A high-precision turbine disc mortise and tenon groove slow wire cutting process design method

Abstract

The application provides a high-precision turbine disc mortise slow wire cutting process design method, which comprises the following steps: step 1, selecting a wire cutting device; step 2, verifying the processing precision of the device; step 3, designing a clamping scheme of a test piece; step 4, performing wire cutting rough machining on the test piece; step 5, performing wire cutting fine machining on the test piece, and performing wire cutting machining on the test piece mortise according to the final required shape; step 6, monitoring the deformation of the test piece, selecting axial and radial representative features on the test piece to monitor the size and technical conditions in the machining process, and forming a whole-process record; and step 7, performing wire cutting machining on a formal part according to steps 3-6 of the test piece. The application has the advantages that the process scheme of the application can realize high-precision control of the mortise, the deformation of the part in a free state can be controlled within 0.02 mm, the deformation control state of the part is excellent, and greater value is created.

Description

Technical Field

[0001] This invention relates to the field of aero-engine manufacturing technology, and in particular to a design method for a high-precision turbine disk tenon groove slow wire EDM process. Background Technology

[0002] The turbine disk is the component with the highest thermal and mechanical load in the engine. Therefore, the turbine disk is made of high-hardness, difficult-to-cut high-temperature alloys and powder alloys. Especially for the machining of the tenon and groove, the conventional broaching method has the problem that the residual stress of the part is released after broaching, which leads to the part deforming beyond the tolerance and scrapping. The inability to achieve low-stress, high-precision machining to ensure the tenon and groove are qualified and the overall deformation of the part is controlled has become the key and bottleneck problem that restricts whether the part can be delivered in good condition. Summary of the Invention

[0003] The purpose of this invention is to address the issue that conventional broaching methods for machining the tenon groove of turbine disks suffer from residual stress release during broaching, leading to excessive deformation and scrapping of the parts. This makes it impossible to achieve low-stress, high-precision machining to ensure the tenon groove meets quality standards and control overall part deformation, which is a key bottleneck restricting the delivery of qualified parts. This invention employs a slow wire EDM process for the tenon groove structure, conducting comprehensive testing and engineering verification. This achieves precision manufacturing control of the tenon groove structure while simultaneously implementing low-stress machining, controlling overall part deformation, and ensuring overall machining accuracy. This provides a technological method for low-stress, high-precision machining of key tenon groove mating structures in this family of parts, accurately mastering the core machining technology for key tenon groove mating structures.

[0004] This invention provides a high-precision turbine disk tenon groove slow wire EDM process design method, including the following steps:

[0005] Step 1: Select wire EDM equipment. Choose a wire EDM machine whose machining stroke meets the requirements based on the diameter and height of the part.

[0006] Step 2, Equipment machining accuracy verification. Select a test piece made of the same material as the part, perform wire cutting machining according to the tenon and groove shape required by the design, and test the accuracy according to the design requirements;

[0007] Step 3, test piece clamping scheme design. Select structural components with the same dimensions as the clamping and alignment parts and the tenon and groove machining parts of the final part to design the part clamping scheme, including three parts: machine tool interface, angular position, and clamping parts;

[0008] Step 4: Rough machining of the test piece using wire EDM. A certain allowance is added to the final groove shape of the test piece, and the shape is simplified locally to form a rough shape, which is then machined using wire EDM.

[0009] Step 5: Wire EDM precision machining of the test specimen. The test specimen is machined using wire EDM to achieve the final shape required by the tenon and groove design.

[0010] Step 6: Monitoring wire EDM deformation of the test piece. Representative axial and radial features are selected on the test piece to monitor dimensions and technical conditions during the machining process, creating a complete record.

[0011] Step 7: Wire EDM machining of the final part. Follow steps 3-6 from the test piece to complete the machining of the final part.

[0012] This invention addresses the challenges of machining turbine disk tenons by developing a high-precision slow wire EDM process for tenon machining. This process enables precise control of the tenon structure, low-stress machining, and deformation control of the entire part, ensuring overall machining accuracy.

[0013] Compared with the prior art, the advantages of this invention are:

[0014] Using the process scheme of this invention, high-precision control of the tenon groove can be achieved, and the deformation of the part in its free state can be controlled within 0.02mm. The deformation control of the part is excellent, creating greater value. Attached Figure Description

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0016] Figure 1 Flowchart of a high-precision turbine disk tenon groove slow wire EDM process design method;

[0017] Figure 2 This is a schematic diagram of the device as defined in the present invention.

