EP0199040B1 - Percussion bit for rock drills - Google Patents

Abstract

PCT No. PCT/DE86/00097 Sec. 371 Date Nov. 13, 1986 Sec. 102(e) Date Nov. 13, 1986 PCT Filed Mar. 8, 1986 PCT Pub. No. WO86/05542 PCT Pub. Date Sep. 25, 1986.Percussion drill bit for rock perforators is provided whose frontal face is covered by a plurality of hard-metal studs, whereby a plurality of studs are positioned to form a group, there being several of these groups present and each of the so-called groups being at a distance from one another at least circumferentially and separated through circulation-medium channels, and further provided with at least one axial center channel located roughly in a center of the frontal face and opening into the circulation-medium channels, characterized in that each group consists of only one row of studs (1) arranged on sloped protruding drilling facets (4), in that the drilling facets (4) run against the rotation direction (A) of the drill bit, at an angle with respect to the radius, and in that the circulation-medium channels (2) formed in the frontal face widen starting from the center of the drill bit, radially towards the outside.

Description

The invention relates to a percussion drill bit for rock drilling machines, the end face of which is covered with a large number of hard metal pins, several pins being combined to form a group, the groups thus formed being at least circumferentially spaced from one another and being separated from one another by fluid channels, and also as a fluid outlet at least one axial channel opening into the channels is provided, for example in the central region of the end face.

Such a drill bit is known for example from DE-A-27 33 300.

In this known, but two-part drill bit, cutting inserts, for example in the form of hard metal pins, are provided in groups, the groups being spaced apart from one another by means of fluid channels which run radially or are slightly curved in the direction of rotation.

However, the pins are arranged in a multiple arrangement on an island protruding from the fluid channels, so that larger chunks of cuttings can settle between the pins, which leads to a relatively long drilling time with appropriate propulsion, since these chunks first have to be ground down before they can pass through the fluid channels can be discharged to the outside through the fluid. The fluid channels are used for exhaust gas routing and do not support the removal of the cuttings, which removal is only through the Exhaust gas is caused. In addition, it is relatively difficult to regrind the pins arranged in this way, since the neighboring pins hinder each other from regrinding.
In order to fasten such drill bits to rock drilling machines, it is common in so-called countersink hammers to insert a grooved shaft into a receptacle, in which case the drive is designed to rotate to the left, or it can also be provided with external hole hammers, the shaft with an internal thread, which is then screw-connected to a threaded shaft , wherein this embodiment is then clockwise.

From DE-A-26 33 779 the individual arrangement of pins on projections protruding from the base body of the drill bit is known, although this arrangement enables easy regrinding of the pins, the transport of cuttings is impeded and larger chunks of cuttings are still between the individual Can fix pens.
From DE-A-2 007 520 a hammer drill bit for rock drilling machines is previously known, which has a large number of hard metal pins in the end face. Several pens are grouped together. The groups formed in this way are at least at a distance from one another in the circumferential direction and are separated from one another by fluid channels.

Furthermore, at least one axial channel opening into the fluid channels is provided as the fluid outlet, approximately in the central region of the end face.
In the case of the drill bit according to this prior art, larger chunks of cuttings are caught between the pins and have to be ground down first. Only when these constituents captured between the pins are ground small can they be at least partially transported away via the fluid channels with the support of the exhaust gas routing through central channels. With this arrangement, the drilling process itself is associated with a relatively large wear of the surfaces lying between the pins, which on the one hand leads to a longer drilling time and on the other hand to faster tool wear.
Based on this prior art, the invention has for its object to provide a hammer drill bit of the type described in the on the one hand there is a relatively simple possibility for regrinding, which on the other hand largely prevents larger chunks of cuttings from getting stuck between the pins and promotes the removal of the cuttings.

To solve this problem, it is proposed that the groups each consist only of a series of pins which are arranged on molded webs, and that the webs are rotated by an angle opposite to the direction of rotation of the drill bit relative to the radius of the drill bit intersecting the central axis of the webs .

This constructive measure makes it possible, on the one hand, to regrind the pins of each row of pins relatively easily, the areas of the pins which are essentially involved in the grinding of the rock being easily accessible. On the other hand, larger chunks of cuttings can practically no longer get stuck between the pins, but these chunks can be immediately discharged radially outwards through the fluid channels. The cuttings are transported into the free spaces between the webs and carried away by the exhaust gases from the rock drilling machine, in particular the hammer drill.

