Patent Application
20130116817
1. Technical Field
This disclosure relates generally to machining and inspecting a workpiece and, more particularly, to machining and inspecting a workpiece with independent positioning systems.
2. Background Information
A typical system for machining and inspecting a workpiece (e.g., a component of a gas turbine engine) includes a positioning system and a device mount (e.g., a chuck). During a machining operation, a machining tool (e.g., a milling bit) is secured to the device mount. The positioning system moves the machining tool relative to the workpiece such that the machining tool can machine a feature (e.g., a cut) into the workpiece. The machining tool is removed from the device mount upon completion of the machining operation. During a subsequent inspection operation, a contact probe is secured to the device mount. The positioning system moves the contact probe relative to the workpiece such that the contact probe can map a geometry of the machined feature. The mapped geometry can then be compared to a reference geometry to determine whether the workpiece complies with a workpiece design specification. Such an inspection operation, however, does not account for error in the calibration of the positioning system because both the machining tool and the contact probe are manipulated by the positioning system; i.e., positioning system calibration error that affects the machining operation in turn would also affect the inspection operation. The inspection operation therefore may approve a workpiece that does not satisfy the workpiece design specification.
According to one aspect of the invention, a system is provided for machining and inspecting a workpiece. The system includes a workpiece support, a tool positioning system, a machining tool, a measuring device positioning system, a measuring device, and a processor. The workpiece support is adapted to support the workpiece during the machining and the inspection thereof. The tool positioning system is connected to the machining tool. The tool positioning system is adapted to move the machining tool relative to the workpiece support such that the machining tool machines a workpiece feature into the workpiece as a function of reference geometry data. The measuring device positioning system is connected to the measuring device. The measuring device positioning system is adapted to move the measuring device relative to the workpiece support independent of the tool positioning system. The measuring device is adapted to map a geometry of the workpiece feature and to provide workpiece geometry data indicative thereof. The processor is adapted to process the workpiece geometry data and the reference geometry data to compare the geometry of the workpiece feature to a reference geometry.
According to another aspect of the invention, a method is provided for machining and inspecting a workpiece. The method includes steps of: (a) supporting the workpiece with a workpiece support; (b) moving a machining tool relative to the workpiece with a tool positioning system, and machining a workpiece feature into the workpiece with the machining tool as a function of reference geometry data; (c) moving a measuring device relative to the workpiece with a measuring device positioning system that is independent of the tool positioning system, and mapping a geometry of the workpiece feature with the measuring tool to provide workpiece geometry data indicative thereof; and (d) processing the workpiece geometry data and the reference geometry data with a processor to compare the geometry of the workpiece feature to a reference geometry.
The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings.
The base 14 extends laterally (e.g., substantially parallel a y-axis) between a first side 24 and a second side 26. The base 14 extends longitudinally (e.g., substantially parallel an x-axis) between a third side 28 and a fourth side 30. The base 14 extends vertically (e.g., substantially parallel a z-axis) between a first end 32 and a second end 34.
The workpiece support 16 is adapted to move a workpiece mount 36 relative to one or more axes. In the embodiment illustrated in
The machining system 18 (e.g., a computer numerical control “CNC” machine) includes a machining tool 46 and a tool positioning system 48. The machining tool 46 can be configured as, for example, a drilling, boring, milling or grinding bit for a rotary tool, or a nozzle for a fluid and/or abrasive flow jet machine. The present invention, however, is not limited to any particular type of machining tool configuration.
The tool positioning system 48 is adapted to move the machining tool 46 relative to one or more axes. In the embodiment illustrated in
The inspection system 20 includes a measuring device 60 and a measuring device positioning system 62. In the embodiment illustrated in
Referring again to
Referring again to
The controller 22 may be implemented using hardware, software, or a combination thereof. The hardware may include, for example, one or more processors, a memory, analog and/or digital circuitry, etc. The controller 22 is in signal communication (e.g., hardwired or wirelessly connected) with the workpiece support 16, the machining system 18 and the inspection system 20.
