EP1684932A1

EP1684932A1 - Milling tool and method for milling recesses

Info

Publication number: EP1684932A1
Application number: EP04802639A
Authority: EP
Inventors: Reinhold Meier; Georg Moosrainer; Wilfried SCHÜTTE
Original assignee: MTU Aero Engines GmbH
Current assignee: MTU Aero Engines AG
Priority date: 2003-11-11
Filing date: 2004-10-23
Publication date: 2006-08-02
Also published as: DE10352542A1; US20070172319A1; WO2005046917A1; US7559728B2

Abstract

The invention relates to a milling tool which is used to mill recesses, in particular, circular-shaped grooves, in a workpiece. Said milling tool (10) is disposed on a disk-shaped or plate-shaped base body (14) and on at least one cutting body (15) arranged on the outer periphery of the base body (14). The cutting body or each cutting body (15) is inclined in relation to the disk-shaped base body or the plate-shaped base body (14).

Description

Milling tool and method for milling recesses

The invention relates to a milling tool for milling depressions. The invention further relates to a method for milling recesses.

The present invention relates to the production of groove-like depressions by means of milling. According to the prior art, end mills are used for milling circular, groove-like depressions, the diameter of the end mill corresponding to the width of the groove-like recess to be produced. Should narrow, groove-like depressions, i.e. If grooves are made with a small width, the end mill must have a small diameter. In particular when milling narrow, circular grooves, there is the problem that the end mill is susceptible to wear due to its small diameter, so that the end mill can only be operated with a small feed rate, which ultimately results in only a small removal per unit of time. The milling of narrow, circular grooves using end mills is therefore problematic overall.

Proceeding from this, the present invention is based on the problem of creating a novel milling tool for milling depressions and a novel method for milling depressions.

This problem is solved in that the milling tool mentioned at the outset is further developed by the features of the characterizing part of patent claim 1.

According to the invention, the milling tool has a disk-shaped or plate-shaped base body and at least one cutting body arranged on the outer circumference of the base body, the or each cutting body being angled relative to the disk-shaped or plate-shaped base body. According to an advantageous development of the invention, the or each cutting body is angled in relation to the disk-shaped or plate-shaped base body in such a way that an inner milling radius defined by the or each cutting body is larger than an outer circumferential radius of the disk-shaped or plate-shaped base body. The or each cutting body is angled to one side with respect to a disk-shaped or plate-shaped surface defined by the base body, an outer side of the cutting body with the disk-shaped or plate-shaped surface making an angle of greater than 0 ° and less than 90 °, preferably an angle of Include greater than 5 ° and less than 65 °.

The inventive method for milling depressions is characterized by the features of independent claim 8.

Preferred developments of the invention result from the dependent subclaims and the following description.

An embodiment of the invention is explained in more detail with reference to the drawing, without being limited to this. The drawing shows:

1: a milling tool according to the invention together with a workpiece to be milled in a highly schematic cross section;

2 shows a section of the workpiece to be milled from FIG. 1;

3 shows a side view of a milling tool in the sense of the invention; and

4: a further milling tool according to the invention together with a workpiece to be milled, namely a blade profile to be milled, in a highly schematic, perspective side view.

The present invention is described in greater detail below with reference to FIGS. 1 to 4, with FIGS. 1 and 2 being schematic representations, FIG. 3 showing a preferred exemplary embodiment of a milling tool according to the invention. 4 shows a preferred use of the milling tool.

1 shows the construction principle of a milling tool 10 according to the invention together with a workpiece 11, a circular groove 13 being milled into a surface 12 of the workpiece 11. The groove 13 to be milled has a width DN and a depth TN, wherein FIG. 1 shows, as a further parameter of the circular groove 13 to be produced, an inner radius RZI of the circular groove 13 to be produced. From the inner radius RZI of the groove 13 to be produced and the thickness DN thereof, an outer radius of the circular groove 13 to be produced can be calculated by addition.

The milling tool 10 according to the invention shown in FIG. 1 is used to mill the circular groove 13. The milling tool 10 has a disk-shaped or plate-shaped base body 14 as well as cutting bodies 15 which are angled relative to the base body 14. The cutting bodies 15 have a thickness DS which is adapted to the width DN of the groove 13 to be produced.

The cutting bodies 15 are angled in relation to the plate-shaped or disk-shaped base body 14 such that an inner cutter radius RKI defined by inner edges 16 of the cutting bodies is on the one hand larger than an outer circumferential radius of the disk-shaped or plate-shaped base body 10 and on the other hand larger than the inner radius RZI of Circular groove 13 to be produced. Accordingly, an outer milling cutter radius, not shown in FIG. 1 and defined by outer edges 17 of the cutting bodies, is larger than an outer radius of the groove 13 to be produced.

