A boss machining method for a thin-walled curved surface titanium alloy blade

Abstract

The application discloses a boss processing method for a thin-wall curved-surface titanium alloy blade, and comprises the following steps: placing a clamping tool with a zero-position positioning system on an A-axis of a five-axis machining center, clamping a tenon of the thin-wall curved-surface titanium alloy blade to a tenon tooth of the clamping tool; controlling a pneumatic button, pneumatically jacking the tenon position, and starting a hydraulic device to perform hydraulic auxiliary support on a blade body; after a first tool-path is generated, performing rough grinding on the boss of the thin-wall curved-surface titanium alloy blade; and after a second tool-path is generated, performing fine grinding on the boss of the thin-wall curved-surface titanium alloy blade. The method has high processing efficiency and high processing quality.

Description

Technical Field

[0001] This invention belongs to the field of blade processing technology, and specifically relates to a method for processing bosses on thin-walled curved titanium alloy blades. Background Technology

[0002] During long-term service, the boss blades will wear down. To effectively ensure the fit between the low-pressure rotor blades, the dimensions of the boss need to be restored to the requirements of the original drawing design, with a dimensional machining tolerance of ≤0.05 mm, a surface spatial angle tolerance of ±10′, and a maximum blade wall thickness of only about 2 mm near the machined boss. Therefore, the blade rigidity is relatively poor during the boss grinding process.

[0003] Currently, when machining boss blades, surface grinders are used for dry grinding of the bosses. The measurement method is off-machine inspection, and the machining and measurement are not on the same set of tooling. The blade size and spatial position angle are adjusted by the operator and guaranteed by the tooling. Often, multiple grinding, measurement and adjustment are required to achieve the qualified size. The machining efficiency is low and the machining quality needs to be further improved. Summary of the Invention

[0004] To address the problems of low processing efficiency and low processing quality in existing methods, this invention provides a method for machining bosses on thin-walled curved titanium alloy blades, which has high processing efficiency and high processing quality.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention discloses a method for machining bosses on thin-walled curved titanium alloy blades, comprising the following steps:

[0007] Place the clamping fixture with zero-point positioning system on the A-axis of the five-axis machining center, and clamp the tenon of the thin-walled curved titanium alloy blade to the tenon teeth of the clamping fixture.

[0008] Control the pneumatic button to pneumatically tighten the tenon, and activate the hydraulic device to provide hydraulic auxiliary support for the blade.

[0009] The width of the boss on the thin-walled curved titanium alloy blade is measured using a Renishaw probe and fed back to the CNC system so that the CNC system can determine the grinding allowance and generate the first tool path.

[0010] The five-axis machining center uses a flat cubic boron nitride grinding wheel and SY910 cutting fluid to rough grind the bosses of the thin-walled curved titanium alloy blades according to the grinding allowance and along the first tool path;

[0011] The dimensions of the boss on the thin-walled curved titanium alloy blade and the deviation values ​​of the boss surface in the X and Y directions are measured. The allowances for angle and size are calculated and fed back to the CNC system so that the CNC system can determine the second tool path.

[0012] After adjusting the angle of the sheet-shaped cubic boron nitride grinding wheel, the five-axis machining center completes the precision grinding of the boss of the thin-walled curved titanium alloy blade according to the allowance and along the second tool path.

[0013] Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0014] This invention is based on a five-axis machining center to process the bosses of thin-walled curved titanium alloy blades. During processing, the blades are fixed by clamping fixtures, and cutting fluid is added during cutting. The bosses are first rough ground and then fine ground, which improves both processing efficiency and processing quality. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of a thin-walled curved titanium alloy blade;

[0017] Figure 2 This is an enlarged view of the boss on a thin-walled curved titanium alloy blade.

[0018] Figure 3 A schematic diagram of the structure for mounting thin-walled curved titanium alloy blades to a clamping fixture. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] This invention discloses a method for machining bosses on thin-walled curved titanium alloy blades, which is implemented using a five-axis machining center. Specifically, the method includes steps S01 to S07.

[0026] Step S01: Measure the width of the boss on the thin-walled curved titanium alloy blade and determine the accuracy of the measurement data.

