KR20080052575A - A one-piece drill bit for single-pass anchor bolting and single pass drilling apparatus - Google Patents

Abstract

The present invention relates to a drill bit (16) and a single pass drilling apparatus (10). The one-piece drill bit (16) has a connection portion, adapted to be rigidly connected to a drill steel, a pilot part (14) and a reamer part (19). The pilot part has first rock machining means (17). The reamer part has a first center line (CL2) and second rock machining means (18A, 18B, 18C). The second rock machining means is provided axially between said connection portion and said first rock machining means and to one side of the pilot part. The drill bit has a rotational direction (R). A side of the pilot part (14) facing away from the reamer part (19) is provided with a wear resistant means (17'). The wear resistant means 17' is integral with the first rock machining means 17.

Description

ONE-PIECE DRILL BIT FOR SINGLE-PASS ANCHOR BOLTING AND SINGLE PASS DRILLING APPARATUS}

The present invention relates to a drill bit and a single pass drill apparatus according to the preamble of the independent claim.

Installation of anchor bolts to strengthen the excavation usually takes place in two separate steps. Generally, after drilling and removing the drill steel and bits, bolts are inserted into the holes and tightened or grouted. Single pass anchor bolting involves performing these two steps simultaneously, eliminating the need to remove the drill steel to insert the bolts. Advantages of single pass bolting include minimizing the time required for bolt installation, improving the safety of the drill device operator and increasing the possibility of complete automation of the process compared to manual or semi-manual bolting. Another advantage is the improved quality and precision of anchor bolt installation compared to manual or semi-manual bolting. The diameter of the hole is very important for the anchor bolt performance in the case of friction, for example split set bolts. Another advantage of single pass bolting is that the hole cannot collapse when the drill is removed because the bolt is already in the hole. Since the bolt is always installed, i.e. there is no loss of holes, this leads to greater efficiency.

The conventional approach to single pass bolting aims at an innovative anchor bolt that also acts as a drill steel with a drill bit provided around its end. Such devices are used via rotary drilling or rotary / impact drilling and are generally not suitable for hard ground conditions. Vibration anchor bolts, which are used on hard ground and do not reuse drill bits, are costly. Various loop bolts exist, a particular type of which is tubular (eg, split set, Swellex, etc.) with a central hole formed longitudinally through the bolt. Drill bits suitable for pulling through the case are complex and expensive. The use of special anchor bolts and the exclusive use of complex retractable bits make the cost competitive of the drilling speed against the cost of the bit worse than conventional single pass anchor bolts. Nevertheless, the installation benefits of self-drilling loop bolts are often more important than the non-self drilling type.

The drill bit according to the invention aims to substantially overcome or at least provide an alternative to the above problems associated with the prior art.

Another object of the present invention is to provide a single pass drill bit.

It is yet another object of the present invention to provide a lower cost of use drill bit and single pass drill device, making the use of single pass bolting more efficient in the mining industry.

Another object of the present invention is to provide a drill bit having good wear resistance.

In the specification, the word "comprises" or "comprising", unless stated otherwise, means to include the described integer or population of integers, but to exclude other integers or groups of other integers. It doesn't.

The accompanying drawings show embodiments of the invention of the kind described above. The details of the description in conjunction with the drawings do not obscure the generality of the foregoing broad description.

1A-1G schematically illustrate the sequence of single pass loop bolting using a drill bit in accordance with the present invention.

2A is a side view illustrating the drill bit and rod portion according to the present invention.

2B is a front view illustrating the drill bit.

3A is a side view showing a drill bit being punched in a rock.

3B is a front view showing a drill bit being punched in a rock.

1A to 1G show a single pass drill apparatus 10 according to the invention using a drill bit 16 according to the invention, and FIGS. 2A to 3B further show a drill bit 16 according to the invention. Shown in detail. The single-pass drill apparatus 10 is, for example, several pieces of long drill steel 11 and the like having a leading end 12 and a trailing end (not shown) in the drill direction F. FIG. Include the part. Leading end 12 has a connection including a screw 15, taper or bayonet connection (not shown). The integral drill bit 16 has rock processing means 17, 18A, 18B, 18C. The drill bit 16 may be connected to the drill steel via a connection 20 including a screw, taper or bayonet connection (not shown). The drill steel 11 and the drill bit constitute a drill means. The single pass drill apparatus 10 further comprises an anchor bolt 21 adapted to at least partially surround the drill steel 11. The anchor bolt 21 has an open end. The largest radial size of the drill bit is smaller than the smallest diameter of the anchor bolt 21.

The basic idea of a single pass drill apparatus 10 is to drill a hole with the bolt surrounding the drill steel, and then pull out the bit for use again. There is no loss of bit parts. The single pass drill apparatus 10 is disclosed in more detail in Swedish Patent Application No. 0400597-1, which is hereby incorporated by reference.

