GB2181077A

GB2181077A - Controlling drilling tool

Info

Publication number: GB2181077A
Application number: GB08621655A
Authority: GB
Inventors: Veijo Nurmi
Original assignee: Tampella Oy AB
Current assignee: Tampella Oy AB
Priority date: 1985-09-30
Filing date: 1986-09-09
Publication date: 1987-04-15
Also published as: FI853760L; FR2588039B1; GB2181077B; NO863622D0; FR2588039A1; SE8603762D0; FI853760A0; SE8603762L; JPS6282197A; GB8621655D0; NO863622L; DE3630728C2; DE3630728A1

Abstract

In a method of controlling a drilling tool in rock drilling for automatic drilling of several adjacent holes, the drilling tool (2) is shifted from hole to hole along a shifting level (S) situated at a distance from the rock surface (1). In order to avoid unnecessary shifting movements of the drilling tool and to speed up the drilling, the drilling tool is shifted from one hole to another (R4, R5, R6) along shifting levels (S5, S6) defined individually for each hole. The shifting levels can be determined on the basis of a constant safety distance (C), a sensed location of the rock surface or an estimated form of the rock surface. <IMAGE>

Description

SPECIFICATION A method of controlling a drilling tool in rock drilling This invention relates to a method of controlling a drilling tool in rock drilling for automatic drilling of several adjacent holes, according to which method a drilling tool is shifted from hole to hole along a shifting level situated at a distance from a rock surface.

It is previously known to control a drilling tool, i.e. to shift a drilling tool from hole to hole automatically, when a tunnel is quarried by a drilling/blasting method, whereby in a space to be quarried is drilled a predetermined number of drill holes situated at a distance from each other, which holes are charged and blasted. By means of automatic drilling, it is possible to make the operation of a drilling equipment more effective and one man can handle a drilling equipment with many booms, when the holes are directed and drilled fully automatically according to a drilling plan drawn up in advance after the equipment has been set in its place.

U.S. Patent 4 113 033 discloses a drilling boom operating by programmable control and a method of shifting a drilling tool from one drill hole to another. In this method, the location of the holes is determined on an imaginary shifting level situated at a certain safety distance from the rock surface, to which level the drilling tool is brought back after a hole is ready-drilled and along which level the drilling tool is shifted to the next hole to be drilled.

In the method according to the U.S. Patent the level for shifting the drilling tool is common to all holes to be drilled. In practice, however, the rear of the tunnel is not straight, but curve-shaped. The more curved the rear of the tunnel is formed, the longer way the drilling tool has to return from the starting point of the hole to the shifting level, especially in the middle area of the rear of the tunnel. This again means that longer times are needed for shifting.

The object of this invention is to provide a method avoiding the disadvantage mentioned above and making it possible to increase the drilling rate and to intensify the operation of the equipment. This object is achieved by a method according to the invention, which method is characterized in that the drilling tool is shifted from one hole to another along shifting levels defined individually for each hole.

The invention is based on the idea that when the drilling tool is shifted from one hole to another the probable or actual shape of the rear of the tunnel is taken into account more accurately so that unnecessary safety distances can be avoided and the drilling tool can be shifted from hole to hole along the most appropriate shifting level in each particular case. By means of the method of the invention, it is possible to considerably shorten the time needed for returning the drilling tool to the shifting level required after a hole has been drilled, and respectively, for shifting the drilling tool from this shifting level towards the rock surface to the next hole to be drilled.

The method according to the invention can be realized in several different ways: 1. At all holes, a constant safety distance, i.e. an equal distance, can be used, to which distance the drilling tool is returned from the rock surface of a hole drilled, before it is shifted in lateral direction to the next hole to be drilled. At the moment when the drill bit touches the rock surface, the axial length of the drilling tool is recorded and after the hole has been drilled, the drill bit is shifted from the recorded contact point with the rock surface a set distance backwards and only after that in lateral direction to the next hole.