Because the webs are rotated by an angle opposite to the direction of rotation of the drill bit relative to the radius of the drill bit intersecting the central axis of the webs, the removal of the drill cuttings is supported by the rotary movement of the drill bit, since the drill cuttings also without the exhaust gases, solely by the rotation the drill bit is conveyed radially outwards.

It is particularly preferred that the webs are curved.

To further facilitate the removal of the cuttings, it is preferred that the fluid channels formed in the end face are designed to widen radially outward from the center of the crown.
It is also proposed that the end face be conical.

Alternatively or additionally, it can be provided that the end face is curved.

In a preferred development, it is proposed that channels are formed axially in the transition region between the end face and the shaft, into which the Fluid channels of the end face open.

For this purpose, the arrangement of axially extending channels in the transition region between the end face and the shaft is known, for example from DE-OS 26 33 779. However, the special arrangement of the channels is particularly advantageous since there is now excellent transport between the channels in the end face and the axially extending channels.

In a preferred development, it is proposed that the axial channels be displaced far into the crown body, partially crossing the front fluid channels and possibly partially crossing the webs.
The fact that the channels are moved as far as possible radially inward promotes particularly rapid removal of the cuttings. Overall, the design according to the invention brings a higher performance without greater wear, so that the same drilling depth is achieved in a shorter time with less wear than is possible in the prior art. There is also less stress on the pins. Even the better one Grinding of the pins, in particular by simple means, is advantageous, whereby the arrangement of the pins means that the cut should be provided on the flanks of the pins that lie on the web side edges. Because the cut is thus not arranged in a radial orientation, but rather as a secant or the like, there is no radial chisel edge on the re-ground pins, so that the reworked drill bit has a very low tendency to rattle, that is to say it generates only extremely low vibrations. This significantly reduces the risk of the pins breaking.

It is further preferred that cut-back teeth pointing axially away from the end face are integrally formed between the axial channels.

These cutting teeth grind backward rock, which is necessary and beneficial especially when pulling the drill bit out of a borehole.
Furthermore, it is advantageous in this regard that the rear incisors are arranged on a crown base which tapers laterally and radially inwards away from the end face.

It is particularly preferred that the radially outermost pin of each web is arranged on a crown part formed by a cutting tooth.
As a result, more support material is arranged under the respective outer pin during the advance of the drill bit, so that the latter is not so much at risk of breakage.
In addition, the arrangement of the conically widening axial channels and the cutting teeth reduces the so-called "propeller wear".

It is advantageous to provide that at most three, in particular two, pins are arranged on each web.

Embodiments of the invention are shown in the drawing and described in more detail below.

Fig. 1

eine erste, sehr einfache Ausführungsform einer Schlagbohrkrone in stark vereinfachter schematischer Darstellung;

Fig. 2

desgleichen in Draufsicht;

Fig. 3

eine Variante gemäß Figur 1 gesehen;

Fig. 4

die Variante gemäß Figur 2 gesehen;

Fig. 5

eine weitere vorteilhafte Variante gemäß Figur 1 gesehen und

Fig. 6

diese Variante in der Ansicht gemäß Figur 2.

It shows:

Fig. 1

a first, very simple embodiment of a percussion drill bit in a highly simplified schematic representation;

Fig. 2

likewise in plan view;

Fig. 3

seen a variant according to Figure 1;

Fig. 4

seen the variant of Figure 2;

Fig. 5

seen a further advantageous variant according to Figure 1 and

Fig. 6

this variant in the view according to FIG. 2.

In all embodiments, a percussion drill bit is shown, which is provided with a grooved shaft (not shown), so that each is a left-handed embodiment. The direction of rotation is indicated by the arrow A in FIGS. 2, 4 and 6. The percussion drill bit for rock drilling machines has a large number of hard metal pins 1 in the end face, several pins 1 being combined to form a group of pins. These groups are spaced from each other. They are spatially separated from one another by fluid channels. The fluid outlet for the exhaust gases from the drilling machine is approximately in the middle the end face an axial channel 3 opening into the channels 2 is provided.