[0018] Figure 3 This is a schematic diagram of the tenon groove type processed for the test piece used to verify the accuracy of the equipment in this invention case.

[0019] Figure 4 This is a schematic diagram of the tenon and groove clamp connected to the equipment in the present invention.

[0020] Figure 5 This is a schematic diagram of the positioning block used for angular alignment transmission during the processing in this invention example;

[0021] Figure 6 This is a schematic diagram showing the shape of the tenon groove before and after the roughing process in this invention.

[0022] Figure 7 This is a schematic diagram showing the completed machining of all the tenons and grooves in the test piece in this invention case;

[0023] Figure 8 This is a schematic diagram illustrating the selection of measurement locations for the axial and radial directions of a part in an example of the present invention. Detailed Implementation

[0024] The present invention will be further explained below with reference to specific implementation schemes, but it is not limited to the present invention. The structures, proportions, sizes, etc. shown in the accompanying drawings are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0025] This invention addresses the machining of the tenon groove in turbine disks. Conventional broaching methods suffer from residual stress release during broaching, leading to excessive deformation and scrapping. The inability to achieve low-stress, high-precision machining to ensure tenon groove quality and overall part deformation control is a critical bottleneck restricting part delivery. This invention presents a high-precision turbine disk tenon groove slow-wire EDM process design method. This method achieves precise manufacturing control of the tenon groove structure while maintaining low stress during the process, controlling overall part deformation and ensuring overall machining accuracy. It provides a process method for low-stress, high-precision machining of key tenon groove mating structures in subsequent parts of this family, accurately mastering the core machining technology for key tenon groove mating structures. This invention uses a powder alloy turbine disk part of an aero-engine as an example to introduce the high-precision turbine disk tenon groove slow-wire EDM process design scheme. The following description, in conjunction with accompanying drawings and embodiments, further illustrates this invention.

[0026] 1) Select a wire EDM machine. The maximum outer diameter of the part is 580mm, the total height of the part is 319.2mm, and the machining stroke is 600mm. The suitable slow wire EDM machine model is the Sodick ANL600Qs from Japan. Figure 2 ;

[0027] 2) Verification of Equipment Machining Accuracy. A test piece made of the same FGH99 material as the part was selected. The test piece had an outer diameter of Φ200mm, and the groove shape was within the dimensions specified in the design drawing. Wire cutting was performed, and the groove geometric accuracy, groove uniformity, and groove roughness were tested and verified. The test results were as follows: contour accuracy 0.01mm, uniformity 0.02mm, and roughness Ra0.68μm, all meeting the design requirements: contour accuracy 0.05mm, uniformity 0.05mm, and roughness Ra0.80μm. Figure 3 ;

[0028] 3) Design of test piece clamping scheme. Select structural components with the same dimensions as the clamping and alignment parts and the tenon and groove machining parts of the formal parts to design the part clamping scheme, including three parts: machine tool interface, angular position, and clamping part.

[0029] Firstly, considering the equipment structure is a non-rotary table type, the fixture design mainly serves to support the parts and precisely fit with the worktable via bolts. It connects to the machine tool via bolts, supporting the parts, and clamps them with eight pressure plates. To ensure fixture accuracy, surface runout of the fixture is corrected, and the runout should not exceed 0.01mm. The two parts of the fixture must be checked to ensure their heights are consistent, with the height difference controlled within 0.01mm. This completes the part clamping and alignment. Figure 4 ;

[0030] Secondly, the machining area of ​​the part is 360°. For non-rotary table parts, the machining area needs to be completed sequentially according to the wire feed stroke range, with all machining done in the same angular direction. To meet the angular requirements, two evenly distributed precision blind holes are added to the uncut part of the wire-cut tenon groove. Blind holes with a diameter of Φ3.55+0.01+0.005m and a depth of 5mm are designed according to the tenon groove size. Positioning blocks that fit the two precision blind holes are manufactured, with the structure as follows: Figure 5 The alignment reference is transferred by fixing a 3.55mm measuring bar on the part for wire cutting and processing in sections. After the wire cutting is completed, the tenon groove of the blind hole part is processed into the finished groove shape, and all processing is completed to achieve complete part processing.

