SE429888B - MOUNTAIN DRILL WITH PROJECT DRILL HEAD - Google Patents

Description

15 20 25 30 35 40 7812674-5 height. The protruding tip should allow a good centering of the drill. In addition, due to the special location of the inner pins, the different distances relative to the drill bit tip and the mutually varying height, a separate cutting path is achieved for each inner pin.

As a result, high drilling feed is achieved. However, the inconvenience of these known drills has the effect that at a drilling diameter of more than 65 mm the drill runs very unstable. This instability is due to the varying distance between the cemented carbide pins and the drill bit tip.

If the eccentric pin placement is eliminated by arranging at least two cemented carbide pins on each cutting path, the uneven passage is admittedly eliminated, but on the other hand the feed is also reduced. Furthermore, tools made in this way are quite expensive.

The object of the present invention is to provide a rock drill with such a constructive design that even at larger drilling diameters of, for example, 80 mm and more, satisfactory centricity and high feed of the drilling tool are ensured.

This task is solved by a rock drill in accordance with the characteristic combination included in the characterizing part of claim 1.

Such a drill is initially centered with the cemented carbide pins arranged in the drill head top. Only then does the outer shard edge, which is equipped with two or more cemented carbide pins, come into contact with the rock and the stone material, respectively. This ensures an exactly centric run of the drilling tool. The inner pins arranged at different distances from the drill head tip, each of which describes its own cutting path, reach the stone material only when the drill is centered and the outer inserts have begun to work. Since the pins of the outer cutting edges through their centric device also ensure an exact centric passage of the drill, this can no longer be jeopardized by the eccentrically arranged inner pins starting to work.

An advantage of such a drill compared to previously known drills with drill bit tip and cutting vanes projecting therefrom consists in that each cemented carbide pin on the inner cutting surface between the drill bit tip and the outer cutting edge describes its own cutting path. that despite a large drilling radius, a good centricity is achieved at high drill feed. With the inner cutting surface lying between the drill bit tip and the outer cutting edges, as in hitherto known, similarly built drills, it is achieved that the stone material is not broken off into large pieces but through the eccentrically placed inner pins is harvested uniformly with high drill feed.

Advantageously, both the cemented carbide pins on the outer shear edge and those in the drill bit tip, which are arranged at the same distance from the center, form an angle of 300 with the drill shaft.

The invention will now be explained in more detail in connection with exemplary embodiments of the object of application shown in the accompanying drawing. Fig. 1 shows a cross section through the drill head according to the invention, Fig. 2 a top view of the drill head according to Fig. 1, Fig. 3 a special embodiment of the drill bit tip and Fig. 4 a section IV-IV according to Fig. 2.

Fig. 1 shows the drill head 1, which consists of outer cutting edges 3, equipped with carbide pins 4 and 4, respectively, arranged obliquely relative to the drill shaft. 4 ', of inner cutting surfaces 2 with eccentrically arranged pins 5 resp. 5 'and of a drill bit tip 8, where at least one pin 6 is centrally arranged. It is particularly advantageous if the cutting surface 9 of the drill bit tip 8 and the cutting surfaces 10 of the cutting edge edges form an angle of 600 with the drill bit axis and if the cutting surfaces 9 and 10 lie on the same cantilever. The cemented carbide pins 4, 4 'are inclined 300 relative to the drill shaft.

The drill head is designed in such a way that in the drilling direction the cemented carbide pin 6 projects outside the carbide pins 7 and 7 'standing obliquely relative to the drill shaft axis, which in turn project outside the outer cutting edges 3 with the pins 4 and 4 thereon, respectively. 4 '. Only in an underlying plane is the inner cutting surface 2 with the eccentrically arranged cemented carbide pins 5 resp. 5 '.

Fig. 2 shows in particular the location of the cutting edge 3.

Adjacent shards form an angle of 105 resp. l0 7812674-5 750. The shear device is symmetrical with respect to section III-III.

The drill bit tip 8 is, as also shown in Fig. 3, equipped with three cemented carbide pins lying in the same plane III-III. The two outer carbide pins 7 resp. 7 'has the same distance from the center of the drill and is inclined 300 relative to the drill shaft. Advantageously, the drill bit tip and the cemented carbide pins located thereon are arranged so that a plane extending through them simultaneously halves the angle between two cutting blades.

Fig. 4 shows a section 11 of the shear blade on the side facing backwards in the direction of drilling rotation, which forms an angle of 45 ° with the axis of the drill head 1.

Claims (9)

7812674-5 Patent claims 1. L. Rock drill, especially for electric or pneumatic hammer drills, with a drill shaft and at least two cutting blades projecting radially from the drill bit tip and a drill bit tip projecting over the outer cutting blades and possibly with a transport screw, characterized by the combination of the following features: a) the drill head (1) comprises a centrally arranged, separated by an annular recess (2) from the outer cutting edges (3) and in the drilling direction over these projecting drill bit tips (8) which are equipped with at least a cemented carbide pin (6, 7, 7 ') arranged centrally relative to the axis of rotation of the drill; b) the outer cutting edges (3) are provided with obliquely relative rotational axis-directed cemented carbide pins (4, 4 ') of the drill head; c) the annular depression (2) is designed as a cutting surface and provided with cemented carbide pins (5, 5 '); d) the outer cutting edge edges (3) project in the drilling direction over the cutting surface (2) between the tip of the drill head and the outer wing edges; e) the cutting vanes have recesses (ll) on their side facing backwards in the direction of drilling rotation. Rock drill according to claim 1, characterized by several cemented carbide pins (5, 5 ') on the inner cutting surface (2), which have different distances from the center. Rock drill according to Claim 1, characterized in that the cemented carbide pins (4, 4 ') on the outer cutting edge edges form an angle of 300 with the drill shaft. Rock drill according to Claim 1, 2 or 3, characterized in that the drill bit tip (8), in addition to a central cemented carbide pin (6), has at least two more carbide pins arranged obliquely relative to the drill shaft and lying at the same distance from the central pin (6). (7, 7 ') 7812674-5 Rock drill according to Claim 4 and 4, characterized in that the cemented carbide pins (7, 7 ') on the tip (8) of the drill head are arranged at an angle of 300 relative to the drill shaft. Rock drill according to Claim 1, characterized in that the cutting surface (9) of the drill bit tip (8) and the cutting surfaces (10) of the cutting edge (3) form an angle of 600 with the drill shaft. Rock drill according to Claim 1, characterized in that the cutting surfaces (9) of the drill bit tip (8) and the cutting surfaces (10) of the cutting edge (3) lie on a conical mantle surface. Rock drill according to Claim 1, characterized in that the plane (III, III ') characterized by the cemented carbide tip (6, 7, 7') characterized by the drill bit tip (8) simultaneously halves the angle between two shear edges (3). Rock drill according to claim 1, characterized in that the bevel (11) of the shear edge (3) forms an angle of 450 or less with the drill shaft.