EP0563561A1 - Superimposing drilling bit - Google Patents

Abstract

A superimposing drilling bit, with a head (1) provided with carbide pins (3) or the like and a shank (2) carrying the head (1), the shank (2) having means (4) for the rotationally rigid connection to a driven inner rod string, and the drilling bit having at least one drilling-fluid line (5), can be improved in particular with regard to its maintenance, without dispensing with the directional accuracy and the cutting efficiency, by the head (1) having a plurality of recesses (6) distributed symmetrically over its periphery and by swivel crowns (7) being arranged in the recesses (6) in such a way that they come to lie inside the diameter of the drilling bit in the swung-in state and project beyond the diameter of the drilling bit to a predetermined extent in the swung-out state. <IMAGE>

Description

The present invention relates to a drill bit for overlay drilling with a head provided with hard metal pins or the like and a shaft carrying the head, the shaft having means for torsionally rigid connection to a driven inner pipe rod and wherein the drill bit has at least one flushing agent line.

For a variety of reasons, the trend and necessity in sewer and pipeline construction are increasingly increasing, from the open construction to the closed construction, which requires the use of ever new and powerful drilling methods and drilling tools. Here The Imloch hammer, which was originally designed for use in a quarry, is becoming increasingly important thanks to its excellent drilling performance and possible uses, even in extreme ground conditions.

Two different paths are used in the prior art for overlay drilling. On the one hand, drilling devices for overlay drilling are known, which are provided using a drilling fluid with an outer pipe string carrying a ring drill bit, an inner pipe string running in the outer pipe string and carrying a central full drill bit, and with a first rotary drive rotating the inner pipe string and a second rotary drive rotating the outer pipe string Both rods are mounted on a driven feed device (DE 29 24 393 C2). On the other hand, it is known to use eccentric drilling devices. A known eccentric drilling device is described in DE 30 24 102 C2. In this case, the eccentric drill bit is eccentrically clamped at the end of the outer pipe string in order to obtain a drilling diameter which is larger than the outer diameter of the outer pipe string. After releasing the tension, the eccentric drill bit with the inner pipe rod can be pulled back through the outer pipe rod.

In any case, a bore hole is produced during the overlay drilling, the diameter of which is larger than the outside diameter of the piping to be introduced. The piping is expediently designed as an outer pipe linkage of the respective drilling device, in the case of which the one described above as the first alternative Device the ring drill bit carried by the outer pipe rod is lost at least in the production of blind bores. In any case, the distance between the outer pipe string and the actual pipe head must always be kept relatively small in order to prevent premature escalation in the borehole wall. To discharge the cuttings, a suitable flushing agent such as air or a water / oil emulsion is discharged deep down - preferably through the inner pipe string. The drilling mud, consisting of cuttings and detergent, is flushed out of the borehole through the annular space between the inner pipe string and the outer pipe string.

Both of the above-mentioned alternative devices for overlay drilling, which have been described in more detail above, suffer from disadvantages in some respects, so that the concentric arrangement of ring and solid drill bits always shows a very high degree of wear, in particular of the ring drill bit. Furthermore, the - often lost - ring drill bits are expensive to manufacture, since extremely hard materials have to be used because it is no longer possible to replace them during drilling operations. When using eccentric drill bits, there are relatively large deviations in directional accuracy and only low cutting performance is possible.

The invention is therefore based on the object of designing and developing a drill bit of the type mentioned at the outset in such a way that the drill bit, in particular for replacement, is always removed from the borehole and a large overcut can nevertheless be achieved.

This object is achieved in that the head is symmetrical over a plurality Has circumferentially distributed recesses and that swivel bits are arranged in the recesses such that they come to lie within the drill bit diameter in the swiveled-in state and project in the swung-out state by a predetermined amount beyond the drill bit diameter. According to the invention it is achieved that the annular space required for the piping around the actual drill bit can also be drilled out by the pivoted-out swivel bits. Due to the pivotability, the entire drill bit with the swiveled-in swivel bits can still be removed from the borehole through the outer pipe string.

The solution according to the invention also has economic advantages, since the individual swivel bits - in contrast to the ring drill bit which can no longer be replaced - can be replaced quickly and easily. This possible reduction in tool life can result in considerable savings in material selection.

As already mentioned, the recesses for the swivel crowns are distributed symmetrically over the circumference of the head. It is advantageous that each swivel crown is provided with an eccentrically arranged shaft and that it has a plurality of receiving bores in the region of the recesses for receiving the shafts of the individual swivel crowns. Here again, it is expedient that the receiving bores and / or the swivel crowns have means for a mutual connection. This is particularly important because the drill bit with the swivel bits arranged on it must be recovered from the borehole. It has proven particularly beneficial if each Receiving hole in the drill bit has an annular groove and each swivel bit in the area of its shaft has a widening corresponding to the groove. In terms of production technology, it is particularly advantageous if the widening is designed as a spring ring arranged in the groove provided on the shaft of each swivel crown.

