A method for controlling the machining process deformation of a rectifier

Abstract

The application provides a machining process deformation control method of a rectifier, which can control deformation in the machining process of the rectifier. The method controls deformation through a blade milling angle compensation method during blade milling of the rectifier. The blade milling angle compensation is that, during the machining, the machining coordinate angle is rotated for the blade on the air outlet side when the actual position of the blade on the air inlet side is considered, the rotation direction is the deflection direction of the blade, and the blade milling is performed by using the rotated machining coordinate. The rotation angle C of the blade milling angle compensation is B*180 / PI+R, wherein B is an internal back arc allowance difference value, and the unit is mm; and R is the distance from the middle position of the deflected blade to the center of the rectifier, and the unit is mm.

Description

Technical Field

[0001] This invention relates to the field of machining technology for aero-engine rectifiers, specifically a method for controlling deformation during the machining process of rectifiers. Background Technology

[0002] The rectifier (also known as an integral closed stator blade ring) is the most critical core stator component in an aero-engine. It consists of an inner ring, an outer ring, and multiple blades located between the inner and outer rings. Its function is to decelerate and diffuse the airflow in a channel that expands along the flow direction, and to adjust the airflow direction. Its manufacturing process is complex and technically demanding, and has long been one of the challenges restricting the development of my country's aero-engine industry. To meet the requirements of this type of product, currently, both domestically and internationally, integral forgings made of high-temperature alloys, titanium alloys, and other materials are generally used as the blanks for machining. The component itself is subject to deformation, and the degree of deformation varies. Currently, domestic machining methods for rectifiers are not mature, therefore, it is impossible to completely and effectively control deformation to meet design requirements. The main dimensions involved include blade position accuracy and the height difference between the inner and outer rings. Summary of the Invention

[0003] To address the issues of controlling deformation during rectifier manufacturing and eliminating its impact, this invention provides a deformation control method for the machining process of rectifiers, which can control the deformation during the machining process of rectifiers.

[0004] The technical solution is as follows: a deformation control method for the machining process of a rectifier, characterized in that deformation is controlled by means of blade milling angle compensation during the blade milling process of the rectifier. The blade milling angle compensation is to rotate the machining coordinate angle of the exhaust blade during machining based on the actual position of the intake side blade. The rotation direction is the blade deflection direction. The blade milling is performed using the rotated machining coordinates. The rotation angle C of the blade milling angle compensation is C = B × 180 / π ÷ R, where B is the inner back arc allowance difference in mm, and R is the distance from the middle position of the deflection blade to the center of the rectifier in mm.

[0005] Furthermore, during the milling of rectifier blades, deformation is controlled by means of blade milling model difference compensation. The blade milling model difference compensation is to estimate the actual deformation of the blade after the inlet side blade is processed. Based on the estimation result, the processing model is linearly offset during the processing of the outlet side blade, and the blade milling is performed using the offset processing model.

[0006] Furthermore, the specific method for the differential compensation of the blade milling model is as follows: the blade model is evenly divided into multiple gears along its axial direction, and the estimated direction of the deviation of the gear after the intake side blade is processed is also the direction of the deviation of the theoretical processed blade on the exhaust side. The gears at both ends of the blade model are not deviated, and the remaining gears are linearly interpolated.

[0007] Furthermore, as the deformation of the blade model gradually increases from both ends to the middle, the interpolation value of the gear between the initial gear and the closest maximum offset distance gear = the offset value of the maximum offset distance gear / (the number of gears between the closest maximum offset distance gear and the initial gear + 1) × (the number of gears between the current gear and the initial gear + 1).

[0008] The interpolation value of the gear between the last gear and the nearest maximum offset distance gear = the offset value of the maximum offset distance gear / (the number of gears between the last gear and the nearest maximum offset distance gear + 1) × (the number of gears between the current gear and the last gear + 1).