Drill bit 16 may be configured as follows with reference to FIGS. 2A and 2B. The integral drill bit 16 has a pilot portion 14 and a reamer portion 19 having a length, ie length L, sufficient to adequately guide the two integral portions, ie the entire apparatus 10. The center line CL1 of the pilot portion 14 forms a second angle α that is an acute angle with the axis CL3 extending parallel to the first center line CL2 of the reamer portion. The angle α is from -20 ° to + 20 °, excluding 0 °, preferably at least + 0.1 ° and at most + 15 °, and is shown in FIG. 2A and 3A with "+" exponent. Center line CL1 substantially coincides with the axis of hole 22 during drilling. Further, the center line CL1 of the pilot portion 14 substantially coincides with the centerline of the anchor bolt 21 during drilling, but not during retraction of the drill bit. The centerline CL2 of the reamer portion 19 and the centerline of the drill steel 11 coincide with each other when no drilling is performed. It should be noted that the pilot portion 14 and the reamer portion 19 need not be circular or symmetrical in radial section, so that the lines CL1 and CL2 can be understood as the average centerline in each part. do.

The integral rock drill bit 16 comprises a body 25 and a cemented carbide means, i.e. a chisel and / or buttons 17, 18A, 18B, 18C. The body of the drill bit is made of steel. The main body 25 includes a substantially cylindrical pilot portion 14 and a substantially conical reamer portion 19. The pilot portion 14 may have a conical shape, and the reamer portion 19 may have a cylindrical shape. The pilot portion has a front face that includes a chisel 17 extending in the radial direction or two or more front buttons (not shown) substantially aligned in the radial direction. The reamer 19 may have a circular radial cross section. The reamer has a front face that includes one or more front buttons, here three front buttons 18A, 18B, 18C. The front face may be convex or substantially planar. The buttons 18A, 18B, 18C may be arranged arcuately around the reamer. The buttons 18A, 18B, 18C may project slightly out of the outer periphery of the reamer to drill holes 22 having a larger diameter than the steel body 25 during drilling. The number of cemented carbide buttons in the reamer can be varied depending on how large the diameter of the drill bit is. In the area between adjacent reamer buttons, a chip passage or groove may be provided through which flush media can pass. The rock drill bit 16 is connected to the drill steel 11 by a connection, which transmits rotational motion and impact in a general manner. The drill steel 11 includes a channel for carrying the flush medium. The main channel of the flush medium is provided inside the drill bit. The front end of the main channel is connected with a plurality of branch channels exiting from the front face. The flush medium will actually be water, cement, or air. The pilot portion drills a pilot hole 22A having a smaller diameter and length with respect to the hole 22. The length L of the pilot portion 14 is determined by the distance in the direction parallel to the reamer portion centerline CL2 between the foremost portion of the pilot portion and the foremost reamer button 18A, 18B, or 18C. The length L is at least 10 mm and not more than 60 mm, providing a good service life and good guidance for the drill bit. The reamer button of this embodiment includes the leading button 18A, the middle button 18B, and the subsequent button 18C. During drilling, the largest reaction force in the reamer 19 acts on the leading and intermediate rock processing means 18A, 18B. Thus, the axial plane passing through the chisel 17 is inclined to pass between the leading and intermediate rock processing means 18A, 18B. In other words, the imaginary line S, which is preferably a centerline passing through the rock processing means or chisel 17 and perpendicular to the centerline CL2 of the reamer portion 19, is perpendicular to the vertical line N with respect to the centerline CL2 and A first angle β that is an acute angle is formed. The vertical line N intersects the rock processing means or the button 18A which is at the foremost in the direction of rotation R of the drill bit 16. It is preferable that angle (beta) is 0 degrees or more and 20 degrees or less. If the leading rock processing means in the reamer portion 19 is a button, the vertical line N crosses its center line. If the leading rock processing means in the reamer portion 19 has a different shape, the vertical line N crosses its foremost point in the direction of rotation R. As shown in FIG. During drilling, the greatest reaction force in the reamer 19 acts on the leading and intermediate buttons 18A, 18B. The rock processing means 17 extends at least to the outer surface 50, among others. Thus, by placing the rock processing means 17 on the outer surface 50 of the pilot portion in a specific relation to the leading button 18A, the rock processing means 17 wear-resistant at the portion of the reamer portion that receives the most wear during drilling. To form the means 17 '. Thus, the wear resistant means 17 ′ is integral with the first rock processing means 17. The tangent T, which is in contact with the outer surface 50 or the skirt portion 51 of the drill bit and parallel to the center line CL2, forms a radial distance X with the outer circumference of the front end of the pilot portion. The distance X is not zero and is preferably -5 mm or more and +5 mm or less.

This shape provides good drilling results and a better contact surface between the pilot hole 22A and the pilot portion 14. By inclining the pilot portion at an angle toward the reamer portion, a better drilling result is obtained because the drill steel always bends in the same direction at the time of drilling, and the bending of the drill steel 11 is carried out by the buttons 18A, 18B, 18C. Is limited by the contact at the axial lower end 52 of the skirt portion 51 below the axial direction. The lower end 52 of the skirt portion in contact with the rock may be harder than the rest of the steel body 25 by surface treatment or may have a rigid insert to reduce wear.

