Patent Application
20160349729
The present invention relates to the process of machining a component. It refers to a method for machining a component on a multi-axis machine tool driven by an NC-controller.
It further refers to an apparatus for conducting such method.
The machining of e.g. turbine blades (e.g. during reconditioning, but also for preparation of subsequent manufacturing steps) is today done with either information on nominal geometry (->standard machining) or information on nominal and actual geometry (->adaptive machining).
For parts or components that are produced from graded material or from different material layers (e.g. base material plus one or more coating layers), the detection of the surface material (material composition/chemical elements) is today often done visually, sometimes also in an analysis step requiring specific equipment with either destructive or non-destructive methods.
The information on the actual layer material composition however can be essential to control material removal (e.g. by milling, grinding, EDM, laser ablation, or the like) and/or material addition (e.g. by laser cladding, selective laser melting, or the like).
State of the art adaptive machining processes make use of geometrical information (nominal and measured) to create a tool path for the machining tool. This is done with commercially available software packages (e.g. from DELCAM).
Adaptive machining is described in various documents.
For example, document U.S. Pat. No. 8,578,579 B2 discloses a method of repair including removing a deformed portion of a component to define a native component portion and adding a replacement portion to the native component portion. The replacement portion is adaptively machined based on one or more parameters of the native component portion and based on one or more original design parameters of the component.
Document U.S. Pat. No. 8,442,665 B2 discloses a system including a three-dimensional object having a non-conforming region, and a photogrammetry device adapted to scan the three-dimensional object. The system further includes optical reference targets and a controller structured to perform functions of repairing the three-dimensional object. The controller commands the photogrammetry device to scan the three-dimensional object, and calculates a nominal surface location and contour for the three-dimensional object. The controller further commands the photogrammetry device to scan the non-conforming region of the three-dimensional object, and calculates a material removal tool path comprising a path adapted to remove material from the object located beyond the nominal surface location and contour. The controller generates a solid model of the damaged region of the object based on the nominal surface location and contour, and computes a material addition tool path according to the solid model.
Document US 2011276166 A1 discloses a method and system for modifying a substrate, such a thin film, solar panel or the like detects error and/or variance and, if needed, re-optimizes the product design and/or process parameters on the fly, so that product can meet the product specification. This allows for methods and systems of process control that can adaptively change the product design in real time.
Document US 2013158698 A1 relates to a fabrication processing system of CIGS thin film solar cell, more particularly to a fabrication processing system CIGS of thin film solar cell equipped with real-time analysis facilities for profiling the elemental components of CIGS thin film using laser-induced breakdown spectroscopy. The system is to provide a process control system for determining whether abnormalities are present or not by measuring physical and chemical properties on continuous production process lines of CIGS thin film solar cell in real time, and performing a production and quality management at the same time by providing a feedback to CIGS fabrication process.
However, it would be highly advantageous to include information about the (varying) local material compositions of a component to be machined in the machining process in order to optimize removal and/or deposit of material in certain surface areas of said component.
One means of detecting material composition is spectroscopy.
However, such spectrometers are today not provided for use inside a machine tool.
In general, the information on chemical composition (measured with a spectrometer) is today not used for adaptive manufacturing processes.
It is an object of the present invention to integrate a spectroscopy device into the machining process on a multi-axis machine tool driven by an NC-controller.
It is another object of the present invention to provide a material data capture and analysis process and its feed-back into an adaptive tool path generation.
These and other objects are obtained by a method according to claim 1 and an apparatus according to claim 12.
According to the invention a method for machining a component on a multi-axis machine tool driven by an NC-controller comprises the steps of:
An embodiment of the inventive method is characterized in that a raster with a plurality of defined or arbitrary raster points is provided for said surface of said component to be machined, and that said material composition of said component is mapped at said raster points of said raster.
Another embodiment of the inventive method is characterized in that said step of removing material from said component comprises one of grinding, milling, Electrical Discharge Machining (EDM), or other material-removing process.
A further embodiment of the inventive method is characterized in that said step of adding material to said component comprises Laser Metal Forming (LMF), or other material-additive process.
Especially, said raster with said plurality of raster points is defined on the basis of a CAD model of said component.
Alternatively, said raster with said plurality of raster points is based on a scan of the geometry of said component.
Just another embodiment of the inventive method is characterized in that steps (c) to (f) are rerun at least one time with the same or a different tool.
A further embodiment of the inventive method is characterized in that said component is a part of a gas turbine.
Especially, said component is a turbine blade.
Another embodiment of the inventive method is characterized in that said said spectroscopy tool is mounted in a fixed position inside said machine tool.
Alternatively, said machine tool is equipped with a tool changer, and that said spectroscopy tool is provided in said tool changer of said machine tool.
The apparatus according to the invention for conducting the inventive method comprises a multi-axis machine tool driven by an NC-controller with tools for removing material from or adding material to a component inserted into and fixed in said machine tool. It is characterized in that a spectroscopy tool is provided at said machine tool for mapping the material composition on a surface of said inserted and fixed component.
An embodiment of the apparatus according to the invention is characterized in that said spectroscopy tool is mounted in a fixed position inside said machine tool.
Alternatively, said machine tool is equipped with a tool changer, and said spectroscopy tool is provided in said tool changer of said machine tool.
The present invention is now to be explained more closely by means of different embodiments and with reference to the attached drawings.
The present invention uses material identification inside a machine tool in an adaptive manufacturing process.
As shown in
With such a configuration a machining process can be realized in accordance with
First of all, the part or component 19 to be machined (e.g. a turbine blade 10 as shown in
In a next step, a spectroscopy tool 27 is used for spectroscopic inspection of the surface of the component 19. The spectroscopy tool is either fixedly mounted on said machine tool 20 or is fetched like a conventional tool from tool changer 29 by tool holder 26. Spectroscopy tool 27 may communicate with the machine control of machine tool 20 either wireless or by wire to transfer the collected material composition data to the central computer system.
Then, the material composition of a surface of component 19 is mapped by means of said spectroscopy tool 27 at certain raster points (32 in
The result of the mapping process is shown in
In a next step, material is removed in area 16 by a first material-removing process or step like grinding or milling or Electrical Discharge Machining (EDM), whereby a tool-specific path for the material-removing tool used has been calculated on basis of the identified area 16.
In a next step, the material in area 17 may be completely removed by one or more additional material-removing steps with the same or different tools.
When material removal is finished (
In summary, the present invention uses material detection inside a machine tool and an adaptive tool path generation, resulting in a material-based closed loop manufacturing process. This process allows a precise and fast reworking of a component (material removal and addition), which is
| Number | Date | Country | Kind |
|---|---|---|---|
| 15169448.6 | May 2015 | EP | regional |