[0009] Furthermore, the deformation control method during rectifier blade milling also includes layer-by-layer processing and blade milling clamping control. The layer-by-layer processing is to eliminate the reserved allowance layer by layer by milling the inlet and outlet air-side blades multiple times.

[0010] The blade milling clamping control involves clamping the inner and outer rings of the rectifier during clamping, and then machining the inlet and outlet blades.

[0011] Furthermore, the machining process of the rectifier includes blade milling and finish turning. During the finish turning of the rectifier, deformation is controlled by means of finish turning deformation control, finish turning datum conversion control, and turning mode control.

[0012] The deformation control during precision turning involves removing the same amount of allowance when precision turning the air intake and air outlet sides, thereby causing the deformation directions at both ends to be opposite and thus offsetting the amount of deformation.

[0013] The precision turning datum conversion control involves loosening the part to release cutting stress after machining a portion of the allowance, then re-aligning the part for clamping. After re-clamping, the machining datum needs to be redefined, changing from the outer ring datum surface to the inner ring datum surface, and then remachining to the final dimensions.

[0014] The turning method control involves first machining the workpiece cavity, allowing the workpiece to fully deform at its structurally weak points after the cutting stress is released, and then performing the final finishing.

[0015] The beneficial effects of this invention are as follows: if blade deflection occurs during the machining process, it can be addressed by blade milling machining angle compensation. By rotating the machining coordinates, the rotation angle is calculated according to the blade rotation allowance and the part radius, thereby effectively controlling deformation. In addition, deformation can be further controlled through a series of operations such as blade milling machining model difference compensation, layer-by-layer machining, blade milling machining clamping control, precision turning machining deformation control, precision turning machining datum conversion control, and turning mode control. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of angle compensation for blade milling.

[0017] Figure 2 This is a schematic diagram of the differential compensation for the blade milling model;

[0018] Figure 3 Schematic diagram of the tool contact area for blade milling;

[0019] Figure 4 This is a schematic diagram of the tool attachment position after blade machining;

[0020] Figure 5 This is a schematic diagram showing the removal of excess material on the inlet and outlet sides. Detailed Implementation

[0021] A deformation control method for the machining process of a rectifier is disclosed. During the milling of the rectifier blades, deformation is controlled by milling angle compensation. This milling angle compensation involves rotating the machining coordinates of the exhaust blades relative to their actual positions during machining. The rotation direction is the blade deflection direction. Milling is performed using the rotated machining coordinates. The rotation angle C for milling angle compensation is calculated as C = B × 180 / π ÷ R, where B is the difference in inner back arc allowance due to deflection (in mm), and R is the distance from the center of the deflected blade to the center of the rectifier (in mm).

[0022] Combination Figure 1 As shown, when the inner arc 100 is more abundant than the back arc 101, meaning the blade is deflected towards the inner arc side, the machining coordinates shown in the diagram can be rotated counterclockwise (direction A) around the Z-axis (workpiece axis). When the inner arc 100 is less abundant than the back arc 200, the machining coordinates should be rotated clockwise (direction B).

