Method of machining ceramic matrix composite turbine vane blade

Abstract

The processing method of the ceramic matrix composite turbine guider vane of the application comprises the following steps: Cam software is introduced into the blank model of the vane, the vane profile exhaust edge, the transition arc between the vane profile exhaust edge and the two side edge plates are taken as the to-be-polished area, the to-be-polished area is first marked by scribing and is coarsely polished; the A reference surface, the B reference surface, the C reference surface, the edge plate exhaust edge surface and the back radial surface of the coarsely processed blank are milled by the numerical control machine tool; the excess of the vane edge plate basin radial surface and the inlet edge surface is scribed and processed to form the finished product size; the inner circle of the edge plate, the lug and the 72° chamfer of the inner circle edge plate are milled; the vane generatrix for processing the vane profile and the flow channel surface is constructed to mill the vane profile, the flow channel surface and the 71° chamfer of the meridian surface, and the efficiency of the vane milling is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of amorphous alloy technology, and particularly relates to a method for processing turbine guide vanes made of ceramic matrix composite materials. Background Technology

[0002] As one of the most demanding components in an engine, turbine guide vanes not only need to withstand extremely high centrifugal stress, aerodynamic loads, and vibration loads, but also must operate for extended periods in extreme high-temperature environments far exceeding the melting points of traditional metals. Therefore, the field has begun using composite materials to replace traditional metals in the fabrication of turbine guide vanes, seeking superior overall performance in terms of high-temperature resistance, lightweight, and high strength. However, composite materials are often fabricated using a two-dimensional stacking method, resulting in problems such as extremely uneven material distribution, poor surface quality, high hardness, and high brittleness.

[0003] Ceramic matrix materials are strong but brittle, making complex lug structures difficult to process. The novel ceramic matrix composite material used in this patent typically has a density only 1 / 3 to 1 / 4 that of high-temperature alloys, indicating that it possesses high strength and stiffness for the same weight. However, due to the characteristics of its layup process, this material also exhibits high brittleness and is prone to chipping during processing. Therefore, when using traditional methods to process complex lug structures, it is difficult to balance the hardness and brittleness of the new material, resulting in significant processing challenges. The uneven distribution of the ceramic-based material allowance makes it impossible to dynamically adjust the machining datum according to the blade profile. Because the blank in this patent is made of ceramic-based material laid in a two-dimensional manner, the allowance distribution between parts is uneven and inconsistent. If traditional datum machining methods are used, the datum cannot be dynamically adjusted according to the distribution of each blank part, posing a risk of overcutting when machining the blade profile using the datum for positioning. The poor surface quality of ceramic matrix materials means that blade models are often built using a lay-up method, resulting in multiple broken surfaces. This makes it impossible to directly construct the generatrix and flow channel surface elements necessary for CNC machining programming, which increases the difficulty of CNC machining.

[0004] In summary, the efficiency of processing blades is relatively low. Summary of the Invention

[0005] In view of this, the processing method of the ceramic matrix composite turbine guide vane of the present invention solves the technical problem of low processing efficiency of existing processes.

[0006] A method for processing ceramic matrix composite turbine guide vanes, the method comprising, S1: Import the blank model of the blade into the Cam software, and take the blade exhaust edge and the transition arc between the blade exhaust edge and the two side edge plates of the blank model as the polishing area. Mark the polishing area with the first line. The blank model is installed on the processing platform of the polishing machine, and the silicon carbide grinding wheel of the polishing machine is started to perform rough processing on the area to be polished marked by the first scribing.

[0007] S2: Model the rough-machined blank, using the flange exhaust edge of the rough-machined blank as the A reference plane, the perpendicular plane of the blank to the engine axis as the B reference plane, and the reference plane of the blank flange groove near the pan as the C reference plane. The A datum surface, B datum surface, and C datum surface are milled using a CNC machine tool, as well as the venting edge surface and back radial surface of the blank after rough milling. S3: Mark and machine the allowance on the radial surface of the blade edge plate and the intake edge surface to form the finished size; S4: 72° chamfer on the inner circle of the milled edge plate, the lug, and the inner edge plate; S5: Construct the blade generatrix for programming the blade profile and flow channel surface CNC program to mill the 71° chamfer of the blade profile, flow channel surface and meridional surface.

