓQ . This point corresponds to the point _•_-■_ on the convex surface representing the penetration rate. Thereafter the feed force is maintained at its set value H f0 _. , and the rotation rate is adjusted according to the invention so that it decreases to a value H r t while the penetration rate increases from the point X j to a point x max , thus obtaining the max¬ imum value of the penetration rate in this drilling situation in constant conditions. This procedure is continued by again adjusting the feed force and then again the rotation rate, so that the operation can be constantly kept at the point x max , and the adjustment only ensures that this is the case. An abrupt change in conditions affects the shape of the convex sur¬ face, and the position of the maximum point x max of the penetration rate in the coordinate system changes accordingly. To restart the optimization of the drilling process, the adjustment is continued as de¬ scribed above. If it is assumed that the change takes place when the feed force is adjusted, the obtained set value for the feed will be fixed, and the rotation rate is adjusted by the method according to the invention by employing a sinusoidal deviation of the set value of the rotation rate, thus obtaining the maximum point x max of the penetration rate at said set value of the feed force with respect to the rotation rate. Thereafter the rotation rate is again adjusted to a fixed value, and the feed force is again subjected to a sinusoidal deviation, and the maximum feed value is determined at this rotation rate. The set values are thus varied one after the other in such a way that the other is fixed and the other is deviated in accordance with a sinusoidal curve, and the deviation is integrated so that the maximum point x max in the current conditions is achieved finally after a sufficient number of alternate deviations. A change in the drilling con¬ ditions, of course, affects the shape of the convex surface and thus the "point x op - | - or x max is shifted. As the alternate deviation of the adjustable para¬ meters is continued throughout the drilling process, the adjustment automatically adapts itself to changes in the conditions and adjusts the drilling process continuously so that the drilling takes place as close as possible to the maximum penetration rate, i.e., the point x max on the surface, in the prevail- ing conditions. Figure 4 shows an adjusting equipment for realizing the method according to the invention. The adjusting equipment comprises a percussion adjuster 1 forming a closed adjusting circuit and arranged to control a percussion machinery 2. The operation of the percussion machinery is measured and the results are applied to a comparator 3. A set value R_ for the percussion is also applied to the comparator 3 from adjusting means, and the comparator 3 compares the set value of the percussion with the measured percus¬ sion value and controls the percussion adjuster 1 so that the actual value of the percussion is equal to the set value. The adjusting equipment further com¬ prises a feed adjustment optimizer 4 which is con- nected to a comparator 5. The comparator 5 applies an adjustment value E f to a feed adjuster 6 which, in turn, is connected to control a feed apparatus 7. The feed apparatus 7 applies a measured value Yf to the comparator 5, which compares the set value of the feed adjuster and the measured value Yf and controls the feed adjuster 6 on the basis of the difference so that the feed rate is kept at a desired value. The adjusting equipment also comprises a rotation adjust¬ ment optimizer 8 having an output, i.e. a set value R r connected to a comparator 9. A difference value E r of the comparator 9, in turn, controls a rotation rate adjuster 10, which controls a rotation motor 11. A rotation rate value Y r is measured from the rotation motor 11 and applied back to the comparator 9, which determines the difference E r between the set value R r and the actual value Y r . A penetration rate x, the value of which is arranged to control both the feed adjustment optimizer 4 and the rotation adjustment optimizer 8, is measured from the feed apparatus. The adjusting means further comprise a controller i.e. a control logic 12, which connects deviation adjusters of the feed adjustment optimizer and the rotation adjustment optimizer alternately in operation so that a small sinusoidal deviation is caused to occur alternately in the set value Rf and R r of one adjuster, while the other remains constant. Consequently, it is possible in the feed apparatus to measure variation in the feed rate, i.e. penetration rate, by means of a measuring device, and so the adjusting means of the optimizer circuits 4 and 8 can integrate the set value on the basis of the variation in the penetration rate towards a set value cor¬ responding to a higher penetration rate. This enables a rock breaking process 13 performed by the percus- sion machinery 2, the feed apparatus 7 and the rotation apparatus 11 to be optimized in accordance with the invention both when the conditions change and when they remain unchanged during the drilling process. Figure 5 shows schematically the connection of the adjusting equipment according to the invention to a conventional drilling equipment