A numerical control machining method for self-adapting compensation of radial face parallelism of blade root crown

Abstract

The application discloses a numerical control machining method for self-adapting compensation of blade root crown radial surface parallelism, and belongs to the technical field of steam turbine blade machining. The application is used for solving the problems of poor root crown radial surface parallelism and poor consistency caused by the existing blade machining method. The application comprises the following steps: offsetting the blade along the X axis and the Z axis, rotating the blade along the X axis and the Y axis, and compensating the root crown position degree, so that the blade is in the set position in the state of being tightly pressed by the top pin after finishing the finishing machining; machining the blade part except the blade crown related surface to the finished state; selecting a point A1 on the blade crown back radial side close to the steam outlet side and a point A2 on the blade crown back radial side close to the steam inlet side as detection points, and obtaining the Z-direction difference value R19 and R22 between the two points A1 and A2 in the state of the blade being loosened and being tightly pressed respectively; calculating the difference value R23 of R19 and R22 as the compensation amount of the machine tool parameters, and performing the finishing machining on the blade crown related surface. The application is used for compensating machining of the steam turbine blade.

Description

Technical Field

[0001] This invention relates to a CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap, belonging to the field of turbine blade machining technology. Background Technology

[0002] The XH499 turbine unit has eight moving blades with a total length of 465mm, a steam duct length of 362mm, and an axial width of 112mm. Due to the thin steam duct and small blade crown chord width, the form and position tolerances of the root crown radial surface are strictly required. However, the excessive length and narrowness of the steam duct, coupled with the excessive axial width of the root crown, results in poor overall blade rigidity and makes machining difficult. When machining this blade using a five-axis machine tool, various factors cause the parallelism of the root crown radial surface to be compromised, resulting in an error of 0.1° to 0.6° in the angle between the root crown radial surface and the blade root radial surface.

[0003] Existing processing methods require workers to figure out the general pattern of parallelism deviation based on the processing conditions, and then adjust the A-axis at the blade crown of the machine tool to ensure the consistency of the radial plane parallelism of the root crown. However, this method has the following problems:

[0004] 1. It relies on the work experience of the staff, and the work error is relatively large. The consistency of the radial plane parallelism of the root and crown cannot be guaranteed.

[0005] 2. The radial angle difference of the blades of the XH499 turbine unit varies greatly, and traditional machining methods cannot be adjusted, which brings great difficulty to conventional machining. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of poor parallelism and consistency of the root-crown radial plane caused by existing blade machining methods, and to provide a CNC machining method that adaptively compensates for the parallelism of the root-crown radial plane of the blade.

[0007] The present invention discloses a CNC machining method for adaptively compensating for the parallelism of the radial surface of the root cap of a blade, comprising:

[0008] S1. Using the blade height direction as the X-axis, the blade axial direction as the Y-axis, and the radial direction as the Z-axis, offset the blade along the X-axis and Z-axis, rotate the blade along the X-axis and Y-axis, and compensate for the root crown position of the blade so that the blade is in the set position after finishing and the ejector pin is tightened.

[0009] S2. Process the blade parts other than the crown-related surfaces until the finished product is completed;

[0010] S3. Select point A1, which is radially closer to the steam outlet side of the blade crown, and point A2, which is radially closer to the steam inlet side of the blade crown, as detection points. Obtain the Z-direction drop value R19 between points A1 and A2 when the blade is loose, and obtain the Z-direction drop value R22 between points A1 and A2 when the blade is tight.

[0011] S4. Calculate the difference between R19 and R22, and record the difference as R23;

[0012] S5. Using R23 as the compensation amount of the machine tool parameters, perform precision milling on the relevant surfaces of the blade crown to achieve the adjustment of the parallelism of the radial surface of the root crown.

[0013] Preferably, the offset values ​​of the X-axis and Z-axis in S1 are stored in database Mem0, the rotation values ​​of the X-axis and Y-axis are stored in database Mem0, and the root crown position compensation values ​​are stored in database Mem2.

[0014] Preferably, the compensation amount R23 of the machine tool parameters mentioned in S5 is stored in the database Mem2, and the database Mem2 is called to perform fine milling on the blade crown related surface.

[0015] Preferably, the blade crown related surface S2 includes: inner radial, back radial, steam inlet side and steam outlet side.

[0016] Preferably, the specific method for obtaining the Z-axis drop value R19 between points A1 and A2 in the leaf-released state as described in S3 includes:

[0017] S3-1, Loosen the pin;

[0018] S3-2. Use the probe to detect the Z-axis measured data of two points A1 and A2, and assign them to the R parameter respectively. Assign the measured data of point A1 to R17 and the measured data of point A2 to R18.

[0019] S3-3. Calculate the Z-direction elevation difference between points A1 and A2, and assign the difference value to R19:

[0020] R19 = R17 - R18.

