EP0583629A1 - Core bit comprising removable toothed elements with a peripheral distribution - Google Patents

Abstract

Core bit, in particular for drill tubes, with an annular basic body (1) which can be welded to a drill tube or a coupling. Toothed elements (30) arranged in a peripherally distributed manner are attached to the basic body (1) by welding or by push-in connections in such a way that the surfaces for the fastening welds or the push-in connection faces lie on a plane circle relative to the bottom edge (18) of the basic body, the toothed elements having: a) a slightly curved connection face (31), adapted to the drill-tube diameter, for the connection to the bottom edge of the basic body; b) a virtually plane rear face (32) running at a right angle or an acute angle to this face; c) a continuously curved working face (33) which adjoins the connection face and the rear face, connects these faces, defines an angular range between about 180 DEG and 270 DEG and is provided with a number of embedded carbide end pins (29) or tips (28) distributed over the face and projecting by about 1.5 to 2.0 mm from the surrounding surface; d) two end faces (34) which terminate the above-mentioned faces on both sides and form an angle of less than 90 DEG to the connection face. <IMAGE>

Description

The invention relates to a drill bit with circumferentially distributed, detachably arranged tooth bodies, in particular for drill pipes.

Drill bits are known in particular for double-walled drill pipes with common diameters from 600 mm to 2000 mm. These consist of a cast steel body with crown teeth and a coupling part for connection to the drill pipe string. In the case of known drill bits, the teeth are formed by flame cutting from a rolled mild steel blank and are raised by welding and then armored with a wear overlay weld. With these crowns, the worn or broken teeth are rebuilt and armored and reground by so-called layer welding from bottom to top. If the wear-resistant armor is only to be partially replaced, the worn-out armor is first ground off, then the basic tooth shape is restored by means of weld-on and the wear-resistant armor is applied to it. This work can only be carried out on the construction site in exceptional cases; it also requires a workshop workload of approx. One to two working hours per tooth.

In other known drill bits, complete tooth units with outer cut-out cutters and inner tooth back are welded into the base body of the drill bit in deep bulges. This design means that very long and deep weld seams are required.

If worn teeth are to be replaced with this type of construction, it is cumbersome and lengthy to remove these large weld seams, to clear and prepare the bulges for receiving new tooth units. The welding of the new tooth units requires a lot of time and work. This extensive work cannot be carried out on the construction site either, but the drill pipes or drill bits have to be worked up in a workshop.

The invention relates to an improved drill bit, which can be easily detached from the drill pipe in a manner known per se and in which the tooth bodies exposed to the greatest wear and tear can be replaced with the least amount of time and effort. This work can be carried out on the construction site.

To solve this problem, an annular base body that can be welded to a drill pipe or a coupling has been proposed, on which spaced-apart tooth attachments are formed, on which the tooth bodies can be replaced by welding in such a way that all weld seams to the lower edge of the base body are on one flat circular line.

Instead of welding seams, plug connections or locks for the mechanical attachment of the tooth body can also be used come into consideration at the lower edge of the base body.

• a) einer dem Bohrrohrdurchmesser angepassten leicht gekrümmten Anschlussfläche für die Schweiss- oder Steckverbindung zu der auf einer ebenen Kreislinie liegenden Unterkante oder deren Zahn-Ansätzen des Grundkörpers,
• b) einer im rechten oder spitzen Winkel zu dieser Fläche verlaufenden nahezu ebenen Rückenfläche,
• c) einer an die Anschlussfläche und an die Rückenfläche anschliessende, diese verbindende, einen Winkelbereich zwischen ca. 180° und 270° umschreibende, stetig gekrümmte Arbeitsfläche, die flächenverteilt mit einer Anzahl von eingelassenen, etwa um 1,5 bis 2,0 mm aus der umgebenden Fläche heraustretenden Hartmetall-Stirnstiften versehen ist,
• d) zwei die obengenannten Flächen beidseitig abschliessenden Stirnflächen, die zu der Anschlussfläche einen Winkel kleiner 90° bilden.