In order to be able to determine an exact predetermined drilling diameter, it is advantageous for the drill bit to have means for limiting the pivoted-out swivel crowns in the region of its recesses. In a further embodiment of the invention it is provided that the side walls delimiting the recess are provided as a means for limiting the pivoted-out swivel crowns. In this way, a secure stop is achieved for the swivel crown pivoted into the working position without additional design effort.

According to a further teaching of the invention, the flushing agent line branches off in the shaft of the drill bit to the individual recesses for the swivel bits. It has been found that it is not necessary to also provide the swivel crowns with their own detergent lines if the detergent lines end in the region of the individual recesses. It is advantageous here if the openings of the flushing agent lines are arranged in the recesses in such a way that they are covered by the swiveled-in swivel crowns. It is expedient if, according to a further embodiment of the invention, each recess has two rinsing bores which end in the central rinsing agent line located in the shaft and whose openings to the outside, ie are directed in the swivel direction of each swivel crown. In this embodiment according to the invention, not only is sufficient cooling of the drilling tool and flushing of the cuttings achieved, but the pressure of the flushing agent supports the pivoting out which is caused primarily by frictional engagement of the cutting attachments of the swivel crowns with the deepest hole in the borehole. In addition, the area of the recesses always remains free of drilling mud etc., so that the swivel crowns can be reliably pivoted into the recesses by rotating the inner boring bar by a small amount in the direction opposite to the drilling direction.

It is also advantageous that, in a further embodiment of the invention, the cutting surface of each swivel crown is chamfered in the region of the largest drilling diameter when the swivel crowns are swiveled out - that is to say in the edge region of the "enlarged" drilling diameter. This configuration has a favorable influence on the stress distribution in the borehole wall, so that unwanted extrusion can also be avoided.

Fig. 1

eine erfindungsgemäße Bohrkrone mit drei ausgeschwenkten Schwenkkronen in perspektivischer Ansicht,

Fig. 2

eine Aufsicht derselben Bohrkrone, wobei jedoch eine der drei Schwenkkronen im eingeschwenkten Zustand gezeigt ist,

Fig. 3

einen Längsschnitt durch die erfindungsgemäße Bohrkrone entlang der Linie III-III aus Figur 2 ohne Schwenkkronen,

Fig. 4

einen Schnitt durch die erfindungsgemäße Bohrkrone entlang der Linie IV-IV gemäß Figur 3 und

Fig. 5

einen Längsschnitt durch eine der zur erfindungsgemäßen Bohrkrone gehörenden Schwenkkronen.

The invention is explained in more detail below with the aid of a drawing illustrating an exemplary embodiment. Show in the drawing

Fig. 1

a drill bit according to the invention with three swiveled-out swivel bits in a perspective view,

Fig. 2

a top view of the same drill bit, but one of the three swivel bits is shown in the swiveled-in state,

Fig. 3

2 shows a longitudinal section through the drill bit according to the invention along the line III-III from FIG. 2 without swivel bits,

Fig. 4

a section through the drill bit according to the invention along the line IV-IV according to Figure 3 and

Fig. 5

a longitudinal section through one of the swivel bits belonging to the drill bit according to the invention.

The figures show a drill bit consisting primarily of a head 1 and a shaft 2 for overlay drilling. The head 1 of the drill bit according to the invention is provided with hard metal pins 3 in a known manner. The shaft 2 is connected in a rotationally rigid manner to a driven and not shown inner tube linkage, a recess 4 being indicated in FIG. 3.

In the interior of the drill bit according to the invention, a flushing agent line 5 runs through the shaft 2 and the head 1 and is supplied with flushing agent for flushing out the cuttings from a flushing agent line running in the inner pipe string.

According to the invention, the head 1 has a plurality of recesses 6 arranged symmetrically over its circumference. In the illustrated and in this respect preferred embodiment, three recesses 6 are provided, in which swivel crowns 7 are arranged such that they come to lie within the drill bit diameter in the swiveled-in state and in project the swung-out state by a predetermined amount beyond the drill bit diameter. While all three swivel crowns 7 are shown in the swung-out state in FIG. 1, one of the three swivel crowns 7 is shown in its position pivoted into the recess 6 in FIG. The embodiment shown relates to a small version of the drill bit according to the invention, in this case the drill head diameter is 88 mm, and in the swung-out state of the swivel crowns 7, drilling is carried out with an "enlarged" drill diameter of 124 mm. It is easy to see that larger versions allow a correspondingly higher number of swivel crowns 7.