[0008] The beneficial effects of the present invention are as follows: Taking full account of the processing problems brought about by the characteristics of new materials, steps 2 and 3 dynamically adjust the processing datum based on the blade profile allowance distribution to avoid the risk of over-cutting the blade profile. A dynamic processing strategy based on the datum profile is adopted to dynamically adjust the processing datum position according to the allowance distribution of each blade profile blank. Compared with the traditional method of processing the datum profile in one step, this effectively avoids the risk of over-cutting during blade processing. Steps 4 and 5 propose a "dispersed roughing + integrated finishing" processing technology for complex support structures on the blades, significantly improving processing consistency. Dispersed roughing is used for processing the supports, peripheral edge plates, and 72° chamfers. After the allowance is removed, all parts are precision machined in one piece. Compared with the traditional method of roughing and finishing each part separately, this method can significantly improve the surface quality and dimensional accuracy of the blade while taking into account the efficiency of roughing and removing allowance. Compared with traditional methods, it can take into account the hardness and brittleness of the new material, effectively suppress the chipping phenomenon during the processing, and improve the processing qualification rate. At the same time, for the case of raw material made of composite material lay-up with many small fragments and lack of "theoretical generatrix", by establishing and connecting multiple small spline curves, it is possible to build "theoretical generatrix" on the two-dimensional lay-up of ceramic matrix material, so as to achieve the purpose of CNC programming and improve the processing efficiency. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A schematic diagram for the first underline mark; Figure 2 A schematic diagram illustrating dynamic machining based on the blade profile; Figure 3 A schematic diagram for the second underline mark; Figure 4 A schematic diagram of machining a 71° chamfer on the meridional plane of a part; Figure 5 A schematic diagram of fitting the generatrix of the fragment surface; Detailed Implementation The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0011] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0012] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0013] like Figures 1 to 5 The method for processing ceramic matrix composite turbine guide vanes shown includes, S1: Import the blade blank model into the CAM software. The airflow edge of the blank model, and the transition arc between the airflow edge and the two side edge plates, are designated as the areas to be polished. (See...) Figure 1As shown, the area to be polished is marked with the first line; the purpose is to ensure that after processing at the marked line, the chord length allowance and edge plate allowance of each section of the finished product meet the requirement that the single-sided allowance after rough processing is 5±0.5mm. The blank model is installed on the processing platform of the polishing machine. The silicon carbide grinding wheel of the polishing machine is started to perform rough processing on the area to be polished marked by the first scribing mark. For example, the silicon carbide grinding wheel polishes and removes the excess material of the three parts: the exhaust edge of the blade, the exhaust edge and back of the upper edge plate, and the exhaust edge and back side of the lower edge plate in sequence according to the first scribing mark. Ensure that the excess material of each single exhaust edge is 5±0.5mm after polishing. If the scribing is unclear during the polishing process, use a scribing measuring tool to repeat the scribing before polishing.

[0014] S2: See also Figure 2 As shown, the rough-machined blank is modeled, with the flange exhaust edge of the rough-machined blank as datum surface A, the perpendicular plane of the blank to the engine axis as datum surface B, and the datum surface of the flange groove near the diaphragm as datum surface C. Datum surfaces A, B, and C, as well as the flange exhaust edge and back radial surface of the rough-machined blank, are milled using a CNC machine tool. Specifically... S2 includes the CNC machine tool milling of reference surfaces A, B, and C, as well as the rough milling of the blank's venting edge and back radial surface. First, perform machining on datum surfaces A, B, and C. Use special tools (dedicated PCD type tools) to rough machine the three datum surfaces to leave a 0.5mm allowance. A three-coordinate measurement coordinate system is established using datum planes A, B, and C. With datum plane A as the X-axis, datum plane B as the Z-axis, and datum plane C as the Y-axis, a CNC program (e.g., a three-coordinate measurement program) is run to measure the blade profile and flow channel allowance of the machined blades. If the blade allowance distribution is found to meet the processing requirements, the reference processing position is considered to be reasonable, and the A reference surface, B reference surface, and C reference surface are precision milled into place using special PCD tools. If uneven distribution of blade allowance is detected, the machining directions of reference planes A, B, and C are dynamically adjusted in reverse according to the distribution direction of the allowance, and then finely milled to ensure that the theoretical blade shape is evenly distributed in the raw material. After machining the A, B, and C reference surfaces, the CNC machine tool uses PCD special tools to machine the back radial surfaces of the large and small edge plates of the blade and the exhaust edge to the finished size.