[0023] Furthermore, within the industry, the machining of rectifiers (stator blade rings) is performed from two directions: the inlet side is milled, and the outlet side is milled. These blades are then joined at the middle to form the entire blade. Combined with... Figure 3 , Figure 4First, the inlet side of the blade is machined to its final size. After machining one ring of blades, the part is flipped over. By aligning with the same or related datum and the same angular datum, the outlet side of the blade is machined. Ideally, when the structural rigidity and material properties of the part can guarantee that it will not deform after machining, the joint formed at the middle position after machining the inlet and outlet sides should not exceed 0.01mm. However, when the structural rigidity or material properties of the part cannot guarantee that it will not deform after machining, when the inlet side of the blade is machined and then the blade is flipped over to machine the outlet side, the shape of the inlet side blade will change. This will result in a large joint at the junction with the inlet side blade after the outlet side is theoretically machined, with a C-shaped deformation. The joint should be within 0.01mm near the inner and outer ring flow channels, but the joint near the middle position should be too large (a joint exceeding 0.03mm is unacceptable), thus failing to meet the final blade profile requirements. The X-shaped deformation requires that the cutter mark at the inner arc of the inner ring flow channel and the back arc of the outer ring flow channel be within 0.01mm. However, the cutter mark at the corresponding positions near the back arc of the inner ring flow channel and the inner arc of the outer ring flow channel must maintain the same cutter mark size and be larger (cutter marks exceeding 0.03mm are considered unacceptable). In the figure, 102 is the cutter mark area near the back arc of the outer ring flow channel, 103 is the outer ring flow channel, 104 is the cutter mark area near the inner arc of the outer ring flow channel, 105 is the cutter mark area near the back arc of the inner ring flow channel, 106 is the inner ring flow channel, 107 is the cutter mark area near the inner arc of the inner ring flow channel, 108 is the cutter mark position, 109 is the blade stacking shaft, 110 is the area near the inner ring flow channel, 111 is the middle area, and 112 is the area near the outer ring flow channel.

[0024] Therefore, during the milling of rectifier blades, deformation is also controlled by the difference compensation of the milling model. The difference compensation of the milling model is to estimate the actual deformation of the blade after the inlet side blade is processed. Based on the estimation result, the processing model is linearly offset during the processing of the outlet side blade. The milling is carried out using the offset processing model. The deformation generated after the inlet side blade is processed is controlled by the above method.

[0025] One method for estimating the actual deformation of the intake-side blades is to first machine one blade profile, obtain the size of the tool mark at the tool joint position, and then estimate the actual deformation of the intake-side blade. Specifically, this can be done by creating a sample paste and then using a measuring instrument to analyze the sample paste size to measure the tool joint size; alternatively, it can be done by comparing the model with a coordinate measuring machine (CMM) software to analyze the tool joint size; or it can be evaluated on the equipment by comparing and touching the tool joint size using a feeler gauge. After analyzing the tool joint size, it can be calculated as the deformation size of the intake side.

[0026] The specific method for differential compensation of blade milling model is as follows: the blade model is evenly divided into multiple gears along its axis. The estimated direction of the deformation gear offset after the intake side blade is processed is also the direction of the theoretical blade offset on the exhaust side. The gears at both ends of the blade model do not shift, and the remaining gears are linearly interpolated.

[0027] As the deformation of the blade model gradually increases from both ends to the middle (C-shaped state change), the interpolation value of the gear between the initial gear and the closest maximum offset distance gear = the offset value of the maximum offset distance gear / (the number of gears between the closest maximum offset distance gear and the initial gear + 1) × (the number of gears between the current gear and the initial gear + 1).

[0028] The interpolation value of the gear between the last gear and the nearest maximum offset distance gear = the offset value of the maximum offset distance gear / (the number of gears between the last gear and the nearest maximum offset distance gear + 1) × (the number of gears between the current gear and the last gear + 1).

[0029] Specific combination Figure 2 As shown, the blade deformation mainly changes in the Y-axis. Therefore, after measuring the actual changes, the model's gear shift lines are offset in the Y-axis, meaning the actual machining deformation direction on the intake side is the YM-direction. In the figure, the maximum offset distance for gears 5 to 9 is 0.05mm. Gears 1 and 16 remain unchanged, while the remaining gears are linearly interpolated, allowing for appropriate adjustments to the interpolation values ​​for individual gears. For example: the gears between the initial gear and the nearest maximum offset distance gear are 2, 3, and 4. The offset value of the maximum offset distance gear is 0.05mm. The nearest maximum offset distance gear is 5. The initial gear is 1. The number of gears between them is 2, 3, and 4. The number of gears between the current gear and the initial gear is the second gear. From the above data, we know that the interpolation value of the third gear is 0.05 / (3+1)×(1+1)=0.025mm. In actual operation, it is allowed to slightly adjust or take an approximate value on the calculated value. The data for gears 10-15 are slightly adjusted.

