METHOD FOR MANUFACTURING A THIN-WALLED PART

Abstract

A method for manufacturing a thin-walled part having curved surfaces, in particular a turbine blade by a machine tool comprising roughing process and semi-finishing process. At least one of the roughing process and the semi-finishing process is accomplished by flank milling.

Claims

1. A method for manufacturing a thin-walled part having curved surfaces by a machine tool comprising a roughing process and semi-finishing process, wherein at least one of the roughing process and the semi-finishing process is accomplished by flank milling.

2. The method according to claim 1, wherein cutting tools used for the flank milling is first characterized to obtain characteristic data of the cutting tool and an operation mode is selected based on the obtained characteristic data.

3. The method according to claim 2, wherein the selected operation mode is a process damping mode, in which the turbine blade is machined at a low spindle speed and high depth of cut.

4. The method according to claim 2, wherein the selected operation mode is a stable mode in which the spindle speed is higher than the process damping mode and the depth of cut is smaller than the process damping mode.

5. The method according to claim 2, wherein based on the characteristic data of the cutting tool the operation mode is selected to enable a full-slot milling of at least a part of the turbine blade.

6. The method according to claim 2, wherein the characterizing the tool is conducted by a tap testing.

7. The method according to claim 2, the characteristic data includes one or more of: spindel speed, depth of cut, stability state and chatter frequency.

8. The method according to claim 1, further comprising obtaining characteristic data of the workpiece.

9. The method according to claim 2, further comprising inputting the characteristic data of the cutting tools and/or the characteristic data of the workpiece into a simulation tool to determine the machining parameters applied to machine the turbine blade.

10. The method according to claim 3, wherein the turbine blade has a platform and the process damping mode is selected to accomplish the roughing of the platform.

11. A machine tool for manufacturing a thin-walled part having curved surfaces, in particular a turbine blade including an airfoil and a platform, comprising roughing process and semi-finishing process by tools used in a machine tool, wherein the method of claims according to claim 1 is applied.

12. A machine tool according to claim 11, comprising a controller configured to control the machine, wherein the determined machine parameters according to claim 9 is supplied to the controller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to describe the manner in which advantages and features of the disclosure can be obtained, in the following a more particular description of the principles briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only exemplary embodiments of the disclosure and are not therefore to be considered to be limiting of its scope. The principles of the disclosure are described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0029] FIG. 1 illustrates a simplified schematic of a single turbine blade

[0030] FIG. 2 illustrates the milling method according to present invention;

[0031] FIG. 3 shows the results of conducted tap testing for two cutting tools;

[0032] FIG. 4 illustrates results of tap testing;

[0033] FIG. 5 illustrates the 5-axis flanking milling; and

[0034] FIG. 6 illustrates an embodiment to mill the single blade.

EXEMPLARY EMBODIMENTS

[0035] FIG. 1 illustrates a schematic of a single machined turbine blade 10 including an airfoil 1, a platform 2, and a blade root 3, which can be manufactured by the method of the present invention. However, the method of present invention is not limited to machine turbine blade and not limited to this particular shape of the turbine blade. For example, the turbine blade having additionally a shraud can also be machined by this method.

[0036] FIG. 2 shows the main steps included in the method of the present invention: characterizing a cutting tool 21, selecting an operation mode 22, determining machining parameter 23 and machining workpiece 24. Before milling the workpiece by a machine tool, at least one cutting tool used for the milling is characterized for example by a tap testing to identify the critical frequency range regarding the vibration to obtain stability lobes.

[0037] FIG. 3 shows the results of the conducted tap testing for two cutting tools T1 and T2 depicted in stability lobes. Three operation regions can be derived from the obtained result: unstable region, stable region, process damping region. In the unstable region, the self-excited vibration occurs strongly such that this region should be avoided for the machining. The stable region is normally the desired machining region, since the machining can be accomplished in a stable state and high spindle speed can be selected. For example, the spindle speed of 4000 rev/min can be applied to mill a depth of cut of 2 mm. In the process damping region, the applicable spindle speed is low but a large of depth of cut can be applied. As shown in the FIG. 4 the process damping occur at the spindle speed of 420 rpm and 210 rpm for tools T1 and T2, respectively. The applicable depth of cut are higher than 300 mm. Selecting this operation mode enables a full-slot milling, which reduces the machining time.

[0038] The identified spindle speed can be further supplied into a simulation tool to predict for example the relation between the cutting force and the resulting deflection of the workpiece. In this manner, the machining parameters used for the set-up the milling process can be selected properly. In this embodiment, if the operation is not conducted in the process damping range, the full-slot flank milling cannot be used, because the tool will be broken at such high rotation speed. Even relative lower rotation speed is selected, the total machining time required to machine the part is reduced, since the material removal rate is increased dramatically, thereby the productivity is improved. When the maximum tangential cutting force resulting a tolerable deflection can be applied to machine the workpiece, the machining time can be saved without reduction of the quality of the manufactured single blade.

[0039] FIG. 5 shows the full-slot milling a platform using the process damping mode. FIG. 6 shows the case if the stable operation mode is selected. The platform has to be milled in a spiral milling path having a slope of e.g. 2 mm.