for performing a drilling process. Figure 5 shows a drilling machine 13 to which a drill rod 14 is attached. A drill bit 15 is attached to the end of the drill rod. The drilling machine 13 is mounted on a feed beam 16 longitudinally movably with respect to it. Drill rod centralizers 17 and 18 are also mounted on the feed beam so as to support the drill rod during the drilling; they are well known and therefore will not be described in greater detail herein. The drilling equipment further comprises a motor 19, which rotates a pump of a hydraulic power unit 20, or if there are several pumps, as is well known, all of the pumps, for supplying hydraulic fluid through conduits 21 to 23 into the percussion machinery 2, the rotation motor 11 and the feed motor 7, of which the last- mentioned forms part of the feed system. The drilling machine 13 is displaced on the feed beam forwards, that is, towards the rock during the drilling by means of the feed motor 7. The connection of the feed motor 7 and the power transmission to the drilling machine 13 are known per se and obvious to one skill¬ ed in the art and therefore will not be described in more detail. The drilling equipment further comprises a control unit 24, which contains e.g. the adjusting means and devices shown in Figure 4, by means of which the drilling process is adjusted. The control unit 24 is connected by means of control conduits 25 to 27 to the hydraulic power unit so that each con- duit controls a specific operation as shown in Figure 4 for carrying out the method. Accordingly, for instance, the conduit 25 is arranged to control the percussion power to the percussion machinery 2, the conduit 26 is arranged to adjust the amount of hydraulic fluid to be supplied to the rotation motor 11 so as to adjust the rotation rate, and the conduit 27 is arranged to adjust the amount of hydraulic fluid to be supplied to the feed motor 7. Further, a control signal 28 is applied from the feed motor 7 to the control unit 24 in order to indicate the rate of travel of the drilling machine 13 with respect ' to the feed beam 16, that is, the drill penetration rate x, on the basis of which the optimization and adjustment of the drilling process are carried out as described above. The invention has been described and shown in the description above and the attached drawings only by way of example, and it is in no way restricted to this example. Drilling can be optimized in various ways, of which the optimization of the penetration rate is one of the most important in many cases. Another well known alternative is to calculate the cost of penetration per length unit while allowing for the other parameters and then adjust the drilling process so that the cost is minimized. In practice, however, the maximum penetration rate often cor¬ responds to the cost minimum on a certain percussion power level.

Claims: Claims: 1. A method of optimizing rock drilling, where¬ in a penetration rate (x) of a drill bit of a drilling machine into a rock is measured and the operating parameters (H f , H r ) of a drilling equipment are adjusted to maximize the penetration rate (x), c h a r a c t e r i z e d in that the operating parameters (Hf, H r ) are adjusted one at a time while the other operating parameters (H f , H r ) are kept sub¬ stantially constant, that a continuous deviation is caused to occur symmetrically on both sides of the set value of the operating parameter (Hf, H r ) to be adjusted, that a change caused by the deviation in the penetration rate (x) is measured, that when the change caused by the deviation in the penetration rate (x) is different on different sides of the set value, the set value is adjusted on the basis of the measurements in a direction in which the penetration rate (x) increases, and that when a maximum value of the penetration rate (x) is substantially achieved by adjusting one operating parameter (Hf, H r ), the oper¬ ating parameter (H f , H r ) to be adjusted is changed. 2. A method according to claim 1, c h a r a c - t e r i z e d in that the set value of the operating parameter (Hf, H r ) is deviated as a sinusoidal curve. 3. A method according to claim 1 or 2, c h a r¬ a c t e r i z e d in that the operating parameters (Hf, H r ) to be adjusted are the feed force of the drilling machine and the rotation rate of the drill bit, and that the percussion power of a percussion machinery is kept substantially constant. 4. A method according to any of the preceding claims, c h a r a c t e r i z e d in that a set value is given to each operating parameter (Hf, H__), and a deviation curve is combined with the set value during the adjustment so as to deviate said set value, that a change caused by the deviation in the penetration rate (x) is added to the set value so that when the set value deviates from a maximum value (x__„) of the penetration rate, the set value shifts automatically towards a set value corresponding to the maximum penetration rate (*« max ) while the other operating parameters (H f , H r ) remain substantially constant. 