Reamer

Abstract

A reamer has a basic tool body made of hard metal (12) and a plate-like cutting insert (18) inserted into a recess (28) at the front. The cutting insert (18) is at least partially made of polycrystalline diamond, its cutting edges (20) situated axially offset relative to the cutting edges (30) on the basic tool body (12), thus engaging with the workpiece later.

Claims

1. A reamer defining a longitudinal axis and comprising: a basic tool body at least partially made of hard metal, the basic tool body having a clamping end and a front end opposite the clamping end that penetrates into the workpiece, the front end having a front side and hard metal cutting edges that protrude axially around a circumference of the front end, the front side having an axial recess into which a cutting insert at least partially made of polycrystalline diamond is inserted; wherein the cutting insert hag has two opposing flat surfaces and a plurality of radially protruding diamond cutting edges; wherein the hard metal cutting edges are arranged such that, in a cutting feed direction, cutting first starting from hard metal cutting edges at the front end, followed by the diamond cutting edges; and wherein the hard metal cutting edges have a smaller cutting diameter than the diamond cutting edges.

2. The reamer according to claim 1, wherein the hard metal cutting edges and the diamond cutting edges alternate circumferentially.

3. The reamer according to claim 1, wherein the recess has a base surface that is perpendicular to the longitudinal axis of the reamer.

4. The reamer according to claim 1, wherein the front end of the basic tool body has a plurality of axially protruding fingers on which the hard metal cutting edges are formed.

5. The reamer according to claim 1, wherein the cutting insert has a polygonal design with radially outer points on which the diamond cutting edges are formed.

6. The reamer according to claim 1, wherein the cutting insert is brazed to the basic tool body.

7. The reamer according to claim 1, wherein the cutting insert is a composite component having a front layer of polycrystalline diamond and an adjacent hard metal carrier layer.

8. The reamer according to claim 1, wherein the cutting insert has at least two diamond cutting edges.

9. The reamer according to claim 1, wherein the difference in diameter between the diameters on which the hard metal cutting edges and the diamond cutting edges are situated is less than 1/10 mm.

10. The reamer according to claim 1, wherein the cutting insert is arranged with the flat surfaces being perpendicular to the longitudinal axis of the reamer.

11. The reamer according to claim 3, wherein the cutting insert is arranged with the flat surfaces being perpendicular to the longitudinal axis of the reamer.

12. The reamer according to claim 8, wherein the diamond cutting edges are evenly distributed around a circumference of the cutting insert.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an exploded view of the reamer according to the invention, and

(2) FIG. 2 shows the reamer according to FIG. 1 in a completely manufactured state.

DETAILED DESCRIPTION

(3) Both FIG. 1 and FIG. 2 show a reamer 10 that has a basic tool body 12 made of hard metal. The basic tool body 12 has a clamping end 14 with which it can be inserted into a receptacle of a tool machine and rotated thereby.

(4) There is a so-called front end 16 opposite of the clamping end. A plate-like cutting insert 18 is attached at the front side of this front end 16. The cutting insert 18 has a plurality of cutting edges 20 made of polycrystalline diamond distributed around the circumference.

(5) The cutting insert itself is a composite component with an upper layer or plate 22 made of the polycrystalline diamond and an underlying carrier plate 24 made of hard metal. The two plates 22, 24 are sintered together and form a unit.

(6) The holder 12 in turn has a recess 28 on its face 26 at the front end 16 that is flat and aligned at a right angle to the longitudinal axis of the reamer.

(7) A plurality of fingers resembling the points of a crown protrude across from this recess 28, each of the fingers forming the end of the entire reamer that axially projects the farthest forward. Hard metal cutting edges 30 are formed on the outer circumference of these, in this case three points or fingers, which are an integral part of the basic tool body and therefore made of hard metal. These hard metal cutting edges are on a diameter relative to the center axis and rotational axis of the reamer that is minimally smaller than the diameter on which the diamond cutting edges 20 are situated.

(8) At the front end 16 with the carrier plate 24 pointing forward, the cutting insert 18 is placed ahead on the base surface of the recess 28, which is also indicated by the arrow of reference number 28 in FIG. 1, and firmly connected to the basic tool body made of hard metal.

(9) The center-facing, i.e. radially inward facing, surfaces 34 of the axially protruding crown-like or finger-like projections that form the hard metal cutting edges 30 are rough alignment surfaces for the insertion of the cutting insert 18.

(10) In the completed design of the reamer shown in FIG. 2, the hard metal cutting edges 30 are in front of the diamond cutting edges 20 in the axial feed direction X such that they come into contact with the workpiece first and cut it to a larger diameter. Only afterwards do the cutting edges 20 engage with the workpiece. However, because the cutting edges 20 are situated on a diameter that is minimally larger, and preferably only less than 1/10 mm larger, than the diameter arranged coaxially herewith, on which the hard metal cutting edges 30 are situated, the cutting capacity that must be provided by the diamond cutting edges is very low, as a result of which the heat produced on the diamond cutting edges 20 is also very low.

(11) The basic tool body can, of course, be composed of several parts, for example a hard metal part near the front end 16 and a tougher, cheaper metal in the region of the clamping end 14.

(12) As is evident from FIGS. 1 and 2, the basic tool body 12 has a front end with a crown-like design, the cutting edges, along with the protruding fingers on which they are formed, forming the points of the crown.

(13) The cutting insert 18 in turn has a star-shaped, but plate-like design. The diamond cutting edges 20 form the points.

(14) To perfectly center the cutting edges 20 relative to the cutting edges 30, the cutting edges 20 are finish-ground only after the cutting edge 18 has been brazed on such that it is also centered relative to the center axis of the basic tool body 12.