[0027] Based on the dimensions and positional relationships of the blade drawings, a machine tool measurement program was written. The Renishaw probe built into the five-axis machining center was used to measure the width of the boss. To ensure that no batch grinding errors caused by measurement mistakes occurred during the grinding and measurement process, the dimensions were first confirmed using inspection parts. The data from the inspection parts were based on the coordinate measuring machine (CMM) results, and the measurement cycle was one year. If the error was ≤0.005 mm, the measurement data was considered correct, and the product grinding work began.

[0028] Step S02: Place the clamping fixture with zero-point positioning system on the A-axis of the five-axis machining center, and clamp the tenon of the thin-walled curved titanium alloy blade 1 to the tenon teeth of the clamping fixture.

[0029] Preferably, flexible fixtures are used for clamping. The mounting structure of the zero-point positioning system 3, clamping fixture 2, thin-walled curved titanium alloy blade, and tailstock 4 is as follows: Figure 3 As shown. The overall structure of the thin-walled curved titanium alloy blade is referenced. Figure 1 For an enlarged view of the location of the boss that needs to be machined, please refer to [the image / diagram / reference]. Figure 2 .

[0030] Step S03: Control the pneumatic button to pneumatically tighten the tenon position, and activate the hydraulic device to provide hydraulic auxiliary support for the blade.

[0031] This step involves clamping the blade tenon to the tooling tenon, using pneumatic tenon positioning in conjunction with hydraulic auxiliary support for the blade body for rapid positioning and flexible clamping. This avoids clamping deformation and grinding chatter during the blade grinding process, thereby improving the quality of blade processing.

[0032] Step S04: Use a Renishaw probe to measure the width of the boss on the thin-walled curved titanium alloy blade and feed it back to the CNC system so that the CNC system can determine the grinding allowance and generate the first tool path.

[0033] Step S05: The five-axis machining center uses a flat cubic boron nitride grinding wheel and SY910 cutting fluid to rough grind the boss of the thin-walled curved titanium alloy blade according to the grinding allowance and along the first tool path.

[0034] Because the thin-walled curved titanium alloy blades are made of titanium alloy, they are easily contaminated and burned by low-melting-point alloys during machining. Therefore, in this step, SY910 cutting fluid is added during rough grinding, and the grinding parameters are improved to enhance the machining quality of the thin-walled curved titanium alloy blades.

[0035] Currently, the machining of thin-walled curved titanium alloy blades uses ordinary cutting tools, which can interfere with the clamping fixtures during the machining process. To improve blade machining quality and avoid interference with the clamping fixtures, a blade-shaped cubic boron nitride (CBN) abrasive wheel is used, with one end serving as the tool holder. The cutting action of the CBN abrasive wheel is controlled by controlling the tool holder. The grinding force of the CBN abrasive wheel is much greater than that of materials such as diamond and silicon carbide, allowing for precise control of the post-grinding dimensions and preventing issues such as insufficient material feeding, grinding compression, and blade burning, thus further improving the blade machining quality.

[0036] To improve machining quality, the boron nitride in the flake cubic boron nitride grinding wheel has a diameter of 30 mm and a grit size of 80 mesh, meeting the requirement of a surface roughness ≤ Ra 0.8 μm after grinding. The flake cubic boron nitride grinding wheel material meets the anti-contamination requirements for titanium alloy parts, does not contaminate the titanium alloy material, and has good grinding force.

[0037] Furthermore, in this step, the control parameters for the sheet-shaped cubic boron nitride grinding wheel are: rotational speed 2000 r / min, feed rate 1500 mm / min, and depth of cut 0.05 mm.

[0038] Step S06: Measure the dimensions of the boss on the thin-walled curved titanium alloy blade and the X and Y direction deviation values ​​of the boss surface, calculate the allowance of angle and dimension and feed it back to the CNC system so that the CNC system can determine the second tool path.

[0039] Since the angle is not easy to measure, the angle is calculated by measuring the deviation values ​​in the X and Y directions of the boss surface.

[0040] See the X and Y directions of the boss surface. Figure 2 As shown in the image.

[0041] Step S07: After adjusting the sheet-shaped cubic boron nitride grinding wheel according to the angle, the five-axis machining center completes the precision grinding of the boss of the thin-walled curved titanium alloy blade according to the allowance and along the second tool path.

[0042] During fine grinding, the machining state diagram of the sheet-like cubic boron nitride grinding wheel 1 and the boss is shown below. Figure 3 As shown.