The invention is based on this embodiment according to DE 39 33 867 A1, and it consists of a tooth body with

• a) a slightly curved connection surface adapted to the diameter of the drill pipe for the welded or plug-in connection to the lower edge lying on a flat circular line or its tooth attachments of the base body,
• b) an almost flat back surface running at a right or acute angle to this surface,
• c) a continuously curved work surface which adjoins the connecting surface and the back surface and connects them, circumscribing an angular range between approximately 180 ° and 270 °, which is distributed with a number of recessed surfaces of approximately 1.5 to 2.0 mm carbide end pins emerging from the surrounding surface are provided,
• d) two end faces which close off the abovementioned surfaces on both sides and form an angle of less than 90 ° to the connection surface.

• c') einer an die Anschlussfläche und an die Rückenfläche anschliessende, diese verbindende, einen Winkelbereich zwischen ca. 180° und 270° umschreibende, stetig gekrümmte Arbeitsfläche, in die eine Anzahl von Hartmetall-Platten eingelassen ist, die etwa um 1,5 bis 2,0 mm aus der gekrümmten Arbeitsfläche heraustreten.

A modified solution, which also starts from DE 39 33 867 A1, consists of a tooth body with the identical features a), b) and d), and with

• c ') a continuously curved, adjoining the connecting surface and the back surface, connecting these, circumscribing an angular range between approximately 180 ° and 270 ° Work surface in which a number of hard metal plates are embedded, which emerge from the curved work surface by approximately 1.5 to 2.0 mm.

This drill bit with the features designed according to the invention represents a significant advance over the known designs as well as the generic drill bit. While the drill pipes with the welded tooth bodies with hard metal pins shaped according to the generic state of the art are preferably suitable for cutting, even if they still have certain characteristics Having milling properties, the new design according to the invention is preferably suitable for milling use, although it also has good cutting properties; it can therefore be used more universally.

This also applies to known drill bits, for example according to DE 36 00 189 C2, which can mainly be used for milling driving. Furthermore, drill bits with cleat teeth are also used for milling in hard soils, in which the outer surfaces of the teeth run in the direction of the outer shell of the drill pipe and which have to protrude in order to achieve a free-cutting effect, so that only a milling track corresponding to the tooth width is produced.

When using these known drill bits, it has been shown that frequently, with varying soil conditions from very hard to stiff or solid plastic consistency, little or no progress in piping can be achieved. If the drill pipe is then to be pulled, the protruding teeth act like barbs; These known tooth shapes neither have a cut-back effect, nor do they have a cutting effect for the pipe feed in cohesive soils.

These disadvantages are largely avoided in the new configuration of the drill pipes with the tooth bodies. The end faces on both sides are inclined to form an acute angle with respect to the connection faces and sharp-edged with respect to the work surface describing an approximately oval circumferential line, so that a cutting-like contour is created. If, according to an additional feature, two inclined surfaces are connected to the cutting-like end faces, this clears a clearing space for the cut and loosened soil.

The service life of these cut edges is significantly increased if, according to a proposal, they are provided with welded-on armor made of a wear-resistant material. The end faces can also be armored over a large area and can also be reinforced with a hard metal plate.

An important feature is also that some of the tooth bodies are inclined outwards at an angle β between 5 ° and 25 ° and some tooth bodies are inclined inwards at an angle γ between 5 ° and 25 ° with the lower edge or their tooth attachments of the base body are connected, it being particularly advantageous if the tooth bodies are connected to the base body alternately inclined inwards and outwards.

This entanglement of the tooth body results in a sufficiently large pre-cut and free cut so that the drill pipes can be pulled at any time without difficulty or adapted to the progressing drilling process.

The shape of the tooth body - symmetrical to a tube-axial plane intersecting the tube axis - brings the extraordinary This has the advantage that the drilling can be carried out both rotating and oscillating, preferably alternately, without the drill pipe becoming stuck. A back milling as well as a cutting back effect is achieved at the same time via the tooth bodies that are inclined outwards, and the soil material leading to the lining is led away and removed inwards via the inclined surfaces and tooth gaps mentioned. Back milling is possible even with forage caused by rock deposits under the effect of the hard metal trim.