[0015] S3: See also Figure 3 As shown, scribing and machining the allowance on the radial surface of the blade rim and the intake side surface to form the finished dimensions, specifically... Based on the marking function of CAM software, the blade is fixed by using a "scribing gauge" and a second scribing mark is made on the basin, radial surface and intake edge of the blade side edge plates to be processed (the thickened area in the figure). This ensures that after processing at the scribing point, the single-sided allowance of the finished edge plate is 5±0.5mm. Using a polishing machine, the processing area marked by the second scribing line is polished in sequence to remove the large excess material on the radial surface of the blade side plate and the exhaust side surface. Ensure that the single-sided excess material after polishing is 5±0.5mm. If the scribing is unclear during the polishing process, the scribing measuring tool can be used to repeat the scribing to complete the rough processing. Using a dedicated R3 PCD tool and milling, the radial surface of the blade's two side edge plates and the exhaust side surface are finished to the final dimensions.

[0016] S4: Milling the inner circle of the edge plate, the lugs, and the 72° chamfer of the inner edge plate. Specifically... The CNC machine tool is equipped with a D10R2.5 dedicated PCD tool to perform rough milling around the lug and the top of the lug. Using a dedicated PCD tool (D10R2.5), the top of the support lug is semi-finished using a free path to ensure a machining allowance of 0.2mm at the top. Using a dedicated R2.5 PCD tool, semi-finishing is performed around the lug by milling to ensure that the allowance around the lug is 0.2mm; Using a dedicated D10R2.5 PCD tool, the lug attachment plate is semi-finished by milling to ensure that the allowance around the lug is 0.2mm; Using a dedicated D10 / R2.5 PCD tool, the 72° chamfer connected to the flange plate is semi-finished by milling to ensure that the allowance around the lug is 0.2mm; Using a dedicated R2.5 PCD tool, the lugs, auxiliary flanges, and connecting chamfers are finished by milling. The rounded top of the lug is finished by milling using a dedicated R2.5 PCD tool.

[0017] S5: Construct the blade generatrix for CNC programming of the blade profile and flow channel surface, to mill the 71° chamfer of the blade profile, flow channel surface, and meridional plane. Because the blade is made of two-dimensional ceramic matrix material, the flow channel surface exhibits a multi-fragmented shape when the part model is generated. Therefore, the theoretical generatrix necessary for CNC programming of blade machining is lacking. To address the generatrix fitting method for the fragmented surface of the three-dimensional model, reducing fragmented surface formation, auxiliary surfaces are first created, then intersected with the "actual flow channel surface" to construct multiple small spline curves. After deleting duplicate spline curves, the remaining spline curves are connected to finally construct the single "theoretical blade generatrix" required for CNC machining programming. The "theoretical flow channel surface" is obtained by rotating around the engine centerline. Specifically... See Figure 5 As shown, the engine's central axis extends beyond the outer circumferential plate flow channel surface, or the Cam software's stretching command is executed to form an auxiliary surface, which is then stretched to form the first set of surfaces; The standard finished blade 3D model's flow channel fragment facets can be expanded using the expand surface command, which can expand along the flow channel rotation direction of the engine axis. The expanded flow channel fragment facets serve as the second set of faces. That is, the flow channel fragment facet parameters are expanded at the V-direction starting point (the V-direction starting point refers to the length and width directions of the fragment facets in the NX12 software command, and the direction in which they are expanded along the flow channel rotation direction of the engine axis). The first and second sets of surfaces are used to construct multiple generatrices by running intersecting curve commands. After the multiple generatrices are modified and trimmed, they are used to form multiple spline generatrices. The multiple spline generatrices are used to run connection programming instructions to form the theoretical generatrices of the blades. The theoretical generatrices of the blades are rotated around the central axis of the engine to form the theoretical flow channel surface. See Figure 4 As shown, the theoretical flow channel surface is milled at the corresponding position of the blade using an R3 dedicated PCD tool to complete the machining of the blade profile and flow channel surface. Then, a 71° chamfer is machined on the meridional surface of the part using a D10 / R2.5 dedicated PCD tool.

[0018] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for processing ceramic matrix composite turbine guide vanes, characterized in that, The processing method includes, S1: Import the blank model of the blade into the Cam software, and take the blade exhaust edge and the transition arc between the blade exhaust edge and the two side edge plates of the blank model as the polishing area. Mark the polishing area with the first line. The blank model is installed on the processing platform of the polishing machine, and the silicon carbide grinding wheel of the polishing machine is started to perform rough processing on the area to be polished marked by the first scribing. S2: Model the rough-machined blank, using the flange exhaust edge of the rough-machined blank as the A reference plane, the perpendicular plane of the blank to the engine axis as the B reference plane, and the reference plane of the blank flange groove near the pan as the C reference plane. The A datum surface, B datum surface, and C datum surface are milled using a CNC machine tool, as well as the venting edge surface and back radial surface of the blank after rough milling. S3: Mark and machine the allowance on the radial surface of the blade edge plate and the intake edge surface to form the finished size; S4: 72° chamfer on the inner circle of the milled edge plate, the lug, and the inner edge plate; S5: Construct the blade generatrix for programming the blade profile and flow channel surface CNC program to mill the 71° chamfer of the blade profile, flow channel surface and meridional surface.