5. An equipment for realizing the method according to claim 1, comprising control devices for giving set values to a percussion machinery of a rock drilling equipment, a rotation rate of a drill bit and a feed force, and means for measuring a penetra¬ tion rate (x) of the drill bit, c h a r a c ¬ t e r i z e d in that the control devices comprise automatically operated adjusting means which deviate one operating parameter (H f , H r ) at a time from its set value, measure variation in the penetration rate (x), and shift the deviated set value in a direction in which the penetration rate (x) increases, said adjusting means changing the operating parameter (Hf, H r ) to be deviated when the set value being adjusted reaches a value substantially corresponding to a max¬ imum penetration rate (x). 6. An equipment according to claim 5, c h a r ¬ a c t e r i z e d in that the adjusting means com¬ prise control means (4, 8, 12) for deviating the set values for the feed force and the rotation rate of the drill bit one at a time. 7. An equipment according to claim 6, c h a r ¬ a c t e r i z e d in that it comprises separate control means (4; 8) for adjusting the set value of both the feed force and the rotation rate, that the means for measuring the penetration rate are arranged to control both control means, and that it comprises a separate change-over control (12) which alternately switches one of the control means (4, 8) into the deviation operation for adjusting the respective set value. [received by the International Bureau on 31 August 1992 (31.08.92); original claims 1-7 replaced by amended claims 1-7 (3 pages)] 1. A method of optimizing rock drilling, where¬ in a penetration rate (x) of a drill bit of a drilling machine into a rock is measured and the operating parameters (H f , H r ) of a drilling equipment are adjusted to maximize the penetration rate (__), whereby the operating parameters (H f , H r ) are adjusted one at a time while the other operating parameters (H f , H r ) are kept substantially constant, c h a r a c t e r i z e d in that a continuous deviation is caused to occur symmetrically on both sides of the set value of the operating parameter (H f , H r ) to be adjusted, that a change caused by the deviation in the penetration rate (x) is measured, that when the change caused by the deviation in the penetration rate (x) is different on different sides of the set value, the set value is adjusted on the basis of the measurements in a direction in which the penetration rate (_•_) increases, and that when a max¬ imum value of the penetration rate (£) is substan¬ tially achieved by adjusting one operating parameter (Hf, H r ), the operating parameter (H j , H r ) to be adjusted is changed. 2. A method according to claim 1, c h a r a c ¬ t e r i z e d in that the set value of the operating parameter (Hf, H r ) is deviated as a sinusoidal curve. 3. A method according to claim 1 or 2, c h a r¬ a c t e r i z e d in that the operating parameters (-_£, H r ) to be adjusted are the feed force of the drilling machine and the rotation rate of the drill bit, and that the percussion power of a percussion machinery is kept substantially constant. 4. A method according to any of the preceding claims, c h a r a c t e r i z e d in that a set value is given to each operating parameter (H f , H r ), and a deviation curve is combined with the set value during the adjustment so as to deviate said set value, that a change caused by the deviation in the penetration rate (x) is added to the set value so that when the set value deviates from a maximum value (x maχ ) of the penetration rate, the set value shifts automatically towards a set value corresponding to the maximum penetration rate (x max ) while the other operating parameters (H f , H r ) remain substantially constant. 5. An equipment for realizing the method according to claim 1, comprising control devices for giving set values to a percussion machinery of a rock drilling equipment, a rotation rate of a drill bit and a feed force, and means for measuring a penetra¬ tion rate (x) of the drill bit, whereby the control devices comprise automatically operated adjusting means which deviate one operating parameter (Hf, H r ) at a time from its set value, c h a r a c t e r i z ¬ e d in that the control device comprises means to measure variation in the penetration rate (it), and shift the deviated set value in a direction in which the penetration rate (x) increases, said adjusting means changing the operating parameter (Hf, H r ) to be deviated when the set value being adjusted reaches a value substantially corresponding to a maximum penetration rate ( ). 6. An equipment according to claim 5, c h a r - a c t e r i z e d in that the adjusting means com¬ prise control means (4, 8, 12) for deviating the set values for the feed force and the rotation rate of the drill bit one at a time. 7. .An equipment according to claim 6, c h a r - a c t e r i z e d in that it comprises separate control means (4; 8) for adjusting the set value of both the feed force and the rotation rate, that the means for measuring the penetration rate are arranged to control both control means, and that it comprises a separate change-over control (12) which alternately switches one of the control means (4, 8) into the deviation operation for adjusting the respective set value.

Inventors: MATTERO UNTO, MATTERO, UNTO
Applicants: TAMROCK OY
Application year: 1992
Main classification: E21B44
IPC codes: E21B19, E21B44