Further advantages can result from the fact that the greatest height of the toothed body, in relation to the lower edge of the base body, has alternately different masses. This results in different contact pressures of the individual tooth bodies on the drilling base to be milled, which makes it possible, for example, for individual rock inserts or chunks of hard rock to be pushed away more easily and then removed from the milling and cutting path during milling back. It is advantageous here that the outwardly inclined tooth bodies have a larger dimension, the inwardly inclined ones a smaller dimension of their greatest height: a step cut results when drilling, which enables very rapid piping progress.

The clearing away and displacement of loosened soil is also made easier by the fact that the lower edge of the base body has a slightly tapered cross-sectional taper towards the surfaces for the fastening weld seams. Furthermore, in the area of the cross-sectional taper, elevations serving as internal clearers can also be attached, which can be designed as weld-on hard armor or can be provided with weld-on hard armor.

The tooth bodies are expediently welded to the core bit body or to a plug connection to be releasably anchored in the core bit body in the region of their connecting surfaces and a adjoining surface section of their back surfaces. But the attachment of the tooth body by means of releasable locks can also be advantageous.

Another significant advantage of the drill bit according to the invention is that the semicircular basic shape of the milling track with its radius of curvature is also maintained in that the tooth bodies are alternately set, i.e. are arranged in different angular positions to the vertical.

According to further important features of the tooth body according to the invention, which is provided with hard metal plates, these plates are embedded in a tube-radial manner, ie perpendicular to the tube wall and thus perpendicular to the directions of movement of the tooth body, covering the entire curvature of the working surface. With good stability of the hard metal plates, this ensures a milling effect on the entire work surface lying in the drilling base.

It is advantageous for the milling property of the tooth body if the surfaces of the hard metal plates are beveled like a sawtooth, preferably one half each of the hard metal plates in one of the two directions of movement.

Fig. 1

einen Zahnkörper aus Richtung A gem. Fig. 2;

Fig. 2

einen Zahnkörper aus Richtung B gem. Fig. 1;

Fig. 3

einen Zahnkörper aus Richtung C gem. Fig. 2;

Fig. 4

einen Zahnkörper in Draufsicht gem. den Fig. 1 und 3;

Fig. 5

eine perspektivische Teilansicht von der Unterkante des Grundkörpers;

Fig. 6

einen Teilschnitt durch die Unterkante des Grundkörpers;

Fig. 7

einen anderen Teilschnitt durch die Unterkante des Grundkörpers;

Fig. 8

einen Schnitt durch einen Zahnkörper in einer anderen Ausführung;

Fig. 9

einen Zahnkörper aus Richtung A gem. Fig. 10;

Fig. 10

einen Zahnkörper aus Richtung B gem. Fig. 9;

Fig. 11

einen Zahnkörper aus Richtung C gem. Fig. 10.

The invention is described and explained below with its essential features using the exemplary embodiment shown in the drawing. Show it

Fig. 1

a tooth body from direction A acc. Fig. 2;

Fig. 2

a tooth body from direction B acc. Fig. 1;

Fig. 3

a tooth body from direction C acc. Fig. 2;

Fig. 4

a tooth body according to plan view. 1 and 3;

Fig. 5

a partial perspective view of the lower edge of the base body;

Fig. 6

a partial section through the lower edge of the base body;

Fig. 7

another partial section through the lower edge of the base body;

Fig. 8

a section through a tooth body in another embodiment;

Fig. 9

a tooth body from direction A acc. Fig. 10;

Fig. 10

a tooth body from direction B acc. Fig. 9;

Fig. 11

a tooth body from direction C acc. Fig. 10.

In Figure 1, the symmetrical, acute-angled position of the end faces 34 to the connection surface 31 is clear. The edges between the end faces 34 and the work surface 33, or the trapezoidal, adjoining the work surface 33, almost flat surface section 35 are hard-armored. A plurality of hard metal face pins 29 are fitted into the curved working surface 33.