[0021] Preferably, the specific method for obtaining the Z-axis drop value R22 between points A1 and A2 under the blade clamping state described in S3 includes:

[0022] S3-4. Tighten the ejector pin;

[0023] S3-5. Use the probe to detect the Z-axis measured data of two points A1 and A2, and assign them to the R parameter respectively. Assign the measured data of point A1 to R20 and the measured data of point A2 to R21.

[0024] S3-6. Calculate the Z-direction elevation difference between points A1 and A2, and assign the difference value to R22:

[0025] R22 = R20 - R21.

[0026] The CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap proposed in this invention has the following advantages:

[0027] 1. The adaptive compensation A-axis angle machining method solves the problems of poor parallelism and consistency of the blade radial surface, eliminates machine tool reversing backlash, achieves consistent blade machining under different conditions, ensures surface finish, and improves machining accuracy. The adaptive compensation method adjusts the A-axis compensation amount of the blade crown by using the difference in measured data between the allowance left for finishing the radial surface after loosening and re-tightening the ejector pin on the blade crown side, ensuring that the root-crown parallelism is within 0.02mm.

[0028] 2. It effectively replaces the manual method of measuring parallelism to find patterns, greatly saving processing and assembly cycles. Attached Figure Description

[0029] Figure 1 This is a schematic diagram showing the positions of two detection points, A1, which is radially closer to the steam outlet side and A2, which is radially closer to the steam inlet side, as described in this invention. Detailed Implementation

[0030] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0033] Example 1:

[0034] The following is combined with Figure 1 This embodiment describes a CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root and crown.

[0035] Blade machining A0 state: blade height offset is the X-axis, rotation is the A-axis; blade axial direction is the Y-axis, radial direction is the Z-axis.

[0036] With no issues on the machine tool's A-axis, the radial surface of the blade root maintains a flatness within 0.01 mm whether the ejector pin is tightened or loosened. Only the blade crown portion experiences significant deformation when rotating around the A-axis.

[0037] It includes:

[0038] S1. Using the blade height direction as the X-axis, the blade axial direction as the Y-axis, and the radial direction as the Z-axis, offset the blade along the X-axis and Z-axis, rotate the blade along the X-axis and Y-axis, and compensate for the root crown position of the blade so that the blade is in the set position after finishing and the ejector pin is tightened.

[0039] S2. Process the blade parts other than the crown-related surfaces until the finished product is completed;

[0040] S3. Select point A1, which is radially closer to the steam outlet side of the blade crown, and point A2, which is radially closer to the steam inlet side of the blade crown, as detection points. Obtain the Z-direction drop value R19 between points A1 and A2 when the blade is loose, and obtain the Z-direction drop value R22 between points A1 and A2 when the blade is tight.

[0041] S4. Calculate the difference between R19 and R22, and record the difference as R23;

[0042] S5. Using R23 as the compensation amount of the machine tool parameters, perform precision milling on the relevant surfaces of the blade crown to achieve the adjustment of the parallelism of the radial surface of the root crown.

[0043] Furthermore, the offset values ​​of the X-axis and Z-axis mentioned in S1 are stored in database Mem0, the rotation values ​​of the X-axis and Y-axis are stored in database Mem0, and the root crown position compensation values ​​are stored in database Mem2.

[0044] Furthermore, the compensation amount R23 of the machine tool parameters mentioned in S5 is stored in the database Mem2, and the database Mem2 is called to perform fine milling on the blade crown related surface.

[0045] Furthermore, the blade crown-related surfaces described in S2 include: inner radial, back radial, inlet side, and outlet side.

[0046] Furthermore, the specific method for obtaining the Z-axis drop value R19 between points A1 and A2 in the leaf-released state, as described in S3, includes:

[0047] S3-1, Loosen the pin;

[0048] S3-2. Use the probe to detect the Z-axis measured data of two points A1 and A2, and assign them to the R parameter respectively. Assign the measured data of point A1 to R17 and the measured data of point A2 to R18.

[0049] S3-3. Calculate the Z-direction elevation difference between points A1 and A2, and assign the difference value to R19:

[0050] R19 = R17 - R18.

[0051] Furthermore, the specific method for obtaining the Z-axis drop value R22 between points A1 and A2 under the blade clamping state, as described in S3, includes:

[0052] S3-4. Tighten the ejector pin;

[0053] S3-5. Use the probe to detect the Z-axis measured data of two points A1 and A2, and assign them to the R parameter respectively. Assign the measured data of point A1 to R20 and the measured data of point A2 to R21.

[0054] S3-6. Calculate the Z-direction elevation difference between points A1 and A2, and assign the difference value to R22:

[0055] R22 = R20 - R21.