[0030] In addition, deformation control methods during rectifier blade milling also include layer-by-layer machining and blade milling clamping control. Layer-by-layer machining involves milling the inlet and outlet blades multiple times to gradually eliminate the reserved allowance. Specifically, for rectifier blade milling, the common machining scheme of "machining the connecting blades on both the inlet and outlet sides" is adopted. A semi-finish milling step is added to the process: semi-finish milling of the inlet and outlet blades (leaving a 0.3mm allowance for the final size) → finish milling of the inlet and outlet blades (leaving a 0.1mm allowance for the final size) → finish milling of the inlet and outlet blades (0mm allowance). The distribution of machining allowance is adjusted in the process, and layer-by-layer milling is carried out to fully release cutting stress during the process, thereby reducing deformation.

[0031] The clamping control for blade milling involves clamping the inner and outer rings of the rectifier during clamping before machining the inlet and outlet blades. Specifically, the tooling design considers that if only one side of the inner or outer ring is clamped for positioning, the blade, located between the inner and outer rings, acts as a connector. During machining, the structural rigidity weakens, and material stress is redistributed and eventually reaches equilibrium. Therefore, an unclamped inner or outer ring and blade will deform excessively. Thus, both the inner and outer rings must be clamped to prevent deformation during blade milling. The rectifier center positioning stop requires a small clearance fit (0mm~0.02mm) to minimize the impact of deformation.

[0032] The machining process of the rectifier includes blade milling and finish turning. During finish turning, deformation is controlled through finish turning deformation control, finish turning datum conversion control, and turning method control. The finish turning deformation control involves removing the same allowance during finish turning of both the inlet and outlet sides, thus ensuring that the deformation directions at both ends are opposite and offsetting the deformation amount. Specifically, in conjunction with... Figure 5 During the milling process of the rectifier blades, the mounting edge needs to be clamped. This results in a mounting edge of at least 4mm on the outer diameter or inner hole. Therefore, after finishing the reference or precision machining, removing the mounting edge will cause significant stress release on the outer or inner ring, leading to overall deformation. This changes the height difference between the inner and outer rings, causing a change in the distance between the blade X-value and the outer ring reference designed for the part, resulting in out-of-tolerance blade position. During precision machining, the removal of the outer ring leads to deformation. Therefore, the deformation must be controlled within a certain range to ensure the final dimensions are acceptable. The most important basic principle is to ensure that the removal allowances on both the inlet and outlet sides are roughly the same, thus ensuring that the deformation directions at both ends are opposite and can cancel each other out. Therefore, during the precision machining process, the removal allowances after precision machining on both sides should also be consistent (X1=X2). X1 and X2 should be as small as possible when conditions permit. In the figure, 113 represents the outer edge plate.

[0033] The precision turning datum conversion control involves loosening the part after machining a certain allowance to release cutting stress, then re-aligning and clamping the part. After re-clamping, the machining datum needs to be redefined, changing from the outer ring datum surface to the inner ring datum surface, and then remachining to the final dimensions. Specifically, the precision turning process consists of two steps: precision turning the intake side → precision turning the exhaust side. The intake side is turned first because the design datum is on the outer ring of the intake side, and the theoretical distance from it to the blade stacking shaft needs to be guaranteed in the final state. In the precision turning of the intake side, the most important step is the semi-precision turning step, where after machining to a certain allowance (e.g., 0.3mm), the part is loosened to release cutting stress, and then re-aligned and clamped. Throughout the process, measurements are taken using a dial indicator to ensure that the part meets the requirements. After re-clamping, the machining datum needs to be redefined, changing from the outer ring datum surface to the inner ring datum surface, and then remachining to the final dimensions. After the semi-finish turning step, the reference is transferred to the inner ring. Since the change in the inner ring is small, the change between the inner and outer ring bodies and the blade is small when the inner ring is used as the reference. Only the change in the outer ring needs to be controlled. If the outer ring is used as the machining reference after the semi-finish turning step, the outer ring will deform more, and the inner ring surface will deviate from the actual position, resulting in a deviation from the blade position.