2. At separate holes, safety distances of different size can be used, to which the drilling tool is returned before it is shifted in lateral direction to the next hole. Then the distance between the contact levels of the previous hole and the hole to be drilled is measured and on the basis of this distance, a safety distance possibly needed is defined e.g.

in a certain relation to the distance between the contact levels or in another manner mathematically according to the curve formed by the starting points of several successive holes.

3. The safety distance of separate holes can be defined by measuring the distance of the rock surface by some suitable method. A constant safety distance is then normaliy used, to which the drilling tool is returned from the contact point with the rock surface, but when greater distance deviations appear, a greater safety distance is used, correspondingly.

4. The safety distance of separate holes can be calculated on the basis of the form of the rock surface by touching it at suitable points with the drill bit in order to define the mathematical form of the surface or to estimate the form of the rock surface on the basis of statistical knowledge and experience in quarrying.

The invention is explained more closely in the following with reference to the enclosed drawings, wherein Figure 1 schematically illustrates from above the method known from said U.S. Patent for the control of a drilling tool when quarrying the rear of a tunnel, Figure 2 shows in a corresponding manner a first embodiment of the method of the invention when a constant safety distance is used, Figure 3 shows a second embodiment of the method when a return distance based on the surface form is used, Figure 4 shows a third embodiment of the method when a distance based on statistical probability is used and Figure 5 shows two other embodiments of the method, where the shifting level of the drilling tool is in an oblique position with respect to the drill holes to speed up shifting.

When quarrying a tunnel in a rock, some predetermined number n of substantially parallel holes Ri-Rn are drilled in a space UVXY to be quarried, Figure 1, which holes are charged and blasted. According to the method suggested in U.S. Patent 4 113 033, the location of the holes is defined on an imaginary shifting level S situated at a certain distance from the rock surface 1, to which level a drilling tool 2 is returned after a drill hole is ready-drilled and along which level the drilling tool is shifted to the next hole. For instance, after a hole R3 has been drilled, the drilling tool is drawn a distance A3 axially back to the shifting level, shifted in lateral direction along the level S to next hole R4 and pushed axially forward a distance B4 into contact with the rock surface for drilling a new hole.After the hole R4 has been drilled, the drilling tool is again returned to the shifting level S etc.

The movements of the drilling tool occur automatically by the action of an automatic control of the drilling equipment starting from the shifting level S common for all holes.

in the methods visualized in the Figures 2-4, the drilling tool is shifted from hole to hole along levels defined individually for each hole.

In the embodiment of Figure 2, the drilling tool is after each hole returned to a safety distance C from the rock surface 1, which distance shall be maintained constant. A safety distance means a distance from a rock surface being either known, otherwise estimated or supposed either at a drilled hole or at a hole to be drilled. For instance, after the hole R4 has been drilled, the drilling tool is drawn the distance C axially back from the starting point 3 of the hole to a point 4 situated on its axial extension. This point defines a shifting level S5, which is perpendicular to the direction of the hole drilled. The drilling tool is shifted on this level to a point 5 situated on the axial extension of next hole R5 to be drilled, whereafter the drilling tool is shifted towards the rock surface, which it meets after a distance D5 at a starting point 6.The hole R5 is drilled in a normal way into a depth desired, whereafter the drilling tool is drawn out of the hole again to the same safety distance C from the rock surface. From this point the drilling tool is shifted along a shifting level S6 to next hole R6 to be drilled etc.

The constant safety distance C is chosen so great that the drilling tool for sure can shift along the shifting levels S without hitting against possible irregular projections on the rock surface. The constant safety distance remains the same, unless the operator wants to change it. In practice, the operator can always estimate the constant safety distance needed when starting drilling of a set of holes and adjust it constant in the control system for this set of holes.

It is noticed that the shifting distances of the drilling tool are considerably shorter than those in the prior art illustrated in Figure 1.