In some embodiments, the system 10 may further include a housing. In the embodiment illustrated in
In step 402, the workpiece 12 is secured to the workpiece mount 36. In some embodiments, the workpiece 12 is secured such that there is a known spatial distance and orientation between the workpiece 12 and the origin 76 where, for example, the origin 76 is located on the workpiece support 16.
In step 404, the controller 22 signals the workpiece support 16 to move to the machining position 72 (not shown) where the workpiece 12 has a certain spatial position and orientation relative to the machining tool 46. In some embodiments, workpiece positional data indicative of the spatial position and orientation of the workpiece is preloaded into the controller 22. In other embodiments, the workpiece positional data is determined during operation. The workpiece positional data can be determined, for example, from (i) the spatial distance and orientation between the workpiece 12 and the origin 76, and (ii) a known (or determinable) spatial distance and orientation between the origin 76 and the machining tool 46.
In step 406, the controller 22 signals the machining system 18 to machine at least one workpiece feature 78 (e.g., see
In step 408, the controller 22 signals the workpiece support 16 to move to the inspection position 74.
In step 410, the controller 22 signals the inspection system 20 to map a geometry of each workpiece feature 78 machined during step 406, and to provide workpiece geometry data indicative thereof. The tetra “map” is used herein to describe a process for determining a measured coordinate for one or more points on a surface of the workpiece feature 78. The term “measured coordinate” is used herein to describe a spatial location of a certain point on a surface of a workpiece feature relative to an origin. The measured coordinates can be determined, for example, by moving the measuring device 60 with the measuring device positioning system 62 such that the measuring device 60 can determine the spatial location of each respective point on the surface of the workpiece feature 78 relative to the origin 76. The measured coordinates are subsequently output from the measuring device 60 as the workpiece geometry data.
In step 412, the controller 22 processes the workpiece geometry data and the reference geometry data to determine geometric deviations between the geometry of each workpiece feature 78 machined in step 406 and a respective one of the reference geometries. The controller 22, for example, can compare each measured coordinate to a corresponding one of the reference coordinates to determine geometric deviation therebetween. Alternatively, the controller 22 can (i) generate a geometric model of the workpiece feature 78 utilizing the measured coordinates, and (ii) compare the generated model to a reference model, included in or generated from the reference geometry data, to determine the geometric deviation therebetween.
In step 414, the controller 22 calibrates the machining system 18 as a function of the geometric deviations. The controller 22, for example, can adjust the workpiece positional data to correct for the geometric deviations between the measured coordinates and the corresponding reference coordinates. In this manner, the machining system 18 can reduce or eliminate future geometric deviation between the workpiece 12 being machined and the workpiece as it is designed.
In step 416, the controller 22 evaluates the geometric deviations to determine whether each workpiece feature 78 machined during step 406 satisfies a workpiece design specification. The workpiece design specification designates a set of geometric design parameters that workpiece features of the workpiece are designed to exhibit. A geometric tolerance for a relative spatial position of a certain point on the surface of the workpiece feature is an example of a geometric design parameter. The geometric deviations may satisfy the workpiece design specification where, for example, the geometric deviation between each of the measured coordinates and each corresponding reference coordinate is less than a respective geometric tolerance. The geometric deviations may not satisfy the workpiece design specification where, for example, one or more of the geometric deviations is greater than the respective geometric tolerances.
In step 418, the controller 22 determines whether to continue the present method as a function of the evaluation in step 416. The controller 22 may terminate the method where, for example, the workpiece feature 78 does not satisfy the workpiece design specification. The controller 22 may continue to the next method step where, for example, the workpiece feature 78 satisfies the workpiece design specification, and (ii) there are one or more additional workpiece features to be machined.
In step 420, the controller 22 repeats steps 404 to 418 to machine and subsequently inspect one or more additional workpiece features. In some embodiments, the additional workpiece features can be iteratively machined and inspected. In other embodiments, the additional workpiece features can be machined together, and subsequently inspected.
Referring again to
While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.
