Methods and systems for wire electric discharge machining and validation of parts

Patent metadata

Field	Value
Publication number	US-11554433-B2
Application number	US-201916585623-A
Country	US
Kind code	B2
Filing date	Sep 27, 2019
Priority date	Sep 27, 2019
Publication date	Jan 17, 2023
Grant date	Jan 17, 2023

Abstract

A method of wire electric discharge machining (wEDM) a feature in a part includes using wEDM, cutting and detaching a slug from a portion of the part that is to be detached from the part to define the feature, and thereby defining a validation cut-out in the portion, and using wEDM, cutting and detaching the portion having the validation cut-out from the part and thereby defining the feature.

First claim

The invention claimed is:

1. A method of wire electric discharge machining (wEDM) a feature in a part, comprising:
using wEDM, cutting and detaching a slug from a portion of the part that is to be detached from the part to define the feature, and thereby defining a validation cut-out in the portion; and
using wEDM, cutting and detaching the portion having the validation cut-out from the part and thereby defining the feature,
retaining both the slug and the portion once detached; and
conducting a metallurgical analysis process on the slug and/or the portion.

2. The method of claim 1 , wherein the feature is a fir-tree shaped slot, and the validation cut-out is fir-tree shaped.

3. The method of claim 1 , wherein the validation cut-out has a surface, and the cutting and detaching the slug includes executing a plurality of wEDM passes along the surface to give the surface a surface finish.

4. The method of claim 3 , comprising using wEDM, cutting a plurality of features in the part by executing respective additional iterations of the plurality of wEDM passes with respect to each of the features to give a surface of each of the features the surface finish of the surface of the validation cut-out, the feature being one of the features.

5. The method of claim 4 , wherein the step of cutting and detaching the slug is executed using a wEDM machine and the step of cutting the features is executed using the wEDM machine.

6. The method of claim 4 , wherein the plurality of wEDM passes executed to define the surface of the validation cut-out executed by the wEDM machine using a set of wEDM cutting parameters, and the respective additional iterations of the plurality of wEDM passes are executed using the set of wEDM cutting parameters.

7. The method of claim 6 , comprising:
determining a set of characteristics of a surface of the validation cut-out; and
where the determined set of characteristics meets a set of threshold characteristics associated with the part, designating the feature in the part as acceptable, and else, designating the feature in the part as unacceptable.

8. The method of claim 7 , wherein the step of determining the set of characteristics includes executing a cleaning process with respect to the portion of the part.

9. The method of claim 7 , wherein the step of determining the set of characteristics includes analyzing the surface of the validation cut-out after the step of executing the cleaning process.

10. The method of claim 7 , wherein the step of determining the set of characteristics includes executing the metallurgical analysis process with respect to the portion of the part.

11. The method of claim 10 , wherein the metallurgical analysis process includes cutting the portion of the part into multiple parts.

12. A method of defining a plurality of slots in a turbine disc, the slots being fir-tree shaped and having respective given locations in the turbine disc, comprising, using a wEDM machine:
executing a roughing pass to define a fir-tree shaped validation cut-out in the turbine disc in the given location of a given slot of the slots, the validation cut-out having a validation surface;
executing at least one additional pass along the validation surface to give the validation surface a surface finish;
wEDM the slots in the turbine disc in respective ones of the given locations by executing respective iterations of the roughing pass with respect to the slots, the step of wEDM the slots removing from the turbine disc a portion of the turbine disc having the validation cut-out;
executing respective iterations of the at least one additional pass along surfaces of the turbine disc defining the slots to give the surfaces of the turbine disc the surface finish, and
after a cleaning process followed by a chemical analysis have been completed with respect to the portion of the turbine disc having the validation cut-out, and in response to determining that the set of results of the chemical analysis meets a threshold set of chemical results associated with the portion of the turbine disc, executing a metallurgical analysis process with respect to the portion of the turbine disc.

13. The method of claim 12 , comprising in response to determining that a set of results of the metallurgical analysis meets a threshold set of metallurgical results associated with the portion of the turbine disc, designating the turbine disc as acceptable for further processing.

14. A system for machining a plurality of slots in a turbine disc, the slots being fir-tree shaped and having respective given locations in the turbine disc, comprising:
a wEDM machine configured to removably engage the turbine disc for wEDM features into the turbine disc; and
a controller in communication with the wEDM machine, the controller comprising a processor and a non-transitory memory operatively connected to the processor, the non-transitory memory storing a technology file that includes therein wEDM parameters and processor-executable instructions in the non-transitory memory, the processor-executable instructions, when executed by the processor while the turbine disc is engaged to the wEDM machine, causing the processor to control the wEDM machine using the wEDM parameters to:
execute a roughing pass to remove a portion of the turbine disc from the given location of a given slot of the slots to define a fir-tree shaped validation surface disposed inward of a fir-tree shape of the given slot;
execute at least one additional pass along the fir-tree shaped validation surface to give the fir-tree shaped validation surface a surface finish; and
machine the slots in the turbine disc in respective ones of the given locations of the slots by executing respective additional iterations of the roughing pass followed by respective additional iterations of the at least one additional pass,
the step of the executing a given roughing pass of the respective additional iterations of the roughing pass removing from the turbine disc a portion of the turbine disc having the fir-tree shaped validation surface without altering the fir-tree shaped validation surface, and retaining the portion removed from the turbine disc for metallurgical analysis, and
the step of the executing the respective additional iterations of the at least one additional pass giving surfaces of the turbine disc defining the slots the surface finish.

15. The system of claim 14 , wherein the non-transitory memory stores therein a technology file that includes wEDM parameters, and the processor-executable instructions, when executed by the processor while the turbine disc is engaged to the wEDM machine, cause the processor to process the technology file to control the wEDM machine to execute all of: a) the roughing pass to remove the portion of the turbine disc, b) the at least one additional pass along the fir-tree shaped validation surface, c) the respective additional iterations of the roughing pass, and d) the respective additional iterations of the at least one additional pass.

16. The system of claim 15 , wherein:
the wEDM parameters include: roughing pass parameters, and post-roughing pass parameters; and
the processor-executable instructions, when executed by the processor while the turbine disc is engaged to the wEDM machine, cause the processor to process the technology file to control the wEDM machine to execute:
both steps a) and c) according to the roughing pass parameters, and both steps b) and d) according to the post-roughing pass parameters.

17. The system of claim 16 , wherein the at least one additional pass includes a finishi

Assignees

• Pratt & Whitney Canada

Inventors

• Ing Visal
• Hardy Ghislain
• Jean Joel

Classifications

• F01D5/3007

  of axial insertion type · CPC title

• B23H7/20 Primary

  for program control, e.g. adaptive · CPC title

• F05D2230/11

  by electrochemical methods · CPC title

• B23H9/10 Primary

  Working turbine blades or nozzles · CPC title

• B23H7/02

  Wire-cutting · CPC title