Blade tip chamfering method

Abstract

This invention discloses a method for machining blade tips. First, based on the blade design drawing, the angle θ between the blade tip and the horizontal plane when the engine axis is horizontal, and the angle r between the engine axis and the chord line of the selected positioning section of the blade, are obtained. Then, the yaw angle α and the torsional angle β are calculated using tgα = tgθ * cos r and tgβ = tgθ * sin r, respectively. Next, the blade is clamped onto a four-axis milling machine. Using the calculated yaw angle α and torsional angle β, the blade is rotated twice with the help of a fixture, so that the tangent line of the blade tip is parallel to the XY plane of the four-axis milling machine's coordinate system, and the vertical projection of the tangent line of the blade tip into the XY plane is parallel to the X-axis. Then, the milling of the blade tip begins. This invention can quickly achieve the clamping angle of the blade on the machine tool, improving the cutting efficiency of the blade tip.

Description

Technical Field

[0001] This invention belongs to the field of blade processing technology, specifically a method and fixture for blade tip trimming. Background Technology

[0002] As the performance of aero-engine blades continues to improve, the requirements for the machining accuracy of blade profiles are becoming increasingly stringent. The dimensional accuracy of the blade tip profile directly affects the airflow of the engine, and the increasing demand for blades also places higher demands on blade tip trimming methods and equipment.

[0003] Compressor rotor blades of various types are usually divided into nine stages. When machining blades of different stages, it is necessary to change the corresponding tooling and readjust the machining coordinate system, which results in a long adjustment time. Summary of the Invention

[0004] The present invention aims to provide a blade tip trimming processing device and processing method, which improves the trimming accuracy of blade tips, reduces machine tool idle rate, realizes quick change of processing device when milling blade tips of different levels of blades, and avoids spending a lot of time and effort to calibrate the coordinate system of different levels.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] The blade tip trimming process includes the following steps.

[0007] Step 1: Obtain the two angle parameters of the blade to be processed based on the blade design part drawing, namely:

[0008] The angle θ between the blade tip and the horizontal plane when the blade is horizontal along the engine axis;

[0009] The angle r between the engine axis and the chord of the selected positioning section of the blade;

[0010] Step 2: Calculate the yaw angle α and the torsional angle β according to the formulas tgα=tgθ*cos r and tgβ=tgθ*sin r respectively;

[0011] Step 3: Mount the blade onto the four-axis milling machine. Perform two rotation operations on the blade according to the yaw angle α and torsion angle β calculated in Step 2, so that the tangent line of the blade tip is parallel to the XY plane of the machine tool coordinate system of the milling machine, and the vertical projection of the tangent line of the blade tip in the XY plane of the machine tool coordinate system is parallel to the X-axis. Then start the milling process of the blade tip.

[0012] Alternatively, in step three, the blade tip trimming fixture is used to rotate the blade by adjusting the yaw angle α and the torsion angle β. The blade tip trimming fixture is mounted on a platform on a conventional milling machine corresponding to the XY plane of the machine tool coordinate system.

[0013] Alternatively, in step three, the blade's yaw angle α rotation is achieved using a blade tip trimming fixture, and the blade's torsional angle β rotation is achieved using the A-axis of a four-axis milling machine.

[0014] Alternatively, the blade tip trimming fixture includes a base plate, which includes a bottom surface, a side surface, and a top surface. The bottom surface and the top surface are connected by two parallel, spaced-apart side surfaces. The angle between the bottom surface and the top surface is equal to the torsion angle β. A blade clamping mechanism is provided on the top surface. When the blade is mounted on the blade clamping mechanism, the angle between the blade's Z-axis and the side surface is equal to the yaw angle α.

[0015] Alternatively, the blade tip trimming fixture includes:

[0016] The base plate includes a bottom surface, side surfaces, and a top surface. The bottom surface and the top surface are connected by two parallel, spaced-apart side surfaces. The bottom surface and the top surface are perpendicular to each other. A blade clamping mechanism is provided on the top surface. When the blade is mounted on the blade clamping mechanism, the angle between the Z-axis of the blade and the side surface is equal to the yaw angle α.

[0017] The tray is attached to one side of the base plate, has multiple connection holes, and the base plate is connected to the A-axis of the four-axis milling machine via the tray.

[0018] Furthermore, the blade clamping mechanism includes a blade clamping unit and a blade support unit.

[0019] Compared with the prior art, the present invention provides a method for blade tip trimming and designs a special fixture for milling blade tips at each stage. The base plate of the fixture is fixed to the spindle of a four-axis milling machine after being connected to a universal pallet, or installed on the machining platform of a conventional milling machine after being connected to a pressure plate, thereby ensuring the relative relationship between the workpiece machining coordinate system and the machine tool machining reference system. When changing the machined blade, only the corresponding base plate and pallet or base plate needs to be replaced.