This speeds up substantially the drilling of the holes necessary for quarrying a tunnel.

In the embodiment of the method shown in Figure 3, the drilling tool is after each hole returned about a return distance E defined individually for each hole. The form of the rock surface is investigated by distance measuring before drilling holes so that the coordinate of depth at the starting point 3 of each hole is known. The return distance is now calculated automatically so, that the tool is returned just about such a distance E that the tool scarcely has place to move to the next hole to be drilled.

For instance, after the hole R4 has been drilled, the drilling tool is drawn a return distance E4 calculated in the manner explained axially backwards from the starting point 3 of the hole to the point 4 situated on its axial extension. The drilling tool is shifted in lateral direction along a shifting level S5 passing through this point to a point 5 situated on the axial extension of the next hole R5 to be drilled. The hole R5 is drilled in a normal way into a depth desired. After the hole has been drilled, the drilling tool is drawn out of the hole to such a small return distance E5 from the starting point of the hole that the drilling tool without obstacles can be shifted along a shifting level S6 to the next hole to be drilled.

It is noticed that the control of the movements of the drilling tool on the basis of the predetermined form of the rock surface makes it possible to maintain the return distance E at a minimum. Figure 3 illustrates by means of broken lines the use of a certain constant safety distance F in connection with this control method. This safety distance can then be considerably shorter than the estimated safety distance shown in connection with Figure 2.

In the embodiment shown in Figure 4, the return distance G of the drilling tool is determined individually for each hole on the basis of an estimated form of the rock surface.

When quarrying stone of a certain kind (strength, crackness etc.), the surface of the tunnel face is after blasting approximately similar. Then the formation of the rock surface is statistically known on the basis of previous drilling of similar rock surfaces and previous experiences in quarrying. The average form and the probable depth of the profile of the rock surface are thus known. This makes it possible to calculate a return distance, which with a certain probability is sufficient for shifting the drilling tool from one hole to another without the tool hitting against a projecting part of the rock surface. A probability of e.g.

90%, 95% or 99% can be chosen.

In Figure 4, the average form of the profile of the rock surface to be drilled is marked with a broken line P and the limit within which the rock surface with a 90% probability is situated is marked with a dotted line P-90.

For instance, after the hole R4 has been drilled, the drilling tool is drawn backwards from the starting point 3 to the point 4 a return distance G4 corresponding to the distance of the probability limit P-90 on the axial extension of the hole from the starting point 3 and further, a desired constant safety distance H to a point 4'. After this, the drilling tool is shifted on a transverse shifting level S5 passing through this point to the point 5 situated on the axial extension of the next hole R5 to be drilled. From this point the drilling tool is shifted towards the rock surface, which it meets after a distance J5 at the starting point of the hole R5. The hole R5 is drilled in a normal way, whereafter the drilling tool is returned to the constant safety distance H from the limit P-90 etc.

In Figure 5, two embodiments of the method of the invention are shown, whereby the drilling tool is shifted along a level being oblique with respect to the drilling direction from one drill hole to the following to shorten the time needed for shifting.

The first embodiment is based on the idea where the form of the rock surface is in a way predetermined e.g. by measuring or by some method mentioned previously in this application. The starting point of successive drill holes is then determined correspondingly and the shifting of the tool can be determined on the basis of the safety distance so that the tool, situated at the hole drilled at a safety distance from the starting point of the hole, is shifted directly to the next hole to be drilled, to a safety distance from the starting point determined for this hole.

According to Figure 5, after the hole 3 has been drilled, the tool is shifted to a distance E3' from the starting point of the hole R3.

After the starting point 3 of the hole R4 has been determined on the basis of the predetermined rock surface, the tool can be shifted from the safety distance E3' obliquely along a shifting level S4' to a safety distance E4' from the starting point 3 of the hole R4. After this again, the hole R4 can be drilled and the operation can be continued in a way desired or according to a schedule programmed in advance.