[0034] Turning control involves first machining the workpiece's cavity, allowing the workpiece to fully deform at its structurally weakest points after the cutting stress is released, before performing final finishing. Specifically, the turning method should prioritize machining the cavity, allowing the part to fully deform at its structurally weakest points after the cutting stress is released, followed by final finishing, and finally finishing the design datum diameter and datum surface. The machining process employs cyclic cutting with a decreasing cutting amount per layer, programmed accordingly. To reduce cutting stress deformation, a larger feed rate and linear speed can be selected for roughing, but a smaller feed rate and linear speed are needed for finishing to control deformation.

[0035] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling deformation during the machining process of a rectifier, characterized in that, During the milling of rectifier blades, deformation is controlled by milling angle compensation. The milling angle compensation involves rotating the machining coordinates of the exhaust blades based on the actual position of the intake blades. The rotation direction is the blade deflection direction. Milling is performed using the rotated machining coordinates. The rotation angle C for milling angle compensation is C = B × 180 / π ÷ R, where B is the inner back arc allowance difference in mm, and R is the distance from the middle position of the deflection blade to the center of the rectifier in mm. During the milling of rectifier blades, deformation is also controlled by the difference compensation of the milling model. The difference compensation of the milling model is to estimate the actual deformation of the blade after the inlet side blade is processed. Based on the estimation result, the processing model is linearly offset during the processing of the outlet side blade, and the milling is performed using the offset processing model.

2. The deformation control method for the machining process of a rectifier according to claim 1, characterized in that: The specific method for the differential compensation of the blade milling model is as follows: the blade model is evenly divided into multiple gears along its axial direction. The estimated direction of the gear offset after the intake side blade is processed is also the direction of the theoretical blade offset on the exhaust side. The gears at both ends of the blade model do not offset, and the remaining gears are linearly interpolated.

3. The deformation control method for the machining process of a rectifier according to claim 2, characterized in that: As the deformation of the blade model gradually increases from both ends to the middle, the interpolation value of the gear between the initial gear and the closest maximum offset distance gear = the offset value of the maximum offset distance gear / (the number of gears between the closest maximum offset distance gear and the initial gear + 1) × (the number of gears between the current gear and the initial gear + 1). The interpolation value of the gear between the last gear and the nearest maximum offset distance gear = the offset value of the maximum offset distance gear / (the number of gears between the last gear and the nearest maximum offset distance gear + 1) × (the number of gears between the current gear and the last gear + 1).

4. The deformation control method for the machining process of a rectifier according to claim 1, characterized in that: The control deformation method during rectifier blade milling also includes layer-by-layer processing and blade milling clamping control. The layer-by-layer processing is to eliminate the reserved allowance layer by layer by milling the inlet and outlet air-side blades multiple times. The blade milling clamping control involves clamping the inner and outer rings of the rectifier during clamping, and then machining the inlet and outlet blades.

5. The deformation control method for the machining process of a rectifier according to claim 1, characterized in that: The machining process of the rectifier includes blade milling and finish turning. During the finish turning of the rectifier, deformation is controlled by means of finish turning deformation control, finish turning datum conversion control, and turning mode control. The deformation control during precision turning involves removing the same amount of allowance when precision turning the air intake and air outlet sides, thereby causing the deformation directions at both ends to be opposite and thus offsetting the amount of deformation. The precision turning datum conversion control involves loosening the part to release cutting stress after machining a portion of the allowance, then re-aligning the part for clamping. After re-clamping, the machining datum needs to be redefined, changing from the outer ring datum surface to the inner ring datum surface, and then remachining to the final dimensions. The turning method control involves first machining the workpiece cavity, allowing the workpiece to fully deform at its structurally weak points after the cutting stress is released, and then performing the final finishing.

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