[0031] 4) Rough machining of the test piece using wire EDM. To avoid deformation and subsequent deviations in groove dimensions and positions caused by machining the final groove shape in one pass, a sufficient allowance is allowed for rough machining using wire EDM. Using the wire-cut groove shape as a reference, a 2mm allowance is evenly left along the groove shape. Simultaneously, considering the Φ0.25mm diameter wire used in the wire EDM process and the tendency for wire breakage at sharp points, the groove shape is simplified to effectively avoid wire breakage and improve machining efficiency. The simplified groove shapes before and after are as follows: Figure 6 ;

[0032] 5) Wire EDM precision machining of the test specimen. The test specimen's tenon and groove are machined using wire EDM to achieve the final required shape. The resulting groove shape is as follows: Figure 7 ;

[0033] 6) Monitoring of wire EDM deformation of test specimens. Representative axial and radial features are selected on the test specimens to monitor dimensions and technical conditions during machining, such as... Figure 8 This creates a complete record of the entire process;

[0034] 7) Wire EDM machining of formal parts. Clamp the parts according to the clamping method of the test piece, perform wire EDM, and monitor the process during the process.

[0035] Matters not covered in this invention are common knowledge.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-precision turbine disc mortise slow wire cutting process design method, characterized in that: The method comprises the following steps: Step 1, selecting a wire cutting device; selecting a wire cutting device with a machining stroke meeting the requirements according to the diameter and height of the part, ensuring that the wire cutting does not interfere in the height direction, and ensuring that the device stroke can complete the machining of the entire area in the diameter direction; Step 2, verifying the machining accuracy of the device; selecting a test piece made of the same material as the part, and performing wire cutting machining according to the design requirements of the mortise and tenon shape, and detecting the accuracy according to the design requirements; Step 3, designing a test piece clamping scheme; selecting a structural part with the same size as the formal part clamping and locating part to design a part clamping scheme, including three parts of machine tool interface, angular position and pressing position; Firstly, the wire cutting device structure is non-rotary table type, the clamp plays the role of supporting the part and precisely cooperating with the workbench through bolts, and the clamp is connected with the machine tool through bolts to support the part, and the part is pressed by 8 pressing plates; in order to ensure the accuracy of the clamp, the surface runout of the clamp is located, and the surface runout is not more than 0.01 mm; the heights of the two parts of the clamp need to be consistent, and the height difference is controlled to be within 0.01 mm, and the part clamping and locating are completed; Secondly, the machining area of the part is 360°, and the machining area of the non-rotary table type part needs to be completed in sequence according to the stroke range of the wire, and the same angular direction is completed, in order to meet the angular requirement, two uniform and precise blind holes are added in the uncut part of the wire cutting mortise and tenon, the blind hole with a diameter of Φ3.55+0.01+0.005 m and a depth of 5 mm is designed according to the size of the mortise and tenon, the positioning block matched with the two precise blind holes is manufactured, the 3.55 mm measuring rod is fixed on the part, the locating reference for wire cutting and regional machining is transmitted, and after the wire cutting is completed, the mortise and tenon part of the blind hole is machined to complete the groove type, the whole machining is completed, and the complete machining of the part is realized; Step 4, rough opening machining of the test piece by wire cutting; the final groove type of the test piece is offset by 1-2 mm in size and simplified in local shape to form a rough opening shape, and wire cutting machining is performed; In order to avoid deformation release caused by machining the final groove type by wire cutting once, the wire cutting rough opening is sufficient, the groove type is taken as a reference, 2 mm is uniformly left along the groove type, and the diameter of the wire cutting wire is Φ0.25 mm; in combination with the machining characteristics that the local sharp point part of the wire cutting is easy to break the wire, the groove type is simplified, and the sharp corner part structure of the existing groove type is removed; Step 5, wire cutting fine cutting machining of the test piece; the final required shape of the test piece mortise and tenon is machined by wire cutting; Step 6, wire cutting deformation monitoring of the test piece; the size and technical conditions in the machining process are monitored by selecting the axial and radial representative features on the test piece, and the whole process record is formed; Step 7, wire cutting machining of the formal part; the formal part is machined according to steps 3-6 of the test piece.

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