The second embodiment shown in Figure 5 is based on the idea that the tool can be safely shifted along a surface being oblique with respect to the drilling direction, when a minimum safety distance is attended to. After the hole R5 has been drilled, the tool is shifted, as shown when shifting from hole R5 to hole R6, to a socalled minimum safety distance C' from the starting point 6 of the hole R5. After this, the tool is shifted further outwards from the rock surface and simultaneously towards the axle of the hole R6, whereby the tool is moving along an oblique shifting level S6' so that when the tool comes to the axle of the hole R6 it has at the same time shifted from the starting point 6 of the hole R5 to the predetermined safety distance C.

By means of each embodiment of Figure 5, time is saved at the shifting of the tool, because the tool is shifted along a route as short as possible from one drill hole to another. Due to the form of the rock surface, the shifting levels are in these embodiments mostly oblique with respect to the drilling direction, but in some cases the shifting level can also be perpendicular to the drilling direction.

When a drilling as efficient and quick as possible is strived for, it is preferable to use on the left side of the middle line of the rock surface quarried in a normal way a method illustrated in Figure 5, according to which the tool is shifted from the safety distance of a hole drilled to the safety distance of next hole to be drilled, and respectively, on the right side an oblique shifting based on a minimum safety distance, whereby the shifting level most probably follows the common direction of the rock surface.

The drawings and the specification relating thereto are only intended to visualize the intention of the invention. As to the details, the method of the invention can vary within the scope of the claims.

Claims

1. Method of controlling a drilling tool in rock drilling for automatic drilling of several adjacent holes, according to which method a drilling tool (2) is shifted from hole to hole (R 1-Rn) along a shifting level (S) situated at a distance from a rock surface (1), characterized in that the drilling tool (2) is shifted from one hole to another (R3, R4, R5, R6) along shifting levels (S4', S5, S6, S6') defined individually for each hole.

2. Method according to claim 1, characterized in that after a hole (R3, R4, R5) has been drilled, the drilling tool (2) is drawn to a shifting level (S4', S5, S6') beginning at a safety distance (E3', C, C') from a starting point (3) of the drill hole.

3. Method according to claim 2, characterized in that the safety distance (C) is constant and that each shifting level (S5, S6) is substantially perpendicular to the drilling direction.

4. Method according to claim 2; characterized in that after the hole (R5) has been drilled, the drilling tool (2) is first drawn at least to a minimum safety distance (C') from the starting point (6) of the drill hole and that the drilling tool (2) thereafter is further drawn to a constant safety distance (C) from the starting point (6) of said drill hole and simultaneously shifted in lateral direction to a next hole (R6), whereby the shifting level (S6') beginning at the minimum safety distance (C') from the starting point of said drill hole is in an oblique position with respect to the drilling direction.

5. Method according to claim 1, characterized in that the location of the rock surface (1) at a drilling level is determined by distance measuring and that after the hole (R3, R4) has been drilled, the drilling tool (2) is drawn to a shifting level (S4', S5) situated at such a distance (E3', E4) from a starting point (3) of said drill hole, that the shifting level is tangent to the rock surface (1), increased with a desired safety distance (F) from this rock surface.

6. Method according to claim 5, characterized in that after the hole (R3) has been drilled, the drilling tool (2) is drawn at least to a safety distance (E3') from the starting point of the drill hole and that the drilling tool (2) is directly shifted along a shifting level (S4') beginning at the safety distance (E3') from the starting point of the drill hole to the next hole (R4) at a safety distance (E4') therefrom.

7. Method according to claim 6, characterized in that the shifting level (S4') is in an oblique position with respect to the drilling direction.

8. Method according to claim 1, characterized in that after the hole (R4) has been drilled, the drilling tool (2) is drawn to a shifting level (S5) situated at a distance (G4) from a starting point (3) of the drill hole which distance corresponds to an estimated form (P90) of the rock surface at the drilling level with a desired probability, increased with a desired safety distance (H).