The groups referred to above are each formed only from a series of pins 1 which are attached to molded webs 4. The webs 4 are arranged inclined to the radius against the direction of rotation A of the drill bit. The simplest embodiment is shown in Figures 1 and 2.
According to FIGS. 3 to 6, the webs 4 and the fluid channels 2 are both curved, the curvature running counter to the direction of rotation A of the drill bit. In all embodiments, the fluid channels 2 formed in the end face expand considerably radially outward from the center of the crown.
In the exemplary embodiment according to FIGS. 1 and 2, the end face of the percussion drill bit is designed in the shape of a truncated cone, whereas the end face in the exemplary embodiments according to FIGS. 3 to 6 is bulged outwards.

3 to 6 in the embodiments axially extending channels 6 are arranged in the transition area between the end face and shaft 5, into which the fluid channels 2 open. The axial channels 6 are shifted as far as possible into the body of the drill bit, partly crossing the front fluid channels 2, but partly also the webs 4 (in particular in the embodiment according to FIGS. 5 + 6).

In the exemplary embodiment according to FIGS. 5 and 6, cut-back teeth 7 are formed between the axial channels 6 on the outside axially pointing away from the end face. The rear incisors 7 are arranged on a crown base 8 tapering laterally and radially inward away from the end face. The radially outermost pin of each web 4 is arranged on a crown part formed by a cutting tooth 7.
Two pins 1 are preferably arranged on each web 4. Depending on the course and arrangement of the webs, it can also be advantageous to arrange three pins 1 or only one pin 1 on a web 4.

The design according to the invention achieves a high drilling performance with relatively little wear, and a long service life of the drill bit with low energy consumption, since the cuttings leave the bottom of the borehole much coarser.

Claims (11)

1. A hammer drill crown bit for stone boring machines, the front surface of which is provided with a plurality of hard metal studs, where in each case several studs are assembled in a group, there are gaps between the groups thus formed, at least in the circumferential direction, and they are separated from one another by channels for a flow medium, and furthermore an axial channel which opens into these channels is provided approximately in the middle region of the front surface as an outlet for the flow medium, characterized in that the groups in each case consist of only one row of studs (1), which are arranged on built-in lands (4), and in that the lands (4) are rotated through an angle relative to the radius of the crown bit which intersects the mid-axis of the land (4) in a direction opposite to the rotation of the crown bit.
2. A hammer drill crown bit as claimed in claim 1, characterized in that the lands (4) extend in a curve.
3. A hammer drill crown bit as claimed in one of claims 1 or 2, characterized in that the channels for a flow medium (2) formed in the front surface are constructed so that they widen from the centre of the crown to the outside in the radial direction.
4. A hammer drill crown bit as claimed in any one of claims 1 to 3, characterized in that the front surface is formed with a truncated cone shape (Figures 1 + 2).
5. A hammer drill crown bit as claimed in any one of claims 1 to 4, characterized in that the front surface is dome shaped (Figures 3 to 6).
6. A hammer drill crown bit as claimed in any one of claims 1 to 5, characterized in that in the transitional region between the front surface and the shaft (5) axial channels (6) are formed into which the channels for a flow medium (2) in the front surface open.
7. A hammer drill crown bit as claimed in any one of claims 1 to 6, characterized in that the axial channels (6) are displaced far into the body of the crown as a result of which they partially cut across the channels for a flow medium (2) in the front surface and optionally partially cut across the lands (4).
8. A hammer drill crown bit as claimed in any one of claims 1 to 7, characterized in that between the axial channels (6) back cutting teeth (7) are formed on the outside, directed axially away from the front surface.
9. A hammer drill crown bit as claimed in any one of claims 1 to 8, characterized in that the back cutting teeth (7) are located on individual bases (8) on the crown tapering laterally and radially inwards from the front surface.
10. A hammer drill crown bit as claimed in any one of claims 1 to 9, characterized in that the radially outermost stud (1) of each land (4) Is located on a part of the crown (e.g. 8) formed by a back cutting tooth (7).
11. A hammer drill crown bit as claimed in any one of claims 1 to 10, characterized in that on each land (4) there are at the most three, and in particular two, studs (1).

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