Drilling tool for chip removing machining as well as a loose top and a basic body therefor

A drilling tool for chip removing machining, comprising:

• a basic body, including:
• front and rear ends, and an envelope surface that includes two countersunk chip flutes and is concentric with a first center axis around which the basic body is rotatable in a given direction of rotation;
• and
• a loose top, including:
• front and rear ends, a pair of envelope part surfaces concentric with a second center axis, and two chip flutes countersunk in relation to the pair of envelope part surfaces between which two bars project radially from a central core, the front end including a cutting edge and at least one clearance surface positioned rotationally behind the cutting edge, the rear end forming an axial contact surface;
• two opposite side contact surfaces;
• a pair of convex guide surfaces situated axially behind the side contact surfaces, the guide surfaces being concentric with the second center axis and radially spaced-apart from the second center axis at a distance that is less than the radial distance between the second center axis and a respective side contact surface;
• and
• a pair of torque-carrying tangential contact surfaces that are situated radially inside the envelope part surfaces and outside the side contact surfaces,
• wherein the front end of the basic body includes a jaw that is delimited by a bottom axial support surface against which the axial contact surface of the loose top is pressed, and two peripherally situated branches that protrude axially from the bottom axial support surface, the branches being elastically bendable to clamp the loose top in an operative end position in the jaw by a pair of inner support surfaces of the branches being resiliently pressed against the side contact surfaces of the loose top, and a pair of rotationally heading tangential support surfaces of the branches being pressed against the tangential contact surfaces of the loose top, besides which axially behind the inner support surfaces concave guide surfaces are arranged for co-operation with the two convex guide surfaces of the loose top, and the loose top being axially inserted into the jaw of the basic body and turnable to and from an operative end position, in which the tangential support surfaces of the branches are pressed against the tangential contact surfaces of the loose top, and
• wherein
• the axial contact surface of the loose top extends perpendicular to the second center axis of the loose top between borderlines adjacent to the two envelope part surfaces,
• a greatest diameter between the pair of concave guide surfaces of the branches is greater than an analogous diameter between the pair of convex guide surfaces of the loose top such that the guide surfaces provisionally hold the loose top in an intermediate position during the turning-in toward the operative end position, and
• the pair of concave guide surfaces of the branches lack contact with the pair of convex guide surfaces of the loose top in the operative end position.