A single pass rock bolt device 10 is shown in FIGS. 1A-1G. 3A and 3B correspond to, for example, FIG. 1C. The bending angle of the drill steel 11 is exaggerated in FIG. 3A. The drill bit 16 is connected to the drill steel 11 by, for example, a screw. A drill machine, such as a standard drill jumbo, holds the drill steel. The bolt 21 is preferably supplied automatically around the drill steel and positioned behind the drill bit 16 in the drill direction F. In FIG. 1A, the pilot portion 14 first comes into contact with the rock and then processes the rock surface during circular interpolation for a while. Then, the pilot section 14 finds its exact center and starts to drill centrally, and at the same time, the drill steel 11 starts to swing with respect to the pilot section center line CL1 (see FIG. 1B). Then, the reamer portion 19 comes into contact with the rock surface and starts to widen the hole made by the pilot portion 14. After a while, the bolt 21 reaches the hole and is pushed into the hole as shown in Fig. 1C. In general, the bolt 21 is axially spaced from the drill bit 16. It is preferable that the diameter of the bolt 21 is smaller than the diameter of the hole 22. The drill bit 16 continues drilling to widen the hole 22 and the bolt is pushed forward by the connecting sleeve 26 of the drill machine until the transfer of the different parts stops (see FIG. 1D). The depth of the hole 22 is substantially determined by the length of the bolt 21, in other words, the feed stops when the washer 23 located at the subsequent end of the bolt reaches the rock face or the inlet of the hole (FIG. See 1E). The drill machine has an anchor bolt presser. The bolt presser is a connecting sleeve 26 or dolly tool driven by a drill steel. Dolly tools usually rotate with drill steel and bolts during insertion. However, for example in the case of mechanical anchor bolts, the bolts can be kept from rotating during insertion. The dolly tool can rotate the anchor bolt when fully inserted. The dolly tool also slides along the drill steel, making it easier to install mechanical shell bolts and grouted bolts. 1E shows the anchor bolt 21 fully inserted with the drill steel and the drill bit in the anchor bolt. The pressurizer pushes the plate to the rock surface. The washer may be a loose conventional plate having a central hole that cooperates with a bulge 24 at the subsequent end of the bolt. The drill bit then retracts from the pilot hole 22A (see FIG. 1F). The axial spacing between the bolt and the drill bit is greater than the depth of the pilot bore 22A, so that the leading end of the bolt does not interfere with the retraction of the drill bit. The drill bit and drill steel can be completely retracted and reused in repeated drill operations.

The machine driving the device 10 can be a tower hammer drill machine, a pure spinning machine, or a down-the-hole device.

The drill bit according to the present invention has good wear resistance because wear on the side facing away from the reamer is received by the wear-resistant rock processing means 17 ', and provides good drill results.

It is to be understood that the invention described herein is capable of modifications, improvements, and / or additions from those described in detail, and that the invention includes such modifications, improvements, and / or additions within the scope of the claims. .

Claims (10)

Integral drill bits configured for single pass anchor bolts, The drill bit 16 has a connecting portion, a pilot portion 14, and a reamer portion 19 that are firmly connected to the drill steel, the pilot portion having a first rock processing means 17, the reamer portion having a first center line. CL2 and second rock processing means 18A, 18B, 18C, wherein the second rock processing means is provided axially between the connecting portion and the first rock processing means on one side of the pilot portion, and the drill The bit has a direction of rotation R, On the side of the pilot portion 14 facing away from the reamer portion 19, there is a wear resistant means 17 ', which is integrally formed with the first rock processing means 17. Drill bit. The imaginary line (S) of claim 1 extending through the first rock processing means (17) and perpendicular to the first center line (CL2) of the reamer portion (19) is perpendicular to the first center line ( A first angle β which is an acute angle with N), wherein the vertical line N traverses the leading rock processing means 18A which is first in the direction of rotation R of the drill bit 16. Drill bit. 3. The drill bit as set forth in claim 2, wherein said first angle (β) is greater than 0 degrees and less than 20 degrees. 4. The drill bit according to claim 2 or 3, wherein the leading rock processing means (18A) in the reamer portion (19) is a button, and the vertical line (N) crosses its center line. 4. The drill bit according to claim 2 or 3, wherein the vertical line (N) crosses the foremost point of the leading rock processing means in the direction of rotation (R). 4. Drill bit according to claim 2 or 3, characterized in that the first rock processing means is a chisel (17) and the second rock processing means is at least three buttons (18A, 18B, 18C). The second angle α according to any one of claims 1 to 6, wherein the center line CL1 of the pilot portion 14 is an acute angle with the axis CL3 extending parallel to the first center line CL2. Drill bit). 8. A drill bit as claimed in claim 7, wherein the second angle (α) is from -20 ° to + 20 ° except for 0 °. 9. The length L of the pilot portion 14 is between the foremost portion of the pilot portion and the foremost second rock processing means 18A, 18B, or 18C. It is determined by the distance in the direction parallel to 1 center line CL2, The said length L is 10 mm or more and 60 mm or less, The drill bit characterized by the above-mentioned. A single pass drill device comprising a drill means and an anchor bolt 21, The device according to claim 1, wherein the drill device comprises an integral drill bit (16) according to claim 1.

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