Figure 2 shows the connection surface 31 and the back surface 32 as a throat for receiving the weld seam. The working surface 33, which is almost cylindrical in the form of a cylindrical part in its curved section, sweeps over an angle of 180 °, wherein it contains a plurality of hard metal end pins 29; its almost flat surface section 35 is at an obtuse angle to the connection surface 31. The inclined surface 36 cuts the end surface towards the back surface 32 in such a way that the end surface contour 37 is given a hook-like contour.

FIG. 3 illustrates the shape of the inclined surfaces 36: adjoining the back surface 32 and the part of the work surface 33 which abuts against it, and adjoining the end surfaces 34 on both sides, they are slightly concave.

FIG. 4 shows the concave course of the inclined surfaces 36 more clearly, recognizable by the course of the edge between the inclined surfaces 36 and the back surface 32. The shape of the connecting surface 31 shows the slight curvature of the tooth body adapted to the drill pipe diameter. The hard metal end pins 29 fitted into the work surface are visible with their part protruding beyond the outside of the tooth body.

FIG. 5 illustrates the attachment of the tooth bodies 30 to the lower edge 18 of the core bit body 1, as well as the position of the working surfaces 33 and the end surfaces 34 in their operative position. The base body 1 has a slightly conical cross-sectional taper 15 towards the lower edge 18.

Above the tooth bodies welded to a cross-section, raised areas serving as free-cut cutters and shaped according to their function are attached in this area.

The setting of the tooth bodies on the drill bit base body 1, and the resulting free cut in the drill base, is shown in FIGS. 6 and 7. The tooth body in FIG. 6, with inclined surface 36, almost flat surface section 35, end surface 34 and working surface 33 and the hard metal end pins 29 fitted therein, is inclined outwards by an angle β, the tooth body in FIG. 7 is inclined inwards by an angle. The attachment of the tooth body by means of a welded connection 14 to the tooth lugs 3 of the drill bit is made clear, as is the advantageous effect of the radial arrangement of the hard metal end pins 29 in the base of the drill. The difference in the greatest height of the tooth bodies h1 and h2, which is important for the cutting and milling properties, can also be seen in FIGS. 6 and 7.

In FIG. 8, the tooth body 30 is connected to the insertion shaft 13 by a welded connection 14. This is provided with a mounting hole 16 with which it can be detachably anchored in the base body 1.

FIGS. 9, 10 and 11 show an exemplary embodiment of the tooth body according to claim 2. This tooth body corresponds to that of FIGS. 1 to 4, four hard metal plates 28 being let into the working surface 33 instead of the hard metal face pins. Figure 10 illustrates their surface curvature adapted to the work surface curvature. As can be seen from FIGS. 9 and 11, two hard metal plates 28 are chamfered towards the two directions of movement of the tooth body.

Claims (19)

