Tool for machining workpieces

#The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2008/008896, filed Oct. 21, 2008, which claims priority of COUNTRY Application No. 10 2007 050 471.5, filed Oct. 23, 2007, incorporated by reference herein. The PCT International Application was published in the German language.

#The invention relates to a tool for machining workpieces.

#The tools referred to here are those which are used for machining workpieces and are preferably designed as drills. They comprise a shank and a cutting insert interchangeably held by said shank. To accommodate the cutting insert, the shank is provided with a slot, into which the cutting insert is inserted. Tools having interchangeable cutting inserts replace conventional tools, in particular twist drills, which are produced throughout from a high-temperature-resistant cutting material, for example carbide or high-speed steel. When this drill becomes worn, the cutting edges are reground as often as possible or are redressed. At the same time, the cutting region is also recoated as a rule. The coating thicknesses and coating inherent stresses increasing in the process prevent frequent redressing of the twist drills. To avoid this disadvantage, tools having a shank and cutting inserts interchangeably held by said shank have been created. It has been found that such modular tools can be produced only with difficulty and at considerable cost. In this case, tools have also been proposed in which the cutting insert is fixed on the shank by additional fastening elements, in particular screws. Exchanging the cutting insert, in particular in restricted space conditions, is very awkward. Modular tools which do not need such fastening elements have also been proposed, but said modular tools do not have sufficient stability and in particular are unable to reliably absorb the forces that occur during the machining of workpieces (WO 84/03241).

#The invention will be explained below with reference to the drawings, in which:

#FIG. 1 shows the front part of the tool with a cutting insert in side view;

#FIG. 2 shows the tool with cutting insert in end view;

#The front part of a tool 1 for machining workpieces is shown in FIG. 1 in side view. Here, this is a tool designed as a twist drill and having a shank 3 which is provided with a slot 7 in the region of its front end 5, said slot 7 accommodating a cutting insert 9. The basic body 11 of the cutting insert 9 comprises a central section 13, which is also designated as a core and which, as explained in more detail below, has conically designed regions which taper in the direction of the front side 15 of the tool 1. Preferably incorporated in the circumferential surface 17 of the shank 3 is a flute 19, which here, facing the viewer in FIG. 1 and relative to the rotation or center axis 21, runs along an imaginary helical line. It is also conceivable for said flute to be formed parallel to the center axis 21.

#The shank 3 of the tool 1 is shown truncated in FIG. 1. At its end opposite the front side 15 of the tool 1, it can be designed in any desired manner and for different types of fastening.

#The tool shown in FIG. 1 is reproduced in end view in FIG. 2. The same parts are provided with the same reference numerals, and so reference is made in this respect to the preceding description.