The cutting bodies 15 are angled toward one side with respect to the base body 14, an outer surface 18 of the cutting bodies 15 and a disk-shaped or plate-shaped surface 19 of the base body 14 defined by the base body 14 having an angle PHI of less than 90 ° and greater than 0 ° includes. The angle PHI is preferably in a range between 5 ° and 65 °, particularly preferably in a range between 5 ° and 35 °. Due to the bending of the cutting body 15 relative to the base body 14 of the milling tool 10 and due to the increased inner radius RKI compared to the inner radius RZI of the groove 13 to be produced, the milling tool 10 is inclined relative to the workpiece 11 to be machined for milling the groove 13. An axis of rotation 20 of the milling tool 10 and the surface 12 of the workpiece 11 to be machined in turn enclose the angle PHI.

2 illustrates a groove 13 produced using the above-described milling tool 10 according to the invention. Due to the angular position of the milling tool 10 relative to the workpiece 11 to be machined, parabolically shaped cutting edges result in the region of the groove 13. Thus, FIG. 2 shows a parabolically shaped one Inner wall 21 and a parabolically shaped outer wall 22 of the circular groove 13 to be produced. Furthermore, FIG. 2 shows a tolerance TOLI between the milled inner wall 21 and the desired shape thereof and a tolerance TOLA between the milled outer wall 22 of the groove 13 and the corresponding desired shape. The sum of TOLI and TOLA results in the total tolerance of the groove 13 to be produced.

By increasing the internal tolerance TOLI, the external tolerance TOLA can be reduced, but it should be noted that due to the geometric conditions, an increase in the internal tolerance TOLI does not reduce the external tolerance TOLA to the same extent or to the same extent. If the internal tolerance is increased, the overall tolerance also increases in any case.

For milling a groove 13 using the milling tool 10 according to the invention, the procedure is such that a workpiece 11 is provided and the inner radius RZI of the groove 13 to be milled and the depth TN and width DN of the groove 13 to be milled are preferably determined for the workpiece 11 , As already mentioned, the width DN of the groove 13 determines the thickness DS of the cutting body 15 of the milling tool 10 according to the invention. In addition to the inner radius RZI, the depth TN and the width DN of the groove 13, the permissible internal tolerance TOLI and the permissible one are made for the same TOLA external tolerance set. The radius RKI and the angle PHI are then determined or calculated from these values. This is preferably done automatically using appropriate software that determines the parameters DS, PHI and RKI by specifying RZI, DN, TN, and TOLI and TOLA. At this point it should be pointed out that for a predefined internal tolerance TOLI the cutting body 15 and the parameters RKI and PHI can be used to calculate the external tolerance TOLA from the thickness DS. Accordingly, it is sufficient to specify only the internal tolerance TOLI as the tolerance value.

It is therefore within the meaning of the present invention not to use an end mill, as is customary in the prior art, for milling narrow, circular grooves, but rather a milling tool that has a plate-shaped or disk-shaped base body and on the outer circumference of the base body arranged cutting body has. The cutting bodies are angled relative to the base body. A cutter radius defined by the cutting bodies, in particular an inside radius of the cutter, is larger than the radius, in particular the inside radius, of the recess to be cut. During milling, the milling tool is inclined relative to the surface into which the groove is to be milled by the angle by which the cutting bodies are angled relative to the plate-shaped base body.

With the aid of the milling tool according to the invention and the method according to the invention for milling circular depressions, a high milling cutter cutting performance can be provided even with narrow grooves, because the milling tool according to the invention is significantly less sensitive to mechanical stresses than end mills. The milling tool according to the invention is characterized by stable operation. Hard metal teeth or ceramic cutting inserts can be used as cutting bodies. The tool costs for the milling tool according to the invention are low.

3 shows a preferred exemplary embodiment of a milling tool, the same reference numbers being used to avoid unnecessary repetitions for the same assemblies. Thus, the milling tool 10 according to FIG. 3 has a plate Shaped or disk-shaped base body 14 and the cutting body 15 angled relative to the base body 14. In the exemplary embodiment in FIG. 3, the angle PHI by which the cutting body 15 is angled to one side relative to the surface 19 is approximately 10 °.

The method according to the invention is particularly suitable for milling narrow, circular grooves. It can be used particularly advantageously in the reworking or repair of grooves on gas turbine components that have deformed during operation, in which a groove to be machined is no longer circular, but oval or polygonized. This can also be carried out with the milling cutter according to the invention by first measuring the groove deformed during operation and, depending on this, influencing the milling tool in the sense of an adaptive milling method for machining the groove. In particular, the angle PHI is adjusted here.

Furthermore, it is within the meaning of the present invention to use the milling tool according to the invention or the method according to the invention for milling operations on integrally bladed rotors, which are also referred to as blisk or bling. The method is particularly suitable for simplified blade profile milling on blisks or blings. With the aid of the method according to the invention, flow channels between adjacent blades can be milled out on blisks or blings quickly and with a high metal removal rate. Such milling on blisks or blings can be done as rough machining and as final machining. For finishing, a 5-axis milling machine is preferably used, with the aid of which the milling tool can be precisely controlled to every point of a profile to be milled.