Drill bit with circumferentially distributed, detachably arranged tooth bodies, in particular for drill pipes, with an annular base body that can be welded to a drill pipe or a coupling, on which spaced-apart tooth attachments are formed, on which the tooth bodies are interchangeably attached by welding or by plug connections in such a way that the surfaces for the fastening weld seams or the plug connection surfaces to the lower edge of the base body lie on a flat circular line,
featured
by tooth body (30) with a) a slightly curved connection surface (31) adapted to the drill pipe diameter for the plug-in or welded connection (14) to the lower edge (18) lying on a flat circular line or its tooth attachments (3) of the base body (1), b) an almost flat back surface (32) running at right or acute angle (α) to this surface (31), c) a continuously curved work surface (33), which connects to the connection surface (31) and to the back surface (32) and connects these, circumscribing an angular range between approximately 180 ° and 270 °, which is distributed over a surface area with a number of recessed, approximately by 1.5 to 2.0 mm carbide end pins (29) emerging from the surrounding surface are provided, d) two end surfaces (34) closing the above-mentioned surfaces (31, 32, 33) on both sides, which form an angle of less than 90 ° to the connection surface (31). Drill bit with circumferentially distributed, detachably arranged tooth bodies, in particular for drill pipes, with an annular base body that can be welded to a drill pipe or a coupling, on which spaced-apart tooth attachments are formed, on which the tooth bodies are interchangeably attached by welding or by plug connections, that the surfaces for the fastening weld seams or the plug connection surfaces to the lower edge of the base body lie on a flat circular line,
featured
by tooth body (30) with a) a slightly curved connecting surface (31) adapted to the drill pipe diameter for the plug-in or welded connection (14) to the lower edge (18) lying on a flat circular line or its tooth attachments (3) of the base body (1), b) an almost flat back surface (32) running at right or acute angle (α) to this surface (31), c) a continuously curved working surface (33), which connects the connecting surface (31) and the back surface (32) and connects it, circumscribing an angular range between approximately 180 ° and 270 °, into which a number of hard metal plates (28 ) are inserted, which emerge from the curved work surface (33) by approximately 1.5 to 2.0 mm, d) two end surfaces (34) closing the above-mentioned surfaces (31, 32, 33) on both sides, which form an angle of less than 90 ° to the connection surface (31). Drill bit according to one of claims 1 or 2, characterized in that between the continuously curved working surface (33) circumscribing an angular range between approximately 180 ° and 270 °, with hard metal end pins (29) or hard metal plates (28) and the Connection surface (31) an almost flat surface section (35) is switched on, which is at an angle between 130 ° and 150 °. Drill bit according to one of claims 1 or 2, characterized by tooth bodies (30), in which two inclined surfaces (36) adjoin the back surface (32) and the work surface (33) adjoining it, and on both sides the end surfaces (34) cut the end faces (34) towards the back face (32) in a slightly concave manner such that the end face outlines (37) have a hook-like contour. Drill bit according to one of claims 1 or 2, characterized in that the tooth body (30) to the lower edge (18) the base body (1) or on their tooth attachments (3) with their connecting surfaces (31) are connected by releasable locks. Drill bit according to one of claims 1 or 2, characterized in that the tooth bodies (30) are welded to their lower edge (18) or their tooth attachments (3) in the region of their connecting surfaces (31) and a connecting surface section of their back surfaces (32) . Drill bit according to one of claims 1 or 2, and at least one of the following claims, characterized in that some of the tooth bodies (30) at an angle (γ) between 5 ° and 25 ° inwards and some tooth bodies (30) at an angle ( β) between 5 ° and 25 ° inclined outwards are connected to the lower edge (18) or the tooth extensions (3) of the base body (1). Drill bit according to claim 7, characterized in that the tooth bodies (30) are connected to the base body (1) alternately inclined inwards and outwards. Drill bit according to claims 1 and 3 or 2 and 3, characterized in that at least one of the edges between the end faces (34) and the back surface (32) is provided with hard welded armor going over to the work surface (33). Drill bit according to claims 1 and 3 or 2 and 3, characterized in that at least one of the end faces (34) is provided with hard welded armor over a large area. Drill bit according to claims 1 and 3 or 2 and 3, characterized in that at least one of the end faces (34) is reinforced with a hard metal plate. Drill bit according to one of claims 1 or 2, characterized in that the greatest height of the tooth body (30), in relation to the lower edge (18) of the base body, has alternately different masses (h1 / h2). Drill bit according to claims 7 and 12, characterized in that the greatest height (h1) of the inwardly inclined tooth bodies (30) is in each case less than the greatest height (h2) of the outwardly inclined tooth bodies (30). Drill bit according to one of claims 1 or 2, characterized in that the lower edge (18) of the base body (1) has a slightly conical cross-sectional taper (15) towards the surfaces for the fastening weld seams. Drill bit according to claim 14, characterized in that in the area of the cross-sectional taper (15) there are raised portions serving as internal clearers (10). Drill bit according to claim 15, characterized in that the internal clearers (10) are designed as weld-on hard armor. Drill bit according to claim 2, characterized in that the hard metal plates (28) are embedded in the pipe-radially over the entire curvature of the working surface (33). Drill bit according to claim 2, characterized in that the surfaces of the hard metal plates (28) are beveled in a sawtooth manner. Drill bit according to claim 18, characterized in that half of the hard metal plates (28) are beveled in the manner of a sawtooth in the direction of one of the two directions of movement of the tooth bodies (30).

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