Fixing arrangement

Abstract

A fixing arrangement for holding a cutting tooth on a cutter. The cutting tooth has a tool head and a shank. The shank is accommodated in a shank-receiving element of the cutter or a holder connected to the cutter. One or several bearing surfaces of the cutting tooth each lies on support surfaces of the cutter. The cutting tooth can be supported in a stable and reliable manner by inclining the support surfaces and the bearing surfaces in a peripheral direction and by providing the cutter with a shoulder which is arranged in the direction of the cutter in an offset position relative to the bearing surfaces, the shoulder being associated with the cutting tooth at a distance.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to a securing arrangement for retaining a cutting tooth on a drill bit, wherein the cutting tooth has a tool head and a shaft, the shaft is accommodated in a shaft receiver of the drill bit or of a holder which is connected to the drill bit, and the cutting tooth rests on support faces of the drill bit with one or a plurality of contact faces. [0003] 2. Discussion of Related Art [0004] A securing arrangement is known from European Patent Reference EP 0 439 821 A 1. In this case, the drill bit includes pocket-shaped notches, into which each base part is welded. The base part has a shaft receiver, which is tapered. The shaft of the cutting tooth can be inserted into the shaft receiver. To create a cone connection, the shaft has a conical outer outline. A spring cotter is used to secure the cone connection and connects the base part to the shaft. [0005] In operation, particularly where the loads ...

AI Technical Summary

Benefits of technology

[0007] This object is achieved with support faces and contact faces that are set to be inclined in a circumferential direction. The drill bit includes a shoulder which is offset relative to the contact faces in the direction of the axis of the drill bit and is associated with and spaced from the cutting tooth. The cutting forces occurring during the cutting operation can be absorbed mostly via the inclined support faces. This type of supporting, in interaction with the space, makes it possible for the shaft of the cutting tooth to be substantially free of the cutting forces and reduces the danger of the tool breaking. Also, the space also makes it possible for the cutting tooth to be adjusted if the support face of the drill bit and / or the contact face of the cutting tooth becoming worn.

[0010] In one embodiment of this invention, the shaft of the cutting tooth is tapered at least over a portion of its longitudinal extension in the direction of its free end. The shaft receiver is also tapered at least in a regional manner, and an outside cross-section of the shaft is smaller than the inside cross-section of the shaft receiver. This arrangement simplifies the mounting of the cutting tooth into the shaft receiver. If the tool head of the cutting tooth includes one or a plurality of radial recesses in its region directed radially inwards, then material pockets are formed on the cutting tooth. Residue material collects in the pockets and forms a layer for protection against wear.

[0012] To improve the cutting performance even further, at a region remote from the shaft, the tool head of the cutting tooth includes a top face, into which a hard material insert, such as a hard metal insert, is inserted.

Problems solved by technology

In operation, particularly where the loads are jerky and intermittent, the cone connection can become worn.

The cutting tooth is then no longer retained without play and this leads to a heavy increase in wear until the tool finally breaks.

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