[0043] Similar to step S05, during fine grinding, cutting fluid of grade SY910 is added, and the control parameters of the sheet-shaped cubic boron nitride grinding wheel are set as follows: grinding wheel speed 3000 r / min, feed rate 2000 mm / min, and depth of cut 0.01 mm.

[0044] Before fine grinding, only the angle of the flat cubic boron nitride grinding wheel needs to be finely adjusted to compensate for the angle.

[0045] After fine grinding, a final measurement is required. Once the measurement is confirmed to be correct, the blade grinding process is completed, and the next blade to be processed is replaced.

[0046] For example, the above method is used to machine the boss on a thin-walled curved titanium alloy blade. Step S04 determines the grinding allowance to be 0.8 mm. The dimensional allowance obtained in step S06 includes the dimensional allowance, an X-direction deviation of 0.10 mm, and a Y-direction deviation of 0.02 mm. The process requires the X-direction deviation to be ≤0.02 mm and the Y-direction deviation to be ≤0.01 mm. The automatic grinding software feeds back the allowance and angle values ​​to the CNC program based on spatial relationships to generate a fine grinding toolpath. Using this method, the machined blades exhibit high quality and high efficiency.

[0047] Using the above method, the original method of one person measuring and one person grinding has been changed to one person on duty who only needs to change the blades, without having to leave the machine to measure, saving 50% of labor costs; the original method of manually adjusting and processing 3 to 5 times to achieve the drawing dimensions has been improved to a 100% pass rate after grinding.

[0048] During the grinding process, coolant was added to prevent the titanium alloy blade surface from overheating and burning.

[0049] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for machining bosses on thin-walled curved titanium alloy blades, characterized in that, Includes the following steps: Place the clamping fixture with zero-point positioning system on the A-axis of the five-axis machining center, and clamp the tenon of the thin-walled curved titanium alloy blade to the tenon teeth of the clamping fixture. Control the pneumatic button to pneumatically tighten the tenon position, and activate the hydraulic device to provide hydraulic auxiliary support for the blade body. Specifically, clamp the blade tenon to the tooling tenon, and use the pneumatic tenon positioning combined with the hydraulic auxiliary support of the blade body for rapid positioning and flexible clamping. The width of the boss on the thin-walled curved titanium alloy blade is measured using a Renishaw probe and fed back to the CNC system so that the CNC system can determine the grinding allowance and generate the first tool path. The five-axis machining center uses a flat cubic boron nitride grinding wheel and SY910 cutting fluid to rough grind the bosses of the thin-walled curved titanium alloy blades according to the grinding allowance and along the first tool path; The dimensions of the boss on the thin-walled curved titanium alloy blade and the deviation values ​​of the boss surface in the X and Y directions are measured. The allowances for angle and size are calculated and fed back to the CNC system so that the CNC system can determine the second tool path. After adjusting the angle of the sheet-shaped cubic boron nitride grinding wheel, the five-axis machining center completes the precision grinding of the boss of the thin-walled curved titanium alloy blade according to the allowance and along the second tool path.

2. The method for machining the boss of a thin-walled curved titanium alloy blade according to claim 1, characterized in that: Before the tenon of the thin-walled curved titanium alloy blade is clamped to the tenon of the clamping fixture, the following steps are also included: Measure the width of the boss on a thin-walled curved titanium alloy blade and determine the accuracy of the measurement data.

3. The method for machining the boss of a thin-walled curved titanium alloy blade according to claim 1, characterized in that: During rough grinding, the control parameters for the flake-shaped cubic boron nitride grinding wheel are: Rotational speed 2000 r / min, feed rate 1500 mm / min, depth of cut 0.05 mm.

4. The method for machining the boss of a thin-walled curved titanium alloy blade according to claim 1, characterized in that: During fine grinding, The control parameters for the sheet-like cubic boron nitride grinding wheel are: The grinding wheel speed is 3000 r / min, the feed rate is 2000 mm / min, and the depth of cut is 0.01 mm.

5. The method for machining the boss of a thin-walled curved titanium alloy blade according to claim 1, characterized in that: The cutting fluid has a concentration of 3% to 6% and a pH value of 8.5 to 9.

5.

6. The method for machining the boss of a thin-walled curved titanium alloy blade according to claim 1, characterized in that: The sheet-shaped cubic boron nitride grinding wheel is sheet-shaped, and the boron nitride has a diameter of 30 mm and a particle size of 80 mesh.

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