Tool holder for tangential cutting insert

Abstract

In the case of a tool holder having a receptacle for a cutting insert, in particular a tangential cutting insert having eight lips, having a lateral bearing surface, a rear bearing surface and a bottom surface, the bottom surface is quadrangular in plan view and has a raised supporting region which has two supporting surfaces, positioned obliquely with respect to one another, for the cutting insert.

Claims

1. A tool holder having a receptacle for a cutting insert having eight lips, the tool holder comprising: a lateral bearing surface, a rear bearing surface, and a bottom surface, wherein the bottom surface is quadrangular in plan view and has a raised supporting region which has two supporting surfaces positioned obliquely with respect to one another, for the cutting insert; wherein the rear bearing surface has a raised, generally planar first surface and a plurality of generally planar second surfaces extending directly from the first surface, each of the second surfaces being disposed obliquely with respect to the first surface to form a truncated pyramidal shape; and wherein a geometry of the rear bearing surface differs from a geometry of the bottom surface.

2. The tool holder as claimed in claim 1, wherein a perimeter of the supporting region is offset from the perimeter of the bottom surface, defining a shoulder between the perimeter of the bottom surface and the perimeter of the supporting region.

3. The tool holder as claimed in claim 1, wherein the supporting region has a raised ridge which separates the two supporting surfaces from one another.

4. The tool holder as claimed in claim 3, wherein the ridge extends diagonally over the supporting region.

5. The tool holder as claimed in claim 1, wherein the bottom surface is part of a shim which is fitted to the tool holder.

6. The tool holder as claimed in claim 5, wherein the shim is screwed to the tool holder.

7. The tool holder as claimed in claim 5, wherein the shim is made of carbide.

8. The tool holder as claimed in claim 5, wherein an underside of the shim has been ground.

9. The tool holder as claimed in claim 1, wherein the bottom surface is configured in one piece with the tool holder.

10. The tool holder as claimed in claim 9, wherein the bottom surface has been hardened.

11. The tool holder as claimed in claim 10, wherein the bottom surface has been laser hardened, induction hardened or nitride.

12. An assembly having a tool holder as claimed in claim 1, further comprising a tangential cutting insert which is fitted in the receptacle and rests on the bottom surface, wherein the bottom surface protrudes outwardly beyond the cutting insert when viewed with respect to a plane which is defined by an exposed base surface of the cutting insert.

13. The assembly as claimed in claim 12, wherein the length and the width of the bottom surface are greater than the length and the width of the cutting insert supported thereon.

14. The assembly as claimed in claim 12, wherein the cutting insert has a plurality of cutting edges, with the cutting edges that face the bottom surface being arranged at a distance from the bottom surface.

15. The assembly of claim 12, wherein a perimeter of the supporting region is offset from the perimeter of the bottom surface, defining a shoulder between the perimeter of the bottom surface and the perimeter of the supporting region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described in the following text with reference to two embodiments which are illustrated in the drawings, in which:

(2) FIG. 1 shows a perspective view of a tool holder according to a first embodiment of the invention;

(3) FIG. 2 shows a side view of the tool holder from FIG. 1;

(4) FIG. 3 shows a front view of the tool holder from FIG. 1;

(5) FIG. 4 shows a plan view of the tool holder from FIG. 1;

(6) FIG. 5 shows a plan view of a shim which is used in the tool holder from FIG. 1;

(7) FIG. 6 shows a side view of the shim from FIG. 5;

(8) FIG. 7 shows a front view of the shim from FIG. 5;

(9) FIG. 8 shows a section along the plane VIII-VIII in FIG. 5;

(10) FIG. 9 shows a section along the plane IX-IX in FIG. 5;

(11) FIG. 10 shows a perspective view of the tool holder from FIG. 1 with a cutting insert fitted therein;

(12) FIG. 11 shows a side view of the tool holder with a cutting insert from FIG. 10;

(13) FIG. 12 shows a front view of the tool holder with a cutting insert from FIG. 10;

(14) FIG. 13 shows the detail XIII from FIG. 12 on an enlarged scale;

(15) FIG. 14 shows a plan view of the tool holder with a cutting insert from FIG. 10;

(16) FIG. 15 shows a perspective view of a tool holder according to a second embodiment of the invention;

(17) FIG. 16 shows a side view of the tool holder from FIG. 15; and

(18) FIG. 17 shows a front view of the tool holder from FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

(19) FIGS. 1 to 14 show a tool holder 5 according to a first embodiment. It contains a holding portion 6 which is fitted on a shank 7 which is shown broken away here. The shank 7 can be mounted on a tool holder carrier.