The milling tool according to the invention and the method according to the invention are also suitable for manufacturing individual blades, which will be described below with reference to FIG. 4. 1 shows a milling tool 10 according to the invention, with which a suction side 23 of an individual blade 24 is milled out according to FIG. 4. The milling tool 10 according to FIG. 4 corresponds in principle to the milling tool 10 according to FIG. 1, so that to avoid repetitions for the same assemblies same reference numbers are used. The milling tool 10 is driven to rotate in the direction of arrow 25. During milling, the milling tool 10 continues to be moved into the material in the direction of the axis of rotation. When milling the suction side 23 of the individual blade 24, the inner edge 16 of the milling tool 10 must accordingly be adapted to the contour of the suction side 23. If a pressure side 26 of the individual blade 24 opposite the suction side 23 is to be milled out, then depending on the difference in curvature between the suction side 23 and the pressure side 26, either the outer edge 17 of the same milling tool 10 can be used, or the milling tool is changed. Here, too, rough machining and also finishing can be carried out on the individual blade 24. 4, the milling tool 10 must be designed such that no collision with blade contours of the blisk or bling takes place in any position thereof.

Claims

claims

1. Milling tool for milling recesses, in particular circular grooves, into a workpiece, with a disk-shaped or plate-shaped base body (14) and with at least one cutting body (15) arranged on the outer circumference of the base body (14), the or each cutting body ( 15) is angled relative to the disk-shaped or plate-shaped base body (14).

2. Milling tool according to claim 1, characterized in that the thickness (DS) of the or each cutting body (15) corresponds approximately to the width (DN) of the recess (13) to be milled.

3. Milling tool according to claim 1 or 2, characterized in that the or each cutting body (15) is angled relative to the disk-shaped or plate-shaped base body (14) such that an inner milling radius (RKI) defined by the or each cutting body (15) is larger is as an outer circumferential radius of the disk-shaped or plate-shaped base body (14).

4. Milling tool according to one or more of claims 1 to 3, characterized in that the or each cutting body (15) relative to the disc-shaped or plate-shaped base body (14) is angled such that the or each cutting body (15) relative to one of the base body (14) defined disc-shaped or plate-shaped surface (19) is angled to one side, an outer side of the cutting body (18) including the surface (19) including an angle (PHI) of greater than 0 ° and less than 90 °.

5. Milling tool according to claim 4, characterized in that the outside (18) of the cutting body (15) with the surface (18) of the base body (14) enclose an angle (PHI) of greater than 5 ° and less than 65 °.

6. Milling tool according to claim 4, characterized in that the outside (18) of the cutting body (15) with the surface (18) an angle (PHI) of greater than 5 ° and less than 35 °, preferably an angle (PHI) of Include 10 °.

7. Milling tool according to one or more of claims 1 to 6, characterized in that a milling radius defined by the or each cutting body (15) is larger than the radius of a circular recess (13) to be milled.

8. A method for milling recesses (13), in particular circular grooves, into a workpiece (1 1), the workpiece being milled from a milling tool (10) in such a way that a desired depression results, characterized in that a milling tool (10) according to one or more of claims 1 to 7 is used.

9. The method according to claim 8, characterized in that during milling an axis of rotation (20) of the milling tool (10) with the surface (12) of the workpiece (1 1) into which the circular recess is milled, an angle (PHI) of greater than 0 ° and less than 90 °.

10. The method according to claim 8 or 9, characterized in that the angle (PHI) between the axis of rotation (20) of the milling tool (10) and the surface (12) of the workpiece (1 1) into which the circular recess is milled, corresponds approximately to the angle (PHI) between the outside (18) of the cutting body (15) and the disk-shaped or plate-shaped surface (19) of the base body (14).

1 1. The method according to one or more of claims 8 to 10, characterized in that in addition to a radius (RZI), the depth (TN) and the width (DN) of the circular recess (13) to be milled, an allowable tolerance (TOLI , TOLA) is defined for the deepening, a suitable milling radius (RKI) and a suitable angle (PHI) between the Outside (18) of the cutting body (15) of the milling tool and the disk-shaped or plate-shaped surface (19) of the base body (14) of the milling tool (10) is calculated.

12. The method according to claim 1 1, characterized in that a tolerance (TOLI) for a circular inner wall and / or a tolerance (TOLA) for a circular outer wall of the circular recess to be milled is determined.

13. Use of a milling tool according to one or more of claims 1 to 7 for milling circular depressions, in particular circular grooves, on rotationally symmetrical, disk-shaped or ring-shaped components, namely on gas turbine components.

14. Use of a milling tool according to one or more of claims 1 to 7 for machining groove-shaped depressions on gas turbine components deformed during operation.

15. Use of a milling tool according to one or more of claims 1 to 7 for milling flow channels between adjacent blades or blade spaces in the manufacture of integrally bladed rotors (blisk or bling) of a gas turbine.

16. Use of a milling tool according to one or more of claims 1 to 7 for milling individual blade profiles for gas turbine blades.