2. The processing method according to claim 1, characterized in that, The silicon carbide grinding wheel of the starting polishing machine in S1 performs rough machining on the area to be polished marked by the first scribe line, including... The silicon carbide grinding wheel is used to polish and remove excess material from three parts in sequence according to the first scribing mark: the exhaust edge of the blade, the exhaust edge and back of the upper edge plate, and the exhaust edge and back side of the lower edge plate. Ensure that the excess material of each exhaust edge is 5±0.5mm after polishing. If the scribing is unclear during the polishing process, use a scribing measuring tool to scribing again before polishing.

3. The processing method according to claim 1, characterized in that, S2 includes the CNC machine tool milling of reference surfaces A, B, and C, as well as the rough milling of the blank's venting edge and back radial surface. First, perform machining on datum surfaces A, B, and C. Use special cutting tools to rough machine the three datum surfaces to leave a 0.5mm allowance. A three-coordinate measurement coordinate system is established using datum planes A, B, and C. With datum plane A as the X-axis, datum plane B as the Z-axis, and datum plane C as the Y-axis, a CNC program is run to inspect the blade profile and flow channel allowance of the machined blades. If the blade allowance distribution is found to meet the processing requirements, use a special PCD tool to finish mill the A, B, and C reference surfaces into place. If uneven distribution of blade allowance is detected, the machining directions of reference planes A, B, and C are dynamically adjusted in reverse according to the distribution direction of the allowance, and then finely milled to ensure that the theoretical blade shape is evenly distributed in the raw material. After machining the A, B, and C reference surfaces, the CNC machine tool uses PCD special tools to machine the back radial surfaces of the large and small edge plates of the blade and the exhaust edge to the finished size.

4. The processing method according to claim 1, characterized in that, Step S3 includes, The marking function of the CAM software is used to perform a second scribing mark on the areas to be processed on the basin, radial surface and air intake edge of the two side edge plates of the blade. Using a polishing machine, the processing area marked by the second scribe line is polished in sequence to remove the large excess material on the radial surface of the blade and the exhaust side surface of the blade side edge plates, ensuring that the single-sided excess material after polishing is 5±0.5mm. Using a dedicated R3 PCD tool and milling, the radial surface of the blade's two side edge plates and the exhaust side surface are finished to the final dimensions.

5. The processing method according to claim 1, characterized in that, Step S4 includes, The CNC machine tool is equipped with a D10R2.5 dedicated PCD tool to perform rough milling around the lug and the top of the lug. The top of the support lug is semi-finished using a free path method to ensure that the top allowance after machining is 0.2mm; The lugs are semi-finished by milling to ensure a allowance of 0.2mm around the lugs; The lug attachment plate is semi-finished by milling to ensure that the allowance around the lug is 0.2mm; The 72° chamfer connected to the flange plate is semi-finished by milling to ensure that the allowance around the support lug is 0.2mm; Using a dedicated R2.5 PCD tool, the lugs, auxiliary flanges, and connecting chamfers are finished by milling. The rounded top of the lug is finished by milling using a dedicated R2.5 PCD tool.

6. The processing method according to claim 1, characterized in that, Step S5 includes, An auxiliary surface is formed by running along the engine's central axis beyond the outer circumferential flange flow channel surface or by executing a stretching command in the Cam software. The auxiliary surface is then stretched to form a first set of surfaces. The flow channel fragment facets of the standard finished blade 3D model can be expanded using the enlarged surface command along the flow channel rotation direction of the engine axis. The expanded flow channel fragment facets serve as the second set of faces. The first group of surfaces and the second group of surfaces use intersecting curve commands to construct multiple generatrices. After modification and trimming, multiple spline generatrices are formed. The multiple spline generatrices are then connected by programming instructions to form the theoretical generatrices of the blades. The theoretical generatrices of the blades are rotated around the central axis of the engine to form the theoretical flow channel surface. The theoretical flow channel surface is milled at the corresponding position of the blade using an R3 dedicated PCD tool to complete the machining of the blade profile and flow channel surface. Then, a 71° chamfer is machined on the meridional surface of the part using a D10 / R2.5 dedicated PCD tool.

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