(20) The holding portion 6 of the tool holder 5 is provided with a receptacle 8 in which a cutting insert 9 (see FIGS. 10 to 14) can be fitted.

(21) The receptacle 8 contains a lateral bearing surface 10, a rear bearing surface 12 and a bottom surface 14. The surfaces 10, 12, 14 serve to support the cutting insert 9.

(22) The cutting insert 9 is a tangential cutting insert as is known in principle from DE 10 2007 022 536 A1. It has two base surfaces 20 which have a generally square shape and are rotated with respect to one another. Provided between the peripheries of the base surfaces 20 are four side surfaces 22, with each side surface forming two main lips 24 with the base surfaces. A secondary lip 26 is formed in each case at the transition between adjacent side surfaces 22. Each main lip 24 merges into the adjacent secondary lip 26 via a corner radius 28. Overall, the cutting insert 9 has eight lips which are each formed by a main lip 24 and a secondary lip 26 together with the corner radius 28.

(23) In the first embodiment, the bottom surface 14 (the lower surface in FIG. 1) of the receptacle 8 is a shim 30 which is configured separately from the tool holder 5 and is fitted on the latter. In plan view, the shim 30 has a quadrangular and in this case generally parallelogram-like shape (see FIG. 5) and has a raised supporting region 32 which is surrounded by an encircling shoulder 34 which is located at a lower level than the supporting region 32.

(24) The supporting region 32 is formed by two supporting surfaces 36, positioned obliquely with respect to one another, which have a generally triangular shape, and a raised ridge 38 arranged between the two supporting surfaces 36. Said ridge extends diagonally over the bottom surface 14, specifically along the longer diagonal (see FIG. 5). The two supporting surfaces 36 are in this case inclined at an angle of 10 with respect to a plane which is defined by the ridge 38 or the underside of the shim 30. As can be seen in particular in FIG. 8, in each case a part of the bottom surface 14 drops toward the longer side peripheries on account of the inclination of the two supporting surfaces 36 toward the outside, i.e. away from the ridge 38.

(25) The shim 30 can consist of carbide or some other suitable material with a high degree of hardness. In this way, the desired wear resistance in particular of the bottom surface 14 is achieved. Preferably, the underside 40 of the shim 30 has been ground in order to obtain a particular planar bearing surface by way of which the shim 30 is supported in the tool holder 5. In order to fasten the shim 30, use can be made of a fastening screw (not shown here) which extends through a centrally arranged opening 42.

(26) When the tangential cutting insert 9 is arranged in the receptacle 8, it is supported by way of one of its side surfaces on the bottom surface 14 of the shim 30, in particular on the two supporting surfaces 36. The latter are configured such that the cutting edges 24, 26, which are located directly opposite the shim 30, are located at a short distance from the shoulder 34 of the shim 30 (see in particular FIGS. 11 to 13 with the distance a indicated there).

(27) With regard to its dimensions, the shim 30 is also configured such that it protrudes laterally beyond the cutting insert 9, in particular beyond a plane which is defined by the laterally arranged base surface 20 (see in particular FIG. 10) and also beyond the secondary lip 26 arranged on the front side of the tool holder. In FIG. 13, the lateral protrusion of the shim 30 beyond the plane defined by the corresponding base surface 20 (and thus also by the main lip 24 arranged there) is designated s. The shim 30 also protrudes forwardly, i.e. toward the observer with respect to FIG. 13, in the region of the secondary lip 26 shown in FIG. 13. As a result of the protrusion of the shim 30, the lips located opposite the shim 30 are protected well against damage by chips. In this case, the protrusion of the shim 30 is not disruptive during operation, since the inactive lips protected by the shim 30 are set back with respect to the active lips of the cutting insert; this is produced by the fitting, inclined in two directions, of the cutting insert 9 on the tool holder 5 (see FIGS. 11 and 12).

(28) FIGS. 15 to 17 show a tool holder according to a second embodiment. The same reference signs are used for the elements known from the first embodiment, and reference is made in this respect to the statements made above.

(29) The difference between the first and second embodiments consists in that in the second embodiment the base surface 14 is configured as an integral constituent part of the tool holder 5, i.e. directly as one of the boundary surfaces of the receptacle 8. The geometry is the same as in the first embodiment; the base surface 14 thus has a raised supporting region with an encircling shoulder 34, two supporting surfaces 36 and the ridge 38.

(30) In order to ensure the desired hardness of the base surface 14, the material of the tool holder 5 in the region of the base surface 14 is hardened, for example laser hardened, induction hardened or nitrided.