[0020] The blade processing method and processing apparatus of the present invention have the following characteristics:

[0021] (1) This invention calculates a suitable blade processing angle and uses the trigonometric function relationship between the true tilt angle and the apparent tilt angle (i.e., the yaw angle α and the torsion angle β are used as the apparent tilt angle, and the angle θ between the blade tip and the horizontal plane when the blade is horizontal on the engine axis is used as the true tilt angle) to adjust the placement position of the blade to be processed on the machine tool, thereby facilitating the clamping and alignment of the blade and meeting the processing requirements of the blade.

[0022] (2) This invention provides two angle adjustment schemes. One scheme utilizes a fixture that simultaneously includes the yaw angle and the torsion angle. The disadvantage of this scheme is that the fixture structure is relatively complex and the number of fixtures is large (a set needs to be configured for different blade specifications). Due to the difficulty in machining and fixing the fixture, the machining accuracy of the blade cannot be guaranteed (the fixture needs to be fixed by pressure plates and screws, which affects the machining accuracy). However, the advantage is that a regular milling machine can be used. The other solution is that the fixture only includes the yaw angle, and the torsion angle is achieved by rotating the spindle of a four-axis milling machine connected to the fixture. In comparison, this scheme only needs to consider one yaw angle, so the machining of the fixture is simpler, and the spindle rotation adjustment accuracy of the four-axis milling machine is higher. This helps to reduce the number of fixtures, improve the machining accuracy, and facilitate quick fixture changes for different blade specifications. The disadvantage is that a four-axis milling machine is required.

[0023] (3) When a fixture design that only includes the yaw angle is adopted, the fixture and the four-axis milling machine are detachably connected, which can realize the rapid switching of the fixture for each stage of blade processing, with high efficiency and guaranteed accuracy. Especially when it comes to the processing of multi-stage blades, there is no need to recalibrate the processing coordinate system, which shortens the machine tool's idle time and makes the changeover quick and accurate. Attached Figure Description

[0024] Figure 1 This is a drawing of a blade tip trimming part involved in the processing of this invention;

[0025] Figure 2 This is a diagram of the pallet component in this invention;

[0026] Figure 3 This is a schematic diagram of a clamp that includes both a yaw angle and a torsion angle in this invention;

[0027] Figure 4 This is a schematic diagram of a fixture in this invention that only includes the yaw angle and connects to the machine tool A-axis via a pallet;

[0028] In the figure, 1-base plate; 2-tray; 3-blade clamping unit; 4-blade body support unit. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0030] like Figure 2 and Figure 4 As shown, this is a clamp in the present invention that only includes the deflection angle, wherein, Figure 2 The structure of tray 2 is shown. Figure 4 The connection between the base plate 1 and the tray 2 in the processing device is shown. The tray 2 is a cube with 6 through holes machined on its surface. The side of the base plate 1 is also machined with multiple threaded holes. The tray 2 is connected to the A-axis of the four-axis milling machine through the through holes using screws.

[0031] like Figure 3 As shown, this is a clamp in the present invention that simultaneously includes a yaw angle and a torsion angle. Figure 3 As can be seen, the base plate 1 includes the two angles required for blade tip machining: the yaw angle α and the torsion angle β. The left and right sides of the base plate 1 are pressed against the worktable of a conventional milling machine by pressure plates. For comparison, as shown... Figure 4 As shown, the torsion angle β is omitted on the base plate 1, and only the yaw angle α is retained. The torsion angle β is achieved by rotating the A-axis of the four-axis milling machine, but a tray 2 structure connected to the four-axis milling machine is added.

[0032] like Figure 1 As shown, the blade tip tangent is first horizontalized to obtain the blade engine axis in this state. Figure 1 The angle θ between the center arrow (N direction) and the horizontal plane, and the angle r between the engine axis and the chord of the selected positioning section of the blade, are used to calculate the yaw angle α and the torsional angle β according to the formulas tgα = tgθ * cos r and tgβ = tgθ * sin r, respectively. Based on the calculation results of the yaw angle α and the torsional angle β, a design is then developed. Figure 3 and Figure 4 The fixture. Among them, the blade clamping unit 3 and the blade support unit 4 on the top surface of the fixture are conventional solutions, which only need to ensure that they include the yaw angle α and the torsion angle β.