[0056] In this embodiment, a CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root and crown is proposed. During the machining process, the parallelism of the radial surface of the blade root and crown is adaptively compensated. In addition, the position degree of the radial surface of the blade root and crown is adaptively compensated by patent CN114147536B and a CNC machining method for adaptively compensating for the position degree of the blade. Under the premise that the position degree of the root and crown is consistent, the parallelism of the radial surface of the blade root and crown is adjusted to ensure the consistency of the assembly gap.

[0057] In this embodiment, S2 processes the blade portion excluding the blade crown-related surface, with a precision milling allowance of 0.2 mm (this allowance is used for subsequent precision milling of the blade crown-related surface after A-axis compensation).

[0058] In this embodiment, a probe is used to detect the Z-direction values ​​at two detection points, A1 and A2. The Z-direction refers to the direction of the back radial direction upwards.

[0059] In this embodiment, S4 calculates the difference between R19 and R22, and the difference is denoted as R23. In practical applications:

[0060] R23 = R19 - R22 - 0.01

[0061] Since the actual material feeding condition is affected by the machine tool reversing clearance, the value of 0.01 can be adjusted according to the processing condition.

[0062] In this invention, after finishing, the blade crown area undergoes rotational deformation due to cutting stress and other factors. At this point, it is necessary to measure the rotation angle of the radial surface of the blade crown after releasing the stress by loosening the ejector pin and the rotation angle of the radial surface of the blade crown after the ejector pin is tightened again and automatically adjusted by the machine tool, and record the difference; this difference is the theoretical angle of A-axis deformation rotation.

[0063] By changing the processing method of this type of blade structure, and using automatic program adjustment instead of the traditional mode of manual measurement, pattern finding and adjustment, the problem of poor parallelism of the root and crown radial surfaces of the blades was effectively solved. The problem of blade torsional deformation caused by special structure and cutting stress was eliminated, resulting in better processing quality and consistency. The parallelism of the root and crown radial surfaces of all blades is within 0.02mm, the fit of adjacent blades is controlled, and the processing and assembly cycle is saved.

[0064] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A CNC machining method for adaptively compensating for the parallelism of the radial surface of the root and crown of a blade, characterized in that, It includes: S1. Using the blade height direction as the X-axis, the blade axial direction as the Y-axis, and the radial direction as the Z-axis, offset the blade along the X-axis and Z-axis, rotate the blade along the X-axis and Y-axis, and compensate for the root crown position of the blade so that the blade is in the set position after finishing and the ejector pin is tightened. S2. Process the blade parts other than the crown-related surfaces until the finished product is completed; S3. Select point A1, which is radially closer to the steam outlet side of the blade crown, and point A2, which is radially closer to the steam inlet side of the blade crown, as detection points. Obtain the Z-direction drop value R19 between points A1 and A2 when the blade is loose, and obtain the Z-direction drop value R22 between points A1 and A2 when the blade is tight. S4. Calculate the difference between R19 and R22, and record the difference as R23; S5. Using R23 as the compensation amount of the machine tool parameters, perform precision milling on the relevant surfaces of the blade crown to achieve the adjustment of the parallelism of the radial surface of the root crown.

2. The CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap according to claim 1, characterized in that, The offset values ​​of the X-axis and Z-axis in S1 are stored in database Mem0, the rotation values ​​of the X-axis and Y-axis are stored in database Mem0, and the root crown position compensation values ​​are stored in database Mem2.

3. The CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap according to claim 2, characterized in that, The compensation amount R23 of the machine tool parameters mentioned in S5 is stored in the database Mem2, and the database Mem2 is called to perform fine milling on the blade crown related surface.

4. The CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap according to claim 1, characterized in that, The blade crown related surfaces described in S2 include: inner radial, back radial, inlet side, and outlet side.

5. The CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap according to claim 1, characterized in that, The specific method described in S3 for obtaining the Z-axis drop value R19 between points A1 and A2 in the open blade state includes: S3-1, Loosen the pin; S3-2. Use the probe to detect the Z-axis measured data of two points A1 and A2, and assign them to the R parameter respectively. Assign the measured data of point A1 to R17 and the measured data of point A2 to R18. S3-3. Calculate the Z-direction elevation difference between points A1 and A2, and assign the difference value to R19: R19 = R17 - R18.

6. The CNC machining method for adaptively compensating for the parallelism of the radial surface of the blade root cap according to claim 1, characterized in that, The specific method described in S3 for obtaining the Z-axis drop value R22 between points A1 and A2 under the blade clamping condition includes: S3-4. Tighten the ejector pin; S3-5. Use the probe to detect the Z-axis measured data of two points A1 and A2, and assign the values ​​to the R parameter respectively. Assign the negative measured data of point A1 to R20, and the negative measured data of point A2 to R21. S3-6. Calculate the Z-direction elevation difference between points A1 and A2, and assign the difference value to R22: R22 = R20 - R21.

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