Rotationally driven multi-bevel step tool

Abstract

The invention relates to a rotationally driven multi-bevel step tool, particularly a step drill for drilling into solid material, comprising a plurality of one-edged or multi-edged cutting steps which are arranged in a staggered manner in the cutting and advancing directions and each have a number of flutes that corresponds to the number of edges. Flutes ( 23, 33 ) adjoining each other in the circumferential direction are separated from each other by a web ( 24 ). According to the invention, the flues ( 23, 33 ) adjoining each other in the circumferential direction of two consecutive cutting steps ( 20, 30 ) in the cutting and advancing directions are connected to each other by a metal-cutting window ( 25 ) that is open on the circumferential side and interrupts the interposed web ( 24 ).

1 . A rotationally driven multi-bevel step tool, particularly a step drill for drilling into solid material, with a plurality of in each case single- or multi-edged cutting steps arranged in a staggered manner in the cutting and feed direction with a number of flutes corresponding to the number of cutting edges in each case, wherein flutes which are adjacent in the circumferential direction are delimited from one another in each case by means of a web, characterised in that
 the flutes, which are adjacent in the circumferential direction, of two successive cutting steps are connected to one another by means of a swarf window which penetrates the web located therebetween and is open on the circumferential side.   
     
     
         2 . The multi-bevel step tool according to  claim 1 , characterised in that the swarf window extends in the radial direction essentially as far as the base of the flute of the trailing cutting step. 
     
     
         3 . The multi-bevel step tool according to  claim 1 , characterised in that the swarf window extends in the axial direction towards the tool shank at least as far as the start of the trailing cutting step. 
     
     
         4 . The multi-bevel step tool according to  claim 3 , characterised in that the swarf window extends in the axial direction towards the tool shank to such an extent that a closest front cutting edge of the trailing cutting step is located essentially centrally in the swarf window. 
     
     
         5 . The multi-bevel step tool according to  claim 3 , characterised in that the swarf window has a predetermined axial length which is determined as a function of the swarf size of the swarf produced in the leading cutting step. 
     
     
         6 . The multi-bevel step tool according to  claim 1 , characterised in that the swarf window is divided in the axial direction in the direction towards the tool shank into a swarf window inlet of increasing radial depth, a swarf window base, which is adjacent to the swarf window inlet and preferably runs axially parallel, and a swarf window outlet of decreasing radial depth, which is adjacent to the swarf window base. 
     
     
         7 . The multi-bevel step tool according to  claim 6 , characterised in that the swarf window base is formed from a planar surface. 
     
     
         8 . The multi-bevel step tool according to  claim 6 , characterised in that the swarf window base is preferably inclined by an predetermined angle with respect to the milling face or a flute face, which extends the milling face, of the flute, which is adjacent in the circumferential direction, of the trailing cutting step. 
     
     
         9 . The multi-bevel step tool according to  claim 6 , characterised in that the swarf window inlet and the swarf window outlet are in each case constructed as concavely curved surfaces. 
     
     
         10 . The multi-bevel step tool according to  claim 1 , characterised in that the swarf window is orientated in the direction of the opening through the web located between the flutes which are adjacent in the circumferential direction at a predetermined angle (α≦90°) relative to the rotational axis of the multi-bevel step tool or relative to the direction of longitudinal extent of the flutes. 
     
     
         11 . The multi-bevel step tool according to  claim 1 , characterised by a preferably integrally constructed support body made from solid carbide and in that the cutting edge(s) of the cutting steps are formed by PCD (polycrystalline diamond) cutting plates arranged on the support body. 
     
     
         12 . The multi-bevel step tool according to  claim 11 , characterised in that the swarf window corresponds with respect to axial length and axial position to the axial length and axial position of a closest cutting plate of the trailing cutting step. 
     
     
         13 . The multi-bevel step tool according to  claim 1 , characterised in that the flutes are constructed linearly. 
     
     
         14 . The multi-bevel step tool according to  claim 1 , characterised by an internally located channel system designed for minimum quantity lubrication for supplying the multi-bevel step tool with coolant/lubricant. 
     
     
         15 . The multi-bevel step tool according to  claim 14 , characterised in that the coolant/lubricant supply of one or a plurality of cutting steps takes place via discharge openings which are in each case located in a front open area behind an assigned front cutting edge. 
     
     
         16 . The multi-bevel step tool according to  claim 1 , characterised in that the cutting steps are constructed in a multi-edged manner in each case with front and circumferential cutting edges equidistantly arranged in the circumferential direction, particularly in a double-edged manner with front and circumferential cutting edges arranged point-symmetrically.