[0033] When using Figure 3 When machining blades of different grades using a fixture, follow these steps:

[0034] Step 1: For blades of different grades, select a base plate 1 with the same yaw angle α and torsion angle β according to the yaw angle α and torsion angle β required for blade tip processing.

[0035] Step 2: After clamping the blade onto the blade clamping unit 3 and the blade body support unit 4 on the base plate 1, the fixture is fixed on the machining platform of the ordinary milling machine by the pressure plate on the side of the base plate 1.

[0036] Step 3: Process the blade tips of this grade;

[0037] Step 4: After completing the machining of this stage of blades, remove the base plate 1 from the machining platform and repeat Step 1 to perform machining of another stage of blades.

[0038] The advantage of this solution is that it can be applied to ordinary milling machines, but the disadvantage is that when switching between different levels of blades, it needs to be readjusted, which is time-consuming and labor-intensive.

[0039] When using Figure 4 When machining blades of different grades using a fixture, follow these steps:

[0040] Step 1: For blades of different grades, select a base plate with the same deflection angle α according to the deflection angle α required for blade tip processing;

[0041] Step 2: After clamping the blade onto the blade clamping unit 3 and blade body support unit 4 on the base plate 1, connect the base plate 1 to the rotary spindle (A-axis) of the four-axis milling machine through the tray 2 on the side of the base plate 1.

[0042] Step 3: Obtain the torsion angle β required for blade tip machining by rotating the spindle (A-axis) of the four-axis milling machine, and machine the blade tip of this stage;

[0043] Step 4: After completing the machining of this stage of blades, remove tray 2 and base plate 1 from the rotary spindle (A-axis) of the four-axis milling machine (remove the screws used for connection in the through hole), and repeat step 1 to perform machining of another stage of blades.

[0044] This solution makes full use of the rotation center of the machine tool spindle, omits the torsion angle β of the base plate 1, simplifies the structure of the base plate 1 in the machining device, and improves machining accuracy. More importantly, machining different stages of blades does not require recalibrating the machining coordinate system, shortens the machine tool's idle time, and allows for quick and precise changeovers.

[0045] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A method of tip skiving a blade, characterized in that Includes the following steps: Step 1: Obtain the two angle parameters of the blade to be processed based on the blade design part drawing, namely: The angle θ between the blade tip and the horizontal plane when the blade is horizontal along the engine axis; The angle r between the engine axis and the chord of the selected positioning section of the blade; Step 2: Calculate the yaw angle α and the torsion angle β according to the formulas tgα=tgθ*cos r and tgβ=tgθ*sin r respectively; Step 3: Mount the blade onto the milling machine and rotate it twice according to the yaw angle α and torsion angle β calculated in Step 2. This will make the tangent line of the blade tip parallel to the XY plane of the milling machine's coordinate system, and the vertical projection of the tangent line of the blade tip in the XY plane of the milling machine's coordinate system parallel to the X-axis. Then, begin the milling process of the blade tip.

2. The method according to claim 1, wherein: In step three, the blade tip trimming fixture is used to rotate the blade by adjusting the yaw angle α and the torsion angle β. The blade tip trimming fixture is mounted on a platform on a conventional milling machine corresponding to the XY plane of the machine tool coordinate system.

3. The method of claim 1, wherein: In step three, the blade's yaw angle α is rotated using a blade tip trimming fixture, and the blade's torsional angle β is rotated using the A-axis of a four-axis milling machine.

4. The blade tip trimming method according to claim 2, characterized in that: The blade tip trimming fixture includes a base plate (1), which includes a bottom surface, a side surface and a top surface. The bottom surface and the top surface are connected by two parallel and spaced side surfaces. The angle between the bottom surface and the top surface is equal to the torsion angle β. A blade clamping mechanism is provided on the top surface. When the blade is installed on the blade clamping mechanism, the angle between the Z-axis of the blade and the side surface is equal to the yaw angle α.

5. The blade tip trimming method according to claim 3, characterized in that, The blade tip trimming fixture includes: The base plate (1) includes a bottom surface, a side surface and a top surface. The bottom surface and the top surface are connected by two parallel and spaced side surfaces. The bottom surface and the top surface are perpendicular to each other. A blade clamping mechanism is provided on the top surface. When the blade is installed on the blade clamping mechanism, the angle between the Z-axis of the blade and the side surface is equal to the yaw angle α. The tray (2) is connected to one side of the base plate (1). The tray (2) has multiple connection holes, and the base plate (1) is connected to the A-axis of the four-axis milling machine through the tray (2).

6. The blade tip trimming method according to claim 5, characterized in that: The blade clamping mechanism includes a blade clamping unit (3) and a blade support unit (4).

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