In a further embodiment of the invention, each swivel crown 7 is provided with an eccentrically arranged shaft 8 and the drill bit in the region of its recesses 6 has a plurality of receiving bores 9 for receiving the shafts 8 of the individual swivel crowns 7, as can be seen particularly clearly from FIGS. 3 and 5 .

For a secure connection from the head 1 of the drill bit to the individual swivel crowns 7, the receiving bores and the swivel crowns 7 have means for a mutual connection. In the exemplary embodiment, each receiving bore 9 in the drill bit is provided with an annular groove 10 and each swivel bit 7 on its shaft 8 with a widening corresponding to the groove 10. It is expedient if the widening is designed as a spring ring 11 arranged in the groove 10 provided on the shaft 8. In order to ensure a defined swiveling out of the individual swivel crowns 7, as means for Limitation of the pivoted-out swivel crowns 7, the side walls 12 delimiting the recess 6 are provided, as can be seen particularly clearly from FIGS. 1 and 2. In the illustrated embodiment, the hard metal pins 3 are distributed symmetrically on the head 1 and the three swivel crowns 7. However, it may be advantageous to arrange the hard metal pins 3 asymmetrically, in particular on the swivel crowns. It is particularly expedient that each swivel crown 7 is provided with a bevelled cutting surface 14 in the region of the largest drilling diameter when the swivel crowns 7 are swiveled out, as can be seen from FIG.

Finally, it can be seen from the figures that the openings 13 of the detergent lines 5 are arranged in the recesses 6 in such a way that they are covered by the pivoted-in swivel crowns 7. In particular, FIG. 4 shows that each recess 6 has two flushing bores 5A and 5B, which end in the central flushing agent line 5 located in the shaft 2 and whose openings 13 point outwards, ie in the pivoting direction of each swivel crown 7. For this purpose, it is necessary that the flushing agent line 5 branches in the shaft 2 of the drill bit to the individual recesses 6 for the swivel bits 7, as can be clearly seen in FIG.

Evidence list

1

head

2nd

shaft

3rd

Tungsten carbide pin

4th

Recess

5

Detergent line

5A

Detergent line

5B

Detergent line

6

Recess

7

Swivel crown

8th

shaft

9

Location hole

10th

Groove

11

Spring washer

12

Side wall

13

opening

14

Cutting surface

Claims (11)

Drill bit for overlay drilling with a head provided with hard metal pins or the like and a shank supporting the head, the shank having means for torsionally rigid connection to a driven inner pipe linkage and the drill bit having at least one flushing agent line, characterized in that the head (1) has a plurality of recesses (6) distributed symmetrically over its circumference and that swivel crowns (7) are arranged in the recesses (6) in such a way that they come to lie within the drill bit diameter in the swiveled-in state and in the swung-out state by a predetermined amount over the drill bit diameter protrude. Drill bit according to claim 1, characterized in that each swivel bit (7) with an eccentrically arranged shaft (8) is provided and that the drill bit in the region of its recesses (6) has a plurality of receiving bores (9) for receiving the shanks (8) of the individual swivel bits (7). Drill bit according to claim 1 or 2, characterized in that the receiving bores (9) and / or the swivel bits (7) have means (10, 11) for a mutual connection. Drill bit according to claims 2 and 3, characterized in that each receiving bore (9) in the drill bit has an annular groove (10) and each swivel bit (7) on its shaft (8) has a widening corresponding to the groove (10). Drill bit according to claim 4, characterized in that the widening is designed as a spring ring (11) arranged in the groove (10) provided on the shaft (8). Drill bit according to one of claims 1 to 5, characterized in that the drill bit in the region of its recesses (6) has means for limiting the pivoted-out swivel bits (7). Drill bit according to claim 6, characterized in that the side walls (12) delimiting the recess (6) are provided as means for limiting the swiveled-out swivel bits (7). Drill bit according to one of claims 1 to 7, characterized in that the flushing agent line (5) branches in the shaft (2) of the drill bit to the individual recesses (6) for the swivel bits (7). Drill bit according to claim 8, characterized in that the openings (13) of the flushing agent lines (5) are arranged in the recesses (6) in such a way that they are covered by the swiveled-in swivel bits (7). Drill bit according to claim 8 or 9, characterized in that each recess (6) has two rinsing bores (5A, 5B) which end in the central rinsing agent line (5) located in the shaft (2) and whose openings (13) to the outside, ie point in the swivel direction of each swivel crown (7). Drill bit according to one of claims 1 to 10, characterized in that each swivel bit (7) is provided with a beveled cutting surface (14) in the area of the largest drilling diameter when the swivel bits (7) are swiveled out.

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